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Abstract Climate change poses a growing threat to many ecosystems, including grasslands, which are a current priority for conservation due to their vulnerability to interacting threats from human activity.North American grasslands are expected to experience warmer temperatures and more frequent and severe droughts in the coming decades, with potential consequences for native biodiversity.We conducted an experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA, to investigate how warming and drought treatments affected grassland plant community structure over 6 years in plots planted with species mixtures.Warming consistently reduced plant species richness with its effects on Shannon diversity (which additionally considers species' relative abundances) and dominance varying across years. These warming‐by‐year interactions were likely driven by temporal variability in environmental conditions and species‐specific responses. Notably, legumes consistently showed positive responses to warming.Drought alone had minimal direct effects on species richness and diversity but reduced variability in diversity responses over time, suggesting greater stability of diversity under drought conditions.Synthesis. This study underscores the important role of warming in reducing species richness, altering diversity and reshaping functional group composition in grassland ecosystems. While temporal variability influenced the magnitude of warming effects on diversity, legumes' positive responses highlight the importance of functional group dynamics in potentially buffering against species loss. Long‐term experiments that allow consideration of interannual variability are essential for improving predictions of ecosystem responses and informing adaptive management strategies aimed at sustaining biodiversity and ecosystem functioning in grasslands.
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Home‐field advantage, N‐priming and precipitation independently govern litter decomposition in a plant diversity manipulation
Abstract Litter decomposition facilitates the recycling of often limiting resources, which may promote plant productivity responses to diversity, that is, overyielding. However, the direct relationship between decomposition,k, and overyielding remains underexplored in grassland diversity manipulations.We test whether local adaptation of microbes, that is, home‐field advantage (HFA), N‐priming from plant inputs or precipitation drive decomposition and whether decomposition generates overyielding. Within a grassland diversity‐manipulation, altering plant richness (1, 2, 3 and 6 species), composition (communities composed of plants from a single‐family or multiple‐families) and precipitation (50% and 150% ambient growing season precipitation), we conducted a litter decomposition experiment. In spring 2020, we deployed four replicate switchgrass,Panicum virgatum, litter bags (1.59 mm mesh opening), collecting them over 7 months to estimate litterk.Precipitation was a strong, independent driver of decomposition. Switchgrass decomposition accelerated with grass richness and decelerated as phylogenetic dissimilarity from switchgrass increased, suggesting decomposition is fastest at ‘home’. However, decomposition slowed with switchgrass density. In plots that contained switchgrass, we observed no relationship between decomposition and fungal saprotroph dissimilarity from switchgrass. However, in plots without switchgrass, decomposition slowed with increasing saprotroph dissimilarity from switchgrass. Combined these findings suggest that HFA is strongest when closely related neighbours, that is, heterospecific neighbours, are present in the community, rather than other individuals of the same species, that is, conspecifics. Legumes accelerated decomposition with more litter N remaining in those plots, suggesting that N‐inputs from planted legumes are priming decomposition of litter C. However, decomposition and overyielding were unrelated in legume communities. While in grass communities, overyielding and decomposition were positively related and the relationship was strongest in plots with low densities of switchgrass, that is, with heterospecific neighbours.Combined these findings suggest that plant species richness and community composition stimulate litter decomposition through multiple mechanisms, including N‐priming, but only HFA from local adaptation of microbes on closely related species correlates with overyielding, likely through resource recycling. Our results link diversity with ecosystem processes facilitating above‐ground productivity. Whether diversity loss will affect litter decomposition, productivity or both is contingent on resident plant traits and whether a locally adapted soil microbiome is maintained. Read the freePlain Language Summaryfor this article on the Journal blog.
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- PAR ID:
- 10489975
- Publisher / Repository:
- Functional Ecology
- Date Published:
- Journal Name:
- Functional Ecology
- ISSN:
- 0269-8463
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/1365-2435.14515
