Forestry

Flora (microbiology)

Habitat

Ecology

Bacteria

Biology

Exclosure

Botany

Herbivore

Paleontology

Endemism

Genetics

Seedling

Mathematics

Geography

Elevation (ballistics)

Geometry

Endangered species

Biodiversity

Disturbance (geology)

Ecosystem

Species richness

Arctic Antarctic and Alpine Research

Novel disturbance regimes (e.g., introduced herbivores and fire) are among the major drivers of degradation in island ecosystems. High-elevation ecosystems (HEEs) on islands might be especially vulnerable to these disturbances due to high endemism. Here, data from an 11-year exclosure experiment in the HEE of La Palma (Canary Islands) are presented where mammalian herbivores have been introduced. We investigate the combined effect of herbivory and fire on total species richness, seedling richness, and seedling establishment on the whole system and a subset of highly endangered species (target species). Total species richness, seedling species richness, and seedling establishment decreased with herbivory. Five out of eight target species were exclusively found inside the exclosures indicating the negative impact of introduced herbivores on endemic high elevation flora. Target species were generally affected more negatively by introduced herbivores and were subject to significantly higher browsing pressure, probably owing to their lack of defense strategies. A natural wildfire that occurred six years before data sampling substantially increased total species richness and seedling richness in both herbivory exclosure and reference conditions. We conclude that species composition of the HEE has been severely altered by the introduction of non-native herbivores, even though fire seems to have a positive effect on this system.

Burned and Devoured-Introduced Herbivores, Fire, and the Endemic Flora of the High-Elevation Ecosystem on La Palma, Canary Islands