黄土区露天煤矿排土场不同微地貌土壤种子库特征

黄土区露天煤矿排土场边坡水力冲刷强烈,不同植被恢复模式与水力作用耦合形成的不同微地貌可通过对种子的不同拦截作用而影响植被的恢复及发展。为了探讨排土场不同微地貌对种子的拦截效益及不同植被恢复模式的恢复潜力,选取不同恢复模式下形成的细沟、丛岛和草带三种微地貌为研究对象,以邻近裸坡为对照,研究不同微地貌土壤种子库特征及其拦截力。结果表明：（1）在不同微地貌中土壤种子库均以一年生藜科和禾本科植物为主;丛岛微生境的土壤种子库中有较丰富的物种和较高的多样性指数。（2）各微地貌的土壤种子库均具有表层聚集现象;草带微地貌中的土壤种子库总储量最大,且草带的0-2 cm土层处的土壤种子库密度显著高于各微地貌的各个土层（P<0.05）。（3）细沟和丛岛在上坡位对种子的拦截效果更好,草带在下坡位对种子的拦截效果更好。综上所述,沙蒿恢复模式形成的丛岛有利于增加土壤种子库的物种多样性,草带有利于增加土壤种子库的储量,故在黄土区排土场进行植被恢复时可以利用不同微地貌对土壤种子库分布特征的优势构建适宜的复合植被恢复模式。

Characteristics of soil seed bank in different micro-topographies of opencast coal mine dumping site in loess area

The serious hydraulic scouring of the unstable slopes of dumps in opencast coal mines in loess areas can easily induce variously geological hazards. In the process of vegetation restoration, different micro-topographies formed by the coupling of different vegetation restoration modes and hydraulic effects can affect the restoration and development of vegetation through different interception effects on seeds. In order to investigate the seed interception benefits of different micro-topographies in dumping sites and the restoration potential of different vegetation restoration modes, three micro-topographies formed under different restoration modes, namely, rill, scrub mound and grass strip, were selected as research objects in this study. The adjacent bare slopes were used as controls to study the characteristics of the soil seed bank and its interception power by measuring its soil seed bank storage, calculating the species diversity index and seed interception index. The results show that:(1) the soil seed bank in all micro-topographies was dominated by annual Chenopodiaceae and Gramineae; the soil seed bank in the scrub mound had richer species and higher diversity index. (2) The soil seed bank in all micro-topographies had superficial aggregation; the total soil seed bank in the grass strip micro-topographies had the largest storage capacity, and the soil seed bank density at the 0-2 cm soil layer in the grass strip was significantly higher than that in each soil layer of each micro-topography (P<0.05). (3) The seeds were better intercepted in the upper slope by the rill and scrub mound, with a seed interception index of 0.58 and 0.27, respectively; and the seeds were better intercepted in the lower slope by the grass strip, with a seed interception index of 0.60. In summary, the scrub mound formed by the Artemisia desertorum restoration model was conducive to increasing the species diversity of the soil seed bank and more effective in intercepting seeds on the upper slopes; and the grass strip was conducive to increasing the storage capacity of the soil seed bank and more capable of intercepting seeds on the lower slopes. Therefore, when revegetating dumping sites in loess areas, the advantages of different micro-topographies on the distribution characteristics of the soil seed bank should be used to build a suitable composite vegetation restoration model.