THE RESEARCH ON VALUATION OF FOREST ECOSYSTEM PRODUCING ORGANIC MATTER IN SHAANXI

The biosphere and land vegetations are the material foundation on which human being live, and which provide us valued resources, such as food, medicinal materials, and original materials. Therefore, the net primary productivity (NPP) is the main character of the ecosystem. Based on extensive and deep research, we can better understand the ecosystem process and ecosystem function. The research of the former was more from the angle of nature ecology and concerned productions of the NPP that measured, less from other merchandise in the market economy frame. This paper is based on the comprehensive survey of forestry ecosystems in Shaanxi Province. The mass of land vegetation in Shaanxi Province was studied with Geographic Information System (GIS) technology, ecological principles and ecological economy principles, utilizing improved NPP modeling, which based on the differences of vegetation types and overlay rates. The results show that land vegetation produces 150.9×106 t biomass in 2.1×108 hm2 area of Shaanxi Province. The district variety of land vegetation in Shaanxi Province is evident, and the difference of productivity for different vegetion types is big. In Shaanxi Province the highest NPP is 12.610 7 t·hm -2·a -1, which lies in Qinba mountain and the type of vegetation is subtropical bamboo grove; For the area along the Great Wall and the wind sand in North of Shaanxi Province, NPP is very low, less than 5 t·hm -2·a -1; With the influence of the industrialization, NPP in Guanzhong basin is low too, less than 7 t·hm -2·a -1. In Shaanxi Province, with the vegetation type and climatic zone, the NPP of unit area has the regular variation, the NPP material mass of subtropical bamboo forest is 12.61 t·hm -2·a -1, coniferous forest 8.1-12.61 t·hm -2·a -1, shrublands 5.6-10.61 t·hm -2·a -1, grasslands 2.4-6.2 t·hm -2·a -1, fruiter 4.4-9.9 t·hm -2·a -1. The distribution pattern of NPP is as follows: the natural forest ≥ artificial fruit trees ≥ grasslands ≥shrublands in terms of vegetation types; Subtropical temperate zone ≥warm temperate zone ≥ temperate zone in terms of climatic zones; Generally speaking the NPP attains the biggest in the elevation 1 000-1 300 m. On the basis of net primary productivity, the paper uses the coal market valuation to evaluate the primary productivity value in this area. The results are that the total value of QinBa Mountains primary productivity adds up to about 358.50×10 10 yuan (RMB)per annum, accounting for 8% of GDP, in which natural forests is 83.21×10 10 RMB; shrublands are 25.51×10 10 RMB; Grasslands are 10.53×10 10 RMB; manual fruiters are 43.40×10 10 RMB. Although, estimation of this NPP value is conceptual and conservative, it can still reveal that the NPP of land vegetations is essential part in the big agriculture. Compared with the value of the agriculture in 2000, the value of NPP occupies 37.05% of the gross agriculture; which is 3.29 times than that of forestry; 1.36 times than that of livestock husbandry; and 7.95 times than that of wood in the same time. This research establishes the foundation of considering net primary productivity of land vegetation, and bringing it into the national economic system.