English Abstract Effects of climate change on water relations in forests
were studied using several modelling approaches. Of several models tested,
the FORGRO model had the highest potential for a reliable estimation of
effects of climate change on forests. An evaluation of process-based models
of forest growth showed that several models, including FORGRO, were able to
produce accurate estimates of carbon and water fluxes at several forest
sites of Europe. Responses were in relatively good agreement with the
expected responses obtained by experimental studies, and models were able to
deal with new conditions and explore the likely effects of climate change.
The effect of climate change on forest development was assessed for three
forests stands in The Netherlands using a gap model which was made climate
sensitive by including the effects of climate change scenario IPCC IS92A on
growth (FORGRO results), phenology (FORGRO results), and seed production
(regression analysis). Results showed that climate change is likely to
cause subtle changes rather than abrupt changes in forest development in the
Netherlands, and that forest development on sandy soils in the Netherlands
is not likely to be influenced significantly by climate change over the
coming 50 years. The impact of climate change on the production, nature and
recreation values of forests was studied using a simple economic model, and
showed that response are likely to be relatively small during the first
century, and are related to the successional status of the forest. Linking
of detailed process-based models with gap models enables interpretation of
climate change effects beyond a change in tree growth only, and is an
important tool for investigating the effects of climate change on the
development of mixed forests. The modelling approach presented in this
project (process-based growth models -> gap models -> economic model) is a
useful tool to support policy decisions in the light of climate change and
forests.
