Stealth invasions on the rise: rapid long-distance establishment of exotic pines in mountain grasslands of Argentina

TOMÁS MILANI; ESTEBAN G. JOBBÁGY; MARTÍN A. NUÑEZ; M. EUGENIA FERRERO; GERMÁN BALDI; FRANCOIS TESTE

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2020

1387-3547

Pine tree invasions threaten many natural ecosystems ofthe Southern Hemisphere, modifying their structure and functioning throughshifts in fire regimes, water balance, and biodiversity. The magnitudeof such impacts depends on how much of the landscape has been invaded, thus abetter understanding of the dispersal ability of pines and predictions of theirfuture invasions are needed. Here we depict the spatio-temporal patterns of Pinuselliottii and Pinus taeda invading a new environment away fromplanted plots (i.e., invasion front), and discuss the underlying mechanismsthat lead to a very concerning, yet poorly documented, pine invasion incentral Argentina. Combining high-resolution imagery, allometric field data,and dendrochronology, we reconstructed the pine invasion into mountaingrasslands from its onset in 1990. We found that even though the maximumdensity of invading pines (80 trees ha-1) was very lowcompared to adjacent plantation (1000 trees ha-1), density decreasesexponentially with distance from the plantation edge. Remarkably, invadingpines were found throughout the sampling plots showing high dispersal capacity,with no differences in age with increasing distance. The observed low densityand spatially widespread exotic pine establishment, create a stealthtype of invasion that is difficult to perceive in its early stages andchallenging to manage once large areas are compromised. As invasion continues,long-distance dispersal will possibly become a major agent of landscapetransformation and may lead to large pine-dominated neo-ecosystems, suchas the savanna-like formation described here that replaced nativegrasslands in only three decades.