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1. The hidden legacy of megafaunal extinction: Loss of functional diversity and resilience over the Late Quaternary at Hall’s Cave

   https://doi.org/10.1111/geb.13428  

   Hedberg, Carson P. ; Lyons, S. Kathleen ; Smith, Felisa A. ; Schrodt, ed., Franziska ( November 2021 , Global Ecology and Biogeography)

   Functional traits mediate the interactions of species among themselves and with their environment, providing a link between diversity and ecosystem function. Crucially, the loss of biodiversity can jeopardize the functionality of ecosystems. Much focus is on predicting the impacts of current and future species loss; however, modern ecosystems have undergone biodiversity decline throughout the Late Quaternary, starting with the Pleistocene megafaunal extinctions. Thus, the fossil record offers the opportunity to investigate the long‐term legacy of biodiversity erosion and how this is affecting modern ecosystems in a cumulative manner. We aimed to investigate changes in functional diversity and redundancy of a local mammal community at Hall’s Cave, a site with a continuous record from 21,000 years ago to the present. Additionally, we included several common introduced species in the modern community to test whether they restore some lost ecological function.

   Central Texas.

   Late Pleistocene to Present.

   Mammals.

   We used eight functional traits (mass, diet, arboreality, cursoriality, soil disturbance, group size, activity period and migration habit), which, collectively, describe the ecological role of a species and its influence on ecosystem processes, to construct a multidimensional functional space. The functional richness, range and distribution of the Hall’s Cave community and the degree of functional redundancy were characterized statistically over time.

   We found that declines in functional diversity were greater than expected given the decrease in species richness, implying that lost taxa contributed higher than average distinct ecological function. Functional distances between the remaining species increased through time, leading to reduced functional redundancy in younger communities. However, recently introduced taxa increased functional diversity to levels similar to those in the Holocene and partly restored the functional space occupied by Late Pleistocene fauna.

   Our local‐scale analysis demonstrates how prolonged biodiversity erosion not only leads to functionally depauperate communities, but, crucially, lowers ecological resilience to future disturbance.

    

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2. Trait-based filtering mediates the effects of realistic biodiversity losses on ecosystem functioning

   https://doi.org/10.1073/pnas.2022757118  

   Wolf, Amelia A. ; Funk, Jennifer L. ; Selmants, Paul C. ; Morozumi, Connor N. ; Hernández, Daniel L. ; Pasari, Jae R. ; Zavaleta, Erika S. ( June 2021 , Proceedings of the National Academy of Sciences)

   Biodiversity losses are a major driver of global changes in ecosystem functioning. While most studies of the relationship between biodiversity and ecosystem functioning have examined randomized species losses, trait-based filtering associated with species-specific vulnerability to drivers of diversity loss can strongly influence how ecosystem functioning responds to declining biodiversity. Moreover, the responses of ecosystem functioning to diversity loss may be mediated by environmental variability interacting with the suite of traits remaining in depauperate communities. We do not yet understand how communities resulting from realistic diversity losses (filtered by response traits) influence ecosystem functioning (via effect traits of the remaining community), especially under variable environmental conditions. Here, we directly test how realistic and randomized plant diversity losses influence productivity and invasion resistance across multiple years in a California grassland. Compared with communities based on randomized diversity losses, communities resulting from realistic (drought-driven) species losses had higher invasion resistance under climatic conditions that matched the trait-based filtering they experienced. However, productivity declined more with realistic than with randomized species losses across all years, regardless of climatic conditions. Functional response traits aligned with effect traits for productivity but not for invasion resistance. Our findings illustrate that the effects of biodiversity losses depend not only on the identities of lost species but also on how the traits of remaining species interact with varying environmental conditions. Understanding the consequences of biodiversity change requires studies that evaluate trait-mediated effects of species losses and incorporate the increasingly variable climatic conditions that future communities are expected to experience.

    

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3. Geography of artiodactyl locomotor morphology as an environmental predictor

   https://doi.org/10.1111/ddi.13371  

   Short, Rachel A. ; Lawing, A. Michelle ; Thomassen, ed., Henri ( July 2021 , Diversity and Distributions)

   We investigate locomotor function in artiodactyls, represented by calcaneal gear ratio, as it relates to multiple environments. Using an ecometric approach, we develop a trait–environment model to investigate ecosystem‐level changes through time and to reconstruct past environments. We apply the trait–environment model to a case study of six sites in Kenya to evaluate changes over the past 100 years.

   Global.

   Locomotor morphology was represented by calcaneal gear ratios measured as the overall length of a calcaneum divided by length of its in‐lever, that is calcaneal tuber. We collected calcaneal gear ratio measurements from skeletal specimens of 157 artiodactyl species in museum collections and used species’ spatial distributions to determine the composition of 47,420 communities globally. For 21,827 communities with three or more species of artiodactyls, we used maximum likelihood to model ecometric relationships between community‐level locomotor morphology and five environmental variables, including mean annual temperature, annual precipitation, elevation, vegetation cover and ecoregion province.

   Community mean gear ratios range from 1.43 to 1.56 (µ = 1.50). Mean gear ratios are highest in the tropical regions and lowest in the mid‐latitudes. Variance in mean calcaneal gear ratio is related to ecoregion division (68.6%), vegetation cover (63.5%) and precipitation (60.7%). In a case study of Kenyan sites, we demonstrate habitat homogenization patterns that match mammal community turnover patterns.

   With this ecometric framework, fossils of artiodactyl post‐crania can be used to assist in interpreting past ecoregion, vegetation cover and precipitation for a more comprehensive understanding of palaeoenvironment. These relationships between functional traits and environment will enable better models of biotic responses for conservation of functional diversity under changing environments.

    

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4. Foredune‐forming grass and plant diversity show contrasting responses along the southeastern United States coast after hurricane disturbance

   https://doi.org/10.1111/jvs.13230  

   De Battisti, Davide ; Angelini, Christine ; Joyce, Matthew ; Crotty, Sinead ; Fairchild, Tom P. ; Fischman, Hallie S. ; Griffin, John N. ( January 2024 , Journal of Vegetation Science)

   Latitudinal gradients in plant communities are well studied, yet how these fundamental ecological patterns influence ecosystem recovery after extreme weather events remains largely unknown. In coastal foredunes, we investigated how the cover of a key dune‐building grass (Uniola paniculata), vegetation diversity and vegetation cover vary along a short latitudinal gradient during recovery from hurricane disturbance.

   Southeastern USA.

   We surveyed 24 sites, from central Florida to north Georgia (>400 km), four times over 18 months. General linear mixed‐effect models were used to unravel patterns of vegetation responses across latitude.

   Vegetation properties showed countervailing patterns across the latitudinal gradient. While vegetation richness, functional diversity and total cover generally declined,Uniolacover increased with increasing latitude. Further, the latitude–richness relationship strengthened while the latitude–functional diversity relationship was invariant with increasing time since the hurricane disturbance. Meanwhile, the latitude–Uniolaassociation was seasonally dependent and strongest in the summer. Latitude also influenced diversity–cover relationships: vegetation cover was positively related to species richness at lower latitudes, while it was positively associated with functional diversity only at northern sites. We found no relationship between species richness or functional diversity and increases in cover between time steps; however, recruitment of new species and functional groups was associated with increases in vegetation cover between time steps at northern sites.

   Our study highlights the temporal dynamism and contrasting patterns along latitudinal gradients exhibited by key engineering species and overall plant diversity in foredunes — a crucial line of coastal protection — exposed to hurricane disturbances. These results suggest a need for greater integration of latitudinal and diversity effects into our understanding of coastal dune resilience. They also highlight the potential benefits of enhancing dune plant biodiversity, particularly in areas where the dune‐building grasses that are classically employed in restoration (e.g.,Uniola) are unfavoured, to accelerate the re‐establishment of well‐vegetated dunes.

    

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5. Trait-Based Investigation Reveals Patterns of Community Response to Nutrient Enrichment in Coastal Mesic Grassland

   https://doi.org/10.3390/d13010019  

   Brown, Joseph K. ; Zinnert, Julie C. ( January 2021 , Diversity)

   null (Ed.)

   Despite recent advances, we still do not understand how chronic nutrient enrichment impacts coastal plant community structure and function. We aimed to clarify such impacts by testing for differences in ecosystem productivity and multiple community metrics in response to fertilization. We established plots in 2015 consisting of control (C), nitrogen (N), phosphorus (P), and nitrogen + phosphorus (NP) treatments in a mid-Atlantic coastal grassland. In 2017 we collected aboveground biomass, functional traits, and species abundance for each plot. Our findings indicate a synergistic co-limitation, such that NP plots were more productive than all other treatments. A combination of traits responsible for competition and nutrient uptake (i.e., height and δ15N) caused trait-based divergence of N and NP plots from C and P plots. Functional trait-based composition patterns differed from species composition and lifeform abundance patterns, highlighting complexities of community response to nutrient enrichment. While trait-based functional alpha-diversity did not differ among nutrient treatments, it was positively correlated with biomass production, suggesting nutrients may impact functional alpha-diversity indirectly through increased productivity. Increased functional alpha-diversity could be a mechanism of co-existence emerging as productivity increases. These results have important implications for understanding how plant communities in low-productivity coastal systems are altered by fertilization. 

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