基于MODIS数据的近20年海南岛叶面积指数时空变化及驱动力分析

Analysis of spatio-temporal variation and driving forces of leaf area index in Hainan Island over the last 20 years based on MODIS data

  • 摘要: 叶面积指数(LAI)是重要的植被结构参数之一, 在监测植被生长状态、评估生态系统健康以及制定环境保护政策等方面均具有重要价值。海南岛因其特殊的地理位置和气候条件, 拥有丰富的植被资源, 气候变化及人类活动对其影响不断加剧。因此, 深入研究海南岛LAI的时空变化对于理解该地区植被状况具有重要参考意义。本研究基于2002—2022年的MOD15A2 LAI产品数据集和气象数据, 利用Theil-Sen中值分析和Mann-Kendall趋势检验等方法, 分析了海南岛LAI的时空分布变化及其对气候因子的响应。结果表明: 1) 2002—2022年, 海南岛LAI整体呈增长趋势, 其中北部的增长趋势明显强于南部。这一现象与橡胶种植业的发展和南部地区旅游产业的兴起有关, 表明LAI的变化与人类活动紧密相连。此外, 海南岛的LAI分布呈现中部高、周边低的空间特征, 与该地区的地势特征相一致。2) 2002—2022年海南岛LAI的平均变异系数为0.136, 说明植被变化波动较小, 表明其能保持生态平衡和一致性。3)在气候暖干化的背景下, 温度上升对植被生长的促进作用存在饱和效应。海南岛北部地区的LAI与温度主要呈正相关, 而南部地区主要呈负相关, 降水的影响则与温度相反。以上结果表明, 海南岛LAI的空间差异和时空变化主要受气候条件、地形和人类活动等多种因素的协同作用。本研究为海南岛植被保护、生态修复和气候适应性管理提供了科学依据。

     

    Abstract: Leaf area index (LAI) is a critical indicator of vegetation structure, essential for monitoring vegetation growth, assessing ecosystem health, and guiding environmental protection strategies. Hainan Island, renowned for its unique geography and climate, experiences significant impacts from climate change and human activities, influencing its abundant vegetation resources. Therefore, understanding the spatio-temporal dynamics of LAI on Hainan Island is crucial. Using the MOD15A2 LAI product dataset and meteorological data from 2002 to 2022, we employed Theil-Sen median analysis and Mann-Kendall trend tests to analyze LAI trends and assess climatic influences. We found that: 1) From 2002 to 2022, LAI has generally increased across Hainan Island, with a more pronounced trend in the northern regions compared to the south. This trend correlates with the expansion of the rubber industry in the north and the development of tourism in the south, highlighting the significant impact of human activities on LAI. Additionally, LAI tends to be higher in central areas and lower in peripheral regions, consistent with spatial variation of topography. 2) The average coefficient of variation (CV) for LAI over the last 20 years was 0.136, indicating minimal fluctuations in vegetation dynamics and ecological stability of the island. 3) Under the background of a warming and drying climate, we observed a saturation effect in vegetation growth response to increasing temperatures: LAI in most northern regions positively correlates with increasing temperature, while most southern regions show a negative correlation. Precipitation exhibits opposite effects, influencing temperature gradients. These results underscore the complex interplay of climate, topography, and human activities as primary drivers of spatial and temporal variations in LAI on Hainan Island. This study provides a scientific foundation for enhancing vegetation protection, promoting ecological restoration, and implementing climate-resilient management strategies across the island.

     

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