In recent decades, the peatlands have experienced higher temperatures and prolonged droughts, which may have accelerated the invasion of mountain pines (Pinus uncinata), a species characteristic of European mountains. This invasion severely impacts the health of these delicate ecosystems.

During June and July, significant technical restoration actions were carried out in the mires of Locampo and Parros as part of the project to address this threat.

Interventions in Locampo: A wetland partially forested by Pinus uncinata

The Locampo mire in the Ruda Valley (Val d’Aran) have seen a significant increase in the presence of mountain pines in recent decades. Although these trees have been present in the valley for a long time, their growth has been particularly rapid over the last 30-50 years, altering the balance of the mire.

In response, this past spring, selective clearcutting of pines was carried out on nearly 2 hectares of mires in the Peripheral Zone of the Aigüestortes and Estany de Sant Maurici National Park. The objective was to reduce the density of the pines and restore the ecosystem’s balance. More specifically, all pines from a recently colonized and densely populated area were cut and removed, restoring the open peatland and preserving the herbaceous plants and moss populations.

In the adjacent mire, the approach was to reduce the density of the pine population, preserving only the larger or older trees and removing the young, fast-growing ones or those rooted directly in the wettest parts of the system.

Interventions in Parros: A wetland dominated by springs, seeps, and runoff water

In the lower part of the Parros Valley, near Montgarri, the situation is similar. The mountain pine population has densified, and junipers (Juniperus communis) have invaded the mire, reducing the space available for plants and mosses typical of subalpine wetlands.

Clearcutting in this area also covered nearly 2 hectares of wetland systems. Most of the pines—especially the young or small to medium-sized ones—were removed, and the area occupied by junipers was reduced, thereby improving the conservation status of the alkaline fens.

Collaboration for Conservation

These activities have been carried out in collaboration and coordination with the Aigüestortes and Estany de Sant Maurici National Park and the Conselh Generau d’Aran. This joint effort ensures the success of the interventions and proper monitoring of the conservation status over the coming years, making these actions effective not only in the short term but also in the medium and long term.

The LIFE RESQUE ALPYR project continues to work to protect and restore the subalpine wetlands, ensuring that these ecosystems continue to play their vital role in the environment.

In Alpine-type mountains, because the physiography is very complex and abrupt, these semi-aquatic ecosystems occupy very small areas, linked to the relief units where the phreatic water remains next to the soil surface, such as margins of ponds or edges of streams or fountains.

These wetlands are ecosystems with particular conditions, since the soil waterlogged. This soil conditions of hypoxia or anoxia imply important limitations for plants and other soil organisms. The poor oxygenation of the soil causes the plant litter (roots and fallen aerial parts) and other organic remains decompose very slowly, and, therefore, the organic matter accumulates in the form of peat.

Another common fact in these mires is the low concentration of mineral nutrients that their waters hold, which makes them a moderately to extremely oligotrophic and acidic environment, a situation that translates into moderate to low plant growth rates.

Fragile and vulnerable environments

They also offer refuge to highly specialized species, a lot of which being unique and rare species. Among them are some species of Carex or Sphagnum only found in a few Pyrenean localities.

Due to these particularities, both the vegetation and the organisms that live in peatlands are very sensitive to environmental changes. Among these changes, stand out the decrease in precipitation, the increase in temperatures and human activity.

The loss and degradation of peatlands that has occurred in recent decades has led to a decrease of 70% of their total area in Europe.

The abandonment of traditional uses of the mountains, one of the causes of the colonization of trees in these mires

The majority of peat bogs in the Pyrenees do not host adult pines, but the colonization and growth of trees in these mires has more than doubled in the last 70 years, details researcher Eulàlia Pladevall from the University of Barcelona. This sharp increase is due to the abandonment of traditional land uses, the global increase in temperature, and the prolongation of summer drought periods.

“The presence of pine trees in the peat bogs also dates back to ancient times. But in many cases, especially in those at moderate elevations, the tree cover has increased significantly, going from very sparse stands of poorly grown pine trees to moderately dense covers,” adds professor Josep M. Ninot.

The expansion and growth of trees in areas with peat bogs causes a decrease in available water, compromising the long-term conservation of these habitats. The shade generated by the tree crowns also harms the biodiversity of the peat bogs, since the intensity of light that reaches the herbaceous plants and mosses is lower.

Recovery tasks for high mountain peatlands

This summer season, the selective felling of trees carried out in Pla Muntaner, within the heritage mountain of “Tossal, St. Magi, Castell and Abad” of the Generalitat of Catalonia in the municipality of Montferrer and Castellbò, which is located in the Alt Pirineu Natural Park.

“The action has been able to be carried out completely this beginning of summer, preventing that it did not affect any habitat or sensitive species. The combination of volunteers and professional forestry workers in this task has at the same time allowed for effective work and an improvement in the environmental awareness of citizens through volunteering in nature restoration actions such as this one,” declares Marc Garriga, director of the Alt Pirineu Natural Park.

The task of felling, clearing branches and stacking remains has been carried out through volunteers (with hand tools) and workers (with chainsaws) from the Mountain Forests Project Foundation, with the participation of eight volunteers, and it has allowed 2,050 trees to be cut in 2.4 hectares that encompass the 1.5 hectare peat bog. Five tree groups (about five trees each) have been left for the purpose of wildlife refuge. As far as possible, work has been done with manual means to avoid damaging the peaty system.

The extraction of the logs generated and the crushing of the remains of branches generated outside the wetland have been managed by the company Sefocat, which has carried out it with a forestry tractor with a winch and a hammer crusher without entering the peaty system at any time, to avoid degrading it.

The technical supervision has been carried out by the managing body of the Alt Pirineu Natural Park, and the scientific monitoring has been carried out by the research group GEOVEG of the University of Barcelona.