New Article: Unraveling the role of light and biotic interactions on seedling performance of four Pyrenean species along environmental gradients

 In a new article, recently published in Forest Ecology and Management, we have assessed the role of factors acting at fine spatial and temporal scale (i.e. microsite level) on the dynamics of montane and subalpine forests of the Pyrenees. We established a set of experimental mixed plantations along elevational and environmental gradients using four common species in the area: Scots pine (Pinus sylvestris), mountain pine (Pinus uncinata), silver fir (Abies alba) and birch (Betula pendula), and monitored seedling performance over 4 years. 

Short events of extreme climatic conditions (drought, freezing) had a strong impact on juvenile tree mortality, mainly affecting the species growing further from their mean elevational range. Moreover, we found that positive plant-plant interactions were markedly species-specific and varied with elevation. They were in particular present in the subalpine sites, modulating the effects of unfavorable climatic conditions for species growing above their current limits. In contrast, we did not detect any positive nor negative effect of shrubs on the plants established at the low-elevation sites, suggesting that, in such conditions, the net effect of above- and belowground interactions is neutral. In these sites, the herbaceous cover was found to negatively affect A. alba survival, probably due to competition for water. Finally our results show a positive effect of canopy closure on silver fir survival.

 In summary, our study underlined that plant-plant interactions and other factors driving at fine temporal and spatial scales can have a strong impact in the dynamics of montane-subalpine forests of the Pyrenees. These processes acting at microsite level should thus be explicitly considered when implementing management plans to contend the future impacts of climate change in these areas.

Ameztegui, A; Coll, L (2013) Unraveling the role of light and biotic interactions on seedling performance of four Pyrenean species along environmental gradients. Forest Ecology and Management 303: 25-34.

The study area, in the Cadí Range, Catalonia (Photo: Aitor Ameztegui)

New Article: "Environmental campaigns against forest companies: What are the campaigns trying to achieve?"

Environmental campaigns against forest companies: What are the campaigns trying to achieve?
Forest Systems.(2012) 21 (2): 247-258.
Authors: Gritten, D., Gonzalez-Olabarria, J.R., Mola-Yudego, B., Dominguez, G.


Campaigns by environmental non-governmental organisations (ENGOs) can have far reaching consequences in determining the policies of governments and corporations. This paper examines campaigns targeting forestry companies to determine what makes a successful campaign.

New article: Understory light predictions in mixed conifer mountain forests

In a new article published in the journal Forest Ecology and Management, members of FiDBosc, led by Aitor Ameztegui, have highlighted the importance of explicitly considering aspect when modeling the dynamics of mountain forests.

Predicting light availability in forest understory is a key step in the modeling of forest dynamics. In mountain forests, aspect is often the main source of environmental variation, and so aspect-induced differences in crown geometry and transparency can sharply affect light transmission through the canopy and modify understory light predictions. However, this effect has almost been ignored to date. 

This study, in which we collaborated with researchers from the Université du Québec à Montreal (UQÀM) and the  Spanish National Research Council (CSIC), has shown that the effect of slope aspect on tree crowns is highly species-specific. Aspect influences crown geometry, transparency and irregularity of all the studied species (silver fir, Scots pine and mountain pine), and therefore the observed changes in crown openness may be a combined effect of changes in total leaf area and patterns of leaf distribution. The observed species-specific variation in crown geometry and openness with aspect resulted in sharp differences in understory light predictions that were large enough to warrant explicit consideration when studying and modeling the ecological processes driving the dynamics of these forests.

Ameztegui, A, Coll, L, Benavides, R, Valladares, F, & Paquette, A (2012). Understory light predictions in conifer-mixed forests: the role of aspect-induced variation in crown geometry and openness Forest Ecology and Management, 276 (52-61) DOI: 10.1016/j.foreco.2012.03.021

New article: Modelling natural disturbances in forest ecosystems: a review

In this study, authors from different fields and institutions review the wide variety of approaches for modelling natural disturbances in forest ecosystems, adressing the full spectrum of disturbance modelling from single events to integrated disturbance regimes.

Seidl, R., Fernandes, P.M., Fonseca, T.F., Gillet, F., Jönsson, A.M., Merganičová, K., Netherer, S., Arpaci, A., Bontemps J.D., Bugmann, H., González-Olabarria, J.R., Lasch. P., Meredieu, C., Moreira, F., Schelhaas, M.J., Mohren, F. 2011. Modelling natural disturbances in forest ecosystems. Ecological Modelling . 222: 903-924

New article: Advanced models for the risk of storm and fire to European forests

This article is part of an special issue about "Trends in modeling to address forest management and environmental challenges in Europe".

The aim of this paper is to discuss the different recently developed empirical and mechanistic modelling approaches for assessing the risk of wind and fire damage to forests. Additionally the work will explore possible ways to integrate these approaches, including feedback mechanisms, into growth and yield models and decision support tools used in forestry.

Hanewinkel, M; Peltola, H; Soares, P; Gonzalez-Olabarria, JR (2010) Advanced models for the risk of storm and fire to European forests and their integration into simulation and decision support tools. Forest systems 19 (SI), 30-47.

New article: Forest vegetation management under debate: an introduction

This article constitutes the guest editorial of the special issue of the European Journal of Forest of January 2011 that compiles the main articles presented in the final conference of the COST action E47 ‘‘European Network for Forest Vegetation Management (FVM): Towards Environmental Sustainability’’.

In this article, the authors discuss about (i) the existing differences between continents with regard to the preferred methods for control herbaceous and woody competitors and (ii) the main inconsistencies that are found in the literature about FVM.

Finally, they introduce the reader to the different articles on FVM that are published in this issue.

The article can be download (PDF file) in the following link:

Ammer C., Balandier P., Scott-Bentsen N., Coll L., Löf M. (2011) Forest vegetation management under debate: an introduction. European Journal of Forest Research 130: 1-5.

New article: Wind and snow damage in the Pyrenees pine forests: Effect of stand attributes and location

Wind and snow-induced damage have been analyzed at stand level for three pine forests in the Central-Eastern Pyrenees (Pinus nigra Arn. salzmanii, Pinus sylvestris L. and Pinus uncinata Ram.). Stand-level models have been then developed for the most affected two species, Pinus sylvestris L. and Pinus uncinata Ram., to describe damage severity. The models were based on data from national forest inventory plots. They included variables related to the spatial location and structure of the stands, being validated using a sub-set of the database (25% of the plots randomly selected). Mountain pine forests (Pinus uncinata Ram.) were the most heavily affected by wind and snow disturbances.

For both mountain and Scots pine species, topographic exposure and the severity of the local storm regime had an important effect on the degree of damage. Stand’s resistance to wind and snow was found to be dependent on the combined effect of basal area and mean slenderness of the dominant trees. For a given slenderness ratio, damage increased strongly in lower-density stands, particularly in stands with basal areas below 15 m²/ha. Stand structure was particularly important to define the resistance of Scots pine stands, which presented a higher vulnerability to wind and snow under higher degree of even-agedness.

The models presented in this study provide empirically-based information that can be used to implement silvicultural practices to minimize the risk of those forests to suffer wind and snow-related damages.


Martín-Alcón, S; González-Olabarria, J.R.; Coll, L. (2010). Wind and snow damage in the Pyrenees pine forests: Effect of stand attributes and location. Silva Fennica 44 (3) : 399-410.

New article: Land-use changes as drivers of mountain pine expansion

Aitor Améztegui and Lluís Coll, from FiDBosc, recently got a paper published in Global Ecology and Biogeography about the patterns and drivers of mountain pine expansion in the Pyrenees.

The aim of this study was to assess the spatial patterns of forest expansion (encroachment and densification) for Mountain pine (Pinus uncinata Ram.) during the last 50 years in a whole mountain-range scale by the study of different topographic and socio-economic potential drivers in the current global-change context. Forest cover was obtained by image reclassification of more than 200 pairs of aerial photographs taken in 1956 and 2006, covering the whole distributional area of Mountain pine in the Catalan Pyrenees (NE Spain). This represents more than 80 municipalities and a total area of 6,018 km2. Encroachment and densification were determined according to changes in forest cover, and were expressed as binary variables on a 150x150m cell-size grid. We then used logistic regression to analyze the effects of several topographic and socio-economic variables on forest expansion.

In the period analyzed, Mountain pine increased its surface coverage by 8,898 hectares (an increase of more than 16%). Mean canopy cover rose from 31.0% in 1956 to 55.6% in 2006. Most of the expansion was found on north-facing slopes and at low altitudes. Socio-economic factors arose as major factors of Mountain pine expansion, as encroachment rates were higher at municipalities with greater population losses or weaker primary sector development.

Therefore, the spatial patterns of Mountain pine expansion highly matched the main patterns of land-use change in the Pyrenees, suggesting that land-use changes have played a more determinant role than climate in driving forest dynamics at landscape scale over the period studied. Further studies on forest expansion at regional scale should incorporate patterns of land-use changes to correctly interpret drivers of forest encroachment and densification.

Améztegui, A; Brotons, L; Coll, L. (2010). Land-use changes as major drivers of mountain pine (Pinus uncinata Ram.) expansion in the Pyrenees. Global Ecology and Biogeography 19 (5) : 632-641.

New article: Predicting understory maximum shrubs cover in Mediterranean forests

Predicting understory maximum shrubs cover using altitude and overstory basal area in different Mediterranean forests

In some areas of the Mediterranean basin where the understory stratum represents a critical fire hazard, managing the canopy cover to control the understory shrubby vegetation is an ecological alternative to the current mechanical management techniques. In this study, we determine the relationship between the overstory basal area and the cover of the understory shrubby vegetation for different dominant canopy species (Pinaceae and Fagaceae species) along a wide altitudinal gradient in the province of Catalonia (Spain). Analyses were conducted using data from the Spanish National Forest Inventory. At the regional scale, when all stands are analysed together, a strong negative relationship between mean shrub cover and site elevation was found. Among the Pinaceae species, we found fairly good relationships between stand basal area and the maximum development of the shrub stratum for species located at intermediate elevations (Pinus nigra, Pinus sylvestris). However, at the extremes of the elevation-climatic gradient (Pinus halepensis and Pinus uncinata stands), stand basal area explained very little of the shrub cover variation probably because microsite and topographic factors override its effect. Among the Fagaceae species, a negative relationship between basal area and the maximum development of the shrub stratum was found in Quercus humilis and Fagus sylvatica dominated stands but not in Quercus ilex. This can be due to the particular canopy structure and management history of Q. ilex stands. In conclusion, our study revealed a marked effect of the tree layer composition and the environment on the relationship between the development of the understory and overstory tree structure. More fine-grained studies are needed to provide forest managers with more detailed information about the relationship between these two forest strata.

Coll, L., Gonzalez-Olabarria, J.R. Mola-Yudego, B., Pukkala, T., Messier C. (2010) Predicting understory maximum shrubs cover using altitude and overstory basal area in different Mediterranean forests. European Journal of Forest Research. DOI 10.1007/s10342-010-0395-y.

New article: Mapping the expansion and distribution of willow plantations for bioenergy in Sweden

Mapping the expansion and distribution of willow plantations for bioenergy in Sweden: Lessons to be learned about the spread of energy crops

Where and when farmers will adopt new energy crops is a key issue for the proper development of a country’s energy strategy on renewables based in bioenergy. This paper analyses the spread of willow cultivation for bioenergy in Sweden, during the period 1986–2005, linked to the changes in the policies of promotion of wood-energy crops and to the local economic framework. To perform the study, a geostatistic method based on kernel analysis is applied, in order to identify the spatial grouping patterns of growers and plantations, and the areas where cultivation was successful. The analysis of the resulting figures shows that the development of an infrastructure and a market for willow chips are essential pre-conditions for the development of short rotation coppice for bioenergy. The results of this study confirm that probably the most important factor in the location of willow plantations is the existence of consumers that can guarantee a long-term demand for willow chips. The tools and methods presented, and its analysis, can provide a better understanding of the interactions between the biomass producers, the energy consumers and the different local and national actors.

Mola-Yudego, B., Gonzalez-Olabarria, J.R. (2010) Mapping the expansion and distribution of willow plantations for bioenergy in Sweden: lessons to be learned about the spread of energy crops.Biomass and Bioenergy, xxxx, 1 – 7.

Nou article: Els canvis d'usos del sòl i l'expansió del pi negre al Pirineu català (1956-2006)

Al llarg de la segona meitat del segle XX, la superfície forestal arbrada s'ha incrementat considerablement al Pirineu català. En les zones de major altitud, aquesta expansió del bosc s'ha atribuït sovint als efectes del canvi climàtic i la millora que aquest ha exercit en els factors ambientals que determinen la supervivència i creixement dels arbres.

No obstant això, els importants canvis socioeconòmics que ha patit el Pirineu al llarg del segle XX han jugat, així mateix, un paper clau en aquest procés en constituir als antics terrenys de vocació agropastoral zones susceptibles de ser ocupades pel bosc.

Aquest estudi avalua la importància relativa dels canvis en els usos del sòl en el procés d'expansió del pi negre(Pinus uncinata Ram.) en el transcurs dels darrers cinquanta anys.

Podeu descarregar l'article sencer, en pdf, fent click al següent enllaç:

Améztegui,A.; Coll, L. (2009). El canvi d’usos i l’expansió del pi negre al Pirineu català (1956-2006). Catalunya Forestal 100, 15-17