六盘山生态移民迁出区不同植被恢复模式TOPSIS综合评价

TOPSIS evaluation of different vegetation restorations models in eco-emigration area of Liupanshan

宁夏南部山区是经济欠发达地区,通过生态移民迁出可降低人口对环境的压力,但移民迁出后如何进行生态系统恢复仍不明确.本研究以六盘山海子流域生态移民迁出后设计的6种植被恢复模式为研究对象,即青海云杉(Picea crassifolia)+油松(Pinus tabuliformis)+河北杨(Populus hopeiensis)、刺槐(Robinia pseudoacacia)+油松、旱柳(Salix matsudana)+刺槐+山杏(Prunus armeniaca)、油松+山杏、刺槐+山杏+紫花苜蓿(Medicago sativa)、油松+旱柳+红豆草(Onobrychis viciaefolia),通过调查其土壤养分指标和树木生长指标,以TOPSIS法对恢复效果进行综合评价.结果表明:①所有植被恢复模式均能够增加土壤碱解氮含量(38.7%~280.4%)和土壤有机质含量(16.5%~298.9%),但降低了土壤速效磷含量(-82.9%~65.2%).②植被恢复模式配置的树种中,青海云杉、油松、河北杨和刺槐均能够正常生长,山杏幼苗生长不良,死亡率较高.③TOPSIS综合评价表明,青海云杉+油松+河北杨模式效果最佳(Ci=0.799 9),其次为油松+旱柳+红豆草(Ci=0.537 8)、刺槐+油松(Ci=0.526 3),油松+山杏模式综合评价最低(Ci=0.119 9).研究表明乔木针阔混交的植被恢复模式更适于研究区;在林分形成郁闭抑制林下野生草本后,配置耐阴灌木和草本,利于稳定生态系统的形成.

Because of less developed economy and fragile ecosystem in southern mountain area of Ningxia province, how to restore abandon farmland and ensure the effect of vegetation restoration on ecosystem are urgent problems after moving population. Six vegetation restoration models(Picea crassiflolia+Pinus tabuliformis+ Populus Hopeiensis, Robinia pseudoacacia+Pinus tabuliformis, Salix matsudana+Robinia pseudoacacia+Prunus armeniaca, Pinus tabuliformis+Prunus armeniaca, Robinia pseudoacacia+Prunus armeniaca+Medicago sativa, Pinus tabuliformis+Salix matsudana+Onobrychis viciaefolia)were conducted in Haizi of Liupanshan mountain. The soil fertility(TN, AN, AP, AK, SOC) and tree growth index(height, diameter, crown width, new branch length, new branch diameter, survival rate) were measured to evaluate the vegetation restoration by TOPSIS. The result showed that(1) all the restoration models increased AN(38.70%~280.64%) and SOC(16.48%~298.88%), but decreased the AP(-82.90%^-65.20%).(2)All tree species had high survival rate except Prunus armeniaca.(3)TOPSIS evaluation indicate that Picea crassiflolia+Pinus tabuliformis+ Populus Hopeiensis model had the highest score(Ci=0.799 9), and the next were Pinus tabuliformis+Salix matsudana+Onobrychis viciaefolia model(Ci=0.537 8) and Robinia pseudoacacia+Pinus tabuliformis model(Ci=0.526 3). Pinus tabuliformis+Prunus armeniaca model had the least score(Ci=0.119 9). Our research imply that conifer and broadleaf mixed model is suitable for research area. The shrub and grass species with shade tolerance could be introduced after canopy closed.