The salt marshes
in the tourist resort of Jandia in the south of the island of Fuerteventura are
the only wetland of international importance on the Canary Islands. Strictly
protected from human use, they are nevertheless in danger - but from invasive
species. Such species originate from other parts of the world and are called
neophytes (in the case of plants) or neozoa (in the case of animals). Since
they can spread in the new habitat without their traditional enemies and
competitors, they sometimes have a considerable impact on local ecosystems.
For Playa de
Matorral, two species will be presented in more detail below.
A North American plant
(of the plant family Faboideae) was probably introduced from Mexico for
horticultural purposes on Gran Canaria and Fuerteventura. The species Desmanthus permanbucanus (Pigeon
bundleflower) is considered to be a proliferating weed. The Faboideae plants
are able to accumulate nitrogen as nitrate in the soil through nodule bacteria
in the roots. In agriculture, they are therefore planted as a green fertiliser.
In natural habitats, however, this causes a strong change in soil chemistry and
is a threat to plants adapted to nutrient-poor soils. This has an effect, for
example, in the barrancos, the erosion gullies in volcanic deposits on the
island. For more information, see Verloove, F. & Borges, L. M., 2018: On
the identity and status of Desmanthus (Leguminosae, Mimosoid clade) in
Macaronesia, Collectanea Botanica 37
(https/doi.org/10.3989/collectbot2018.v37.007).
Desmanthus permanbucanus produces a large quantity of small
seeds that accumulate in the soil as a seed reservoir and germinate when
conditions are favourable. With this dispersal strategy it is difficult to
control, as seeds are always left behind that can germinate later. The plant is
controlled by pulling out seedlings before they can form seeds themselves or by
using plastic sheeting in areas containing seeds.
Either opaque
plastic is used to keep the moisture in the soil under the sheeting. The plants
that germinate then perish due to the lack of light. With transparent plastic
film, germination is accelerated. This makes it easy to observe the growth and
the seedlings are then removed.
The ubiquitous North
African bristled squirrels (Atlantoxerus
getulus) are very popular among tourists. Although there are signs in many
places urging people not to feed the animals, many people do not comply.
Sometimes they even feed right next to prohibition signs. The Atlas squirrels
were brought to the island of Fuerteventura as pets in 1965 and were able to
spread almost everywhere due to the lack of natural enemies. Only in hotel complexes
with cats no squirrels are found.
They are
considered pests for the island's agriculture and a threat to native plants and
animals. They compete for food with the native Eastern Canary Island lizard (Gallotia atlantica) or cause changes in
the composition of plant communities. For example, they support the spread of
prickly pears, which are also not native to the Canary Islands. Their juicy
fruits are readily eaten by the squirrels on the very dry island. The aim is to
prevent the squirrels from spreading to other islands (e.g. through ferry
traffic). First settlement attempts on Gran Canaria or Lanzarote were probably
successfully stopped.
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