Selection On Suitable Trees In Semiarid Loess Hilly And Gully Area

In semiarid loess hilly and gully area, it is the important access to ecological rehabilitation in ecological fragile area that vegetation restoration and reconstruction, while the suitable trees selection is the basis for vegetation restoration. The objective of rehabilitating fragile ecological environment can be achieved only by according to afforestation requirement, complying with the principle of suitable trees for suitable area and selecting suitable trees mainly local trees. The Anjiagou catchmnet of Anding district, Dingxi city, is the typical and representative area in semiarid loess hilly and gully area. Through generally investigating arbor and shrub resources including their distribution, quantity and growth and so on in Anjiagou catchment and determining the main trees' physiological indicators such as total water content, free water content, bound water content, relative water content, transpiration ratio, water scarcity and water potential etc., after comprehensively analyzing and evaluating the adaptability of various trees in the trial area, 13 species of arbor and shrub were selected of Platycladus orientalis, Pinus tabulaeformis, Picea asperata, Robinia pseudoacacia, Populus hopeiensis, Salix withelmsiana, Prunus armeniaca var. ansu, Ailanthus altissinia, Ulmus pumila, Tamarix austrmongolica, Caragana intermedia, Hippophae rhamnoides subsp sinensis and Elaeagnus angustifolia, which are the main extension tree species in afforestation production and environmental greening in semiarid loess hilly and gully area. Also, the production problems were put forward in the paper, which provided the basis for future trees selection and theirs rational collocation. At the same time, 11 tree species were introduced and made cultivation trial in terms of the principle of climate similarity and field similarity. Through observing and analyzing the introduced trees, 6 tree species among them were selected of Juniperus rigida, Caragana stenophylla, Amorpha fruticosa, Rhus typhina, Atraphaxis bracteata and Platycladus orientalis cv Sieboldii, which can be introduced and extended in semiarid loess hilly and gully area, but their adaptability need further study. The trial result indicated that the techniques of container seedling afforestation and delve covering afforestation can improve survival rate of afforestation significantly, which are afforestation techniques deserved to extend and apply in semiarid loess hilly and gully area.