Mathematical Analysis of a Chemotaxis-Type Model of Soil Carbon Dynamic

The goal of this paper is to study the mathematical properties of a new model of soil carbon dynamics which is a reaction-diffusion system with a chemotactic term, with the aim to account for the formation of soil aggregations in the bacterial and microorganism spatial organization(hot spot in soil). This is a spatial and chemotactic version of MOMOS(Modelling Organic changes by Micro-Organisms of Soil), a model recently introduced by M. Pansu and his group. The authors present here two forms of chemotactic terms, first a"classical" one and second a function which prevents the overcrowding of microorganisms.They prove in each case the existence of a nonnegative global solution, and investigate its uniqueness and the existence of a global attractor for all the solutions.

Climate warming suppresses abundant soil fungal taxa and reduces soil carbon efflux in a semi-arid grassland

Soil microorganisms critically affect the ecosystem carbon(C)balance and C-climate feedback by directly controlling organic C decomposition and indirectly regulating nutrient availability for plant C fixation.However,the effects of climate change drivers such as warming,precipitation change on soil microbial communities,and C dynamics remain poorly understood.Using a long-term field warming and precipitation manipulation in a semi-arid grassland on the Loess Plateau and a complementary incubation experiment,here we show that warming and rainfall reduction differentially affect the abundance and composition of bacteria and fungi,and soil C efflux.Warming significantly reduced the abundance of fungi but not bacteria,increasing the relative dominance of bacteria in the soil microbial community.In particular,warming shifted the community composition of abundant fungi in favor of oligotrophic Capnodiales and Hypocreales over potential saprotroph Archaeorhizomycetales.Also,precipitation reduction increased soil total microbial biomass but did not significantly affect the abundance or diversity of bacteria.Furthermore,the community composition of abundant,but not rare,soil fungi was significantly correlated with soil CO_(2) efflux.Our findings suggest that alterations in the fungal community composition,in response to changes in soil C and moisture,dominate the microbial responses to climate change and thus control soil C dynamics in semi-arid grasslands.