完全封育方式对天然油松林的影响

Assessment on effect of fully hillsides-closed and afforested mode on natural Pinus tabulaeformis forest

基于敏感性分析,选择了12个反映封育天然油松林植被和土壤特征的指标,建立了封山育林措施实施效果的评价指标体系。根据等间距法,将封山育林措施实施效果综合指数划分为5个等级。采用层次分析法和综合指数法,对封山育林措施在不同封育年限天然次生油松林中的实施效果进行了评价,结果表明封育16,25,30,45,60a和75a的天然次生油松林,封育措施实施效果综合指数值分别为7.25,6.88,7.82,5.51,4.78和2.79,随着封育年限增加,完全封育方式实施效果逐渐变差,本区天然林完全封育年限最长不应超过45a。封育45a后,应采取适宜树种混交、择伐等培育和经营措施。

Huanglong Mountain forest zone is one of the main natural secondary forest zones on the southern Loess Plateau in Shaanxi province. Since 1950, a mode of fully hillsides-closed and afforested （FHA） has been applied in the forest. In some special sites, the forest age even exceeds 80 years. Pinus tabulaeformis forest ks the most important vegetation in warm temperate region in China. Similarly, population of P. tabulaeformis is dominant in the formed forest ecosystem. Quercus Liaotungensis, Syringa oblate, Populus davidiana, Prunus davidiana,, Betula platyphylla and Toxicodendron vernicifluum can be occasionally found in arbor layer and species of shrub are abundant. Based on the data collected from 31 plots and 93 soil samples, health of the forest ecosystem has been discussed and appropriate FHA age has been pointed out. 12 indexes manifesting traits of vegetation and soil in natural secondary P. tabulaeformis forest ecosystem were acquired by sensitive analysis and the assessment index system for FHA mode was established. According to equal distance method, 5 grades of integrated index for evaluating FHA mode were compartmentalized. Effect of FHA mode on natural secondary P. tabulaeformis forest was evaluated by methods of integrated index and analytic hierarchy process （AHP）. The results are follows ： values of integrated index in FHA 16, 25, 30, 45, 60a and 75a were 7.25,6.88,7.82,5.51,4.78 and 2.79 respectively. With the FHA age increase, the effect of FHA mode became worse. It could be concluded that natural forest should not be protected in FHA way more than 45a. After 45a, mixing suitable tree species, select cutting and other cultivating and managing measures should be adopted.