Are You Good at Silviculture? Part 2
Professor Julian Evans OBE FICFor examines the second and third ingredients needed to answer this vital question.
In Part 1 of this blog, Professor Julian Evans OBE FICFor looked at the first ingredient of good silviculture, namely, knowing well the species we are dealing with. Here he examines the second and third ingredients needed to answer this vital question.
It’s all about interventions as a stand grows
After understanding the species, how you intervene in a stand is the most important tool available in woodland development. An early one is controlling weeds around young trees simply to ensure that the chosen plants (your trees) succeed. Some are more sensitive than others to such competition, some grow slowly and so need this attention for longer, others suffer from specific antagonisms such as spruce and heather.
A quite different intervention arises from the stocking of trees. With successful natural regeneration numbers of saplings may be so high that re-spacing is required. By contrast if the desired tree species are scattered the critical intervention may well be to manage other woody growth present, commonly birch, sallow or woody climbers like clematis which can all swamp the precious stems. This is often done as a ‘cleaning’ and is, arguably, the most critical silvicultural intervention it is dangerous to neglect. It rarely pays for itself, but rarely fails to repay handsomely in the longer term. But you must visit the stand to know it’s needed: successful silviculture can’t be done by computer despite the array of brilliant forestry apps.
The next key intervention is thinning. World-class research by Forest Research in the immediate post-war years showed how to balance removals from a stand with what is left to maximise production over time, so thinning is making the best of a stand’s potential. But it’s not always about yield. For broadleaves grown for timber this means thinning for quality; for other objectives many different regimes can be adopted – and this reveals the foundation underpinning all good silviculture. Knowing what you want to achieve from your stand of trees or forest – your objectives in dull management-speak – is the single most helpful decision you can ever take and silviculture is your handmaiden to achieve them.
Trees don’t live for ever
When taught forestry at Bangor in the 1960s there were lectures on different kinds of rotation – economic, technical, maturity for seeding etc. You can see the ‘plantation as a crop’ all over this concept, but it helpfully raises the point that trees don’t live for ever and thinking about when and how to harvest them is part and parcel of forestry. And, at the same time, thinking about how the woodland will continue must be at the forefront. Silviculture helps us explore the choices from clear felling and replanting to continuous cover systems to woodland that may have been and is again now best worked as coppice or long neglected stems re-pollarded. By ‘silviculture’ I mean our understanding of which of these ways will or will not work, and that comes back to our knowledge of the species we have and the sites they are on.
The fact trees don’t live for ever offers the opportunity of change. The cereal farmer has this every year, the forester can only influence development by degrees as trees grow and increasingly so by how the future stand is brought about. It calls for great skill and great foresight: it calls for great silvicultural knowledge and understanding.
It’s all about the future (and the past)
As a good silviculturist you are shaping the woodland’s future to achieve the best that it can. We are passing on to the next generation forest in better heart than we received it, soil in better condition, stands that are robust and resilient to face the uncertainties of the future: climate change, the continuing scourge of grey squirrels and new aliens, unsustainable deer populations, and all the threats of pests and diseases both new and resurgence of old.
How woodland has been cared for in the past, the decisions we have taken – and the records we have kept – all help build resilience. We are custodians of the nation’s trees, woods and forests. Good silviculture is the tool whereby we will have done our very best in the face of uncertainty.
Our trees and forests have to cope with the many changes in priorities we place on them as fashions and fads come and go and as knowledge is gained. Who would have thought 20 years ago, how valued trees would become for mental and spiritual health, indeed for our general well-being? Knowing what makes them tick, knowing what can and cannot be expected of them calls for the expert, the expert in silviculture. We have a remarkable and precious asset – a national treasure – appreciated by all, and it is entrusted to us.
Would you want to add others or give a different emphasis? Please get in touch at email@example.com
Professor Julian Evans
Professor Julian Evans OBE, FICFor, BSc, PhD, DSc. was formerly professor of Forestry at Imperial College, and before that the Forestry Commission’s Chief Research Officer (S) at Alice Holt Research Station.
He is a Fellow of the Institute of Chartered Foresters and a past President and has written, or was a principal editor of, many technical books on forestry and tree related subjects.
He was one of the three principal editors of the Encyclopaedia of Forest Science (Elsevier 2004). Internationally, Julian has chaired UN Intersessional conferences on the Future of Planted Forests, Chile and New Zealand, and in 1997 he was appointed OBE for “Services to Forestry and the Third World”.
Julian has a long-term interest in the silviculture of broadleaved woodland in the UK and owns woodland in Hampshire.