Tree ranges shifting
Tree ranges shifting
It’s not exactly Macbeth’s dreaded Birnam Wood, but some forests appear to be on the move.
As global temperatures increase, there is likely to be a pattern of migration by some tree species in the northern hemisphere towards higher latitudes and higher elevations.
Purdue University’s Dr Songlin Fei has analysed data on 86 species to investigate the magnitude and direction of their responses to changes in weather patterns over the last 30 years.
He found that 73% of tree species experienced a westward shift, while only 62% had shifted polewards. He suggests the shifts are largely associated with changes in moisture availability rather than temperature.
The impact of the climate on trees can be complicated — different combinations of changes in temperature and precipitation can cause different effects, and different species can have different responses. Previously, resource managers lacked a comprehensive understanding of large-scale climate impacts on forest ecosystems.
Forest managers can now gauge the likely effect of the climate on growing conditions in their specific areas, thanks to an interactive online tool developed by the CSIRO with funding from FWPA.
The free Forest Climate Risk Tool provides information on factors such as the likely periods of drought, rainfall, number of heatwave days, temperatures and fire risk in detail down to a 5km x 5km grid of almost all forested and plantation areas of Australia.
The best available scientific models for climate impact have been used in developing the tool, which enables users to see both the ‘most likely’ result and a range of other possible results for 2030, 2050 and 2070, as opposed to the current situation.
For those interested in looking back, as well as forwards, German researchers have tracked the movement of forest trees, specifically the sycamore maple, after the last ice age.
Sycamore maple (Acer pseudoplatanus) is a broad-leaved forest tree species mainly occurring in mountainous areas of Europe. Like several other important forest tree species, sycamore maple was absent from the area north of the Alps during the last ice age.
However, by about 8000 BCE the sycamore maple had migrated to its current range along two distinct re-colonisation pathways.
One originated from the south-western region of the Alps and moved through the Swiss Jura, north and east, before spreading into Central Germany.
The other originated from the south-eastern part of the Alps and moved west and north, through the Bavarian Forest, before spreading into the north-eastern German lowlands.