By: Kate Ravilious
Date: August 8th 2016
Source: Environmental Research Web
Say “deforestation” and most of us think of the vast tracts of tropical rainforest being cleared for pasture in the Amazon, or logged for paper production in Indonesia. But research in the New England region of the northeastern US shows that the expansion of affluent suburbs is making a significant but less visible contribution to deforestation in temperate regions of the Western world.
Developed countries are keen on planting trees; since 1990 many surveys suggest that forest area in North America and Western Europe has stabilised, or in some cases even increased by as much as 30%. This reforestation trend appears to follow economic development and has become known as the “forest transition”. Some people have suggested that a similar development in the developing world could lead to “global forest transition”, ending the era of deforestation. But has forest area in the Western world really been increasing?
Small-scale deforestation, such as cutting down a small woodland copse to create a car-park, is not captured by traditional forest inventories. In order to assess whether this small-scale pattern of land-use change has a significant effect, Pontus Olofsson from Boston University and colleagues have used dense time series of high-resolution satellite data, together with probability sampling, to assess changes in land cover and land use between 1985 and 2011 over New England (including the states of Connecticut, Rhode Island, Massachusetts, New Hampshire, Vermont and Maine).
New England is often held as a principal example of a forest transition, with historical widespread deforestation followed by recovery of forestlands as farming activities diminished. However, the data collected by Olofsson and his colleagues suggested otherwise, revealing that forest area has been diminishing throughout the region for the entire study period.
Their results revealed that more than 385,000 hectares of forest – equivalent to 5% of New England's total forest area – has been lost since 1985. “In this case it's almost exclusively driven by residential and commercial development,” said Olofsson. “As affluence and commerce increase, more people are looking for secondary homes, single family homes and larger homes.” And despite people's willingness to plant trees in affluent areas like this, there comes a point when there are no more pastures and farmland available to be abandoned to permit forest expansion.
Despite their small size, the cumulative loss of these pockets of forest matters. “With no forest expansion to counter the deforestation, it turns out that even a small-scale rate of deforestation will have a large impact over time,” said Olofsson, whose findings are published inEnvironmental Research Letters (ERL).
In this case it appears that New England went through a phase of “forest transition” prior to 1985, but since then has entered a secondary phase of deforestation. Other parts of the world are likely to be following similar trajectories, suggesting that forest transition can't be relied on to halt global deforestation. “I think we need to understand that it's not just the tropics that are experiencing a net loss of forest but also parts of the Western world, and that the kind of patterns that we are witnessing have a negative impact on the terrestrial carbon balance in the long run,” said Olofsson.
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Photo source: JR P via Flickr/Creative Commons (CC By-NC-ND 2.0). Photo: © JR P