The Sombrun Forest Garden Project

When I wrote ‘Drought and heat – thoughts about the future …‘ last month, little did I realise how this situation would continue and become more critical throughout August, causing considerable upheaval at the heart of the Sombrun Forest Garden Project! I have often said in these pages that I am working hand in hand with Nature, that really it is Nature in control, and this has taught me a valuable lesson this month: in following Nature, we have to be prepared for surprises, and things may not turn out as we thought. This year’s drought has caused me stop, forcibly, and made me realise that I have to adapt.

The photos below are symbolic of the conditions: on the left, one afternoon’s harvest of blackberries, and on the right, partial die-back of a goat willow tree.

The drought conditions continued right up the end of the month, despite some showers between the 16th – 22nd, and a short storm on the 29th; these only produced 25mm of rain in all, the same as for July, and didn’t alter things very much. Temperatures were again in the high 30’s and exceeded 40° on a couple of days. Looking back over the last few months, although the drought and heat have been severe, the weather in general has been remarkably stable, with no high winds or extreme storm conditions, which, given what has been happening in other areas of France, I am grateful for. The full monthly weather record is given below.

Watering has been the main activity this month, and it has been a question of just helping the trees here to survive, by giving them some top water and trying to keep their mulches moist – almost impossible! But, apart from the soft fruit bushes (see last month’s Blog), where casualties have been high, the fruit trees and forest trees have been remarkably resilient, and I have lost only one tree, a red alder, and about half of the young paulownia hedge, to the drought. There have been a few wobbles here and there (again, see last month’s Blog), but those trees have held on.

I have also spent some time on grass-cutting (photo below) in both the Upper and Lower Gardens. This is a once-yearly event once the wild flowers have seeded and small mammal families have left the nest or burrow. It involves scything and strimming and raking up the grass into piles, which is then used as mulch in the swales and around trees. You can see from this photo just how dry it is, and in fact, in future, I may be constrained to do this even earlier because the long, dry grass presents a fire risk and I am surrounded by other houses – a danger I have to consider, obviously. There is a possible ‘window’ in early July, when the grass would not yet be tinder-dry, but the wild flowers would have finished in the majority. Not ideal, but it will in any case depend on the prevailing conditions each year.

Of course there’s a silver lining to the difficulties the Sombrun Forest Garden has been facing, and that is the squash crop! As the photos below show, I have got a good amount of various types (these are just two of five varieties), and so even if the cupboard will be bare of jams and chutneys and fruit leathers and compotes this year, at least a winter swimming in soup is assured!

My thoughts about the future have also continued this month, and if, as seems more than likely, we are going to get these conditions regularly, I need to find a way to help cope with not only a lack of water, but a lack of water retention as well. You might be surprised to hear that I am optimistic, given the challenges that are presented, but change is under way on many levels, and I do actually welcome it for a number of reasons.

First of all, I don’t have a cast-iron plan (a cause to be grateful for my continued dallying over design!). Secondly, my ideas on planting for this winter had not yet taken shape, and they will now change completely. And thirdly and most importantly, ideas about how to move forward are flooding in and I would like to share them with you.

I have known for many years of a system called Hügelkultur (literally mound bed or culture), developed centuries ago in Eastern Europe, the principle of which is burying logs, smaller woody biomass and herbaceous biomass; the earth removed for the biomass, plus a further layer of mulch, is then replaced to form a mound on the top. In decomposing, the biomass and the many underground organisms working with it provide nourishment for the soil, and the whole thing retains moisture like a sponge over many years, making it a prime site for plantation and growth in general. Although I was familiar with the concept, I have never used it myself. But now, I think this could be a good technique to try for my porous, poor soil and the conditions we’re going to be experiencing¹.

Indeed, if 1.5m beds were installed on quite a wide area along the contour lines of my sloping land, they would retain any rainfall evenly along their length. And it is quite possible that they could supersede, or incorporate, the present swale ditches, because they would probably do the job of the swales even better. If you refer to the Site Map (Blog, December 1st, 2021) you can see the contour lines traced by the two swale ditches. If these became Hügel beds, with other beds in the spaces above and below them, the whole emphasis of the Forest Garden would change, and new possibilities would open up. Trees can’t be planted on the beds themselves, because these gradually sink over time with the decomposition, but small shrubs, and both perennial and annual herbaceous plants can. Gaps could be left in the beds for tree planting, or they could simply be planted alongside, so that they would still benefit from the moisture and nutrients from the bed.

The photo below shows one example of a bed construction, ready for the earth to be mounded on the top. I already have a source of partially-rotted wood for free from close by in Sombrun, which would be ample for my needs. The main drawback to this idea is that I would need to have a mechanical digger on site to create the trenches for the biomass. This is not ideal, from a soil compaction point of view, but there would be too much to do by hand, and a mini-digger on caterpillar tracks would be sufficient and would keep any damage to a minimum.

Photo source: Wikipedia, in the public domain

Another idea I have had is to increase the ‘pioneer’ cover here. A naturally developing forest always starts with pioneer species, which are gradually displaced or die off as the true forest species take over. They pave the way, and this is called ‘forest succession’. The pioneers are useful because they grow quickly, colonise the land, increase the water retention and mineral content of the soil, provide habitat for increasing biodiversity, and are often nitrogen-fixing (in today’s gardening parlance, they are called ‘invasive species’!). Common examples of pioneer plants are acacia, blackthorn, goat willow and bramble, plus the two given in next paragraph.

As you can see from the grass-cutting photo above, the Forest Garden is still quite sparse, because of allowing sufficient space for the trees I have planted to develop. But as an interim strategy, if I were to fill in some of the spaces with fast-growing pioneers such as robinia (Robinia pseudoacacia) and autumn olive (Eleagnus umbellata), which are also nitrogen-fixing and drought-resistant, they would carry out the tasks outlined above, and could be coppiced, pollarded or simply removed as the ‘real’ trees (mostly fruit of various kinds in the centre Upper Garden) became more established. In the meantime, they would provide shade, moisture and biomass as well, allowing smaller shrubs and herbaceous plants to be established more quickly, and generally hastening the development of the Forest Garden as a whole.

I have already planted several robinia and autumn olive in other parts of the garden, but it hasn’t occurred to me until now to fill in other areas on a ‘temporary’ basis. I think this could be quite a useful strategy, in line with what occurs naturally, but over a shorter time span.

Another strategy which may seem obvious with hindsight is to choose more drought-resistant species. I’ve probably done fairly well so far with forest trees such as robinia, hawthorn and chestnut, and shrubs such as autumn olive, sea buckthorn and Siberian pea tree. But there are many more which would cope with drought and at the same time fulfil the criteria of cropping, utility and fertility for the Forest Garden. Examples of these are fig (fruit), acacia (coppice wood and nitrogen-fixing) and white mulberry (fruit, salad leaves and shade), some soft fruit such as barberry and goumi, and many medicinal plants and perennial vegetables such as Turkish rocket and sea kale.

On the media front this month, I came across this in the quarterly newsletter of EURAF, the European Agroforestry Federation. It is the joint statement released at the end of their conference held in Nuoro, Sardinia in May this year.

“We, participants in the 6th European Agroforestry Conference, believe, on the basis of the results of scientific research and the experience of many farmers, that the different forms of agroforestry are the best answer to produce commodities while preserving the soil, defending the climate, biodiversity and water resources, adding value to the beauty of rural landscapes and preserving our common European cultural heritage.”

The emphasis with EURAF is on larger-scale agroforestry systems where arable crops can still be farmed in the conventional way, but the sentiment expressed in the above statement is just as relevant to forest garden systems, which are agroforestry on a smaller scale. Importantly, it is also an indication of the growing understanding both in the farming community and in the wider world that industrial agricultural systems have had their day. These larger-scale systems are to my way of thinking a sort of half-way house to where we should be going, but nevertheless a step in the right direction. For further information on agroforestry systems see my Article no. 1, Agroforestry and the Forest Garden, May 31st, 2020.

¹ I am grateful to permaculture blogger Lis for reminding me of this. Her blog can be found here.