How to implement effective reforestation? What does an ecological restoration expert think?
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To continue our series of interviews on the subject of reforestation, we asked Elise Buisson, expert in ecological restoration. Researcher and Senior Lecturer (HDR) at Avignon University, she is also part of the Natural and Cultural Heritage Restoration Engineering team within The Mediterranean Institute of Biodiversity and Marine and Continental Ecology (IMBE). His research applies to the conservation management and ecological restoration of ecosystems degraded by intensive agricultural practices.
1. What are the main strategies and methods used in ecological restoration through reforestation?
The main strategies
They are the same as for all restoration projects, whether forest or other ecosystems. They depend mainly on the initial state of degradation, the means available and the regenerative capacity of the ecosystem in question. There are three strategies:
Rehabilitation/reassignment
It is a process of making severely degraded land suitable for cultivation or a condition suitable for another purpose (i.e. an ecosystem different from the pre-degradation ecosystem — often the case of gravel pits).
Rehabilitation
It consists of management actions aimed at restoring a level of ecosystem functionality on degraded sites. The objective is the renewed and continuous supply of ecosystem services, rather than the biodiversity and integrity of a designated indigenous reference ecosystem.
Ecological Restoration
It is a process that helps to restore an ecosystem that has been degraded, damaged or destroyed and that still concerns the preservation of biodiversity and ecological integrity. Other approaches to ecosystem restoration may focus only on providing ecosystem services (such as rehabilitation for example).
Did you know that? It must be clear that tree plantations for forestry or other landscape purposes are not restoration. Moreover, they should not be called forests because they do not function as forests. They are “simple” plantations. For example, the term Landes forest is not always appropriate. A small portion of the forest is actually a natural, mixed forest. A lot of it is actually just a plantation.
The various possible methods of forest restoration
The method chosen for the reconstruction of the forest (but which is also valid for other ecosystems) also depends on the capacity of the forest to regenerate, especially in its landscape context (fragmented or not).
Natural Regeneration
Here, the degradation is stopped. Nature is then left to do its thing, without human intervention: the germination or any other recruitment of biotic elements (plants, animals and microorganisms) results from colonization, dispersion or a natural process In situ.
Assisted regeneration
It is an approach that is based on triggering the natural regenerative capacity of living organisms remaining on or near the site to be restored. It differs from the active reintroduction of living organisms to a site and from natural regeneration. This approach is often applied to sites with low or medium degradation. Assisted regeneration interventions include the suppression of pest organisms, invasive exotic species, or species that are undesirable or competitive with seedlings of naturally developing woody species, the restoration of disturbance regimes, and the provision of resources to accelerate colonization (for example, the installation of artificial perches for birds dispersing seeds).
When natural regeneration is weak, in certain highly anthropized landscapes (with a high activity of overgrazing, continuous wood extraction, bush fires or very fragmented), or on highly degraded soils and under certain unfavorable climates, It is then necessary to be more proactive in the restoration process. This can involve improving the soil (adding compost for example), planting trees, etc.
2. How to assess the suitability of an area for a reforestation project?
The key principle of a reforestation project
By definition, a reforestation project can only take place where a forest was present before degradation.
∙ Reforestation or reforestation refers to the restoration of a forest on land that was previously wooded.
∙ Afforestation or afforestation refers to the establishment of a forest on land that was previously not wooded.
Moreover, one could ask the question of the difference between reforestation and reforestation.
Some people use them as a synonym: reforestation = reforestation.
Others say that reforestation includes reforestation and afforestation. I think that this second solution is more confusing.
As I was able to write in the article” For reasoned reforestation ” from the magazine “Pour la Science”, setting up a new ecosystem where it did not exist before poses many challenges. In the absence of a pre-existing forest, the choice of trees adapted to this environment becomes difficult, thus increasing the risks of failure to install them. A striking example of these difficulties is illustrated by the work of Shixiong Cao of Minzu University of China, in Beijing, in 2008. His research has shown that attempts to reforest natural grasslands and steppes in semi-arid or arid regions of northern China to counter desertification have met with resounding failures. Only 15% of the planted trees survived. The main reason for this is the lack of water. In addition, the very presence of trees has resulted in a decrease in soil moisture, thus leading to a reduction in plant cover. Bare ground is exposed to intense wind erosion..
How to assess the suitability of a reforestation project?
So a good indicator is to know What ecosystem existed before the degradation Did not take place. If It Were from the Forest, the 2E Indicator is The Level of Degradation. If the soil has been completely destroyed, planting trees does not make sense and it is therefore possible to opt for a reallocation (aiming at an ecosystem other than the forest). That said... it depends on the resources you put into it.
For example, following mining, if the soil has been preserved (stored), but not too long (it is better for it to maintain its properties), it can in this case be re-spread after exploitation to accommodate plantations. If the latter are diversified, if natural colonization is possible from the surroundings (i.e. there is some forest left in the landscape) then restoration can be relatively effective.
The Case of Fires
With regard to the level of degradation, it is interesting to mention that fire is a normal disturbance (we also say endogenous disturbance or environmental factor) for some ecosystems (and therefore not a degradation). In Mediterranean pine forests, scrub and scrubland, species are adapted to fire. Cork oak has thick bark to survive. Heathers, Arbutus Trees, Kermes Oaks have the ability to start from stumps. Aleppo pine has serotinous cones (which keep their seeds in the cone for several years, long after the seeds mature, and release them after exposure to fire). Rock roses, rosemary, etc. germinate after the fire has passed. So, in this type of ecosystem, after a fire has passed, the best thing is to do nothing and let nature regenerate itself, since it is adapted.
3. Is the massive planting of trees an adequate response to the challenge of climate change?
All natural/semi-natural ecosystems in good working condition store carbon.
We focus on trees because carbon is visible (the trunks are visible), while the carbon stored in Peatland Soils, for example, is not visible to the general public (same for meadows, Posidonia meadows, etc.). It is therefore primarily a matter of perception, of ignorance.
I also think it's because it's easy at first glance. Anyone can plant a tree. Restoring a peatland that has been drained and cultivated... or replanting posidonia... it's much less so (and then... how many know what a peatland or a posidonia is?).
All natural/semi-natural ecosystems are necessary to maintain biodiversity and various ecosystem services.
Tree planting thus sheds light on the forest (and again... not always, because many will confuse forest and plantation). It does not affect other ecosystems that are just as important for carbon storage, and that have their own biodiversity and provide very specific ecosystem services. Mass plantations would result in a homogenization of landscapes and therefore a massive loss of biodiversity and ecosystem services other than carbon storage (for example, grasslands provide food for livestock).
While tree planting can be beneficial in deforested areas, it can be grown in naturally herbaceous ecosystems, such as savannas or lawns. This practice destroys the habitats of numerous plant and animal species, thus affecting biodiversity and ecosystem services crucial to humanity. These ecosystems provide grazing areas and contribute to the recharge of groundwater, thus underlining the importance of maintaining them.
Moreover, not all forests are equivalent in terms of the fight against climate change.. Coniferous forests in boreal regions and high mountains absorb more sunlight and emit more heat than areas without trees. As a result, they are exacerbating global warming rather than reducing it.
The concern for “industrial” tree plantations
Use of mechanized machines that run on gasoline, disturbance of the soil and therefore emissions of CO2 stored there, use of wooden supports (which required deforestation) to maintain trees, etc. LTree Planting, If Done Industrially, Can Worsen Climate Change by being the source of greenhouse gases. She Can Also Cause Other Ecological Problems. When we talk about massive plantations, we often use exotic species or a small number of native species that are not enough to create a forest. They produce a plantation with little, if any, benefit for biodiversity or the environment.
The importance of restoring forest ecosystems in the long term
Moreover, planting trees to combat climate change is only useful if it is done as part of the long-term restoration of forest ecosystems. The planting of trees for exploitation causes the destruction of stored carbon (since the trees are taken and used at a given time).
Natural and restored forests absorb atmospheric CO2, storing some of that carbon in trees and soil. This storage is stable and can last for hundreds of years. On the other hand, plantations intended for production favor fast-growing and commercially profitable species, allowing rapid, but ephemeral carbon storage. Wood is often turned into paper pulp and then burned, releasing stored carbon into the atmosphere. Only its use in construction guarantees sustainable carbon storage.
Finally, focusing on the planting of trees, there is a risk of Reduce the ability of human populations to adapt to climate change while diverting attention from efforts to maintain intact ecosystems, to reduce the consumption of fossil fuels and/or to the search for more effective solutions.
Tree planting is apparently unproblematic in urban areas.
4. Can you share examples of notable success stories of reforestation as a tool for ecological restoration?
The Atlantic forest of Rio de Janeiro in Brazil
During the 16th and 17th centuries, this area was continuously destroyed by the exploitation of wood and its replacement by farms growing sugar cane and coffee, or by pastures for livestock. In the first half of the 19th century, as the city was experiencing serious water shortages, the emperor of Brazil Pedro II asked Major Manuel Gomes Archer to carry out a forest regeneration project, so that it could facilitate the formation of sources by penetrating rainwater into the soil. Thus, between 1862 and 1874, 72,000 seedlings were installed in an area that is now part of the Tijuca National Park. This project, which is now 160 years old, was a pioneer, as it used a large number of different species, mostly native, and planted heterogeneously.
In Fennoscandia
Intensive forest management has simplified the forest landscape there, threatening biodiversity. To save the latter, it is therefore necessary to restore the structural complexity of Boreal Forests Hitherto managed. The knowledge generated by case studies on ecological restoration suggests that prescribed burning positively affects many organisms at the beginning of succession. Creating gaps benefits some insects and fungi, but has a limited effect on birds, bryophytes, and vascular plants. The regeneration of deciduous forests seems to benefit species associated with light and deciduous trees, such as insects and some forest birds.
5. What are the specific challenges encountered when restoring ecosystems through reforestation, and how can they be effectively overcome?
The basics of effective reforestation
It is necessary to:
- Plant the right species in the right place by maximizing heterogeneity. This oObjective is quite easy to achieve if you involve the right people early in the project.
- That the project is well integrated into the socio-economic and cultural landscape and that it takes into account the needs of local populations. This objective is More difficult to reach in some regions of the world where communities are highly dependent on local natural resources. For example, if the population cooks over a wood fire and trees are rare, the ecological restoration of a forest patch is unlikely to be viable in the long term, because the wood will be experienced too frequently. In this case, it is then necessary to provide a plantation that can be used by the population for their current needs in addition to the reconstruction of the forest.
The Case of Europe
In Europe, it is Quite easy to reforest properly if you take the trouble (see the example of Fennoscandia above). That said, forest cover is naturally increasing in many areas in Europe due to agricultural abandonment. And as discussed above, post-fire restoration is not necessary (and may even be counterproductive) for fire-adapted forests. Reforestation in Europe will therefore mainly concern exploited forests that must be diversified for the benefit of biodiversity, but also to limit wasting (due to severe, drought, parasites, etc.)
It is crucial to promote varied plantings rather than monospecific ones, by combining different species with varied life traits. For example, in temperate regions, deciduous and evergreen trees, softwoods and deciduous trees, or species with different root systems should be mixed. The planting should be spread over several years to encourage a complex structure. It is also essential to limit the use of exotic species in favor of local species or, possibly, species from geographically close regions. This ensures better adaptation to climate change without compromising the balance of local ecosystems.
6. Why are native species important in reforestation initiatives?
As in any restoration project (that is, regardless of the ecosystem), the use of native species is essential. Indeed, they are those who have evolved in this particular environment and who will be able to forge rapid and effective links with other species present locally or who will recolonize the site. Trophic webs will be able to regenerate more easily and the ecosystem will become functional and resilient: for example, species that degrade leaf litter and thus ensure the cycle of nutrients in the restored ecosystem, or those that consume fruits, disperse seeds and therefore allow plant dynamics, etc.
Conversely, the use of exotic species can cause environmental problems. For example, when the first forestry institute was created in the Philippines in 1910, a reforestation plan was developed, including the planting of native and exotic species such as mahogany. However, the latter, by producing seeds annually unlike native species, rapidly colonized natural areas, thus posing environmental problems. Likewise, in the Pyrenees beginning in the 1960s, during a reforestation program, beech forests were replaced by spruces, modifying the composition of soil humus affecting and biodiversity, as evidenced by the decrease in springtail populations (studied by Thierry Gauquelin in 2004).
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7. What are the key criteria for evaluating the long-term success of a reforestation project as part of ecological restoration?
The most used criteria are (study https://doi.org/10.1111/rec.12586 ):
∙ The composition of the vegetation, that is to say the identity of the species, the number of species, the fact that they are native or exotic, the equitability index (frequency of the different species), the survival of the trees planted.
∙ The structure of vegetation, that is to say the coverage of the different forms of life (herbaceous, seedlings, seedlings, shrubs, trees), the height of the trees, the diameter at chest height, the coverage of the canopy. You can also measure the number of dead trees standing and on the ground and the quality of the litter (but this is less common).
∙ The Composition of Wildlife, that is, the number of animal species (often studied by group [birds, reptiles, etc.]) and the abundance of certain animals.
∙ The functioning of the ecosystem which involves studying physical and chemical parameters of the soil or the presence of bio-indicators (for example the bio-indicator of healthy soils, and less frequently the bio-indicator of pollination or seed dispersal).
8. What synergies can be developed between reforestation initiatives and other conservation projects to maximize overall ecological benefits?
I think that in fact, there must be good communication between entities working in conservation and restoration on the same territory. If money needs to be spent on catering in a given territory, it is important to ask yourself the following questions:
- Are the conservation areas in good condition? Do they require restoration actions? Is that the priority?
- If conservation areas are in good condition, should restoration be aimed at increasing connectivity between existing areas or not?
9. How to ensure the long-term commitment and support of local communities in reforestation initiatives?
The most important thing is to bring local actors together as early as possible. of the project, to listen to the different opinions and to involve them in decisions at each stage. It is necessary to be involved in the scheduling, at the implementing And at tracking the success of the project over the long term. While participation in planning and implementation is important for ownership, I think that involvement in monitoring success is what will make it possible to maintain interest in the project and its protection over the long term.
There are entire textbooks that can help you learn more about this subject:
∙ MEOR, Methodology for Assessing Opportunities for Restoring Forest Landscapes: https://portals.iucn.org/library/node/45771
∙ Collaborative monitoring: https://www.cifor.org/knowledge/publication/7159
∙ Mapping social landscapes: a guide to identify the networks, priorities and values of restoration actors: https://www.wri.org/research/mapping-social-landscapes-guide-identifying-networks-priorities-and-values-restoration
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