The main threat to the threatened plant species in this group is intensified livestock farming, and especially overgrazing has the worst impacts. Plant species are directly affected through livestock eating them or due to trampling and increased nitrification. The conversion of grasslands into agricultural land for livestock, arable farming or forestry is a serious threat leading to habitat loss or at least degradation. On the other hand, many species are in need of moderate disturbance and were thriving well in areas under traditional agricultural use such as moderate grazing. Whereas an intensification of agricultural activities leads to the disappearance of those species on one hand, the complete abandonment of these activities poses also a serious threat. The abandonment leads to changes in the vegetation dynamic and succession of woody plants and shrubs that lead to an increased competition and therefore disappearance of plant species.
Recreational activities such as hiking, mountaineering or walking are the second biggest factor causing species to be directly or indirectly threatened. Ecosystems frequented by humans often notice a decrease in quality and the plants are in danger of being trampled. Invasive alien species and problematic native species are particularly threatening the flora on the Canary Islands and Madeira but also in the Mediterranean. Introduced plants such as Carpobrotus edulis and Opuntia ficus-indica aggressively compete for space, light and other resources with native species in a way that often leads to the disappearance of the latter. Grazing and trampling by introduced or native herbivores (such as rabbits, goats or sheep) impact several plants.
Many plant species are very attractive and therefore collected for their beauty. This collection ranges from the occasional picking to systematic collection for the horticultural trade, medicinal use or for food. It needs to be said that for many species under legislation the collection is already forbidden, restricted, or regulated although this does not exclude illegal activities.
A major driver of habitat loss is urban and tourism development as well as transport infrastructure which affects most of the policy plant species assessed. It is not only the fact that the plants cannot cope with a change of its habitat due to an increased use by humans. But the expansion of urban environments or the development of new tourist complexes or roads is creating impermeable, sealed surfaces and a loss of soil habitat for the species. Mining and quarrying is another driver of habitat loss and degradation.
Many species listed in this group are found in rocky areas, on cliffs, in scree or instable substrate and are vulnerable to geological events such as landslides and avalanches. Although this is not a human induced threat, it can seriously affect a population especially if the species is rare and found at very few localities or with a low number of individuals in the first place. Fires, which can occur naturally or be set by humans can have devastating effects on plant populations. The effects of climate change on the selected plant species namely establishes itself in the form of increased droughts, particularly in the Mediterranean area. Other impacts are an increase in storms and floods, habitat shifting and alteration, and temperature extremes.
Pollution comes in the form of water pollution and of garbage disposal. Water pollution is mainly caused by run-off from agricultural fields and the application of fertilisers, pesticides and herbicides which can be harmful to other plants or change the native species dynamic and increase competition. Especially plants bound to freshwater environments are affected by water pollution.
Last but not least, it should be noted that most plants are faced by more than one threat and that a combination of these can worsen the situation for a species even more, for example, increased drought also increases the risk of fires.