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：岛屿生态环境具备独特的生物与非生物特征，因其脆弱性、自然资源有限性、地理隔绝性与生境破碎化等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的改造作用，借助时间序列与卫星影像研究手段，解析岛屿景观的自然演化过程具有重要研究价值。本研究旨在通过遥感影像，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（植被覆盖变化），结合城市发展与其他人类活动的影响，并与2005年及2017年编制的岛屿管理规划开展对比分析。同时，本研究旨在提炼相关研究结论，为该群岛的空间管理提供支撑，并为费尔南多·迪诺罗尼亚群岛及其他岛屿区域制定公共保护政策提供参考依据。本研究分别获取了1999年与2017年的Landsat 7与Landsat 8影像数据，在Quantum GIS 2.18软件中对影像进行预处理与分析，并开展了归一化植被指数（Normalized Difference Vegetation Index, NDVI）计算。同时，本研究采用了伯南布哥州政府提供的该群岛可持续管理规划数据库。基于上述数据，本研究诊断得出该群岛在17年间的植被覆盖率增长约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。但该群岛的植物群落多样性未发生明显变化，研究认为这一现象源于岛上已定植并持续扩散的入侵物种与杂草类物种。