Modelling invasive plants in Central European cultural landscapes – does massive spread of giant hogweed (Heracleum mantegazzianum) threaten biodiversity

Basic data for this project

Description

Abstract: Giant Hogweed (Heracleum mantegazzianum) is an invasive alien species in Central Eurpean cultural landscapes that begann to spread rapidly in the 20th century affecting native plant communities. Whether implications of giant hogweed will be problematic for native species and communities, depends on the proportion of habitat occupied at the end of the invasion process. We followed the spread of giant hogweed in 20 landscape sections (1 km² each) over a period of seven years and built a spatially-explicit model (cellular automaton) that simulates the further spread in the next 100 years. In the following project phase, we will integrate a landscape model, which simulates changes of spatial configuration, amount and quality of invasible habitat, into the invasion model. The objectives of this project are (1) to forecast the future spread for different types of landscapes, (2) to elucidate relationships between invasion process and spatio-temporal landscape dynamics, and (3) to detect thresholds of landscape structure where massive spread becomes possible. Background: Previous studies have shown, that the invasion process of giant hogweed depends on landscape structure. For giant hogweed, the cultural landscapes of Central Europe are patch-corridor-matrix mosaics, with suitable habitat patches (e.g. waste ground, abandoned fields) interspersed into a matrix of unsuitable land-cover types (e.g. arable fields, agricultural grasslands, forest). Spread among habitat patches mainly occurs along corridors, such as roads and rivers. If habitat patches are close, spread can also happen without corridors. But larger strips of landscape matrix largely prevent spread because the seeds cannot be dispersed by wind over larger distances. The patch-corridor-matrix mosaic changes continuously through land-use change and anthropogenic disturbances. Particularly, the configuration of habitat patches in the landscape is variable, because a large part of suitable habitat disappears through succession and is recreated through disturbance or abandonment of land use. It is not known, if and how such landscape dynamics influence invasive spread. In order to understand plant invasions in changing cultural landscapes and to make realistic forecasts of impacts on native species and ecosystems, it is necessary to integrate spatially-explicit models of invasive spread and landscape change. The models will be parameterized with data on population biology and ecology of giant hogweed and will be validated using repeated field surveys of our study areas. This project is based on results and data sets of the EU project "Giant Alien" (www.giant-alien.dk).