Context and objectives
Plant species invasions are among the most important threats to the functioning of the earth’s ecosystems. Invasion biologists have mainly focused on the effects of invasive plant species on native populations and communities. The response of ecosystem functioning to invasion has received considerably less attention. Although invasive species impact proposedly can be predicted using a comparative analysis of their functional traits and these of the native community, this approach has rarely been used. Here, we will explore the capability of remote sensing instruments to define optically distinguishable functional types (‘optical types’) in order to quantify the effects of invasive plants on ecosystem functioning. State-of-the-art hyperspectral sensors allow to characterize the vegetation chemistry and canopy water content, to discriminate between subtle physiological differences among plant species, at the same time providing a link to ecosystem effects of the species. We predict that the optical types will outperform, or at least complement, the conventional functional trait approach when predicting changes in ecosystem functioning through plant invasion, both regarding accuracy and potential for generalization up to larger spatial scales.
The general objective of this project is to develop a novel ‘optical types’-based approach to evaluate and to predict the impact of invasive plant species on ecosystem functioning. The principal idea behind the proposed approach is that invasive plant species often have physical-chemical properties that differ from native species. These physical-chemical properties can be directly linked to ecosystem functioning changes following invasions, and they can be largely quantified based on the optical reflectance spectra of the species, which are detectable due to recent developments in hyperspectral remote sensing technology.
This proof of concept study will focus on herbaceous species that grow in open habitats.
Expected scientific results
This project, if successful, will result in a better understanding of the impact of invasive plant species and deliver a useful tool for performing environmental risk assessment analyses in invaded ecosystems. The concept of optical types offers an innovative and potentially transformative approach for linking optical properties (accessible with remote sensing) with ecosystem function. The approach is expected to be complementary with traditional functional trait-based approaches, on top offering the benefit for upscaling to the landscape level. The optical type approach is also very promising in the broader global change field, as it may allow to predict ecosystem functioning response to other global change processes such as climate change or large scale eutrophication.
Expected products and services
Our approach has potential as a Risk Assessment tool. Once a potential invader is identified, its spectral properties can be measured using a field spectroradiometer (i.e. proximal sensing). The invader’s optical type can then rapidly be determined by comparing the spectral properties of the invader to a yet to be established publicly available online library of optical types and their potential impacts on ecosystem functions. So, once we have identified the optical type we immediately know the harmful potential of the invader.
Furthermore, the project results will contribute to the set up of a remote sensing supported pipeline for an operational warning system.
- Policy makers at national, regional and local level (=> legislation regarding dangerous invaders);
- Scientific research community on invasive plant species (=> use and expansion of the online library with optical types linked to ecosystem impacts);
- Professional land managers and nature conservationists (=> targeted eradication of dangerous invaders).
|Project leader(s):||KULeuven - Department of Earth and Environmental Sciences (EES)|