Spatio-Temporal Evolution of the Ecological Environment in a Typical Semi-Arid Region of Northeast China

Abstract

Increasing trends of groundwater and soil salinization, as well as desertification, is characteristic of many arid and semi-arid regions under climatic and anthropogenic influences. This has led to the implementation of management strategies to protect the ecological environment. Changling County in Northeast China is a typical semi-arid area that has experienced these changes. Thus, management strategies such as the “Three North Shelterbelt Project” which involves planting trees to reduce wind speed and halt desertification, and the Changling local alkaline land restoration project, from the year 2000, involving fencing of grasslands have been implemented in the area. Premised on the dynamic nature of the ecological environmental problems, this study was undertaken to assess the spatio-temporal evolution of the ecological environment using hydro-geochemical, spatial, remote sensing, and statistical techniques from the year 2001 to 2019. It was found that groundwater salinity was stable within the period due to groundwater exploitation that declined depth to groundwater table (DWT) thus reducing the impact of evaporation concentration of salts in groundwater. Salinized land area increased by about 6706 ha at a rate of 0.06%/year as a result of the reduction in the size of water bodies and swampland as the declining water table exposed shallow water to more evaporation. The effect of the conversion of water bodies and swamplands to salinized land is believed to overshadow the climatic influence of decreased evaporation-precipitation ratio that normally decreases soil salinization. Most of the study area was stable in terms of desertification (98.22%, 56,3497 ha) as significantly degraded lands covered only 0.03% (148 ha) of the area while 1.67% (9556 ha) had significantly increased vegetation, respectively. Precipitation had an insignificant relationship with desertification with irrigation believed to be the main driver of significant vegetation improvement. Water-saving irrigation practices and the growing of salt-tolerant or semi-tolerant crop species are recommended to maximize food production while stemming the environmental degradation trend due to declining DWT.