The 70s were notable for a number of things. Flared trousers, gull-winged shirts, kipper ties, and in forestry – ploughing. The aforementioned dubious fashion items are making a comeback; and so too is ploughing, and similar forms of unsightly forestry cultivation.
To get a flavour of the forest industry enthusiasm for it, check out Tilhill’s website. Many of us within the forest sector thought we had seen the last of this, however it is clearly firmly back on the agenda. And it appears to have happened without an obvious prior policy announcement explaining why. In agriculture, efforts are being made to limit cultivation, so as to reduce greenhouse gas emissions – so it seems odd that in forestry a trend has appeared in the opposite direction.
Reliance on intensive cultivation is a recurring theme in forestry. We did it spectacularly from the 1960s to the 1980s and were rewarded with plantations that blew down prematurely costing the industry millions, along with sediment in lochs and rivers and, as we now know, large-scale release of soil carbon.
Similarly, there are thousands of hectares of new native woodland established on over-enthusiastic excavator mounds, with their accompanying mini tank traps that will last for centuries. These undermine the whole effort to produce an attractive, natural-looking woodland. On restock sites, we send in mechanical excavators to lumber round and trench-mound the sites, usually taking place hard on the heels of soil disturbance, and its attendant carbon release, during harvesting and extraction.
It seems that UK foresters, uniquely, are hardwired to plant trees only on radically upturned soil, fearing that anything less will end in failure. We may have got wise to avoiding some of the worst types of excessive cultivation we carried out in the 1960-80s. However one can’t help wondering what the balance is between the benefits and impacts of cultivation – particularly this new wave of ploughing for woodland creation.
Helpfully the Forestry Commission has consulted on a document “Cultivation guidance for upland productive woodland creation sites” and this gives a concise list of the environmental costs of cultivation, namely:
- Greenhouse gas release through oxidation of soil organic matter;
- Water pollution caused by sediment loss and increased runoff;
- Damaged soil structure and increased risk of windblow, erosion or landslip;
- Leaching of nutrients and contaminants.
We would add to that list the fact that the sight of a ploughed up or trench-mounded Scottish hillside is one of the worst adverts for the forestry profession.
Lined up on the benefits side is the fact that some cultivation and drainage is a damned fine thing and can help young trees overcome the cold glaur of a Scottish hillside, and so get away from weeds and other problems that beset young trees. So, one question is – what is an appropriate level of cultivation?
The new FC Guidance helpfully emphasises that “Applications [to plant trees] with cultivation techniques that risk an unacceptable impact on the local site and provide no additional benefits compared to a less intensive technique are unlikely to be approved.” To which FPG says “amen”, and in our view that simply rules out ploughing. We also think it rules out all forms of cultivation for native woodland establishment except the shallowest inverted mounding, screefing and patch scarifying. On restock sites we need to move away from trench mounding and back towards planting at stump and scarifying.
Patch scarifying and mounding disturb about 100-200 m3 of soil per hectare, whereas ploughing and continuous scarifying disturb roughly 6 times as much, with deep ploughing turning over an immense 1500 m3. However, in the ‘boys with toys’ world of forestry cultivation, the more intensive methods like ploughing are often cheaper than the alternatives. Hence their popularity among the owners of woodland creation sites and their forestry company advisors. This does not seem to be in the spirit of either the UK Forest Standard or Scottish Government’s recent emphasis on Sustainable Forest Management.
The second important point is that we are rapidly entering a world where every use of fossil fuel is going to be scrutinised then, as far as possible, eliminated. Ditto any activity that leads to avoidable carbon emissions, including those from soils. So, for example, we now have a date for ceasing the production of fossil-fuel road vehicles and we are heading for net carbon zero by 2045. Seen from this perspective, the practice of sending massive excavators and forestry tractors to lumber over square kilometres of forest land is absurd, and it is only a matter of time before it is laughed out of court. So what is needed is some serious innovation. The key question becomes – what sorts of reasonably effective cultivation can be done with lightweight kit, which could become electric or hydrogen powered in the near future?
There are many situations where trees will get away fine with relatively small amounts of cultivation. Trees of all types will establish well on most brown earth and many surface water gleys, as stands of conifers planted on private estates in the 1930s and 1940s attest, these standing up better to windblow than their later ploughed counterparts. We all know that restocking can be done without trench mounding. Some of the best new native woodland was established with no more than hand screefing, sometimes on quite challenging sites, such as the National Trust for Scotland’s wood at Dalness in Glen Etive. Forest Enterprise established much of their prize-winning native woodlands at Loch Katrine with shallow, inverted mounding.
We clearly need to step up to the task of promoting “energy efficiency” in our activities – in the same way as in other industrial sectors such as housing, where this is seen as a major contribution to climate change measures. This could start with developing low energy, low impact cost-effective forms of cultivation and drainage. That is the future, not a return to the 1970s. Unfortunately we have rather too many in our ranks for whom excessive cultivation is carried out simply out of habit; or because they are fixated on rapid establishment and the survival of trees to year 5, with all the wider problems conveniently overlooked.
You can tell them by their attire: flared trousers, gull-winged shirts, and kipper ties.