【作者】 孙尚华；

【导师】 刘建军；

【作者基本信息】 西北农林科技大学 ， 生态学， 2008， 硕士

【摘要】 在对研究区域社会经济和自然环境基本情况进行广泛调查的基础上,以冉家沟流域的1∶10000的地形图、1999年和2007年的土地利用现状图、研究区域的土壤资料以及实地调查的植被资料为基础,制作了研究区的数字高程模型(DEM)和2007年的植被类型图;应用地理信息系统,对研究区域的景观格局、植被分布的地形的分异规律做了较为全面的分析,并在以上的研究基础上对冉家沟村做了景观生态规划与设计,主要取得了以下结论:1)由于1999年退耕还林还草政策和2003年生物措施治理水土流失方案的实施,冉家沟流域1999-2007年耕地面积急剧减少,主要转变为新造林地、人工草地及部分幼林地,在农、林、牧中,林草比例上升。2)选取的7个景观生态学指标揭示了在小流域综合治理的政策下冉家沟流域的景观格局变化规律和特点,流域的土地利用景观格局的总体变化显著,景观多样性指数和优势度指数均有上升,斑块总数明显减少,各景观类型分布趋于集中,景观格局趋于简化。3)冉家沟流域高程变化较小。耕地在低海拔处750-850m占有最大的面积的百分比,其次是刺槐;850-950m区域内中天然林分分布面积较少,以人为活动所形成的土地利用类型占主导;该区的天然灌丛和草地面积所占比例相差不多;在海拔区950-1150m之间的植被类型以天然灌丛、天然草地和林地为主;在海拔1150-1330m,植被类型的种类减少,杨树林只占极少的比例,刺槐在所占面积比例在25%以上,是该区的主要植被类型;以胡枝子、多花木兰为优势种的灌丛分布广泛;以铁杆蒿为优势种的天然草丛在该区域的面积占到15%左右。4)耕地集中在坡度是25°以下的地区;林地中以刺槐林的面积最大,遍及各个坡度,集中在坡度15°-35°地区;天然杨树林、侧柏林面积所占比例不大,但分布广泛,多分布在难利用地区域;胡枝子和以胡枝子为优势种的灌丛,集中分布在＞25°的地区;天然草地是以铁杆蒿为优势种的草本群落,主要分布在坡度大的地区。5)侧柏和刺槐林生长范围最广泛,它们的最大面积都出现在半阴坡和阴坡;天然次生的杨树林则几乎都生长在阴坡和半阴坡地区。天然灌丛的分布较为复杂,胡枝子灌丛最大面积在半阴坡处,与之相反,酸枣灌丛阳坡出现最大面积。以大油芒为优势种的草本群落分布范围是平地到半阴坡,与之相连接的是铁杆蒿群落,分布从半阴坡到阳坡,最大面积出现在半阳坡和阳坡。在平地有分布的是艾蒿-牡蒿群落:耕地在流域的各坡向都有分布,最大耕地面积出现在半阳坡。6)轻度土壤侵蚀地区,耕地占总面积的20%,林地在该地区所占比例只有15%多,灌丛和草地面积比占到总面积的一半以上,构成该区的主要景观类型。冉家沟流域内几乎80%的土地出于中度土壤侵蚀状态,该区域内耕地面积略高于10%,林地总面积的比例大概在20%,灌丛面积比达到约35%。这一区域的景观类型是林地-耕地-灌丛-天然草地,也代表了冉家沟小流域的景观组成。强度土壤侵蚀地区是耕地集中的地区,现存耕地几乎全部在这一地区,占总面积的约43%。由于实施退耕还林和生物措施治理水土流失,一部分耕地退耕现为人工草地、幼林地或是新造林地。极强度土壤侵蚀地区在主沟的沟底部位,在该区分布有少量的天然次生林地和灌丛地。7)借助地理信息系统,结合前文的分析结果,对渭北黄土高原区冉家沟流域进行景观生态规划。在土地生态单元的划分上,选取了地形和土壤两个因子,将冉家沟划分为33个土地生态单元,并根据现实生产中最为突出的限制性因素和人为活动的可达性,将33个土地生态单元分为7类。根据地生态单元的适宜性评价结果,结合线性规划模型,进行各土地生态类型的土地利用优化配置和景观规划。以优化配置的结果来看,目前农业用地基本合理,林地尤其是生态防护林地面积比例低于优化后的总面积比例。经济效益高的经济林地和牧草地面积比例极不合理,各自仅占到流域总面积的0.34%和1.49%。更多还原

【Abstract】 Based on widely investigation of the condition of social-economic and natural environment in Ranjiagou watershed, depend on the topographic map in proportion 1: 10000, the land utilizationmap of 1999 and 2007, the reference of soil and vegetation, the vegetation landscape patch mosaic map was drawn practically in 2007 and DEM was made. The landscape pattern, distribution of vegetation with the topographic Variation were analyzed completely, supported by GIS, based the above study, we have made the landscape ecological planning and design, the main results were as following:1 ) Because of implementing Conversion of Cropland to Forest and Grassland in 1999 and biologic measures applying in soil and water conservation in 2003, the cropland were dramatically decreased from 1999 to 2007, mainly transformed into new plantation, artificial grassland and part of young plantation, proportion of forest and grazing in agriculture-forest-stockibreeding are increased.2) Applying 7 landscape indexes revealed the change characteristics and law of landscape pattern in Ranjiagou watershed under the comprehensive treatment policy, the change of land utilization is significant, diversity index and landscape dominance index are both increased, total number of patch decreased dramatically , distribution of landscape type tended to concentrate, landscape structure tended to be simplified.3) The elevation scale is relatively low. Cropland occupied the most area in elevation from 750 to 850 meters and has the largest percent; the land type that possesses the second area percent is Robinia pseudoacacia forest. In 850-950 meters region, natural forest have relatively small areas, by contraries another land type formed by human activity occupied the most areas in this region; the area percent of natural shrubs is as much as natural grassland. The main vegetation type in elevation 950-1050 meters are natural shrubs, grassland and forest. Vegetation types are decreased in 1150- 1130 meters region, Robinia pseudoacacia forest is the main vegetation type possessing 25% of total area in this region; Lespedeza bicolor Turcz., Indigofera Amblyatha shrubs took high proportion of the total area; Artem isia gm elinii took 15% of the total area.4) Cropland concentrated in region that under 25 degrees; Robinia pseudoacacia which has the largest areas in all forest distributed in region of 15 degree to 35 degree; though Populus davidiana, Platycladus orientalis widely distributed, the area of these two type forest occupied small proportion, which also distributed in unused land area; Lespedeza bicolor Turcz., Indigofera Amblyatha shrubs concentrated in 25 degree region; the more steep slope region are mainly distributed by Artem isia gm elinii5) Though Robinia pseudoacacia, Platycladus orientalis have large growth scale, the most area are distributed in shade and semi-shade hillside; Populus davidiana nearly all grow in this region. Distribution of natural shrubs is complex, Lespedeza bicolor Turcz most area concentrated in semi-shade hillside, by contrast Ziziphus jujuba Mill. var. spinosa have the largest area in sunny slope. Spodiopogon sibiricus have extensive growth scale from flat to semi-shady slope which adjacent by Artem isia gm elinii that distributed from semi-shade to sunny slope. Natural grassland, such as Artemisia argyi Levl. Et Vant.-Artemisia japonica Thunb. also concentrated in flat; cropland scattered all directions, most distributed in semi-sunny slope.6) In mild soil erosion region, cropland composed 20% of total area, forest 15%, shrubs and grassland nearly took 50% of the total area and were major vegetation landscape in this region. About 80% of areas are moderate soil erosion in which cropland took up 10%, forest 20%, shrub 35%. Forest-cropland-shrubs-natural grassland are composed the landscape structure in this region which also represented the landscape pattern in Ranjiagou watershed. Tension soil erosion region is the region in which cropland nearly all concentrated, occupied 43% of total area. Because implementing Conversion of Cropland to Forest and Grassland and biologic measures applying in soil and water conservation, some cropland transformed into artificial grassland, young plantation and new plantation. Extreme intensity soil erosion region located in gully bottom of major gully, some natural secondary forest and shrubs concentrated in this region.7) Based on the analysis results of previous paper, landscape ecological planning and designing were put forwarded by applying GIS. The results show that topographical features and soil are the two main factors influencing the land ecological type, the 33 land ecological cells in Ranjiagou were divided into 7 different land ecological types by highlighted restrictive factors and the accessibility of human activity in practice. Finally on the base of results of linear programming model making the ecological plan for the village, according these results, agricultural land is basically reasonable; forest land, especially the area of eco-protection forest is lower than the optimized forest area. The proportion of economic forest and grazing grassland are very unreasonable, possess only 0.34% and 1.49% of total area.更多还原