When the term invasive species is mentioned, many of us probably think of the infamous giant hogweed (Heracleum mantegazzianum) or ailanthus (Ailanthus altissima), which are spreading through the Czech landscape. These and other invasive species represent one of the world's greatest environmental problems nowadays. Their success is due to their extraordinary ability to spread, but also to the absence of natural enemies in newly conquered habitats.
The spread of invasive species may seem random and unpredictable at first glance, but the opposite is true. Development of the dispersion can be relatively reliably predicted using predictive models that evaluate the dependence of the occurrence of a given invasive species on the expected development of environmental conditions. Most such models are based almost exclusively on the development of climatic factors, which until recently were considered to be the main driving force behind the spread of invasive species. In today's world, the ubiquitous human activity in the landscape is no less important, but it is often neglected in predictive models. The influence of human activity can be described as the so-called land cover and land use change. An example of a land cover could be a forest and land use change its felling and conversion to agricultural land.
One such predictive model was created by a group of authors, including a scientist from the Faculty of Forestry and Wood Sciences of CULS, for the Rhododendron ponticum, which is a problematic invasive species in Wales. This evergreen shrub was brought to the British Isles from southern Europe in the 18th century for ornamental purposes. After that, however, the shrub settled forest stands, keeps displacing the native species and prevents their natural regeneration. The model is exceptional mainly because it includes both climate development and changes in land cover and its use until 2030. Various scenarios were taken into account, both optimistic and pessimistic, assuming significant changes in the landscape and deforestation, but also a variant of stricter nature protection. It turned out that in the case of the rhododendron, it is the changes in land use that have the greatest impact on its spread, followed by altitude and average daily temperature.
What kind of future does the model prophesy to the rhododendron in Wales? It doesn't look very promising. Currently, 52% of the country's territory is suitable for its potential settlement. However, all scenarios suggest that this percentage should decrease in the future. The decline of suitable habitats will be recorded especially in south Wales, due to the decrease of ??coniferous forests in the area, which the shrub prefers. In recent years, there has been an effort in Wales to convert coniferous forests into native deciduous ones. On the other hand, the north of the country could provide new shelters due to the advancing warming. However, the ways of the Lord (and the climate change) are unpredictable, therefore only time will show what fate awaits this purple-flowering shrub…
Prof. Ing. Martin Lukáč, Ph.D. M.I. Soil Sci.
Professor Lukáč is a member of the Department of Forest Management at the Faculty of Forestry and Wood Sciences. He also works at the University of Reading in the United Kingdom. His research focuses on how to increase the diversity of agricultural and forestry management systems with a goal of achieving the long-term sustainability. The areas of interest include mainly the agroforestry, silviculture of mixed forests and the promotion of biodiversity in the landscape.
Author: Dagmar Zádrapová