Changbai Mountain,central in the distribution of Pinus koraiensis,supports a virgin Korean pine forest with vertical gradient distribution.Soil extracellular enzyme activity(EEA) and enzyme stoichiometry(ES) are relia...Changbai Mountain,central in the distribution of Pinus koraiensis,supports a virgin Korean pine forest with vertical gradient distribution.Soil extracellular enzyme activity(EEA) and enzyme stoichiometry(ES) are reliable indicators of the energy and nutrients utilized by microbial communities and of soil nutrient changes.We measured four representative soil EEAs(sucrase,cellulase,urease,acid phosphatase) at two soil layers(A:0-5 cm and B:5-10 cm)beneath Korean pine forest at five elevations on Changbai Mountain during growing season.The vertical and seasonal variations of EEAs were analyzed by soil enzyme stoichiometry to quantify the role of soil microorganism in the nutrient cycling process.The activities of four soil extracellular enzymes and the ratios of enzyme activity to soil microbial biomass carbon(EA/SMBC) did not vary with elevation.The first partition point of multiple regression trees was in September,and the second branch was split by elevation.Seasonal change had more influence on soil enzyme activity(A layer:75.6%;B layer:71.3%) than did change in elevation(A layer:7.8%;B layer:7.5%).Over one entire growing season,both vector length and vector angle were unchanged by elevation,but varied significantly by month.Among the soil physicochemical factors,available phosphorus and pH were the main factors affecting the four soil EE As.The ratio of basal area of the coniferous tree to broad-leaved tree species(S_(con)/S_(br)),soil microbial biomass carbon(MBC) and nitrogen(MBN) influenced the four soil EE As.The results of vector analysis revealed that C and N sources were generally sufficient,but P was limiting(vector angle> 45°).The vector angle for September was significantly higher than for other months.This result verified that phosphorus was the limiting factor affecting soil microorganism function in nutrient metabolism and cycling.Soil enzyme stoichiometry proved to be an efficient index for quantifying soil microorganismmediated nutrient cycling in the Korean pine ecosystem.展开更多
Soil microorganisms play a key role in soil organic matter dynamics, nutrient cycling, and soil fertility maintenance in forest ecosystems, and they are influenced by stand age and soil depth. However, few studies hav...Soil microorganisms play a key role in soil organic matter dynamics, nutrient cycling, and soil fertility maintenance in forest ecosystems, and they are influenced by stand age and soil depth. However, few studies have simultaneously considered these two factors. In this study, we measured soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil basal respiration (SBR) rate, and potential extracellular enzyme activity (EEA) in soil to a depth of 60 cm under 10-, 30-, and 40-year-old Scots pine (Pinus sylvestris var. mongolica) stands (Y10, Y30, and Y40, respectively) in plantations in northern China in 2011. Soil water content (SWC), soil pH, soil organic carbon (SOC), and soil total nitrogen (STN) were also measured to explore their effects on soil microbial indices across different stand ages and soil depths. Our results showed that SMBC, SMBN, and the SBR rate were generally higher for the Y30 stand than for the Y10 and Y40 stands. Potential EEA, except forα-glucosidase, decreased significantly with increasing stand age. Soil organic carbon,STN, SWC, and soil pH explained 67%of the variation in soil microbial attributes among the three stand ages. For the same stand age, soil microbial biomass and the SBR rate decreased with soil depth. Lower microbial biomass, lower SBR rate, and lower EEA for the mature Y40 stand indicate lower substrate availability for soil microorganisms, lower soil quality, and lower microbial adaptability to the environment. Our results suggest that changes in soil quality with stand age should be considered when determining the optimum rotation length of plantations and the best management practices for afforestation programs.展开更多
基金supported by the National Natural Science Foundation of China (No.31670496)。
文摘Changbai Mountain,central in the distribution of Pinus koraiensis,supports a virgin Korean pine forest with vertical gradient distribution.Soil extracellular enzyme activity(EEA) and enzyme stoichiometry(ES) are reliable indicators of the energy and nutrients utilized by microbial communities and of soil nutrient changes.We measured four representative soil EEAs(sucrase,cellulase,urease,acid phosphatase) at two soil layers(A:0-5 cm and B:5-10 cm)beneath Korean pine forest at five elevations on Changbai Mountain during growing season.The vertical and seasonal variations of EEAs were analyzed by soil enzyme stoichiometry to quantify the role of soil microorganism in the nutrient cycling process.The activities of four soil extracellular enzymes and the ratios of enzyme activity to soil microbial biomass carbon(EA/SMBC) did not vary with elevation.The first partition point of multiple regression trees was in September,and the second branch was split by elevation.Seasonal change had more influence on soil enzyme activity(A layer:75.6%;B layer:71.3%) than did change in elevation(A layer:7.8%;B layer:7.5%).Over one entire growing season,both vector length and vector angle were unchanged by elevation,but varied significantly by month.Among the soil physicochemical factors,available phosphorus and pH were the main factors affecting the four soil EE As.The ratio of basal area of the coniferous tree to broad-leaved tree species(S_(con)/S_(br)),soil microbial biomass carbon(MBC) and nitrogen(MBN) influenced the four soil EE As.The results of vector analysis revealed that C and N sources were generally sufficient,but P was limiting(vector angle> 45°).The vector angle for September was significantly higher than for other months.This result verified that phosphorus was the limiting factor affecting soil microorganism function in nutrient metabolism and cycling.Soil enzyme stoichiometry proved to be an efficient index for quantifying soil microorganismmediated nutrient cycling in the Korean pine ecosystem.
基金This study was supported by projects of the National Natural Science Foundation of China(Nos.31972939,31630009 and 31670325)the National Basic Research Pro-gram of China(No.2016YFC0500701)+1 种基金the Research Fund of the State Key Laboratory of Soil and Sustainable Agri-culture,Nanjing Institute of Soil Science,Chinese Academy of Sciences(No.Y412201439)the University Con-struction Projects from the Central Authorities in Beiing of China.
文摘Soil microorganisms play a key role in soil organic matter dynamics, nutrient cycling, and soil fertility maintenance in forest ecosystems, and they are influenced by stand age and soil depth. However, few studies have simultaneously considered these two factors. In this study, we measured soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil basal respiration (SBR) rate, and potential extracellular enzyme activity (EEA) in soil to a depth of 60 cm under 10-, 30-, and 40-year-old Scots pine (Pinus sylvestris var. mongolica) stands (Y10, Y30, and Y40, respectively) in plantations in northern China in 2011. Soil water content (SWC), soil pH, soil organic carbon (SOC), and soil total nitrogen (STN) were also measured to explore their effects on soil microbial indices across different stand ages and soil depths. Our results showed that SMBC, SMBN, and the SBR rate were generally higher for the Y30 stand than for the Y10 and Y40 stands. Potential EEA, except forα-glucosidase, decreased significantly with increasing stand age. Soil organic carbon,STN, SWC, and soil pH explained 67%of the variation in soil microbial attributes among the three stand ages. For the same stand age, soil microbial biomass and the SBR rate decreased with soil depth. Lower microbial biomass, lower SBR rate, and lower EEA for the mature Y40 stand indicate lower substrate availability for soil microorganisms, lower soil quality, and lower microbial adaptability to the environment. Our results suggest that changes in soil quality with stand age should be considered when determining the optimum rotation length of plantations and the best management practices for afforestation programs.
