青藏高原东北部黄土区灌木幼林根系护坡的时间效应

Time effect of young shrub roots on slope protection of loess area in Northeast Qinghai-Tibetan plateau

为研究青藏高原东北部黄土地区植物护坡效应的可持续性,选取种植在自建试验区的四翅滨藜、柠条锦鸡儿、白刺、霸王4种灌木植物,分别对生长时间为1～4a的上述灌木进行了野外现场拉拔试验。试验结果表明,4种灌木植物在其1～4a的生长时间里,四翅滨藜的抗拔力和侧根数在4种灌木中表现最大,霸王的根径是4种灌木中最大的;生长时间为1a的4种灌木中霸王地径最大,其后的2～4a生长时间中,四翅滨藜的地径则在4种灌木植物中表现最大。霸王和白刺的平均根径与生长时间之间呈显著幂函数关系,四翅滨藜和柠条锦鸡儿两者之间均呈指数函数关系;四翅滨藜和白刺的平均侧根数与生长时间之间呈显著的幂函数关系,霸王和柠条锦鸡儿的平均侧根数与生长时间之间呈线性函数关系;四翅滨藜和白刺的平均地径与生长时间之间呈幂函数关系,霸王和柠条锦鸡儿的平均地径与生长时间之间呈指数函数关系;四翅滨藜和柠条锦鸡儿的平均抗拔力与生长时间之间呈显著幂函数关系,霸王的平均抗拔力与生长时间之间呈线性函数关系,白刺的平均抗拔力与生长时间之间为指数函数关系。这种现象反映了4种灌木植物在试验区边坡防护中均表现出了较强的护坡可持续能力。

To study the persistence effect of plant roots in slope protection of loess area in the northeast of Qinghai-Tibetan plateau, four shrubs Atriplex canescens、Caragana korshinskii、Nitraria tangutorum、Zygophyllum xanthoxylon were planted on the slopes of the test area. Field situ pull-out test was applied to test the four shrubs with one-year growth period or four-year growth period. The result showed that during the four years, the pull-resistance、lateral root quantity of Atriplex canescens were the largest, and the root diameter of Zygophyllum xanthoxylon increased fastestly among the four shrubs; and the root diameter of Zygophyllum xanthoxylon increased faster than that of the other three shrubs during the first year, and the root diameter of Atriplex canescens increased faster than that of the other three shrubs from the second year to the fourth year. There was a power function between average root diameter and growth time for Zygophyllum xanthoxylon and Nitraria tangutorum, an exponential function for Atriplex canescens and Caragana korshinskii, a power function between average lateral root quantity and growth time for Atriplex canescens and Nitraria tangutorum, a linear function for Zygophyllum xanthoxylon and Caragana korshinskii, a power function between the average root diameter and growth time for Atriplex canescens and Nitraria tangutorum, an exponential function for Zygophyllum xanthoxylon and Nitraria tangutorum, a power function between average pull-resistance and growth time for Atriplex canescens and Caragana korshinskii, and a linear function for Zygophyllum xanthoxylon, for Nitraria tangutorum was an exponential function. The research indicated that all the four shrubs showed a powerful persistent capability in slope protection.