WHY IS THERE A TREE IN THE MIDDLE OF THAT VINEYARD?
by Andrew Chalk
In the case of Château Anthonic in the Bordeaux AOP of Moulis-en-Médoc it is the practice of agroforestry, an increasingly popular agricultural technique in Bordeaux. Agroforestry involves the planting, or leaving planted, trees directly amid the rows of vines. Jean-Baptiste Cordonnier, co-owner and agronomist at Château Anthionic explains “Our vineyards are part of a complex ecosystem to which we try to give back all its biodiversity: rural hedges, vegetative cover, preserved wetlands, forest plots…For a few years now, the trees have been progressively making their return within the vineyard plots”.
THE PRACTICE OF AGROFORESTRY
He and son Théophile replace two rows of vines with a row of trees after each twenty rows of vines, a 9% vine loss. With the maximum distance kept to 15m the vines and trees are close enough to share through fungi. They can also add, between the rows of trees, smaller trees within the vine rows, and pruned like them. Both choices are pragmatic in that they can still use the same machines in the vineyard. They compensate for the loss of vines with replanting vines closer together. Only 0.9m versus 1m, an 11% gain that offsets the original loss. They also adjust their pruning regimen to have the same number of buds per hectare as before.
As well as the more diverse ecosystem, Jean-Baptiste considers trees a defense against water loss in hot years. He hopes to effectively reintroduce more moderate temperature harvests.
Anthonic made the first agroforestry steps ten years ago with the planting of the first hedge and continues the practice today.
Claire Villars Lurton of Château Haut Bages Liberal considers that a responsibility comes from position. “...as a classified growth Château Haut Bages Liberal has to be an example in what [the] viticulture has to be in the [near] future”. Their agroforestry involves planting about 3% of each hectare with trees, or about one row every 14 metres. She believes this leads to the following mutual benefits for trees and vines:
Soil fertility through a larger mycorrhizal network and nutrient capture (minerals, nitrogen) in a larger area than the vine. Mycorrhizal fungi feed on the sap of trees and vines and in return give them all the trace and mineral elements that plants need;
Limitation of erosion, soil stability: enrichment in humus by leaf decomposition ensures a more stable soil;
Natural protection of the vineyard: windbreak (reduces the water stress of the plants), moisture retention and therefore limitation of the water needs of the vines. Natural fight against diseases”.
At Château Guiraud Clémence Planty describes a more subtle approach that the winery has pursued since 1996. They do not remove producing vines, but plant herbs and hedges. They add trees where they can based on vineyard location and topography. “Agroforestry is our future, to maintain the equilibrium of our nature.” says Mme Planty.
Not all trees are created equal so far as this task is concerned. Benjamin Sichel of Château Angludet goes with ⅔ local varieties of fruit trees (peach, plum, pear, apple, quince, medlar, arbutus, cherry) and the remainder hardwood (cork oak, holm oak, maple).
Guiraud’s Clémence Planty explains their criteria “Linden trees and fruit trees are from the Rosaceae family and have the same mycorrhizals as the vine. This symbiosis increases the root prospecting of the vines and therefore the absorption volume of soil elements (soil, minerals, etc.)”
Claire Villars Lurton expresses similar sentiments “Yes we choose trees in function to their ‘mycorhizes’ affinity, trees and vines must have the same mycorrhizal network as fruit trees: peach, cherry .... Nut trees: birch, walnut trees ; noble woods : Siberian elm, hornbeam, country maple …any species except those from the forest, in particular fruit and nut trees. But above all, species that are symbiotic with the vine”
The preference for maple is expressed by Jean-Baptiste Cordonnier as well. “A mix is also important: it will provide more biodiversity, more species of fungi in the network and at the top end build a more resilient ecosystem.
In my mix I always have a significant percentage of maple trees that are natural companions of the vine, so they are supposed to cooperate with the same species of fungi and they share more genetics with the vine than other species.”
Just as important is what he steers away from “I avoid species that will be competitive for water like pines.”.
ADVICE FOR A NEWCOMER TO AGROFORESTRY
What advice would these experienced practitioners of agroforestry give to a winemaker considering introducing it?
Jean-Baptiste Cordonnier gives a cookbook hands-on approach “1. cover the soil 2. plant hedges 3. then introduce the trees inside the parcels. In that order. Trees first could be a mistake. They could suffer, compete, be ill, become support for parasites…” but adds a twinkle of polemic “give arguments to persons that still say that trees are problems in a field.”
Claire Villars Lurton is also loaded with practical advice “I will say firstly , bring back living soil by cover crop, by planting hedges ….trees.
Tillage, herbicides spray and mineral fertilization killed the soil, , fortunately it is reversible but we must act as quickly as possible, here is the major reasons for that:
Through plant covers, our objective is to have a LIVING SOIL. In order to :
▪ Increase the soil bearing capacity and thus avoid erosion.
▪ The aeration of the soil through the roots. That allows a better penetration of the water in the groundwater (the plant cover then acts as a sponge) and avoids the compaction of the soil (compaction causes the water to run off towards the rivers)
▪ Creation by the roots of organic matter in order to feed the soil life as microbial (mycorhizes...) and earthworms.
▪ Carbon sequestration from the atmosphere by storing it in the soil and transforming it into organic matter.
▪ Protection from drought.
▪ Natural fight against mildew and other diseases thanks to an important biodiversity and makes vines live longer through a natural fight against wood diseases (Esca, Etypiose...)
▪ Carbon sequestration from the atmosphere by photosynthesis of plant cover. Carbon is thus stored in plant organic matter. Their degradation by micro- organisms releases food that can be assimilated by plants (nitrogen, phosphorus, sulfur, potassium). Carbon is essential for photosynthesis. (if all agricultural soils had plant covers, we would capture 10 times more carbon than what we reject).”
Clémence Planty expresses the need for patience. “Take the time, the terroir cannot regain its ecological balance in a short time. For a good conversion, Guiraud took 30 years, to finally have wines classified among the best wines in the world like 2011, 2009, 2005, 2001, etc …”
Her contrary advice,regarding what not to do in adopting agroforestry, is to not to try to do things too fast! For Claire Villars Lurton at Haut Bages Liberal the message is that this is a journey not a project “All these changes have to be done step by step, as we damaged considerably our soils since 100 years, we need time to learn new methods in the function of each vineyard.
For vines at 10 000 plants per hectare, the introduction of cover crop and trees is very challenging, we need to invent new tools…., the most important is to share the experience of each other.
Today the ‘ agroforestry topic’ is a concern more and more widespread that I seek to convey with my colleagues in this way of thinking.”
AGROFORESTRY IN PERSPECTIVE
All of the proponents of agroforestry I spoke with saw it as part of a broader set of solutions to healthier vines in the future. They acknowledge that there may be issues, for example additional foliage providing cover for pests that vector disease such as Pierce’s disease, that still have to be answered. Ultimately, it will be, and it should be, whether agroforestry works which determines how much and how widely it is used. The proponents in Bordeaux are pathfinders in that quest.