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    LFA方法在晋东采煤区景观结构及功能评价中的应用

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

    • 摘要: 煤炭开采区植被退化监测和植被恢复的效果评价较少从景观角度进行,然而对开采区进行景观尺度的研究,有助于了解植被的空间分布规律。本文以晋东(阳泉南庄煤矿)采煤作业区为干扰源,按照扇形取样,依距离设置800、1500、2100、2800、3500和4200m 6条等距线。采用LFA方法,沿垂直于等高线的方向,布设5条长度为100m的样线,通过对斑块数量、单位长度上斑块宽度、单位长度上斑块间平均距离和大小的测量,计算斑块面积指数和景观结构指数;对样线周围土壤进行地表土壤健康评价,评价指标包括地表盖度(降雨溅蚀保护)、多年生植被覆盖度、枯落物状况、隐花植被盖度4项植被层指标以及结皮破碎性、土壤侵蚀程度、沉积物、地表粗糙度、地表特征、土壤崩解系数、土壤质地7项土壤理化性质指标。通过研究揭示煤炭开采对当地景观结构与功能的影响距离及机理。结果表明:随着距煤炭开采区距离的增加,煤炭开采对土壤总孔隙度、土壤饱和含水量的影响削弱,进而造成了土壤稳定性指数、土壤渗透性指数、养分循环指数的同步上升。随着距离的增加,LFA相关的各项指标均呈现由慢速增加至快速增加再到逐步维持的趋势。景观功能向着有利于水分、养分保蓄的方向发展。当煤炭开采强度为320万t/a时,自然保护区及城市规划建设应保证最小生态安全距离为4370m。

       

      Abstract: 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.

       

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