Quantifying the impact of the invasive N2-fixing Acacia longifolia across spatial scales
P 2.7 in Research in its Prime: First Results of Ongoing Research
Invasive species are known to seriously alter structure and functioning of the ecosystems they invade. However, few studies consider the spatial dimension of these influences.
We investigated the impact of the exotic N2-fixing A. longifolia on N dynamics in a nutrient-poor dune system at the Atlantic coast of Portugal. As A. longifolia introduces symbiotically fixed N with a distinct isotopic signature, changes in δ15N of the endemic shrub Corema album could be used to trace and spatially resolve the influence of the invader on N dynamics of native species. C. album foliar δ15N values increased significantly from ‑11‰ to values close to 0‰ as a function of distance to the invader, indicating that A. longifolia enriched the system with atmospherically derived N (~0‰). The influence reached up to 8 m into the uninvaded vegetation, thus revealing marked alterations far beyond the physical extent of A. longifolia stands, and highlighting the need to consider spatial scales when looking into impacts of invasive species.
In our current project we will use hyperspectral remote sensing, which is a highly suitable tool to address spatial questions in ecological studies by allowing to quantify alterations in native species biochemistry on the leaf level using spectral measurements while permitting to scale up to the landscape level using aerial images. We aim to quantify changes in ecosystem functioning after plant invasion from leaf to landscape scale using hyperspectral remote sensing.