First symposium on alien plant invasions in Chile


The first symposium on Alien Plant Invasions in Chile was held in Puyehue, Southern Chile in November 14th as part of the 45th Annual Meeting of the Biological Society. The symposium discussed alien plant invasions and their status in Chile. The initiative was the first in bringing together specialists to discuss the global phenomena of alien plant species from a Chilean perspective.

Chile presents an interesting setting to study biological invasions. Chile has a long history of introduction with ca. 723 alien plant species (Concepción Herbarium unpublished data). The country also has a high rate of endemisms, due to its biogeographic isolation, which make it susceptible to invasion processes. Furthermore, Chile is one of the few countries with temperate ecosystems in the Southern Hemisphere, allowing for interesting comparisons with Australia, New Zealand and South Africa as well with climatic parallels in the Northern Hemisphere.

On the other hand, even though invasions are recognized as a major threat to biodiversity worldwide, little is known in developing countries about these processes. Currently, Chile lacks a clear policy on alien species. Research has been done sporadically, without a unified conceptual framework and with little coordination among institutions. This symposium offered a first opportunity to review the existing evidence about plant invasions in Chile and to discuss future challenges for research and management.

Ramiro Bustamante, the chair of the symposium illustrated the importance of studying invasions in Chile, highlighting some of the major challenges in studying alien plant invasions in Chilean ecosystems.

Eduardo Rapoport discussed the characteristics of human developments as sources of propagules for plant invasions. He presented data from London, Mexico City and Bariloche, showing that alien species tend to concentrate around urban developments and decreased in their abundance in natural areas. He also emphasized in the use of multiple scale methods to study invasions. Finally, he suggested that many exotic plant species are edible and may be an additional source of food for urban people.

Aníbal Pauchard emphasized the importance of the landscape context and corridors in the introduction of alien species in protected areas. He presented data from two Chilean national parks, where alien species in roadsides are related to elevation, land use and landscape context. He concluded that alien species should be controlled before entering natural areas by managing the matrix that surrounds protected areas.

Pablo Becerra, using data from several published studies, searched for relationships between native communities and invasibility in forests from Central and Southern Chile. He studied the effects of vegetation cover, native species richness, tree canopy cover and the pool of alien species on alien species richness. He concluded that overall vegetation and canopy cover is negatively correlated with alien species richness. However, he found no clear trend in alien vs. native species richness.

Ramiro Bustamante presented results on the invasion of Pinus radiata (Monterrey pine) into Nothofagus forest fragments of Central Chile, currently surrounded by industrial pine plantations. He found that most P. radiata seedlings tend to grow in fragment edges, reaching the interior only in highly disturbed forest fragments. He suggested that these forests are still resistant to the invasion of Pinus radiata, but monitoring is needed to assess invasion processes in the long term.

Lohengrin Cavieres concluded the symposium with general recommendations, elaborated previously by all guest speakers, about the future and challenges of plant invasion ecology in Chile. The package of recommendations may be useful for other developing countries with similar state of knowledge of their flora and similar environmental and economic issues.

The recommendations included:

1) Develop an inventory of alien species, identifying those species that are or may become invasive. In developing countries, the distribution of the flora is still poorly understood. Alien species have been neglected in collections and studies due to a historical bias that found no scientific value in studying alien component of plant communities. Thereby, major efforts are needed to complete herbarium records of alien species across the country.
2) Study patterns and processes of alien invasions in native communities of Chile. The few studies that have been conducted in alien plant species in Chile are mainly focused on describing patterns of distribution and abundance. However, few have tried to understand the mechanisms behind invasions, both in consideration of the invaded community and the invader.
3) Study the autoecology of those alien species recognized as aggressive invaders. Globally, the study of the characteristics of alien species that allow them to overcome ecological barriers and become invaders have been strongly emphasized. In Chile as in other developing countries, few studies have addressed invasions from the perspective of the invader. These studies while only provide a partial vision of the complex invasion process, are needed to understand and manage the most aggressive invaders.
4) Study the economics and biological impacts of alien species. Alien species not only affect ecological values, but also have a strong impact on economic activities. Currently, there is no assessment of impacts of invasions in either of these elements, limiting the efficiency to manage them and our capacity to prioritise limited resources.

Chile, as many other developing countries, faces similar challenges in the study of alien plant invasions, but it also offers a unique opportunity to study biological invasions in the Southern Hemisphere. We expect that this symposium had helped to stimulate the scientific debate about invasion ecology, promoting the development of coordinated research on the topic that could help to answer local questions, while contributing to find generalities in patterns and processes associated with plant invasions.

by Aníbal Pauchard, Lohen Cavieres, Ramiro Bustamante, Pablo Becerra and Eduardo Rapoport