Category: Forests & trees

According to Ian Dawson, one of the authors of a recent review in Forest Ecology and Management ((Alfaro, R., Fady, B., Vendramin, G., Dawson, I., Fleming, R., Sáenz-Romero, C., Lindig-Cisneros, R., Murdock, T., Vinceti, B., Navarro, C., Skrøppa, T., Baldinelli, G., El-Kassaby, Y., & Loo, J. (2014). The role of forest genetic resources in responding to biotic and abiotic factors in the context of anthropogenic climate change Forest Ecology and Management DOI: 10.1016/j.foreco.2014.04.006)), led by Rene Alfaro, it depends…

The evidence for the negative effects of climate change on forests globally is mounting, with a good example being the outbreak of mountain pine beetle in British Columbia, Canada, believed to be caused by unusually warm winters. It has attacked more than 13 million hectares of lodgepole pine forests over the last decade. Such climate-influenced pest and disease attacks may be particularly problematic for trees, as pests and diseases with shorter generation intervals can evolve more quickly in response to new environmental conditions than their hosts can.

Phenotypic plasticity (the capacity of a particular genotype to express different phenotypes under different environmental conditions), genetic adaptation and seed and pollen migration all have a role to play in responding to climate change, but the speed at which environments alter may be greater than the ability of trees to cope through natural processes, and human help may sometimes be needed. Just as natural responses to climate change depend on genetic resources, so too do human-mediated responses such as altered forest management practices, the facilitated translocation of tree planting material and tree breeding.

Forest managers, however, sometimes question whether interventions formulated to respond to climate change are economically justified, and tropical foresters are likely to consider commercial agriculture and unplanned logging more important production threats. In this setting, appropriate management interventions that are good practice under ‘business as usual’ scenarios are likely to be more effective than those specifically to address climate issues.

For the future, field trials established across different environments are required that allow a better understanding of adaptive variation in tree species, including in drought, pest, disease and fire tolerance and resistance. Another interesting question to address is what role epigenetics (check out the term on Wikipedia) has in responding to climate change by providing a temporary buffer against environmental variability, giving the genome time to ‘catch up’ with change.

When dealing with trees that might only be harvested 100 years after they are planted, estimating the level of future climate uncertainty is obviously crucial. Otherwise, the planting of the wrong species at a site could be catastrophic perhaps decades into the future, as observed when 30,000 ha of maritime pine plantations were destroyed in France during the winter of 1984/1985, following the introduction from the 1940s of non-frost-resistant material from the Iberian Peninsula. New breeding approaches to those currently used are also required, as current methods, with the long generation times of trees, are often too slow to respond to change.