Invasive plants in the Ponziane islands. Let's take a closer look!

Flowering of Carpobrotus, invasive plant species native to South Africa. Island of Santo Stefano (picture by R. Frondoni)

1 April 2021

Upcoming series on invasive plant in the Ponziane Islands

But first, let's do a little refresh. What are alien plant species?

They are plants that have been introduced by man outside their natural area of distribution. The intentional introduction of plants has many reasons (foraging species, honey plants, collections, substrate stabilisers) but nowadays trade of ornamental species is the main cause. Plants that are introduced into geographical regions outside their origin areas are known as allochthonous (or alien or exotic).

And what are invasive plant species?

Due to the absence of natural control mechanisms (such as the predators and parasites of their origin areas), a few allochthonous species with high reproductive potential and efficient dispersal can spread rapidly and massively, with negative impacts on the environment, economy, and/or human health. In this case, they become invasive.

For some species, vegetative (or asexual) reproduction can take place and favour spreading. In this case, part of the parent plant (rhizome, stolons) is used to generate new individuals. This method does not require the investment needed to produce flowers and seeds, or the optimal environmental conditions and specific factors that often may lack in the new areas.

Why do we worry about invasive plants?

Only a small number of introduced species become invasive. However, biological invasions are getting more dangerous in conjunction with climate change and land use change, and invasive species are widely known as a major threat to biodiversity.

In natural habitats, invasive plants may deeply alter the invaded communities in different ways: they may shadow other plant species with damage to their photosynthetic activity; or develop dense and wide root systems that use all soil resources and space at the expense of existing plant species; or even modify the chemical and physical characteristics of soil, and therefore threaten indirectly the survival of other species.

When introduced species establish in natural areas that host species of conservation value, their spread is particularly alarming because it may cause the extinction of the most vulnerable plant or animal species. Invasive species are known as a major threat especially in islands, where they represent the main cause of extinction of rare and/or endemic (with narrow geographical distribution) species.

This process is particularly severe on the small islands of the Mediterranean Basin, one of the world’s richest regions in terms of number of species and plants important for their rarity or even uniqueness. In recent years, the number of invasive plants on the small Italian islands increased notably, as well as their levels of establishment and the extent of their distribution.

Focusing on prevention, management, and control of invasive species in the Ponziane archipelago means preserving the beauty and species richness of their natural landscapes!

So, stay tuned for more information about invasive plants in the Ponziane islands