侵蚀环境退耕撂荒地植物种群演变动态研究

以侵蚀环境不同年限的撂荒地为研究对象,研究撂荒后植物种群生态结构演变过程,结果表明,退耕撂荒后植被演替恢复过程可划分为:先锋植物物种期(1~5 a),物种渐繁荣期(6~8 a),物种鼎盛期(9~13a),物种准稳定期(13~20 a)、物种相对稳定期(20~30 a)和灌木先锋物种入侵期(30~50 a)。其中先锋植物物种期以茵陈蒿、苦买菜、猪毛菜为关键种;物种渐繁荣期以委陵菜、阿尔泰狗哇花和隐子草为关键种;物种鼎盛期多物种共存,关键种不明显;物种准稳定期以长芒草、铁杆蒿和达乌里胡枝子为关键种;物种相对稳定期以铁杆蒿、达乌里胡枝子为关键种;灌木先锋物种主要有杠柳、木本铁线莲、绣线菊等。在植被恢复过程中,先锋植物物种在演替初期先增多,而后逐渐减少,到演替中后期时演变为偶见种或从群落中基本消失;而一些过渡指示物种,其地上生物量大多呈升——降的变化趋势;群落稳定优势种的地上生物量呈持续增大的演变趋势,它们在群落中的重要性也是越来越大。而演替中的过渡优势种的地上生物量的演变趋势为单峰曲线,它们在群落中的重要性同样经历了一个由升到降的演变过程。同时,退耕撂荒地植被演替中,大多数先锋植物的生态位宽度较窄,分布范围较小,是生态特化种;但优势先锋植物,生态位宽度却较大,分布范围极广,是生态泛化种。与之相对应的演替中后期过渡优势种或稳定优势种,生态位宽度则较窄,分布范围不及优势先锋植物,是生态相对泛化种。退耕撂荒地植被演替中植物种群的替代是通过物种的生态适应性和种间竞争来实现的。

Dynamic of Plant Population Characteristics on Abandoned Arable Land in Eroded Hilly Loess Plateau

In order to understand the evolution of plant population characteristics in loess hilly area of the Loess Plateau,11 arable old land with different ages after being abandoned were studied systematically through the approach of substituting the temporal serial with spatial serial.The results showed that during the process of vegetation restoration on the land abandonment,the succession course can be divided into six phrases: the pioneer species period(1 ~ 5 a),the species gradually prosperity period(6~ 8 a),the species prime period(9 ~ 13 a),the species quasi-steady period(13 ~ 20 a),the species relatively steady period(20 ~ 30 a) and the bush pioneer species invasion period(30~50 a).The key species in the pioneer species period is Achillea capillaries,Ixeris denticulate,Salsola collina.,than the key species gradually change to Potentilla spp,Heteropappus altaicus,Cleistogenes spp in the species gradually prosperity period,Lespedeza dahurica,Stipa bungeana,Artemisia sacrorum in the species quasi-steady period,Lespedeza dahurica,Artemisia sacrorum in the species relatively steady period,Peri ploca sepium Bunge,Clematis fruticosa turcz,Spiraea spp in the bush pioneer species invasion period.The pioneer species increased promptly in early abandoned stage and then gradually decrease and evolve to rare species or vanish during the middle and late period of succession from the comunity.The above-ground biomass of transitional indicative species in the succession process of vegetation restoration bears the changing tendency from rise to fall,on the other hand,the steady dominant species' bears the tendency of continual increase and features greater importance.And the evolution tendency of above-ground biomass of transitional dominant species bears single peak curve,their importance in the community also experiences the changing tendency of rise-fall.In the succession process of vegetation on the land abandonment,most pioneer species are specialization species with narrow niche and small distribution scope;while the dominant species are ecological common species with wide niche and broad distribution scope.In the middle and late period,transitional dominant species or steady dominant species are relative common species with narrow niche and distribution scope inferior to the dominant species.In the succession process of vegetation on the land abandonment,the plant population substitution is realized by the ecology compatibility and the interspecific competition.