Natural and Anthropogenic Dynamics of Vegetation in the Aral Sea Coast

Abstract

Natural dynamics (primary successions) is studied in the dry seabed of the Aral Sea. Long-term studies of vegetation have identified three types of primary successions: psammosere, halosere and potamosere (sere of shrubby riparian vegetation). They differ by soil texture and salinity, patterns of temporal dynamics, and stages, selected on a basis of ecological-physiognomic features of dominant plants. Late seral stages were identified for succession types: psammophytic shrub (Calligonum spp, Astragalus brachypus, etc.) for psammosere; haloxerophytic and xerophytic dwarf semishrubs (Anabasis salsa, Artemisia pauciflora, A. terrae-albae) for halosere. There is a change of a dominant plant and succession dynamics in late seral stages in potamosere (Tamarix spp. → Calligonum spp, Haloxylon aphyllum, Artemisia terrae-albae). Anthropogenic dynamics of vegetation (secondary successions) depends on factors of disturbance. There is a set of anthropogenic factors causing degradation of vegetation cover: (1) agricultural: overgrazing, haymaking, plowing, clearing trees and shrubs; (2) linear structures (paved and dirt roads); (3) water management: construction and operation of hydraulic structures, fluctuation in river runoff and the sea level, disturbance in the natural flooding regime; (4) fires; (5) recreations. The leading factors in the region are connected with water management and irrigation. To identify the dynamics of plant communities and potential degradation trends, there are series of shifts (successional series): hydro-, xero-, halo-, psammo-seres characterizing moisture content and edaphic environments. Changes in the hydrologic regime of the Syrdarya river, building of the hydraulic structures lead to reduction of hydromorphic vegetation and a change it into halophytic desert. The construction of the Kokaral dam and restoration of the Small Aral Sea has led to the rehabilitation of wetlands and plant diversity. Hydrogenous succession facilitated a gradual recovery of populations of rare species listed in the Red Data Book of Kazakhstan, IUCN, Europe (Scirpus kasachstanicus, Nymphoides peltatum, Salvinia natans, Typha minima).

Changes in the Biomass of Vegetation in the Aral Sea Region

“…Despite the drying of the sea 50 years ago, as the main guiding force, the primary and intermediate stages of the haloserium succession with the dominance of annual saltpans and the halophilic shrub fraction remain unchanged. According to L. Dimeyeva (2015), the haloserium lasts for 30-40 years and gives way to the psammoserium. However, the psammoserium rate dominates only in local areas of the Muinak Peninsula and the adjacent western and southern territories of the Renaissance Island.…”

Combining Multiple Plant Attributes to Reveal Differences in Community Structure in Two Distant Deserts in Central Asia

“…The dynamics of plant communities appear with a series of shifts (successional series)—potamo-, xero-, halo-, and psammosere—characterizing the moisture content and edaphic environments. Therefore, for plant community change, water is the primary limiting factor [ 55 ]. For almost all attribute matrices in the present study, the main factors influencing community structure were longitude, climate (MAP, MAT, DSR, and VDP), and soil (SWC, MAST, TN, TP, TK, and TS).…”

Reviving the Aral Sea: A Hydro‐Eco‐Social Perspective

“…Furthermore, the NDVI of vegetation in the exposed lakebed of the Aral Sea along with its salt and sand dust are directly associated with the lake level (Figures 2c and 2d). Since the lake began retreating in the 1960s, plant species have colonized the bare surface (Figure S2 in Supporting Information S1), and vegetation communities are now established, in a process shaped by local conditions tied to precipitation, groundwater, and soil salinity (Dimeyeva, 2007(Dimeyeva, , 2015Duan et al, 2022). Lake level restoration efforts since 2006 have increased the vegetation status, as evidenced in higher NDVI values near the shoreline of the North Aral Sea (Figure 2c) and the particularly rapid increase since 2015, peaking at 0.08 in 2020 in the exposed area (Figure 3a).…”