Resources Dynamics And Restoration Strategy Of Natural Forests In Southwest China

The natural forests (NFs) play a more important role in ecological service, such as biodiversity conservation, pest control, water and soil conservation, than the planted forests. But natural forests degradation drove its ecological function down. Natural forests degradation is one of the hard challenges for sustainable forestry development. Southwest China is not only one of two main natural forests distribution areas, but also a severe degradation region of natural forests. The only way fighting the natural forests degradation is to implement research and practice of ecological restoration. This thesis presented the resources dynamics of natural forests in recent 60 years in SW China, and explored the relationship between forests resources consumption and areal economic growth. Based on zoning of natural forests and categories of degradation, it established a set of index system for ecological restoration.The NFs resource is an important indicator for characterizing local ecological environment status. Dynamics analysis of NFs resources is beneficial to improve management efficiency and promote local sustainable development. The 2nd chapter analyzed the NFs data extracted from forests inventory reports published by government since 1949. The results showed that the development of NFs could be divided two phases over the past 60a: wood consumption and ecological restoration. In the first 30a, the NFs area and volume declined by 26% and by 33% respectively because of harvesting timber, whereas they continually recovered under ecological environment construction in the later 30a. The NFs area reached at the top point of 25.87 million ha in 2008 and its stands volume of 3.2 billion m~3, especially with the remarkable promotion of Natural Forest Protection Program (NFPP) since 1999. But the whole quality of NFs increased slowly and 123 m~3/ha was still at the low level in 2008. And the age structure of NFs was unbalanced. Forests volume of young and middle NFs was not increased rapidly with its area, its area percent was 58%, but its volume percent was only 30%. At present the ratio of commercial forests area to ecological ones was almost 7:3 resulted from the increase of shelter forests and decrease of timber forests since 1980s. Commercial timber consumption affected the forests resources dynamics. And the relationship between forests resources consumption and areal economic growth was complex. This paper defined the term of Gold Purchased by GDP (GPG) and regarded it as a new indicator of economic growth. GPG means the gold weight purchased by GDP according to the annual average exchange price and the annual international gold price. Exploring the relationship between natural resource consumption and economic growth will contribute to improve the efficiency of resource utilization. The 3rd chapter analyzed the data of commercial timber harvested, population, GDP and GPG of Southwest China since 1949, tested the hypothesis of resource curse and Kuznets curve. With the GDP increased by 422 times from 1952 to 2008, the population, GPG and commercial timber harvested grew by one times, 4.5 times and 12 times respectively. The timber decreased by 80% resulted from the implementation of Natural Forests Protected Program from 1997 to 2000, but the figure of 9.5 million cubic metres in 2008 reached the level of 1997 and its increasing trend has not been changed since 1949. The linear correlation between GPG and timber consumption in the first 20a was significant. The per capita GPG increased by 1.5 times with the per capita GDP growing of 162 times. The resource curse and Kuznets curve did not exist between timber consumption and per capita GDP or per capita GPG. The commercial timber consumption per 10 thousand Yuan or per kilogram GPG appeared inversed U curve. The economic growth of SW China went through the period which promoted by intensive labor and timber consumption.Forests zoning is one key part of sustaibable forests management. In terms of zonal climax forest types, land features and drivers of degradation, the 4th chapter divided the natural forests in mountains of Southwest China into five zones, namely tropical rain and monsoon forests of low-mountain in South Yunnan, evergreen broad-leaf forests over limestone in Guizhou-Yunnan, evergreen broad-leaf forests of plateau in Central Yunnan, evergreen broad-leaf forests of low-mountain around Sichuan Basin, dark coniferous forests over valley and mountains in Sichuan-Yunnan. Zoning of the natural forests at regional level will add more understandings for the ecological restoration in mountains of Southwest China. Ecological restoration management means forests ecosystem management for the ecological restoration of degraded natural forests. Categories of the degraded natural forests, including severe degradation, medium degradation, slight degradation, and non-degradation,were defined in terms of canopy density, stands basal area, percentage of woodland occupied by invasive plants. Taking consideration of forests health, species diversity conservation, productions recover and soil conservation, the 5th chapter set up some index to guide the ecological restoration of degraded natural forests. These indicators included canopy density, forests area undisturbed by severe human actions or natural disasters, forests area undisturbed by invasive plants, stands DBH basal area, non-timber products, and soil erosion control area.