The circum-lake zone of the Qinghai Lake is one of the most serious regions of desertification on the Qinghai-Tibetan Plateau. Based on Remote Sensing （RS） and Geographical Information System （GIS） techniques, the...The circum-lake zone of the Qinghai Lake is one of the most serious regions of desertification on the Qinghai-Tibetan Plateau. Based on Remote Sensing （RS） and Geographical Information System （GIS） techniques, the four sets of remote sensing images acquired in 1976, 1987, 1995, and 2006 were selected to conduct thematic information extraction in 14,300 km2 of land in the circum-lake zone using the Earth Resource Data Analysis System （ERDAS） image and information processing function. In the meantime the off-site interpretation and filed check-correction methods were used to recon- struct the temporal-spatial dynamic changes and differentiation patterns of land desertification in the circum-lake zone in the past 30 years, and based on this, the developmental trend of land desertification in the next 20 years was predicted. The results of the study show that in the past 30 years land desertification in the region experienced a continuous fluctuation between rapid- and slow-development processes in time, while in space it exhibited a few small patchy distributions or sporadic distributions in many places while at the same time, four large sand-dominated distributions stood out and evolved into a circum-lake belt differentiation pattern with a lakeside dike as the connecting line. Due to the integrated effects of climate changes, human activities and artificial rehabilitation, land desertification area in the region in the next 20 years will exhibit an increasing trend in the first 15 years and then increase at a slower rate, and afterward occur in a reverse, decreasing trend.展开更多
The decomposition of deadwood is a crucial process for the accumulation and sequestration of soil organic carbon (SOC) in forest ecosystems. However, the response of SOC to different decay classes of deadwood and the ...The decomposition of deadwood is a crucial process for the accumulation and sequestration of soil organic carbon (SOC) in forest ecosystems. However, the response of SOC to different decay classes of deadwood and the underlying mechanisms remain poorly understood. Here, we investigated the dynamics of SOC, soil properties, extracellular enzyme activities, and phospholipid fatty acid biomarkers across five decay classes (ranging from 1 to 5) of Masson pine (Pinus massoniana Lamb.) downed deadwood in a subtropical–temperate ecotone forest in Central China. Our results revealed a nonlinear response pattern of SOC along the deadwood decomposition gradient, with the maximum value at the decay class 4. Soil available nitrogen content, bacterial biomass, fungal biomass, the ratio of fungal-to-bacterial biomass, cellulase, activity and ligninase activity all increased with the intensification of deadwood decay, while soil pH decreased. The increase in SOC content was associated with a direct positive effect of bacteria and both direct and indirect positive effects of fungi by cellulose activity, but ligninase activity showed no significant relationship with SOC content. These findings suggest that cellulose and microbial biomass are key determinants of soil C formation and sequestration during deadwood decomposition. This study highlights the importance of the nonlinear response of SOC to deadwood decay, providing valuable insights for predicting future carbon-climate feedbacks.展开更多
共和盆地出露的风成沉积较好地记录亚洲季风和西风环流的演化信息,是研究古气候环境的良好载体。本文对共和盆地茫拉剖面512 cm厚的风成沉积的粒度数据进行参数化端元分析,结合粒度敏感指标和色度指标阐释了各端元揭示的物源特征、环境...共和盆地出露的风成沉积较好地记录亚洲季风和西风环流的演化信息,是研究古气候环境的良好载体。本文对共和盆地茫拉剖面512 cm厚的风成沉积的粒度数据进行参数化端元分析,结合粒度敏感指标和色度指标阐释了各端元揭示的物源特征、环境意义及末次盛冰期以来共和盆地的环境演化过程,并进一步分析了其与季风环流系统的协同性。结果表明:剖面沉积物粒度组分可分解为3个端元:EM1为湿沉降的高空西风搬运的远源粉尘物质,间接反映区域干湿变化;EM2为低空风系作用下以悬移和跃移形式短距离搬运的中远源细颗粒沉积;EM3为蠕移或跃移形式短距离搬运的近源粗颗粒沉积。EM2与EM3指示相反,但共同反映冬季风的强弱。区域环境演化可划分为3个阶段:末次盛冰期阶段(22.27~17.59 ka BP),气候冷干,受控于西风环流;末次冰消期阶段(17.59~10 ka BP),气候冷干-温润,冷暖波动,夏季风和西风交替控制;中晚全新世阶段(8.49 ka BP以来),气候由温润向冷干发展,夏季风与西风此消彼长。展开更多
Aims Fire and atmospheric nitrogen(N)deposition have the potential to influence growth and productivity of forest canopy.However,their impacts on photosynthesis and growth traits of understory plants in forests remain...Aims Fire and atmospheric nitrogen(N)deposition have the potential to influence growth and productivity of forest canopy.However,their impacts on photosynthesis and growth traits of understory plants in forests remain largely unexplored.This study was conducted to examine the effects of burning and N addition on foliar N content,net photosynthesis and growth traits of three dominant shrub species(Vitex negundo,Lindera glauca and Symplocos chinensis)in a temperate forest in Central China.Methods The experiment used a pair-nested design,with four treatments(control,burning,N addition and burning plus N addition)and five replicates.Leaf mass area(LMA),area-based concentrations of foliar N and chlorophyll(N_(area) and Chl_(area)),net photosynthesis(A_(n)),stomatal conductance(g_(s)),maximum photosynthetic rate(A_(max))and maximal carboxylation rate(V_(cmax)),basal diameter,height and branch length(BL)of the three species were measured.Important Findings Across the three species,burning stimulated LMA,N_(area),Chl_(area),A_(n),g_(s),A_(max) and V_(cmax),and consequently enhanced basal diam-eter,height and BL.Nitrogen addition increased A_(n) and gs but did not affect LMA,N_(area),Chl_(area),A_(max),V_(cmax),basal diameter,height or BL.However,N addition strengthened the positive effects of burning on g_(s),V_(cmax),A_(n) and BL.The findings indicate the primary role of light resources in determining plant photosynthesis and growth of understory shrub species after fire and highlight that understory plants should be considered in projection of biomass accumulation and productivity of forests under environmental perturbations.展开更多
To the Editor:Bladder cancer is the most common malignant tumor of the urinary system in the Asian population.In China,it is reported 80,000 new cases each year with an increasing incidence every year.Among these case...To the Editor:Bladder cancer is the most common malignant tumor of the urinary system in the Asian population.In China,it is reported 80,000 new cases each year with an increasing incidence every year.Among these cases,75%are of non-muscle invasive bladder cancer(NMIBC).In muscular invasive bladder cancer(MIBC)and NMIBC patients,radical cystectomy is considered as a primary approach of treatment due to the higher risk of tumor progression.Furthermore.展开更多
基金supported by National Natural Science Foundations of China (Grant Nos. 40761026 and 41161036)the grant of the Outstanding Youth Foundation Project Program of the Northwest Normal University (No. NWNU-LKON-10-34)
文摘The circum-lake zone of the Qinghai Lake is one of the most serious regions of desertification on the Qinghai-Tibetan Plateau. Based on Remote Sensing （RS） and Geographical Information System （GIS） techniques, the four sets of remote sensing images acquired in 1976, 1987, 1995, and 2006 were selected to conduct thematic information extraction in 14,300 km2 of land in the circum-lake zone using the Earth Resource Data Analysis System （ERDAS） image and information processing function. In the meantime the off-site interpretation and filed check-correction methods were used to recon- struct the temporal-spatial dynamic changes and differentiation patterns of land desertification in the circum-lake zone in the past 30 years, and based on this, the developmental trend of land desertification in the next 20 years was predicted. The results of the study show that in the past 30 years land desertification in the region experienced a continuous fluctuation between rapid- and slow-development processes in time, while in space it exhibited a few small patchy distributions or sporadic distributions in many places while at the same time, four large sand-dominated distributions stood out and evolved into a circum-lake belt differentiation pattern with a lakeside dike as the connecting line. Due to the integrated effects of climate changes, human activities and artificial rehabilitation, land desertification area in the region in the next 20 years will exhibit an increasing trend in the first 15 years and then increase at a slower rate, and afterward occur in a reverse, decreasing trend.
基金supported by grants from the National Natural Science Foundation of China (32201362)the Henan Province Science and Technology Research Project (242102321157)the Research and Development Funds of Hubei University of Science and Technology (BK202404)。
文摘The decomposition of deadwood is a crucial process for the accumulation and sequestration of soil organic carbon (SOC) in forest ecosystems. However, the response of SOC to different decay classes of deadwood and the underlying mechanisms remain poorly understood. Here, we investigated the dynamics of SOC, soil properties, extracellular enzyme activities, and phospholipid fatty acid biomarkers across five decay classes (ranging from 1 to 5) of Masson pine (Pinus massoniana Lamb.) downed deadwood in a subtropical–temperate ecotone forest in Central China. Our results revealed a nonlinear response pattern of SOC along the deadwood decomposition gradient, with the maximum value at the decay class 4. Soil available nitrogen content, bacterial biomass, fungal biomass, the ratio of fungal-to-bacterial biomass, cellulase, activity and ligninase activity all increased with the intensification of deadwood decay, while soil pH decreased. The increase in SOC content was associated with a direct positive effect of bacteria and both direct and indirect positive effects of fungi by cellulose activity, but ligninase activity showed no significant relationship with SOC content. These findings suggest that cellulose and microbial biomass are key determinants of soil C formation and sequestration during deadwood decomposition. This study highlights the importance of the nonlinear response of SOC to deadwood decay, providing valuable insights for predicting future carbon-climate feedbacks.
文摘共和盆地出露的风成沉积较好地记录亚洲季风和西风环流的演化信息,是研究古气候环境的良好载体。本文对共和盆地茫拉剖面512 cm厚的风成沉积的粒度数据进行参数化端元分析,结合粒度敏感指标和色度指标阐释了各端元揭示的物源特征、环境意义及末次盛冰期以来共和盆地的环境演化过程,并进一步分析了其与季风环流系统的协同性。结果表明:剖面沉积物粒度组分可分解为3个端元:EM1为湿沉降的高空西风搬运的远源粉尘物质,间接反映区域干湿变化;EM2为低空风系作用下以悬移和跃移形式短距离搬运的中远源细颗粒沉积;EM3为蠕移或跃移形式短距离搬运的近源粗颗粒沉积。EM2与EM3指示相反,但共同反映冬季风的强弱。区域环境演化可划分为3个阶段:末次盛冰期阶段(22.27~17.59 ka BP),气候冷干,受控于西风环流;末次冰消期阶段(17.59~10 ka BP),气候冷干-温润,冷暖波动,夏季风和西风交替控制;中晚全新世阶段(8.49 ka BP以来),气候由温润向冷干发展,夏季风与西风此消彼长。
基金This work was financially supported by the National Natural Science Foundation of China(31430015).
文摘Aims Fire and atmospheric nitrogen(N)deposition have the potential to influence growth and productivity of forest canopy.However,their impacts on photosynthesis and growth traits of understory plants in forests remain largely unexplored.This study was conducted to examine the effects of burning and N addition on foliar N content,net photosynthesis and growth traits of three dominant shrub species(Vitex negundo,Lindera glauca and Symplocos chinensis)in a temperate forest in Central China.Methods The experiment used a pair-nested design,with four treatments(control,burning,N addition and burning plus N addition)and five replicates.Leaf mass area(LMA),area-based concentrations of foliar N and chlorophyll(N_(area) and Chl_(area)),net photosynthesis(A_(n)),stomatal conductance(g_(s)),maximum photosynthetic rate(A_(max))and maximal carboxylation rate(V_(cmax)),basal diameter,height and branch length(BL)of the three species were measured.Important Findings Across the three species,burning stimulated LMA,N_(area),Chl_(area),A_(n),g_(s),A_(max) and V_(cmax),and consequently enhanced basal diam-eter,height and BL.Nitrogen addition increased A_(n) and gs but did not affect LMA,N_(area),Chl_(area),A_(max),V_(cmax),basal diameter,height or BL.However,N addition strengthened the positive effects of burning on g_(s),V_(cmax),A_(n) and BL.The findings indicate the primary role of light resources in determining plant photosynthesis and growth of understory shrub species after fire and highlight that understory plants should be considered in projection of biomass accumulation and productivity of forests under environmental perturbations.
基金the Zhejiang Provincial Medical and Health Science and Technology(No.WKJ-ZJ-1929)。
文摘To the Editor:Bladder cancer is the most common malignant tumor of the urinary system in the Asian population.In China,it is reported 80,000 new cases each year with an increasing incidence every year.Among these cases,75%are of non-muscle invasive bladder cancer(NMIBC).In muscular invasive bladder cancer(MIBC)and NMIBC patients,radical cystectomy is considered as a primary approach of treatment due to the higher risk of tumor progression.Furthermore.
