BioSCape Project

Impacts of Invasive Alien Species on Biodiversity and Ecosystem Functioning

Summary

This project will map invasive alien trees at a fine scale (5m) in three sites in the Cape Floristic Region of South Africa, using sensors mounted on NASA aircraft: AVIRIS-NG and LVIS. The field campaign ran from October to November 2023.

In addition, the aim is also to produce maps of structural and spectral diversity at both local (alpha) and landscape (beta) scales, and to spatially estimate an important ecosystem function using supplementary satellite data, specifically evapotranspiration (relating to water use impacts).

Using the map of invasive alien trees, as well as layers of diversity (spectral and structural), environmental covariates (e.g. elevation, aspect etc) and the ecosystem function evapotranspiration, three hypotheses will be tested:

Hypothesis 1: Higher structural and spectral alpha-diversity decrease invasibility, after accounting for confounding effects of landscape-scale covariates.

Hypothesis 2: As alien tree invasions progress, they increase structural and spectral alpha-diversity, but decrease beta-diversity.

Hypothesis 3: Ecosystem functioning (evapotranspiration) depends on both invasion status (H3A) and biodiversity (H3B).

Study Design

Study Sites

The mapping exercise will focus on three study sites within the Cape Floristic Region, targeting dense invasions of specific alien tree taxa, such as pine, wattle, gum and hakea.

One of the sites is in the Du Toits pass/Theewaterskloof Dam area, the third is on the Agulhas Plain, and the fourth is in the Swartberg.