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High spatial resolution mapping identifies habitat characteristics of the invasive vine Antigonon leptopus on St. Eustatius (Lesser Antilles)

Citation

Haber, Elizabeth et al. (2021), High spatial resolution mapping identifies habitat characteristics of the invasive vine Antigonon leptopus on St. Eustatius (Lesser Antilles), Dryad, Dataset, https://doi.org/10.5061/dryad.6wwpzgmxj

Abstract

On the Caribbean island of St. Eustatius, Coralita (Antigonon leptopus) is an aggressive invasive vine posing major biodiversity conservation concerns.  The generation of distribution maps can address these conservation concerns by helping to elucidate the drivers of invasion. We test the use of support vector machines to map the distribution of Coralita on St. Eustatius at high spatial resolution and use this map to identify potential landscape and geomorphological factors associated with Coralita presence. This latter step was performed by comparing the actual distribution of Coralita patches to a random distribution of patches. To train the support vector machine algorithm, we used three vegetation indices and seven texture metrics derived from a 2014 WorldView-2 image. The resulting map shows that Coralita covered 3.18% of the island in 2014, corresponding to an area of 64 ha. The mapped distribution was highly accurate, with 93.2% overall accuracy (Coralita class producer’s accuracy: 76.4%, user’s accuracy: 86.2%). Using this classification map, we found that Coralita is not randomly distributed across the landscape, occurring significantly closer to roads and drainage channels, in areas with higher accumulated moisture, and on flatter slopes. Coralita was found more often than expected in grasslands, disturbed forest and urban areas, but was relatively rare in natural forest. These results highlight the ability of high spatial resolution data from sensors such as WorldView-2 to produce accurate invasive species, providing valuable information for predicting current and future spread risks and for early detection and removal plans.

Methods

A field survey was conducted in July 2015 to collect ground-truthing data to allow for image classification, resulting in a distribution map of the invasive species Antigonon leptopus (referred to as 'Coralita'). On the Caribbean island of St. Eustatius. The resulting distribution of the species on the island comprised 1,852 patches; from each patch, a random location was selected, and additional landscape attributes were calculated for this locations. These characteristics, for all the 1,852 'Coralita' locations, were then compared to characteristics of 1,852 non-Coralita locations, selected randomly on the island of St. Eustatius. The .zip folder contains .txt files containing the land mass and Coralita distribution at 2 m resolution, and the landscape attributes for the 3,704 (i.e. 2*1,852) locations. 

Usage Notes

Please see the readme file in the .zip folder.

Funding

Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Award: 858.14.052