Pine tree invasions threaten many natural ecosystems of the Southern Hemisphere, modifying their structure and functioning through shifts in fire regimes, water balance, and biodiversity. The magnitude of such impacts depends on how much of the landscape has been invaded, thus a better understanding of the dispersal ability of pines and predictions of their future invasions are needed. Here we depict the spatio-temporal patterns of Pinus elliottii and Pinus taeda invading a new environment away from planted plots (i.e., invasion front), and discuss the underlying mechanisms that lead to a very concerning, yet poorly documented, pine invasion in central Argentina. Combining high-resolution imagery, allometric field data, and dendrochronology, we reconstructed the pine invasion into mountain grasslands from its onset in 1990. We found that even though the maximum density of invading pines (80 trees ha⁻¹) was very low compared to adjacent plantation (1000 trees ha⁻¹), density decreases exponentially with distance from the plantation edge. Remarkably, invading pines were found throughout the sampling plots showing high dispersal capacity, with no differences in age with increasing distance. The observed low density and spatially widespread exotic pine establishment, create a stealth type of invasion that is difficult to perceive in its early stages and challenging to manage once large areas are compromised. As invasion continues, long-distance dispersal will possibly become a major agent of landscape transformation and may lead to large pine-dominated neo-ecosystems, such as the savanna-like formation described here that replaced native grasslands in only three decades.

松树的入侵威胁着南半球的许多自然生态系统，通过改变火势，水平衡和生物多样性来改变其结构并发挥作用。这种影响的严重程度取决于已入侵的景观数量，因此需要更好地了解松树的扩散能力并预测其未来的入侵。在这里，我们描绘了松树和taeda的时空格局入侵远离种植地的新环境（即入侵前沿），并讨论导致阿根廷中部非常令人关注但文献记载不足的松树入侵的潜在机制。结合高分辨率图像，异地野外数据和树木年代学，我们从1990年开始就将松树入侵重建为高山草原。我们发现，即使与之相比，入侵松树的最大密度（80棵树ha ^-1）也非常低。邻近的人工林（1000公顷^-1），密度随距种植边缘的距离呈指数下降。值得注意的是，在整个采样区都发现了入侵的松树，显示出较高的分散能力，并且随着距离的增加，年龄没有差异。观察到的低密度和空间分布广泛的奇异松树形成了一种隐身型入侵，这种入侵很难在早期阶段感知到，一旦大面积遭到破坏，就很难进行管理。随着入侵的继续，长距离扩散可能会成为景观转变的主要推动力，并可能导致以松树为主的新生态系统，例如此处描述的稀树草原形式，仅在三十年内就取代了原始草原。