@article{lennon_abramoff_allison_burckhardt_deangelis_dunne_frey_friedlingstein_hawkes_hungate_et al._2024, title={Priorities, opportunities, and challenges for integrating microorganisms into Earth system models for climate change prediction}, ISSN={["2150-7511"]}, DOI={10.1128/mbio.00455-24}, abstractNote={ABSTRACT}, journal={MBIO}, author={Lennon, J. T. and Abramoff, R. Z. and Allison, S. D. and Burckhardt, R. M. and DeAngelis, K. M. and Dunne, J. P. and Frey, S. D. and Friedlingstein, P. and Hawkes, C. V. and Hungate, B. A. and et al.}, year={2024}, month={Mar} }
 @article{dutta_houdinet_nandakafle_kafle_hawkes_garcia_2023, title={Agrobacterium tumefaciens-mediated transformation of Nigrospora sp. isolated from switchgrass leaves and antagonistic toward plant pathogens}, volume={215}, ISSN={["1872-8359"]}, url={http://dx.doi.org/10.1016/j.mimet.2023.106849}, DOI={10.1016/j.mimet.2023.106849}, abstractNote={Nigrospora is a diverse genus of fungi colonizing plants through endophytic, pathogenic, or saprobic interactions. Endophytic isolates can improve growth and development of host plants, as well as their resistance to microbial pathogens, but exactly how they do so remains poorly understood. Developing a reliable transformation method is crucial to investigate these mechanisms, in particular to identify pivotal genes for specific functions that correlate with specific traits. In this study, we identified eight isolates of Nigrospora sp. internally colonizing the leaves of switchgrass plants cultivated in North Carolina. Using an Agrobacterium tumefaciens-mediated transformation approach with control and GFP-expressing vectors, we report the first successful transformation of two Nigrospora isolates. Finally, we demonstrate that wild-type and transgenic isolates both negatively impact the growth of two plant pathogens in co-culture conditions, Bipolaris maydis and Parastagonospora nodorum, responsible for the Southern Leaf Blight and Septoria Nodorum Blotch diseases, respectively. The GFP-transformed strains developed here can therefore serve as accurate reporters of spatial interactions in future studies of Nigrospora and pathogens in the plant. Finally, the transformation method we describe lays the foundation for further genetic research on the Nigrospora genus to expand our mechanistic understanding of plant-endophyte interactions.}, journal={JOURNAL OF MICROBIOLOGICAL METHODS}, author={Dutta, Summi and Houdinet, Gabriella and NandaKafle, Gitanjali and Kafle, Arjun and Hawkes, Christine V. and Garcia, Kevin}, year={2023}, month={Dec} }
 @article{aimone_giauque_hawkes_2023, title={Fungal Symbionts Generate Water-Saver and Water-Spender Plant Drought Strategies via Diverse Effects on Host Gene Expression}, ISSN={["2471-2906"]}, DOI={10.1094/PBIOMES-01-22-0006-FI}, abstractNote={ Foliar fungal endophytes are known to alter plant physiology but the mechanisms by which they do so remain poorly understood. We focused on how plant gene expression was altered by six fungal strains that generated “water-saver” and “water-spender” drought physiologies in a C4 grass, Panicum hallii. Water-saver physiologies have lower plant water loss, improved wilt resistance, and higher survival compared with water-spender strategies. We expected that fungi within each functional group would have similar effects on P. hallii, and this was largely true for plant physiology but not for plant gene expression. When we focused only on genes that were differentially expressed relative to fungus-free controls, we found surprisingly little overlap in plant differentially expressed genes or gene regulatory pathways across the fungal treatments, including within and between the water-saver and water-spender strategies. Nevertheless, using lasso regression, we identified a small subset of genes that predicted 39 and 53% of the variation in plant wilt resistance and water loss, respectively. These results suggest that fungal effects on plant transcription may identify how they extend the plant phenotype, and the comparison across multiple fungi allows us to differentiate broadly fungal-responsive plant genes versus those plant genes that respond only to single fungal taxa. The genes identified here could be targeted for future study to understand their function and, ultimately, represent candidates for precision breeding efforts to increase plant drought tolerance. }, journal={PHYTOBIOMES JOURNAL}, author={Aimone, Catherine D. and Giauque, Hannah and Hawkes, Christine V.}, year={2023}, month={Mar} }
 @article{hawkes_allen_balint-kurti_cowger_2023, title={Manipulating the plant mycobiome to enhance resilience: Ecological and evolutionary opportunities and challenges}, volume={19}, ISSN={["1553-7374"]}, DOI={10.1371/journal.ppat.1011816}, number={12}, journal={PLOS PATHOGENS}, author={Hawkes, Christine V. and Allen, Xavious and Balint-Kurti, Peter and Cowger, Christina}, year={2023}, month={Dec} }
 @article{vries_lau_hawkes_semchenko_2023, title={Plant-soil feedback under drought: does history shape the future?}, volume={38}, ISSN={["1872-8383"]}, DOI={10.1016/j.tree.2023.03.001}, abstractNote={Plant-soil feedback (PSF) is widely recognised as a driver of plant community composition, but understanding of its response to drought remains in its infancy. Here, we provide a conceptual framework for the role of drought in PSF, considering plant traits, drought severity, and historical precipitation over ecological and evolutionary timescales. Comparing experimental studies where plants and microbes do or do not share a drought history (through co-sourcing or conditioning), we hypothesise that plants and microbes with a shared drought history experience more positive PSF under subsequent drought. To reflect real-world responses to drought, future studies need to explicitly include plant-microbial co-occurrence and potential co-adaptation and consider the precipitation history experienced by both plants and microbes.}, number={8}, journal={TRENDS IN ECOLOGY & EVOLUTION}, author={Vries, Franciska and Lau, Jennifer and Hawkes, Christine and Semchenko, Marina}, year={2023}, month={Aug}, pages={708–718} }
 @article{heckman_rueda_bonnette_aspinwall_khasanova_hawkes_juenger_fay_2022, title={Legacies of precipitation influence primary production in Panicum virgatum}, volume={11}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-022-05281-x}, abstractNote={Precipitation is a key driver of primary production worldwide, but primary production does not always track year-to-year variation in precipitation linearly. Instead, plant responses to changes in precipitation may exhibit time lags, or legacies of past precipitation. Legacies can be driven by multiple mechanisms, including persistent changes in plant physiological and morphological traits and changes to the physical environment, such as plant access to soil water. We used three precipitation manipulation experiments in central Texas, USA to evaluate the magnitude, duration, and potential mechanisms driving precipitation legacies on aboveground primary production of the perennial C 4  grass, Panicum virgatum. Specifically, we performed a rainout shelter study, where eight genotypes grew under different precipitation regimes; a transplant study, where plants that had previously grown in a rainout shelter under different precipitation regimes were moved to a common environment; and a mesocosm study, where the effect of swapping precipitation regime was examined with a single genotype. Across these experiments, plants previously grown under wet conditions generally performed better than expected when exposed to drought. Panicum virgatum exhibited stronger productivity legacies of past wet years on current-year responses to drought than of past dry years on current-year responses to wet conditions. Additionally, previous year tiller counts, a proxy for meristem availability, were important in determining legacy effects on aboveground production. As climate changes and precipitation extremes-both dry and wet-become more common, these results suggest that populations of P. virgatum may become less resilient.}, journal={OECOLOGIA}, author={Heckman, Robert W. and Rueda, Austin and Bonnette, Jason E. and Aspinwall, Michael J. and Khasanova, Albina and Hawkes, Christine V. and Juenger, Thomas E. and Fay, Philip A.}, year={2022}, month={Nov} }
 @article{evans_allison_hawkes_2022, title={Microbes, memory and moisture: Predicting microbial moisture responses and their impact on carbon cycling}, volume={3}, ISSN={["1365-2435"]}, url={https://doi.org/10.1111/1365-2435.14034}, DOI={10.1111/1365-2435.14034}, abstractNote={Abstract}, journal={FUNCTIONAL ECOLOGY}, publisher={Wiley}, author={Evans, Sarah and Allison, Steven and Hawkes, Christine}, year={2022}, month={Mar} }
 @article{sandy_bui_aba_ruiz_paszalek_connor_hawkes_2022, title={Plant Host Traits Mediated by Foliar Fungal Symbionts and Secondary Metabolites}, volume={6}, ISSN={["1432-184X"]}, url={https://doi.org/10.1007/s00248-022-02057-x}, DOI={10.1007/s00248-022-02057-x}, abstractNote={Fungal symbionts living inside plant leaves ("endophytes") can vary from beneficial to parasitic, but the mechanisms by which the fungi affect the plant host phenotype remain poorly understood. Chemical interactions are likely the proximal mechanism of interaction between foliar endophytes and the plant, as individual fungal strains are often exploited for their diverse secondary metabolite production. Here, we go beyond single strains to examine commonalities in how 16 fungal endophytes shift plant phenotypic traits such as growth and physiology, and how those relate to plant metabolomics profiles. We inoculated individual fungi on switchgrass, Panicum virgatum L. This created a limited range of plant growth and physiology (2-370% of fungus-free controls on average), but effects of most fungi overlapped, indicating functional similarities in unstressed conditions. Overall plant metabolomics profiles included almost 2000 metabolites, which were broadly correlated with plant traits across all the fungal treatments. Terpenoid-rich samples were associated with larger, more physiologically active plants and phenolic-rich samples were associated with smaller, less active plants. Only 47 metabolites were enriched in plants inoculated with fungi relative to fungus-free controls, and of these, Lasso regression identified 12 metabolites that explained from 14 to 43% of plant trait variation. Fungal long-chain fatty acids and sterol precursors were positively associated with plant photosynthesis, conductance, and shoot biomass, but negatively associated with survival. The phytohormone gibberellin, in contrast, was negatively associated with plant physiology and biomass. These results can inform ongoing efforts to develop metabolites as crop management tools, either by direct application or via breeding, by identifying how associations with more beneficial components of the microbiome may be affected.}, journal={MICROBIAL ECOLOGY}, author={Sandy, Moriah and Bui, Tina I. and Aba, Kenia Segura and Ruiz, Nestor and Paszalek, John and Connor, Elise W. and Hawkes, Christine V.}, year={2022}, month={Jun} }
 @article{leizeaga_hicks_manoharan_hawkes_rousk_2021, title={Drought legacy affects microbial community trait distributions related to moisture along a savannah grassland precipitation gradient}, volume={109}, ISSN={["1365-2745"]}, DOI={10.1111/1365-2745.13550}, abstractNote={Abstract}, number={9}, journal={JOURNAL OF ECOLOGY}, author={Leizeaga, Ainara and Hicks, Lettice C. and Manoharan, Lokeshwaran and Hawkes, Christine V. and Rousk, Johannes}, year={2021}, month={Sep}, pages={3195–3210} }
 @article{hawkes_kjoller_raaijmakers_riber_christensen_rasmussen_christensen_dahl_westergaard_nielsen_et al._2021, title={Extension of Plant Phenotypes by the Foliar Microbiome}, volume={72}, ISSN={["1545-2123"]}, DOI={10.1146/annurev-arplant-080620-114342}, abstractNote={ The foliar microbiome can extend the host plant phenotype by expanding its genomic and metabolic capabilities. Despite increasing recognition of the importance of the foliar microbiome for plant fitness, stress physiology, and yield, the diversity, function, and contribution of foliar microbiomes to plant phenotypic traits remain largely elusive. The recent adoption of high-throughput technologies is helping to unravel the diversityand spatiotemporal dynamics of foliar microbiomes, but we have yet to resolve their functional importance for plant growth, development, and ecology. Here, we focus on the processes that govern the assembly of the foliar microbiome and the potential mechanisms involved in extended plant phenotypes. We highlight knowledge gaps and provide suggestions for new research directions that can propel the field forward. These efforts will be instrumental in maximizing the functional potential of the foliar microbiome for sustainable crop production. }, journal={ANNUAL REVIEW OF PLANT BIOLOGY, VOL 72, 2021}, author={Hawkes, Christine V. and Kjoller, Rasmus and Raaijmakers, Jos M. and Riber, Leise and Christensen, Svend and Rasmussen, Simon and Christensen, Jan H. and Dahl, Anders Bjorholm and Westergaard, Jesper Cairo and Nielsen, Mads and et al.}, year={2021}, pages={823–846} }
 @article{whitaker_giauque_timmerman_birk_hawkes_2021, title={Local Plants, Not Soils, Are the Primary Source of Foliar Fungal Community Assembly in a C4 Grass}, volume={8}, ISSN={["1432-184X"]}, url={https://doi.org/10.1007/s00248-021-01836-2}, DOI={10.1007/s00248-021-01836-2}, abstractNote={Microbial communities, like their macro-organismal counterparts, assemble from multiple source populations and by processes acting at multiple spatial scales. However, the relative importance of different sources to the plant microbiome and the spatial scale at which assembly occurs remains debated. In this study, we analyzed how source contributions to the foliar fungal microbiome of a C4 grass differed between locally abundant plants and soils across an abiotic gradient at different spatial scales. Specifically, we used source-sink analysis to assess the likelihood that fungi in leaves from Panicum hallii came from three putative sources: two plant functional groups (C4 grasses and dicots) and soil. We expected that physiologically similar C4 grasses would be more important sources to P. hallii than dicots. We tested this at ten sites in central Texas spanning a steep precipitation gradient. We also examined source contributions at three spatial scales: individual sites (local), local plus adjacent sites (regional), or all sites (gradient-wide). We found that plants were substantially more important sources than soils, but contributions from the two plant functional groups were similar. Plant contributions overall declined and unexplained variation increased as mean annual precipitation increased. This source-sink analysis, combined with partitioning of beta-diversity into nestedness and turnover components, indicated high dispersal limitation and/or strong environmental filtering. Overall, our results suggest that the source-sink dynamics of foliar fungi are primarily local, that foliar fungi spread from plant-to-plant, and that the abiotic environment may affect fungal community sourcing both directly and via changes to host plant communities.}, journal={MICROBIAL ECOLOGY}, publisher={Springer Science and Business Media LLC}, author={Whitaker, Briana K. and Giauque, Hannah and Timmerman, Corey and Birk, Nicolas and Hawkes, Christine V}, year={2021}, month={Aug} }
 @article{zhalnina_hawkes_shade_firestone_pett-ridge_2021, title={Managing Plant Microbiomes for Sustainable Biofuel Production}, volume={5}, ISSN={["2471-2906"]}, url={https://doi.org/10.1094/PBIOMES-12-20-0090-E}, DOI={10.1094/PBIOMES-12-20-0090-E}, abstractNote={ The development of environmentally sustainable, economical, and reliable sources of energy is one of the great challenges of the 21st century. Large-scale cultivation of cellulosic feedstock crops (henceforth, bioenergy crops) is considered one of the most promising renewable sources for liquid transportation fuels. However, the mandate to develop a viable cellulosic bioenergy industry is accompanied by an equally urgent mandate to deliver not only cheap reliable biomass but also ecosystem benefits, including efficient use of water, nitrogen, and phosphorous; restored soil health; and net negative carbon emissions. Thus, sustainable bioenergy crop production may involve new agricultural practices or feedstocks and should be reliable, cost effective, and minimal input, without displacing crops currently grown for food production on fertile land. In this editorial perspective for the Phytobiomes Journal Focus Issue on Phytobiomes of Bioenergy Crops and Agroecosystems, we consider the microbiomes associated with bioenergy crops, the effects beneficial microbes have on their hosts, and potential ecosystem impacts of these interactions. We also address outstanding questions, major advances, and emerging biotechnological strategies to design and manipulate bioenergy crop microbiomes. This approach could simultaneously increase crop yields and provide important ecosystem services for a sustainable energy future. }, number={1}, journal={PHYTOBIOMES JOURNAL}, publisher={Scientific Societies}, author={Zhalnina, Kateryna and Hawkes, Christine and Shade, Ashley and Firestone, Mary K. and Pett-Ridge, Jennifer}, year={2021}, pages={3–13} }
 @article{lee_hawkes_2021, title={Plant and Soil Drivers of Whole-Plant Microbiomes: Variation in Switchgrass Fungi from Coastal to Mountain Sites}, volume={5}, ISSN={["2471-2906"]}, url={https://doi.org/10.1094/PBIOMES-07-20-0056-FI}, DOI={10.1094/PBIOMES-07-20-0056-FI}, abstractNote={ Plant-associated microbial diversity is regulated by dispersal from local and regional species pools, as well as filtering by the environment and plant host. However, few studies have simultaneously examined microbial community variation in multiple plant-associated habitats across multiple sites; thus, it is unclear what scales and filters are most important in shaping whole-plant microbiome diversity. To address this, we characterized fungal communities associated with switchgrass (Panicum virgatum L.) leaves, roots, and soils within and across 14 stands spanning mountain to coastal ecoregions of North Carolina. Niche differences at small scales (i.e., less than half a kilometer) best explained variation in fungal communities. However, the specific environmental drivers of fungal community composition differed for leaves, roots, and soils. Leaf and root fungi were both affected by plant height, whereas soil fungi were controlled by stand age. Different soil properties were important for fungi in all plant-associated habitats: K, P, and pH for leaves; clay, Mn, and pH for roots; and clay, dissolved organic carbon, total inorganic N, and Cu for soils. Climate and spatial variables were not significant, further supporting the key role of plant and soil properties. Advances such as these will help us explain, predict, and manipulate microbial assemblages that support plant growth in managed and natural systems. }, number={1}, journal={PHYTOBIOMES JOURNAL}, publisher={Scientific Societies}, author={Lee, Marissa R. and Hawkes, Christine V}, year={2021}, pages={69–79} }
 @article{kivlin_hawkes_papeş_treseder_averill_2021, title={The future of microbial ecological niche theory and modeling}, volume={231}, url={https://doi.org/10.1111/nph.17373}, DOI={10.1111/nph.17373}, abstractNote={This article is a Commentary on Davison et al. (2021), 231: 763–776.}, number={2}, journal={New Phytologist}, publisher={Wiley}, author={Kivlin, Stephanie N. and Hawkes, Christine V. and Papeş, Monica and Treseder, Kathleen K. and Averill, Colin}, year={2021}, month={Jul}, pages={508–511} }
 @article{lee_hawkes_2021, title={Widespread co-occurrence of Sebacinales and arbuscular mycorrhizal fungi in switchgrass roots and soils has limited dependence on soil carbon or nutrients}, volume={3}, ISSN={["2572-2611"]}, url={https://doi.org/10.1002/ppp3.10181}, DOI={10.1002/ppp3.10181}, abstractNote={Societal Impact Statement}, number={5}, journal={PLANTS PEOPLE PLANET}, publisher={Wiley}, author={Lee, Marissa R. and Hawkes, Christine V}, year={2021}, month={Sep}, pages={614–626} }
 @article{kiniry_arthur_banick_fritschi_wu_hawkes_2020, title={Effects of Plant-Soil Feedback on Switchgrass Productivity Related to Microbial Origin}, url={https://doi.org/10.3390/agronomy10121860}, DOI={10.3390/agronomy10121860}, abstractNote={A great deal of effort has been applied to maximizing switchgrass (Panicum virgatum L.) production for bioenergy by leveraging existing local adaptation to climate and via nutrient management in this perennial grass crop. However, the biotic component of soils can also affect plant production and long-term suitability at a given site. Here, we tested how productivity of four switchgrass cultivars were affected by four microbial sources from the Great Plains. All inoculum soil sources were previously conditioned by a mixture of switchgrass cultivars, allowing us to explicitly address plant-soil feedback effects. Microbial soil inocula were added to a consistent background soil to avoid physicochemical variation across the sources. We found that the soil microbial inoculum source mattered more than cultivar in determining switchgrass biomass. The addition of microbes resulted in smaller plants, with the largest plants found on control soils with no inoculum, but some inocula were less negative than others. There was no geographic matching between cultivars and soil microbial inoculum, suggesting little local adaptation to the biotic component of soils. In addition, measurements of fungal root colonization suggest that fungi are not responsible for the observed patterns. Based on these results, we suggest that switchgrass cultivation could benefit from considering effects of the soil biota. Additional work is needed to generalize these patterns over time, to a wider geographic area, and to a broader range of cultivars.}, journal={Agronomy}, author={Kiniry, James R. and Arthur, Caroline E. and Banick, Katherine M. and Fritschi, Felix B. and Wu, Yanqi and Hawkes, Christine V.}, year={2020}, month={Nov} }
 @article{hawkes_shinada_kivlin_2020, title={Historical climate legacies on soil respiration persist despite extreme changes in rainfall}, volume={143}, ISSN={["0038-0717"]}, DOI={10.1016/j.soilbio.2020.107752}, abstractNote={How soil microbial respiration responds to climate change can be constrained by historical climate. Understanding the duration of such legacy effects is key to determining how much they matter for projecting future ecosystem carbon cycling. Here, we tested whether extreme changes in rainfall could overcome constraints imposed by historical rainfall on how soil respiration responds to moisture. We predicted that larger shifts in rainfall regime would alter the magnitude or sensitivity (slope) of the respiration response to moisture compared to smaller changes in rainfall relative to historical conditions. Over 4.5 years, we imposed rain treatments ranging from extreme dry to extreme wet conditions that varied by ~400%, as well as ambient and historical mean rainfall controls. Rain treatments were applied to shortgrass or tallgrass vegetation that represented lower and higher biomass inputs, respectively, to test how shifts in soil resources might affect respiration moisture responses. We found high resistance to altered rainfall in the field, with persistent legacies indicated by no change in the respiration response to moisture among treatment and control rain treatments. The intrinsic respiration response to moisture under controlled laboratory conditions was also unaffected by field rain treatments. In response to field vegetation treatment, there was 10–30% more soil respiration in tallgrass compared to shortgrass that was paralleled by an increase in soil dissolved organic carbon, but no change in moisture sensitivity consistent with independent resource and climate effects. Soil bacteria and fungi were unchanged across all treatments and were largely generalists, suggesting high community as well as functional resistance to change. Climate legacies on soil microbial communities have the potential to modify our expectations for the rate of acclimation and adaptation to altered climate conditions.}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Hawkes, Christine V and Shinada, Mio and Kivlin, Stephanie N.}, year={2020}, month={Apr} }
 @article{heckman_khasanova_johnson_weber_bonnette_aspinwall_reichmann_juenger_fay_hawkes_2020, title={Plant biomass, not plant economics traits, determines responses of soil CO2 efflux to precipitation in the C-4 grass Panicum virgatum}, volume={108}, ISSN={["1365-2745"]}, DOI={10.1111/1365-2745.13382}, abstractNote={Abstract}, number={5}, journal={JOURNAL OF ECOLOGY}, author={Heckman, Robert W. and Khasanova, Albina R. and Johnson, Nicholas S. and Weber, Soren and Bonnette, Jason E. and Aspinwall, Michael J. and Reichmann, Lara G. and Juenger, Thomas E. and Fay, Philip A. and Hawkes, Christine V}, year={2020}, month={Sep}, pages={2095–2106} }
 @article{cooperdock_hawkes_xu_breecker_2020, title={Soil Water Content and Soil Respiration Rates Are Reduced for Years Following Wildfire in a Hot and Dry Climate}, volume={34}, ISSN={["1944-9224"]}, DOI={10.1029/2020GB006699}, abstractNote={Abstract}, number={12}, journal={GLOBAL BIOGEOCHEMICAL CYCLES}, author={Cooperdock, Sol C. and Hawkes, Christine V. and Xu, Derry R. and Breecker, Daniel O.}, year={2020}, month={Dec} }
 @article{crawford_hawkes_2020, title={Soil precipitation legacies influence intraspecific plant–soil feedback}, volume={101}, url={https://doi.org/10.1002/ecy.3142}, DOI={10.1002/ecy.3142}, abstractNote={Abstract}, number={10}, journal={Ecology}, publisher={Wiley}, author={Crawford, Kerri M. and Hawkes, Christine V.}, year={2020}, month={Oct} }
 @article{kivlin_hawkes_2020, title={Spatial and temporal turnover of soil microbial communities is not linked to function in a primary tropical forest}, volume={101}, url={https://doi.org/10.1002/ecy.2985}, DOI={10.1002/ecy.2985}, abstractNote={Abstract}, number={4}, journal={Ecology}, publisher={Wiley}, author={Kivlin, Stephanie N. and Hawkes, Christine V.}, year={2020}, month={Apr} }
 @article{hawkes_bull_lau_2020, title={Symbiosis and stress: how plant microbiomes affect host evolution}, volume={375}, url={https://doi.org/10.1098/rstb.2019.0590}, DOI={10.1098/rstb.2019.0590}, abstractNote={Existing paradigms for plant microevolution rarely acknowledge the potential impacts of diverse microbiomes on evolutionary processes. Many plant-associated microorganisms benefit the host via access to resources, protection from pathogens, or amelioration of abiotic stress. In doing so, they alter the plant's perception of the environment, potentially reducing the strength of selection acting on plant stress tolerance or defence traits or altering the traits that are the target of selection. We posit that the microbiome can affect plant microevolution via (1) manipulation of plant phenotypes in ways that increase plant fitness under stress and (2) direct microbial responses to the environment that benefit the plant. Both mechanisms might favour plant genotypes that attract or stimulate growth of the most responsive microbial populations or communities. We provide support for these scenarios using infectious disease and quantitative genetics models. Finally, we discuss how beneficial plant–microbiome associations can evolve if traditional mechanisms maintaining cooperation in pairwise symbioses, namely partner fidelity, partner choice and fitness alignment, also apply to the interactions between plants and diverse foliar and soil microbiomes. To understand the role of the plant microbiome in host evolution will require a broad ecological understanding of plant–microbe interactions across both space and time.}, number={1808}, journal={Philosophical Transactions of the Royal Society B: Biological Sciences}, publisher={The Royal Society}, author={Hawkes, Christine V. and Bull, James J. and Lau, Jennifer A.}, year={2020}, month={Sep}, pages={20190590} }
 @article{giauque_connor_hawkes_2019, title={Endophyte traits relevant to stress tolerance, resource use and habitat of origin predict effects on host plants}, volume={221}, ISSN={["1469-8137"]}, url={https://doi.org/10.1111/nph.15504}, DOI={10.1111/nph.15504}, abstractNote={Summary}, number={4}, journal={NEW PHYTOLOGIST}, publisher={Wiley}, author={Giauque, Hannah and Connor, Elise W. and Hawkes, Christine V.}, year={2019}, month={Mar}, pages={2239–2249} }
 @article{ecological mechanisms underlying soil bacterial responses to rainfall along a steep natural precipitation gradient_2018, url={http://dx.doi.org/10.1093/femsec/fiy001}, DOI={10.1093/femsec/fiy001}, abstractNote={ABSTRACT Changes in the structure and function of soil microbial communities can drive substantial ecosystem feedbacks to altered precipitation. However, the ecological mechanisms underlying community responses to environmental change are not well understood. We used an 18‐month soil reciprocal transplant experiment along a steep precipitation gradient to quantify how changes in rainfall affected bacterial community structure. We also conducted an enhanced dispersal treatment to ask whether higher immigration rates of taxa from the surrounding environment would accelerate community responses to climate change. Finally, we addressed how the composition of soil bacteria communities was related to the functional response of soil respiration to moisture in these treatments. Bacterial community structure (OTU abundance) and function (respiration rates) changed little in response to manipulation of either rainfall environment or dispersal rates. Although most bacteria were ecological generalists, a subset of specialist taxa, over 40% of which were Actinobacteria, tended to be more abundant in the rainfall environment that matched their original conditions. Bacteria community composition was an important predictor of the respiration response to moisture. Thus, the high compositional resistance of microbial communities dictated respiration responses to altered rainfall in this system.}, journal={FEMS Microbiology Ecology}, year={2018}, month={Feb} }
 @article{connor_hawkes_2018, title={Effects of extreme changes in precipitation on the physiology of C4 grasses}, volume={188}, url={https://doi.org/10.1007/s00442-018-4212-5}, DOI={10.1007/s00442-018-4212-5}, abstractNote={Climatic patterns are expected to become more extreme, with changes in precipitation characterized by heavier rainfall and prolonged dry periods. Yet, most studies focus on persistent moderate changes in precipitation, limiting our understanding of how ecosystems will function in the future. We examined the effects of extreme changes in precipitation on leaf-level and ecosystem CO 2  and H 2 O exchange of three native C4 bunchgrasses (Andropogon gerardii, Panicum virgatum, and Sorghastrum nutans) over 3 years. Grasses were grown in three precipitation treatments: extreme dry, mean, and extreme wet based on historical rainfall records. After 3 years, plants were 45% smaller in the extreme dry treatment relative to the mean and extreme high treatment, which did not differ. We also found that an extreme decrease in precipitation caused reductions of 55, 40, and 40% in leaf-level photosynthesis (A net ), stomatal conductance (g s ), and water use efficiency (WUE), respectively. Extreme increases in precipitation inhibited leaf-level WUE, with a 44% reduction relative to the mean treatment. At the ecosystem level, both an extreme increase and decrease in precipitation reduced net CO 2  and water fluxes relative to plants grown with mean levels of precipitation. Net water fluxes (ET) were reduced by an average of 74% in the extreme dry and extreme wet treatment relative to mean treatment; net carbon fluxes followed a similar trend, with average reductions of 68% (NEE) and 100% (R e ). Unlike moderate climate change, extreme increases in precipitation may be just as detrimental as extreme decreases in precipitation in shifting grassland physiology.}, number={2}, journal={Oecologia}, publisher={Springer Nature}, author={Connor, Elise W. and Hawkes, Christine V.}, year={2018}, month={Oct}, pages={355–365} }
 @article{heterogeneity in arbuscular mycorrhizal fungal communities may contribute to inconsistent plant-soil feedback in a neotropical forest_2018, url={http://dx.doi.org/10.1007/s11104-018-3777-4}, DOI={10.1007/s11104-018-3777-4}, journal={Plant and Soil}, year={2018}, month={Nov} }
 @article{legacies in switchgrass resistance to and recovery from drought suggest that good years can sustain plants through bad years_2018, url={http://dx.doi.org/10.1007/s12155-017-9879-7}, DOI={10.1007/s12155-017-9879-7}, journal={BioEnergy Research}, year={2018}, month={Mar} }
 @article{soil carbon cycling proxies: understanding their critical role in predicting climate change feedbacks_2018, url={http://dx.doi.org/10.1111/gcb.13926}, DOI={10.1111/gcb.13926}, abstractNote={Abstract}, journal={Global Change Biology}, year={2018}, month={Mar} }
 @article{tropical tree species effects on soil ph and biotic factors and the consequences for macroaggregate dynamics_2018, url={http://dx.doi.org/10.3390/f9040184}, DOI={10.3390/f9040184}, abstractNote={Physicochemical and biotic factors influence the binding and dispersivity of soil particles, and thus control soil macroaggregate formation and stability. Although soil pH influences dispersivity, it is usually relatively constant within a site, and thus not considered a driver of aggregation dynamics. However, land-use change that results in shifts in tree-species composition can result in alteration of soil pH, owing to species-specific traits, e.g., support of nitrogen fixation and Al accumulation. In a long-term, randomized complete block experiment in which climate, soil type, and previous land-use history were similar, we evaluated effects of individual native tropical tree species on water-stable macroaggregate size distributions in an Oxisol. We conducted this study at La Selva Biological Station in Costa Rica, in six vegetation types: 25-year-old plantations of four tree species grown in monodominant stands; an unplanted Control; and an adjacent mature forest. Tree species significantly influenced aggregate proportions in smaller size classes (0.25–1.0 mm), which were correlated with fine-root growth and litterfall. Tree species altered soil pH differentially. Across all vegetation types, the proportion of smaller macroaggregates declined significantly as soil pH increased (p ≤ 0.0184). This suggests that alteration of pH influences dispersivity, and thus macroaggregate dynamics, thereby playing a role in soil C, N, and P cycling.}, journal={Forests}, year={2018}, month={Apr} }
 @article{brave new world_2017, url={http://dx.doi.org/10.1007/s10533-017-0316-y}, DOI={10.1007/s10533-017-0316-y}, journal={Biogeochemistry}, year={2017}, month={Mar} }
 @article{hawkes_waring_rocca_kivlin_2017, title={Historical climate controls soil respiration responses to current soil moisture}, url={https://doi.org/10.1073/pnas.1620811114}, DOI={10.1073/pnas.1620811114}, abstractNote={Significance}, journal={Proceedings of the National Academy of Sciences}, author={Hawkes, Christine V. and Waring, Bonnie G. and Rocca, Jennifer D. and Kivlin, Stephanie N.}, year={2017}, month={Jun} }
 @article{microbial tools in agriculture require an ecological context: stress-dependent non-additive symbiont interactions_2017, url={http://dx.doi.org/10.2134/agronj2016.10.0568}, DOI={10.2134/agronj2016.10.0568}, abstractNote={Core Ideas
Leaf fungal symbionts represent a potential new tool in agriculture.
Effective fungal application requires an understanding of their interactions.
Fungal interactions resulted in non‐additive plant growth and wilt responses.
Fungal metabolites indicated qualitative additive, synergistic, or antagonistic plant responses.
Fungal trait dissimilarity predicted the size of plant response deviations.
}, journal={Agronomy Journal}, year={2017} }
 @article{regardless of n-substrate, multiple fungal root endophytes isolated from pastures outgrow and outcompete those isolated from undisturbed sites_2017, url={http://dx.doi.org/10.1016/j.pedobi.2017.05.006}, DOI={10.1016/j.pedobi.2017.05.006}, abstractNote={Edaphic properties such as soil nutrients structure belowground fungal communities and alter their intimate interactions with plants. Yet little work has compared the traits of fungal root endophytes and tested if specific soil nutrients determine their growth and competition. We hypothesized that fungi isolated from particular resource environments should grow and compete better when resources matched their “home” environment. We conducted experiments to compare growth rate and competitive ability of eight fungal root endophytes, cultured from either low nutrient undisturbed sites or from sites converted to high nutrient pastures, varying the nutrient environments to match the different sites. In isolation, biomass depended on nutrient limitation and fungal identity. Pasture endophytes all had high biomass in high nitrogen environments while endophytes from undisturbed sites showed greater variation among isolates. In competition, growth differences quantitatively depended on the fungus’s identity, its competitor’s identity and nutrients, yet pasture fungi out-competed “undisturbed” fungi in nearly every case. Rapid growth and competitive ability appears to be a trait of these fungal endophytes isolated from pastures and not solely a product of high nutrients, which may inhibit successful reintroduction of fungi from undisturbed sites.}, journal={Pedobiologia}, year={2017}, month={Jul} }
 @inbook{the predictive power of ecological niche modeling for global arbuscular mycorrhizal fungal biogeography_2017, url={http://dx.doi.org/10.1007/978-3-319-56363-3_7}, DOI={10.1007/978-3-319-56363-3_7}, abstractNote={The distributions of arbuscular mycorrhizal (AM) fungal communities are driven by climate, soil nutrients, and plant community composition. However, these distributions are estimated at the community level and AM fungal taxa will respond to selection pressure of global change at the species level. Thus, ecological niche models of individual AM fungal taxa may be an informative approach to predict AM fungal composition and function under future climates at the global scale. Here we present the first attempt to model AM fungal distributions with ecological niche models for the widespread AM fungal taxon Rhizophagus irregularis (formerly Glomus intraradices). We show that despite varying the definition of the operational taxonomic unit (OTU) for R. irregularis, the predicted distributions of this species complex are consistently affected by a positive association with soil moisture. The spatial extent of ecological niche models affected the predicted distribution of R. irregularis, with climatic drivers and resources affecting its distribution more strongly in the northern and southern hemispheres, respectively. Given that AM fungi are not dispersal limited and coexist at the landscape scale relevant for ecological niche model predictions, this widely distributed fungal clade provides a robust case study to apply hypothesis-driven distributional models to predict the biogeography of microorganisms.}, booktitle={Biogeography of Mycorrhizal Symbiosis}, year={2017} }
 @article{hawkes_connor_2017, title={Translating Phytobiomes from Theory to Practice: Ecological and Evolutionary Considerations}, volume={1}, url={https://doi.org/10.1094/PBIOMES-05-17-0019-RVW}, DOI={10.1094/PBIOMES-05-17-0019-RVW}, abstractNote={ The tremendous potential of the plant microbiome to improve plant growth and production means that microbes are in the process of becoming an everyday tool in agronomic practices. However, historically field applications of microbes have had low success. We propose that development and optimization of microbiome treatments will benefit from the integration of ecological and evolutionary niche theory into plant microbiome studies. Thus, we review several niche-based processes that can aid in the development and implementation of microbiome treatments. Current predictive approaches include evolutionary history, habitat origin, ecological traits, resource trade, and gene signatures, none of which are mutually exclusive. A robust predictive framework must further account for observed plasticity and context dependence in microbial function. Development of microbiome treatments that will successfully establish in the field can also benefit from a better understanding of niche-based processes such as niche partitioning to limit competitive interactions and maximize persistence, priority effects to allow establishment before resident taxa, storage effects that take advantage of temporal variation in niche availability, and local adaptation to specific environments. Using endophytic fungi as examples, we illustrate current knowledge and gaps in these areas. Finally, we address existing limitations to the broad-scale development of successful microbiome tools. }, number={2}, journal={Phytobiomes Journal}, publisher={Scientific Societies}, author={Hawkes, Christine V. and Connor, Elise W.}, year={2017}, month={Jan}, pages={57–69} }
 @inbook{climate change, microbes, and soil carbon cycling_2016, url={http://dx.doi.org/10.21775/9781910190319.07}, DOI={10.21775/9781910190319.07}, abstractNote={Microbial responses to climate change will partly control the balance of soil carbon storage and loss under future temperature and precipitation conditions. We propose four classes of response mechanisms that can allow for a more general understanding of microbial climate responses. We further explore how a subset of these mechanisms results in microbial responses to climate change using simulation modelling. Specifically, we incorporate soil moisture sensitivity into two current enzyme-driven models of soil carbon cycling and find that moisture has large effects on predictions for soil carbon and microbial pools. Empirical efforts to distinguish among response mechanisms will facilitate our ability to further develop models with improved accuracy. Introduction There is twice as much carbon in soils as in the atmosphere ( Jenkinson et al., 1991), making below-ground responses to climate change an important aspect of ecosystem responses and feedbacks to climate. Nevertheless, below-ground responses to climate change remain a large source of uncertainty (Solomon et al., 2007), such that earth system models poorly predict current soil carbon pools (Todd-Brown et al., 2013). This is probably due, in part, to historical assumptions of purely abiotic controls of soil carbon cycling and the lack of a strong mechanistic framework for how soil microbes respond to environmental change and the resulting impacts on the fate of soil carbon (Chapin III et al., 2009; Ogle et al., 2010). Soil respiration is the main pathway for the transfer of carbon from terrestrial to atmospheric pools (Schlesinger and Andrews, 2000). Soil microbes may also make a larger contribution to the building of soil organic carbon than previously thought (Kindler et al., 2006; Liang and Balser, 2008, 2011; Potthoff et al., 2008). For example, mycorrhizal fungi can be the dominant pathway through which carbon from plants enters the soil pool, with hyphal turnover representing ~60% of soil organic matter inputs and the remaining ~40% due to fine root turnover and leaf litter (Godbold et al., 2006). Furthermore, the type of mycorrhizal fungus can determine soil carbon: Averill et al. (2014) found that ecosystems dominated by plants colonized by ectomycorrhizal fungi stored 70% more soil carbon per unit nitrogen than ecosystems dominated by plants associated with arbuscular mycorrhizal fungi. Thus, the effects of climate change on the activity and physiology of the soil microbes will partly determine what proportion of annual soil carbon input is respired versus stored in the longterm reservoir of soil organic carbon (Chapin III et al., 2002). Shifts in microbial community composition, abundance and function have been observed in climate change experiments manipulating temperature, precipitation, carbon dioxide and their interactions (e.g. Castro et al., 2010; Cheng et al., 2012; Harper et al., 2005; Hawkes et al., 2011; Horz et al., 2004, 2005; Lindberg et al., 2002; Liu et al., 2009; Staddon et al., 2003; Zogg et al., 1997). Although results appear to be site specific, some broader patterns can be gleaned from metaanalyses. Based on 32 experimental temperature manipulations, warming increased soil respiration by 20% and net nitrogen mineralization by 46% (Rustad et al., 2001). Blankinship et al. (2011) analysed 75 experimental climate studies and found}, booktitle={Climate Change and Microbial Ecology: Current Research and Future Trends}, year={2016} }
 @article{ectomycorrhizal fungi slow soil carbon cycling_2016, url={http://dx.doi.org/10.1111/ele.12631}, DOI={10.1111/ele.12631}, abstractNote={Abstract}, journal={Ecology Letters}, year={2016}, month={Aug} }
 @article{historical and current climate drive spatial and temporal patterns in fungal endophyte diversity_2016, url={http://dx.doi.org/10.1016/j.funeco.2015.12.005}, DOI={10.1016/j.funeco.2015.12.005}, abstractNote={Horizontally-transmitted foliar endophytic fungi can moderate plant tolerance to abiotic and biotic stress. Previous studies have found correlations between climate and endophyte beta diversity, but were unable to clearly separate drivers related to long-term climate, annual weather, and host plants. To address this, we characterized endophyte communities in the perennial C4 grass, Panicum hallii, across a precipitation gradient in central Texas over 3 years. A total of 65 unique leaf endophytes were isolated and identified based on ITS and LSU regions of rDNA. Mean annual rainfall and temperature were the primary drivers of endophyte richness and community composition, followed by annual weather conditions. In contrast, little explanatory value was provided by plant host traits, vegetation structure, or spatial factors. The importance of historical climate and annual weather in endophyte distributions suggests that species sort by environment and are likely to be affected by future climate change.}, journal={Fungal Ecology}, year={2016}, month={Apr} }
 @article{historical precipitation predictably alters the shape and magnitude of microbial functional response to soil moisture_2016, url={http://dx.doi.org/10.1111/gcb.13219}, DOI={10.1111/gcb.13219}, abstractNote={Abstract}, journal={Global Change Biology}, year={2016}, month={May} }
 @article{intraspecific variation in precipitation responses of a widespread c4grass depends on site water limitation_2016, url={http://dx.doi.org/10.1093/jpe/rtw040}, DOI={10.1093/jpe/rtw040}, abstractNote={Aims Variation in precipitation strongly influences plant growth, species distributions and genetic diversity. Intraspecific variation in phenotypic plasticity, the ability of a genotype to alter its growth, morphology or physiology in response to the environment, could influence species responses to changing precipitation and climate change. Despite this, the patterns and mechanisms of intraspecific variation in plasticity to variable precipitation, and the degree to which genotype responses to precipitation are influenced by variation in edaphic conditions, remain poorly understood. Thus, we determined whether genotypes of a widespread C4 grass (Panicum virgatum L., switchgrass) varied in aboveground productivity in response to changes in precipitation, and if site edaphic conditions modified genotype aboveground productivity responses to precipitation. We also determined if genotype productivity responses to precipitation are related to plasticity in underlying growth and phenological traits. Methods Nine P.  virgatum genotypes originating from an aridity gradient were grown under four treatments spanning the 10th to the 90th percentiles of annual precipitation at two sites in central Texas: one site with deep, fine-textured soils and another site with shallow, coarse-textured soils. We measured volumetric soil water content (VWC), aboveground net primary productivity (ANPP), tiller production (tiller number), average tiller mass, canopy height, leaf area index (LAI) and flowering time on all plants at both sites and examined genotype responses to changes in precipitation. Important Findings Across precipitation treatments, VWC was 39% lower and more variable at the site with shallow, coarse-textured soils compared to the site with deep, fine-textured soils. ANPP averaged across genotypes and precipitation treatments was also 103% higher at the site with deep, fine-textured soils relative to the site with shallow, coarse-textured soils, indicating substantial differences in site water limitation. Where site water limitation was higher, ANPP of most genotypes increased with increasing precipitation. Where site water limitation was less, genotypes expressed variable plasticity in response to precipitation, from no change to almost a 5-fold increase in ANPP with increasing precipitation. Genotype ANPP increased with greater tiller mass, LAI and later flowering time at both sites, but not with tiller number at either site. Genotype ANPP plasticity increased with genotype tiller mass and LAI plasticity at the site with deep, fine-textured soils, and only with genotype tiller mass plasticity at the site with shallow, coarse-textured soils. Thus, variation in genotype ANPP plasticity was explained primarily by variation in tiller and leaf growth. Genotype ANPP plasticity was not associated with temperature or aridity at the genotype’s origin. Edaphic factors such as soil depth and texture may alter genotype ANPP responses to precipitation, and the underlying growth traits contributing to the ANPP response. Thus, edaphic factors may contribute to spatial variation in genotype performance and success under altered precipitation.}, journal={Journal of Plant Ecology}, year={2016}, month={Apr} }
 @article{plant and root endophyte assembly history: interactive effects on native and exotic plants_2016, url={http://dx.doi.org/10.1890/15-0635.1}, DOI={10.1890/15-0635.1}, abstractNote={Abstract}, journal={Ecology}, year={2016}, month={Feb} }
 @article{promises and challenges of eco-physiological genomics in the field: tests of drought responses in switchgrass_2016, url={http://dx.doi.org/10.1104/pp.16.00545}, DOI={10.1104/pp.16.00545}, abstractNote={Physiological and gene expression analyses across field and greenhouse experiments highlight diverse gene expression patterns that produce physiologically similar responses to soil water deficits. Identifying the physiological and genetic basis of stress tolerance in plants has proven to be critical to understanding adaptation in both agricultural and natural systems. However, many discoveries were initially made in the controlled conditions of greenhouses or laboratories, not in the field. To test the comparability of drought responses across field and greenhouse environments, we undertook three independent experiments using the switchgrass reference genotype Alamo AP13. We analyzed physiological and gene expression variation across four locations, two sampling times, and three years. Relatively similar physiological responses and expression coefficients of variation across experiments masked highly dissimilar gene expression responses to drought. Critically, a drought experiment utilizing small pots in the greenhouse elicited nearly identical physiological changes as an experiment conducted in the field, but an order of magnitude more differentially expressed genes. However, we were able to define a suite of several hundred genes that were differentially expressed across all experiments. This list was strongly enriched in photosynthesis, water status, and reactive oxygen species responsive genes. The strong across-experiment correlations between physiological plasticity—but not differential gene expression—highlight the complex and diverse genetic mechanisms that can produce phenotypically similar responses to various soil water deficits.}, journal={Plant Physiology}, year={2016}, month={May} }
 @article{simulating diverse native c4 perennial grasses with varying rainfall_2016, url={http://dx.doi.org/10.1016/j.jaridenv.2016.07.004}, DOI={10.1016/j.jaridenv.2016.07.004}, abstractNote={Rainfall is recognized as a major factor affecting the rate of plant growth development. The impact of changes in amount and variability of rainfall on growth and production of different forage grasses needs to be quantified to determine how climate change can impact rangelands. Comparative studies to evaluate the growth of several perennial forage species at different rainfall rates will provide useful information by identifying forage management strategies under various rainfall scenarios. In this study, the combination of rainfall changes and soil types on the plant growth of 10 perennial forage species was investigated with both the experimental methods, using rainout shelters, and with the numerical methods using the plant growth simulation model, ALMANAC. Overall, most species significantly increased basal diameter and height as rainfall increased. Like measured volume, simulated yields for all species generally increased as rainfall increased. But, large volume and yield increases were only observed between 350 and 850 mm/yr. Simulating all species growing together competing agrees relatively well with observed plant volumes at low rainfall treatment, while simulating all species growing separately was slightly biased towards overestimation on low rainfall effect. Both simulations agree relatively well with observed plant volume at high rainfall treatment.}, journal={Journal of Arid Environments}, year={2016}, month={Nov} }
 @article{temporal and spatial variation of soil bacteria richness, composition, and function in a neotropical rainforest_2016, url={http://dx.doi.org/10.1371/journal.pone.0159131}, DOI={10.1371/journal.pone.0159131}, abstractNote={The high diversity of tree species has traditionally been considered an important controller of belowground processes in tropical rainforests. However, soil water availability and resources are also primary regulators of soil bacteria in many ecosystems. Separating the effects of these biotic and abiotic factors in the tropics is challenging because of their high spatial and temporal heterogeneity. To determine the drivers of tropical soil bacteria, we examined tree species effects using experimental tree monocultures and secondary forests at La Selva Biological Station in Costa Rica. A randomized block design captured spatial variation and we sampled at four dates across two years to assess temporal variation. We measured bacteria richness, phylogenetic diversity, community composition, biomass, and functional potential. All bacteria parameters varied significantly across dates. In addition, bacteria richness and phylogenetic diversity were affected by the interaction of vegetation type and date, whereas bacteria community composition was affected by the interaction of vegetation type and block. Shifts in bacteria community richness and composition were unrelated to shifts in enzyme function, suggesting physiological overlap among taxa. Based on the observed temporal and spatial heterogeneity, our understanding of tropical soil bacteria will benefit from additional work to determine the optimal temporal and spatial scales for sampling. Understanding spatial and temporal variation will facilitate prediction of how tropical soil microbes will respond to future environmental change.}, journal={PLOS ONE}, year={2016}, month={Jul} }
 @article{tree species, spatial heterogeneity, and seasonality drive soil fungal abundance, richness, and composition in neotropical rainforests_2016, url={http://dx.doi.org/10.1111/1462-2920.13342}, DOI={10.1111/1462-2920.13342}, abstractNote={Summary}, journal={Environmental Microbiology}, year={2016}, month={Dec} }
 @article{microbial-mediated redistribution of ecosystem nitrogen cycling can delay progressive nitrogen limitation_2015, url={http://dx.doi.org/10.1007/s10533-015-0160-x}, DOI={10.1007/s10533-015-0160-x}, journal={Biogeochemistry}, year={2015}, month={Nov} }
 @article{resilience vs. historical contingency in microbial responses to environmental change_2015, url={http://dx.doi.org/10.1111/ele.12451}, DOI={10.1111/ele.12451}, abstractNote={Abstract}, journal={Ecology Letters}, year={2015}, month={Jul} }
 @article{waring_hawkes_2015, title={Short-Term Precipitation Exclusion Alters Microbial Responses to Soil Moisture in a Wet Tropical Forest}, volume={69}, url={http://dx.doi.org/10.1007/s00248-014-0436-z}, DOI={10.1007/s00248-014-0436-z}, abstractNote={Many wet tropical forests, which contain a quarter of global terrestrial biomass carbon stocks, will experience changes in precipitation regime over the next century. Soil microbial responses to altered rainfall are likely to be an important feedback on ecosystem carbon cycling, but the ecological mechanisms underpinning these responses are poorly understood. We examined how reduced rainfall affected soil microbial abundance, activity, and community composition using a 6-month precipitation exclusion experiment at La Selva Biological Station, Costa Rica. Thereafter, we addressed the persistent effects of field moisture treatments by exposing soils to a controlled soil moisture gradient in the lab for 4 weeks. In the field, compositional and functional responses to reduced rainfall were dependent on initial conditions, consistent with a large degree of spatial heterogeneity in tropical forests. However, the precipitation manipulation significantly altered microbial functional responses to soil moisture. Communities with prior drought exposure exhibited higher respiration rates per unit microbial biomass under all conditions and respired significantly more CO2 than control soils at low soil moisture. These functional patterns suggest that changes in microbial physiology may drive positive feedbacks to rising atmospheric CO2 concentrations if wet tropical forests experience longer or more intense dry seasons in the future.}, number={4}, journal={Microbial Ecology}, publisher={Springer Science \mathplus Business Media}, author={Waring, Bonnie G. and Hawkes, Christine V.}, year={2015}, month={May}, pages={843–854} }
 @article{glinka_hawkes_2014, title={Environmental Controls on Fungal Community Composition and Abundance Over 3 Years in Native and Degraded Shrublands}, volume={68}, DOI={10.1007/s00248-014-0443-0}, abstractNote={Soil fungal communities have high local diversity and turnover, but the relative contribution of environmental and regional drivers to those patterns remains poorly understood. Local factors that contribute to fungal diversity include soil properties and the plant community, but there is also evidence for regional dispersal limitation in some fungal communities. We used different plant communities with different soil conditions and experimental manipulations of both vegetation and dispersal to distinguish among these factors. Specifically, we compared native shrublands with former native shrublands that had been disturbed or converted to pasture, resulting in soils progressively more enriched in carbon and nutrients. We tested the role of vegetation via active removal, and we manipulated dispersal by adding living soil inoculum from undisturbed native sites. Soil fungi were tracked for 3 years, with samples taken at ten time points from June 2006 to June 2009. We found that soil fungal abundance, richness, and community composition responded primarily to soil properties, which in this case were a legacy of plant community degradation. In contrast, dispersal had no effect on soil fungi. Temporal variation in soil fungi was partly related to drought status, yet it was much broader in native sites compared to pastures, suggesting some buffering due to the increased soil resources in the pasture sites. The persistence of soil fungal communities over 3 years in this study suggests that soil properties can act as a strong local environmental filter. Largely persistent soil fungal communities also indicate the potential for strong biotic resistance and soil legacies, which presents a challenge for both the prediction of how fungi respond to environmental change and our ability to manipulate fungi in efforts such as ecosystem restoration.}, number={4}, journal={Microb Ecol}, publisher={Springer Science \mathplus Business Media}, author={Glinka, Clare and Hawkes, Christine V.}, year={2014}, month={Jun}, pages={807–817} }
 @article{standish_hobbs_mayfield_bestelmeyer_suding_battaglia_eviner_hawkes_temperton_cramer_et al._2014, title={Resilience in ecology: Abstraction, distraction, or where the action is?}, volume={177}, DOI={10.1016/j.biocon.2014.06.008}, abstractNote={Increasingly, the success of management interventions aimed at biodiversity conservation are viewed as being dependent on the ‘resilience’ of the system. Although the term ‘resilience’ is increasingly used by policy makers and environmental managers, the concept of ‘resilience’ remains vague, varied and difficult to quantify. Here we clarify what this concept means from an ecological perspective, and how it can be measured and applied to ecosystem management. We argue that thresholds of disturbance are central to measuring resilience. Thresholds are important because they offer a means to quantify how much disturbance an ecosystem can absorb before switching to another state, and so indicate whether intervention might be necessary to promote the recovery of the pre-disturbance state. We distinguish between helpful resilience, where resilience helps recovery, and unhelpful resilience where it does not, signalling the presence of a threshold and the need for intervention. Data to determine thresholds are not always available and so we consider the potential for indices of functional diversity to act as proxy measures of resilience. We also consider the contributions of connectivity and scale to resilience and how to incorporate these factors into management. We argue that linking thresholds to functional diversity indices may improve our ability to predict the resilience of ecosystems to future, potentially novel, disturbances according to their spatial and temporal scales of influence. Throughout, we provide guidance for the application of the resilience concept to ecosystem management. In doing so, we confirm its usefulness for improving biodiversity conservation in our rapidly changing world.}, journal={Biological Conservation}, publisher={Elsevier BV}, author={Standish, Rachel J. and Hobbs, Richard J. and Mayfield, Margaret M. and Bestelmeyer, Brandon T. and Suding, Katherine N. and Battaglia, Loretta L. and Eviner, Valerie and Hawkes, Christine V. and Temperton, Vicky M. and Cramer, Viki A. and et al.}, year={2014}, month={Sep}, pages={43–51} }
 @article{kardol_deyn_laliberté_mariotte_hawkes_2013, title={Biotic plant-soil feedbacks across temporal scales}, volume={101}, DOI={10.1111/1365-2745.12046}, abstractNote={Summary}, number={2}, journal={J Ecol}, publisher={Wiley-Blackwell}, author={Kardol, Paul and Deyn, Gerlinde B. De and Laliberté, Etienne and Mariotte, Pierre and Hawkes, Christine V.}, editor={Putten, WimEditor}, year={2013}, month={Feb}, pages={309–315} }
 @article{climate affects symbiotic fungal endophyte diversity and performance_2013, url={http://dx.doi.org/10.3732/ajb.1200568}, DOI={10.3732/ajb.1200568}, abstractNote={• Premise of the study: Fungal endophytes are symbionts that inhabit aboveground tissues of most terrestrial plants and can affect plant physiology and growth under stressed conditions. In a future faced with substantial climate change, endophytes have the potential to play an important role in plant stress resistance. Understanding both the distributions of endophytes and their functioning in symbiosis with plants are key aspects of predicting their role in an altered climate.}, journal={American Journal of Botany}, year={2013}, month={Jul} }
 @article{waring_averill_hawkes_2013, title={Differences in fungal and bacterial physiology alter soil carbon and nitrogen cycling: insights from meta-analysis and theoretical models}, volume={16}, DOI={10.1111/ele.12125}, abstractNote={Abstract}, number={7}, journal={Ecol Lett}, publisher={Wiley-Blackwell}, author={Waring, Bonnie G. and Averill, Colin and Hawkes, Christine V.}, editor={Holyoak, MarcelEditor}, year={2013}, month={May}, pages={887–894} }
 @article{aspinwall_lowry_taylor_juenger_hawkes_johnson_kiniry_fay_2013, title={Genotypic variation in traits linked to climate and aboveground productivity in a widespread C 4 grass: evidence for a functional trait syndrome}, volume={199}, DOI={10.1111/nph.12341}, abstractNote={Summary}, number={4}, journal={New Phytol}, publisher={Wiley-Blackwell}, author={Aspinwall, Michael J. and Lowry, David B. and Taylor, Samuel H. and Juenger, Thomas E. and Hawkes, Christine V. and Johnson, Mari-Vaughn V. and Kiniry, James R. and Fay, Philip A.}, year={2013}, month={May}, pages={966–980} }
 @article{perennial biomass grasses and the mason–dixon line: comparative productivity across latitudes in the southern great plains_2013, url={http://dx.doi.org/10.1007/s12155-012-9254-7}, DOI={10.1007/s12155-012-9254-7}, abstractNote={Understanding latitudinal adaptation of switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus × giganteus J. M. Greef & Deuter ex Hodk. & Renvoize) to the southern Great Plains is key to maximizing productivity by matching each grass variety to its optimal production environment. The objectives of this study were: (1) to quantify latitudinal variation in production of representative upland switchgrass ecotypes (Blackwell, Cave-in-Rock, and Shawnee), lowland switchgrass ecotypes (Alamo, Kanlow), and Miscanthus in the southern half of the US Great Plains and (2) to investigate the environmental factors affecting yield variation. Leaf area and yield were measured on plots at 10 locations in Missouri, Arkansas, Oklahoma, and Texas. More cold winter days led to decreased subsequent Alamo switchgrass yields and increased subsequent upland switchgrass yields. More hot-growing season days led to decreased Kanlow and Miscanthus yields. Increased drought intensity also contributed to decreased Miscanthus yields. Alamo switchgrass had the greatest radiation use efficiency (RUE) with a mean of 4.3 g per megajoule intercepted PAR and water use efficiency (WUE) with a mean of 4.5 mg of dry weight per gram of water transpired. The representative RUE values for other varieties ranged from 67 to 80 % of Alamo’s RUE value and 67 to 87 % of Alamo’s WUE. These results will provide valuable inputs to process-based models to realistically simulate these important perennial grasses in this region and to assess the environmental impacts of production on water use and nutrient demands. In addition, it will also be useful for landowners and companies choosing the most productive perennial grasses for biofuel production.}, journal={BioEnergy Research}, year={2013}, month={Mar} }
 @article{kivlin_waring_averill_hawkes_2013, title={Tradeoffs in microbial carbon allocation may mediate soil carbon storage in future climates}, volume={4}, DOI={10.3389/fmicb.2013.00261}, abstractNote={Climate-induced changes in soil microbial physiology impact ecosystem carbon (C) storage and alter the rate of CO2 flux from soils to the atmosphere (Allison et al., 2010). The direction and magnitude of these microbial feedbacks depend on changes in saprotrophic bacterial and fungal C allocation in response to altered temperature, precipitation, and nutrient availability. Soil microbes may differentially allocate C in changing environments by altering processes such as enzyme production, C use efficiency (CUE), or biomass stoichiometry (Figure ​(Figure1).1). However, because these mechanisms may operate simultaneously and interact, microbial physiological feedbacks on soil C storage are difficult to predict. For example, initial increases in microbial CUE or biomass C:N may be counteracted by increases in enzyme production to acquire limiting organic nutrients. 
 
 
 
Figure 1 
 
Three mechanisms through which microorganisms can shift C allocation: (A) extracellular enzyme activities, (B) carbon use efficiency, or (C) biomass stoichiometry. Each of these pathways can alter C storage in soils. Trend lines indicate expected responses ... 
 
 
 
Few studies have standardized microbial process rates, such as extracellular enzyme production or respiration, to the size of the microbial biomass. Examining process rates alone may obscure the microbial physiological mechanisms that underlie climate-induced changes in soil C cycling, leading to contradictory patterns among different studies. For instance, in a large-scale survey of soil protease activities from climate manipulations, drier and warmer conditions resulted in lower extracellular enzyme activities (EEA) compared to ambient conditions (Brzostek et al., 2012). In contrast, drier soils have also been found to stabilize extracellular enzymes in water films, reducing enzyme turnover rates and increasing potential activities (Lawrence et al., 2009; German et al., 2012).}, journal={Front. Microbiol.}, publisher={Frontiers Media SA}, author={Kivlin, Stephanie N. and Waring, Bonnie G. and Averill, Colin and Hawkes, Christine V.}, year={2013} }
 @article{hamman_hawkes_2012, title={Biogeochemical and Microbial Legacies of Non-Native Grasses Can Affect Restoration Success}, volume={21}, DOI={10.1111/j.1526-100x.2011.00856.x}, abstractNote={The restoration of disturbed ecosystems is challenging and often unsuccessful, particularly when non‐native plants are abundant. Ecosystem restoration may be hindered by the effects of non‐native plants on soil biogeochemical characteristics and microbial communities that persist even after plants are removed. To examine the importance of soil legacy effects, we used experimental restorations of Florida shrubland habitat that had been degraded by the introduction of non‐native grasses coupled with either mechanical disturbance or pasture conversion. We removed non‐native grasses and inoculated soils with native microbial communities at each degraded site, then examined how habitat structure, soil nitrogen, soil microbial abundances, and native seed germination responded over two years compared to undisturbed native sites. Grass removal treatments effectively restored some aspects of native habitat structure, including decreased exotic grass cover, increased bare ground, and reduced litter cover. Soil fungal abundance was also somewhat restored by grass removals, but soil algal abundance was unaffected. In addition, grass removal and microbial inoculation improved seed germination rates in degraded sites, but these remained quite low compared to native sites. High soil nitrogen persisted throughout the experiment regardless of treatment. Many treatment effects were site‐specific, however, with legacies in the more degraded vegetation type tending to be more difficult to overcome. These results support the need for context‐dependent restoration approaches and suggest that the degree of soil legacy effects may be a good indicator of restoration potential.}, number={1}, journal={Restoration Ecology}, publisher={Wiley-Blackwell}, author={Hamman, Sarah T. and Hawkes, Christine V.}, year={2012}, month={Apr}, pages={58–66} }
 @article{hawkes_kivlin_du_eviner_2012, title={The temporal development and additivity of plant-soil feedback in perennial grasses}, volume={369}, DOI={10.1007/s11104-012-1557-0}, number={1-2}, journal={Plant Soil}, publisher={Springer Science \mathplus Business Media}, author={Hawkes, Christine V. and Kivlin, Stephanie N. and Du, Jennifer and Eviner, Valerie T.}, year={2012}, pages={141–150} }
 @article{treseder_kivlin_hawkes_2011, title={Evolutionary trade-offs among decomposers determine responses to nitrogen enrichment}, volume={14}, DOI={10.1111/j.1461-0248.2011.01650.x}, abstractNote={ Ecology Letters (2011) 14: 933–938}, number={9}, journal={Ecology Letters}, publisher={Wiley-Blackwell}, author={Treseder, Kathleen K. and Kivlin, Stephanie N. and Hawkes, Christine V.}, year={2011}, month={Jul}, pages={933–938} }
 @article{kivlin_hawkes_treseder_2011, title={Global diversity and distribution of arbuscular mycorrhizal fungi}, volume={43}, DOI={10.1016/j.soilbio.2011.07.012}, abstractNote={Arbuscular mycorrhizal (AM) fungi form associations with most land plants and can control carbon, nitrogen, and phosphorus cycling between above- and belowground components of ecosystems. Current estimates of AM fungal distributions are mainly inferred from the individual distributions of plant biomes, and climatic factors. However, dispersal limitation, local environmental conditions,and interactions among AM fungal taxa may also determine local diversity and global distributions. We assessed the relative importance of these potential controls by collecting 14,961 DNA sequences from 111 published studies and testing for relationships between AM fungal community composition and geography, environment, and plant biomes. Our results indicated that the global species richness of AM fungi was up to six times higher than previously estimated, largely owing to high beta diversity among sampling sites. Geographic distance, soil temperature and moisture, and plant community type were each significantly related to AM fungal community structure, but explained only a small amount of the observed variance. AM fungal species also tended to be phylogenetically clustered within sites, further suggesting that habitat filtering or dispersal limitation is a driver of AM fungal community assembly. Therefore, predicted shifts in climate and plant species distributions under global change may alter AM fungal communities.}, number={11}, journal={Soil Biology and Biochemistry}, publisher={Elsevier BV}, author={Kivlin, Stephanie N. and Hawkes, Christine V. and Treseder, Kathleen K.}, year={2011}, month={Nov}, pages={2294–2303} }
 @article{kivlin_hawkes_2010, title={Differentiating between effects of invasion and diversity: impacts of aboveground plant communities on belowground fungal communities}, volume={189}, DOI={10.1111/j.1469-8137.2010.03494.x}, abstractNote={Exotic plant species can affect soil microbial communities with the potential for community and ecosystem feedbacks. Yet, separating the effects of exotics from confounded changes in plant community diversity still remains a challenge. We focused on how plant diversity and native or exotic life history affected root fungi because of their significant roles in community and ecosystem processes. Specifically, we examined how fungi colonizing plant roots were affected by plant richness (one, two or four species) replicated across a range of plant community mixtures (natives, exotics, native-exotic mixtures). Fungal biomass inside roots was affected independently by plant richness and mixture, while root fungal community composition was affected only by plant richness. Extraradical networks also increased in size with plant richness. By contrast, plant biomass was a function of plant mixture, with natives consistently smaller than exotics and native-exotic mixtures intermediate. Plant invasions may have an impact on the belowground community primarily through their effects on diversity, at least in the short-term. Disentangling the effects of diversity and invasion on belowground microbial communities can help us to understand both the controllers of belowground resilience and mechanisms of successful colonization and spread of exotic plants.}, number={2}, journal={New Phytologist}, publisher={Wiley-Blackwell}, author={Kivlin, Stephanie N. and Hawkes, Christine V.}, year={2010}, month={Oct}, pages={526–535} }
 @article{eviner_hoskinson_hawkes_2010, title={Ecosystem Impacts of Exotic Plants Can Feed Back to Increase Invasion in Western US Rangelands}, volume={32}, DOI={10.2111/rangelands-d-09-00005.1}, abstractNote={Ecosystem Impacts of Exotic Plants Can Feed Back to Increase Invasion in Western US Rangelands DOI:10.2458/azu_rangelands_v32i1_Hawkes}, number={1}, journal={Rangelands}, publisher={Elsevier BV}, author={Eviner, Valerie T. and Hoskinson, Sarah A. and Hawkes, Christine V.}, year={2010}, month={Feb}, pages={21–31} }
 @article{hawkes_kivlin_rocca_huguet_thomsen_suttle_2010, title={Fungal community responses to precipitation}, volume={17}, DOI={10.1111/j.1365-2486.2010.02327.x}, abstractNote={Understanding how fungal communities are affected by precipitation is an essential aspect of predicting soil functional responses to future climate change and the consequences of those responses for the soil carbon cycle. We tracked fungal abundance, fungal community composition, and soil carbon across 4 years in long‐term field manipulations of rainfall in northern California. Fungi responded directly to rainfall levels, with more abundant, diverse, and consistent communities predominating under drought conditions, and less abundant, less diverse, and more variable communities emerging during wetter periods and in rain‐addition treatments. Soil carbon storage itself did not vary with rainfall amendments, but increased decomposition rates foreshadow longer‐term losses of soil carbon under conditions of extended seasonal rainfall. The repeated recovery of fungal diversity and abundance during periodic drought events suggests that species with a wide range of environmental tolerances coexist in this community, consistent with a storage effect in soil fungi. Increased diversity during dry periods further suggests that drought stress moderates competition among fungal taxa. Based on the responses observed here, we suggest that there may be a relationship between the timescale at which soil microbial communities experience natural environmental fluctuations and their ability to respond to future environmental change.}, number={4}, journal={Global Change Biology}, publisher={Wiley-Blackwell}, author={HAWKES, CHRISTINE V. and KIVLIN, STEPHANIE N. and ROCCA, JENNIFER D. and HUGUET, VALERIE and THOMSEN, MEREDITH A. and SUTTLE, KENWYN BLAKE}, year={2010}, month={Oct}, pages={1637–1645} }
 @article{hausmann_hawkes_2010, title={Order of plant host establishment alters the composition of arbuscular mycorrhizal communities}, volume={91}, DOI={10.1890/09-0924.1}, abstractNote={The causes of local diversity and composition remain a central question in community ecology. Numerous studies have attempted to understand community assembly, both within and across trophic levels. However, little is known about how community assembly aboveground influences soil microbial communities belowground. We hypothesized that plant establishment order can affect the community of arbuscular mycorrhizal fungi (AMF) in roots, with the strength of this effect dependent on both host plant identity and neighboring plant identity. Such priority effects of plants on AMF may act through host‐specific filters of the initial species pool that limit the available pool for plants that established second. In a greenhouse experiment with four plant hosts, we found that the strength of the priority effect on AMF communities reflected both host plant characteristics and interactions between host and neighbor plant species, consistent with differential host specificity among plants. These patterns were independent of plant biomass and root colonization. Functional studies of AMF associated with a wide array of host plants will be required to further understand this potential driver of community dynamics.}, number={8}, journal={Ecology}, publisher={Ecological Society of America}, author={Hausmann, Natasha Teutsch and Hawkes, Christine V.}, year={2010}, month={Aug}, pages={2333–2343} }
 @article{hawkes_douglas_fitter_2009, title={Origin, local experience, and the impact of biotic interactions on native and introduced Senecio species}, volume={12}, DOI={10.1007/s10530-009-9435-2}, number={1}, journal={Biol Invasions}, publisher={Springer Science \mathplus Business Media}, author={Hawkes, Christine V. and Douglas, Angela E. and Fitter, Alastair H.}, year={2009}, month={Feb}, pages={113–124} }
 @article{hausmann_hawkes_2009, title={Plant neighborhood control of arbuscular mycorrhizal community composition}, volume={183}, DOI={10.1111/j.1469-8137.2009.02882.x}, abstractNote={Arbuscular mycorrhizal fungi (AMF) are important root symbionts that can provide benefits to plant hosts, yet we understand little about how neighboring hosts in a plant community contribute to the composition of the AMF community. We hypothesized that the composition of the plant neighborhood, including the identities of both host and neighbor, would alter AMF community composition. We tested this in a glasshouse experiment in which a native perennial grass (Nassella pulchra) and three annual grasses (Avena barbata, Bromus hordeaceaous and Vulpia microstachys) were grown in two neighborhoods: conspecific monocultures and heterospecific perennial-annual mixtures. To identify AMF taxa colonizing plant roots, we used a combination of terminal restriction fragment length polymorphism and cloning. Both host and neighbor were important in structuring AMF communities. Unique AMF communities were associated with each plant host in monoculture. In heterospecific neighborhoods, the annual neighbors V. microstachys, A. barbata, and B. hordeaceus influenced N. pulchra AMF in different ways (synergistic, controlling, or neutral) and the reciprocal effect was not always symmetric. Our findings support a community approach to AMF studies, which can be used to increase our understanding of processes such as invasion and succession.}, number={4}, journal={New Phytologist}, publisher={Wiley-Blackwell}, author={Hausmann, Natasha Teutsch and Hawkes, Christine V.}, year={2009}, month={Sep}, pages={1188–1200} }
 @article{fox_kareiva_silliman_hitt_lytle_halpern_hawkes_lawler_neel_olden_et al._2009, title={Why do we fly? Ecologists' sins of emission}, volume={7}, DOI={10.1890/09.wb.019}, abstractNote={Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.}, number={6}, journal={Frontiers in Ecology and the Environment}, publisher={Ecological Society of America}, author={Fox, Helen E and Kareiva, Peter and Silliman, Brian and Hitt, Jessica and Lytle, David A and Halpern, Benjamin S and Hawkes, Christine V and Lawler, Joshua and Neel, Maile and Olden, Julian D and et al.}, year={2009}, month={Aug}, pages={294–296} }
 @article{eviner_hawkes_2008, title={Embracing Variability in the Application of Plant-Soil Interactions to the Restoration of Communities and Ecosystems}, volume={16}, DOI={10.1111/j.1526-100x.2008.00482.x}, abstractNote={Abstract}, number={4}, journal={Restoration Ecology}, publisher={Wiley-Blackwell}, author={Eviner, Valerie T. and Hawkes, Christine V.}, year={2008}, pages={713–729} }
 @article{preserving accuracy in genbank_2008, url={http://dx.doi.org/10.1126/science.319.5870.1616a}, DOI={10.1126/science.319.5870.1616a}, abstractNote={GenBank, the public repository for nucleotide and protein sequences, is a critical resource for molecular biology, evolutionary biology, and ecology. While some attention has been drawn to sequence errors ([1][1]), common annotation errors also reduce the value of this database. In fact, for}, journal={Science}, year={2008}, month={Mar} }
 @article{hawkes_hartley_ineson_fitter_2008, title={Soil temperature affects carbon allocation within arbuscular mycorrhizal networks and carbon transport from plant to fungus}, volume={14}, DOI={10.1111/j.1365-2486.2007.01535.x}, abstractNote={Abstract}, number={5}, journal={Global Change Biol}, publisher={Wiley-Blackwell}, author={HAWKES, CHRISTINE V. and HARTLEY, IAIN P. and INESON, PHIL and FITTER, ALASTAIR H.}, year={2008}, month={May}, pages={1181–1190} }
 @article{hawkes_2007, title={Are Invaders Moving Targets? The Generality and Persistence of Advantages in Size, Reproduction, and Enemy Release in Invasive Plant Species with Time since Introduction}, volume={170}, DOI={10.1086/522842}, abstractNote={Successful plant invasions are often attributed to increased plant size, reproduction, or release from natural enemies, but the generality and persistence of these patterns remains widely debated. Meta‐analysis was used to quantitatively assess invasive plant performance and release from enemy damage and how these change with residence time and geographic distribution. Invasive plants were compared either in their introduced and home ranges or with native congeners in the introduced range. Invasive plants in the introduced range were generally larger, allocated more to reproduction, and had lower levels of herbivore damage compared with conspecifics in the home range; pathogen attack, however, varied widely. In congener comparisons, invasive and native plants did not differ in size or herbivory, but invaders did allocate less to reproduction and had lower levels of pathogen damage. Time since introduction was a significant nonlinear predictor of enemy release for both herbivores and pathogens, with initial release in recently arrived species and little to no release after 50 to 200 years. Geographic distribution was also a significant nonlinear predictor of enemy release. The observed nonlinear relationships are consistent with dynamic invasions and may define targets for eradication efforts if these patterns hold up for individual species.}, number={6}, journal={Am Nat}, publisher={University of Chicago Press}, author={Hawkes, Christine V.}, year={2007}, pages={832–843} }
 @article{hawkes_deangelis_firestone_2007, title={Root Interactions with Soil Microbial Communities and Processes}, DOI={10.1016/b978-012088775-0/50003-3}, abstractNote={Publisher Summary This chapter discusses the recent advances in rhizosphere microbial ecology, the impacts of rhizosphere microbial communities on nutrient cycling, and the importance of rhizosphere processes at larger scales. A common definition of soil is the surface layer of earth that supports plant life. Rhizosphere soil effectively forms a boundary layer between the roots and the surrounding soil. Plant roots grow into and through an extraordinary array of “indigenous” soil microorganisms. Community characterization is not always genotypic in nature, but may occur at different scales ranging from functional diversity to broader taxons to simple abundance. Functional diversity can also be estimated by measuring functional genes that play a role in ecosystem processes. In 16S rDNA analysis of the rhizosphere microbial community, phylogenetic diversity can be related to function only through conventional interpretations. Root-microbial interactions encompass a range of specificity from “highly evolved” symbioses (legume-rhizobium) to less specific associations (arbuscular mycorrhizas). Apparent symbioses are the most likely to develop host-specificity. Plant roots exude a large amount and a complex assortment of organic compounds into the nearby soil. A variety of biotic interactions occur in the rhizosphere that can affect the diversity and composition of the microbial community associated with roots. Global changes in climate and plant communities may further alter microbial communities with consequences for ecosystem process rates. Research since the 1990s has underscored the fact that understanding and quantifying the interactions among plants and soil microbes is essential for understanding both plant and soil microbial community ecology and the roles that these communities play in ecosystem function.}, journal={The Rhizosphere}, publisher={Elsevier BV}, author={Hawkes, Christine V. and DeAngelis, Kristen M. and Firestone, Mary K.}, year={2007}, pages={1–29} }
 @article{hawkes_belnap_carla_firestone_2006, title={Arbuscular Mycorrhizal Assemblages in Native Plant Roots Change in the Presence of Invasive Exotic Grasses}, volume={281}, DOI={10.1007/s11104-005-4826-3}, number={1-2}, journal={Plant Soil}, publisher={Springer Science \mathplus Business Media}, author={Hawkes, Christine V. and Belnap, Jayne and Carla, D’Antonio and Firestone, Mary K.}, year={2006}, month={Mar}, pages={369–380} }
 @article{hawkes_wren_herman_firestone_2005, title={Plant invasion alters nitrogen cycling by modifying the soil nitrifying community}, volume={8}, DOI={10.1111/j.1461-0248.2005.00802.x}, abstractNote={Abstract}, number={9}, journal={Ecol Letters}, publisher={Wiley-Blackwell}, author={Hawkes, Christine V. and Wren, Ian F. and Herman, Donald J. and Firestone, Mary K.}, year={2005}, month={Sep}, pages={976–985} }
 @article{hawkes_2004, title={Effects of biological soil crusts on seed germination of four endangered herbs in a xeric Florida shrubland during drought}, volume={170}, DOI={10.1023/b:vege.0000019035.56245.91}, number={1}, journal={Plant Ecology}, publisher={Springer Science \mathplus Business Media}, author={Hawkes, Christine V.}, year={2004}, pages={121–134} }
 @article{hawkes_sullivan_2001, title={The Impact of Herbivory on Plants in Different Resource Conditions: A Meta-Analysis}, volume={82}, DOI={10.2307/2680068}, abstractNote={Understanding how plant recovery from herbivory interacts with the resource environment is necessary to predict under what resource conditions plants are most affected by herbivory, and ultimately how herbivory impacts plant population dynamics. It has been commonly assumed that plants are generally best able to recover from herbivory when growing in high resource conditions, an assumption which is supported by some models (e.g., the continuum of responses model) but opposed by others (e.g., the growth rate model). The validity and generality of any effects of resources (light, nutrients, and water) on plant recovery from herbivory were tested with mixed-model, factorial meta-analyses using a log response ratio metric applied to plant growth and reproduction data from the ecological literature. In total, 81 records from 45 studies were included in the growth meta-analysis, and 24 records from 14 studies in the reproduction meta-analysis. High resource levels and the absence of herbivory both strongly increased plant growth and reproduction. There was no significant overall interaction between growth or reproduction after herbivory and resource conditions, but the interaction terms were significant for each plant functional group in the growth meta-analysis. Basal meristem monocots grew significantly more after herbivory in high resources, while both dicot herbs and woody plants grew significantly more after herbivory in low resources. A similar result was found in the 34.6% of growth records where exact- or overcompensation occurred. Overcompensation was more likely in high resources for monocots and in low resources for dicot herbs. The reproduction data set was too small to subdivide. These qualitative differences between monocot and dicot herbs and woody plants explain many of the contradictory results in the literature and show that no single current model can account for the responses of all plants to herbivory.}, number={7}, journal={Ecology}, publisher={JSTOR}, author={Hawkes, Christine V. and Sullivan, Jon J.}, year={2001}, month={Jul}, pages={2045} }
 @article{hawkes_menges_1996, title={The Relationship between Open Space and Fire for Species in a Xeric Florida Shrubland}, volume={123}, DOI={10.2307/2996065}, number={2}, journal={Bulletin of the Torrey Botanical Club}, publisher={JSTOR}, author={Hawkes, Christine V. and Menges, Eric S.}, year={1996}, month={Apr}, pages={81} }
 @article{hawkes_menges_1995, title={Density and Seed Production of a Florida Endemic, Polygonella basiramia, in Relation to Time since Fire and Open Sand}, volume={133}, DOI={10.2307/2426355}, abstractNote={-Density and reproductive output in relation to fire, open sand, and other site factors were determined for Polygonella basiramia. This federally endangered species is endemic to only three ridges in central Florida and found primarily in rosemary (Ceratiola ericoides) dominated sand pine (Pinus clausa) scrub. Twenty-two sites ranging from 5 to >26 yr postfire were sampled. Site factors of openness, time since last fire, dominant species, ground cover, elevation and soil type were examined. Multivariate analyses identified the amount of open sand habitat at a site as the only variable having a significant positive relationship with both plant density and seed production. Seed production actually increased with conspecific density, suggesting that the lack of interspecific competition in open sand gaps helps define P basiramia microhabitat. Open sand habitat is critical in the life history strategy of this obligate-seeding, perennial herb in a community where it must compete with larger, resprouting shrubs and herbs both immediately after fire and during fire-free inter-}, number={1}, journal={American Midland Naturalist}, publisher={JSTOR}, author={Hawkes, Christine V. and Menges, Eric S.}, year={1995}, month={Jan}, pages={138} }