不同灌溉量对退化草地的生态恢复作用

Ecological restoration of the deteriorated grassland with different irrigation volumes

在希拉穆仁草原进行了为期3年的草地灌溉试验,对测试的试验地在灌溉3年期间及停灌后1年内进行了植被调查和土壤种子库发芽试验,结果表明:一是灌溉可以明显提高草地植被的生产性能且不同灌溉量间并无明显差异。当停止灌溉后,原灌溉样地的植被生产性能均略低于无灌溉对照区,且不同灌溉量间也无明显差异。二是不同灌溉量样地植被物种组成与无灌溉对照区的Bray-curtis相似性系数始终保持在0.8左右,表明灌溉期间群落结构并未发生很大变化。当停止灌溉后,原灌溉样地与无灌溉对照区的Bray-curtis相似性系数下降为充足灌溉区0.61和中度灌溉区0.55,表明灌溉对植物的生存策略有一定的影响且不同灌溉量基本相同。三是土壤中的种子总数量有所增加,但物种的数量有所减少。充足灌溉样地土壤种子库情况略差于无灌溉对照区,中度灌溉样地则略好于无灌溉对照区,表明不同灌溉量对植物的繁殖策略有一定的影响。

The grassland irrigation tests have been carried out for 3 years in Xilamuren Grassland, including the vegetation investigation and germination test of soil seed bank of the tested land during the three years with irrigation and one year without irrigation. Results show that, first, irrigation can remarkably improve the productive performance of grassland vegetative cover without obvious difference between the different irrigation volumes. After the irrigation was stopped, the productive performance of grassland vegetative cover of the original irrigated sample plot was a bit lower than non-irrigated check plot, and there was no obvious difference between the plots with different irrigation volumes. Second, for vegetation species composition, the Bray-curtis similarity coefficient between the original irrigated sample plot and the non-irrigated check plot was always around 0.8, showing that there was no big change of community structure during irrigation period. After the irrigation was stopped, the Bray-curtis similarity coefficient between the original irrigated sample plot and the non- irrigated check plot decreased, with the adequately irrigated plots standing at 0.61 and the moderately irrigated plots standing at 0.55. This means that, irrigation would affect the living strategy of plant regardless of irrigation volumes. Third, the total amount of seed in soil increased a bit, however the number of species decreased. The situation of soil seed bank in adequately irrigated plot was a little worse than the non-irrigated check area, moderately irrigated area was a bit better than the non-irrigated check area. This means, the different irrigation volume will have certain impact on the reproduction stratagem of plant.