PYRTREELINEMOD

A model for Pyrenean Treeline: from individuals to landscapes under a changing climate

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 Obiettivo del progetto (Objective)

'Alpine ecosystems belong to the most endangered in the word, given their high sensibility to human induced impacts. Recent studies have detected a response of the boundary between subalpine forests and alpine zones (i.e. the treeline) to climate change, but there is an ongoing controversy about whether or not and how treelines may advance or retreat under current climate trends. This question is however of great interest for the biodiversity of alpine ecotones, and changes in the treeline would have important implications for the global carbon cycle. Thus, there is a need to understand the mechanisms shaping treelines and how different factors operate on them both at local and landscape scales. This project is designed to disentangle treeline dynamics, i.e. its spatiotemporal variation and long-term responses to climatic forcing and biological interactions using advanced modeling techniques and an extensive dataset of individual tree age, growth, position, size and recruitment in Pinus uncinata at the Pyrenean range. Spatially-explicit, individual-based models will be employed to simulate treeline spatiotemporal dynamics including both abiotic (temperature and precipitation, especially snow) and biotic factors (e.g. seed viability and dispersal, tree growth), as well as potential synergisms. First, modeling efforts will focus on the local scale and then, the entire Pyrenees will be modeled by upscaling, retaining only the relevant detail necessary to describe broad scale dynamics. Finally, the landscape scale model will be used to project treeline dynamics forced under different climate change scenarios generated through regional climate models. In all stages, a pattern-oriented modeling strategy will be used to examine the sensitivity of model predictions and assumptions, and to optimize model performance. The project will make a significant advance in finding reliable conservation policies for alpine areas, especially those related to climate change mitigation.'

Introduzione (Teaser)

Mountain ecosystems and the rare plants they contain are vulnerable to a changing climate. The result has been greater interest in tree lines, which are one of the best indicators of climate change. European researchers are investigating this further.

Descrizione progetto (Article)

Look up at a forested mountainside and you will see what appears to be a line, beyond which no trees can grow because of the cold and lack of moisture. But closer inspection shows that the transition is more gradual as trees become shorter towards the inhospitable conditions, until they cease growing altogether. This transition area between two different adjacent plant communities is known as an ecotone and may contain a number of unique local species.

Over recent decades tree lines have been reported as advancing, possibly as a result of increasing levels of carbon dioxide due to human activities. The ability of forests to thrive at higher altitudes can significantly increase the amount of carbon they contain, as well as reducing the available habitat for rare alpine plants. Therefore, changes to the tree lines around the world may have an important impact on the global carbon cycle and biodiversity.

Mechanisms underlying the formation of tree lines are not yet fully understood by scientists. This is a major limitation for predicting the future evolution of tree lines under projected climate scenarios for this century. The EU-funded Pyrtreelinemod project can help scientists better understand tree line dynamics and predict its future evolution in response to climate change.

Advanced computer modelling techniques and extensive datasets about individual trees will provide valuable information on the growth of the mountain pine (Pinus uncinata). This species is found at high altitudes across the Pyrenees. Models of tree line dynamics will include information about temperature and precipitation, especially snow, as well as seed viability and dispersal and tree growth.

Data from the Pyrtreelinemod project will provide scientists with a greater understanding of the impact of climate change on mountain environments and the global carbon cycle. This information can be used to take mitigating action to protect these fragile ecosystems and provide more accurate climate change models.