【植物残留物-微生物系统中的化学计量变化】Nicolas Fanin Nathalie Fromin Bruno Buatois Stephan Hättenschwiler. An experimental test of the hypothesis of non-homeostatic consumer stoichiometry in a plant litter–microbe system. Ecology Letters
Abstract
Stoichiometric homeostasis of heterotrophs is a common but not always well-examined premise in ecological stoichiometry. We experimentally evaluated the relationship between substrate (plant litter) and consumer (microorganisms) stoichiometry for a tropical terrestrial decomposer system. Variation in microbial C : P and N : P ratios tracked that of the soluble litter fraction but not that of bulk leaf litter material. Microbial N and P were not isometrically related suggesting higher rates of P than N sequestration in microbial biomass. Shifts in microbial stoichiometry were related to changes in microbial community structure. Our results indicate that P in dissolved form is a major driver of terrestrial microbial stoichiometry similar to aquatic environments. The demonstrated relative plasticity in microbial C : P and N : P and the critical role of P have important implications for theoretical modelling and contribute to a process-based understanding of stoichiometric relationships and the flow of elements across trophic levels in decomposer systems.
【多树种林中跨土壤肥力梯度的竞争性相互作用】K. David Coates Erica B. Lilles Rasmus Astrup. Competitive interactions across a soil fertility gradient in a multispecies forest. Journal of Ecology
Abstract
- Whether plant competition grows stronger or weaker across a soil fertility gradient is an area of great debate in plant ecology. We examined the effects of competition and soil fertility and their interaction on growth rates of the four dominant tree species in the sub-boreal spruce forest of British Columbia.
- We tested separate soil nutrient and moisture indices and found much stronger support for models that included the nutrient index as a measure of soil fertility.
- Competition soil fertility and their interaction affected radial growth rates for all species.
- Each species supported a different alternate hypothesis for how competitive interactions changed with soil fertility and whether competition intensity was stronger or weaker overall as soil fertility increased depended on the context specifically species neighbourhood composition and type of competition (shading vs. crowding).
- The four species varied slightly in their growth response to soil fertility.
- Individual species had some large variations in the shapes of their negative relationships between shading crowding and tree growth with one species experiencing no net negative effects of crowding at low soil fertility.
- Good