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Uncertainty in ecosystem restoration can be mitigated by information on drivers of variability in restoration outcomes, especially through experimental study. In southeastern USA pine savannas, efforts to restore the perennial bunchgrass wiregrass (Aristida beyrichiana) often achieve variable outcomes in the first year. Although ecotypic differentiation and competition with other native vegetation are known to influence wiregrass seedling establishment and growth, to our knowledge, no studies have examined interactions between these drivers. We experimentally quantified individual and interactive effects of competition, seed source, and soil type on wiregrass density, size, and flowering culm production in the field. We sowed seeds from dry and wet sites reciprocally into dry and wet soils and weeded half of the plots. We found that competition removal resulted in significantly larger plants and a greater proportion of flowering plants with more culms on average, regardless of seed source or soil type. Seeds sourced from a wet site resulted in more plants per plot than seeds from a dry site, which might have been influenced by the greater number of filled seeds from the wet site. After seedlings become established, competition contributes to variation in growth and reproduction. Although competition removal could help start wiregrass populations, the necessity of mitigation depends on fire management needs. [ABSTRACT FROM AUTHOR]

Overstory trees serve multiple functions in grassy savannas. Past research has shown that understory species can vary along gradients of canopy cover and basal area in savannas. This variation is frequently associated with light availability but could also be related to other mechanisms, such as heterogeneity in soil and litter depth and fire intensity. Several savanna studies have found differences in understory plant functional groups within the local environment near trees versus away from them in canopy openings. Although small‐scale variation is known to be high in southeastern U.S. pine savannas, patterns in understory species diversity have not been examined at the scale of individual overstory pine trees in this system. We conducted an observational study of the relationship between understory plant communities and proximity to individual pine trees in xeric and mesic pine savannas in frequently burned sites (1–3 year intervals). We recorded the plant community composition in plots adjacent to tree boles (basal) or outside crown driplines (open). Within each environment, raw species richness was significantly greater in open locations, where light transmittance was greater. In contrast, rarified species richness did not differ. Multivariate analyses showed that community composition differed significantly between basal and open plots. One native, woody species in each environment, Serenoa repens (W. Bartram) Small in mesic and Diospyros virginiana L. in xeric, was more abundant in basal plots. In mesic environments, eight species had greater occurrence in open plots. In xeric environments, four understory forbs were more abundant in open plots. Our results support previous research indicating that individual pine trees are associated with significant variation in understory vegetation in pine savannas. [ABSTRACT FROM AUTHOR]

Subtropical calcareous wet grasslands (SCWG) are pyrogenic hyper-seasonal grasslands with exceptional vascular plant biodiversity and conservation value in south-central Florida with floristic affinities to southern Florida marl grasslands, and both are dominated by Muhlenbergia sericea. We sampled 62 sites (n = 124 samples), of which 62 were surface soil samples (upper 1–10 cm), and 62 were subsurface soils (above the spodic horizon) across the edaphic-hydrologic gradient of savanna-grassland landscape in south-central Florida. We sought to determine how soil chemistry (17 variables) and texture (7 categories) might correlate with floristic composition and distinguish SCWG from savanna-grassland community types in peninsular Florida. To test which soil PCA axes were associated with plant community types, we used correlations between NMDS plot scores and the scores of significant soil PCA axes. Surface and subsurface soil chemistry were significantly correlated with dimensions of variation in savanna-grassland plant community types. In SCWG, soil chemistry is segregated because of higher Ca, pH, and percentage base saturation in subsurface soils. Lower cation exchange capacity, surface and subsurface soil texture with greater fine sand particles, lower silt, and higher clay content differentiate SCWG. Our results highlight the edaphic-hydrologic distinctiveness of SCWG, which supports previous recognition based solely on floristic and species composition, where calciphilic habitat specialists coexist with plants otherwise characteristic of brackish marsh, acidic grassland, and xeric sands. [ABSTRACT FROM AUTHOR]

Premise: In frequently burned southeastern USA pine‐grassland communities, wiregrass (Aristida stricta and A. beyrichiana) are dominant bunchgrasses whose flowers are infected during flowering by a smut fungus (Langdonia walkerae). We hypothesized that because prescribed fire timing affects wiregrass flowering patterns, it could affect smut incidence (occurrence of smut on plants) and severity of infection in inflorescences and spikelets. Because soil order could influence plant susceptibility, we hypothesized that these patterns would differ between soil orders. We hypothesized differences between species as representative of geographic variation in this ecosystem. Methods: We surveyed the incidence and severity of L. walkerae in wiregrass populations (85 populations at 14 sites) that had been prescription burned at different times during the previous year. We used binomial regressions to test whether incidence and severity differed by burn day, soil order, or species, with site as a random effect. Results: Fires that occurred in the winter were associated with significantly lower incidence than fires later in the year (as the months progressed into summer). Plants growing on Spodosol soils were significantly less likely to be infected than those on other soils. More variation in incidence, however, was explained by site, suggesting that site‐specific characteristics were important. Smut severity in inflorescences and spikelets was greater overall in populations of A. stricta than in southern populations (A. beyrichiana). Conclusions: Our findings indicate that fire timing and soil order affect L. walkerae incidence in wiregrass plants, but neither appears to be associated with greater severity. Patterns of smut infection are related to site history and geographic variation. [ABSTRACT FROM AUTHOR]

Grass species are often included during restoration to reinstate feedbacks with fire. In biodiverse pine savannas of the southeastern United States, wiregrass (Aristida beyrichiana) is the preferred candidate for restoring low‐intensity fires through the understory. Less common but locally co‐dominant in dry pine savannas, pineywoods dropseed (Sporobolus junceus) is another bunchgrass candidate for restoration. If two bunchgrass species associate with different suites of plants in the understory, restoring both could support a twofold goal of restoring fire regimes and plant biodiversity. To guide restoration goals, we tested the hypothesis that in natural (i.e. not recently restored) dry pine savannas in North Florida where wiregrass and dropseed are co‐dominant, they are associated with different understory plant species richness, occurrence, and abundance under or adjacent to their canopies. Species richness of associated plants did not differ between bunchgrass species or with distance from bunchgrass (i.e. under vs. adjacent). Some associated plant species, however, were more likely to occur and had greater abundance with one or the other bunchgrass species irrespective of distance. Our results suggest that including more than one bunchgrass species in restoration plantings could increase dry pine savanna biodiversity while also reinstating plant‐fire feedbacks. [ABSTRACT FROM AUTHOR]

Keywords: fire ecology; prescribed fire; rainfall; seasonality; wildfire EN fire ecology prescribed fire rainfall seasonality wildfire e5 e6 2 01/23/21 20210215 NES 210215 Regional fire regimes, as well as their effects, are influenced by precipitation patterns, including amount and variability. Terando et al.'s (2020) objective was to address the utility of the CRA method for defining a "climatologically" or "physically meaningful" precipitation seasonality in the southeastern U.S. Although they use CRA amplitude to quantify seasonality, they do not suggest an objective threshold above which seasonality is meaningful. [Extracted from the article]

AbstractPrescribed fires are used to manage natural areas and mitigate potentially intense and catastrophic wildfires. Education and other outreach activities can increase the acceptance and adoption of prescribed fire use among private landowners. Land grant university-based Extension services are often a trusted source of information in communities on a variety of topics, but no published research has previously assessed Extension’s capacity for prescribed fire education and training. This study uses semi-structured interviews to explore the knowledge and experiences of 23 southeastern U.S. Extension professionals with prescribed fire outreach. Thematic analysis of the interviews guided by Ostrom’s social-ecological systems framework revealed that these Extension professionals face a variety of challenges stemming from their institutions, audiences, and own backgrounds that complicate prescribed fire outreach. These challenges can be overcome, allowing Extension professionals to conduct fire science outreach and play an active role in facilitating networks to build capacity through cooperation. [ABSTRACT FROM AUTHOR]