| The farmland protection forest in Jingtai electric-irrigated area plays an important role in improving the ecological condition for farming and ensuring the normality of the people's life in that place. An objective and complete evaluation of the multiple benefits of farmland protection forest and analysis of the producing mechanism of these benefits are very useful for the construction and development of farmland protection forest. In this thesis the multiple benefits of the farmland protection forest in Jingtai electric-irrigated area are evaluated by using the principles and methods of economy, ecology and silvics. The main results are showed as following:1 According to the data investigated in stand sample plot, the prediction model of real stand growth of farmland protection forest in Jingtai electric-irrigated area was established. Then according to the prediction model of real stand growth, the growth process table and the mean money income table of all age classes were obtained and the cutting cycle was defined as 18 year. The value on timber benefit was calculated as 19071068.7 Yuan/a according to the mean money income table of all age class and cutting cycle. Other economic benefits included forestry by-product benefit and fruits benefit of production forest. The value on these benefits are 4027647.4 Yuan/a, 4966950 Yuan/a respectively. The total value on the economic benefits of farmland protection forest in this area is 28065666.1 Yuan/a obtained by adding up the values on the three benefits.2 Agricultural production increased benefit is the most important part of ecological benefits of farmland protection forest in Jingtai electric-irrigated area. The theory of quantification was adopted in the thesis to analyze the influence degree of the factors, including percentage of forest cover, precipitation, damage ratio, improving of crop varieties, fertilizer quantity, farm chemical quantity and agricultural production. The agricultural production increased benefit of farmland protection forest was obtained according to analyzed result. The value on agricultural production increased benefit is 17948564.8 Yuan/a. Other ecological benefits were adding soil fertilizer benefit, oxygen production benefit. The values on these benefits are 9585064.8 Yuan/a, 24351016.3 Yuan/a. The total value on the ecological benefits is 51884645.9 Yuan/a.3 The economic measure results show that the total value on multiple benefits offarmland protection forest in Jingtai electric-irrigated area is 94675404.8 Yuan/a, in which the value on economic benefits is 28065666.1 Yuan/a, the value on ecological benefits is 58190038.9 Yuan/a, the value on social benefits is 8419699.8 Yuan/a.4 Regional ecological benefit of the farmland protection forest in Jingtai electric-irrigated area was studied, adopting the method of gray associate analysis. The gray associate degrees between forest cover percentage and climatic phenomenon factors of region climate including annual average air temperature, annual maxim air temperature, annual minimum air temperature, annual precipitation, annual average wind velocity and freeze-free season are 0.5781, 0.5691, 0.6095, 0.5671, 0.5739, 0.5647, 0.5680 respectively. The results showed that the effects of construction of farmland protection forest in Jingtai electric-irrigated area to the region climate of this area are not significant under the current size of farmland protection forest system.5 Results of compound analysis indicated that the main factors restricting the multiple benefits of farmland protection forest in Jingtai electric-irrigated area include five aspects as follows: the area of farmland protection forest is small; The forest types ratio and tree species structure were not in reason; Pest and disease are serious; The management is too extensive; The construction fund is of shortage; There are some conflicts between the construction of farmland protection forest and the construction of other aspects. Aiming at so... |
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