【摘 要】
：
Plant diversity is used as an indicator of the well-being of vegetation and ecological systems. Human activities and global change drive vegetation change in co
【机 构】
：
WSL,Swiss Federal Institute for Forest,Snow and Landscape Research,Zürcherstrasse 111,CH-8903 Birmen
论文部分内容阅读
Plant diversity is used as an indicator of the well-being of vegetation and ecological systems. Human activities and global change drive vegetation change in composition and competition of species through plant invasions and replacement of existing species on a given scale. However,species diversity indices do not consider the effects of invasions on the diversity value and on the functions of ecosystems. On the other hand, the existing methods for diversity index can not be used directly for cross-scale evaluation of vegetation data. Therefore, we proposed a 3-dimensional model derived from the logistic equation for estimating vegetation change, using native and non-native plant diversity. The two variables, based on the current and the theoretical maximum diversity of native plants on a given scale, and the result of the model are relative values without units, and are therefore scale-independent. Hence, this method developed can be used directly for cross-scale evaluations of vegetation data, and indirectly for estimating ecosystem or environmental change.
其他文献
19世纪新古典主义的诞生，代表着绘画艺术迈出了由“神”向“人”转变的第一步，随后的现实主义则继承了新古典主义的衣钵，并且使得绘画艺术完成了由“神”到“人”的整个转变。它
小学课本里，我们学过一篇文章叫做《金色的鱼钩》，记述了这样一个真实故事：红军在长征途中，有位炊事班长照顾三个生病的小战士过草地，一路上想尽办法钓鱼煮野菜汤，给他们充饥养病，自己却一口也舍不得吃，最终在饥饿与寒冷中日渐消瘦，直至壮烈牺牲。现在，那枚长满红锈的珍贵鱼钩就珍藏在中国人民革命军事博物馆，也许它是见证长征最渺小的物件，但从艰苦卓绝的战争年代走来，它凝结了红军将士团结友爱、舍己为人的伟大长征精
艺术创作是我们对客观生活的主观认识和能动创造，是主客体的遇合和主客观的统一。只有积累了大量的生活素材，我们才能从中生发出独特的感受激发出强烈的感情，提炼出深刻的思想，创
电教媒体作为现代教育技术,可以提供形象、直观、生动的视觉画面和听觉刺激,对于激发学生的学习兴趣,丰富学生的感性认识有着十分重要的作用。但反观我们现在的小学语文课堂,
江苏省大港中学英语教师潘晓宇是一名军嫂,她的丈夫徐璟是武警镇江边防检查站政治处主任.他们结婚7年来,一个爱岗敬业,一个爱军精武,互敬互爱,相互支持,相互勉励,在各自的岗
Due to complex terrain of the Loess Plateau, the classification accuracy is unsatisfactory when a single supervised classification is used in the remote sensing
Slope is one of the crucial terrain variables in spatial analysis and land use planning,especially in the Loess Plateau area of China which is suffering from se
Evapotranspiration (ET) is an important parameter for water resource management.Compared to the traditional ET computation and measurement methods, the ET compu
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grass