Managing the early warning systems of invasive species of plants, birds, and mammals in natural and planted pine forests

Plantations with alien forest species could be a major way for invasive plant and animal species to become introduced and naturally established in a territory, but the sensitivity of plantations with native forest species to invasive plant and animal species is still unknown. This paper studies the probability of the presence and the richness of invasive species of three different taxa (plants, birds, and mammals) in pine forests of southwestern Europe. To do so, the relative contribution from natural and planted forests is analysed to explain the presence and the richness of invasive species in 3,950 cells (10 km x 10 km) covering Spain after controlling for the possible effects of variables related to geography, climate, land use, landscape, and human pressure on the environment. Our results show that man's influence on the establishment of invasive species is notable. However, those forests that are the most intensely managed by man, such as pine plantations with native species, seem less susceptible to the establishment and propagation of invasive species. Reasons may be found in those planted pine forests being closely monitored, controlled, and managed by man. Therefore, it is argued that efforts related to the early warning systems of invasive species should be focused on natural pine forests.