@article{gotsch_geiger_franco_goldstein_meinzer_hoffmann_2019, title={Allocation to leaf area and sapwood area affects water relations of co-occurring savanna and forest trees (vol 163, pg 291, 2010)}, volume={189}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-018-04327-3}, abstractNote={The original version of this article unfortunately contained a mistake. The Electronic supplementary material (ESM) was accompanying this article by mistake.}, number={2}, journal={OECOLOGIA}, author={Gotsch, Sybil G. and Geiger, Erika L. and Franco, Augusto C. and Goldstein, Guillermo and Meinzer, Frederick C. and Hoffmann, William A.}, year={2019}, month={Feb}, pages={563–563} }
 @misc{hoffmann_geiger_gotsch_rossatto_silva_lau_haridasan_franco_2012, title={Ecological thresholds at the savanna-forest boundary: how plant traits, resources and fire govern the distribution of tropical biomes}, volume={15}, ISSN={["1461-0248"]}, DOI={10.1111/j.1461-0248.2012.01789.x}, abstractNote={AbstractFire shapes the distribution of savanna and forest through complex interactions involving climate, resources and species traits. Based on data from central Brazil, we propose that these interactions are governed by two critical thresholds. The fire‐resistance threshold is reached when individual trees have accumulated sufficient bark to avoid stem death, whereas the fire‐suppression threshold is reached when an ecosystem has sufficient canopy cover to suppress fire by excluding grasses. Surpassing either threshold is dependent upon long fire‐free intervals, which are rare in mesic savanna. On high‐resource sites, the thresholds are reached quickly, increasing the probability that savanna switches to forest, whereas low‐resource sites are likely to remain as savanna even if fire is infrequent. Species traits influence both thresholds; saplings of savanna trees accumulate bark thickness more quickly than forest trees, and are more likely to become fire resistant during fire‐free intervals. Forest trees accumulate leaf area more rapidly than savanna trees, thereby accelerating the transition to forest. Thus, multiple factors interact with fire to determine the distribution of savanna and forest by influencing the time needed to reach these thresholds. Future work should decipher multiple environmental controls over the rates of tree growth and canopy closure in savanna.}, number={7}, journal={ECOLOGY LETTERS}, author={Hoffmann, William A. and Geiger, Erika L. and Gotsch, Sybil G. and Rossatto, Davi R. and Silva, Lucas C. R. and Lau, On Lee and Haridasan, M. and Franco, Augusto C.}, year={2012}, month={Jul}, pages={759–768} }
 @article{geiger_gotsch_damasco_haridasan_franco_hoffmann_2011, title={Distinct roles of savanna and forest tree species in regeneration under fire suppression in a Brazilian savanna}, volume={22}, ISSN={["1654-1103"]}, DOI={10.1111/j.1654-1103.2011.01252.x}, abstractNote={Questions: Has fire suppression relaxed barriers to the exchange of species between savanna and forest? Do all species or a subset of species participate in this exchange? Would current vegetation structure persist if fire suppression were to cease? Location: A gallery forest edge in the Cerrado region of central Brazil that burned only once in the past 35 years. Methods: Density of tree seedlings, saplings and adults, leaf area index (LAI), tree basal area and diameter were surveyed in 12, 10m � 70m transects centred on and perpendicular to the forest‐savanna boundary. Community composition was assessed using non-metric multi-dimensional scaling (NMDS). Results: Basal area and LAI declined substantially from forest to savanna, with an associated shift in species composition. Savanna tree species were nearly absent in the forest, but accounted for the majority of stems in the savanna. In contrast, forest species comprised 14% of adults and more than one-third of juveniles in the savanna. Despite the high diversity of trees (85 species) in the forest, five species play a particularly large role in this initial phase of forest expansion. Reintroduction of fire, however, would result in widespread topkill of juveniles and the majority of adult forest trees, thereby interrupting the succession towards forest. Conclusions: After 35 years during which the site burned only once, the savanna still remains dominated by savanna species. Nevertheless, the dominance of forest juveniles in border and savanna tree communities suggests that with a continued policy of fire suppression, the forest will continue to expand.}, number={2}, journal={JOURNAL OF VEGETATION SCIENCE}, author={Geiger, Erika L. and Gotsch, Sybil G. and Damasco, Gabriel and Haridasan, M. and Franco, Augusto C. and Hoffmann, William A.}, year={2011}, month={Apr}, pages={312–321} }
 @article{hoffmann_jaconis_mckinley_geiger_gotsch_franco_2012, title={Fuels or microclimate? Understanding the drivers of fire feedbacks at savanna-forest boundaries}, volume={37}, ISSN={["1442-9985"]}, DOI={10.1111/j.1442-9993.2011.02324.x}, abstractNote={AbstractThe higher flammability of tropical savanna, compared with forest, plays a critical role in mediating vegetation‐environment feedbacks, alternate stable states, and ultimately, the distribution of these two biomes. Multiple factors contribute to this difference in flammability, including microclimate, fuel amount and fuel type. To understand this transition in flammability, we studied fuel characteristics and microclimate across eight savanna–forest boundaries in south‐central Brazil. At each boundary, the environment was monitored for one week with automated measurements of near‐surface wind speed, air temperature, relative humidity and presence of dew. Manual measurements were performed to quantify fuel amounts and fuel moisture. These data were used to parameterize the fire behaviour model BehavePlus5 in order to simulate fire behaviour over the savanna–forest boundary. There were strong gradients across the boundary in all variables with the exception of total fuel load. During the day, savannas had higher wind speed and air temperature, and lower relative humidity and fuel moisture than forests. Although fuel loads were similar in savanna and forest, savanna was characterized by lower fuel bulk density, largely because of the presence of grasses. Based on these measurements, the fire behaviour model predicted savanna fires to be faster, more intense, and with greater flame lengths, relative to forest. A sensitivity analysis indicated that the primary cause of these differences was the low fuel bulk density characteristic of grassy fuels, with lesser contributions from wind speed, fuel moisture and total fuel load. These results indicate that the dominance of grassy fuels is the primary cause of the high flammability of savanna.}, number={6}, journal={AUSTRAL ECOLOGY}, author={Hoffmann, William A. and Jaconis, Susany. and Mckinley, Kristen L. and Geiger, Erika L. and Gotsch, Sybil G. and Franco, Augusto C.}, year={2012}, month={Sep}, pages={634–643} }
 @article{gotsch_geiger_franco_goldstein_meinzer_hoffmann_2010, title={Allocation to leaf area and sapwood area affects water relations of co-occurring savanna and forest trees}, volume={163}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-009-1543-2}, abstractNote={Water availability is a principal factor limiting the distribution of closed-canopy forest in the seasonal tropics, suggesting that forest tree species may not be well adapted to cope with seasonal drought. We studied 11 congeneric species pairs, each containing one forest and one savanna species, to test the hypothesis that forest trees have a lower capacity to maintain seasonal homeostasis in water relations relative to savanna species. To quantify this, we measured sap flow, leaf water potential (ΨL), stomatal conductance (g s), wood density, and Huber value (sapwood area:leaf area) of the 22 study species. We found significant differences in the water relations of these two species types. Leaf area specific hydraulic conductance of the soil/root/leaf pathway (G t) was greater for savanna species than forest species. The lower G t of forest trees resulted in significantly lower ΨL and g s in the late dry season relative to savanna trees. The differences in G t can be explained by differences in biomass allocation of savanna and forest trees. Savanna species had higher Huber values relative to forest species, conferring greater transport capacity on a leaf area basis. Forest trees have a lower capacity to maintain homeostasis in ΨL due to greater allocation to leaf area relative to savanna species. Despite significant differences in water relations, relationships between traits such as wood density and minimum ΨL were indistinguishable for the two species groups, indicating that forest and savanna share a common axis of water-use strategies involving multiple traits.}, number={2}, journal={OECOLOGIA}, author={Gotsch, Sybil G. and Geiger, Erika L. and Franco, Augusto C. and Goldstein, Guillermo and Meinzer, Frederick C. and Hoffmann, William A.}, year={2010}, month={Jun}, pages={291–301} }
 @article{huang_geiger_van leeuwen_marsh_2009, title={Discrimination of invaded and native species sites in a semi-desert grassland using MODIS multi-temporal data}, volume={30}, ISSN={["1366-5901"]}, DOI={10.1080/01431160802395243}, abstractNote={Over the past several decades, one of the most significant changes in semi‐desert grasslands of the southwestern US has been the invasion of South African grass Eragrostis lehmanniana. The objective of this study was to characterize the phenology of systems occupied by E. lehmanniana and/or native grasses using time‐series of field observations and the Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index (MODIS NDVI) and brightness (red and near‐infrared reflectance) data. Results demonstrated that it was possible to use NDVI and/or spectral reflectance data to discern the phenological differences across a gradient of E. lehmanniana infested grasslands due to variations in plant biodiversity, morphology and seasonal productivity. This work establishes the feasibility of integrating field and MODIS vegetation and spectral time‐series data to characterise landscapes dominated by different herbaceous species, which in turn provides opportunities to monitor E. lehmanniana in semi‐arid environments at a large spatial scale.}, number={4}, journal={INTERNATIONAL JOURNAL OF REMOTE SENSING}, author={Huang, C. and Geiger, E. L. and Van Leeuwen, W. J. D. and Marsh, S. E.}, year={2009}, pages={897–917} }
 @article{hoffmann_adasme_haridasan_carvalho_geiger_pereira_gotsch_franco_2009, title={Tree topkill, not mortality, governs the dynamics of savanna-forest boundaries under frequent fire in central Brazil}, volume={90}, ISSN={["1939-9170"]}, DOI={10.1890/08-0741.1}, abstractNote={Tropical savanna and forest are recognized to represent alternate stable states, primarily determined by feedbacks with fire. Vegetation–fire dynamics in each of these vegetation types are largely determined by the influence of the vegetation on fire behavior, as well as the effects of fire behavior on tree mortality, topkill (defined here as complete death of the aerial biomass, regardless of whether the plant recovers by resprouting), and rate of growth of resprouts. We studied the effect of fire on three savanna–forest boundaries in central Brazil. Fire intensity was greater in savanna than forest, as inferred by a twofold greater height of stem charring. Despite lower fire intensity, forest tree species exhibited higher rates of topkill, which was best explained by their thinner bark, relative to savanna species. Following topkill, there was no tendency for sprouts of savanna trees to grow faster than those of forest species, contrary to expectations, nor was whole‐plant mortality higher in forest than in savanna. This contrasts with observations of high rates of postburn mortality in many other tropical forests. The low tree mortality in these transitional forests suggests that the dynamic of these natural savanna–forest boundaries is fundamentally different from that of forest boundaries originating from deforestation in the humid tropics. The forests studied here appear to be much more resilient to occasional incursion of fire from the savanna, despite being unable to invade frequently burned savanna. The thin bark of forest species makes them particularly susceptible to the “fire trap,” whereby repeated topkill of small trees prevents recruitment into adult size classes. Rapid growth will be particularly important for forest species to escape the fire trap, so we predict that, where fire is frequent, forests should be restricted to high‐resource sites. Here, Mg2+ and Ca2+ concentrations had particularly strong effects on postburn growth rates, suggesting that these elements may most strongly limit the distribution of forest in these fire‐prone savannas.}, number={5}, journal={ECOLOGY}, author={Hoffmann, William A. and Adasme, Ryan and Haridasan, M. and Carvalho, Marina T. and Geiger, Erika L. and Pereira, Mireia A. B. and Gotsch, Sybil G. and Franco, Augusto C.}, year={2009}, month={May}, pages={1326–1337} }
 @article{huang_geiger_2008, title={Climate anomalies provide opportunities for large-scale mapping of non-native plant abundance in desert grasslands}, volume={14}, number={5}, journal={Diversity & Distributions}, author={Huang, C. Y. and Geiger, E. L.}, year={2008}, pages={875–884} }