Controlling invasive pines in a grassland nature reserve: Proposal of optimization

CUEVAS, YANNINA A.; ZALBA, SERGIO M.; BOÓ, ROBERTO M.

Mérida, México

Congreso; Annual Meeting of The Ecological Society of America; 2006

Ecological Society of America

Ernesto Tornquist Provincial Park (Buenos Aires, Argentina), one of the most important biodiversity relicts in Pampean grasslands, is facing serious problems associated with the expansion of alien species. The extension and impact of the presence of Alepo pine  (Pinus halepensis) determined the need of facing the problem in an integrated and planned way, including long term objectives, and based on political, economic, technical, biological and social criteria. The present distribution of pine invasion was studied by means of aerial photographs. Different control techniques were evaluated  considering effectiveness, social and ecological impact and public opposition. Areas inside the reserve were prioritized according to their importance (conservation value), control feasibility (easy of access) and visual impact. The frequency for effective control was calculated considering key characteristics in the species reproductive biology. The costs and effort associated to these actions were estimated in experimental plots with different pine densities and from comparable management antecedents. Finally the main social groups interested in this problem were identified. Dense wildings (more than 600 trees/ha) cover 1% of the reserve, while the areas with intermediate (200 to 600 trees/ ha) and low density of pines (less than 200 trees/ha) reach 2 and 89% of the area respectively. Mechanical control and burning of felled trees and small seedlings are the methods that proved to be most appropriate, while herbicide treatment is a lower priority option. A control plan of pines is proposed with an  estimated total cost of 45830 U$S and 12586 working hours, with a six years effective control frequency. The basis of an education strategy is set for tourism operators, political authorities, local settlers and farmers.