Spatial Para Allocation of a Small Watershed Protection Forest System | 小流域防护林体系的空间对位配置

Chinese. 利用2005年度的IKONOS4卫片（通过解译获得官司河小流域土地利用现状数据）、1：1万森林资源分布图、2007年度森林资源二类调查小班资料,结合样地调查数据以及四川省林业科学研究院森林生态效益定位站（四川绵阳新桥）径流场的有关数据,选取坡度、土层厚、土A层厚、土壤含水率、坡位、土壤类型6个立地特征因子,建立该流域的297个小班物元模型,对其进行适宜性评价,再用层次分析法对其进行优化,从而获得该流域防护林体系空间对位配置。结果表明：1）本区针阔（桤柏/栎柏）混交林面积为124.39hm2,仅占整个有林地面积的14.97%,而针针混交林（松柏）的面积却占27.37%,针叶纯林（马尾松/柏木）的面积更是占42.48%。2）经优化后本区防护林体系分配按面积大小排序为针阔混交林（31.12%）〉灌木林（15.5%）〉经济林（12.28%）〉针针混交林（11.46%）〉阔叶纯林（11.41%）〉针叶纯林（9.51%）〉草地（8.70%）。优化后,年径流总量将减少43171mm,减少62.15%;年土壤侵蚀总量减少465.97t,减少79.66%。3）该流域的防护林体系空间对位配置结果为：①少发展柏木、马尾松纯林,多发展桤柏、栎柏、松栎等针阔混交林。对现有的柏木、马尾松纯林,引进桤木、栎类等树种形成针阔混交林。②柏木纯林和桤柏混交林的郁闭度控制在0.60～0.75,栎柏混交林、松柏混交林、松栎柏混交林则应控制在0.60～0.80。③对现有针叶纯林、针针混交林,采用开窗补阔和密度调节2种方式进行改造。开窗补阔对密度过大的林分进行带状砍伐,砍伐后补植栎类、桤木、香樟、天竺桂等阔叶树种。④在树种的搭配上,根据不同立地条件及树种的适宜性,选择不同的混交比。在中性或微酸性紫色土上,多发展以柏木为主的混交林;在黄壤和酸性紫色土上,则可发展柏木、马尾松与其他阔叶树种的混交林;在灰白砂土上配置以马尾松为主的针阔混交林。阔叶林的比例不少于20%～30%,立地条件好的则可以达到40%左右,以充分发挥防护林的生态效益和增加经济效益。

English. With the interpreted IKONOS4 satellite images collected in 2005,a 1：10 000 forest map,the data collected in Class II forest survey in 2007,and surface runoff data obtained in the permanent runoff monitoring station,six site factors of slope gradient,slope position,soil thickness,soil thickness of A layer,soil type and soil water content were selected to establish a matter element model suitable to 297 forest sub-compartments.Further,the AHP was applied to modify the spatial structure and form the spatial para allocation of the protection forest system.The results showed that：1） the area allocation of different vegetation types was irrational,the area of a mixed coniferous and broad-leafed forest was 124.39 hm2,accounting for 14.97% of the forested land,the mixed forest was consisted of two coniferous species accounted for 27.37% of the total forest land,and the pure forest was consisted of one coniferous species accounted for 42.48%.2） After optimization,the area allocation of different vegetation types in the protection forest system ranked as：the mixed coniferous and broad-leafed forest（31.12%）shrub land（15.5%）the economic tree crops（12.28%）the mixed forest consisting of two coniferous species（11.46%）the pure broad-leafed forest（11.41%）the pure coniferous forest（9.51%）grass land（8.70%）.Besides,the annual surface runoff could reduce 43 171 mm or 62.15%,annual soil erosion could decrease 465.97 t or 79.66%.3） The following suggestions for spatial para allocation of the small watershed protection forest system were proposed：① reducing pure cypress or pine forest,and increasing alder-cypress,oak-cypress or pine-cypress mixed forest.As for the current cypress and pine pure forests,alder or oak could be introduced to develop a mixed forest.② The canopy closure of pure cypress forest and alder-cypress forests should be maintained within 0.60-0.75,and the canopy closure of oak-cypress,pine-cypress or oak-pine forests should be controled within 0.6-0.8.③ For improvement of current pure coniferous forests,an opening and beating-up method and the density regulation could be applied.For the opening and beating-up operation,strip cutting and replanting of broad-leafed species,such as oak,alder and camphor,could be applied.④ For enrichment of species composition,the mixture ratio should be based on the specific site condition and tree features.In the neutral or minor acid purple soil,mixed cypress forest would be favorable;in the yellow and acid purple soil,cypress-broad-leafed or pine-broad-leafed forest would be suitable.In the grey sand soil,pine-broad-leafed forest could be dominated,and the broad-leafed species could reach to 20%-30%,even 40% in favorable sites.