To examine changes in surface soil quality over time in Populus×xiaohei shelterbelts,we collected soil samples from five shelterbelts of different ages and also from former cropland left fallow for 25 years.Twent...To examine changes in surface soil quality over time in Populus×xiaohei shelterbelts,we collected soil samples from five shelterbelts of different ages and also from former cropland left fallow for 25 years.Twenty-one surface soil(0–20 cm)properties were measured,and variation in soil quality was assessed using one-way ANOVAs and multiple comparison tests.Based on this analysis,16 soil indexes were used in a model evaluating soil quality,with each index given weight as determined by the correlation coefficient.Compared with the control,the postmature forest had greater soil moisture content but lower bulk density(P<0.05).The mature forest also had higher soil pH,total organic carbon,alkali-hydrolyzed nitrogen,available phosphorus,and biomass nitrogen content,but reduced nitrate-nitrogen and total phosphorus content than the control(P<0.05).Total porosity was highly positively correlated with aeration,nitrate-nitrogen,alkali-hydrolyzed nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen.Soil total organic carbon,ammonium nitrogen,nitrate-nitrogen,alkali-hydrolyzed nitrogen,total nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen were all strongly correlated.In the soil quality evaluation model,total organic carbon was assigned the highest weight and total potassium content the lowest.The soil quality index was lowest in the near-mature forest and greatest in the postmature forest.Generally,soil quality in P opulus×xiaohei shelterbelts varied with age and was higher in the 10–20 cm versus 0–10 cm soil layer.After a single forest generation,surface soil quality was significantly improved.展开更多
Phrynocephalus vlangalii are widely distributed on Tibetan plateau spanning diverse altitudes and habitats. In the present study, P vlangalii were exposed to 8% oxygen concentration in a hypoxic chamber for 6 weeks. T...Phrynocephalus vlangalii are widely distributed on Tibetan plateau spanning diverse altitudes and habitats. In the present study, P vlangalii were exposed to 8% oxygen concentration in a hypoxic chamber for 6 weeks. Then the body temperature （Tb）, standard metabolic rate （SMR）, heart rate and metabolic enzyme activities of the lizards were measured at 20℃ and 30℃. The results indicated that hypoxia exposure decreased Tb, SMR and heart rate. Lactate dehydrogenase （LDH） activity of 8% 02 group became significant elevated in liver and skeletal muscle compared with control group at 20℃, but descended significantly in heart. Using electrophoresis we found that LDH contains five isozymes （LDH1, LDH2, LDH3, LDH4 and LDH5） and are expressed specifically in liver, skeletal muscle and heart. Citrate synthase （CS） activity in the liver also decreased at 20℃ and 30℃. No significant difference of CS activity was found between the two groups in skeletal muscle and heart.展开更多
基金supported by Forestry Industry Research Special Funds for Public Welfare Projects(2014040202-01)。
文摘To examine changes in surface soil quality over time in Populus×xiaohei shelterbelts,we collected soil samples from five shelterbelts of different ages and also from former cropland left fallow for 25 years.Twenty-one surface soil(0–20 cm)properties were measured,and variation in soil quality was assessed using one-way ANOVAs and multiple comparison tests.Based on this analysis,16 soil indexes were used in a model evaluating soil quality,with each index given weight as determined by the correlation coefficient.Compared with the control,the postmature forest had greater soil moisture content but lower bulk density(P<0.05).The mature forest also had higher soil pH,total organic carbon,alkali-hydrolyzed nitrogen,available phosphorus,and biomass nitrogen content,but reduced nitrate-nitrogen and total phosphorus content than the control(P<0.05).Total porosity was highly positively correlated with aeration,nitrate-nitrogen,alkali-hydrolyzed nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen.Soil total organic carbon,ammonium nitrogen,nitrate-nitrogen,alkali-hydrolyzed nitrogen,total nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen were all strongly correlated.In the soil quality evaluation model,total organic carbon was assigned the highest weight and total potassium content the lowest.The soil quality index was lowest in the near-mature forest and greatest in the postmature forest.Generally,soil quality in P opulus×xiaohei shelterbelts varied with age and was higher in the 10–20 cm versus 0–10 cm soil layer.After a single forest generation,surface soil quality was significantly improved.
基金supported by the National Natural Science Foundation of China(Nos.31272313 and 31472005 to Q.CHEN)Fundamental Research Funds for the Central Universities(lzujbky-2015-81 to X,L.Tang)
文摘Phrynocephalus vlangalii are widely distributed on Tibetan plateau spanning diverse altitudes and habitats. In the present study, P vlangalii were exposed to 8% oxygen concentration in a hypoxic chamber for 6 weeks. Then the body temperature （Tb）, standard metabolic rate （SMR）, heart rate and metabolic enzyme activities of the lizards were measured at 20℃ and 30℃. The results indicated that hypoxia exposure decreased Tb, SMR and heart rate. Lactate dehydrogenase （LDH） activity of 8% 02 group became significant elevated in liver and skeletal muscle compared with control group at 20℃, but descended significantly in heart. Using electrophoresis we found that LDH contains five isozymes （LDH1, LDH2, LDH3, LDH4 and LDH5） and are expressed specifically in liver, skeletal muscle and heart. Citrate synthase （CS） activity in the liver also decreased at 20℃ and 30℃. No significant difference of CS activity was found between the two groups in skeletal muscle and heart.
