Study On Natural Superior Stands Selection Criteria And Method Of Mainly Broadleaved Tree Species In Beijing

Forest tree germplasm is the material basis of ecological construction, which is one of the most important but non-renewable strategic resources to human beings. Beijing has plentiful forest tree germplasm, especially rich in indigenous broadleaf species, which play an important role in stability forest community structure in Beijing. The afforestation survival rate can be increased obviously by using indigenous tree species, especially superior indigenous tree species as the seedling source for plantation and lay a good foundation for later stand quality improvement. This thesis chooses the tree species which mentioned above as study object, the selection criteria and method has been proposed base on survey and analysis of forest stands of Quercus mongolica, Juglans mandshurica, and Betula platyphylla, finally superior stands has been selected.There are mainly research results:(1).The forest community characteristics of Quercus mongolica forest, Juglans mandshurica forest, Betula platyphylla forest had been identified;(2).The forest site quality had been evaluated by using grey correlation analysis, quantification theory 1 and system clustering method. And the dominant factors of each forest's growth had been determined, to Quercus mongolica forest which are slope, aspect, elevation, and classified 36 site types, 3 site grades; to Juglans mandshurica forest which are slope position, thickness of humus and elevation, and classified 18 site types,3 site grades; to Betula platyphylla forest which are aspect, elevation and thickness of humus and classified 36 site types,2 site grades.(3). The selection criteria for identifying superior stands by using comprehensive growth-index and quality-index evaluation method had been established, which can be used easily and quickly to identify the superior stands. (4). With the selection criteria which mentioned above, the distributions and quantities of superior stands of Quercus mongolica, Juglans mandshurica, Betula platyphylla in Beijing had been distinguished. The quantities of the three superior stands are 9,3,5respectively.