@article{gao_mcgregor_gray_friedl_moon_2023, title={Observations of Satellite Land Surface Phenology Indicate That Maximum Leaf Greenness Is More Associated With Global Vegetation Productivity Than Growing Season Length}, volume={37}, ISSN={["1944-9224"]}, url={https://doi.org/10.1029/2022GB007462}, DOI={10.1029/2022GB007462}, abstractNote={Vegetation green leaf phenology directly impacts gross primary productivity (GPP) of terrestrial ecosystems. Satellite observations of land surface phenology (LSP) provide an important means to monitor the key timing of vegetation green leaf development. However, differences between satellite‐derived LSP proxies and in situ measurements of GPP make it difficult to quantify the impact of climate‐induced changes in green leaf phenology on annual GPP. Here, we used 1,110 site‐years of GPP measurements from eddy‐covariance towers in association with time series of satellite LSP observations from 2000 to 2014 to show that while satellite LSP explains a large proportion of variation in annual GPP, changes in green‐leaf‐based growing season length (GSL, leaf development period from spring to autumn) had less impact on annual GPP by ∼30% than GSL changes in GPP‐based photosynthetic duration. Further, maximum leaf greenness explained substantially more variance in annual GPP than green leaf GSL, highlighting the role of future vegetation greening trends on large‐scale carbon budgets. Site‐level variability contributes a substantial proportion of annual GPP variance in the model based on LSP metrics, suggesting the importance of local environmental factors altering regional GPP. We conclude that satellite LSP‐based inferences regarding large‐scale dynamics in GPP need to consider changes in both green leaf GSL and maximum greenness.}, number={3}, journal={GLOBAL BIOGEOCHEMICAL CYCLES}, author={Gao, Xiaojie and McGregor, Ian R. R. and Gray, Josh M. M. and Friedl, Mark A. A. and Moon, Minkyu}, year={2023}, month={Mar} }
 @misc{vinod_slot_mcgregor_ordway_smith_taylor_sack_buckley_anderson-teixeira_2023, title={Thermal sensitivity across forest vertical profiles: patterns, mechanisms, and ecological implications}, volume={237}, ISSN={["1469-8137"]}, url={https://doi.org/10.1111/nph.18539}, DOI={10.1111/nph.18539}, abstractNote={Rising temperatures are influencing forests on many scales, with potentially strong variation vertically across forest strata. Using published research and new analyses, we evaluate how microclimate and leaf temperatures, traits, and gas exchange vary vertically in forests, shaping tree and ecosystem ecology. In closed-canopy forests, upper-canopy leaves are exposed to the highest solar radiation and evaporative demand, which can elevate leaf temperature (Tleaf ), particularly when transpirational cooling is curtailed by limited stomatal conductance. However, foliar traits also vary across height or light gradients, partially mitigating and protecting against the elevation of upper-canopy Tleaf . Leaf metabolism generally increases with height across the vertical gradient, yet differences in thermal sensitivity across the gradient appear modest. Scaling from leaves to trees, canopy trees have higher absolute metabolic capacity and growth, yet are more vulnerable to drought and damaging Tleaf than their smaller counterparts, particularly under climate change. In contrast, understory trees experience fewer extreme high Tleaf 's but have fewer cooling mechanisms and thus may be strongly impacted by warming under some conditions, particularly when exposed to a harsher microenvironment through canopy disturbance. As the climate changes, integrating the patterns and mechanisms reviewed here into models will be critical to forecasting forest-climate feedbacks.}, number={1}, journal={NEW PHYTOLOGIST}, author={Vinod, Nidhi and Slot, Martijn and McGregor, Ian R. and Ordway, Elsa M. and Smith, Marielle N. and Taylor, Tyeen C. and Sack, Lawren and Buckley, Thomas N. and Anderson-Teixeira, Kristina J.}, year={2023}, month={Jan}, pages={22–47} }
 @article{kim_herrmann_bareto_calkins_gonzalez-akre_johnson_jordan_magee_mcgregor_montero_et al._2022, title={Implementing GitHub Actions continuous integration to reduce error rates in ecological data collection}, volume={9}, ISSN={["2041-2096"]}, url={https://doi.org/10.1111/2041-210X.13982}, DOI={10.1111/2041-210X.13982}, abstractNote={Accurate field data are essential to understanding ecological systems and forecasting their responses to global change. Yet, data collection errors are common, and data analysis often lags far enough behind its collection that many errors can no longer be corrected, nor can anomalous observations be revisited. Needed is a system in which data quality assurance and control (QA/QC), along with the production of basic data summaries, can be automated immediately following data collection. Here, we implement and test a system to satisfy these needs. For two annual tree mortality censuses and a dendrometer band survey at two forest research sites, we used GitHub Actions continuous integration (CI) to automate data QA/QC and run routine data wrangling scripts to produce cleaned datasets ready for analysis. This system automation had numerous benefits, including (1) the production of near real‐time information on data collection status and errors requiring correction, resulting in final datasets free of detectable errors, (2) an apparent learning effect among field technicians, wherein original error rates in field data collection declined significantly following implementation of the system, and (3) an assurance of computational reproducibility—that is, robustness of the system to changes in code, data and software. By implementing CI, researchers can ensure that datasets are free of any errors for which a test can be coded. The result is dramatically improved data quality, increased skill among field technicians, and reduced need for expert oversight. Furthermore, we view CI implementation as a first step towards a data collection and analysis pipeline that is also more responsive to rapidly changing ecological dynamics, making it better suited to study ecological systems in the current era of rapid environmental change.}, journal={METHODS IN ECOLOGY AND EVOLUTION}, author={Kim, Albert Y. and Herrmann, Valentine and Bareto, Ross and Calkins, Brianna and Gonzalez-Akre, Erika and Johnson, Daniel J. and Jordan, Jennifer A. and Magee, Lukas and McGregor, Ian R. and Montero, Nicolle and et al.}, year={2022}, month={Sep} }
 @book{gao_mcgregor_smith_hinks_shisler_2022, title={The blsp R package with a Bayesian land surface phenology model}, DOI={10.5281/zenodo.6824017}, institution={Zenodo}, author={Gao, X. and McGregor, I.R. and Smith, O. and Hinks, I. and Shisler, M.}, year={2022} }
 @article{dow_kim_d’orangeville_gonzalez-akre_helcoski_herrmann_harley_maxwell_mcgregor_mcshea_et al._2022, title={Warm springs alter timing but not total growth of temperate deciduous trees}, volume={608}, ISSN={["1476-4687"]}, DOI={10.1038/s41586-022-05092-3}, abstractNote={As the climate changes, warmer spring temperatures are causing earlier leaf-out1-3 and commencement of CO2 uptake1,3 in temperate deciduous forests, resulting in a tendency towards increased growing season length3 and annual CO2 uptake1,3-7. However, less is known about how spring temperatures affect tree stem growth8,9, which sequesters carbon in wood that has a long residence time in the ecosystem10,11. Here we show that warmer spring temperatures shifted stem diameter growth of deciduous trees earlier but had no consistent effect on peak growing season length, maximum growth rates, or annual growth, using dendrometer band measurements from 440 trees across two forests. The latter finding was confirmed on the centennial scale by 207 tree-ring chronologies from 108 forests across eastern North America, where annual ring width was far more sensitive to temperatures during the peak growing season than in the spring. These findings imply that any extra CO2 uptake in years with warmer spring temperatures4,5 does not significantly contribute to increased sequestration in long-lived woody stem biomass. Rather, contradicting projections from global carbon cycle models1,12, our empirical results imply that warming spring temperatures are unlikely to increase woody productivity enough to strengthen the long-term CO2 sink of temperate deciduous forests.}, journal={Nature}, author={Dow, C. and Kim, A.Y. and D’Orangeville, L. and Gonzalez-Akre, E.B. and Helcoski, R. and Herrmann, V. and Harley, G.L. and Maxwell, J.T. and McGregor, I.R. and McShea, W.J. and et al.}, year={2022}, pages={552–557} }
 @article{chemical similarity of co-occurring trees decreases with precipitation and temperature in north american forests_2021, volume={9}, url={http://dx.doi.org/10.3389/fevo.2021.679638}, DOI={10.3389/fevo.2021.679638}, abstractNote={Plant diversity varies immensely over large-scale gradients in temperature, precipitation, and seasonality at global and regional scales. This relationship may be driven in part by climatic variation in the relative importance of abiotic and biotic interactions to the diversity and composition of plant communities. In particular, biotic interactions may become stronger and more host specific with increasing precipitation and temperature, resulting in greater plant species richness in wetter and warmer environments. This hypothesis predicts that the many defensive compounds found in plants’ metabolomes should increase in richness and decrease in interspecific similarity with precipitation, temperature, and plant diversity. To test this prediction, we compared patterns of chemical and morphological trait diversity of 140 woody plant species among seven temperate forests in North America representing 16.2°C variation in mean annual temperature (MAT), 2,115 mm variation in mean annual precipitation (MAP), and from 10 to 68 co-occurring species. We used untargeted metabolomics methods based on data generated with liquid chromatography-tandem mass spectrometry to identify, classify, and compare 13,480 unique foliar metabolites and to quantify the metabolomic similarity of species in each community with respect to the whole metabolome and each of five broad classes of metabolites. In addition, we compiled morphological trait data from existing databases and field surveys for three commonly measured traits (specific leaf area [SLA], wood density, and seed mass) for comparison with foliar metabolomes. We found that chemical defense strategies and growth and allocation strategies reflected by these traits largely represented orthogonal axes of variation. In addition, functional dispersion of SLA increased with MAP, whereas functional richness of wood density and seed mass increased with MAT. In contrast, chemical similarity of co-occurring species decreased with both MAT and MAP, and metabolite richness increased with MAT. Variation in metabolite richness among communities was positively correlated with species richness, but variation in mean chemical similarity was not. Our results are consistent with the hypothesis that plant metabolomes play a more important role in community assembly in wetter and warmer climates, even at temperate latitudes, and suggest that metabolomic traits can provide unique insight to studies of trait-based community assembly.}, journal={Frontiers in Ecology and Evolution}, publisher={Frontiers Media SA}, year={2021}, month={May} }
 @article{mcgregor_helcoski_kunert_tepley_gonzalez‐akre_herrmann_zailaa_stovall_bourg_mcshea_et al._2021, title={Tree height and leaf drought tolerance traits shape growth responses across droughts in a temperate broadleaf forest}, volume={10}, url={https://doi.org/10.1111/nph.16996}, DOI={10.1111/nph.16996}, abstractNote={As climate change drives increased drought in many forested regions, mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. The dendrochronological record provides a window through which we can understand how tree size and traits shape growth responses to droughts. We analyzed tree-ring records for twelve species in a broadleaf deciduous forest in Virginia (USA) to test hypotheses for how tree height, microenvironment characteristics, and species' traits shaped drought responses across the three strongest regional droughts over a 60-year period. Drought tolerance (resistance, recovery, and resilience) decreased with tree height, which was strongly correlated with exposure to higher solar radiation and evaporative demand. The potentially greater rooting volume of larger trees did not confer a resistance advantage, but marginally increased recovery and resilience, in sites with low topographic wetness index. Drought tolerance was greater among species whose leaves lost turgor (wilted) at more negative water potentials and experienced less shrinkage upon desiccation. The tree-ring record reveals that tree height and leaf drought tolerance traits influenced growth responses during and after significant droughts in the meteorological record. As climate change-induced droughts intensify, tall trees with drought-sensitive leaves will be most vulnerable to immediate and longer-term growth reductions.}, journal={New Phytologist}, publisher={Wiley}, author={McGregor, Ian R. and Helcoski, Ryan and Kunert, Norbert and Tepley, Alan J. and Gonzalez‐Akre, Erika B. and Herrmann, Valentine and Zailaa, Joseph and Stovall, Atticus E. L. and Bourg, Norman A. and McShea, William J. and et al.}, year={2021}, month={Jul} }
 @article{yoshizumi_coffer_collins_gaines_gao_jones_mcgregor_mcquillan_perin_tomkins_et al._2020, title={A Review of Geospatial Content in IEEE Visualization Publications}, DOI={10.1109/VIS47514.2020.00017}, abstractNote={Geospatial analysis is crucial for addressing many of the world’s most pressing challenges. Given this, there is immense value in improving and expanding the visualization techniques used to communicate geospatial data. In this work, we explore this important intersection – between geospatial analytics and visualization – by examining a set of recent IEEE VIS Conference papers (a selection from 2017-2019) to assess the inclusion of geospatial data and geospatial analyses within these papers. After removing the papers with no geospatial data, we organize the remaining literature into geospatial data domain categories and provide insight into how these categories relate to VIS Conference paper types. We also contextualize our results by investigating the use of geospatial terms in IEEE Visualization publications over the last 30 years. Our work provides an understanding of the quantity and role of geospatial subject matter in recent IEEE VIS publications and supplies a foundation for future meta-analytical work around geospatial analytics and geovisualization that may shed light on opportunities for innovation.}, journal={2020 IEEE VISUALIZATION CONFERENCE - SHORT PAPERS (VIS 2020)}, author={Yoshizumi, Alexander and Coffer, Megan M. and Collins, Elyssa L. and Gaines, Mollie D. and Gao, Xiaojie and Jones, Kate and McGregor, Ian R. and McQuillan, Katie A. and Perin, Vinicius and Tomkins, Laura M. and et al.}, year={2020}, pages={51–55} }
 @article{a review of geospatial content in ieee visualization publications_2020, url={https://arxiv.org/pdf/2009.03390.pdf}, year={2020}, month={Sep} }
 @article{long-term impacts of invasive insects and pathogens on composition, biomass, and diversity of forests in virginia’s blue ridge mountains_2020, url={http://dx.doi.org/10.1007/s10021-020-00503-w}, DOI={10.1007/s10021-020-00503-w}, journal={Ecosystems}, year={2020}, month={Apr} }
 @misc{scbi-forestgeo/scbi-forestgeo-data: 2020 update_2020, url={https://zenodo.org/record/4041595}, DOI={10.5281/ZENODO.4041595}, year={2020}, month={Sep} }
 @misc{forestgeo/climate: initial release_2020, url={https://zenodo.org/record/4041609}, DOI={10.5281/ZENODO.4041609}, year={2020}, month={Sep} }
 @article{cardoso_oliveras_abernethy_jeffery_lehmann_ndong_mcgregor_belcher_bond_malhi_2018, title={Grass Species Flammability, Not Biomass, Drives Changes in Fire Behavior at Tropical Forest-Savanna Transitions}, volume={1}, DOI={10.3389/ffgc.2018.00006}, abstractNote={Forest-savanna mosaics are maintained by fire-mediated positive feedbacks; whereby forest is fire suppressive and savanna is fire promoting. Forest-savanna transitions therefore represent the interface of opposing fire regimes. Within the transition there is a threshold point at which tree canopy cover becomes sufficiently dense to shade out grasses and thus suppress fire. Prior to reaching this threshold, changes in fire behaviour may already be occurring within the savanna. Such changes are neither empirically described nor their drivers understood. Fire behaviour is largely driven by fuel flammability. Flammability can vary significantly between grass species and grass species composition can change near forest-savanna transitions. This study measured fire behaviour changes at eighteen forest-savanna transition sites in a vegetation mosaic in Lope National Park in Gabon, central Africa. The extent to which these changes could be attributed to changes in grass flammability was determined using species-specific flammability traits. Results showed simultaneous suppression of fire and grass biomass when tree canopy leaf area index (LAI) reached a value of 3, indicating that a fire suppression threshold existed within the forest-savanna transition. Fires became less intense and less hot prior to reaching this fire suppression threshold. These changes were associated with higher LAI values, which induced a change in the grass community, from one dominated by the highly flammable Anadelphia afzeliana to one dominated by the less flammable Hyparrhenia diplandra. Changes in fire behaviour were not associated with changes in total grass biomass. This study demonstrated not only the presence of a fire suppression threshold but the mechanism of its action. Grass composition mediated fire-behaviour within the savanna prior to reaching the suppression threshold, and grass species composition was mediated by tree canopy cover which was in turn mediated by fire-behaviour. These findings highlight how biotic and abiotic controls interact and amplify each other in this mosaicked landscape to facilitate forest and savanna co-existence.}, journal={Frontiers in Forests and Global Change}, publisher={Frontiers Media SA}, author={Cardoso, Anabelle W. and Oliveras, Imma and Abernethy, Katharine A. and Jeffery, Kathryn J. and Lehmann, David and Ndong, Josué Edzang and McGregor, Ian and Belcher, Claire M. and Bond, William J. and Malhi, Yadvinder S.}, year={2018}, month={Nov} }