【作者】 许晓波；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 植物学， 2008， 博士

【摘要】 本文利用地理信息系统技术并结合地面标准地调查结果，对刚开始恢复治理的县南沟和已经治理三十多年的纸坊沟流域的植被景观格局特征、植被景观组成要素特征、植被景观斑块大小的分布特征、斑块形状的指数分析、景观多样性和破碎化等方面进行分析并比较两流域的异同之处；分析了两流域典型生态系统的生长、更新、生物多样性、土壤水分养分、环境因子等特征，并对典型生态系统的稳定性进行了综合评价，为流域内生态系统空间格局的合理配置、健康的流域环境建设提供科学依据。得出以下结论：(1)两流域景观格局基本特征相似：纸坊沟流域经过三十多年的治理，植被生态系统的景观布局相对合理，生态防护型森林、草地景观占有较高比例，二者面积之和达5．647 km~2，占整个流域面积的68．24％，周长之和为172．54km，占全区的62．67％。县南沟流域从2000年开始治理，森林、草地等其他景观参数与纸坊沟流域相似，灌丛、农田、果园等类型占景观斑块的面积比例不足40％；各景观类型拥有的斑块数极不均衡，流域景观组分的斑块数、斑块比例，以及一个景观组分在整个流域景观中的密度和各个景观组分的斑块密度等指标差异显著，无明显的规律。(2)纸坊沟流域景观多样性指数高，优势度指数低，县南沟流域优势度指数高，而多样性指数低；整体上，纸坊沟流域破碎化指数高于县南沟流域。流域景观格局多样性指数与生态经济系统健康系数比较表明，纸坊沟流域生态经济系统健康指数提高、景观多样性指数增加的同时，导致破碎化指数增加。(3)对两流域内四个典型生态系统稳定性分析表明：沙棘在黄土丘陵区更新良好，在非阳坡地段，幼龄、中龄个体多，属于进展型的种群，能够长期稳定存在下去；半阳坡和半阴坡地段的沙棘林具有较高的物种多样性，较优越的土壤水分、养分条件，这些对群落稳定发展提供了保障。小叶杨在黄土丘陵区更新困难，不同生境研究表明：小叶杨在阳坡更新困难，相比较而言，在水分条件较好的阴坡、沟谷等地段小叶杨长势较好，并产生少量幼苗，具有较高的物种多样性，土壤水肥条件达到最好，但仍不能改变整个种群的衰退趋势，其所在群落也不稳定。狼牙刺在黄土丘陵区的半阳坡和阳坡上都能够很好的自我更新，中幼龄个体多，属于进展型的种群，种群能够长期稳定存在下去。在半阳坡和阳坡上都具有较高的物种多样性，群落稳定。刺槐在阳坡没有更新的幼苗，随着时间的推移刺槐种群将会死亡，相比较而言，沟谷和半阴坡有更新的幼苗较为适宜刺槐生长，在半阴坡和沟谷具有较高的物种多样性。在阳坡水分尤其亏缺，影响了刺槐的生长。(4)本研究应用Fuzzy数学中隶属函数的方法对典型生态系统稳定性进行综合评判，评判结果是：沙棘半阴坡最稳定；小叶杨阴坡最稳定；狼牙刺阳坡最稳定；刺槐沟谷最稳定。景观格局的合理性是一个相对的概念，经过三十多年治理，纸坊沟流域生态系统基本上已经进入了良性循环阶段，植被景观布局比较合理，生态防护型林草植被景观的面积比例已经达到历史最高水平，生产经济型农田、果园景观和生活服务型河流、水库、居民点景观比例与人口及社会发展相适宜，可作为黄土丘陵沟壑区植被治理的重要参考。县南沟流域的植被治理可参考纸坊沟流域的治理模式进行治理。但纸坊沟流域内局部景观布局也有不够合理的方面，如人工林(刺槐、小叶杨)的“土壤干层”“小老树”、人工草地(苜蓿)“周期性衰退”等问题，需要在未来景观格局调整中不断完善。更多还原

【Abstract】 This paper,in accordance with the GIS technology in combination with the findings ofground survey,the vegetation landscape elements pattern characteristics,the distributingcharacteristics of the vegetation landscape patch size,the patch shape indices,landscapediversity index,fragmentation degree,and so forth of Xiannangou watershed that was justmanaged in recent years and Zhifanggou watershed that was managed for more than 30 yearswere analyzed.The growth,updating,biodiversity,soil nutrition and water and environmentfactors and so on of the typical eco-system were analyzed and evaluated.The aim offered thescientifical foundation for the landscape pattern’s sensible distribution and watershedenvironment construction.The main results were as following:(1)The landscape pattern is similar basically in two watersheds:Through more thanthirty years management,the vegetation eco-system pattern in Zhifanggou watershed isrelatively reasonable,and the proportion of eco-protection forest and grassland is higher thanother landscape types.The area of forest and grassland come to 5.647 km~2 with 68.24 % ofZhifanggou watershed.the perimeter of eco-protection forest and grassland come to 172.54km with 62.67 % of Zhifanggou watershed.The proportion of forest and grassland is alsohigher than other types in Xiannangou watershed,the other landscape parameter were justsimilar with Zhifanggou watershed.The total area of shrub,farmland,orchard,and so on wasrelatively small,with lower than 40 percent of the whole Xiannangou watershed.The patchnumber of different landscape types was very disproportion.There is no obvious regularbetween different landscape types in the term of the number of patches,the proportion ofpatches,the density of patches,and the difference of the different landscape type index wasvery significance.(2)The landscape diversity indices of Zhifanggou watershed were higher thanXiannangou watershed,but the dominance degree in Zhifanggou watershed was lower than inXiannangou watershed.And the fragmentation index in Zhifanggou watershed is higher thanin Xiannangou watershed as a whole.With the increase of eco-economic health index andlandscape diversity index,the fragmentation index will increase in the mean time,accordingto the comparing of landscape diversity index and eco-economic system health index. (3)The analysis of the four typical eco-system stabilities showed:Hippophae rhamnoidecould renew very well in Hilly-gully region of Loess plateau.The number of youth and adultswas large on half-sunny,half-cloudy slope and cloudy slope,which showed that thispopulation was a developing one,and could survival in the future.There were higherbiodiversity and better moisture and nutrition in soil in this population on the half-sunny andhalf-cloudy slope which provided a guarantee for community stabilizing gradually.ThePopulus simonii population renew difficultly in Hilly-gully region of Loess plateau.The resultof research on different habitats showed that this population could not renew at sunny slope.Compare with in the sunny slope,there were growing well Populus simonii,several seedlingsappeared higher biodiversity and better soil nutrient content in the cloudy slope.But thesecould not change the declining trend of the whole population.Sophora davidii can renew wellin half-sunny slope and sunny slope,the individual number of middle aged were many,Sophora davidii population in Hilly-gully region of Loess plateau was a developing one,Sophora davidii population could survived for long in different habitat in Hilly-gully regionof Loess plateau.Diversity was high,community was stability more and more,water andnutrition was better in half-sunny slope and sunny slope.Community was more stability.Robinia pseudoacacia population had not renewed seeding in the sunny slope.Robiniapseudoacacia population in loess hilly region was a recession one,that is not stabilitypopulation,would disappear with the development of time in the sunny slope,but was fitterand had the renewed seedlings basically in the half-cloudy slope and gully and valley.Diversity was high in the half-cloudy slope,gully and valley.Water was serious shortage inthe sunny slope,which affect grow of Robinia pseudoacacia.(4)This paper applied the method of the membership function of Fuzzy mathematics toevaluate the typical eco-system stability.The results showed that Hippophae rhamnoide,Populus simonii,Sophora davidii and Robinia pseudoacacia were more stability in thehalf-cloudy slope,cloudy slope,sunny slope and gully and valley respectively.The rationality of landscape pattern was a relative conception.Through conservation forabout 30 years,eco-system had already entered basically positive cycle stage in Zhifanggouwatershed,the vegetation landscape layout had been reasonable comparatively,the areaproportion of the eco-protection forest,shrub and grassland landscape had got to the historicalmaximum level,the area proportion of the pro-economics farmland and orchard landscapeand the living-service river,dam,settlement landscape were suitable for the population andsocial development,might take it as the important reference of the vegetation conservation inHilly-gully region of loess plateau.But the partial landscape layout also existed unreasonableaspects,for example,artificial forests (Robinia pseudacacia、Populus simonii) existed“dried earth layers”and“lower-yields stands”,artificial grassland (Medicago sativa) existed“theperiodicity declines”and so on,would need adjust landscape pattern and made itconsummation unceasingly in the future.更多还原