摘要
研究了不同放牧强度下 (不放牧、轻牧 (1.33只羊 /hm2 )、中牧 (4.0 0只羊 /hm2 )、重牧 (6 .6 7只羊 /hm2 ) )冷蒿(Artemisiafrigida)、星毛委陵菜 (Potentillaacaulis)的克隆形态 (间隔子长度、分枝强度 )可塑性以及生物量分配格局。两种植物的间隔子长度、分枝强度沿放牧梯度具有显著的可塑性反应。冷蒿间隔子长度 :不放牧 >轻牧 >重牧 >中牧 ;分枝强度 :重牧 >中牧 >轻牧 >不放牧。星毛委陵菜间隔子长度 :轻牧 >不放牧 >中牧 >重牧 ;分枝强度 :重牧 >中牧 >轻牧 >不放牧。冷蒿种群地上现存量随放牧强度增加而减少 ,根茎比随放牧强度增加而增加。星毛委陵菜种群地上现存量随放牧强度的增加而增加 ,根茎比随放牧强度的增加而先减小后增加。形态可塑性和生物量分配格局的差异反映出两种植物对不同放牧强度有不同的生态适应对策 ,星毛委陵菜比冷蒿更能适应高强度的放牧。
In order to understand the degradation process and its mechanism on Inner Mongolia Typical Steppe, clonal morphological plasticity and biomass allocation patterns of two dominant species, Artemisia frigida and Potentilla acaulis were studied under different grazing intensities(no grazing,light grazing: 1.33 sheep·hm -2 ,moderate grazing: 4.00 sheep·hm -2 ,heavy grazing: 6.67 sheep·hm -2 . The research was conducted at the Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences(43°26′_44°08′ N, 116°04′_117°05′ E).The results showed that spacer length and branching intensity of these two species responded to grazing intensities significantly. From no grazing to heavy grazing, spacer length of A. frigida was 0.75, 0.65, 0.54 cm and 0.59 cm respectively. That of P. acaulis was 3.03, 3.44, 2.97 cm and 2.53 cm respectively. Branching intensities increased with the increase of grazing intensities, which were 2058, 2325, 2768, 2901 ind.·m -2 for A. frigida and 832, 896, 971, 1162 ind.·m -2 for P. acaulis . Plasticity in the resource allocation patterns of plants under different growing conditions is adaptive, and reflects a tendency toward optimization of performance in any environment. ANOVA results showed significant effects of grazing treatments on population total biomass, above_ground biomass and R/S ratio. Population total biomass in A. frigida decreased while that in P. acaulis first decreased and then increased with the increase of grazing intensities. The above_ground biomass in A. frigida fell significantly with the increase of grazing intensities. The reverse trend was true for P. acaulis . Trends in R/S were similar to those in above_ground biomass. The biomass allocation pattern of A. frigida was: roots > leaves >stems. ANOVA results did not show significant effects of grazing treatments on biomass of leaves, roots and their allocation in A. frigida except stems and its allocation. The differences in stem biomass and its allocation were significant between no grazing and light grazing, light and heavy grazing. Biomass allocation pattern of P. acaulis was: roots > leaves > stolons > petioles. ANOVA results showed significant effects of treatments on biomass of leaves, stolons and roots and their allocation except for petioles in P. acaulis . The difference in biomass allocation to roots was significant between no grazing and other grazing treatments. There was significant difference in biomass allocation to leaves between no grazing and light grazing, light and heavy grazing. In order to occupy more space and resources, biomass allocation to stolons increased with the increase of grazing intensities. Differences in morphological plasticity and biomass allocation patterns of these two species indicated that they had different ecological strategies to grazing. P. acaulis was more adaptive to heavy grazing than A. frigida . Communities of Leymus chinensis and Stipa grandis may finally converge to P. acaulis communities under continuous over_grazing and then desertify.
出处
《植物生态学报》
CAS
CSCD
北大核心
2002年第4期435-440,共6页
Chinese Journal of Plant Ecology
基金
国家重点基础研究发展规划项目 (No.G19990 4340 7)
中国科学院知识创新项目 (KSCX2_1_0 7)和 (KSCX_1_0 8)
关键词
放牧强度
冷蒿
星毛委陵菜
形态可塑性
生物量分配格局
生态适应
资源分配
草地
Ecological adaptation, Grazing intensity, A. frigida and P. acaulis , Clonal morphological plasticity, Biomass allocation
