Forest growth (CLIM 034) - Assessment published Sep 2008
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Climate change (Primary topic)
Typology: Descriptive indicator (Type A – What is happening to the environment and to humans?)
- CLIM 034
Key policy question:
- In much of continental Europe, the majority of forests are now growing faster than in the early 20th century.
- A changing climate will favour certain species in some forest locations, while making conditions worse for others, leading to substantial shifts in vegetation distribution.
- The distribution and phenology of other plant and animal species (both pests and pollinators) are likely to change, leading to further alterations in competitive dynamics in forests that will be difficult to predict.
- Periods of drought and warm winters are increasing pest populations and further weakening forests.
Current (2000) and projected (2100) forest coverage in Europe
Note: Modelled to evaluate the change of habitat suitability coverage of the ten most dominant European Forest Categories (EEA, 2006), used IPCC SRES A1B scenario and NCAR CCM3 model.
Casalegno, S.; Amatulli, G.; Bastrup-Birk, A.; Houston, T., 2007. Modelling Current and Future Distribution of European Forest Categories. Proceedings of the 6th European Conference on Ecological Modelling: Challenges for ecological modelling in a changing world: Global Changes, Sustainability and Ecosystem Based Management. 2730 November 2007. Trieste, Italy.
For many centuries, most European forests were overexploited. Growth rates were reduced and biomass stocks were depleted until the middle of the 20th century, when growth rates started to recover (Spieker et al., 1996). Much of this increase can be attributed to advances in forest management practices, genetic improvement and, in central Europe, the cessation of site-degrading practices such as litter collection for fuel. It is also very likely that increasing temperatures and CO2 concentrations, nitrogen deposition, and reduction of air pollution (SO2) have had a positive effect on forest growth. Trees have long been known to respond to changes in climate: variations in tree-ring widths from one year to the next are recognised as an important source of climatic information.
Several studies have already noted changes in dates of budburst and therefore longer growing seasons in several species, shifts in tree-line, and changes in species distribution. A north-east shift of forest categories has already been observed for European forest species (Bakkenes et al., 2002; Harrison et al., 2006).
Tree growth is controlled by complex interactions between climate- and non-climate-related factors, with forest management also having a significant effect. Possible future responses of forests to climate change include increased growth rates, tree-line movements, changes to forest growth, phenology, species composition, increased fire incidence, more severe droughts in some areas, increased storm damage, and increased insect and pathogen damage (Eastaugh, 2008). Taken together this is likely to lead to a changed pattern of forest cover. Simulation of the IPCC SRES A1B scenario for the period 2070-2100 shows a general trend of a south-west to north-east shift in suitable forest category habitat (Casalegno et al., 2007).
Although climate change is projected to have an overall positive effect on growing stocks in northern Europe, negative effects are also projected in some regions (e.g. drought and fire pose an increasing risk to Mediterranean forests), making overall projections difficult.
Change of habitat suitability coverage of European Forest Categories
provided by Joint Research Centre (JRC)
More information about this indicator
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