Monitoring on vitality dynamics of tugai vegetation in the lower reaches of Tarim River by ecological water delivery

The Tarim River is about 1 320 km long and thus one of the longest continental inland waterways worldwide. The rising water consumption in the upper and middle reaches and massive hydrotechnical interventions during the development of uncultivated land use (cotton growing) in the past decades,led to the widespread destruction of the natural ecosystems,particularly in the lower reaches of the river where on 320 km the floodplain forests of Euphrat poplars (Populus euphratica Oliv.) are either highly degraded or dead. Since 2000 the Chinese government has made efforts to restore these ecosystems and conducted ecological water delivery. According to monitoring results after the ecological water delivery in the past five years,the paper analyses the vitality dynamics of the Tugai vegetation in the lower reaches of the Tarim River. The results show:Due to ecological water delivery,there are a lot of changes. The biological diversity in the lower reaches of theTarim River has increased,a lot of plants that disappeared for a long time have reappeared,and the P. euphratica community has regenerated naturally to different degrees. Within 50 metres from the river course,a few P. euphratica and Tamarix spp. seedlings appear. Within 150 metres from the river course,a considerable number of P. euphratica appeared. Within 400 metres from the river bank,approximately 25% of P. euphratica have formed new branches at the base after the ecological water delivery. With water levels gradually rising after the water delivery,non-zonal meadow vegetation has developed in the large areas of the low-level terraces on both sides of the river sparse Arid non-zonal riparian vegetation commu-nities composed of P. euphratica,shrubs and herbaceous plants (Tugai Vegetation) developed,showing that ecological emergency water delivery has had a positive impact on vegetation vitality restoration and natural recovery of desert riparian vegetation whose main species is P. euphratica.