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Abstract Seeds provide the basis of genetic diversity in perennial grassland communities and their traits may influence ecosystem resistance to extreme drought. However, we know little about how drought effects the community functional composition of seed traits and the corresponding implications for ecosystem resistance to drought.We experimentally removed 66% of growing season precipitation for 4 years across five arid and semi‐arid grasslands in northern China and assessed how this multi‐year drought impacted community‐weighted means (CWMs) of seed traits, seed trait functional diversity and above‐ground net primary productivity (ANPP).Experimental drought had limited effects on CWM traits and the few effects that did occur varied by site and year. For three separate sites, and in different years, drought reduced seed length and phosphorus content but increased both seed and seed‐coat thickness. Additionally, drought led to increased seed functional evenness, divergence, dispersion and richness, but only in some sites, and mostly in later years following cumulative effects of water limitation. However, we observed a strong negative relationship between drought‐induced reductions in ANPP and CWMs of seed‐coat thickness, indicating that a high abundance of dominant species with thick seeds may increase ecosystem resistance to drought. Seed trait functional diversity was not significantly predictive of ANPP, providing little evidence for a diversity effect.Our results suggest that monitoring community composition with a focus on seed traits may provide a valuable indicator of ecosystem resistance to future droughts despite inconsistent responses of seed trait composition overall. This highlights the importance of developing a comprehensive seed and reproductive traits database for arid and semi‐arid grassland biomes. Read the freePlain Language Summaryfor this article on the Journal blog.
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Sequential disturbances alter the outcome of inter‐genotypic interactions in a clonal plant
Abstract Multiple disturbances can have mixed effects on biodiversity. Whether the interaction of sequential disturbances drives local extinctions or promotes diversity depends on the severity of biomass reductions relative to any stabilizing and/or equalizing effects generated by the disturbance regimes.Through a manipulative mesocosm experiment, we examined how warming events in the fall and simulated grazing disturbance (i.e. clipping) in the winter affected the density, biomass and genotypic diversity of assemblages of the clonal seagrassZostera marina.We show that the interaction of the two disturbance types reduced density and biomass to a greater degree than warming or clipping alone.The genotype with the highest biomass in the assemblage shifted under the different experimental regimes such that the traits of winners were distinct in the different treatments. The favouring of different traits by different disturbances led to reduced evenness when a single disturbance was applied, and enhanced evenness under multiple disturbances.We conclude that sequential disturbances can alter the outcome of inter‐genotypic interactions and maintain genotypic diversity in clonal populations. Our study expands the context in which disturbance can influence intraspecific diversity by showing that fluctuating selection may result from the sequential application of different disturbance types and not simply seasonal changes in a single agent. A freePlain Language Summarycan be found within the Supporting Information of this article.
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- Award ID(s):
- 1829976
- PAR ID:
- 10454651
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Functional Ecology
- Volume:
- 35
- Issue:
- 1
- ISSN:
- 0269-8463
- Page Range / eLocation ID:
- p. 127-138
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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