Efforts to increase tree planting are admirable, but as climatic conditions intensify, where is the post-planting care?
AS the sun blazes down from the summer sky and temperatures soar to what appear to be new heights, spare a thought for the record number of young trees planted during the autumn, winter and spring. Government initiatives – both central and local – have increased the numbers of trees being planted and the focus is on getting ‘more in the ground’. Add to this the ever-increasing and worthy efforts of community groups across the country and the demand for trees has, in my experience, never been higher.
Leaving aside the questionable methodology of planting by numbers and the lack of any clear national strategy for tree planting with questions such as realistic canopy cover targets, tree population diversity and resilience or a clear vision as to what is to be achieved largely unanswered (or confused in a plethora of partial and incomplete information), there is a more pressing series of questions to be answered.
Imagine visiting the garden centre and spending large amounts of money on sensitive garden plants, then taking those plants home, planting them and, after an initial watering, forgetting them with the assumption they will be okay. Yet this is what is happening with many of the young trees being planted today. There are exceptions of course, and many tree-planting groups and local authorities have maintenance programmes in place. However, many of these are restricted to watering alone, with other aspects of horticultural best practice ignored, forgotten, or just not understood.
Post-planting formative pruning, removal of other vegetative competition, the vagaries of different species, the detrimental effects of compaction, nutrition, support removal and adjustment and many other horticultural principles seem to be ignored when it comes to young trees. At least this is my observation when looking at various tree-planting schemes over the years. The one simple ingredient which seems to be missing is care.
Going back to our garden centre plants for comparison, would uncontrolled weed growth be allowed? Would mowers be allowed to cut so close to the plants that physical damage occurs? Would a rock-like soil surface be allowed to develop? Would obvious formative and cultural pruning be ignored? Would nutritional needs be ignored? Would watering once a fortnight irrespective of weather conditions be the norm? Would a begonia be treated the same as a hydrangea or a hebe or a tomato? The answer is obviously no.
Horticultural skills and knowledge, coupled with a great deal of care and thought, would be applied. But this does not appear to be the situation when it comes to young trees.
Perhaps it is the perception that the young tree (and I am thinking of standard trees, those which are commonly planted on roads, in parks, public gardens and feature in many of the new developments springing up across the country) emerging from the nursery is the finished product, ready to plant and fulfil its genetic potential without further horticultural/arboricultural intervention other than the periodic and often infrequent watering.
Yet the reality is that the young tree from the nursery is in the early stages of its development. A 12–14 cm girth tree may be seven-to-ten years old, dependent on species at the time it leaves the nursery and is planted in the landscape. Many of these trees have the genetic potential to live for 2–300 years or more, with even the shortest-lived species surviving for 50 or 60 years. So, the young tree may be a fifth of the way through its expected life at planting – or, in the case of long-lived species, just a 30th or less. In each case and all the variables in between, they are just juveniles removed from a nursery environment where they have been cared for, watered regularly, provided with nutrition, pruned as necessary, grown in conditions which optimise growth with attention paid to the individual requirements of a particular species and, dare I say it, cared for by professionals who, on the whole, love trees.
The general maintenance elements mentioned above are well known, yet so often overlooked. Soil compaction at the surface can be easily rectified using a border fork at watering. A simple mulch will suppress weed and other vegetative competition and keep mowers away from the base of the tree. Regular inspection will ensure stakes and ties are removed when appropriate. A simple moisture test (using a probe costing about £10) will allow for watering to be applied when required or the use of irrigation bags can deliver a known quantity of water in a known period of time.
Whether these simple things are done is another question, but the recipe is straightforward.
However, there are other factors which are less simple and obvious and require a degree of horticultural knowledge and recognition that not all tree species develop in the same way or have the same developmental requirements. It sounds obvious, but much young tree maintenance, where it occurs, is delivered according to a generalised recipe and applied to all, irrespective of species.
To offer some examples, it is known that the Turkish hazel (Corylus colurna) may require irrigation for a longer period – three or four seasons – post-planting to establish fully, while other species will develop the capacity to establish with reduced irrigation after one season.
When considering formative pruning, different species require different regimes to develop into healthy mature specimens. For example, the Japanese pagoda tree (Styphnolobium japonicum) has to develop its crown slowly, so regular pruning is necessary in its formative years, both on the nursery and subsequently after planting.
Failure to do this allows the branches to grow rapidly, resulting in a thin, spindly crown which often suffers significant dieback at the tips. It is, perhaps, the reason why the tree has such an unfortunate reputation and is not used more widely in the UK.
Other species which benefit from this type of pruning and controlled rather than rampant crown development include Gleditsia triacanthos, Robinia pseudoacacia, Celtis occidentalis and perhaps the much-maligned Fraxinus oxycarpa Raywood. Other species, such as Liquidambar styraciflua, have strong and dominant leaders and require little pruning post-planting.
There is not enough space in this column to explore these and other challenges fully, but trees from the nursery are not the finished product. They need nurturing after planting.
They need care and attention if they are to deliver their full genetic potential and perhaps there needs to be a reinforcement of sound horticultural principles which, it could be argued, mainstream arboriculture has lost
sight of.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here