【作者】 张宏芝；

【导师】 朱清科；

【作者基本信息】 北京林业大学 ， 复合农林学， 2011， 博士

【摘要】 陕北黄土区由于地形高低起伏改变而形成了大小不等、形状各异的微地形,同时造成了坡面内局部土壤物理性状的差异,这种差异又造成了地表植被生长状况的差别,而地形和地表覆盖的共同作用影响着土壤理化状况的分布和运动,形成各种微地形特有的生境条件。本研究根据黄土区实际情况,对黄土坡面的微地形进行了研究,划分了浅沟、切沟、塌陷、缓台和陡坎五种微地形。本研究对不同微地形的土壤的质量进行了分析,探讨不同微地形的土壤在植被恢复过程中的演变,研究结果如下：(1)对自然恢复下的不同微地形土壤质量进行研究发现,微地形不同,其土壤理化性质也不同。其中,塌陷的土壤质量是最好的,切沟、缓台和浅沟居中,陡坎的土壤质量最差。塌陷和切沟的植被也得到了较好的恢复,并出现了马如子、锦鸡儿等小灌木。陡坎的土壤质量最差,其植被的盖度、高度也比较差。(2)在人工造林条件下,不同微地形的土壤质量与自然恢复下也不相同。切沟和缓台在人工造林下土壤质量最好,而自然恢复下土壤质量最好的塌陷,在人工造林状态下,其土壤质量比其他微地形差。(3)不同恢复方式对比发现,浅沟在三个土层中的,自然恢复和人工造林效果互有大小,但差值很小。自然恢复和人工造林土壤质量效果相当。切沟在0-20cm土层中,自然恢复的效果要好于人工造林,但在20-40cm和40-60cm人工造林要高于自然恢复。塌陷在0-20cm、20-40cm、40-60cm三个土层中不论是物理性质、化学性质还是酶活性自然恢复均比人工造林效果好,并且相差幅度比较大。缓台在0-20cm自然恢复的效果稍好于人工造林,在20-40cm和40-60cm土层人工造林高于自然恢复,但其差值很小。陡坎在0-20cm和40-60cm自然恢复对土壤质量好于人工造林,但差别极小,在20-40cm人工造林的对土壤质量高于自然恢复,差值不大(4)自然恢复条件下,恢复年限不同,地表植被也不同,对土壤质量的影响也不同。自然恢复50年后,地表植被形成了乔灌草相结合的结构类型,土壤的各项理化性质和酶活性都比自然恢复11年有了更大的提高,而且植被对土壤质量的影响也向更深土层发展。(5)不同植被配置的土壤进行土壤质量分析发现,油松纯林、沙棘纯林和油松沙棘混交林的土壤质量比较好,而山杏沙棘混交林和不采取任何恢复措施的对照较差。在0-20cm、20-40cm和40-60cm三个土层中,油松纯林的土壤质量是最好的,因此在黄土高原植被恢复的早期,可以种植油松林来促进植被的恢复。当然考虑到以后的森林健康和可持续发展,可以在植被恢复的不同时期进行其他林种的栽植,实现物种的多样性和适生性。综上所述,进行黄土高原植被恢复时,可根据具体情况采取不同的方法。切沟和塌陷的土壤质量在自然恢复下好于人工造林后,浅沟、缓台和陡坎的土壤质量自然恢复下和人工造林后差别不大。在进行植被恢复时,缓台和浅沟便于人工操作,进行人工植树种草难度比较小,因此可以采取人工造林的方式；陡坎建议自然恢复,这样还可以省去人工造林的人力、物力和财力。在人工造林中植被配置类型的选择上,可以考虑油松、沙棘以及油松沙棘混交的模式。更多还原

【Abstract】 In the Loess Plateau in northern shananxi, the wavy change of terrain in the hilly-gully region consequently forms the micro-topography of varying shapes and sizes, at the same time, causes the differences in physical property of the local soil on slope surface.It is these differences that result in the distinction of growth condition of the vegetation.What’s more,the joint action of both terrain and surface coverage affects the distribution and movement of the physical and chemical properties of the soil, forming the unique habitat condition for various micro-topographies.Based on the actual situation of the hilly-gully region, the research studied the micro-topography on the loess slope. divideing it into five types such as ephemeral gully, gully, collaps, eplatform and scarp.In this study,the different qualities of soil in micro-topography are analyzed to explore the evolution of soil in the process of revegetation.The results are as follows:1.According to the study on the soil quality of the different micro-topographys in natural recovery, it is found that different micro-topography has different physical and chemical properties of soil. Among them,the soil quality of collapse is the best, gully,platform and ephemeral gully are the worse, scarp is the worst. The vegetation of collapse and gully has been well restored and even appeared Maru Zi, Caragana and some other small shrubs in those years. The soil quality of scarp is worst, so are the vegetation of coverage and height.2.Under the artificial afforestation condition,the soil quality of different micro-topography is distinguished from that of the natural recovery. Under the artificial afforestation condition,the soil quality of gully and platform is the best,however,The soil quality of the collapse,which is the best performer in natural recovery,is poorer than the other terrains.3.Through the comparison of different recovery modes, in three soil layers,the effection of the natural recovery and the artificial afforestation is similar. The soil quality of ephemeral gully in natural recovery is better than that in artificial afforestation. Gully in the 0-20cm soil layer achieves better results in natural recovery than that in artificial afforestation. However, it is just opposite in the 20-40cm and 40-60cm. The natural restoration of Collapse performs better whether in physical property,chemical property or enzyme activity in the 0-20cm,20-40cm and 40-60cm and the balance is relatively large. Platform receives effect slightly better in natural recovery in the 0-20cm but the artificial one wins with small difference in the 20-40cm and 40-60cm.Both of natural restoration and artificial afforestation play an equal role in progressing the soil quality for Platform, but artificial afforestation is conducive to improve the soil quality of deeper layers. The natural recovery of scarp reaches greater improvement in the 0-20cm and 40-60cm than the other one, but the balance is extremely small. In 20-40cm, the artificial beats the natural with narrow gap,which turns out that the scrap is in the same case of the platform.4.Under the conditions of natural recovery, Soli quality was affected by dfferernt type of their restored years and vegetation. After 50 years of natural recovery, the structure type of trees brushes and graaaes was formed, and the soil quality of physical and chemical properties was much greater than of 11 years’,with soil recovery developing from the shallow soil layer to the deeper one.5.The study on soil quality The study on the soil quality cllocated by different vegetation shows that,the soil quality restores perfectly in chinese pine fores、hippophae rhamnoides forest and mixed forest of pine and hippophae rhamnoides.On the contrary,the soil in apricot and hippophae rhamnoides forest along with the vegetation lacking of recovery measures is relatively poor.At layer 0-20cm、20-40 cm and 40-60cm, chinese pine forest is the best,so in the early vegetation restoration, recovery can be promoted with its help.Considering the healthy and sustainable development of forest in the future, some other species can be planted to fit for the different stage of restoration.In conclusion,different approaches corresponding to the specific circumstances can be adopted to restore vegetation in the Loess Plateau. The soil quality of gully and collapsed under the natural recovery is better than in artificial afforestation, ephemeral gully(EG)、platform and scarp is not significant. During the vegetation recovery, platform and ephemeral gully(EG) can be taken artificial afforestation, because of the easy manual,planting trees and grass; Scarp suggests natural recovery,and it will save human、material and financial resources. In the choice of the type of vegetation collocation, chinese pine、hippophae rhamnoidesand or the mixed mode of chinese pine and hippophae rhamnoidesand can be taken into consideration.更多还原