| ISSR (inter-simple sequence repeat) molecular marker was used to investigate the genetic diversity variation of Stipa aliena and Elymus nutans populations under the disturbances of warming and grazing in Haibei national field research station of alpine grassland ecosystem located in Qinghai province, in China. The results are followed:1. Stipa aliena populations and Elymus nutans populations have higher genetic diversity, which were much higer than them of higher plants. Total percentage of polymorphic bank (PPB) of Stipa aliena populations was higher than that of Elymus nutans. For Stipa aliena populations, at population level, PPB, Nei’s gene diversity(H*) and Shannon information index(I*)were89.61%,0.1978and0.3035, respectively; at individual level, it is respectively98.61%,0.2357,0.3692. For Elymus nutans populations,74.82%,0.1603,0.2438at population level; and92.86%,0.2418,0.3759at individual level.2. The genetic differentiation mianly generated interpoplation for Stipa aliena populations and Elymus nutans populations.3. The response of genetic diversity of Stipa aliena populations to grazing was significant. It also shows that warming can decrease the populations’genetic diversity.4. For Elymus nutans populations, the response of the genetic diversity to warming and grazing were not significant. However there was a trend that the two disturbances reduced genetic diversity of two populations. We found that the effects of warming were greater than grazing factor.5. Short-time scale of disturbances (warming and grazing) affected the genetic diversity of the two species in a certain extent. But the responses of the genetic diversity to two disturbances were different for Stipa aliena and Elymus nutans populations. Stipa aliena was sensitive to grazing, but the other one was sensitive to warming. For the complex experiments (warming and grazing), the genetic diversity of (W-G) was lower than the control for Elymus nutans populations, but Elymus nutans populations was higer. |
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