Ecological Effects Of Human Disturbance On Plant Diversity Distribution In Dongling Mountain, Beijing

During last years in Beijing regions, human disturbance, especially agricultural cultivation and economical tourism, resulted in obvious changes of landscape structure characteristics and plant diversity. Precious researches mostly focused on analyses of landscape structure and plant diversity under natural environments, had a few attentions on effects of human disturbance on both sides. In the paper, TM data of Dongling Mountainous region in 1984,1994,2002 year were used, in order to analyze effects of human disturbance on whole landscape structure and pattern in 20 years. Moreover, TM data in 2002 year were processed in ARCGIS, and buffers of different distances were constructed surrounding villages and roads. Then, both buffering analyses in landscape scale and plant diversity studies in community scale were linked, in order to further study effects of human disturbance on partial landscape characteristics and plant diversity, to find out inherent effects and disturbance mechanism of human disturbance on them, to provide theoretical bases for reasonable land utilizations,tourism explosions and biological diversity protections.(1) Both human disturbance and natural environment (e.g. the altitude) commonly resulted in the whole landscape characteristics and partial landscape differences. The altitude constructed the whole landscape characteristics in the region, and human disturbance had bigger influences on areas surrounding villages and roads, leaded to changes of partial landscape, and increased the partial fragmentations and diversity. Different distances apart from villages (including 250m, 500m, 750m) and roads (200m, 400m) reflected a gradient of human disturbance. With increasing disturbance distances, every landscape types majored in larger patches, represented a merging trend, and landscape fragmentations, diversity and edge complication all descended.(2) results of cluster analyses showed that plant communities surrounding villages and roads could be classified in 4 land uses (including farmland, fallow land, shrub and forest), and these proved of research methods again. Under human disturbance, the farmland and shrub replaced the forest, and the order of the disturbance intensity was village>farmland>shrub>forest and grass. Therefore, human disturbance changes plant diversity and distribution surrounding villages and roads, especially herb species.(3) in the study of plant diversity surrounding villages, PCA and CCA were used to analyze the correlation between 13 environmental factors and 134 plant species, result showed both soil and topographic factors were main influence factors. The altitude had larger influences on plant diversity; soil factors were secondly, e.g. SOM, pH and SW etc. in the study of plant diversity surrounding roads, PCA and CCA were also used to analyze the correlation between 10 environmental factors and 42 plant species, results also showed that soil and topographic factors were main influence factors. So, the altitude decided changes of plant diversity, however, human disturbance might cover these effects of the altitude. Both the altitude and human disturbance commonly decided plant diversity and distribution, and were coupling gradients effecting plant pattern.(4) different intensities and ways of human disturbance resulted in different land uses, and further shaped different ecotone. However, the ecotones had different effects on plant diversity, might increase, decreased or never alter plant diversity. Similar analyses of plant community helped to study plant diversity, in order to research differences of plant communities and diversity in different land uses.(5) changes of plant diversity surrounding villages and roads were similar, and were coupling effecting results of human disturbance and the altitude. Otherwise, secondary rank roads had larger effects on plant diversity than first rank roads, and because secondary rank roads were useful to human agricultural cultivation and economical tourism. Linear net distribution of roads expanded ranges of human activities, and enhanced effects of human disturbance on local landscape structure, pattern and plant diversity. Villages and roads commonly comprised networks of human activities, and had coupling effects on landscape pattern and plant diversity.(6) between plant diversity and human disturbance, as well as environmental changes were closely correlated. Studies of Plant diversity surrounding villages showed that plant diversity of shrub reached a bottom, which of forest reached a peak. Shrub was under middle human disturbance, and farmland and fallow land were under strong human disturbance. Plant diversity never reached a peak, and reached a bottom under middle disturbance. This phenomenon was not consistent with IDH (the hypothesis of intermediate disturbance), because of different study objects, and also reflected the altitude and human disturbance commonly decided changes of plant diversity.(7) in both landscape and community scales, in virtue of ARCGIS and FRAGSTATS software, combining remote technology and traditional field investigation, effects of human disturbance on landscape and plant diversity were studied by several landscape indexes, and correlation of human activities and plant diversity were also discussed, and effects and disturbance mechanism of human disturbance were also found out.