Recent advances in ecological stoichiometry: insights for population and community ecology

Abstract

T. 2005. Recent advances in ecological stoichiometry: insights for population and community ecology. Á/ Oikos 109: 29 Á/39.Conventional theories of population and community dynamics are based on a single currency such as number of individuals, biomass, carbon or energy. However, organisms are constructed of multiple elements and often require them (in particular carbon, phosphorus and nitrogen) in different ratios than provided by their resources; this mismatch may constrain the net transfer of energy and elements through trophic levels. Ecological stoichiometry, the study of the balance of elements in ecological processes, offers a framework for exploring ecological effects of such constraints. We review recent theoretical and empirical studies that have considered how stoichiometry may affect population and community dynamics. These studies show that stoichiometric constraints can affect several properties of populations (e.g. stability, oscillations, consumer extinction) and communities (e.g. coexistence of competitors, competitive interactions between different guilds). We highlight gaps in general knowledge and focus on areas of population and community ecology where incorporation of stoichiometric constraints may be particularly fruitful, such as studies of demographic bottlenecks, spatial processes, and multi-species interactions. Finally, we suggest promising directions for new research by recommending potential study systems (terrestrial insects, detritivory-based webs, soil communities) to improve our understanding of populations and communities. Our conclusion is that a better integration of stoichiometric principles and other theoretical approaches in ecology may allow for a richer understanding of both population and community structure and dynamics.S. J. Moe, Norwegian Inst. for Water Research, NO-0411 Oslo, Norway (jannicke. moe@niva.no) and

Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe

“…In fact, nitrogen deposition could promote plant diversity, because rare species are favoured under phosphorus-limited conditions 29 . The relationship between N:P stoichiometry and species diversity 30 is, moreover, not necessarily linear. For instance, Sasaki et al 25 have shown unimodal relationships between N:P stoichiometry and species richness in terrestrial ecosystems that reach a maximum at B20 biomass N:P ratio, that is, at a much lower ratio than current deposition ratios 4 .…”

“…For instance, Sasaki et al 25 have shown unimodal relationships between N:P stoichiometry and species richness in terrestrial ecosystems that reach a maximum at B20 biomass N:P ratio, that is, at a much lower ratio than current deposition ratios 4 . Several important ecosystem processes such as the energy and element transfers through trophic levels have also been related to these changes in organism's N:P ratios 30 (Fig. 4) (see details in Supplementary Tables S1-S18).…”

“…Future projections of nitrogen emissions suggest an expansion of the area with high anthropogenic nitrogen deposition and high deposited N:P ratios from the populated temperate regions of the Northern Hemisphere into tropical regions 6 . The stoichiometry of these deposits currently presents a molar N:P deposition ratio in the range 44-47 over land, more than twice the current molar ratio in terrestrial plants (22)(23)(24)(25)(26)(27)(28)(29)(30) and of 114-370 over the oceans, which is 10-20 times the current molar ratio in marine plankton (B16, the Redfield ratio) 4 . These unbalanced nutrient inputs are very likely to alter the environment and the life it supports.…”

“…The burning of fossil fuels, and the formation of nitrogen oxides, has resulted in a widespread increase in the deposition of nitrogen, especially around densely populated areas. Globally, the deposition of reactive nitrogen from fossil fuel burning amounts to [25][26][27][28][29][30][31][32][33] Tg N per year (ref. 4).…”

Biodiversity maintenance in food webs with regulatory environmental feedbacks

“…However, ecosystem function beyond the ''who-eats-whom'' of food-web dynamics is important to food-web studies (Moorcroft, 2003;Pascual, 2005) and potentially, as in the context of our work, to species persistence. While studies including biogeochemical considerations and ecological stoichiometric constraints (DeAngelis, 1992;Elser et al, 1998;Moe et al, 2005;Schlesinger, 1997;Sterner and Elser, 2002) do place organisms in dynamic physical-chemical environments, effects on multiple trophic level food-web dynamics are not typically addressed: small, often analytically tractable, systems are in focus (Daufresne and Loreau, 2001a, b;Grover, 2003;Hall et al, 2006;Kuijper et al, 2004;Loladze et al, 2004). We still lack a basic understanding of how environmental feedbacks impact the dynamics and persistence of structurally realistic food webs.…”