Adapting Scotland’s forests to climate change – changes in tree species suitability

How the suitabilities were calculated

The spatial implementation of Ecological Site Classification (ESC) has been amended to include future climate layers of accumulated temperature (AT), moisture deficit (MD), and wind exposure (DAMS) in a Geographical Information (GI) environment.

In addition, the ESC model has been developed to couple MD and soil moisture regime (SMR) for the summer months. This allows the default values of summer SMR that have been assigned to major soil groups in the baseline climate, to be adjusted in the future climate.

The method for adjustment is based upon the relationship between available water capacity (AWC) and MD, published as Table 6 in Forestry Commission Bulletin 124 – An Ecological Site Classification for Forestry in Great Britain.

Data resolution

It is important that the suitability changes are not interpreted out of context. These are national analyses and should not be used for site or forest-scale planning. They give an indication of the regional trends in suitability. Decisions made at a site or forest block level must take account of the soil type and site conditions.

The model uses coarse resolution data: climate variable resolution is 5 km, and the soil quality data has been interpreted from the digital Soil Survey of Scotland Major Soil Sub-groups, published at a scale of 1:250,000 (Macaulay Institute).

Climatic averages and extremes

Suitability maps have been generated on average climate data. No account has been taken of the impact of extreme events on tree species, other than presenting the high emissions future scenarios as a worst case example. In 2008, we will have access to UKCIP08 climate simulations which are expected to improve our knowledge of the frequency and magnitude of extreme events, such as drought and winter rainfall.

Species suitability maps

Maps are displayed in a new window. File sizes average 40K and dimensions are 440 by 620 pixels.