Impacts of climate change on the establishment, distribution, growth and mortality of Swiss stone pine (Pinus cembra L.)

Abstract

© iForest -Biogeosciences and Forestry IntroductionFuture impacts of global climate change such as predicted increases in annual air and surface temperatures and variations in pre cipitation will cause significant alterations in forest ecosystems (Eastaugh 2008). Impacts of these changes will be proportionally more perceptible at high elevations (Bensiton et al. 1997).In timberline ecotones near the upper limit of closed forests tree growth, forest structure and forest dynamics are mainly temperaturedriven (Tranquillini 1979, Innes 1991, Körner 1998. The sensitivity of these biomes to climate variability is high and thus of special interest for understanding the ef fects of global change.Swiss stone pine (Pinus cembra L.) is dis tributed in timberline ecotones across Europe from the Carpathian Mountains to the French Alps (Polunin & Walters 1986, Ulber et al. 2004. During several hundred years of hu man activities such as alpine farming or tim ber extraction Swiss stone pine was often eliminated and therefore restricted to stands on inaccessible slopes exposed to the North (Holtmeier 1966, Motta & Nola 2001, Höhn et al. 2009). In recent decades, socio-eco nomic and silvicultural changes have fa voured the establishment of Swiss stone pine (Motta et al. 2006). This five-needled conifer tree is well adapted to the harsh subalpine climate conditions in the Central European Alps (Ulber et al. 2004) and is often asso ciated with mountain pine (Pinus montana Miller), Scots pine (Pinus sylvestris L.), European larch (Larix decidua Miller) and Norway spruce (Picea abies L. Karst). In the continental subalpine forests of the Central Alps with relatively low rainfall and mean annual temperatures below 1.5 °C (Ellenberg 1996), stands develop from early-successio nal stages dominated by mountain pine to a late-successional stage dominated by Swiss stone pine and European Larch (Risch et al. 2003, Höhn et al. 2009).This review will summarize the evidence of Swiss stone pine responses to climate change at the timberline ecotone. The review will consider all life stages, and possible dis tribution shifts of Swiss stone pine popula tions in the future will be discussed. Seedling establishmentSwiss stone pine is a monoecious, wind pollinated species which reaches reproduc tive maturity at 40-60 years of age (Ulber et al. 2004) with good seed production years occurring on average twice in ten years (Mattes 1982). Seed production is especially sensitive to climate because important deve lopmental processes such as the initiation of flower and cone primordia, meiosis and the release of pollen depend to a large degree on climatic variables (Pigott 1992). The tempo ral dynamics of seed production and the in fluence of climate change on seed produc tion of Swiss stone pine have however not been comprehensively investigated to date.The wingless Swiss stone pine seeds are mainly dispersed by the European nutcracker bird (Nucifraga caryocatactes L.). Swiss stone pine seeds are the main food source for European nutcrackers, and those bird...

Is land abandonment affecting forest dynamics at high elevation in Mediterranean mountains more than climate change?

“…This patchy process is influenced by the presence of former agricultural structures, such as terraces or walls, and crops, including fruit trees. This secondary succession is currently accelerating in many areas of the Italian Peninsula, acutely in mountainous areas (Motta et al 2006;Boden et al 2010). The same is happening in the central Apennines, where 2400 m a.s.l.…”

“…Industrialization processes of Europe during the nineteenth and twentieth centuries have triggered deep socioeconomic shifts, including rural exodus and declines of traditional practices based on smallscale agriculture, pastoralism and forest resource utilization (Blondel & Aronson 1999). These changes in land use were characterized by the abandonment of marginal areas, generally situated in the mountains, where land-cover change, grazing cessation and switch from habitual forest resources to other construction material or fuel type have transformed the landscape patterns deeply (Debussche et al 1999;Boden et al 2010).…”

“…Yet, rising temperatures have increased the productivity and survival of trees in mountain environments (Paulsen et al 2000;Motta & Nola 2001), with a resulting expansion of woodland mosaic in the Alps (Chauchard et al 2007). In Mediterranean mountains, instead, patterns of land abandonment and livestock grazing superimpose to the effect of climate change, and therefore these observations have to be reframed in a context of land-use change (Poyatos et al 2003;Boden et al 2010).…”

“…Despite the relatively high annual precipitation in the study area, regular and prolonged summer droughts point to the Mediterranean mark of this forest ecosystem. The high solar radiation coupled with high soil permeability due to karst and fissuring of limestone may result in high evaporative water loss and low water-holding capacity (Anfodillo et al 1998;Boden et al 2010). Dirnbö ck et al (2003 suggested a considerable range expansion of mountain pine at only moderate levels of temperature increase, throughout most of the north-eastern calcareous Alps.…”

Alternative stable states in mountain forest ecosystems: the case of European larch (Larix decidua) forests in the western Alps

“…Silvopastoral activities eliminated Pinus cembra during centuries, to the point that it was almost removed from the alpine forest landscape (Holtmeier 1990(Holtmeier , 1994Boden et al 2010). However, due to land abandonment, cembran pine is gradually replacing larch at high elevation, although the succession is slow and mixed larch-cembran pine stands can persist for centuries (Motta and Nola 2001;Motta and Lingua 2005;Motta et al 2006).…”