DOES HABITAT FRAGMENTATION FAVOR THE POPULATION GROWTH OF Ligustrum lucidum Ait. (Oleaceae)? AN INVASIVE, ALIEN SPECIES IN CENTRAL ARGENTINA

AGUIRRE ACOSTA, NATALIA; MARIA DEL CARMEN MANDUJANO; AGUILAR, RAMIRO

Salvador de Bahía

Congreso; XI Congreso Latinoamericano de Botánica, LXV Congreso Nacional de Botánica y XXXIV Encuentro regional de Botánica.; 2014

Asociación Latinoamericana de Botánica y Sociedad Botánica de Brasil

Anthropogenic disturbances such as habitat fragmentation promote the arrival and establishment of invasive alien plant species by offering emtpy niches in modified habitats that can easily be occupied by more competitive species. However, little research has been conducted on the population dynamics of invasive plant species after they have been established for several years in fragmented habitats. In this work we use projection matrix models to evaluate whether habitat fragmentation or continuos forest promotes the population growth of the invasive tree Ligustrum lucidum Ait. (Oleaceae) in central Argentina. We marked and followed individuals of the species in both landscape conditions and measured their growth throughout four years. We obtained the transition matrices and lambda values per year and per condition. We determine the processes that have most contributed to the current population growth using retrospective analyses (LTRE). The results indicate that population growth is similar in both landscape conditions (95% of CI), with λ = 1.0195 (±0.00271) in continuous forests and λ = 1.0282 (±0.02007) in fragmented forests. In addition, values of population growth are grater than one, indicating that populations are increasing. Retrospective analyses indicate that the processes that contribute most to the current lambdas are fertility for populations in continuous forest and individual growth for populations in fragmented forests. Results suggest that populations in contrasting landscape conditions achieve population increase from different strategies in each condition. Higher fertility in populations of continuous forest may be due to increased pollinator fauna and/or better soil abiotic conditions, while higher growth of individuals in populations from fragmented habitats may be due to higher light incidence in forest patches and lack of competiors. Our results suggest the needed of urgent measures to control Ligustrum lucidum as the species is capable to colonize disturbed or preserved forest habitats.