黄土丘陵区狼牙刺种群恢复及群落土壤水分养分效应

以荒草坡为对照,对黄土丘陵区封禁8年、20年和30年的狼牙刺群落的狼牙刺种群结构及群落土壤水分和养分的特征进行了系统研究,分析了群落恢复与环境因子的关系。在黄土丘陵区,狼牙刺群落通过封禁能够恢复,经过20年恢复种群可达到相对稳定的状态;不同恢复阶段的狼牙刺种群密度、个体平均基径、高度和生物量差异明显:30年>20年>8年>荒草坡。随着狼牙刺群落恢复,种群幼龄个体减少,中老龄个体增加,但种群仍保持扩展趋势,具有进一步发展潜力。不同恢复阶段狼牙刺群落内土壤水分出现了微弱干层,并随根系延伸下移。土壤养分在群落恢复初期增加较快,后期比较稳定。影响狼牙刺群落恢复和种群生长的环境因素主要是水分因子,其中土壤水分、群落盖度比较重要。狼牙刺适应力、繁殖力强,种群具有扩展潜力,未来应该充分利用其优良特性,继续保持现有的封禁措施,促进群落进一步恢复和环境条件的改善。

Recovery of Sophora davidii Populations and Efficiency of Soil Water and Nutrition of Communities in Loess Hilly Area

Sophora davidii is constant secondary shrubbery in loess hilly. Sophora davidii can develop pure shrubbery or play dominant species roles in plant community in sunny slope and half sunny slope where the other arbor and shrub trees survive difficultly in loess hilly area,which plays important role in water and soil conservation as well as soil improvement. Barren grass land as control area, Sophora davidii population structures and the characters of soil water and soil nutrition in different stage of recovery in Sophora davidii communities that was closed for 8 years, 20 years and 30 years in loess hilly were researched systematically. The analysis on relationships between recovery of community and environment factors were made. The results showed: Sophora davidii communities could be restored by closing management in loess hilly, and Sophora davidii populations could reach relative stable stage after closing for 20 years. The density, mean basal diameter, height and biomass of Sophora davidii populations in different stages of recovery is significant different: height 30 years>height in 20 years>height in 8 years>barren grass land. With the recovery of Sophora davidii community, the number of young-age Sophora davidii individuals was declined, and the number of and middle-old-age individuals was increased, but Sophora davidii population still keep trend of expanding and with developing potentiality gradually. Soil water show feebly dry layer in Sophora davidii community of different stage of recovery, and extended downward with roots of Sophora davidii individuals. Increase of soil nutrients in beginning period of recovery is quick, but is stable in last period. Environment factors that affect Sophora davidii community recovery and the population development is water factor, such as soil water and coverage of community is comparative important. Sophora davidii has strong compatibility and reproduction and population has expanding potentiality, and its excellent characters should be made use, keeping continue forthcoming closing management in order to accelerate recovery of Sophora davidii community gradually and improve condition of environment.