Effects of landscape conservation on the ecohydrological and water quality functions and services and their driving factors

Since the implementation of landscape conservation of the green heart area in the Changsha-Zhuzhou-Xiangtan Metropolitan Region, the landscape structure and pattern have changed significantly. The ecosystem service functions in the area have been improved, but the status of ecohydrological and water quality and service functions (EHWQSFs) is still unclear. To clarify the status of EHWQSFs and their driving factors influenced by landscape conservation, this study analysed landscape changes using remote sensing image data from 1998, 2008, and 2018 and the changes and their spatial characteristics using the Soil and Water Assessment Tool (SWAT) and spatial analysis methods. The results showed that the dominant land types in the area were forestland and cropland from 1998 to 2018; the area of forestland and construction land expanded and that of cropland decreased year by year; the annual average surface runoff volume rose, and the annual average actual evapotranspiration and soil water content fell from 1998 to 2008 and rose from 2008 to 2018; and all pollutant indicators decreased significantly after 2008. The areas with higher surface runoff were mainly concentrated in the central and southern regions, those with higher evapotranspiration were in the northwestern and southwestern regions, those with higher soil water content were in the northern region, and those with higher sediment and nitrogen and phosphorus pollutant contents were in the central and southeastern regions. The results showed that land use, land cover and meteorological factors were the most significant drivers on EHWQSFs and illustrated that EHWQSFs in the area decreased after 1998. There was a significant improvement after 2008 and the area currently has a good status. This study not only provides insights into land use, land cover and meteorological factors that have significant impacts on EHWQSFs but also highlights that the landscape conservation of the area can improve ecosystem service functions.