【作者】 徐国策；

【导师】 赵鹏祥；

【作者基本信息】 西北农林科技大学 ， 森林经理学， 2009， 硕士

【摘要】 在植被恢复过程中进行立地类型划分,是必要的基础性的工作。为了更好地在陕北农牧交错带进行植被恢复,做到适地适树,必须进行立地类型划分,摸清该区域的各种立地类型面积及其分布特点,划分出植被重建的难易程度,从而实现对造林地进行科学规划。到目前为止,在GIS技术支持下,对陕北黄土高原农牧交错带的立地类型划分研究尚未见报道。本研究在对陕北农牧交错带6个县区(吴起、志丹、靖边、横山、榆阳、神木)植被生物量调查的基础上,主要以陕北吴起县农牧交错带的周湾镇和长城乡为例,运用数量化理论Ⅰ、GIS空间分析技术,以土壤含水量为主导因子对该区域的造林立地类型进行了划分,获得了立地类型分布图,并对各造林立地类型的数量和分布进行了分析,同时,编制了各立地类型的适生树种表,提出了造林技术模式。本次研究的主要结论有:(1)陕北农牧交错带植被具有很强的次生性,从东南向西北由森林草原向干旱草原、荒漠草原过渡,土壤主要为黄土和风沙土。乔木树种有河北杨、小叶杨、刺槐、油松、旱柳、杜梨、山杏、榆、桑、梨、苹果、侧柏、核桃、枣等。灌木有沙棘、柠条、紫穗槐、柽柳、沙柳、山桃、文冠果等。生物量主要受水分影响,随着立地条件的变坏而减小。(2)研究区内水分是制约造林成活的主要因素,依据土壤含水量将立地等级划分为5类,即优、良、中、及格和差。数量化理论Ⅰ表明影响土壤水分的因子按大小依次为坡向、坡位和坡度,将土壤含水量用更直观的地形因子表达,立地类型可划分为18类,分别对应于不同的立地等级。(3)吴起县东北部优类立地类型面积为113.47hm2,占总面积的27.92%。这一部分地类上植被易恢复,主要集中在沟底和阴向坡度较缓的土地,土地质量较好,是发展经济林、农田防护林和用材林的主要用地,适生树种有小叶杨、柳树、苹果、榆树等。良类立地类型面积为99.06hm2,占总面积的24.37%,植被可恢复,这部分地类主要在坡的下部,是水土保持林和部分薪炭林的用地,主要适生树种有侧柏、榆树、油松、刺槐等;中类立地类型面积为109.15hm2,占总面积的26.86%,植被较难恢复,可以种植侧柏、刺槐等耐旱树种;及格类立地类型面积为84.76hm2,占总面积的20.85%,水分限制较严重,在目前的技术条件下,对梁、峁、顶建议种植耐旱的沙棘和柠条。(4)本研究中,采用的以土壤含水量为主要指标、以数量化理论Ⅰ为造林立地类型定量划分的理论基础、以DEM为地形因子自动提取以及森林资源二类调查结果为依据的适地适树决策的技术流程,为进一步实现立地类型自动划分和适地适树决策支持系统奠定了基础。更多还原

【Abstract】 Site type classification is the necessary and basic work in the process of vegetation restoration. For better restoring vegetation and planting trees on the suitable sites condition in Agriculture and Pasturage Interlaced Zone of Northern Shaanxi, Site type classification must be carried out, each site type area and distribution characteristics must be understood and difficulty degree of reforestation must be divided, thus realizing the scientific planning for reforestation. So far, site type classification in Agriculture and Pasturage Interlaced Zone of Northern Shaanxi based on GIS has not been reported. The study adopts the quantification theoryⅠcombining with the GIS technology, taking Zhouwan town and Changcheng town of Wuqi County in northern Shaanxi for example, based on investigating vegetation biomass in six counties(Wuqi, Zhidan, Jingbian, Hengshan, Yuyang, Shenmu)of Agriculture and Pasturage Interlaced Zone of Northern Shaanxi, carries on the site type classification taking water content as the main factor, obtains the site type distribution map and analyzes the area and distribution of each site type, at the same time, establishes the suitable tree species for each site type and puts afforestation technology model forward. The main conclusions of the study are as follows:(1) Vegetation shows strongly man-made characteristic in Agriculture and Pasturage Interlaced Zone of Northern Shaanxi. From the southeast to the northwest, vegetation shows a transition from forest-grassland to arid grassland, desert grassland. Soil is mainly loess and Aeolian sandy soil. The arbor species are mainly Populus hopeiensis, Populus simonii, Robinia pseudoacacia, Pinus tabulaeformis, Salix matsudana, Pyrus betulaefolia, Prunes armeniaca, Ulmus pumila, Morus alba, Pyrus pyrifolia, Malus prunifolia, Thuja orientalis, Juglans regia, Zizyphus jujube, etc. The shrub species are mainly Hippophae rhamnoides, Caragana microphylla, Amorpha fruticosa, Tamarix chinensis, Salix psammophila, Prunus davidiana, Xanthoceras sorbifolia, etc. The biomass is mainly affected by water, reducing as the site condition deteriorates.(2) The water content is the predominant factor in restricting the survival rate in the study area. According to the water content, the site types are divided into five ranks: superior, good, medium, passing, bad. The quantification theoryⅠindicates that the factor affecting the soil water is: the aspect>the slope position>the slope. The water content can be intuitively shown by the terrain factors. The site types are classified into 18 kinds, corresponding to different site type ranks.(3) According to the statistical result, the superior site type area is 113.47 hm2 in the northeast of Wuqi County, accounting for 27.92% of the total area. The part is easy to restore vegetations, mainly concentrating in the bottom and the shade-gentle area, which has good quality and suits to develop economic forest, farmland protection forest and timber forest. The suitable trees are Populus Simonii,Salix matsudana,Malus prunifolia,Ulmus pumila, etc. The good site type area is 99.06 hm2, accounting for 24.37% of the total area. The part can be restored, mainly concentrating in the downhill, which is suitable to develop water conservation forest and fuelwood forest. The suitable trees are Thuja orientalis,Ulmus pumila,Pinus tabulaeformis,Robinia pseudoacacia, etc. The medium site type area is 109.15 hm2, accounting for 26.86% of the total area. The part is difficult to restore vegetations where can be planted Pinus tabulaeformis,Robinia pseudoacacia, etc. The passing site type area is 84.76 hm2, accounting for 20.85% of the total area. The part is advised to plant Hippophae rhamnoides and Caragana microphylla for lacking water heavily.(4) The technology flow of planting trees on the suitable sites condition in the study, which takes water content as the main factor, adopts the quantification theoryⅠas theoretical basis of site type quantitative segmentation and takes site factors auto-computation based on DEM and forest resource inventory data as the condition, provides the foundation for site type automated classification and decision support system of planting trees on the suitable sites condition.更多还原