Introduction:In Central Himalaya,anthropogenic activities have led to the widespread replacement of Banj oak(Quercus leucotrichophora)forest by Chir pine(Pinus roxburghii)for decades.This study was conducted to determ...Introduction:In Central Himalaya,anthropogenic activities have led to the widespread replacement of Banj oak(Quercus leucotrichophora)forest by Chir pine(Pinus roxburghii)for decades.This study was conducted to determine how natural Banj oak,Chir pine,and mixed oak-pine forest would differ in soil microbial biomass and soil nutrients.Soil microbial biomass nitrogen(SMBN)and phosphorus(SMBP),soil organic carbon(SOC)total nitrogen(TN),and total phosphorus(TP)in the 0 to 15 cm soil layer were investigated in the Central Himalayan region in the stands of Banj oak,mixed oak-pine,and Chir pine forest.Results:The SMBN and SMBP were significantly higher in Banj oak and mixed oak-pine forest as compared to Chir pine forest.The ratios of SMBN to TN(SMBN/TN)and SMBP to TP(SMBP/TP)were significantly higher in the Chir pine forest,indicating that in this forest,the proportion of microbial biomass N and P to total soil N and P was higher as compared to Banj oak forest.A similar pattern of variation was found in relation to season across the forests,all with an apparent peak in the rainy season.Conclusion:These results indicate that low microbial biomass N and P may be one of the reasons to create a nutrient poor site in Chir pine forest.The collection of pine litter by local people also impairs the return of nutrients to the soil and makes it difficult for Banj oak to re-invade areas occupied by Chir pine.This calls for cautions in large-scale conversions of the Banj oak forests to coniferous plantations as a forest management practice on concerns of sustaining soil productivity.展开更多
Rehabilitation of farmland improves the local eco-environmental conditions.But to what extent this transformation influences soil microbial properties is less known.In our study we compared variations in soil microbia...Rehabilitation of farmland improves the local eco-environmental conditions.But to what extent this transformation influences soil microbial properties is less known.In our study we compared variations in soil microbial attributes following changes in land-use types to understand the influence of altered soil properties on microbial biomass and their community structure using chloroform fumigation extraction method and phospholipid fatty acid(PLFA)analysis.For this purpose,3 agricultural(AL)(farmland,apple orchard and 2 years abandoned land)and 4 rehabilitated lands(RL)of various vegetations grassland,shrubland,mixed forest(Amorpha fruticosa and Pinus tabuliformis Carr.)and forest(Robinia pseudoacacia)were selected.Our results showed higher soil organic carbon(SOC)contents in RL soils(forest>mixed forest>grassland>shrub land)than that in AL soils.In RL soils,soil microbial biomass and abundance of group specific PLFA were significantly higher than those in AL soils.Under different land-use types,microbial community was bacteria dominated over fungi.The microbial physiological indices(G^(+)/G^(-),cyc/prec and S/M)indicated decreased environmental stress in RL soils in comparison with AL soils.In loess soils,SOC and total N correlated positively(p<0.05)with microbial biomass C,N and P and also with fungal and bacterial PLFA,indicating a positive microbial mediation in improving soil fertility.Taking together,our findings suggest that land rehabilitation,especially Robinia pseudoacacia planation,improves overall edaphic conditions and accelerates soil microbial biomass accumulation in local regions.展开更多
文摘Introduction:In Central Himalaya,anthropogenic activities have led to the widespread replacement of Banj oak(Quercus leucotrichophora)forest by Chir pine(Pinus roxburghii)for decades.This study was conducted to determine how natural Banj oak,Chir pine,and mixed oak-pine forest would differ in soil microbial biomass and soil nutrients.Soil microbial biomass nitrogen(SMBN)and phosphorus(SMBP),soil organic carbon(SOC)total nitrogen(TN),and total phosphorus(TP)in the 0 to 15 cm soil layer were investigated in the Central Himalayan region in the stands of Banj oak,mixed oak-pine,and Chir pine forest.Results:The SMBN and SMBP were significantly higher in Banj oak and mixed oak-pine forest as compared to Chir pine forest.The ratios of SMBN to TN(SMBN/TN)and SMBP to TP(SMBP/TP)were significantly higher in the Chir pine forest,indicating that in this forest,the proportion of microbial biomass N and P to total soil N and P was higher as compared to Banj oak forest.A similar pattern of variation was found in relation to season across the forests,all with an apparent peak in the rainy season.Conclusion:These results indicate that low microbial biomass N and P may be one of the reasons to create a nutrient poor site in Chir pine forest.The collection of pine litter by local people also impairs the return of nutrients to the soil and makes it difficult for Banj oak to re-invade areas occupied by Chir pine.This calls for cautions in large-scale conversions of the Banj oak forests to coniferous plantations as a forest management practice on concerns of sustaining soil productivity.
基金funded by the National Natural Science Foundation of China(41701317)Science and Technology Service Network Initiative,Chinese Academy of Sciences(2017)Open-Funds of Scientific Research Programs of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau(A314021402-2002).
文摘Rehabilitation of farmland improves the local eco-environmental conditions.But to what extent this transformation influences soil microbial properties is less known.In our study we compared variations in soil microbial attributes following changes in land-use types to understand the influence of altered soil properties on microbial biomass and their community structure using chloroform fumigation extraction method and phospholipid fatty acid(PLFA)analysis.For this purpose,3 agricultural(AL)(farmland,apple orchard and 2 years abandoned land)and 4 rehabilitated lands(RL)of various vegetations grassland,shrubland,mixed forest(Amorpha fruticosa and Pinus tabuliformis Carr.)and forest(Robinia pseudoacacia)were selected.Our results showed higher soil organic carbon(SOC)contents in RL soils(forest>mixed forest>grassland>shrub land)than that in AL soils.In RL soils,soil microbial biomass and abundance of group specific PLFA were significantly higher than those in AL soils.Under different land-use types,microbial community was bacteria dominated over fungi.The microbial physiological indices(G^(+)/G^(-),cyc/prec and S/M)indicated decreased environmental stress in RL soils in comparison with AL soils.In loess soils,SOC and total N correlated positively(p<0.05)with microbial biomass C,N and P and also with fungal and bacterial PLFA,indicating a positive microbial mediation in improving soil fertility.Taking together,our findings suggest that land rehabilitation,especially Robinia pseudoacacia planation,improves overall edaphic conditions and accelerates soil microbial biomass accumulation in local regions.
