Practicing vitiforestry

Technical articles

Agroforestry Agroforestry in viticulture Fertility management in viticulture Climate resilience Biodiversity Energy production Pruning and training of the vine Pollarding Soil regeneration NBSOIL

Photo Credit: AlternatiVity

Vitiforestry refers to agroforestry applied to viticulture. This practice has benefits from a perspective:

• societal (minimal impact on natural resources)
• environmental (maintenance of biodiversity)
• economic.

It thus allows achieving a triple performance of the system.

What is vitiforestry?

Agroforestry is the association of trees and crops on the same agricultural plot, at the edge or in the middle of the field. Inspired by the management of bush vines, already practiced in Antiquity, the modern practice of vitiforestry adapts to mechanized viticultural systems. In viticulture, this practice presents innovative characteristics that respond to the principles of agroecology. Vitiforestry is an interesting solution for adapting viticultural systems to climate change.

According to Alain Canet, the principle of vitiforestry is based on three pillars:

• trees
• soil carbon management
• gentle pruning

Currently, there are different types of agroforestry arrangements:

• rows of trees interspersed between rows of vines
• shrub hedges at the edge of the plot or interspersed between vine blocks
• isolated trees planted within the vine row

The variety of arrangements and combinations of levers used in vitiforestry allows adaptation to many systems and meets various objectives of the operator.

Implementation of the technique

What criteria to consider?

Introducing trees into a vineyard plot requires taking into account various factors involved in the cropping system:

• The grape variety associated with its rootstock
• The training system
• The type of soil and environment (light, temperature, rainfall)
• The soil cover

These factors are chosen to ensure early ripening and sufficient maturity of the grapes and must allow moderate and efficient water and nitrogen supply to the vine, which will optimize grape ripening conditions.

The advantages or disadvantages in implementing a vineyard in agroforestry also depend on:

• production objectives,
• desired wine style,
• its valorization,
• the rules in the specifications in appellation vineyards,
• the risk of loss of production area if replaced by trees, in high value vineyards.

Which tree species to choose?

The choice of species must follow several rules:

• Choose hardy tree species adapted to local pedoclimatic conditions.
• Favor a diversity of species allowing to shelter a more varied auxiliary fauna. These auxiliaries (mites, spiders, bugs, ladybugs, Anagrus atomus) are then used as agents of biological control against vine pests (notably green leafhopper and grape berry moth). For example, hazel, hornbeam, field elm and common ash favor the development of the wasp Anagrus atomus, predator of the leafhopper green. Similarly, the common almond is one of the main hosts of predators of grape berry moth.
• Take into account the grower's valorization objectives (timber, firewood, fruits, ...)
• Choose tree species adapted to the vineyard terroir and if possible with light and non-competitive foliage for light.
• Consider the heterogeneity of the plot (moisture, depth...).
• Favor late species (alders, walnuts, ashes) so that the tree's demand and the vine's demand are not in competition.

Plant material must be of first choice and certified both sanitary and genetically. Moreover, it is preferable to work with young plants (1 year, 30/60 cm), bare-rooted, which have better establishment than older plants.

What arrangements?

When designing a viticultural agroforestry project, various parameters are considered. Regarding the type of tree formations (hedges, isolated trees, alignment, grove), several choices are possible depending on production constraints and the grower's expectations:

• alone
• combined
• at the edge of the plot
• interspersed between vine rows.

Here are some examples of arrangements to favor according to farm constraints:

• if the priority is to limit the effect of lateral winds, it is more appropriate to install a hedge at the plot edge.
• if the agroforestry practice aims to create resources and habitats for biodiversity and auxiliary fauna, it is preferable to favor a diversity of plant species and tree forms (bushes, hedge, trees) connected to each other.
• if the grower wishes to plant trees within the vineyard itself, isolated trees, aligned or a regularly pruned low hedge are the most suitable forms.

On already established vineyard plots, arrangement choices are constrained by the existing management (vine row orientation, spacing). In this case, several practices are possible:

• removing a vine row to plant trees
• planting trees more randomly replacing missing vine stocks

For a plot under creation or restructuring, tree arrangement choices are much freer.

For more information on possible arrangements and their functions, see this article.

Recommendations for tree management

As much as possible, it is recommended to :

• Favor North-South orientations to limit and balance tree shading on the vine.
• Provide a minimum distance of 3 meters between the tree line and the first vine row, ideally 4 meters.
• Aim for a distance of 25 to 30 m between each tree line.
• Tree spacing along the line will depend on the desired density.
• Maintain a low tree density: 30-50 stems/ha.
• Respect turning spaces at row ends for machinery operations.

Managing competition

For an agricultural plot to be considered agroforestry, it must contain fewer than 100 trees per hectare. In viticulture, it is advised to limit to a low density of 30 to 40 trees per hectare. In this configuration, no competition is observed during the first 10 years of co-planting (Vitiforest project).

There are various levers to manage competition between trees and vines.

By tree management

To limit shading but also root development, several techniques exist:

• reducing the aerial system in winter (and consequently reducing the root network) by pollarding the tree every 5 to 10 years (pollarding),
• pruning the canopy green to limit transpiration and thus water evaporation,
• root girdling by passing a toothed tool every 3 years to limit root development towards the vine.

By adapting vineyard soil maintenance

• The percentage of grass cover in the plot must be adjusted according to production objectives (grass cover in all inter-rows, every other inter-row…).
• Using temporary covers such as "green manure" can also be a solution to limit nitrate leaching while enriching the soil in organic matter. A cover based on legumes has the advantage of fixing atmospheric nitrogen, further enriching the soil.

By classical viticultural techniques

• Targeted fertilization techniques can be implemented to compensate for competition, especially for vine rows close to tree lines. Actions can be localized on the soil on a worked row or foliar at different stages of the vine cycle.
• Hydric competition phenomena can be compensated by techniques such as irrigation or fertigation.

Regulations

From a regulatory point of view:

• trees can be present within a vineyard plot or integrated, unless the specifications of an appellation (AOC, IGP) prohibit it.
• there is no national regulation concerning registration and declarations of agroforestry agricultural plots in the Computerized Vineyard Register.
• 10-are vine blocks must be maintained between each tree alignment.
• planting aids are based on actual vineyard surface, without considering areas occupied by trees.

Advantages

At the plot scale

Moderate climatic extremes

• Trees act as true air conditioners at the plot scale by their mechanical effect as barrier, partition, and edge.

• Their windbreak effect limits climatic stresses on crops.
• Their "parasol" effect is particularly relevant in the context of climate change. Indeed, decreased summer rainfall and higher temperatures often lead to early grape maturity and higher alcohol content. Thus, the presence of trees helps maintain or delay the harvest period.

• They create a microclimate benefiting the vine with higher humidity and creating a thermal buffer of 3 to 5°C.
• Vine evapotranspiration is reduced, root systems are less overheated.
• In the case of red wine, the tree's action would reduce alcohol content.

Improve water resource

• Agroforestry trees develop a deep root system, due to the presence of crops. They can bring water up from deep soil layers to the surface for crops.
• Water is also better retained in the plot thanks to soil structuring by roots (especially when trees are associated with cover crops).
• Finally, the deep root network of trees filters pollution, thus limiting elements reaching groundwater.

At the farm scale

Diversify production

• Timber: in agroforestry, valuable hardwoods (walnuts, wild cherries, whitebeams, service trees…) are used to produce quality timber. Harvests occur after several decades.
• Energy wood and Ramial Chipped Wood (RCW): hedges, pollarded trees, or suitable species such as poplar can be pruned more regularly to provide energy wood or RCW.
• Fruits: associating fruit trees and vines is often sought by growers to diversify production but also to give an image to the terroir.

Restore fertility and biodiversity in situ

Trees are real allies in restoring vineyard soils. The input of organic matter in the form of leaves and roots or chipped wood is a major asset in enriching the soil, not to mention that the deep root system of the tree loosens the soil and reduces potential asphyxia: soil life is stimulated and humus stabilizes. The presence of trees in a plot strongly impacts earthworm abundance due to grass cover, and the abundance of certain microbial taxa.

Naturally fight pests

Agroforestry brings botanical diversity and an additional vegetation layer creating new ecological niches. Trees improve biological control by conserving or improving habitat.

Contribute to the estate's image

Agroforestry also helps strengthen a positive image of a vineyard estate or appellation. In a context where viticultural practices are often criticized, trees help reduce their environmental impact.

At the territory scale

Store carbon

Trees are real carbon sinks. They not only help mitigate climate change effects but also contribute to recapitalizing soils in carbon. Agroforestry is recognized for its carbon sequestration capacity by the Kyoto protocol (articles 3.3 and 3.4). With a density of 50 trees/ha managed in agroforestry, it is estimated that 40 tons of carbon per hectare could be trapped.

Restore ecological networks

All tree elements are excellent habitat sources for a whole range of flora and fauna. A very good way to restore ecological corridors and contribute to the objectives of the Green and Blue Network.

How much does it cost?

The unit and total price of an intra-plot tree planted and protected is €18 excluding VAT and breaks down as follows:

• supplies (plants, mulching, deer protection, stakes) amounting to €7.30
• work (soil preparation, laying mulch, protections, and planting) amounting to €5.20
• project engineering and monitoring over 3 years amounting to €3.50.

Prices increase for fruit species.

In terms of labor time, for 50 trees per hectare, count:

• half a day for preparation
• one day with 3 or 4 people for planting (with mulching, protections, etc.)

Pruning the trees will require a few hours per year in the first years then half a day per year per hectare for pruning already formed trees.

Appendices and links

Est complémentaire des leviers

• Practicing agroforestry
• Implementing agroforestry arrangements
• Practicing gentle vine pruning
• Pollarding pruning
• Practicing total grassing in vineyards
• Planting hedges
• Inter-row grassing in vineyards

S'applique aux cultures suivantes

• Vine

Défavorise les bioagresseurs suivants

• Green leafhopper