黄土丘陵沟壑区潜在抗侵蚀植物分析

基于对黄土丘陵沟壑区延河流域多年(2003—2014年)植被调查资料的整理分析,根据抗侵蚀植物定义及Braun-Blanquet植物社会学方法,筛选该区潜在的抗侵蚀植物,阐明不同抗侵蚀植物的分布特征及其生存繁衍能力。结果表明:1)共筛选出潜在的抗侵蚀植物42种,分属18科33属,禾本科、豆科、菊科、蔷薇科物种最多,占总物种数的66%。2)42种植物中85%的物种生活型为高位芽、地上芽和地面芽植物,76%的物种生长型为灌木/小灌木和多年生草本,78%的物种水分生态类型为旱生和中生;结合该流域的气候条件及42种植物的分布范围,可将其分成广幅种、中幅种、窄幅种3种类型。3)55%的物种最大盖度超过50%,可成为群落的建群种或单优种;其它最大盖度小于50%的物种多成为群落的共优种,这些物种具有较高的盖度和地上生物量,表明植物能适应该区侵蚀环境且长势较好。4)42种植物几乎都具有土壤种子库和幼苗库,60%的物种具有植冠种子库;除一年生植物,其他植物均可进行营养繁殖,表明潜在的抗侵蚀植物均能维持自身的生存繁衍。5)42种植物中有13种为主杆型植物,其较大的冠幅能够保护基部土壤;8种疏丛型植物具较强的保护土体和拦截沉积物能力;6种聚丛型和7种簇丛型植物能有效拦截沉积物。总之,只占研究区记录的总物种数13%的潜在抗侵蚀植物具有种子库和幼苗库,多年生植物以营养生殖为主,能维持自身的生存繁衍;由于植冠对其下土壤的保护和植物基部茎对沉积物的拦截,在植物基部能形成土堆,可有效控制土壤侵蚀。

Potential erosion-resistant species analysis in the hill-gully region of the Loess Plateau

The Loess Plateau is well known for its severe soil erosion. Soil erosion severely interferes with the process of plant development and succession. However, plants do survive in this region of very serious soil erosion. These individuals can overcome stress and disturbance due to soil erosion through various breeding strategies, as well as through morphological and physiological compensation. Therefore, a plant is considered erosion-resistant when it not only has survived and adapted to the soil erosion environment, but it can also protect and improve the soil, prevent further soil erosion, regenerate itself, and maintain the plant community''s stability and sustainable development. This study was based on several years (2003-2014) of vegetation survey data of the Yan river basin in the hill-gully region of the Loess Plateau. The research objective was to select potential erosion-resistant species, and subsequently illustrate their distribution characteristics and their survival and propagation ability. The definition of erosion-resistant species and Braun-Blanquet phytosociology methods were used to select potential erosion-resistant species. The main results were as follows:1) A total of 42 potential erosion-resistant species were selected, which belong to 18 families and 33 genera. Gramineae, Leguminosae, Compositae, and Rosaceae species accounted for 66% of the total potential erosion-resistant species. 2) Phanerophyte, chamaephytes, and hemicryptophytes were the main plant life forms, and they accounted for 85% of the total erosion-resistant species. Shrubs or small shrubs, and perennial herbs were the main plant growth forms, and they accounted for 76% of the total erosion-resistant species. Xerophyte and mesophyte plants were the main plant water ecological types, accounting for 78% of the total erosion-resistant species. Furthermore, combined with the climatic conditions of study area, the 42 potential erosion-resistant species could be divided into three types:eurytopic species, medium amplitude species, and stenotic species. 3) Overall, 55% of the species were erosion-resistant, having a maximum cover over 50%, and could be the structural or single dominant species in a community. Maximum cover of the other species was less than 50%, and these species usually were the co-dominant species. All potential erosion-resistant species had a high cover and aboveground biomass, indicating that these species could adapt to different erosion environments and grow adequately. 4) Almost all 42 potential erosion-resistant species had a soil seed bank and seedling emergence, and 60% erosion-resistant species had canopy seed bank. Except for annual plants, allspecies were able to reproduce asexually. This result indicated that the potential erosion-resistant species could maintain their own survival and reproduction. 5) From the 42 potential erosion-resistant species, 13 had a basal stem-shoot architecture, with a large crown that can protect the base soil. Furthermore, eight species have an expanding shoot architecture, which display a strong ability to protect the soil and intercept sediments. In addition, six species have dense shoot architecture, and seven have a tussock-forming shoot architecture. Both types can effectively intercept sediments. In conclusion, the potential erosion-resistant species, which only occupied 13% of the total species recorded, had a seed and seedling bank. Furthermore, the perennial plants mainly employed vegetative reproduction, and could maintain their own survival and reproduction. Because the plant crowns can protect the soil surface and plant base stems can intercept sediments, a mound can be formed in the plant base, which will effectively control soil erosion.