Soil acidity, ecological stoichiometry and allometric scaling in grassland food webs

Abstract

The factors regulating the structure of food webs are a central focus of community and ecosystem ecology, as trophic interactions among species have important impacts on nutrient storage and cycling in many ecosystems. For soil invertebrates in grassland ecosystems in the Netherlands, the site-specific slopes of the faunal biomass to organism body mass relationships reflected basic biochemical and biogeochemical processes associated with soil acidity and soil C : N : P stoichiometry. That is, the higher the phosphorus availability in the soil, the higher, on average, the slope of the faunal biomass size spectrum (i.e., the higher the biomass of large-bodied invertebrates relative to the biomass of small invertebrates). While other factors may also be involved, these results are consistent with the growth rate hypothesis from biological stoichiometry that relates phosphorus demands to ribosomal RNA and protein production. Thus our data represent the first time that ecosystem phosphorus availability has been associated with allometry in soil food webs (supporting information available online). Our results have broad implications, as soil invertebrates of different size have different effects on soil processes.

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

“…Second, increased N:P availability ratio in soils and waters favours the slow-growing species with high optimal N:P ratios at the expense of the fast-growing species with lower optimal N:P ratio 34 . Third, by favouring species with slower growth rates, food sources with higher N:P ratios decrease the rates of energy transfer through food webs 40 , favouring shorter trophic webs with fewer predators 41 , thus potentially decreasing biodiversity. Fourth, in phosphorus-limited zones of the coastal waters, zooplankton (for example, copepods) adapt their feeding behaviour to counteract the resource limitation in selecting higher phosphorus-containing organisms (for example, ciliates) rather than nutrient-limited phytoplankton 42 .…”

Agricultural land use decouples soil nutrient cycles in a subtropical riparian wetland in China

“…crop harvesting and weathering) (Sardans et al, 2012a). Land-use changes due to agronomic practices and livestock production generate soil stoichiometric shifts in forests (Falkengren-Gerup et al, 2006;Sardans and Peñuelas, 2013), shrublands , grasslands (Mulder and Elser, 2009) and steppes (Jiao et al, 2013). The status of the C:N:P ratio in wetland soil under different intensities of human disturbance, however, remains unknown.…”

Lower P contents and more widespread terpene presence in old Bornean than in young Hawaiian tropical plant species guilds

“…C:N:P content stoichiometry is related to several ecological and ecophysiological strategies such as growth rate (Elser et al 1996, Elser and Hamilton 2007, Mulder and Elser 2009, and to community biotic relationships such as plantherbivore interactions (Schade et al 2003, Urabe et al 2003, Perkins et al 2004, Carline et al 2005. Long-term changes in ecosystem C:N:P stoichiometry could result from soil changes and species adaptation processes and it is worthwhile to investigate this important trait in tropical forests of different ages.…”