Carbon allocation in grassland communities under drought stress followed by 14C pulse labeling

摘要: Abstract Although extreme climatic events such as drought have important consequences for belowground carbon (C) cycling, their impact on the plant-soil system of mixed plant communities is poorly understood. Our objective was to study effect C allocation and rhizosphere-mediated CO2 fluxes under three species: Lolium perenne, Festuca arundinacea Medicago sativa grown in monocultures or mixture. The conceptual approach included 14CO2 pulse labeling plants optimum water conditions order be able follow above- allocation. After 14C labeling, we traced shoots roots, soil rhizospheric CO2, dissolved organic (DOC) microbial biomass. Drought community composition significantly affected assimilate system. changed source sink relationship monocultures, which transferred a relatively larger portion assimilates roots compared sufficient plants. In contrast, mixture showed an increase when exposed drought. Under stress, root respiration reduced all except legume species. Microbial remained similar cases showing that activity less by than activity. This may explained strongly increased easily available exudates rhizodeposits conclusion, modify changes fluxes. presence species attenuates effects rhizosphere processes.