Ecosystem land cover and vegetation trends under climate change in the low stream of the Amu Darya River watershed

Abstract

The Amudarya Delta (N42°36’ E59°28’) is a showcase for a wetland complex lying downstream in a transboundary river basin from the northwestern part of the Kyzylkum, the Zaunguz Karakum (the territories adjacent to the Uzboi), Ustyurt, the valley and delta of the lower reaches of the Amu Darya River, bordering to the Aral Sea. The area represents a downstream conflict over water competition between water users: irrigated agriculture and natural ecosystems. Due to climate change and water shortage, the Amudarya Delta watershed zone faces the challenges associated with soil salinity, rising water table, and loss of agrobiodiversity and food insecurity. Ecosystem-based land use and conservation are recognized to be among the most severe natural resource degradation factors. Salt affected irrigated lands in the Amydarya Delta (Karakalpakstan, Khoresm regions, and some territories in the northern part of Turkmenistan) increased at average from 1,16 mln. ha in 1990 to 4,43 mln ha (more than 80%) in 2017. Access to irrigation water in this region has drastically decreased in the last decades, which caused additional obstacles to agricultural production, especially grazing capacity of natural pastures. The hot spots of degraded pasturelands due to low species richness and botanic diversity occurred on the Artemisia foothill-plains transects along the Lower Amu Darya Biosphere Reserve (LABR) near the settlements Beruni, Mangit, Nazarkan towards Khoresm and Northern Turkmenistan.

This study is focused on Land Use/Land Cover (LULC), vegetation/plant communities, and agrobiodiversity trends under climatic variables for the period 2011-2018. Tugai-forest and wetlands category, which frequently occurred at LABR is under serious threat now. The vegetation composition is also rich in edible species and thus, this type of vegetation can be used during the year, but local pastoralists prefer to have it in the winter season since tugay forest can stand as a good shelter for livestock against cold weather. Channels overgrow with aquatic vegetation, which leads to their rapid shallowing because of the large halophytes forming dense thickets. They play the role of a filter and precipitate suspended particles at the collectors’ bottom, which contributes to the rapid shallowing of the network. Overgrowing and silting often lead to the fact that saline water enters the fields and salinizes them repeatedly. Scenarios for sustainable water and land-use practices are suggested.