New Restoration Engineering in Northeast Asia

摘要

The environmental conditions of desertifed areas differ from those where natural regeneration of shrubs and trees occurs, and the revegetation process can be acceletated by planting shrubs and trees. A variety of countermeasures including constructing sand barriers, planting trees and establishing appropriate stocking rates must be implemented under careful consideration of both local socio-economic demands and the degraded environmental condition. This article presents the results of some revegetation trials the author undertook in China and Mongolia. It describes how countermeasures to prevent sand drift and soil erosion are needed in accordance with varying site conditions. For example, in sandy soil, sand barriers are effective at stabilizing land surfaces, whereas, in clayey soil conditions, water harvesting to prevent run-off is a useful way to protect the site's condition. In ecological restoration, proper selection of plant materials is important in terms of vegetation enrichment and social benefits. Once vegetation has been established, its consumption of water will have a strong effect on soil moisture content. Long-term density control with frequent monitoring of environmental changes is necessary to maintain the restored ecosystem in sound condition. Thirty percent is the threshold value of coverage to stabilize sand surfaces irrespective of vegetation type. Indigenous plants are the most advisable species for greening. When seedlings are introduced into an arid land system, site preparation is the main factor helping them overcome the first dry season after planting. Site preparation centers on improving the moisture supply to the seedlings and reducing overall moisture loss by eliminating weeds to mitigate environmental stress.