Response of Gobi Desert soil to the establishment of sea buckthorn(Hippophae rhamnoides)plantationsOA

Vegetation restoration is a critical approach for improving soil quality in arid ecosystems,yet its effects on soil extracellular enzyme activities(EEAs),stoichiometric relationships,and nutrient dynamics in the Gobi Desert remain poorly understood.This study aimed to address this knowledge gap by analyzing a chronosequence of three stand ages(3,11,and 14 a)of artificial sea buckthorn(Hippophae rhamnoides L.)plantations in the 170th Regiment of the 9th Agricultural Division of the Xinjiang Production and Construction Corps,China.Three 20 m×20 m quadrats were established for each restoration stage in early to mid-August 2024.Soil samples were collected in 0-10,10-20,and 20-30 cm soil layers within each quadrat using a five-point method,to explore the ecological changes in Gobi Desert soil throughout the vegetation restoration.The results indicated that soil organic carbon(SOC),particulate organic carbon(POC),dissolved organic carbon(DOC),mineral-associated organic carbon(MAOC),total nitrogen(TN),and microbial biomass carbon(MBC),nitrogen(MBN),and phosphorus(MBP)all significantly increased in the 0-10 cm soil layer during vegetation restoration.In the 10-20 cm soil layer,MAOC and TN significantly increased during vegetation restoration,while in the 20-30 cm soil layer,MAOC,TN,MBN,and MBP significantly increased.Concurrently,the activities of key enzymes(β-1,4-glucosidase andβ-1,4-N-acetylglucosaminidase)involved in carbon(C)and nitrogen(N)cycling were also the highest in the 14-year-old plantation in the 0-10 cm soil layer.Further analysis of enzymatic stoichiometry indicated a shift in microbial resource allocation,with significant increases in the C-N and C-phosphorus(P)ratios of EEAs,whereas the N-P ratio remained relatively stable.The drivers of these stoichiometric ratios varied with soil depth:in the 0-20 cm soil layer,the C-N and C-P ratios of EEAs were mainly influenced by soil C content,whereas the N-P ratio was not regulated by any factors.In the 20-30 cm soil layer,the C-N and C-P ratios of EEAs were mainly influenced by soil C,N,and microbial biomass content,whereas the N-P ratio was mainly affected by TP and pH.Overall,the establishment of sea buckthorn plantations,especially over a 14-a period,significantly improved Gobi Desert soil quality by enhancing nutrient content,stimulating microbial activity,and modulating extracellular enzyme strategies.These findings underscore the considerable C sequestration potential and ecological benefits of targeted artificial afforestation in arid land restoration.