关键词: 反馈效应, 黄土高原, 土壤干化, 植被建设

Abstract:

Owing to vegetation construction in the Loess Plateau, much attention has been paid to soil desiccation by vegetation for many years. Right thinking about soil desiccation by vegetation would conduce to controlling it, and furthering reasonable management and evolution of vegetation. The feedback response of vegetation to soil desiccation by itself is mainly discussed in this paper. We believe that the phenomenon of soil desiccation by vegetation occurring universally in the Loess Plateau just reflects environmental limitation on vegetation from a peculiar angle. Because artificial forest and grass vegetation is weak in the mechanism of negative feedback regulation compared with natural vegetation, the contradictory show between water use by plant growth and water supply by environment constitutes a so serious threat to stability of artificial forest and grass vegetation that it grows slowly and even declines, and commonly takes marked restraining effect on development of follow- up plant rooting deep after vegetation declination. But on the other hand it is noticeable that follow- up natural vegetation or plant rooting superficially still may succeed to grow well. It is obvious that soil desiccation by vegetation isn ’t favorable for seeking economical goal, but it would uncertainly cause a negative effect on protection of soil from erosion. The stability of artificial forest and grass vegetation should be treated respectively according to their managing goals. The research on naturalizing process of artificial forest and grass vegetation would be a significant proposition related to ecological restoration.

Key words: feedback effect, Loess Plateau, soil desiccation, vegetation construction