Land Cover Classification of Complex Agroecosystems in the Non-Protected Highlands of the Galapagos Islands

Abstract

The humid highlands of the Galapagos are the islands’ most biologically productive regions and a key habitat for endemic animal and plant species. These areas are crucial for the region’s food security and for the control of invasive plants, but little is known about the spatial distribution of its land cover. We generated a baseline high-resolution land cover map of the agricultural zones and their surrounding protected areas. We combined the high spatial resolution of PlanetScope images with the high spectral resolution of Sentinel-2 images in an object-based classification using a RandomForest algorithm. We used images collected with an unmanned aerial vehicle (UAV) to verify and validate our classified map. Despite the astounding diversity and heterogeneity of the highland landscape, our classification yielded useful results (overall Kappa: 0.7, R2: 0.69) and revealed that across all four inhabited islands, invasive plants cover the largest fraction (28.5%) of the agricultural area, followed by pastures (22.3%), native vegetation (18.6%), food crops (18.3%), and mixed forest and pioneer plants (11.6%). Our results are consistent with historical trajectories of colonization and abandonment of the highlands. The produced dataset is designed to suit the needs of practitioners of both conservation and agriculture and aims to foster collaboration between the two areas.

Oceanic islands and climate: using a multi-criteria model of drivers of change to select key conservation areas in Galapagos

“…Physical (e.g., rising air temperature, sea-level rise) and chemical changes (e.g., ocean acidification, O 2 concentration declines) can affect both the composition and biodiversity of insular communities and the various functions of the ecosystem, transforming their structure (Keener et al 2012;Ferreira et al 2016;Harter et al 2015). For example, rising sea surface temperature (SST) will result in increased rainfall that affects both low-and highland ecosystems, which likewise will alter plant growth and community structure, promote erosion, and provide better conditions for invasive species (Trueman and D'Ozouville 2010;Larrea Oña and Di Carlo 2011).…”

“…However, tourism has produced negative effects on the Galapagos natural environment, including the introduction of new invasive species, an increasing amount of waste, and growing use of local limited resources, mainly drinking water (Toral-Granda et al 2017;Epler 2007;Larrea Oña and Di Carlo 2011;Pizzitutti et al 2017). Besides the increasing number of tourists and invasive species, the Galapagos Islands face several other drivers of change, such as marine pollution, overfishing, and illegal fishing (Schiller et al 2014;Alava et al 2014;Salinas-De-León et al 2020).…”

“…However, islands higher than~200 m can permanently have a dense fog (Porter 1979). The spatial variation of rainfall with altitude creates a vegetation zonation pattern of three main regions in the Galapagos Islands: (1) the dry lowlands, also referred as the arid zone, which occupies the majority of the archipelago (83% of total land area); (2) the transition zones; and the (3) humid zone or the highlands (Larrea Oña and Di Carlo 2011).…”

“…The Galapagos Islands harbor over 600 plant species, of which 30% are endemic (Galapagos-Conservancy 2021) and mostly in the arid zone (Porter 1979). The humid zone has higher productivity due to its higher rainfall, which provides habitat for many native and endemic species (Larrea Oña and Di Carlo 2011). However, the humid zone is mostly degraded on inhabited islands due to land use and invasive plant species impacts (Laso et al 2020;Watson et al 2009).…”

“…The humid zone has higher productivity due to its higher rainfall, which provides habitat for many native and endemic species (Larrea Oña and Di Carlo 2011). However, the humid zone is mostly degraded on inhabited islands due to land use and invasive plant species impacts (Laso et al 2020;Watson et al 2009). Protected land areas are managed by the Galapagos National Park (GNP), which covers 97% of the land area in the archipelago (GNP, 2021)…”