Thinning is an effective management step for sustainable forest development,yet less attention is paid to the restoration of soil microbiota after thinning.In this study,both abundant and rare soil microbial communiti...Thinning is an effective management step for sustainable forest development,yet less attention is paid to the restoration of soil microbiota after thinning.In this study,both abundant and rare soil microbial communities(i.e.,bacterial,fungal),were evaluated under various thinning treatments in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu using Mi Seq sequencing.Thinning did not significantly change either abundant or rare bacterial and fungal community composition,but affected their alpha diversity.The Shannon–Wiener indexes of rare fungal taxa under medium thinning were significantly lower than in the light thinning(P<0.05 level).Xanthobacteraceae dominated the abundant bacterial taxa,and Saitozyma and Mortierlla the abundant fungal taxa.The most common rare bacterial taxa varied;there was no prevalent rare fungal taxa under different thinnings.In addition,soil available nitrogen,total phosphorus,and p H had significant effects on rare bacterial taxa.Nutrients,especially available phosphorus,but not nitrogen,affected abundant and rare soil fungi.The results indicate that soil properties rather than plant factors affect abundant and rare microbial communities in soils of mixed stands.Thinning,through mediating soil properties,influences both abundant and rare bacterial and fungal communities in the mixed C.lanceolata and S.tzumu stand.展开更多
Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine...Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.展开更多
Globally, SARS-CoV-2 has infected 3,113,447 people and killed 216,930 as of April 29, 2020. Identifying populations vulnerable to infection and their disease progression is critical to mitigating the negative impacts ...Globally, SARS-CoV-2 has infected 3,113,447 people and killed 216,930 as of April 29, 2020. Identifying populations vulnerable to infection and their disease progression is critical to mitigating the negative impacts on healthcare systems. Recent studies have shown that angiotensin converting enzyme 2 (ACE2) is the receptor for SARS-CoV-2 to enter human cells (Zhou et al., 2020), raising the possibility that a higher ACE2 expression level could facilitate SARS-CoV-2infection.展开更多
为提高滤波器组多载波(Filter Bank Multicarrier,FBMC)系统在低信噪比下的定时同步准确率和抗频偏性能,基于FBMC系统与正交频分复用(Orthogonal Frequency Division Multiple,OFDM)系统的相似性,对OFDM系统定时同步中的Park测度函数进...为提高滤波器组多载波(Filter Bank Multicarrier,FBMC)系统在低信噪比下的定时同步准确率和抗频偏性能,基于FBMC系统与正交频分复用(Orthogonal Frequency Division Multiple,OFDM)系统的相似性,对OFDM系统定时同步中的Park测度函数进行改进并引入到FBMC系统中。利用共轭对称结构能够提高定时精度和加权处理能够更好地抵抗频偏影响的特点设计同步序列,进行共轭对称和加权处理。仿真结果表明,基于改进序列的Park算法相较共轭对称序列的TR1算法,其信噪比提前3 dB达到了100%定时准确率,实现了低信噪比下的高精度定时同步,且具有更强的抗频偏性能;相较原Park算法,相同信噪比下,改进序列的Park算法的频偏均方差(Mean Square Error,MSE)也小于原Park算法的频偏MSE,抗频偏性能表现更优。展开更多
基金the Sino-German Cooperation Forestry Major Scientific Research Project(zdczhz2021ky09)the National Natural Science Foundation of China(31971487 and 42277245).
文摘Thinning is an effective management step for sustainable forest development,yet less attention is paid to the restoration of soil microbiota after thinning.In this study,both abundant and rare soil microbial communities(i.e.,bacterial,fungal),were evaluated under various thinning treatments in a mixed stand of Cunninghamia lanceolata and Sassafras tzumu using Mi Seq sequencing.Thinning did not significantly change either abundant or rare bacterial and fungal community composition,but affected their alpha diversity.The Shannon–Wiener indexes of rare fungal taxa under medium thinning were significantly lower than in the light thinning(P<0.05 level).Xanthobacteraceae dominated the abundant bacterial taxa,and Saitozyma and Mortierlla the abundant fungal taxa.The most common rare bacterial taxa varied;there was no prevalent rare fungal taxa under different thinnings.In addition,soil available nitrogen,total phosphorus,and p H had significant effects on rare bacterial taxa.Nutrients,especially available phosphorus,but not nitrogen,affected abundant and rare soil fungi.The results indicate that soil properties rather than plant factors affect abundant and rare microbial communities in soils of mixed stands.Thinning,through mediating soil properties,influences both abundant and rare bacterial and fungal communities in the mixed C.lanceolata and S.tzumu stand.
基金supported by the National Natural Science Foundation of China (42071073,31971487)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021366)+2 种基金Guangxi Key Research and Development Program (AB17129009)the Hechi Distinguished Expert Program to Fuping Zengthe Guangxi Bagui Scholarship Program to Dejun Li。
文摘Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.
基金supported by the National Key R&D Program of China (2018YFA0507503)。
文摘Globally, SARS-CoV-2 has infected 3,113,447 people and killed 216,930 as of April 29, 2020. Identifying populations vulnerable to infection and their disease progression is critical to mitigating the negative impacts on healthcare systems. Recent studies have shown that angiotensin converting enzyme 2 (ACE2) is the receptor for SARS-CoV-2 to enter human cells (Zhou et al., 2020), raising the possibility that a higher ACE2 expression level could facilitate SARS-CoV-2infection.
文摘为提高滤波器组多载波(Filter Bank Multicarrier,FBMC)系统在低信噪比下的定时同步准确率和抗频偏性能,基于FBMC系统与正交频分复用(Orthogonal Frequency Division Multiple,OFDM)系统的相似性,对OFDM系统定时同步中的Park测度函数进行改进并引入到FBMC系统中。利用共轭对称结构能够提高定时精度和加权处理能够更好地抵抗频偏影响的特点设计同步序列,进行共轭对称和加权处理。仿真结果表明,基于改进序列的Park算法相较共轭对称序列的TR1算法,其信噪比提前3 dB达到了100%定时准确率,实现了低信噪比下的高精度定时同步,且具有更强的抗频偏性能;相较原Park算法,相同信噪比下,改进序列的Park算法的频偏均方差(Mean Square Error,MSE)也小于原Park算法的频偏MSE,抗频偏性能表现更优。
