[Influence of Land Use Change on Ecosystem Service Value Based on GEE in the Beijing-Tianjin-Hebei Region from 1998 to 2018].

In sustainable development assessment of the Beijing-Tianjin-Hebei region, the ability to dynamically estimate the value of ecosystem services is of great significance. This study considers the Beijing-Tianjin-Hebei region as the research area, based on the google earth engine (GEE); the classification and decision tree (CART) classification algorithm was adopted to supervise and classify the Landsat Thematic Mapper/Operational Land Imager (TM/OLI) images in the study area in 1998, 2003, 2008, 2013, and 2018, and land use types in these five periods were obtained. Quantitative analysis of the dynamic changes of land use in the Beijing-Tianjin-Hebei region from 1998 to 2018 was carried out. Then, the ecosystem service value (ESV) equivalent estimation method was used to quantitatively estimate the ESV in the Beijing-Tianjin-Hebei region and combine it with a 15 km×15 km scale grid to detect its temporal and spatial dynamics. The main results were as follows. ① From 1998 to 2018, the area of construction land (increased by 16.67%) and grassland (reduced by 13.73%) in the six land use types in the Beijing-Tianjin-Hebei region was the largest, and the change in the proportion of water bodies (0.2%) was the smallest. ② The total value of ESV in the Beijing-Tianjin-Hebei region experienced a short-term increase from 1998 to 2003 (an increase of 91.97×108 yuan), and continued to decrease from 2003 to 2018 (a decrease of 239.07×108 yuan), mainly related to the expansion of construction land area in the other three time periods excluding 1998 and 2003. Among the six land use types, the forest provides the highest value of ecosystem services, and the construction land and unused land provide the lowest value of ecosystem services. ③ The ESV time-space analysis based on the 15 km×15 km scale grid showed that the ESV medium area in the Beijing-Tianjin-Hebei region gradually decreased from 1998 to 2018, the ESV lower area and the higher area gradually increased, and the ESV lower-area growth rate was higher than for the higher area. ④ The revised value of the Beijing-Tianjin-Hebei region (sensitivity coefficient range 0-0.83) has good significance and reliability. In future economic development, the Beijing-Tianjin-Hebei region should rationally optimize the land use pattern and strengthen the protection of forest land, grassland, water bodies and cultivated land.

Study on method for assessment of the physical structure integrity in Chagan lake in China based on remote sensing.

This paper, taking Chagan lake as the study area, uses and improves MWR V1.0 (Rivers (Lake) Health Assessment Indicators, Standards and Methods V1.0) relating to the theory and method of physical structure integrity assessment. A 500 m × 1000 m grid on the lakeshore zone is a basic evaluation unit, and then a lakeshore physical structural integrity evaluation system using remote sensing (RS) and geographic information system (GIS) technology is established, which contains a target layer, criterion layer and indicator layer. The criterion layer consists of lakeshore condition, shoreline development rate and lake atrophy rate, and the index layer is composed of slope, vegetation cover rate and water level change rate, and another eight indicators. The results showed that for the 23 monitoring points in Chagan lake and the 15 monitoring points in Xinmiao lake, the evaluation results based on RS were 0.60-0.74 and 0.35-0.52, respectively, and the field evaluation results were 0.64-0.77 and 0.35-0.55, respectively. The evaluation results of the two methods consistently indicated that the physical structure of the lakeshore of Chagan lake was healthy and the Xinmiao's lakeshore was sub-health. On this basis, a piecewise evaluation method of physical structure integrity based on the division of the nature reserve function was proposed in this paper.