Using aster multispectral imagery for mapping woody invasive species in pico da vara natural reserve (Azores Islands, Portugal)

Abstract

-This paper aims to assess the effectiveness of ASTER imagery to support the mapping of Pittosporum undulatum, an invasive woody species, in Pico da Vara Natural Reserve (S. Miguel Island, Archipelago of the Azores, Portugal). This assessment was done by applying K-Nearest Neighbor (KNN), Support Vector Machine (SVM) and Maximum Likelihood (MLC) pixel-based supervised classifications to 4 different geographic and remote sensing datasets constituted by the Visible, Near-Infrared (VNIR) and Short Wave Infrared (SWIR) of the ASTER sensor and by digital cartography associated to orography (altitude and "distance to water streams") of which the spatial distribution of Pittosporum undulatum directly depends. Overall, most performed classifications showed a strong agreement and high accuracy. At targeted species level, the two higher classification accuracies were obtained when applying MLC and KNN to the VNIR bands coupled with auxiliary geographic information use. Results improved significantly by including ecology and occurrence information of species (altitude and distance to water streams) in the classification scheme. These results show that the use of ASTER sensor VNIR spectral bands, when coupled to relevant ancillary GIS data, can constitute an effective and low cost approach for the evaluation and continuous assessment of Pittosporum undulatum woodland propagation and distribution within Protected Areas of the Azores Islands.Keywords:Remote Sensing; Invasive species; Pittosporum undulatum. USO DE IMAGENS MULTIESPECTRAIS ASTER PARA MAPEAR ESPÉCIES INVASORAS LENHOSAS NA RESERVA NATURAL DE PICO DA VARA (AÇORES, PORTUGAL) RESUMO -Este artigo teve como objetivo a avaliação das imagens multiespectrais ASTER para o mapeamento de Pittosporum undulatum, uma espécie lenhosa invasora, na Reserva Natural do Pico da Vara (Ilha de S. Miguel, Arquipélago dos Açores, Portugal). A avaliação foi efetuada através da aplicação dos métodos de classificação supervisionada per-pixel "K vizinhos mais próximos" (KNN), "máquinas de vetores de suporte" (SVM) e "máxima verosimilhança" (MLC) a quatro diferentes conjuntos de dados geográficos e de sensoriamento remoto constituídos pelas bandas multiespectrais do visível e infravermelho próximo (VNIR) e infravermelho de onda curta (SWIR) do sensor ASTER e, ainda, por cartografia digital associada à orografia (altitude e distância a linhas de água), da qual depende diretamente a distribuição espacial do Pittosporum undulatum. Em nível global, a maioria das classificações obtidas apresentou forte concordância e alta precisão. Em nível da espécie invasora estudada, as duas classificações mais precisas foram obtidas através da aplicação de MLC e KNN às bandas VNIR associadas ao uso da informação geográfica auxiliar. Em termos gerais, a qualidade dos resultados apresentados sofreu incremento significativo sempre que foi introduzida no esquema de classificação essa informação determinante para a ecologia e ocorrência da espécie (altitude e distância

Mapping invasive alien Acacia dealbata Link using ASTER multispectral imagery: a case study in central-eastern of Portugal

“…RS and Geographic Information Systems (GIS) are useful tools for mapping and monitoring invasive species and to predict areas of susceptibility for exotic species invasion (Joshi et al, 2004). RS provides multi-temporal records that can be integrated and used into a GIS in order to support monitoring and control activities of invaded sites Gil et al, 2014). Additionally, researchers have sought to exploit unique phenological, spectral, or structural characteristics of invasive species in digital multispectral imagery to distinguish them from the species around them (Underwood et al, 2003;Underwood & Ustin, 2007;Resasco et al, 2007).…”

“…Thematic Mapper and Enhanced Thematic Mapper Plus), SPOT (Satellite pour l' Observation de la Terre) and TERRA (particularly, ASTER -Advanced Spaceborne Thermal Emission and Reflection Radiometer) are well suited for mapping at the community level and have been used to map invasive species before (e.g. Cobbing, 2007;Lawes & Wallace, 2008;Viana & Aranha, 2010;Gil et al, 2014).…”

“…roads, distance to water lines, altitude, slope, soil type, lithology, etc.) are included in the classification process (Van der Wouw et al, 2011;Gil et al, 2014) to overcome the poor spectral separability (TD < 1.7) observed between some of the land cover categories.…”

Assessing the effectiveness of RapidEye multispectral imagery for vegetation mapping in Madeira Island (Portugal)

“…Due to climate constraints and the consequent general lack of free-of-charge satellite remote sensing data (e.g. Landsat) covering most oceanic islands, only few examples of vegetation mapping in these insular territories have been based on satellite remote sensing data [Gil et al, 2011[Gil et al, , 2013[Gil et al, , 2014Gil and Abadi, 2015] and none directly applied to Madeira Island. RapidEye is the first satellite system on its resolutions (spatial, temporal and radiometric) that provides a red-edge channel [Jung-Rothenhäusler et al, 2007].…”

The Priolo Atlas: A citizen science-based census initiative for supporting Pyrrhula murina habitat conservation and restoration policies in São Miguel Island (Azores, Portugal)

“…It became difficult to observe after 1920, and believed to be almost extinct until the 1960s (Bannerman and Bannerman, 1966;Van Vegten, 1968). The historical decline of this endemic species and its present small range (area of occupancy = 83 km 2 ; Ceia et al, 2011a) likely resulted from the widespread clearance of native forest for pastureland and forestry plantations of Cryptomeria japonica, and more recently, the spread of alien invasive plant species (especially Hedychium gardnerianum, Clethra arborea and Pittosporum undulatum; Ramos, 1995Ramos, , 1996aAubrecht, 2000;Ceia et al, 2011a,b;Gil et al, 2011aGil et al, , 2013Gil et al, , 2014 which replace the natural vegetation, suppressing the native biodiversity ) and reducing the regeneration of the natural vegetation (Ceia et al, 2011b;Heleno et al, 2010). The native laurel forest is now restricted to steep slopes, mostly above 400 m of altitude, limiting the Azores Bullfinch distribution which is entirely dependent on native forest for food during most months of the year (Ramos, 1995;Ceia et al, 2011b).…”