Research On Hydrological And Ecological Functions Of Typical Forest Types In Napahai, Yunnan

Lake Napahai is a typical plateau wetland in Yunnan. Thank to its unique eco-function and landscape, Lake Napahai catches much attention. The natural plants community has rich diversity, which plays an important role for water conservation, soil conservation and maintaining of eco-balance. However, recent years, due to the disturbance of human activities, the Napahai Wetland began to show the sign of degradation of ecosystem. There are many traits, such as shrinking of wetland coverage, sucession of marsh vegetation, degradation of soil quality. This paper is mainly about research on hydrological and ecological function of the forest ecosystem in this drainage, so that a comprehensive evaluation of the surface runoff-reduction, flood peak-control, water and soil conservation. This could provide theoretical support to maintainance and management on the water and soil conservation forest.According to principle of water balance, using the re-allocation method of rainfall, monitoring and study were carried out on the hydrological and ecological function of typical landuse type in this drainage:alpine pine secondary forest, Sichuan-Yunnan oak shrub, birch forest, waste grassland, slope farmland. Hydrological data was collected different parts of different types of forests, canopy, litter layer and soil layer. Statistics, regressive analysis, correlative analysis, and grey correlation analysis were applied for comparative analysis. Comprehensive evaluation was analyzed on hydrological and ecological function of different forests. Hereafter are the results:1) The retention rate of different typical forests are alpine pine secondary forest (28.75%)> birch forest (20.28)> Sichuan-Yunnan oak shrub (15.75%)> artificial young picea asperata forest (11.48). Judged by the retention rate, the retention capacity of canopy is related to the structure characteristic, rainfall and the maximum capacity. The retention rate of all the four types of forest decrease as the rainfall increases.2) The maximum water capacity and effective retaining content of the litter layer for each type of forest is proportional to the capacity:alpine pine secondary forest> birch forest> Sichuan-Yunnan oak shrub. Forest with rich litter layer has also strong water capacity. The water capacity increase sharply at the early soaking stage. Water capacity reaches a relative high level after 2 hours of soaking, then gets relatively stable.3) The effective retaining content of high mountain oak shrub soil is obviously higher than other forest types,2.65 times of that for waste grassland, and 2.36 times of slope farmland. The effective retaining content of layer 0-30cm is much higher than that of 30-50 cm. The water capacity for different forest types, Sichuan-Yunnan oak shrub> alpine forest> birch forest> artificial young picea asperata forest> slope farmland> waste grassland.4) According to the monitoring data, in 2003 and 2006, the number of times and runoff depth is the highest for waste grassland, then slope farmland. The alpine forest has the lowest runoff. In 2009, the runoff depth, slope farmland> artificial young forest> waste grassland> alpine oak shrub> birch forest> alpine pine secondary forest (65.88mm>42.16mm>25.02mm>20.5 mm> 15.76 mm> 13.56 mm). The runoff decrease year by year for these forest types except slope farmland shows the trend of increasing.5) Alpine pine secondary forest, Sichuan-Yunnan oak shrub and birch forest show good function of water conservation and reduction of soil erosion. The function of artificial forest increases yearly. Waste grassland and slope farmland will make a lot of surface runoff and mud in rain season. Hence, rational pasture and grassland management, protection of natural forest, and returning farmland into forest would be long-lasting work for Lake Napahai to decrease lake deposition, increase water level especially in dry season, and stop degradation of eco-function.Many people have done a lot of fundamental research on soil degradation, layout change of landscape, botany diversity and functional zoning of nature reserve. This research is based on the previous studies and has some inovation. This research follows the principle of water balance, does analysis on rainfall re-allocation, and reveals the differences of hydrological and ecological function of the forest ecosystem in this drainage. This research has provides more appropirate method for culturing of water and soil conservation forest, which also add more theoretical support for eco-reparing of Lake Napahai.