The Guardian recently reported on a study by Dr Adam Pellegrini of Cambridge University that has highlighted that wildfires are impacting on the ability of forests to capture carbon due to changes in tree density and size. Given that trees are increasingly seen as a natural climate solution (or Nature-based Solution (NbS)), the more we can understand the consequences of afforestation (and re-forestation) the better.
Increasing tree planting globally has been highlighted as affecting albedo (with consequent climate feedback impacts), biodiversity, carbon sequestration, groundwater recharge and risk of wildfire. To be an effective NbS, any disbenefits need to be understood and compared to the benefits on a site-by-site basis. In the UK, this has led to calls for the “right tree in the right place” approach to ensure that risks associated with impacts on biodiversity or carbon emissions are considered.
Arguably, this now has another dimension – fire-adaptation: “Planting trees in areas where trees grow rapidly is widely promoted as a way to mitigate climate change. But to be sustainable, plans must consider the possibility of changes in fire frequency and intensity over the longer term.” Planting trees near our valuable peatland and heathland may therefore be considered a risk given the prospect of climate change – not only in terms of the risk of tree-fuelled wildfire damaging soil carbon but also the stability of that carbon stock, as allowing trees to grow on carbon-rich soils can result in a net loss carbon.
Also of interest to me was a paragraph towards the end of the report, which stated: “Fire cycles are a positive and necessary part of some landscapes, however, ensuring a diversity of plants and animals. If fires are suppressed by people in savannah systems, the species-rich grassland can be rapidly covered by a less diverse treescape.” Is savannah (or peatland) biodiversity a luxury we cannot now afford? Maybe it is if a) climate mitigation is always the main effort and b) treescapes capture and store more carbon that the savannah (peatland).
We, and others including Dieter Helm, believe there must be some places where climate and unique biodiversity are balanced and neither is primus inter pares. This is why vegetation management is important in our upland landscapes. We need to actively manage our peatland and heathland landscapes, through grazing, burning, cutting and scrub clearing, to mitigate the natural succession processes that occur.
Secondly, increasingly research in the UK suggests these processes do not damage Sphagnum thereby degrading blanket bog. GWCT research written up this year has provided further evidence to suggest that prescribed burning at appropriate time intervals can help peat-forming vegetation by reducing competition from heather. The weight of scientific evidence is shifting – see Matt Davies’ recent Twitter blast!
The managed burning of our uplands, in accordance with ecologically driven rotations, should be regarded as a cultural practice, akin to the fire practices exhibited by indigenous peoples in other parts of the globe (see our blog Wildfires – fighting fire with fire?), and a positive and necessary part of our upland landscape. Would regarding it as such make it more acceptable?