Monitoring invasive tree species using satellite remote sensing in the temperate forests of south-central Chile

Abstract

Chile’s temperate forest is a global biodiversity hotspot due to its levels of endemism and rate of habitat loss. Deforestation and biological invasions are two major threats faced by this ecosystem. Both are produced by the expansion of productive forestry, which fragments the native forest and introduces alien species (from the Pinaceae family and Eucalyptus genus). Despite these threats, broad scale ground-based forest and alien species monitoring is not feasible due to logistical and budgetary limitations. Surveying and mapping alien species are key steps to understand biological invasions. This project uses remote sensing to understand biological invasions by alien trees from productive forestry in Chile’s temperate forest at different spatial scales. Sentinel-2 is used to assess alien tree occupancy and model its relationship with fragmentation and landscape configuration at a broad scale. A temporal assessment using Landsat historical archive imagery is used to investigate the dynamics of alien tree spread over the last 40 years. A local scale assessment using very high resolution WorldView-3 imagery and object-based image analysis is used to investigate early invasion and its relationship with land cover configuration. The results demonstrate remote sensing methods are useful for alien tree monitoring at different scales and hold potential for management. The expansion of alien trees at a broad scale is dominated by socioeconomic factors such as cost effectiveness and government subsidies. Alien Pinaceae tend to invade the naturally open Araucaria araucana forests, threatening the long term regeneration of this endemic and culturally relevant tree. Early Pinaceae invasion is linked to fragmentation, distance to seed sources, topography and human intervention. Incidentally, this study found that native forest degradation is occurring, increasing its vulnerability to invasion in the future. Conservation and forest management need to adopt sustainable, evidence-based practices to achieve compatibility between productive forestry and native forest conservation.

Date of Award	26 Oct 2021
Original language	English
Awarding Institution	Edge Hill University
Supervisor	PAUL APLIN (Director of Studies) & CLAIRE JONES (Supervisor)