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971.
A species of the genus Gonoclostera Butler, 1877, G.fangi sp.nov., from Yunnan, China is described in the present paper. Generic diagnosis and list of world species, as well as the photos of adults and genitalia of the new species are also provided. 相似文献
972.
973.
In water-limited regions, oases are important localities for maintaining ecological biodiversity and supporting social and
economic development. For oases situated by the side of rivers, variability of streamflow is often considered as a dominant
factor influencing the vulnerability of oases forest, whereas other factors receive much less attention. Here we argue that
ecological and hydrological processes creating spatial habitat heterogeneity and particularly the change of habitat structure
through time are critical aspects when assessing vulnerability of oasis forest. This is demonstrated by dendroecological studies
of a dynamic landscape in Ejina Oasis in the lower reach of Heihe River, the second largest inland river in China. Our results
show that radial growth of euphrates poplar trees in Ejina Oasis did not follow the variation of streamflow coming from the
middle reach, and the poplar tree-ring growth did not change in the same way from one site to the other. An index of multi-directional
change (MDCi) is defined from tree-ring data to describe the change in spatial habitats through time. We propose that the decreasing trend
of MDCi indices since the 1950s is related to persistently increasing human activities, whereas high-frequency variability in MDCi indices is related to frequent and strong local disturbances such as windstorms as well as human activities that directly
cause changes in streamflow. The results obtained from this study have potentially broad implications for identifying dryland
ecosystems that are at risk or susceptible to change, and for making spatially explicit decisions for rational utilization
of water resources. 相似文献
974.
Purpose
Cadmium (Cd) is a toxic heavy metal, accumulated in soil by anthropogenic activities and has serious effects on soil microbial activities in contaminated soils. Moreover, there is a lack of reliable data on the effects of Cd in the soil-plant system, since most of the information on Cd-microorganism interactions in soils are based on sewage sludge without plants. The main objective of this study was to assess the effects of Cd on soil microbial activities and community structure during growth of plant. 相似文献975.
976.
977.
978.
Jiwan P Palta 《Potato Research》2010,53(4):267-275
Calcium plays a major role in plant growth and development and in the maintenance and modulation of various cell functions,
especially related to membrane structure and function and to cell wall structure. Calcium stabilizes cell membranes by bridging
polar head groups of phospholipids at the membrane surface. Calcium is also an integral part of the cell wall where it provides
stable intra-molecular linkages between pectin molecules, resulting in cell wall rigidity. A change in the cytosolic calcium
concentration is also known to provide a cellular signal that regulates metabolism and mediates plant responses to stresses. 相似文献
979.
Kimihiko Hyakumura 《Small-Scale Forestry》2010,9(3):349-367
A progressive part of protected area management program in Lao PDR is a land and forest allocation program which contains
critical elements that delegate right of land and forest use to local people. This study analyzes the gap between the original
intent of the program and its actual implementation by local officials in Phou Xang He protected area, and discusses policy
issues that need to be addressed. It appears that several types of non-compliance with regulations by local people have occurred,
with local officials tacitly ignoring infractions. By switching viewpoints, however, it appears that the local officials permit
these infractions as a way of allowing local people to secure their livelihoods. As constraints on the realities of land and
forest use vary widely in and around villages in different locales, there is a need for government to allow local officials
flexibility in implementing policies. 相似文献
980.