Invasion of Ligustrum lucidum (Oleaceae) in subtropical secondary forests of NW Argentina: declining growth rates of abundant native tree species

MALIZIA, AGUSTINA; OSINAGA-ACOSTA, ORIANA; POWELL, PRISCILA ANA; ARAGÓN, ROXANA

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2017

1100-9233

Aims. Ligustrum lucidum, native of China, is one of the dominant exotic and invasive tree species in secondary forests of Argentina. 1) We assessed its invasion during 20 years in post-agricultural secondary forests dominated by native tree species, and 2) Evaluated tree demography rates of native individuals under and away of L.lucidum trees that invaded these forests.Locations. Four 1-ha permanent plots of secondary forests in subtropical Andes of Tucumán, Argentina.Methods. We quantified the invasion of L.lucidum individuals (≥ 10 cm diameter) from 1991 to 2011 within four 1-ha plots of secondary forests; and analysed annual growth and mortality rates of native tree individuals (also ≥ 10 cm diameter) under and away of L.lucidum trees that invaded these forests. For this, we compared tree demography rates of all native individuals together (community level) under individuals of L.lucidum and away, i.e. under individuals of native species (refer as exotic and native neighbourhoods, respectively); then we described the relative growth rate of native species in exotic / native neighbourhoods (species level) and related them with their demographic life histories and morpho- physiological traits.Results. L.lucidum increased from 0.1 to 4% in both density and basal area between 1991 and 2011. Importantly, native tree individuals grew 65% less in exotic neighborhoods compared to native ones. Relative growth rate showed negative values for the abundant species Ocotea porphyria, Parapitadenia excelsa, Juglans austalis and Allophylus edulis indicating competition under L.lucidum individuals; while less abundant species such as Terminalia triflora, Cupania vernalis and Blepharocalix saliscifolius showed positive values implying a facilitation processes. Thus, L.lucidum compete with some native tree species efficiently, particularly with those abundant species that showed characteristics such as faster diameter growth rates, exposed crowns, and which tended to be light demanding. Conclusions. Ligustrum lucidum is invading post-agricultural secondary forests dominated by native tree species. While invading, L.lucidum competes with native tree species that are abundant and compose the main structure of the forest canopy. As this invasive trend is likely to increase in the near future, L.lucidum may alter forest structure, composition and dynamics as well ecosystem functioning.