Research On The Structural Haracteristicsand Ecological Functions Of Three Types Forest In North Mountain Of Hebei Province

In this paper, the main forest community structure and ecological function of three kinds of typical forest (Larix principic-rupprechtii-B.platyphylla-B.davurica、Populus davidian- B.platyphylla-B.davurica and Pinus tabuliformis -Quercus mongolica) were studied in north mountain of Hebei province, which included some key regional issues such as unreasonable shelterbelts structure、ecological degradation, so that it could provide reference of ecological forest construction and the sustainable development of forest management in north mountain of Hebei province.There are 56 kinds of plants in standards of Larix principic-rupprechtii-B.platyphylla-B.davurica, 53 kinds of plants in standards of Populus davidian- B.platyphylla-B.davurica, and 54 kinds of plants in standards of Pinus tabuliformis -Quercus mongolica. Larix principic-rupprechtii-B.platyphylla-B.davurica is needle into the broad-leaved forest which based on natural secondary forest, so the dominance of ten larch is obvious. The dominant species in shrub layer wool are hazel and cornus alba. Herb layer have many types, but the dominant position is not very prominent, the dominance species in herb layer are Phlomis umbrosa, Yama Mako and lanceolate carex. In Pobulus davidiana and Populus davidian- B.platyphylla-B.davurica the dominance species are aspen and birch. The dominance of wool hazel compared with other species is very obvious in shrub layer, and the dominance species in herb layer are brown and cohosh. The dominance tree species in Pinus tabuliformis -Quercus mongolica are Pinus tabuliformis and Quercus mongolica, the dominance species in shrub are Lespedeza bicolor and Spiraea.salicifolia, and the dominance species in herb layer including Ciraea.alpina,Carex.lanceolata and Dendranthema.chanetii.Total storage capacity of forest composed of that water holding capacity of the part on the ground and soil layer. The greater of the forest total storage capacity, the stronger of the forest water conservation capacity. In the comprehensive comparison, we can see that the main place of forest water conservation is the maximum water holding capacity of soil. In the comparison of three forest types, Pobulus davidiana and Populus davidian- B.platyphylla-B.davurica(2289.79 t/hm2)> Larix principic-rupprechtii-B.platyphylla-B.davurica(1987.05 t/hm2)> Pinus tabuliformis -Quercus mongolica(1855.05 t/hm2). The visual factor that effects the biological diversity index of tree layer is types of community. Different community have large difference in species richness, diversity index and evenness. The whole community is more evenly distributed, the Menhinick richness index of community is relatively low, the Shannon-Weiner index of Pinus tabuliformis -Quercus mongolica is greater than Populus davidian- B.platyphylla-B.davurica; about species diversity index of shrub layer that Pinus tabuliformis -Quercus mongolica > Populus davidian- B.platyphylla-B.davurica > Larix principic-rupprechtii-B.platyphylla-B.davurica; herb diversity index in the same forest the bottom of the slope >the middle of the slope >the tope of the slope, and in three forest types Pinus tabuliformis -Quercus mongolica > Populus davidian- B.platyphylla-B.davurica > Larix principic-rupprechtii-B.platyphylla-B.davurica. The index change tends to be consistent between tree、shrub and herb. The change of nutrients content in soil have no obvious regularity, but the experimentally determined values on the whole level is generally lower than soil standard in North China.Through the standard survey data to the three stands, from eight indicators of the structural, functional and adaptive three aspects, use Analytic Hierarchy Process to determine the index weigh, then combination to complex structure and function indicators make assessment to the three stands. The results of the assessment is Larix principic-rupprechtii-B.platyphylla-B.davurica at sub-health level, the mixed forest of Populus and Betula and the mixed forest of Pinus and Mongolicain at health level.The dominance of larch is obvious in the structure of Larix principic-rupprechtii-B.platyphylla-B.davurica, but there is no seedlings and soil needs management by human because it’s low nutrient content. The dominance of Populus davidian- B.platyphylla-B.davurica and Pinus tabuliformis -Quercus mongolica, and it have the largest species diversity index compared with the other two forest types. It considered to be top structure of forest community in North Mountain of Hebei Province. We can see from diameter spectrum, pinus being in the growth state in tree diameter. It have benefit to increase forest reserves and seedlings. The good management of this kind of forest can provide a basis for other forest types.