Land‐use changes as major drivers of mountain pine (Pinus uncinata Ram.) expansion in the Pyrenees

Abstract

Aim To assess the spatial patterns of forest expansion (encroachment and densification) for mountain pine (Pinus uncinata Ram.) during the last 50 years at a whole mountain range scale by the study of different topographic and socioeconomic potential drivers in the current context of global change.Location The study area includes the whole distributional area of mountain pine in the Catalan Pyrenees (north-east Spain). This represents more than 80 municipalities, covering a total area of 6018 km 2 .Methods Forest cover was obtained by image reclassification of more than 200 pairs of aerial photographs taken in 1956 and 2006. Encroachment and densification were determined according to changes in forest cover, and were expressed as binary variables on a 150 ¥ 150 m cell-size grid. We then used logistic regression to analyse the effects of several topographic and socio-economic variables on forest expansion. ResultsIn the period analysed, mountain pine increased its surface coverage by 8898 ha (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 in mountain pine expansion, as encroachment rates were higher in municipalities with greater population losses or weaker primary sector development. Main conclusionsThe spatial patterns of mountain pine expansion showed a good match with the main patterns of land-use change in the Pyrenees, suggesting that land-use changes have played a more important role than climate in driving forest dynamics at a landscape scale over the period studied. Further studies on forest expansion at a regional scale should incorporate patterns of land-use changes to correctly interpret drivers of forest encroachment and densification.

Complex climate constraints of upper treeline formation in the Pyrenees

“…As in most European mountains, Pyrenean treelines have been historically altered and shifted downwards due to human activities such as logging and grazing (Améztegui et al 2010). However, the recent abandonment of traditional forest uses and climate warming has boosted the invasion of alpine grasslands by mountain pine and the establishment of young trees forming a climate-driven treeline Gutiérrez 2002, 2004).…”

Forest structure of Mediterranean yew (Taxus baccata L.) populations and neighbor effects on juvenile yew performance in the NE Iberian Peninsula

“…In the foothills of the Pyrenees and on the northern aspect of the Mediterranean Coastal ranges, Submediterranean conditions were also common, according to the definition assigned by Ozenda (1994) as the area with climatic characteristics between those of typically Mediterranean and temperate European climate area (see Sánchez de Dios et al, 2009 for further details). In the NE Iberian Peninsula, and similarly in other Mediterranean regions in Europe, traditional forest activities were abandoned during the second half of the last century, leading to increased forest density (Lasanta-Martinez et al, 2005, Ameztegui et al, 2010 especially in the Coastal range, with multi-stemmed stump structures. variety of forest communities (Cortés et al, 2000;Piovesan et al, 2009).…”

Estado comparativo de las masas de <i>Pinus uncinata Ram.</i> potencialmente protectoras frente a aludes de una zona de Andorra y Cataluña

“…La mayor presencia del tipo B en Cataluña evidenciaría que el proceso de expansión de la especie debido al descenso de las actividades antrópicas (Améztegui et al, 2010) (E y L) y el menor número de algunos de los mejores (G y H), podría obedecer a las secuelas de las cortas abusivas de los siglos XIX y XX (González, 2008), no registradas con la misma intensidad en Andorra. La presencia notable en Cataluña de estructuras capitalizadas en existencias volumétricas (tipo F), ausentes sin embargo en la zona estudiada de Andorra, apuntan por el contrario a una preocupante falta de tratamientos selvícolas en esos rodales durante los últimos decenios.…”

“…El pino negro ocupa en España cerca de 60.000 ha (55,9% monoespecíficas), con las mejores calidades productivas localizadas entre los 1.400-1.600 m de altitud en umbrías y 1.800-2.200 m en solanas, y donde solamente el 23,3% de las masas monoespecíficas se encuentran en espesuras medias y altas (Calama et al, 2004). El 75% de esa extensión corresponde a Cataluña (45.000 ha), advirtiéndose en ciertas comarcas una franca expansión (en superficie y espesura) desde el año 1956 (Améztegui et al, 2010).…”