Invasion of glossy privet (Ligustrum lucidum) and native forest loss in the Sierras Chicas of Córdoba, Argentina

Abstract

Glossy privet (Ligustrum lucidum) is a tree native to China that successfully invades forests of central Argentina. To fully understand glossy privet’s ecological effects on native forest, it is necessary to accurately map the distribution of glossy privet stands and the changes in biodiversity and forest structure of the invaded areas. The objectives of this paper were (1) to map the distribution of glossy privet stands in an area representative of the Sierras Chicas (Córdoba, Argentina) and (2) compare composition, structure and regeneration between glossy privet invaded stands and native forest stands. Using four Landsat TM images (October 2005, March, May and July 2006) we mapped the distribution of a glossy privet-dominated stand using a support vector machine, a non-parametric classifier. We recorded forest structure variables and tree diversity on 105 field plots. Glossy privet-dominated stands occupied 3,407 ha of the total forested land in the study area (27,758 ha), had an average of 33 glossy privet trees (dbh > 2.5 cm) per plot and the cover of their shrub and herb strata was substantially reduced compared with native forest. Forest regeneration was dominated by glossy privet in native forest stands adjacent to glossy privet-dominated stands. We conclude that in the Sierras Chicas glossy privet has become a widespread invader, changing the patterns of vertical structure, diversity, and regeneration in native forests.