Adapting Characteristics And Seedling Growth Of Quercus Wutaishanica Across Environmental Gradients

Quercus wutaishanica forest is one of the typical zonal vegetation types in warm-temperate deciduous broad-leaved forest and subtropical evergreen and deciduous broadleaved mixed forest. The concentrated distribution zone of Q. wutaishanica in ShaanXi Province is in the south of the Loess Plateau and the north slope of QinLing Moutains, which are the transitional zone between core region and marginal region. The paper mainly took Q. wutaishanica natural secondary forests as research object. Sample-plot survey, localization observation and statistical analysis were used to study the variation characteristics of community, adapting characteristics of population and seedling growing status of different origin across environmental gradients of TaiBai Moutain, HuangLong Moutain and QinLing Moutain so as to provide a scientific basis for the restoration and sustainable management for Q. wutaishanica natural secondary forest. The main results are as follows:1. The variation characteristics of Q. wutaishanica community show that the indexes of height, diameter at breast height, crown width, soil moisture and nutrient across environmental gradients were: TaiBai Mout.>HuangLong Mout.>Yan'an. There existed some differences among species composition of Q. wutaishanica community in the three areas while shrub-grass undergrowth were more prosperous and composite structure formed with tree, shrub and grass to keep soil and water conversation.2. The adapting characteristics of Q. wutaishanica community show that the diameter classes, height classes and growth status across climatic gradients were: TaiBai>HuangLong>Yan'an. From the classes of diameter and height, we can get that there were stable structure of Q. wutaishanica population in the three areas.3. Seedlings age structure of Q. wutaishanica in different areas show that 1-2 years seedling density was HuangLong, Yan'an>TaiBai while that was TaiBai>HuangLong>Yan'an of 4-5 years. Seedling growth status and dry matter quantity distribution of Q. wutaishanica were different among the three areas, individual height, basal diameter and other indexes of aboveground parts were TaiBai>HuangLong>Yan'an, while the some root system indexes of underground parts were HuangLong>Yan'an>TaiBai. The seedling density of Q. wutaishanica of different habitats in HuangLong was: large forest gap>small forest gap>forest vacant land. Forest gap took a positive part in reducing the ecesis process of seedling. Mean height, basal diameter and other indexes of seedling in large forest gap were higher than that in small forest gap and undergrowth. The individual growing status and development of seedlings in large forest gap were better than that in other habitats, which promote it into a natural regeneration forest.4. Sprouts age structure of Q. wutaishanica in different areas show that the sprouts density was HuangLong>Yan'an>TaiBai. The individual height, basal diameter and other sprouts growth indexes of aboveground were HuangLong>Yan'an>TaiBai. The sprouts density of Q. wutaishanica of different habitats in HuangLong was: forest vacant land>large forest gap>small forest gap> undergrowth. The sprouts amounts of forest vacant land and forest gap were obviously higher than that of undergrowth, and thinning had a positive role in increasing the amounts of sprouts. Mean individual height, basal diameter and other indexes in forest vacant land were obviously higher than that in large forest gap and small forest gap.5. Tending thinning should be timely used in Q. wutaishanica natural secondary forest and open forest gap to promote seed setting and sprouts growing so as to increase the forest land coverage. Keeping timber forest and water conservation forest are the main purpose of Q. wutaishanica forest in the north slope of QinLing Mout., ungraded and diseased woods should be thinned to promote the sprouts development and larger diameter woods should be mainly cultivated. Keeping soil and water conversation forest is the main purpose of Q. wutaishanica forest in Loess Plateau, seedling should be mainly cultivated and stump sprouts should be used to recover the forest land rapidly. Low density-high diameter wood should be cultivated in a stable canopy density.