排土场典型树种穿透雨空间分布特征

Spatial Distribution Characteristics of the Throughfall for Typical Tree Species in Dump Site

穿透雨是降雨再分配的主要组成成分,影响植被生长以及土壤水分分布情况,研究矿区典型树种穿透雨特征对生态恢复具有重要意义。以平朔矿区南排土场典型树种为研究对象,利用地统计学方法与时间稳定性图对比分析了油松(Pinus tabulaeformis)、刺槐(Robinia pseudoacacia)、白杜(Euonymus maackii)、小叶锦鸡儿(Caragana microphylla)和木半夏(Elaeagnus multiflora)的穿透雨空间分布特征。结果表明:(1)平均穿透率由大到小为木半夏、小叶锦鸡儿、油松、白杜、刺槐,穿透率变异系数由大到小依次为白杜、木半夏、小叶锦鸡儿、油松、刺槐。(2)油松、刺槐、白杜、小叶锦鸡儿与木半夏的穿透率均随降雨量的增加而增加,最后达到平稳状态,降雨量增大,穿透率变异系数先快速下降,最后达到平稳状态,并都以对数函数拟合效果最好。(3)5种树种穿透率的基台值均随着降雨量增加呈指数减小,块金系数随着降雨量的上升而增加,表明随着降雨量的上升,冠层穿透率在空间上趋于均匀化,随机因素带来的空间变异性逐渐增大。此外,5种树种在植株冠层中部和外缘部分均出现穿透率高于100%的情况。(4)灌木穿透雨分布格局的时间稳定性比乔木高,冠层接近基部和外缘出现穿透雨极端稳定性,接近植被基部多为极端干燥状态,冠层外缘多为极端湿润状态。(5)从穿透率大小及其空间变异性考虑,在排土场水土流失地区刺槐为最佳重建植被类型选择,穿透雨在植被冠幅边缘出现持续湿润状态,可种植一些灌木来截留一部分穿透雨。研究结果增进对矿区排土场生态水文过程的认识,可为矿区排土场重建植被选择提供理论基础。

Throughfall is the main component of rainfall redistribution, which affects vegetation growth and soil moisture distribution. Taking the typical tree species in the southern dump of Pingshuo mining area as the research object, the spatial distribution characteristics of throughfall of Pinus tabulaeformis, Robinia pseudoacacia, Euonymus maackii, Caragana microphylla and Elaeagnus multiflora were compared and analyzed by using geostatistical methods and time stability plots. The average throughfall percent from large to small was: Elaeagnus multiflora, Caragana microphylla, Pinus tabulaeformis, Euonymus maackii, Robinia pseudoacacia. The coefficient of variability of throughfall percent from large to small was Euonymus maackii, Elaeagnus multiflora, Caragana microphylla, Pinus tabulaeformis, Robinia pseudoacacia. The throughfall percent of Pinus tabulaeformis, Robinia pseudoacacia, Euonymus maackii, Caragana microphylla and Elaeagnus multiflora increased with the increase of rainfall, and finally reached a steady state, and the coefficient of variability of throughfall percent decreased rapidly with the increase of rainfall, and finally reached a steady state, and the logarithmic function was the best fitting effect. The still of throughfall percent decreased exponentially with the increase of rainfall, and the nugget coefficient increased with the increase of rainfall, indicating that with the increase of rainfall, the throughfall percent tended to be uniform in space, and the spatial heterogeneity caused by random factors gradually increased. Moreover, the throughfall percent of the five tree species was higher than 100% in the middle and outer parts of the plant canopy. The temporal stability of the distribution pattern of throughfall shrubs was higher than that of trees. The canopy near the base and the outer edge of the canopy showed extreme persistence of throughfall. The base near the vegetation was mostly in an extremely dry state, and the outer edge of the canopy was mostly in an extremely wet state. Considering the throughfall percent and its spatial variability, Robinia pseudoacacia was the best choice of vegetation type for reconstruction in soil erosion areas. The throughfall appeared continuously wet at the edge of the vegetation canopy, and some shrubs could be planted to intercept part of the throughfall. These research results could enhance the understanding of the ecological and hydrological process of the mining dump, and provide a theoretical basis for the selection of vegetation for the reconstruction of the mining dump.