为了揭示高山杜鹃种群生存潜力和濒危原因,以西南特有濒危植物大王杜鹃(Rhododendron rex subsp.rex)为研究对象,通过对云南省轿子雪山和小百草岭2个大王杜鹃自然种群的野外植株胸径及数量的调查,采用空间代替时间的方法建立大王杜鹃种...为了揭示高山杜鹃种群生存潜力和濒危原因,以西南特有濒危植物大王杜鹃(Rhododendron rex subsp.rex)为研究对象,通过对云南省轿子雪山和小百草岭2个大王杜鹃自然种群的野外植株胸径及数量的调查,采用空间代替时间的方法建立大王杜鹃种群的径级结构、静态生命表并绘制种群存活曲线,阐明其种群的结构特征,利用种群数量动态预测和时间序列预测来分析种群未来的发展趋势。结果表明:(1)云南轿子雪山和小百草岭两个样地大王杜鹃均表现出第Ⅰ~Ⅱ龄级个体不足的现象,尽管两个样地内大王杜鹃种群仍表现为稳定型种群,但其均对外界干扰具有很高的敏感性。(2)大王杜鹃存活曲线在云南轿子雪山和小百草岭2个样地都趋于Deevey-Ⅱ型,个体平均生存能力的期望值均在幼年(Ⅰ和Ⅱ龄级)个体中最大,死亡率和消失率曲线的变化趋势基本一致。(3)时间序列预测分析表明,云南轿子雪山大王杜鹃种群在未来2、4、6年龄级后总体均呈下降趋势,种群面临衰退危险;小百草岭样地内,大王杜鹃种群总体上呈增长趋势,种群具有一定的恢复潜力。建议加强大王杜鹃自然种群生境的保护与管理从而维持其种群自然更新与发展的能力。展开更多
34-, 17-, 4-, 1.5-year old natural algal crusts were collected from Shapotou Scientific Station of the Chinese Academy of Sciences, 40-day old field and greenhouse artificial algal crusts were in situ developed in the...34-, 17-, 4-, 1.5-year old natural algal crusts were collected from Shapotou Scientific Station of the Chinese Academy of Sciences, 40-day old field and greenhouse artificial algal crusts were in situ developed in the same sandy soil and the same place (37°27’N, 104°57’E). Their different cohesions both against wind force and pressure were measured respectively by a sandy wind-tunnel experiment and a penetrometer. On the basis of these algal crusts, the cementing mechanism was revealed from many subjects and different levels. The results showed that in the indoor artificial crusts with the weakest cohesion bunchy algal filaments were distributed in the surface of the crusts, produced few extracellular polymers (EPS), the binding capacity of the crusts just accomplished by mechanical bundle of algal filaments. For field crusts, most filaments grew toward the deeper layers of algal crusts, secreted much more EPS, and when organic matter content was more than 2.4 times of chlorophyll a, overmuch organic展开更多
Biological soil crusts(BSCs)have important ecological functions in arid and semiarid lands,but they remain poorly understood in terms of the changes in microbial communities during BSC succession under in situ field c...Biological soil crusts(BSCs)have important ecological functions in arid and semiarid lands,but they remain poorly understood in terms of the changes in microbial communities during BSC succession under in situ field conditions.Here,454 pyrosequencing was used to assess the microbial community composition of four BSC types in the Tengger Desert of China:alga,lichen(cyanolichen and green alga-lichen),and moss crusts,representing early,middle,and final successional stages of BSCs,respectively.The results showed the highest diversity of microbial communities inhabiting lichen crusts,whereas the lowest diversity was observed in moss crusts.Five phyla,Proteobacteria,Actinobacteria,Cyanobacteria,Bacteroidetes,and Acidobacteria,accounted for about 72% to 87%of total prokaryotic sequences in different BSCs.The most abundant eukaryotic microorganism was Ascomycota,accounting for 47%to 93%of the total eukaryotic sequences.Along the succession of BSCs,the abundance of photoautotrophic Cyanobacteria,Chlorophyta,and Bacillariophyta declined,and that of heterotrophic microorganisms such as bacteria and fungi increased.Statistical analysis showed clear divergency of microbial taxa at the class level among the different successional stages of BSCs.The clustering results at class level showed that the moss crusts were the farthest from the rest in prokaryotic composition;the alga crusts were the most different in terms of eukaryotic microorganisms and the two kinds of lichen crusts were relatively closer in both compositions.Ordination analysis showed that the main variations of community structure among BSCs could be explained best by the abundance of Cyanobacteria and Ascomycota and by physiochemical properties of BSCs,including mechanical composition,moisture,and electrical conductivity.In conclusion,our results indicate that Cyanobacteria and Ascomycota likely play an important role in the evolution of BSC structure and functions and highlight the importance of environmental factors in shaping microbial community structures of BSCs in the Tengger Desert of China.展开更多
Changing the ratio of light-harvesting pigments was regarded as an efficient way to improve the photosyn-thesis rate in microalgae, but the underlying mechanism is still unclear. In the present study, a mutant of Anab...Changing the ratio of light-harvesting pigments was regarded as an efficient way to improve the photosyn-thesis rate in microalgae, but the underlying mechanism is still unclear. In the present study, a mutant of Anabeana simensis (called SP) was selected from retrieved satellite cul-tures. Several parameters related with photosynthesis, such as the growth, photosynthesis rate, the content of photosyn-thetic pigment, low temperature fluorescence spectrum (77K) and electron transport rate, were compared with those of the wild type. It was found that the change in the ratio of light-harvesting pigments in the mutant led to more efficient light energy transfer and usage in mutant than in the wild type. This may be the reason why the mutant had higher photosynthesis and growth rates.展开更多
In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to invest...In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert.In the study region,water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake,and was mainly taken up by a water vapor adsorption mechanism;the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%).The formation of crusts promoted water uptake,but the increased uptake did not occur immediately after inoculation or crusts formation.The water taken up from the atmosphere increased significantly from day 15 after inoculation,and the soil water content was markedly enhanced from day 20 after inoculation.It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts,and these variables increased even during dry periods when some algae are likely to have died.展开更多
文摘为了揭示高山杜鹃种群生存潜力和濒危原因,以西南特有濒危植物大王杜鹃(Rhododendron rex subsp.rex)为研究对象,通过对云南省轿子雪山和小百草岭2个大王杜鹃自然种群的野外植株胸径及数量的调查,采用空间代替时间的方法建立大王杜鹃种群的径级结构、静态生命表并绘制种群存活曲线,阐明其种群的结构特征,利用种群数量动态预测和时间序列预测来分析种群未来的发展趋势。结果表明:(1)云南轿子雪山和小百草岭两个样地大王杜鹃均表现出第Ⅰ~Ⅱ龄级个体不足的现象,尽管两个样地内大王杜鹃种群仍表现为稳定型种群,但其均对外界干扰具有很高的敏感性。(2)大王杜鹃存活曲线在云南轿子雪山和小百草岭2个样地都趋于Deevey-Ⅱ型,个体平均生存能力的期望值均在幼年(Ⅰ和Ⅱ龄级)个体中最大,死亡率和消失率曲线的变化趋势基本一致。(3)时间序列预测分析表明,云南轿子雪山大王杜鹃种群在未来2、4、6年龄级后总体均呈下降趋势,种群面临衰退危险;小百草岭样地内,大王杜鹃种群总体上呈增长趋势,种群具有一定的恢复潜力。建议加强大王杜鹃自然种群生境的保护与管理从而维持其种群自然更新与发展的能力。
基金This work was supported by The Key Project of The Chinese Academy of Sciences (Grant No. KZ952-51-207)the National Natural Science Foundation of China (Grant No. 30070154, 30170022) Mid-youth Natural Science Foundation of Gansu (Grant No.YS-011-A25-0
文摘34-, 17-, 4-, 1.5-year old natural algal crusts were collected from Shapotou Scientific Station of the Chinese Academy of Sciences, 40-day old field and greenhouse artificial algal crusts were in situ developed in the same sandy soil and the same place (37°27’N, 104°57’E). Their different cohesions both against wind force and pressure were measured respectively by a sandy wind-tunnel experiment and a penetrometer. On the basis of these algal crusts, the cementing mechanism was revealed from many subjects and different levels. The results showed that in the indoor artificial crusts with the weakest cohesion bunchy algal filaments were distributed in the surface of the crusts, produced few extracellular polymers (EPS), the binding capacity of the crusts just accomplished by mechanical bundle of algal filaments. For field crusts, most filaments grew toward the deeper layers of algal crusts, secreted much more EPS, and when organic matter content was more than 2.4 times of chlorophyll a, overmuch organic
基金supported by the National Natural Science Foundation of China (Nos. 31170464, 41573111, and 31300322)
文摘Biological soil crusts(BSCs)have important ecological functions in arid and semiarid lands,but they remain poorly understood in terms of the changes in microbial communities during BSC succession under in situ field conditions.Here,454 pyrosequencing was used to assess the microbial community composition of four BSC types in the Tengger Desert of China:alga,lichen(cyanolichen and green alga-lichen),and moss crusts,representing early,middle,and final successional stages of BSCs,respectively.The results showed the highest diversity of microbial communities inhabiting lichen crusts,whereas the lowest diversity was observed in moss crusts.Five phyla,Proteobacteria,Actinobacteria,Cyanobacteria,Bacteroidetes,and Acidobacteria,accounted for about 72% to 87%of total prokaryotic sequences in different BSCs.The most abundant eukaryotic microorganism was Ascomycota,accounting for 47%to 93%of the total eukaryotic sequences.Along the succession of BSCs,the abundance of photoautotrophic Cyanobacteria,Chlorophyta,and Bacillariophyta declined,and that of heterotrophic microorganisms such as bacteria and fungi increased.Statistical analysis showed clear divergency of microbial taxa at the class level among the different successional stages of BSCs.The clustering results at class level showed that the moss crusts were the farthest from the rest in prokaryotic composition;the alga crusts were the most different in terms of eukaryotic microorganisms and the two kinds of lichen crusts were relatively closer in both compositions.Ordination analysis showed that the main variations of community structure among BSCs could be explained best by the abundance of Cyanobacteria and Ascomycota and by physiochemical properties of BSCs,including mechanical composition,moisture,and electrical conductivity.In conclusion,our results indicate that Cyanobacteria and Ascomycota likely play an important role in the evolution of BSC structure and functions and highlight the importance of environmental factors in shaping microbial community structures of BSCs in the Tengger Desert of China.
基金The work was supported by the Chinese Academy of Sciences(Grant No.KSCX-SW-322)Project of Chinese Manned Spaceflight.
文摘Changing the ratio of light-harvesting pigments was regarded as an efficient way to improve the photosyn-thesis rate in microalgae, but the underlying mechanism is still unclear. In the present study, a mutant of Anabeana simensis (called SP) was selected from retrieved satellite cul-tures. Several parameters related with photosynthesis, such as the growth, photosynthesis rate, the content of photosyn-thetic pigment, low temperature fluorescence spectrum (77K) and electron transport rate, were compared with those of the wild type. It was found that the change in the ratio of light-harvesting pigments in the mutant led to more efficient light energy transfer and usage in mutant than in the wild type. This may be the reason why the mutant had higher photosynthesis and growth rates.
基金supported by the National Natural Science Foundation of China (Grant Nos. 30770395 and 30870470)partly by the Wuhan Science and Technology Bureau and the Inner Mongolia Planning Committee on high-tech industrialization
文摘In arid and semiarid areas,water uptake (non-rainfall water) serves as an important water source for plants,biological soil crusts,insects and small animals.In this study,a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert.In the study region,water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake,and was mainly taken up by a water vapor adsorption mechanism;the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%).The formation of crusts promoted water uptake,but the increased uptake did not occur immediately after inoculation or crusts formation.The water taken up from the atmosphere increased significantly from day 15 after inoculation,and the soil water content was markedly enhanced from day 20 after inoculation.It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts,and these variables increased even during dry periods when some algae are likely to have died.
