Effects of desertification on the C:N:P stoichiometry of soil, microbes, and extracellular enzymes in a desert grassland

Abstract

Aims In order to discuss the underlying mechanism of desertification effect on the ecological stoichiometry of soil, microbes and extracellular enzymes, we studied the changes of soil, soil microbial and extracellular enzyme C:N:P stoichiometry during the desertification process in the desert grassland in Yanchi County, China. Methods The “space-for-time” method was used. Important findings The results demonstrated that: (1) Soil C, N, P contents and soil C:P, N:P significantly decreased, but soil C:N gradually increased with increasing desertification. (2) Soil microbial biomass C (MBC):soil microbial biomass P (MBP), soil microbial biomass N (MBN):MBP and soil β-1,4-glucosidase (BG):β-1,4-N-acetylglucosaminidase (NAG) gradually decreased, soil BG:alkaline phosphatase (AP) and NAG:AP basically showed an increasing trend with increasing desertification. (3) Desertification increased the soil microbial carbon use efficiency (CUE C : N and CUE C : P ) gradually, while soil microbial nitrogen use efficiency (NUE N : C ) and soil microbial phosphorus use efficiency (PUE P : C ) basically decreased. (4) Soil, soil microbial and soil extracellular enzyme C:N stoichiometry (C:N, MBC:MBN, BG:NAG) were significantly negatively correlated with the soil, soil microbial and extracellular enzyme N:P stoichiometry (N:P, MBN:MBP, NAG:AP), the soil and extracellular enzymes C:N (C:N, BG:NAG) were significantly positively correlated with the soil and extracellular enzymes C:P (C:P, BG:AP). Soil N:P was significantly positively correlated with the soil MBN:MBP, but was significantly negatively correlated with the soil NAG:AP. The analysis demonstrated that soil microbial biomass and extracellular enzyme activity changed with soil nutrient during the desertification process in the desert grassland. The co-variation relationship between soil nutrient and C:N:P stoichiometry of microbial-extracellular enzyme provides a theoretical basis for understanding the underlying mechanism of C, N, P cycling in the soil-microbial system in desert grasslands.