Chapter Two – Connecting the Green and Brown Worlds: Allometric and Stoichiometric Predictability of Above- and Below-Ground Networks

We examine the potential of trait-based parameters for linking above-ground and below-ground ecological networks (hereafter ‘green’ and ‘brown’ worlds) to forecast community dynamics. We examine whether the brown and green worlds can be linked into a general model by combining classic allometric scaling and elemental stoichiometry. This synthesis considers carbon, nitrogen and phosphorus-related traits, numerical abundance of component species and size distribution across trophic levels. To realize this synthesis, we have re-analyzed plant, microbial and invertebrate databases that combine physico-chemical and biological information from terrestrial ecosystems spanning the globe. We found (1) indirect evidence to suggest that the traits from above-ground and below-ground systems can be integrated in the same model and (2) strong evidence for a much greater than expected stoichiometrical plasticity of plants and microbes that has implications for the entire food web. Nitrogen and phosphorus are primary basal resource drivers and more retranslocation of P than of N from leaves will lead to higher N:P in the litter. Under nutrient-rich conditions, higher foliar concentrations of N and P are mostly accompanied by lower N:P in the litter, suggesting that less P was retranslocated. This apparent stoichiometric dichotomy could result in shifts in threshold elemental ratios critical for ecosystem functioning and has important implications for a general food-web model, given that resource C:N:P ratios reflect environmental C:N:P ratios. We discuss insights that can be gained from integrating carbon and nitrogen isotope data into trait-based predictions, and address the origin of changes in Δ13C and Δ15N fractionation values as related to consumer–resource body-mass ratios.

MULDERS Christian;  AHRESTANI Farshid;  BAHN Michael;  BOHAN David;  BONKOWSKI Michael;  GRIFFITHS Bryan;  GUICHARNAUD Rannveig Anna;  KATTGE Jens;  KROGH Paul Henning;  LAVOREL Sandra;  LEWIS Owen;  MANCINELLI Giogio;  NAEEM Shahid;  PENUELAS J.;  POORTER Hendrik;  REICH Peter;  ROSSI Loreto;  RUSCH Graciela;  SARDANS Jordi;  WRIGHT Ian; 

2014-01-08

ELSEVIER ACADEMIC PRESS INC

JRC85118

0065-2504,   

http://www.sciencedirect.com/science/article/pii/B9780124200029000020,    https://publications.jrc.ec.europa.eu/repository/handle/JRC85118,   

10.1016/B978-0-12-420002-9.00002-0,