德州市生态环境质量指标时空变化特征

The Spatio-Temporal Variation Characteristics of Eco-Environmental Quality Indicators in Dezhou City

摘要: 归一化植被指数是生态质量评价中的一项重要遥感指标，能够直接反映植被的密度、叶面积指数光合作用强度，是衡量生态系统初级生产力和植被健康状况的关键参数。本文利用美国航天局提供的MODIS NDVI数据，通过最大化合成法、逐像元线性回归分析法和皮尔逊相关系数对德州市NDVI动态变化进行分析，结果表明：(1) 德州市NDVI总体呈波动下降趋势，2010年减速显著提升，2015年剧烈波动下降至0.4405，植被覆盖状况逐步恶化。(2) 年均降水量年际波动剧烈，年均气温变化总体平稳，年均温为14.1℃。NDVI与降水量变化趋势大致相同，与气温变化趋势大致相反。(3) NDVI均值处于0.17~0.60之间，整体呈现中部高于东西部的特征。德州市大部分地区NDVI变化呈现上升的趋势，呈现下降趋势的地区主要分布在德城区。植被覆盖度改善、退化的程度并不明显。(4) NDVI与降水的相关性整体略高于气温，NDVI与降水量的相关性变化范围为−0.5874~0.4277，与气温为−0.7801~0.8275。除降水影响外，植被生长对农田灌溉具有一定的依赖性。德州市植被覆盖变化受水热条件的共同调控，但降水因子的贡献更为突出。

Abstract: The Normalized Difference Vegetation Index (NDVI) is a crucial remote sensing indicator in ecological quality assessment. It directly reflects vegetation density, leaf area index, and photosynthetic intensity, serving as a key parameter for evaluating ecosystem primary productivity and vegetation health status. This study utilizes MODIS NDVI data provided by NASA to analyze the dynamic changes of NDVI in Dezhou City through methods including maximum-value compositing, pixel-wise linear regression analysis, and Pearson correlation coefficient. The results indicate that: (1) The overall trend of the ecological quality indicator NDVI in Dezhou City shows a fluctuating decline. A significant deceleration in the decline rate was observed in 2010, followed by a sharp fluctuating drop to 0.4405 in 2015, indicating a gradual deterioration in vegetation cover conditions. (2) Annual precipitation exhibits substantial interannual variability, while mean annual temperature remains relatively stable, with an average of 14.1˚C. The variation trend of NDVI generally aligns with that of precipitation but shows an opposite trend compared to temperature. (3) The mean NDVI values range between 0.17 and 0.60, exhibiting an overall spatial pattern where the central region has higher NDVI values than the eastern and western parts. Most areas in Dezhou City show an increasing trend in NDVI, whereas areas with decreasing trends are mainly concentrated in Decheng District. The degree of improvement or degradation in vegetation coverage is not pronounced. (4) The correlation between NDVI and precipitation is generally slightly higher than that with temperature. The range of correlation coefficients between NDVI and precipitation is −0.5874 to 0.4277, while that with temperature ranges from −0.7801 to 0.8275. In addition to precipitation, vegetation growth also relies to some extent on farmland irrigation. Vegetation cover changes in Dezhou City are jointly regulated by hydrothermal conditions, but the contribution of the precipitation factor is more prominent.