科尔沁沙地灌木对风沙土壤的生态效应

Study on ecological effects of several shrubs on sandy soils in Horqin Sandy Land

对科尔沁沙地小叶锦鸡儿、差巴嘎蒿和黄柳灌木阻固沙尘和保育土壤的生态效应进行了野外定株观测研究.结果表明:(1)小叶锦鸡儿阻固沙尘的能力很强,单株灌木基部的平均积沙(尘)量为0.49m3,分别是差巴嘎蒿和黄柳的3倍和16倍.(2)每一灌木种的冠幅直径、基部分枝数和分枝直径均与灌木基部的积沙(尘)量有显著的正相关关系,其中冠幅直径对积沙(尘)量的影响最大,决定系数为0.18～0.58(P＜0.05,n=30).(3)三种灌木对土壤有机质、全P、全N和速效P都有不同程度的富集作用,其中对土壤有机质的富集作用更为明显;不同灌木种间,小叶锦鸡儿对土壤有机质和全N的富集作用略大于差巴嘎蒿和黄柳.

Abstract： In this study, we examined the pedoecological effects of three shrub species that occur generally in shifting, semi-shifting and semi-fixed sand lands in the Horqin Sandy Land. Several important conclusions were drawn from this study. （1） There were significant differences in the interception and retention of sand and aeolian dust among three shrub species. Of the three shrubs, the mean amount of the interception and retention of sand and aeolian dust per plant was the greatest （0.49 m^3 ） in Caragana microphylla, followed by Artemisia halodendrom （0.16 m^3 ） and Salizc gordejvii （0.03 m^3）. Regression analyses showed that the sediment amount of sand and aeolian dust per plant was positively and significantly correlated with its average canopy （accounting for 18-58% of the variance）, branching number （accounting for 16-31% of the variance） and shoot diameter （accounting for 14-17% of the variance）. （2） All three shrubs exhibited significant effects of “island of fertility”, i.e. the soils under shrub canopies were significantly higher in nutrient availability than those beyond shrub canopies. Such effects may create a nutrient-rich substrate, thus providing a better environment for further invasion and establishment of other plant species on bare sandy land. The effects of “inland of fertility”varied markedly with the type of shrub species. Of the three shrubs examined, Caragana microphylla had the greatest “fertile island”effect, followed by Artemisia halodendrom and Salix gordejvii, largely because of significantly higher levels of organic matter, total N and available P in soils （0-20 cm） under the Caragana microphylla canopies than those under Artemisia halodendrom and Salix gordejvii canopies. Shrubs differed appreciably in accumulation efficiency of different nutrients. For example, the accumulation efficiencies of organic matter, total P, available P and total N in soils under shrub canopies averaged 1.20-1.44, 1.08-1.23, 1.11-1.36 and 1.17-1.40. （3） Wind direction appeared not to influence the spatial distribution of soil physical properties, but showed an effect on the spatial distribution of organic matter content. Organic matter tions of the shrubs were somewhat higher than contents in soils at the SE and NE directhe other directions.