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三种鹿茸片中氨基酸质量分数的比较 总被引:1,自引:1,他引:0
通过对东北梅花鹿茸片、新西兰鹿茸片以及东北梅花鹿茸骨片中氨基酸质量分数的比较测定,结果表明:东北梅花鹿茸片中的氨基酸质量分数高于其余两种茸片中的氨基酸质量分数,从而为合理选购和使用鹿茸片提供科学理论依据。 相似文献
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破碎化次生林斑块面积及栖息地质量对繁殖鸟类群落结构的影响 总被引:12,自引:0,他引:12
于1998~2000年夏季。运用GPS定位系统确定了12块面积范围为6.5~112.8hm。的彼此隔离的森林斑块。比较了斑块面积和栖息地质量对繁殖鸟类群落结构的影响。结果表明:不同面积斑块中繁殖鸟类的群落结构有所差异。各斑块所容纳的繁殖鸟类的物种数从4种到26种不等。鸟类物种数随着斑块面积的增大而增多。不同鸟类对斑块面积的反应并不相同,耐边缘种偏爱面积较小的斑块。而非边缘种偏爱在大面积的斑块中繁殖。斑块栖息地质量也是影响鸟类群落结构的重要因素,质量好的斑块包容的鸟类物种较多。鸟类物种丰富度与斑块质量的相关性(R2=0.67)小于与斑块面积的相关性(R2=0.88)。各斑块中的鸟类群落结构在不同年份间比较相似。栖息地破碎化不但缩小了栖息地面积。同时也不同程度地降低了栖息地的质量。从而消极地影响着鸟类群落结构的稳定性和鸟类的物种多样性。 相似文献
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The Chaco is the largest dry forest biome in South America and one of the regions most threatened by agricultural intensification. As a consequence, in several areas Chaco forests persist as forest remnants of different sizes embedded in an agricultural matrix. Ants are social insects that have key roles in ecosystem functioning, and the effects of this ongoing land use change process on ant communities are little known for this region. In the present study, we assessed the consequences of land use replacement by monocultures and forest fragmentation on ant communities. Particularly, we assessed whether patch size, patch isolation and edge effect affect species richness and composition of ground‐dwelling ants in fragmented landscapes of Chaco forests. We collected ants by combining hand collecting and pitfall traps in 17 forest fragments and the surrounding matrix from two sites in Córdoba, Argentina. Patch size and patch isolation had no effect on ant richness; however, patch isolation and, to a lesser extent, patch size altered ant species composition. The ant community was not affected by edge but it was negatively affected by the crop matrix, which reduced richness and altered species composition. These results indicate that monoculture matrices severely affect ant communities in the Chaco forests, and that the effects of other indicators of habitat fragmentation (patch size and edge effect) are subtler and less relevant. In the present context of land use change, even small fragments could have an important value for the conservation of ant diversity. 相似文献
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为深入阐明区域红树林空间演变机理,需对红树林斑块数量和面积在不同因子驱动下通过不同途径发生的变化量进行准确计量。提出了在GIS平台支持下的通过空间叠置分析方法进行斑块数量和面积变化量计量的两种方法——精确计量法和整体计量法。首先将前后两期通过遥感图像提取的红树林斑块分布图、遥感图像进行叠合,采用视觉信息叠合方法,将全部斑块划分为众多具有相同主要驱动因子和变化途径的分析单元;若前后期遥感图像能够精确配准,采用精确计量法计量:通过线与多边形叠置方法,用前期斑块的线状图对后斑块的面状图、后期斑块的线状图对前斑块的面状图分别进行切割,每个分析单元得到多个亚斑块,逐一确定每个亚斑块的驱动因子、变化途径,据此统计每个分析单元中斑块数量和面积在不同因子驱动下通过不同途径发生的变化量;若前后期遥感图像难以精确配准,采用整体计量法计量:对于每个分析单元,根据斑块恢复的难易程度、面积和斑块数量变化量的大小,确定其主要驱动因子和主要变化途径,该分析单元前、后期斑块数量和面积之差即为其在监测期间由该因子驱动通过该途径发生的斑块数量和面积变化量。尽管整体计量法对红树林空间演变机制分析的结果与精确计量法存在一定差异,但也属于定量分析范畴,都能深刻阐明红树林空间演变机制,能够全面、准确地反映了区域红树林斑块数量和面积在监测期内增加、减少的动态过程。 相似文献