Forest species composition in Florida is sensitive to changes in hydrology that accompany small shifts in elevation. In this study, we use dendrochronological techniques to determine how the growth of Pinus elliottii var. elliottii Engelm. (slash pine) and Pinus palustris Mill. (longleaf pine) along a hydrologic gradient from mesic flatwoods to xeric sandhills responds to fluctuations in climate (temperature, precipitation, river flow, and Palmer drought severity index). Interspecies and intraspecies comparisons of growth responses were made between a xeric P. palustris plot, a transition zone plot containing both species, and a mesic P. elliottii plot. Growth of P. elliottii individuals was negatively correlated with increased water availability on sites with a shallow water table (<1 m) but positively correlated on sites with a deeper water table. The basal area increment (BAI) of P. elliottii individuals on the drier site was 41% lower than the BAI of individuals on the wetter site. In contrast, the growth response of P. palustris, which only grows in the dryer sites, was similar along the hydrologic gradient, with growth being positively related to water availability and only a 16% lower BAI on the driest site.

The combined effects of fire history, climate, and landscape features (e.g., edges) on habitat specialists need greater focus in fire ecology studies, which usually only emphasize characteristics of the most recent fire. Florida scrub‐jays are an imperiled, territorial species that prefer medium (1.2–1.7 m) shrub heights, which are dynamic because of frequent fires. We measured short, medium, and tall habitat quality states annually within 10‐ha grid cells (that represented potential territories) because fires and vegetative recovery cause annual variation in habitat quality. We used multistate models and model selection to test competing hypotheses about how transition probabilities vary between states as functions of environmental covariates. Covariates included vegetative type, edges (e.g., roads and forests), precipitation, openings (gaps between shrubs), mechanical cutting, and fire characteristics. Fire characteristics not only included an annual presence/absence of fire covariate, but also fire history covariates: time since the previous fire, the longest fire‐free interval, and the number of repeated fires. Statistical models with support included many covariates for each transition probability, often including fire history, interactions, and nonlinear relationships. Tall territories resulted from 28 yr of fire suppression and habitat fragmentation that reduced the spread of fires across landscapes. Despite 35 yr of habitat restoration and prescribed fires, half the territories remained tall, suggesting a regime shift to a less desirable habitat condition. Edges reduced the effectiveness of fires in setting degraded scrub and flatwoods into earlier successional states, making mechanical cutting an important tool to compliment frequent prescribed fires.

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Society needs information about how vegetation communities in coastal regions will be impacted by hydrologic changes associated with climate change, particularly sea level rise. Due to anthropogenic influences which have significantly decreased natural coastal vegetation communities, it is important for us to understand how remaining natural communities will respond to sea level rise. The Cape Canaveral Barrier Island complex (CCBIC) on the east central coast of Florida is within one of the most biologically diverse estuarine systems in North America and has the largest number of threatened and endangered species on federal property in the contiguous United States. The high level of biodiversity is susceptible to sea level rise. Our objective was to model how vegetation communities along a gradient ranging from hydric to upland xeric on CCBIC will respond to three sea level rise scenarios (0.2 m, 0.4 m, and 1.2 m). We used a probabilistic model of the current relationship between elevation and vegetation community to determine the impact sea level rise would have on these communities. Our model correctly predicted the current proportions of vegetation communities on CCBIC based on elevation. Under all sea level rise scenarios the model predicted decreases in mesic and xeric communities, with the greatest losses occurring in the most xeric communities. Increases in total area of salt marsh were predicted with a 0.2 and 0.4 m rise in sea level. With a 1.2 m rise in sea level approximately half of CCBIC’s land area was predicted to transition to open water. On the remaining land, the proportions of most of the vegetation communities were predicted to remain similar to that of current proportions, but there was a decrease in proportion of the most xeric community (oak scrub) and an increase in the most hydric community (salt marsh). Our approach provides a first approximation of the impacts of sea level rise on terrestrial vegetation communities, including important xeric upland communities, as a foundation for management decisions and future modeling.

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Despite the severe impacts of the Deepwater Horizon oil spill, the foundation plant species Spartina alterniflora proved resilient to heavy oiling, providing an opportunity to identify mechanisms of response to the anthropogenic stress of crude oil exposure. We assessed plants from oil-affected and unaffected populations using a custom DNA microarray to identify genomewide transcription patterns and gene expression networks that respond to crude oil exposure. In addition, we used T-DNA insertion lines of the model grass Brachypodium distachyon to assess the contribution of four novel candidate genes to crude oil response. Responses in S. alterniflora to hydrocarbon exposure across the transcriptome as well as xenobiotic specific response pathways had little overlap with those previously identified in the model plant Arabidopsis thaliana. Among T-DNA insertion lines of B. distachyon, we found additional support for two candidate genes, one (ATTPS21) involved in volatile production, and the other (SUVH5) involved in epigenetic regulation of gene expression, that may be important in the response to crude oil. The architecture of crude oil response in S. alterniflora is unique from that of the model species A. thaliana, suggesting that xenobiotic response may be highly variable across plant species. In addition, further investigations of regulatory networks may benefit from more information about epigenetic response pathways.

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