Beyond the paper: lessons learned from managing invasions in extreme ecosystems

Posted on January 28, 2026January 30, 2026 by David Zeleny

The post provided by Eduardo Fuentes-Lillo, Rafael Garcia, Jonas Lembrechts, and Anibal Pauchard

Invasion of *Pinus contorta* across the Patagonian steppe, southern Chile, showing a clear invasion gradient radiating from a propagule source. Dense pine stands in the background progressively transition into scattered individuals and isolated recruits within the native treeless steppe vegetation. This pattern illustrates the role of propagule pressure in driving invasion dynamics and highlights the vulnerability of historically treeless ecosystems to tree invasions. Photo credit: Laboratorio de Invasiones Biológicas (LIB)

This post refers to the article “Beyond Control: Short-Term Legacy Effects of Invasive Nonnative Trees May Halt Biodiversity Recovery” by Fuentes-Lillo et al., published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.70110)

Publishing a scientific article often feels like closing a cycle. However, for the Laboratory of Biological Invasions (LIB), this study is part of a long-term research effort focused on the invasion of Pinus contorta in Araucaria araucana forests and the Patagonian steppe was instead an opportunity to pause and reflect on what it truly means to conduct research and management in fragile, protected, and extreme ecosystems.

From the outset, we knew this would not be a straightforward study. Working in ecosystems where an endangered and protected species such as Araucaria araucana (Pewén, Monkey puzzle tree) plays a central role and entails a particularly high level of responsibility. Considering also that we work in a territory historically and culturally linked to indigenous communities belonging to the Mapuche people. Having a strong scientific question is not enough: every field decision must ensure that native vegetation is not disturbed, soils are not damaged, and the ecological processes that are still operating are not compromised. This translates into strict protocols, lengthy authorization processes, and often a bureaucratic burden that can be challenging, but is an unavoidable part of conducting responsible research in ecosystems of high conservation value.

This complexity is further compounded by the ecological context. The south-central Andes and Patagonia are systems characterized by harsh climates, difficult access, and very narrow sampling windows. In these fragile environments, the control of invasive alien species is not a single action, but rather a slow, costly process that depends heavily on fine-scale decisions. Each intervention requires careful planning and continuous coordination among researchers, managers, authorities, and local communities.

One of the most important lessons from this work is that managing an invasion does not simply mean removing individuals. In our case, removing Pinus contorta involved much more than cutting trees. Every action was designed to avoid damage to native vegetation, reduce soil compaction, and carefully manage the residues generated by removal. Pine litter and residual biomass, if not properly handled, can become a new barrier to native species regeneration by altering the microclimate, light availability, or even facilitating the establishment of other opportunistic non-native species. Even the decision of whether or not to cut down pine trees and how to manage the resulting biomass must take into account the perception and quality of the experience of tourists visiting these areas.

Working in extreme ecosystems makes this level of care even more critical. In Patagonia, for example, opportunities for native species to establish are scarce and brief. An additional disturbance—even a well-intentioned one—can delay regeneration for years or substantially alter ecosystem trajectories. For this reason, managing invasions in these contexts requires a type of intervention that differs fundamentally from large-scale or standardized actions: it demands precision, gradual implementation, and full awareness of the collateral effects that each decision may have on native vegetation, soils, and ecological processes. Intervening without this level of care can generate additional disturbances that further delay ecosystem recovery. This is without forgetting the presence of other threats (grazing, fires, and climate change) that can significantly alter the expected recovery trajectories after management.

This study also forced us to confront an uncomfortable but fundamental idea: some biological invasions alter ecosystems so profoundly that their effects do not disappear when the invader is removed. Pinus contorta has modified ecosystem structure, microclimate, and biological dynamics, generating ecological legacies that can persist for years. In ecosystems that have historically been treeless, such as the Patagonian steppe, these changes can push systems toward alternative ecological states, the reversal of which is not always guaranteed.

From our perspective, this paper reinforces a conviction built over more than 20 years of studying biological invasions in Chile, from the northern deserts to the cold Patagonian ecosystems, and from islands to high mountains: invasion management cannot be reduced to a single action or quick solutions. Experience across ecosystems has shown that addressing invasions requires long-term research, a deep understanding of ecological processes, and genuine integration between science and management. It is not only about intervening, but about intervening well—using appropriate protocols and making decisions informed by a realistic assessment of the limitations of management, particularly in protected, fragile, and extreme ecosystems.

This paper does not close a story. For the Laboratory of Biological Invasions, it is a reminder that managing biological invasions in extreme ecosystems requires patience, rigor, and decisions informed by a realistic assessment of their scope and limitations. Above all, when it comes to conserving what still remains, it is not enough to decide whether to intervene or not: the way management actions are designed and implemented—their timing, methods, and level of care—can be just as decisive for the final outcome as the decision to act itself.

Sequential control of *Pinus contorta* in contrasting ecosystems of southern Chile. Left: felling of invasive pines using chainsaws within *Araucaria araucana* forests in the south-central Andes, where control actions must minimize disturbance to protected native vegetation. Right: manual finishing using hand saws in the Patagonian steppe, applied after chainsaw cutting to complete removal and reduce collateral impacts on soils and surrounding native vegetation. The image illustrates how invasion management relies on carefully sequenced, context-specific techniques rather than standardized interventions. Photo credit: Laboratorio de Invasiones Biológicas (LIB)

Lessons learned

Removing the invasive species is not enough: The removal of the invader is only the first step. Without considering the ecological legacies it leaves behind—in soils, litter layers, seed banks, and biota—the recovery of native biodiversity may not occur, even years after control.
How we intervene matters as much as whether we intervene: In protected and extreme ecosystems, poorly designed interventions can cause more harm than benefit. Minimizing trampling, soil compaction, and damage to native vegetation is essential. The focus should be on what we want to keep, not just on what we want to eliminate.
Residue management is not a minor detail: Residual biomass and litter from invasive species can limit native regeneration or facilitate new invasions. Their management must be a central component of any control plan. This is a vital point for the management of invasive plants
Extreme ecosystems amplify mistakes: In Patagonia and the south-central Andes, regeneration windows are short. Small additional disturbances can delay recovery for years. It is also a call for patience; recovery (or restoration) processes are slow.
Advanced invasions leave deep and persistent legacies: When an invasion is highly consolidated, its effects can persist beyond invader removal and drive ecosystems toward states that are difficult to reverse without active restoration.
Early prevention remains the best strategy: This work confirms that acting late is costly, complex, and ecologically limited. Prevention or early intervention remains the most effective option.
Long-term research is irreplaceable: Without data collected before and after management, many of these processes would remain invisible. Long-term science is essential to understand what works, what does not, and why.

Brief summary: The Laboratory of Biological Invasions (Laboratorio de Invasiones Biológicas, LIB) is a research group based at the University of Concepción and the Institute of Ecology and Biodiversity (IEB), Chile, with more than 20 years of experience studying biological invasions across mountain, desert, forest, and Patagonian ecosystems. The lab integrates long-term ecological research with applied management to support evidence-based decision-making for biodiversity conservation and invasive species management.