{"id":38956,"date":"2025-09-03T14:08:09","date_gmt":"2025-09-03T12:08:09","guid":{"rendered":"https:\/\/srfb.be\/?p=38956"},"modified":"2025-09-03T14:17:28","modified_gmt":"2025-09-03T12:17:28","slug":"comment-adapter-les-forets-aux-changements-climatiques","status":"publish","type":"post","link":"https:\/\/srfb.be\/en\/2025\/09\/03\/comment-adapter-les-forets-aux-changements-climatiques\/","title":{"rendered":"How can we adapt forests to climate change?"},"content":{"rendered":"

Climate change is having an impact on many tree species and on the very functioning of forest ecosystems. Foresters are wondering how best to adapt their forests to make them more resilient. This is no easy task, as there are no miracle recipes and the factors to be taken into account come from a variety of fields: plant physiology, soil protection, silvicultural strategy, introduction of new species and provenances, etc.<\/p>\n\n\n\n

This article sets out some basic points relating to these matters that foresters cannot ignore.<\/p>\n\n\n\n

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Summary<\/h3>\n\n\n\n

There is no magic formula for ensuring forest resilience. To achieve this objective, forest management must take multiple factors into account.<\/p>\n\n\n\n

Understanding the strategies used by tree species to adapt to drought is fundamental to making the right choice of tree species for a given site. What are avoidance strategies and tolerance strategies based on delaying desiccation? What are the advantages and limitations of these strategies? Which species are concerned?<\/p>\n\n\n\n

This article answers these questions about plant physiology, before going on to discuss other essential issues, including soil conservation, silvicultural techniques and the introduction of species and provenances.<\/p>\n<\/div>\n\n\n\n

1. Plant physiology*<\/sup><\/h2>\n\n\n\n

Preamble<\/h3>\n\n\n\n

Water (raw sap1<\/sup>) rises in the shaft thanks to a tension phenomenon, directly linked to the evaporative demand of the air. This demand
is satisfied by evapotranspiration2<\/sup> leaves. So, under the effect of heat (solar energy), the liquid water contained in the leaves passes from
into the ambient air in a gaseous state. This leads to a water deficit in the leaves, which puts the tree under stress and causes the sap to rise. By a \"domino effect\", the rise in sap causes tension in the roots, which compensate by absorbing water from the soil (raw sap). Evapotranspiration is therefore the driving force behind the circulation of water in the tree.<\/strong><\/p>\n\n\n\n

When there is a shortage of water in the soil and drought sets in, the tension becomes greater, especially when the evaporative demand from the air is high (dry air). This can lead to ruptures in the water columns of the vessels conducting ascending sap. This rupture phenomenon is known as cavitation<\/strong>. This causes air bubbles to form in the water column.gas embolism<\/strong>. This hinders or even makes it impossible for water to circulate.<\/p>\n\n\n\n

\"\"<\/figure>
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Photosynthesis<\/h4>\n\n\n\n
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  1. Chloroplasts trap light energy<\/li>\n\n\n\n
  2. Water penetrates the leaf<\/li>\n\n\n\n
  3. The CO2<\/sub> penetrates the leaf<\/li>\n\n\n\n
  4. The sugar leaves the leaf<\/li>\n<\/ol>\n\n\n\n

    A. Vessel
    B. Stoma<\/p>\n<\/div><\/div>\n\n\n\n

    \"\"<\/figure>
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    The sugars synthesised by plants are used for respiration, growth and defence (see point 4). Some of these sugars are stored in the form of starch, mainly in the crown and the main branches.<\/p>\n<\/div><\/div>\n\n\n\n

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    Note<\/h3>\n\n\n\n

    Root absorption is made possible by mycorrhizae3<\/sup>In this case, it is the fungi that pump the water from the soil before returning it to the roots. In return, the tree gives the fungi some of the sugars synthesised by photosynthesis.<\/p>\n\n\n\n

    Some of the water in the leaves is used for photosynthesis, a photochemical reaction that transforms water (raw sap) and atmospheric carbon dioxide (absorbed by the leaves) into glucose (sugar) and produces oxygen. This complex reaction takes place in the leaves and is only possible in the presence of chlorophyll. Its simplified formula is 6 CO2<\/sub> + 6 H2<\/sub>O <\/path><\/svg><\/span> C6<\/sub>H12<\/sub>O6<\/sub> + 6 O2<\/sub>.<\/p>\n\n\n\n

    The glucose produced is used by the plant for its metabolism4<\/sup> or stored in the form of starch (reserves).<\/p>\n<\/div>\n\n\n\n

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    1. Water and dissolved mineral salts present in the soil.<\/li>\n\n\n\n
    2. It is more correct to speak of evapotranspiration rather than transpiration, a term more suited to the animal world.<\/li>\n\n\n\n
    3. Symbiotic association between a fungus and the roots of a higher plant. This is known as mycorrhizal symbiosis (symbiosis is a mutually beneficial association between several organisms).<\/li>\n\n\n\n
    4. Metabolism is the set of chemical reactions that take place within each cell of a living being, enabling it to sustain life, reproduce, develop and respond to environmental stimuli. Source: Wikipedia<\/a><\/li>\n<\/ol>\n\n\n\n

      * Plant physiology is concerned with the functioning of plant organs and tissues and seeks to clarify the nature of the mechanisms by which the organs perform their functions and the plant develops in its environment. It includes the study of water relations and photosynthesis. Source : https:\/\/biologievegetale.be<\/a><\/p>\n<\/div>\n\n\n\n

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      1.1 Strategies of tree species to cope with drought<\/h3>\n\n\n\n

      Among forest species, there are three strategies for adapting to drought.<\/p>\n\n\n\n

      1.1.1. The avoidance strategy<\/h4>\n\n\n\n

      The avoidance strategy is based in particular on :<\/p>\n\n\n\n