Increased management is needed to reduce hazards and control pests in forests due to climate change.
The projected shift of precipitation into the wintertime will more often lead to drought stressed trees in summer. Due to its shallow rooting system spruce is especially prone to drought stress. Higher temperatures not only favour tree growth but also the development of pest species such as the European spruce bark beetle (Ips typographus). Drought stressed trees become susceptible to bark beetles and are easily colonised by these pests. A greater supply of weakened spruce trees and increased populations of bark beetles will lead to higher tree mortality resulting in stands with dead trees. In addition, the frequency and intensity of severe storms may increase. This disturbance can result in large-scale windthrow providing defenceless timber in which bark beetle populations can build up and infest adjacent living spruce stands. Such outbreaks are, therefore, likely to become even more frequent in the future.
Since sanitation cutting of infested trees is often unprofitable depending on the timber market, there is little financial incentive to remove such spruce trees. Moreover, forest managers often lack the capacity to cut and remove all the infested trees in time to prevent further spread of the pests. This means more dead trees are left standing for longer periods, which present falling hazards. Time pressure and workload on forest managers will continue to be increase as more hot and dry summers occur and abundant supply of spruce is available in Swiss forests. Even with sanitary measures and subsequent natural regeneration, it takes a long time until a forest with more drought-adapted tree species emerges. In the meantime, forest recreationists can expect to encounter unshaded patches wherever infested trees have been cleared.
Last modification 11.11.2021