Stoichiometric characteristics of C,N and P in soil and litter of shrublands in karst areas of Guangxi

YUE Xiangfei; LI Yanqing; LIU Peng

doi:10.11932/karst2023y032

Abstract：This study was conducted at seven typical karst areas(Longlin,Lingyun,Donglan,Hechi,Luocheng,Rongshui and Guilin)of Guangxi,China.These areas present subtropical monsoon climate,with annual temperatures averaging from 19.27 ℃ to 20.73 ℃,and the annual rainfall averaging from 1,149.2 mm to 1,931.3 mm.This study focused on the stoichiometric characteristics and the influencing factors of organic carbon(C),nitrogen(N)and phosphorus(P)in soil and litter of typical karst areas.By field sampling and laboratory experiment,the stoichiometric characteristics of soil organic C,N,and P,and litter C,N and P of 63 shrub quadrats in the seven typical karst areas were investigated.Besides,the correlation between the variation in stoichiometric characteristics of soil and environmental factors were analyzed. The research findings show that:(1)the mean content of C,N and P in 0-40 cm soil was 31.90 g·kg-1,3.95 g·kg1 and 2.65 g·kg-1,and the coefficient of variation was 40.13％,41.46％and 65.24％,respectively.The mean value of C/N,C/P and N/P was 8.10,14.82 and 7.80,and the coefficient of variation was 14.88％,48.78％and 41.33％,respectively.The values of C/N,C/P and N/P in 0-20 cm soil were slightly higher than those in 20-40 cm.There were significant differences in soil C/N,C/P and N/P between 0-20 cm and 20-40 cm(P＞0.05).(2)There were significant correlations among the contents of soil C,N and P(P＜0.01).The stoichiometric characteristics of soil nutrients elements were significantly affected by litter N and P(PP＜0.05)which was negatively correlated with the C/N ratio of litter.There was a moderately negative correlation between mean annual precipitation and soil C and P.However,the mean annual temperature was negatively correlated with soil C,C/N and C/P,which was positively correlated with soil N. The soil C,N and P of typical karst shrubland in Guangxi presents high spatial heterogeneity,with the characteristics of low C and high P,and the litter is characterized by low C,high P,low C/P and low N/P.Litter N and P is the important factor affecting the stoichiometric characteristics of soil nutrients in shrubland of the karst area.The increase of mean annual temperature will promote the increase of soil N and decrease soil C/N,and the increase of mean annual precipitation will reduce soil C and P.Our research results have great significance for the theoretical improvement of the stoichiometric study on soil ecology,vegetation restoration in degraded karst ecosystem and the response of karst ecosystem to climate change in Southwest China.