Analysis of vegetation dynamics using the normalized difference vegetation index (NDVI) at the archipelago of Fernando de Noronha, Pernambuco, Brazil

Abstract: Island environments have specific biotic and abiotic characteristics, as fragility, limitation of natural resources, geographic isolation, and fragmentation are determining factors that directly affect these areas. Thus, it is relevant to understand the natural evolution of the landscape in the islands, considering the anthropic actions and climate changes in the transformation of vegetation cover, as a means of time series and study of satellite images. This paper aims to analyze the dynamics of the landscape (changes in vegetation cover) of the Fernando de Noronha Archipelago concerning urban development, and other anthropic activities that occurred between 1999 and 2018, through remote sensing images, to establish comparisons with the Island Management Plans that were elaborated in the years of 2005 and 2017. Also, this study intends to raise elements to assist in the spatial management of the Archipelago and to establish Public Conservation Policies for Fernando de Noronha and other island areas. Images from Landsat 7 and Landsat 8 were obtained for scenes from 1999 and 2017, respectively. These images were preprocessed and analyzed in Quantum GIS 2.18 software. And applied the NDVI calculation. It was also used the database found in the sustainable management plan of the archipelago provided by the state government of Pernambuco. With these data, it was possible to diagnose a vegetative growth on the island of about 45.36% in 17 years corroborating with the changes found in the data coming from the island’s management plan. However, there are no changes in the phytosociological diversity of the island, this cause is pointed out to the invading and ruderals species of the island that are established and propagate.

摘要：岛屿环境具备独特的生物与非生物特性，其脆弱性、自然资源有限性、地理隔离性与生境破碎化均为直接影响该类区域的决定性因素。因此，结合人类活动与气候变化对植被覆盖转化的影响，借助时间序列分析与卫星影像研究手段，解析岛屿景观的自然演化进程具有重要意义。本研究旨在借助遥感影像，分析1999年至2018年间费尔南多·迪诺罗尼亚群岛（Fernando de Noronha Archipelago）的景观动态（即植被覆盖变化）及其与城市开发及其他人类活动的关联，并与2005年、2017年编制的《岛屿管理规划》开展对比分析。此外，本研究旨在梳理相关支撑要素，为该群岛的空间管理工作提供辅助，并为费尔南多·迪诺罗尼亚群岛及其他岛屿区域的公共保护政策制定提供参考。本研究分别获取了1999年与2017年的陆地卫星7号（Landsat 7）、陆地卫星8号（Landsat 8）影像数据，在量子地理信息系统2.18（Quantum GIS 2.18）软件中对影像进行预处理与分析，并开展了归一化差分植被指数（NDVI）计算。此外，本研究还采用了巴西伯南布哥州政府提供的该群岛可持续管理规划中的数据库。基于上述数据，本研究测算得出该群岛在17年间的植被覆盖率增长约为45.36%，这一结果与群岛管理规划数据中呈现的变化趋势相符。但该群岛的植物社会学多样性并未发生明显变化，这一现象的成因被归结为岛上已定植并扩散的入侵物种与杂草类物种。