We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of po...We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine （Pinus sylvestris var. mongolica） plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil （up to 80 cm in this study）. Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.展开更多
Aims Alien plant invasion has become a major global environmental issue,causing severe economic and ecological damages.Severe invasions have been reported in some regions of China.However,most studies have been conduc...Aims Alien plant invasion has become a major global environmental issue,causing severe economic and ecological damages.Severe invasions have been reported in some regions of China.However,most studies have been conducted at local and provincial levels,and the overall degree of invasion in natural forests across China remains unclear.Here,we explored the biogeographic patterns and their environmental and socioeconomic controls of the invaded alien woody plants in natural forests across the country.Methods We compiled the data of 3573 natural forest plots across the China's Mainland and mapped spatial distribution of alien woody plant invasion.We also used logistic regression models to identify the key socioeconomic and environmental factors that were associated with the observed invasion patterns.Important Findings We found that only 271 plots among 3573 natural forest plots were invaded by alien woody plants,accounting for 7.58%of all plots.Among all 2825 woody plant species across all plots surveyed,only 5 alien species(0.177%)were found.Both human activities and climate factors were related to the observed invasion patterns.Since China’s natural forests are mostly located in remote mountainous areas with limited human disturbance,alien woody plant invasions are less than those reported in North America and Europe.However,with the development of transportation and increased economic activities in mountainous areas,more invasions by alien plants may be expected in the future.Therefore,proactive management and policy making are desired to prevent or slow down the invasion processes.展开更多
Alnus trabeeulosa, a rhizobia-nodulating tree, was introduced into the Chongxi tidal wetland in the Yangtze River estuary of China to increase the biodiversity of plants and restore tidal wetland functions. However, t...Alnus trabeeulosa, a rhizobia-nodulating tree, was introduced into the Chongxi tidal wetland in the Yangtze River estuary of China to increase the biodiversity of plants and restore tidal wetland functions. However, the effect of the introduced plant on soil bacterial communities and restoration outcomes remains unknown. In this study, the rhizosphere bacterial community structure and diversity were compared between Phragrnites australis monospecific community and A. trabeculosa-P, australis mixed communities, aiming to assess whether A. trabeculosa influenced the rhizosphere bacterial communities of P. australis and to investigate whether different taxonomic groups within a soil community may respond similarly to the presence of an introduced exotic plant. Among the 14 phylogenetic phyla detected, Proteobacteria and Acidobacteria were the dominant bacterial taxa in the rhizosphere. Phylogenetic analysis of the predominant Proteobacteria showed that the clones from the rhizosphere soils of A. trabeculosa and P. australis in A. trabeculosa-P, australis mixed communities were more diverse than those in the rhizosphere soil of P. australis in P. australis monospecific community. The rhizosphere community in the wetland potentially included active microbial community related to carbon, nitrogen, and sulfur cycling in the Yangtze River estuary. The rhizosphere soil of P. australis in A. trabeculosa-P, australis mixed communities exhibited the highest Shannon diversity index （Hr） and Simpson diversity index （l/D） （H = 4.52, 1/D = 253）. Correspondence analyses revealed that the bacterial community structures were altered after A. trabeculosa was introduced.展开更多
Members of the Chinese delegation celebrate after Beijing wins the bid to host the 2022 Winter Olympics at the128th Session of the International Olympic Committee in Kuala Lumpur,Malaysia,on July 31.Beijing beat its o...Members of the Chinese delegation celebrate after Beijing wins the bid to host the 2022 Winter Olympics at the128th Session of the International Olympic Committee in Kuala Lumpur,Malaysia,on July 31.Beijing beat its only competitor Almaty,Kazakhstan,by 44 votes to 40 with one abstention.President Xi Jinping expressed Chinese people’s passion for the Winter Games in a video message during Beijing’s presentation.The Chinese capital launched a joint bid for the Games in November 2013 with Zhangjiakou in neighboring Hebei Province.It becomes the first city in the world to host both the Summer and Winter Olympics.展开更多
基金the National Science Foundation of China (30770339)
文摘We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine （Pinus sylvestris var. mongolica） plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil （up to 80 cm in this study）. Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.
基金This research was supported by the National Natural Science Foundation of China(31988102).
文摘Aims Alien plant invasion has become a major global environmental issue,causing severe economic and ecological damages.Severe invasions have been reported in some regions of China.However,most studies have been conducted at local and provincial levels,and the overall degree of invasion in natural forests across China remains unclear.Here,we explored the biogeographic patterns and their environmental and socioeconomic controls of the invaded alien woody plants in natural forests across the country.Methods We compiled the data of 3573 natural forest plots across the China's Mainland and mapped spatial distribution of alien woody plant invasion.We also used logistic regression models to identify the key socioeconomic and environmental factors that were associated with the observed invasion patterns.Important Findings We found that only 271 plots among 3573 natural forest plots were invaded by alien woody plants,accounting for 7.58%of all plots.Among all 2825 woody plant species across all plots surveyed,only 5 alien species(0.177%)were found.Both human activities and climate factors were related to the observed invasion patterns.Since China’s natural forests are mostly located in remote mountainous areas with limited human disturbance,alien woody plant invasions are less than those reported in North America and Europe.However,with the development of transportation and increased economic activities in mountainous areas,more invasions by alien plants may be expected in the future.Therefore,proactive management and policy making are desired to prevent or slow down the invasion processes.
基金supported by the National Natural Science Foundation of China (Nos. 41101230, 40771203 and 40871243)the Shanghai Municipal Science and Technology Commission of China (No. 10231201600)
文摘Alnus trabeeulosa, a rhizobia-nodulating tree, was introduced into the Chongxi tidal wetland in the Yangtze River estuary of China to increase the biodiversity of plants and restore tidal wetland functions. However, the effect of the introduced plant on soil bacterial communities and restoration outcomes remains unknown. In this study, the rhizosphere bacterial community structure and diversity were compared between Phragrnites australis monospecific community and A. trabeculosa-P, australis mixed communities, aiming to assess whether A. trabeculosa influenced the rhizosphere bacterial communities of P. australis and to investigate whether different taxonomic groups within a soil community may respond similarly to the presence of an introduced exotic plant. Among the 14 phylogenetic phyla detected, Proteobacteria and Acidobacteria were the dominant bacterial taxa in the rhizosphere. Phylogenetic analysis of the predominant Proteobacteria showed that the clones from the rhizosphere soils of A. trabeculosa and P. australis in A. trabeculosa-P, australis mixed communities were more diverse than those in the rhizosphere soil of P. australis in P. australis monospecific community. The rhizosphere community in the wetland potentially included active microbial community related to carbon, nitrogen, and sulfur cycling in the Yangtze River estuary. The rhizosphere soil of P. australis in A. trabeculosa-P, australis mixed communities exhibited the highest Shannon diversity index （Hr） and Simpson diversity index （l/D） （H = 4.52, 1/D = 253）. Correspondence analyses revealed that the bacterial community structures were altered after A. trabeculosa was introduced.
文摘Members of the Chinese delegation celebrate after Beijing wins the bid to host the 2022 Winter Olympics at the128th Session of the International Olympic Committee in Kuala Lumpur,Malaysia,on July 31.Beijing beat its only competitor Almaty,Kazakhstan,by 44 votes to 40 with one abstention.President Xi Jinping expressed Chinese people’s passion for the Winter Games in a video message during Beijing’s presentation.The Chinese capital launched a joint bid for the Games in November 2013 with Zhangjiakou in neighboring Hebei Province.It becomes the first city in the world to host both the Summer and Winter Olympics.
