Distinct responses of niche and fitness differences to water availability underlie variable coexistence outcomes in semi-arid annual plant communities

Climate change is predicted to have profound consequences for multispecies coexistence, and thus, patterns of biological diversity. These consequences will be mediated by direct and indirect impacts of environmental change on species’ vital rates and interactions. While the impacts of environmental change on individual species has received much attention to date, the consequences for coexistence mediated by changes in the strength and direction of multispecies interactions are not as well understood. To investigate how coexistence dynamics may be sensitive to environmental change, we conducted a field experiment in a diverse semi-arid annual plant system. We imposed a water manipulation treatment in two sites that vary in aridity and associated rainfall. Focusing on four common annual plant species in these sites, we quantified the fecundity (seed production) of individuals in response to a gradient of intra- and interspecific competitor densities and aridity. We then used these fecundities to parameterize an annual plant population model and examine the influence of aridity and species identity on resultant coexistence dynamics (as a function of stabilizing niche differences and fitness inequalities). While the responses of some vital rates and competitive impacts to watering varied somewhat predictably across sites, coexistence metrics encapsulating changes in these vital rates and interaction strengths did not. Fitness inequalities among our focal species were driven largely by differences in sensitivity to competition, which were almost always much greater than the magnitude of stabilizing niche differences. These findings were surprising given observational evidence suggesting that these species do coexist at local scales in these natural communities. Synthesis. Our study is one of the first to explicitly consider the influence of environmental variation on the individual components of coexistence outcomes. We show that environmental change has the ability to influence coexistence not only through direct pathways (i.e., vital rates), but also indirect pathways (i.e., species interactions). Despite the consistency of many of the responses of these individual components to environmental variation, their combined influence on predictions of both current and future coexistence remains unclear

Asteraceae invaders have limited impacts on the pollination of common native annual species in SW Western Australia’s open woodland wildflower communities

The York gum-jam woodlands of southwest Western Australia support diverse annual wildflower communities despite extensive habitat fragmentation, remnant isolation and the invasion of many exotic annual plant species. Few studies have explored the pollinator-plant relationships maintaining these persistently species-rich 'novel' communities. We examine the pollination ecology of five native species common to York gum-jam woodland annual communities to determine whether native pollinators may be mediating impacts of exotic annual plants on native wildflower species. We determined the pollination requirements of native focal species and the diversity and frequency of pollinator visitation to these focal plant species across invasion gradients. We also recorded the pollinator community of a dominant exotic herb in this system: Arctotheca calendula (cape weed). Only two of the five native species examined had significant seed set benefits attributable to insect pollination. One native plant species, Podotheca gnaphalioides, had pollinator assemblages that overlapped significantly with exotic A. calendula, with some reduction in pollinator visitation evident. One species, Waitzia acuminata, was found to benefit from insect pollination only in the larger of two surveyed remnants, which may reflect emerging reproductive polymorphism among geographically isolated populations. We highlight two mechanisms in this system that may buffer pollinator-mediated impacts of exotic species on native species: autonomous seed production, which may be increasingly prevalent in isolated populations, and segregation of pollinator resources among species. Our findings illustrate the ways that pollinator-mediated interactions can affect seed set within plant communities persisting in highly fragmented and invaded agricultural landscapes

Potential mechanisms of coexistence in closely related forbs

The stable coexistence of very similar species has perplexed ecologists for decades and has been central to the development of coexistence theory. According to modern coexistence theory, species can coexist stably (i.e. persist indefinitely with no long-term density trends) as long as species' niche differences exceed competitive ability differences, even if these differences are very small. Recent studies have directly quantified niche and competitive ability differences in experimental communities at small spatial scales, but provide limited information about stable coexistence across spatial scales in heterogeneous natural communities. In this study, we use experimental and observational approaches to explore evidence for niche and competitive ability differences between two closely related, ecologically similar and widely coexisting annual forbs: Trachymene cyanopetala and T. ornata. We experimentally tested for stabilizing niche differences and competitive ability differences between these species by manipulating species' frequencies, under both well-watered and water-stressed conditions. We considered these experimental results in light of extensive field observations to explore evidence of niche segregation at a range of spatial scales. We found little evidence of intra-specific stabilization or competitive ability differences in laboratory experiments while observational studies suggested niche segregation across pollinator assemblages and small-scale microclimate heterogeneity. Though we did not quantify long-term stabilization of coexisting populations of these species, results are consistent with expectations for stable coexistence of similar species via a spatial storage effect allowing niche differences to overcome even small (to absent) competitive ability differences

Staples_et_al_Oikos_data

There are five excel sheets in this file, containing all data used for the main analyses in Staples et al. 2016 10.1111/oik.03180. Meta data for each data sheet is included in the associated README.txt fil

Data and R Code, Wainwright_JECOL_2018

Data and R code for maximum likelihood model fitting of annual plant population model for coexistence calculations. <div><br></div><div>Accompaniment to:<div>Wainwright CE, HilleRisLambers J, Lai HR, Loy X, Mayfield MM. Distinct responses of niche and fitness differences to water availability underlie variable coexistence outcomes in semi-arid annual plant communities. <i>Journal of Ecology.</i></div><div><br></div></div

Aridity drives coordinated trait shifts but not decreased trait variance across the geographic range of eight Australian trees

Large intraspecific functional trait variation strongly impacts many aspects of communities and ecosystems, and is the medium upon which evolution works. Yet intraspecific trait variation is inconsistent and hard to predict across traits, species and locations. We measured within-species variation in leaf mass per area (LMA), leaf dry matter content (LDMC), branch wood density (WD), and allocation to stem area vs leaf area in branches (branch Huber value (HV)) across the aridity range of seven Australian eucalypts and a co-occurringAcaciaspecies to explore how traits and their variances change with aridity. Within species, we found consistent increases in LMA, LDMC and WD and HV with increasing aridity, resulting in consistent trait coordination across leaves and branches. However, this coordination only emerged across sites with large climate differences. Unlike trait means, patterns of trait variance with aridity were mixed across populations and species. Only LDMC showed constrained trait variation in more xeric species and drier populations that could indicate limits to plasticity or heritable trait variation. Our results highlight that climate can drive consistent within-species trait patterns, but that patterns might often be obscured by the complex nature of morphological traits, sampling incomplete species ranges or sampling confounded stress gradients

Links between community ecology theory and ecological restoration are on the rise

1. Community ecology is frequently invoked as complementary to and useful for guiding ecological restoration. While the conceptual literature is devoted to this unification, first-hand accounts from practitioners and ecologists suggest that integration may be weak in practice. To date, there have been no analyses of how extensively community ecology theory appears in the empirical restoration literature

Wainwright_JAPPL_2017.csv

Studies assessed in a literature review of ecological restoration experiments and their incorporation of various concepts, hypotheses, models and conceptually-derived tools in community ecology.<br><br>Studies are journal articles from the peer-reviewed literature spanning 1995 to 2015. <br><br>Fields include: journal, year of publication, authors, title of study, study location (country), lead author location of primary institution (country), study location (region), lead author location of primary institution (region), institution, type, focal organism type, and focal ecosystem type. <br

Conserving alpha and beta diversity in wood-production landscapes

International demand for wood and other forest products continues to grow rapidly, and uncertainties remain about how animal communities will respond to intensifying resource extraction associated with woody bioenergy production. We examined changes in alpha and beta diversity of bats, bees, birds, and reptiles across wood production landscapes in the southeastern United States, a biodiversity hotspot that is one of the principal sources of woody biomass globally. We sampled across a spatial gradient of paired forest land-uses (representing pre and postharvest) that allowed us to evaluate biological community changes resulting from several types of biomass harvest. Short-rotation practices and residue removal following clearcuts were associated with reduced alpha diversity (−14.1 and −13.9 species, respectively) and lower beta diversity (i.e., Jaccard dissimilarity) between land-use pairs (0.46 and 0.50, respectively), whereas midrotation thinning increased alpha (+3.5 species) and beta diversity (0.59). Over the course of a stand rotation in a single location, biomass harvesting generally led to less biodiversity. Cross-taxa responses to resource extraction were poorly predicted by alpha diversity: correlations in responses between taxonomic groups were highly variable (−0.2 to 0.4) with large uncertainties. In contrast, beta diversity patterns were highly consistent and predictable across taxa, where correlations in responses between taxonomic groups were all positive (0.05–0.4) with more narrow uncertainties. Beta diversity may, therefore, be a more reliable and information-rich indicator than alpha diversity in understanding animal community response to landscape change. Patterns in beta diversity were primarily driven by turnover instead of species loss or gain, indicating that wood extraction generates habitats that support different biological communities.Fil: Gavin, Jones M.. University of Florida. Department of Wildlife Ecology and Conservation; Estados Unidos. USDA Forest Service. Rocky Mountain Research Station; Estados UnidosFil: Brosi, Berry. University of Washington; Estados Unidos. University of Emory; Estados UnidosFil: Evans, Jason. Stetson University. Department of Environmental Science and Studies; Estados UnidosFil: Gottlieb, Isabel G. W.. University of Florida; Estados UnidosFil: Loy, Xingwen. University of Emory; Estados Unidos. Atlanta Botanical Garden. Conservation & Research Department; Estados UnidosFil: Núñez Regueiro, Mauricio Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina. University of Florida; Estados UnidosFil: Ober, Holly K.. University of Florida. Department of Wildlife Ecology and Conservation; Estados UnidosFil: Pienaar, Elizabeth. University of Georgia; Estados Unidos. University of Pretoria. Mammal Research Institute; Estados UnidosFil: Pillay, Rajeev. University of Florida. Department of Wildlife Ecology and Conservation; Estados UnidosFil: Pisarello, Kathryn. University of Florida. Department of Wildlife Ecology and Conservation; Estados UnidosFil: Smith, Lora L.. Jones Center at Ichauway; Estados UnidosFil: Fletcher, Robert J.. University of Florida. Department of Wildlife Ecology and Conservation; Estados Unido

Conserving alpha and beta diversity in wood-production landscapes

International demand for wood and other forest products continues to grow rapidly, and uncertainties remain about how animal communities will respond to intensifying resource extraction associated with woody bioenergy production. We examined changes in alpha and beta diversity of bats, bees, birds, and reptiles across wood production landscapes in the southeastern United States, a biodiversity hotspot that is one of the principal sources of woody biomass globally. We sampled across a spatial gradient of paired forest land-uses (representing pre and postharvest) that allowed us to evaluate biological community changes resulting from several types of biomass harvest. Short-rotation practices and residue removal following clearcuts were associated with reduced alpha diversity (-14.1 and -13.9 species, respectively) and lower beta diversity (i.e., Jaccard dissimilarity) between land-use pairs (0.46 and 0.50, respectively), whereas midrotation thinning increased alpha (+3.5 species) and beta diversity (0.59). Over the course of a stand rotation in a single location, biomass harvesting generally led to less biodiversity. Cross-taxa responses to resource extraction were poorly predicted by alpha diversity: correlations in responses between taxonomic groups were highly variable (-0.2 to 0.4) with large uncertainties. In contrast, beta diversity patterns were highly consistent and predictable across taxa, where correlations in responses between taxonomic groups were all positive (0.05-0.4) with more narrow uncertainties. Beta diversity may, therefore, be a more reliable and information-rich indicator than alpha diversity in understanding animal community response to landscape change. Patterns in beta diversity were primarily driven by turnover instead of species loss or gain, indicating that wood extraction generates habitats that support different biological communities.SUPPORTING INFORMATION : APPENDIX S1. Distribution of the six land-use types across three ownerships (nonindustrial private, industrial timber, and local/state/federal). APPENDIX S2. Occupancy and detection covariate structures for multispecies occupancy models. APPENDIX S3. Alpha-diversity across the six sampled land uses. APPENDIX S4. Beta-diversity components (total Jaccard dissimilarity, Jaccard turnover, and Jaccard nestedness) for pairwise bioenergy contrasts. APPENDIX S5. Average beta-diversity and beta-diversity components for pairwise land-use comparisons across bats, bees, birds, and reptiles APPENDIX S6. Beta-diversity components (total Jaccard dissimilarity, Jaccard turnover, and Jaccard nestedness) within each of the six land use typesUS Department of Agriculture - NIFA.https://wileyonlinelibrary.com/journal/cobi2022-12-02hj2022Mammal Research Institut