松嫩草地不同次生光碱斑种子流比较及其潜在生态恢复意义

在松嫩平原不同退化程度的草地中选取三个次生光碱斑,通过分析其土壤种子库和表面种子流动态,探讨了土壤表面种子流在次生光碱斑植被恢复中的潜在作用。研究结果表明:样地间种子流种类与数量上相似性很高,且种子流与周围植被具有一定的相关性。土壤表面种子流数量巨大,且以一年生耐盐碱的先锋植物(虎尾草和碱蓬)种子为主,占总流量的 96 %。虽然土壤表面的种子流量巨大,但次生光碱斑对种子的截留能力很低,土壤种子库得不到及时更新与补充,常处于较低水平,尤其在 5 月份和 6 月份,土壤中甚至没有种子出现。土壤种子库和表面种子流表现出季节性动态变化,均在 10 月份达到最大。土壤种子库缺乏是限制次生光碱斑的植被自然恢复能力的一个重要因素。因此,表面种子流是潜在的种子资源,提高次生光碱斑对种子的截留能力(人工处理方式),将加速次生光碱斑的植被恢复进程。图 5 表2 参 27。

Seed movement of bare alkali-saline patches and their potential role in the ecological restoration in Songnen grassland, China

The dynamics of soil seed banks and seed movement was investigated in three bare alkali-saline patches in Songnen grassland, Northeast China, for exploring their potential role in the vegetation restoration of bare alkali-saline patches. The results showed that the seed banks and the seed movement in these patches were very similar to each other, and to some extent the seed movement was related to patch-side vegetation there. Seed movement across the soil surface of these bare alkali-saline patches was abundant and dominated by the seeds of pioneer species, such as Chloris virgata and Suaeda corniculata, which accounted for over 96% of these trapped seeds. In the contrast, soil seed banks of bare patches were extremely small, in different seasons, especially in May and June, even no any seed have been found, mainly due to lowest retaining capacity of surface soil to those abundant seed movement. Both soil seed banks and seed movement showed seasonal variation, and usually reached the maximum in October. Soil seed banks of bare alkali-saline patches, which were extremely small and difficult to recruit naturally, may inhibit speed of vegetation restoration. It is suggested that seed movement would be the potential seed source and play a potentially important role in the process of vegetation restoration of bare alkali-saline patches by enhancing the soft retaining capacity to seed movement.