Early action and more investments are needed to respond to the threats of climate change on the world's forests. It will probably cost less to adjust forest management strategies immediately to the impacts of climate change than to react to the aftermath of climate-inflicted damage, according to the UN Food and Agriculture Organisation.

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Early action will also help to improve the livelihoods and food security of local communities around the world. Decreased forest ecosystem services, especially water-cycle regulation, soil protection and the conservation of biodiversity, may affect millions of people in rural areas, who use forests for food, fuel, timber, medicines and income. For example, 4-5 million women in West Africa earn about 80 percent of their income from the collection, processing, and the marketing of nuts harvested from shea trees.

"Climate change is impairing the ability of forests to deliver critical goods and ecosystem services. Forest managers urgently need to respond to a wide range of threats posed by climate change. These guidelines will help them to assess and monitor the climate-change impacts applicable for each type of forest and region," said Simmone Rose, FAO's Forestry Officer.

"For example, Asia is affected by the increase of extreme weather events, in some parts of Latin America rising temperatures and lower rainfall have resulted in the increased incidence of forest fires, whereas more severe droughts in Africa in recent years threaten already scarce water resources in the region," she said.

The FAO has produced a set of guidelines for forestry managers, which it hopes will adjust forest management practices in response to climate change.

Water availability and quality

Climate change is altering precipitation and runoff patterns; in the UK, this means rainfall patterns are shifting towards less frequent but more intense rainfall, though the picture is different all over the world. Some regions are experiencing reduced precipitation and drought, whilst others are suffering from more heavy rainfall.

In areas where rains have become more intense, erosion and flooding are becoming major problems. FAO said forests in upper watersheds reduce storm runoff and erosion, and forests adjacent to water bodies help stabilise river banks, reduce the amount of sediments entering the water and filter pollutants.

Forests therefore have the capacity to regulate water availability and quality, but the Rome-based UN organisation warned this will be compromised if they themselves are negatively affected by climate change. Maintaining healthy forests and restoring degraded ones in the watershed will help to reduce erosion, increase slope stability and to ensure the availability of clean and regular water supplies. 

Fire prevention: enlisting local communities

The risk of forest fires is expected to increase with higher temperatures and decreased precipitation due to climate change.

In regions such as Southern Europe, this will be of particular concern; in 2012, forest fires burned in Spain which temporarily overwhelmed emergency services that had been left reeling from austerity packages. According to FAO's new guidance, promoting landscapes that impede fire spread and forest species that are fire-resistent are important strategies in fire management

Agricultural burnings should take place before the peak of the dry season. This type of management is often beyond the scope of forest managers and they are encouraged to engage local communities in fire management.

Pests and diseases

Climate change, particularly extreme weather events, can affect forest pests and the damage they cause directly, by altering their reproduction and spread, and indirectly by changing the abundance of competitors, parasites and predators.

Prevention measures may include the selection of species and varieties to suit the local conditions and thinning practices that reduce pest populations and favour natural enemies. The careful monitoring of pest populations will help determine when control activities are needed.