Study On The Diversity Of Forest Plants And Related Factors In The Eastern Part Of Northeast Forest Region

Study on the diversity of forest plants and its related factors in eastern part of northeast of ChinaCombining community ecology with forest biodiversity preservation, applying both theory and method in modern forestry and ecology, the influences of small-scale disturbance on forest plant diversity were studied on a trial. The forest biodiversity in eastern mountain area of northeast of China and its maintaining mechanism were explained. Development and mechanism of species diversity within community were discussed as well. The conclusions were as following and a new hypothesis was put forwarded in the thesis.1. By calculating and analyzing indictors of plant diversity within community data from three time successive observations on 3-year filed trial and exchanging between time and space, it was proved that habitat physical heterogeneity by small-scale disturbance can increase plant diversity. This was due to that varieties of microhabitats effective to plant germination were much complicated in heterogeneous environment than in homogeneous environment which had single niche, obvious dominant species and intensive competition exclusion and lower diversity; And there was a positive relationship between the forest plant species diversity and nutrient elements content in soil. Matrix quality was a key factor to plant diversity within community; The effect of heterogeneity of small-scale disturbance on species diversity in the next year declined. In other words, the increase of resource efficiency by the disturbance was of temporary or transition. As the plants grow the influence of heterogeneity of disturbance on diversity was smaller and smaller quickly, all of them reflected in richness degree, even degree and biodiversity index had a similar developing trends that were mainly affected by matrix quality, or, resource amount2. Among virgin forest, over-cut forest, and secondary forest, it was proved that plant diversity in different layer (stand crown, shrub and grass ) in varieties of communities depended on degree of disturbance. Because of different disturbance degree the richness degree of community, even degree, Shannon index and even-dominant- richness index showed difference largely as well.3. Development model of plant diversity in whole stage in forest community succession was simulated and improved. Simultaneously described the process of forest plant diversity within the whole stage of succession the causes were explained. Proper disturbance in dad leaves layer can prompt plant germination and give a rise to diversity index during their early growth efficiently.4. By spatial analysis on the pattern of plant diversity in crown , shrub, and grass layer in different forest types the factors to influence plant diversity were determined separately. The distributions of spatial pattern of plant diversity around 'dominant-tree' were described in point pattern analysis method. It showed by the statistics hypothesis test that the relation betweendiversity of grass plant samples and its distance to dominant tree was random following passion distribution. There were a negative relation between diversity and plant cover in grass samples.5. Based on preceding researches by other researchers, a new hypothesis of resource amount and degree of disturbance about key factors to maintain species diversity within community was developed that the key factors included niche amount and region diversity provided by community and seed source situation neighboring community.