Application of LFA method to quantitative monitoring and assessment of vegetation degradation in mining area of eastern Shanxi

The evaluation of vegetation degradation monitoring and vegetation restoration in the coal exploration area was rarely conducted from the perspective of landscape. However, researches on the coal exploration area at landscape scale will be helpful to understand the spatial distribution pattern of vegetation. In this study, we took eastern Shanxi (Yangquan Nanzhuang coal) coal mining areas as the interference sources, and set up six equidistant lines with the distance of 800, 1500, 2100, 2800, 3500 and 4200m according to the quadrant sampling. Meantime, five sample lines with each length of 100m were deployed along the direction perpendicular to the contour by using LFA (Landscape Function Analysis) method. The patch area index and landscape structure index were calculated by measuring patch quantity, patch width per unit length and average distance and size between patches per unit length. The surface soil health was evaluated around the sample lines. The evaluation index involved four vegetation indexes, i.e., surface coverage (rainfall erosion protection), perennial vegetation coverage, litterfall status and cryptogam vegetation coverage, and seven indicators of soil physical and chemical properties, i.e., degree of soil erosion, soil sediment, surface soil roughness, surface soil characteristics, soil collapse coefficient and soil texture. The purpose of the study was to reveal the distance which coal mining affected local landscape structure and function and its mechanism. The results showed that the effect of coal mining on soil total porosity and soil saturated water content weakened along the increase of distance from the coal mining area. This induced index of soil stability, soil permeability and nutrient cycling to rise accordingly. With the increase of distance from the coal mining area, each indicator related with LFA presented the trend of slow increase to rapid increase and to a stable level. Landscape function developed towards in favor of water and nutrient conservation. When the intensity of coal mining was 3.2 million tons/year, nature reserve and city planning and construction should guarantee the minimum ecological safety distance of 4370m.