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

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

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2020

1387-3547

Pine tree invasions threaten many naturalecosystems of the Southern Hemisphere, modifyingtheir structure and functioning through shifts in fireregimes, water balance, and biodiversity. The magnitudeof such impacts depends on how much of thelandscape has been invaded, thus a better understandingof the dispersal ability of pines and predictions oftheir future invasions are needed. Here we depict thespatio-temporal patterns of Pinus elliottii and Pinustaeda invading a new environment away from plantedplots (i.e., invasion front), and discuss the underlyingmechanisms that lead to a very concerning, yet poorlydocumented, pine invasion in central Argentina.Combining high-resolution imagery, allometric fielddata, and dendrochronology, we reconstructed the pineinvasion into mountain grasslands from its onset in1990. 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 decreases exponentially with distance from theplantation edge. Remarkably, invading pines werefound throughout the sampling plots showing highdispersal capacity, with no differences in age withincreasing distance. The observed low density andspatially widespread exotic pine establishment, createa stealth type of invasion that is difficult to perceive inits early stages and challenging to manage once largeareas are compromised. As invasion continues, longdistancedispersal will possibly become a major agentof landscape transformation and may lead to largepine-dominated neo-ecosystems, such as the savannalikeformation described here that replaced nativegrasslands in only three decades.