Sunday, April 19, 2009

IUFRO Issues Report on Adaptation of Forests to Climate Change

On April 22nd the International Union of Forest Research Organizations (IUFRO) will officially release a report titled "Adaptation of Forests and People to Climate Change – A Global Assessment". The report was developed by a panel of 35 leading forestry scientists, and provides a detailed synthesis of recent research, modeling efforts, and expert opinion for each of the major forest biomes. The report's main conclusion - the carbon regulating roles of forests, are at risk of being reduced by climate change. Forests store 1/2 of the terrestrial carbon and currenty sequester 1/4 of carbon emissions, and thus are a major driver in the global carbon cycle.

Virginia forests are generally expected to see productivity gains from longer growing seasons and elevated CO2. However, species and forest types are expected to shift northward, high mountain forest types may be replaced, new invasive species may pose problems, and stresses from climate change may increase mortality. Increased fire frequency and intensity from more frequent droughts are expected in the states to our south and the effect may extend into portions of Virginia.

A few key points from the global level analysis are summarized below.

The observed effects of recent climate change have been greatest in boreal forests. Increased temperature and longer growing seasons are expected to expand boreal forests north towards the pole and increase growth. On the negative side, increases in fire frequency and epidemic insect outbreaks are also expected, possibly negating any increase in carbon stocks from growth and expansion.

Temperate forests are expected to be the most resilient of the major biomes, especially the humid temperate forests, such as those in eastern North America. Elevated CO2 and longer growing seasons are expected to increase productivity and carbon sequestration. Concerns are raised about biodiversity impacts, the loss of rare forest communities, the spread of invasive species, and stresses to forests as species shifts lag behind climate change.

Increases in fire frequency and intensity have already been observed and attributed to climate change in the semi-arid temperate forests of Western North America, and they are expected to continue. Insect pest epidemics, like the current mountain pine beetle epidemic , are also expected to increase. The net effect may be a reduction in carbon stocks and possibly forest area.

Subtropical forests are expected to experience increased drought, fire extent and fire frequency. Climate change is seen as a major threat to the many subtropical biodiversity hotspots.

Tropical forests are expected to experience productivity gains wherever sufficient moisture is available. Declines in forest area are expected in seasonal dry or otherwise drier tropical areas. Substantial biodiversity losses are expected in the tropics. At the higher end of possible temperature increases, biodiversity losses, mortality and other stresses may negate productivity gains and increase are declines.

Two groups of forest types are noted to be at particular risk: high altitude forests, which have no place to migrate; and mangrove forests, at risk of sea-level rise.

The report argues that sustainable forest management is essential to maximize the ability of forests to adapt to climate change, and, to minimize the environmental, social and economic impacts of climate change.

An executive summary and the full report can be downloaded from the IUFRO website.

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