Sally E. Koerner's research while affiliated with University of North Carolina at Greensboro and other places

Publications (17)

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We sought to understand the role that water availability (expressed as an aridity index) plays in determining regional and global patterns of richness and evenness, and in turn how these water availability-diversity relationships may result in different richness-evenness relationships at regional and global scales. We examined relationships between...
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Restoration of ecosystems is complex, with multiple targets that can work in concert or conflict with each other, such as biodiversity, species dominance, and biomass. When properly managed, longleaf pine (LLP) savannas are among the most biologically diverse habitats in the world. However, anthropogenic influences, such as fire suppression, have d...
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The longleaf pine (LLP) savanna ecosystem once covered ~ 92 million acres of the Southeast USA, but due to anthropogenic activities such as logging and fire suppression, only 3% of its once widespread historic range remains. While many restoration efforts are underway to conserve this biodiverse ecosystem, restoration must be done in the context of...
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Plants are subject to tradeoffs among growth strategies such that adaptations for optimal growth in one condition can preclude optimal growth in another. Thus, we predicted that a plant species that responds positively to one global change treatment would be less likely than average to respond positively to another treatment, particularly for pairs...
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Global change is impacting plant community composition, but the mechanisms underlying these changes are unclear. Using a dataset of 58 global change experiments, we tested the five fundamental mechanisms of community change: changes in evenness and richness, reordering, species gains and losses. We found 71% of communities were impacted by global c...
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Precipitation is a primary determinant of plant community structure in drylands. However, the empirical evidence and predictions are lacking for how plant functional diversity in desert and steppe communities respond to altered precipitation regimes. We examined how precipitation changes along the natural and experimental gradients affect different...
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Understanding how global change drivers (GCDs) affect aboveground net primary production (ANPP) through time is essential to predicting the reliability and maintenance of ecosystem function and services in the future. While GCDs, such as drought, warming and elevated nutrients, are known to affect mean ANPP, less is known about how they affect inte...
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Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42...
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Climatic extremes, such as severe drought, are expected to increase in frequency and magnitude with climate change. Thus, identifying mechanisms of resilience is critical to predicting the vulnerability of ecosystems. An exceptional drought (<1st percentile) impacted much of Southern Africa during the 2015 and 2016 growing seasons, including the si...
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Random species loss has been shown experimentally to reduce ecosystem function, sometimes more than other anthropogenic environmental changes. Yet, controversy surrounds the importance of this finding for natural systems where species loss is non‐random. We compiled data from 16 multi‐year experiments located at a single native tallgrass prairie si...
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Univariate and multivariate methods are commonly used to explore the spatial and temporal dynamics of ecological communities, but each has limitations, including oversimplification or abstraction of communities. Rank abundance curves (RACs) potentially integrate these existing methodologies by detailing species‐level community changes. Here, we had...
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Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of...
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Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet,...
Article
Full-text available
The responses of species to environmental changes will determine future community composition and ecosystem function. Many syntheses of global change experiments examine the magnitude of treatment effect sizes, but we lack an understanding of how plant responses to treatments compare to ongoing changes in the unmanipulated (ambient or background) s...
Article
Herbivores alter plant biodiversity (species richness) in many of the world's ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet,...

Citations

... Several studies have been conducted on exotic species invasion (Fig. 2). Climate substantially impacts plant and soil microbial diversity in terrestrial ecosystems (Ren et al., 2018;Korell et al., 2021;Zuo et al., 2021). In this meta-analysis, the sample distribution was relatively concentrated and introduced uncertainties in the meta-analysis. ...
... Our work suggests that this approach runs the risk of generating incorrect predictions, as density-dependent processes can yield ecological dynamics that vastly differ from direct environmental responses. Rather integrating community-level responses to multiple global change drivers through density-dependent and -independent mechanisms is critically needed for the maintenance of biodiversity (Avolio et al., 2021). ...
... Sensitivity analyses of previous simulation studies using the GRASSMIND model already detected a strong influence of parameters regarding plant geometry, photosynthesis and demography (Taubert et al. 2020a, Hetzer et al. 2021, Schmid et al. 2021), but also with high (non-linear) interactions to other model parameters. Thus, field studies that explicitly measure plant mortality rates or plant life spans, and plant densities (Lauenroth and Adler 2008, Hovenden et al. 2017, Wilcox et al. 2020 should be expanded in future observations to support a robust estimation of such model parameters. Nevertheless, plant mortality can have multiple reasons (e.g. ...
... Accordingly, human-driven increases in nutrient availability, a common disturbance of grasslands (Stevens et al., 2004), can strongly impact biomass production and its associated ecosystem services (Song et al., 2019;. Over time, chronic nutrient enrichment may impact different aspects of grassland biomass, including mean annual production (Fay et al., 2015;Seabloom et al., 2021), its standard deviation (henceforth 'interannual variability'; Avolio et al., 2020;Koerner et al., 2016), and its temporal stability (here, 'invariability' calculated as S = mean/standard deviation; Tilman, 1999;Tilman et al., 2006). While previous work has shown that multiple nutrient inputs can exert interactive effects on mean biomass production (Elser et al., 2007;Fay et al., 2015;Harpole et al., 2011), to date, it is not known if different single-or multiple-nutrient inputs exert independent or interactive effects on its interannual variability or overall stability. ...
... These include: (a) asynchronous dynamics, also known as compensatory dynamics, where declines in one species are compensated for by a rise in another, (b) stable dominant species, where aggregate stability depends on a few dominant species with high population stability, or (c) species richness driving portfolio effects, in which the community property is distributed among multiple species in a diverse community (especially when asynchronous). A growing body of work has highlighted that biotic stability mechanisms depend on the environmental context, with most studies exploring this in relation to bottom-up resource dynamics (Grman et al., 2010;Hallett et al., 2014;Xu et al., 2015;Hautier et al., 2020). Biotic stability mechanisms can shift along environmental gradients (Hallett et al., 2014), and resource variability can also cause shifts in mechanisms over time in the same system. ...
... Previous studies have demonstrated that regional spatial models of the ANPP-precipitation relationship for multiple locations have steeper slopes and higher regression coefficients than long-term temporal models at single locations (Estiarte et al., 2016;Lauenroth and Sala, 1992;O'Connor et al., 2001). The differences between the spatial and temporal controls of precipitation over ANPP arise primarily from the legacy effect of precipitation from previous years on current-year primary production (Reichmann and Sala, 2014;Reichmann et al., 2013;Sala et al., 2012), except for the well-documented ecosystem resilience (Hoover et al., 2014;Isbell et al., 2015;Wilcox et al., 2020). However, it remains unclear how multiple wet and dry years and attributes of plant community and soil affect the magnitude and directions of the legacy effect at broad scales, which is crucial to understanding the impacts of global climate change on functioning and services of grassland ecosystems. ...
... The last sublayer (presentation layer three) is related to ecosystems and covers not only biological features but also abiotic environments. Due to the strong effects of environmental factors such as temperature and geology on EFs [67][68][69], presentation layer three reflects abiotic factors in most cases. ...
... In this study we focus on using plant community structure (evenness, richness, and diversity) and reorganization to explain altered community composition. We used visualization of rank abundance curves (RACs) to explore whether systematic plant community re-organization contributes to community differences [52]. We hypothesize that 1) both aboveground and belowground graminoid and forb productivity will increase with N and NP treatments, 2) that N and NP additions will cause differences in community structure metrics (species diversity, richness, and evenness), and 3) compared to control plots (serving as a reference of a natural community), N and NP, enrichment will cause differences in community composition. ...
... In addition, while the aboveground biomass of herbaceous perennial plants often dies back over winter, root system responses (e.g. to drought-Ludlow and Muchow 1990; Wasaya et al. 2018 or to nutrient addition -Hodge 2004) can continue to develop over multiple years. A recent meta-analysis found that while in the short-term (< 10 years) plant communities appeared resistant to experimental manipulation of global change drivers, over the longer term there was increasing community divergence in treatment plots relative to in control plots (Komatsu et al. 2019). These results suggest that changes in species composition are important for driving further changes in plant productivity responses over the longer term, beyond any observed in the initial years of field experiments. ...
... Two recent meta-analyses provide limited support for model predictions that the plant diversity response to herbivore exclusion depends on resource availability (proxied by precipitation or aridity and plant biomass) 30,31 or evolutionary history of grazing 31 . However, these studies did not examine plant provenance which is needed to explore the evolutionary history of the whole plant community. ...