In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various m...In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.展开更多
Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreact...Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor （MBR） technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilm than the sludge during the establishment ofbiofilms at low transmembrane pressure （TMP）. Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.展开更多
Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbi...Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; MarineGroupⅠand Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,MarineGroupⅠ; and might be the primary driving force for the seasonal variation of the microbial community.展开更多
悦读·明其义The power of community service社区服务的力量Community service,often called volunteering,is a valuable way to contribute to society and make a positive difference.It involves offering time and skills wi...悦读·明其义The power of community service社区服务的力量Community service,often called volunteering,is a valuable way to contribute to society and make a positive difference.It involves offering time and skills without expecting money in return,focusing on helping those in need or improving the environment.For high school students,participating in such activities not only benefits communities but also builds character and practical experience that textbooks alone cannot teach.展开更多
On the basis of a long-term（30 years） field experiment that involved four rotation systems, rice-rice-winter fallow（RRF）, rice-rice-ryegrass（RRG）, rice-rice-rape（RRP）, and rice-rice-milk vetch（RRV）, this stu...On the basis of a long-term（30 years） field experiment that involved four rotation systems, rice-rice-winter fallow（RRF）, rice-rice-ryegrass（RRG）, rice-rice-rape（RRP）, and rice-rice-milk vetch（RRV）, this study described the effects of green manure on the microbial communities in the red paddy soils using 454 pyrosequencing for the 16 S r RNA gene. The Chao1 richness and non-parametric Shannon＇s index increased in all soil samples that received green manure treatments. The communities＇ structures with the green manure applications were significantly dissimilar from that under the winter fallow. Using Metastats tests, many genera in the RRG, RRP and RRV soils were significantly different from those in the RRF soil, including a number of genera that functioned in the nitrogen and sulfur cycles. Analyses of the genera with these functions revealed the shifts in microbial ecosystem functions after long-term green manuring. Changes in the microbial communities increased the ammonium supply and decreased the soil acidification in green-manure-amended soils. Together, these data suggested powerful effects of green manure on both the microbial communities and the biogeochemical cycle driven by the shifts in bacterial functional groups.展开更多
Recently, complex networks have attracted considerable research attention. Community detection is an important problem in the field of complex networks and is useful in a variety of applications such as information pr...Recently, complex networks have attracted considerable research attention. Community detection is an important problem in the field of complex networks and is useful in a variety of applications such as information propagation, link prediction, recommendation, and marketing. In this study, we focus on discovering overlapping community structures by using link partitions. We propose a Latent Dirichlet Allocation （LDA）-Based Link Partition （LBLP） method, which can find communities with an adjustable range of overlapping. This method employs the LDA model to detect link partitions, which can calculate the community belonging factor for each link. On the basis of this factor, link partitions with bridge links can be found efficiently. We validate the effectiveness of the proposed solution by using both real-world and synthesized networks. The experimental results demonstrate that the approach can find a meaningful and relevant link community structure.展开更多
基金financially supported by the National Key Basic Research Development Program (No.2009CB119200)the Forestry Public Welfare Industry Scientific Research Project (No.200904029-3)
文摘In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.
基金supported by a research grant (MEWRC651/ 06/177) from the Environment and Water Industry Programme Office of Singapore
文摘Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor （MBR） technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilm than the sludge during the establishment ofbiofilms at low transmembrane pressure （TMP）. Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.
基金supported by a General Project granted by the National Natural Science Foundation of China (No. 51178002)
文摘Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; MarineGroupⅠand Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,MarineGroupⅠ; and might be the primary driving force for the seasonal variation of the microbial community.
文摘悦读·明其义The power of community service社区服务的力量Community service,often called volunteering,is a valuable way to contribute to society and make a positive difference.It involves offering time and skills without expecting money in return,focusing on helping those in need or improving the environment.For high school students,participating in such activities not only benefits communities but also builds character and practical experience that textbooks alone cannot teach.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest of China(201103005)the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(2013–2017)
文摘On the basis of a long-term（30 years） field experiment that involved four rotation systems, rice-rice-winter fallow（RRF）, rice-rice-ryegrass（RRG）, rice-rice-rape（RRP）, and rice-rice-milk vetch（RRV）, this study described the effects of green manure on the microbial communities in the red paddy soils using 454 pyrosequencing for the 16 S r RNA gene. The Chao1 richness and non-parametric Shannon＇s index increased in all soil samples that received green manure treatments. The communities＇ structures with the green manure applications were significantly dissimilar from that under the winter fallow. Using Metastats tests, many genera in the RRG, RRP and RRV soils were significantly different from those in the RRF soil, including a number of genera that functioned in the nitrogen and sulfur cycles. Analyses of the genera with these functions revealed the shifts in microbial ecosystem functions after long-term green manuring. Changes in the microbial communities increased the ammonium supply and decreased the soil acidification in green-manure-amended soils. Together, these data suggested powerful effects of green manure on both the microbial communities and the biogeochemical cycle driven by the shifts in bacterial functional groups.
基金the National Key Basic Research and Department (973) Program of China(No. 2013CB329603)the National Natural Science Foundation of China (Nos. 61074128 and 71231002)
文摘Recently, complex networks have attracted considerable research attention. Community detection is an important problem in the field of complex networks and is useful in a variety of applications such as information propagation, link prediction, recommendation, and marketing. In this study, we focus on discovering overlapping community structures by using link partitions. We propose a Latent Dirichlet Allocation （LDA）-Based Link Partition （LBLP） method, which can find communities with an adjustable range of overlapping. This method employs the LDA model to detect link partitions, which can calculate the community belonging factor for each link. On the basis of this factor, link partitions with bridge links can be found efficiently. We validate the effectiveness of the proposed solution by using both real-world and synthesized networks. The experimental results demonstrate that the approach can find a meaningful and relevant link community structure.
