Invasive plants species are being researched

José Pichel Andrés/DICYT The Palynology and Plant Conservation Group of the Spanish-Portuguese Institute for Agricultural Research (CIALE) of the University of Salamanca is studying invasive plant species in Castilla y León. In accordance with its preliminary studies, in the province of Salamanca alone there are some 80 species of foreign plants, many of which have become naturalised and are displacing native ones and therefore causing problems in various ecosystems.

“Some species are recent arrivals while others are virtually naturalised, and some cause more problems than others”, DiCYT was told by José Ángel Sánchez Agudo, one of the researchers. For the moment the team is engaged in documentary work and the drawing up of potential distribution models; field work will come later.

One of the best examples of allochthonous or exotic plants in the province of Salamanca is the species known as pampas grass (Cortaderia selloana), which comes from South America and is frequently seen in gardens. “Until recently it could only be found in Salamanca where it had been planted for ornamental purposes, but it is now being recorded spontaneously in many areas, especially on the fertile plain formed by the River Águeda, and there is no doubt that it is expanding”, the scientists point out.

Another case of note is that of the tree Acacia dealbata, known as the mimosa, which is frequently found in the wild in the southern sierras of Salamanca. The main problem of invasive plants is that they compete for the same habitat as autochthonous species and on occasion they may displace them because they have a greater capacity of proliferation.

In certain cases invasive species may cause problems to the ecosystem in general and even have a serious effect on animals. This is occurring with some aquatic species that may produce shade or generate a low concentration of oxygen, which has a detrimental effect on fish and other denizens of the waters they colonise.

The difficulty of taking action

Taking action in this situation is a very complex matter. “I think that this is a losing battle; the only thing we can do is encourage local species or control the expansion of these plants, as eradicating them is impossible”, José Ángel Sánchez Agudo points out, especially considering that when a problem is detected it has generally become very extensive.

The researchers are working with Geographic Information Systems (GIS) in order to draw up distribution models that can predict the presence of some species. These models include information from the places where a certain plant is to be found, for example the temperature, the precipitation, the topographical characteristics, or the human footprint in the form of infrastructures such as roads or towns. All this information is extrapolated to other areas to determine which places have the suitable characteristics for the presence of each species.

The mathematical models provide clues as to where to search, although there are other factors such as competition with other species that are very difficult to quantify. This is a vital part of the future field work that the group intends to carry out in the forthcoming years, as “thanks to them it will be possible to check the validity of these models and their possible improvement, and even to assess hitherto unknown aspects that have a considerable influence on the expansion of these species”.