Abstract：
The Hawaiian Islands have been identified as a global biodiversity hotspot. We examine the Normalized Difference Vegetation Index (NDVI) using Climate Data Records products (0.05 × 0.05°) to identify significant differences in NDVI between neutral El Niño-Southern Oscillation years (1984, 2019) and significant long-term changes over the entire time series (1982-2019) for the Hawaiian Islands and six land cover classes. Overall, there has been a significant decline in NDVI (i.e., browning) across the Hawaiian Islands from 1982 to 2019 with the islands of Lāna\'i and Hawai\'i experiencing the greatest decreases in NDVI (≥44%). All land cover classes significantly decreased in NDVI for most months, especially during the wet season month of March. Native vegetation cover across all islands also experienced significant declines in NDVI, with the leeward, southwestern side of the island of Hawai\'i experiencing the greatest declines. The long-term trends in the annual total precipitation and annual mean Palmer Drought Severity Index (PDSI) for 1982-2019 on the Hawaiian Islands show significant concurrent declines. Primarily positive correlations between the native ecosystem NDVI and precipitation imply that significant decreases in precipitation may exacerbate the decrease in NDVI of native ecosystems. NDVI-PDSI correlations were primarily negative on the windward side of the islands and positive on the leeward sides, suggesting a higher sensitivity to drought for leeward native ecosystems. Multi-decadal time series and spatially explicit data for native landscapes provide natural resource managers with long-term trends and monthly changes associated with vegetation health and stability.
摘要：
夏威夷群岛已被确定为全球生物多样性热点。我们使用气候数据记录产品（0.05×0.05°）检查归一化植被指数（NDVI），以确定中性厄尔尼诺-南方涛动年份（1984年，2019年）和整个时间序列（1982年至2019年）之间NDVI的显着差异夏威夷群岛和六个土地覆盖类别的序列（1982年至2019年）。总的来说,NDVI显著下降(即，褐变）从1982年到2019年在夏威夷群岛上，拉纳岛和夏威夷岛的NDVI下降幅度最大（≥44％）。在大多数月份，所有土地覆盖等级的NDVI显著下降，尤其是在3月的雨季。所有岛屿的本地植被覆盖也经历了NDVI的显着下降，背风，夏威夷岛的西南侧，我经历了最大的下降。夏威夷群岛1982-2019年的年总降水量和年平均帕尔默干旱严重度指数（PDSI）的长期趋势显示出明显的同步下降。原生生态系统NDVI与降水之间的主要正相关表明，降水的显着减少可能会加剧原生生态系统NDVI的减少。NDVI-PDSI相关性主要在岛屿的迎风一侧为负，在背风一侧为正，表明背风原生生态系统对干旱的敏感性更高。原生景观的年代际时间序列和空间明确数据为自然资源管理者提供了与植被健康和稳定性相关的长期趋势和每月变化。
