Incorporating results from forest hydrology studies in water policies can help avoid uncertainty and confusion caused by the current difficulties in transferring research findings to different countries and regions, varying forest types and species and diverse forest management regimes. In addition, institutional mechanisms to enhance synergies in forests and water administrations are needed at national and regional levels.
These key messages to the decision makers were formed during the international conference “Water and Forests: a convenient truth?” held in October 2008. The conference gathered together renowned scientists to addressed the topic not only at a global level, but also highlighting the situation in the Mediterranean area.
The conference agreed that it is clear that forests are linked to water yield. Forests use more water than shorter types of vegetation because of their higher evaporation rates. Water use efficiency differs between forest species; and soil water availability fluctuates at each stand of trees. Canopies protect the ground from runoff which also means higher interception. Root systems influence the groundwater recharge.
Consequently, forest management practices should be adjusted to reach desired impacts on water by using a mix of different tree species and of varying ages, or by designing forest structure and open areas (e.g. from harvesting). Follow up of such measures is required as it is essential to determine the influences of forest management actions in water at each stand.
One of the other main findings shows that global climate models predict marked changes in seasonal snow- and rainfall with more uncertainties than in temperatures. Also, they forecast a significant decrease in rainfall in the Mediterranean basin and an increase of rainfall during in winters in Central and Northern Europe. Therefore, when designing large-scale forest plantations for C sequestration, water shortage should not be accentuated. Shade provided by riparian forests may help reduce thermal stress to aquatic life as climate warming intensifies.
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