Background Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon(SOC)sequestration.However,the dynamics and drivers of SOC in grasslands after grazing e...Background Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon(SOC)sequestration.However,the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented,especially in ecosystems with cold climates.Methods Here,we established 14 paired treatments(grazing exclusion vs.free-grazing)along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau.After six years,we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths(0–10,10–20,and 20–30 cm).Results Grazing exclusion signifcantly increased above-and belowground biomass(139.85%and 43.30%,respectively),pH(1.38%),total phosphorus(3.29%),nitrate nitrogen(18.03%),and ammonium nitrogen(17.81%),but signifcantly decreased soil bulk density(2.43%)and clay content(10.49%),particularly in 0–30 cm.Specifcally,SOC concentrations positively responded to grazing exclusion(0–10 cm)in 9 of the 14 sites evaluated.The efects of grazing exclusion on SOC concentrations were signifcantly higher in areas with a mean annual temperature(MAT)below 0℃compared to those in sites with a high MAT(>0℃).The SOC concentrations signifcantly correlated with the mean annual precipitation(MAP)in both treatments,but these correlations diminished with increasing soil depth.Ridge regression analysis showed that soil chemical properties(e.g.,total nitrogen and phosphorus)positively infuenced SOC accumulation,while MAT negatively infuenced it after grazing exclusion.Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties.Conclusions Our study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more benefcial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures.Also,humid climates promote SOC concentration in alpine grasslands.These results could help develop management practices and policies that promote sustainable grassland management.展开更多
Changes in litter quality(carbon:nitrogen,C:N)and above-ground biomass(AGB)following vegetation restoration significantly impact soil physicochemical properties,yet their effects on soil microbial metabolic limitation...Changes in litter quality(carbon:nitrogen,C:N)and above-ground biomass(AGB)following vegetation restoration significantly impact soil physicochemical properties,yet their effects on soil microbial metabolic limitations remain unclear.We measured litter quality,AGB,soil physicochemical properties,and extracellular enzyme activity(EEA)along a vegetation restoration gradient(7,14,49,70 years,and nearly climax evergreen broadleaved forests)in southern China.We also evaluated soil microbial metabolic limitations by a vector analysis of the EEA.Results revealed the soil microbial metabolisms were co-limited by C and phosphorus(P).The microbial C limitation initially decreased(before 14 years)and then increased,while the microbial P limitation initially increased(before 49 years)and then decreased.Partial least squares path modeling(PLS-PM)showed that the microbial C limitation was mainly attributed to microbial C use efficiency induced by litter quality,suggesting that microorganisms may transfer cellular energy between microbial growth and Cacquiring enzyme production.The microbial P limitation was primarily correlated with AGB-driven change in soil elements and their stoichiometry,highlighting the importance of nutrient stoichiometry and balance in microbial metabolism.The shifts between microbial C and P limitations and the strong connections of plant–soil-microbe processes during vegetation restoration revealed here will provide us with helpful information for optimal management to achieve forest restoration success.展开更多
基金supported by the Second Tibetan Plateau Scientifc Expedition and Research Program(2019QZKK0405)National Natural Science Foundation of China(U23A2002,32271725)+1 种基金Collaborative Innovation Program of Hainan University(XTCX2022STB07)start-up fund of Hainan University(KYQD(ZR)21096).
文摘Background Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon(SOC)sequestration.However,the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented,especially in ecosystems with cold climates.Methods Here,we established 14 paired treatments(grazing exclusion vs.free-grazing)along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau.After six years,we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths(0–10,10–20,and 20–30 cm).Results Grazing exclusion signifcantly increased above-and belowground biomass(139.85%and 43.30%,respectively),pH(1.38%),total phosphorus(3.29%),nitrate nitrogen(18.03%),and ammonium nitrogen(17.81%),but signifcantly decreased soil bulk density(2.43%)and clay content(10.49%),particularly in 0–30 cm.Specifcally,SOC concentrations positively responded to grazing exclusion(0–10 cm)in 9 of the 14 sites evaluated.The efects of grazing exclusion on SOC concentrations were signifcantly higher in areas with a mean annual temperature(MAT)below 0℃compared to those in sites with a high MAT(>0℃).The SOC concentrations signifcantly correlated with the mean annual precipitation(MAP)in both treatments,but these correlations diminished with increasing soil depth.Ridge regression analysis showed that soil chemical properties(e.g.,total nitrogen and phosphorus)positively infuenced SOC accumulation,while MAT negatively infuenced it after grazing exclusion.Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties.Conclusions Our study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more benefcial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures.Also,humid climates promote SOC concentration in alpine grasslands.These results could help develop management practices and policies that promote sustainable grassland management.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars(Grant No.41825020)General Program(Grant No.31870461)+3 种基金the“Hundred Talent Program”of South China Botanical Garden at the Chinese Academy of Sciences(Grant No.Y761031001)the“Young Top-notch Talent”in Pearl River talent plan of Guangdong Province(Grant No.2019QN01L763)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515012147)the China Scholarships Council(Grant No.202004910605).
文摘Changes in litter quality(carbon:nitrogen,C:N)and above-ground biomass(AGB)following vegetation restoration significantly impact soil physicochemical properties,yet their effects on soil microbial metabolic limitations remain unclear.We measured litter quality,AGB,soil physicochemical properties,and extracellular enzyme activity(EEA)along a vegetation restoration gradient(7,14,49,70 years,and nearly climax evergreen broadleaved forests)in southern China.We also evaluated soil microbial metabolic limitations by a vector analysis of the EEA.Results revealed the soil microbial metabolisms were co-limited by C and phosphorus(P).The microbial C limitation initially decreased(before 14 years)and then increased,while the microbial P limitation initially increased(before 49 years)and then decreased.Partial least squares path modeling(PLS-PM)showed that the microbial C limitation was mainly attributed to microbial C use efficiency induced by litter quality,suggesting that microorganisms may transfer cellular energy between microbial growth and Cacquiring enzyme production.The microbial P limitation was primarily correlated with AGB-driven change in soil elements and their stoichiometry,highlighting the importance of nutrient stoichiometry and balance in microbial metabolism.The shifts between microbial C and P limitations and the strong connections of plant–soil-microbe processes during vegetation restoration revealed here will provide us with helpful information for optimal management to achieve forest restoration success.
