Project design in Vitiforestry: Techniques enriched by stakeholder relationships. Four questions to Pierre Hermans, Director of the Research Department

As Director of Reforest'Action's Research Department, can you explain to us the extent to which the design of a vineyard forestry project is built in consultation with the stakeholders?

The implementation of wine-forestry projects is realized in consultation with the stakeholders, particularly with the vineyard's technical teams. Indeed, each project is unique and aims to provide real added value - in environmental terms, of course, but also in landscape and social words.

We are integrating a diversity of natural plant structures (hedges, isolated trees, shrubbery, windbreaks) within a highly codified system and on high-value land, where every square meter is counted.

The design of a vineyard project is based on the balance between viticulture that must remain productive and the return to a naturalness that positively impacts biodiversity, soil life, air purification, and water regulation ...

The first vocation of a vineyard remains the production of grapes. Our role consists in reconciling this objective with the indispensable responses we must provide to the challenges of our time - loss of biodiversity and global warming.

In this spirit, we maintain a permanent dialogue with the vineyard teams and accept mechanization not as a constraint but as a basic fact that we consider.

For example, there is no point in suggesting that we plant a tree six meters from the row if we know that a tractor needs seven meters to make a half-turn at that precise spot!

Champagne, Cognac, Bordeaux ... each region and vineyard has its specificities and practices, which we must adapt with humility. Nevertheless, the objective always remains to maximize ecosystem services to benefit the environment and the vineyard.

The project design aims to obtain a series of benefits. Can you present us with the contributions of the vitiforestry?

1/ At the plot level, we can distinguish three types of benefits:

1. Environmental benefits: the hedges and trees will provide habitats and food for many species (insects, reptiles, small mammals, birds) that had deserted the intensive monospecific vineyards. A whole natural balance is thus recreated. Moreover, it includes many predators, applicable against the pests of the vine.

2. Agronomic benefits: hedges and trees contribute to the improvement of soil quality, provide natural humus, promote water exchange, and fight against erosion and water runoff, for example.

3. Bioclimatic benefits: judiciously planted, the vitiforestry plantations have a significant effect on the stress of crops confronted with extreme variations in climate; they help to temper extremes, limit the impact of wind, reduce the effects of frost or summer heat waves.

Many ecosystem benefits are further enhanced at the farm level, mainly when the vineyard forestry system allows for the fragmentation of plots and the recreation of ecological continuity between them, or even for their reconnection with their natural environment (with a nearby forest, for example). The larger and more integrated the territory, the environmental value can be added. Moreover, from a particular scale, one can speak of the significant creation of carbon sinks, allowing to fight against global warming, but also of a natural landscape impact.

2/ At the farm level, four types of benefits can be distinguished:

1. Diversification of production: timber, energy wood, RCW, fruit.

2. The recreation of fertility and biodiversity in situ: the tree is a natural ally in restoring vineyard soils. The contribution of organic matter in the form of leaves and roots or even crushed wood is a significant asset in enriching the soil, not to mention that the deep root system of the tree decompacts the soil and reduces potential asphyxiation. As a result, soil life is stimulated, and the hummus is stabilized. In addition, the presence of trees in a plot substantially impacts the abundance of earthworms due to the presence of grass and the abundance of specific microbial taxa.

3. Natural pest control: Agroforestry provides botanical diversity and an additional layer of vegetation, creating new ecological niches. Trees allow for improved biological control through habitat conservation or enhancement.

4. A positive image of a winery or an appellation: trees reduce their environmental impact.

3/ On a territorial scale, the vitiforestry generates two main types of benefits:

1. Carbon storage: trees are natural carbon sinks. They not only mitigate the effects of climate change but also help to recapitalize the soil in carbon.

2. Biodiversity: all tree elements are excellent sources of habitat for a whole range of flora and fauna: a perfect way to restore ecological corridors and contribute to the objectives of the Green and Blue Framework.

What expertise do you bring to the table, for example, regarding the choice of species?

We provide various types of expertise. That of the choice of species is quite characteristic of our work.

The choice of species is naturally based on their adaptation to the site - particularly to the nature of the soil, which is often very typical in the wine region. So naturally, we will always look for the most remarkable possible diversity to maximize the resource for food and habitats for the fauna.

The growth potential and aptitude for pruning are also elements to be considered to limit the encumbrance and allow a good cohabitation with the vine.

Particular attention will also be paid to the potential undesirable effects, and it will not be a question of importing into vineyard pathology that could affect the vine. Thus, species likely to be affected by root rot, or rusts like vine rust, will be systematically proscribed.

Finally, even if it is not the primary criterion, the landscape coherence and the integration in the very Cartesian universe of the vine are studied. Often a dominant species is selected to build the aesthetic framework of the project. To this species, which can represent 40% of the total number of plants, we graft seven to ten complementary species on average, thus ensuring the necessary diversity.

Can you give us some examples of points to watch out for when building a wine-forestry project, and to what extent can you be flexible enough to deal with possible hazards?

We make sure to bring a solid project design while constantly adapting.

Planting trees in a vineyard is not without consequences. Therefore, it becomes essential to carefully study the design of the project to avoid competition with the vineyard and undesirable effects, such as:

- The problem of shading is the first element to consider. This shading will be directly related to the axis of orientation of the hedge. For example, a hedge-oriented North-South will have little impact, while an East-West structure will deprive up to six rows of vines of sunlight, which is not bearable. Beyond the planting, it is the height of the plants, and thus the future maintenance, that will have to be thought out. High hedges or wooded strips will be fine in some places, but regular pruning will be necessary, which is not without consequence on the workload of the vineyard teams.

- Water competition is another potential problem, the severity of which varies according to the distance between the hedge and the vines and according to the species chosen and its root characteristics. Nevertheless, pruning can provide solutions since a plant's water needs are directly proportional to its aerial development.

- There may be other problems related to the vineyard, such as competition for land in a limited area. It may also be a question of respecting specific regulations to remain within the constraints of the given appellation - the minimum density of vines per hectare, for example. In addition, the operational management of the vineyard must be considered, knowing that there is no negotiation possible concerning the machine that requires six meters to make a half-turn and not one centimeter less!

At Reforest'Action, we have a wide range of expertise, and we propose a form of project design that listens to the needs of the stakeholders. Vitiforestry techniques, and more generally agroforestry, are constantly tested in the field with humility by testing techniques and looking for approaches best adapted to the local context.