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Forest and

According to the Food and Agriculture Organization of the United Nations (FAO) a forest is an area with an area of at least 0.5 ha whose trees reach 5 m in height and cover more than 10% of its surface.  But this definition does not take into account all the other forms of life that populate it. A tree is never alone. If by its size and longevity it is the pillar of the forest, it is accompanied by a multitude of animals, plants and fungal species, whose interactions and roles are essential and form a singular ecosystem, the forest ecosystem. The proper functioning of this rich and complex ecosystem, based on biophysical processes of matter and energy transfer, is crucial to maintaining the many services that the forest provides us. In particular regulation services, that is to say the capacity to modulate phenomena such as climate, the occurrence and extent of floods, air or water quality in a direction favorable to society. . The benefits of a healthy forest are invaluable.

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Forests provide us with many services

They are a biodiversity reservoir of animal, plant and fungal.

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They are carbon sink and 

regulate the climate.

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They regulate water cycles and limit flooding and erosion.

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and secondary forests

Primary forests are made up of native species that have not been logged or cleared by humans and where ecological processes are not significantly disrupted. If there has been human activity in the past, a sufficiently long time has elapsed for the forest to have reverted to a primary state. Secondary forests are forests that have regenerated where primary forests have disappeared due to natural phenomena or human activities (agriculture or livestock breeding). These forests present major differences in terms of structure and/or species that compose them compared to primary forests. Secondary vegetation is generally unstable and represents successive stages.

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Polynesian Forests

Forests today cover 31% of the land surface of our planet, and we distinguish three main types depending on latitude and climate: the boreal forests of the Far North, the forests of temperate zones and the tropical forests located between the Tropics of Cancer and Capricorn. In French Polynesia, where the forests are tropical, no forest inventory has ever been carried out. As the surface areas of the different types of forests are only estimated, it is not possible to quantify the evolution of the environments. According to the Global Forest Resources Assessment (2015), the forested area covers 200,000 ha or 57% of the surface area of Polynesia, and natural forests (excluding plantations and coconut groves) are estimated at 140,500 ha, including 30,000 50,000 ha of primary forest with little or no disturbance by man. These primary forests have strongly declined in the low and medium altitude zones of most of the islands. Meyer (2006) estimates that 1/3 of the original forests have disappeared, and are today only present in the interior of the islands.  The distribution of forest and vegetation types (coastal vegetation, supra-littoral forest, semi-dry, mesophilic, hygrophilous and ombrophilous, summit scrub) between archipelagos is also very variable due to the ecological characteristics specific to each archipelago or island and of their agricultural and forestry potential.  The coastal, plain and valley forests have been modified since the arrival of the first Polynesians who carried with them several so-called “useful” plants, with multiple uses (food, construction, medicinal). Many other species were then introduced by Europeans who arrived in several successive waves since the 16th century. The plant formations of the Marquesas, Gambier and Austral Islands are particularly devastated by free-ranging animals. The Austral Islands are very affected with their natural forests reduced to shreds and do not exceed 1 to 5% of the surface area on the islands. In Rapa, only 17% of intact natural forest remains.  Dry and semi-dry forests occupy approximately 1,000 ha. Along with coastal forests on limestone plateaus, these are the rarest plant formations. Coastal forests only exist on isolated islets.

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Invasive exotic species (EEA)

For the advantages they provide, Man displaces many animals and plant species. The acceleration of trade has increased introductions and it is now estimated that more than 40,000 exotic species are spreading at an unprecedented rate on the planet. While not all are harmful, more than 3,500 are considered invasive alien species (IAS). Once introduced and acclimatized, they multiply without human help and then colonize their new territories, threatening ecosystems, natural habitats and local species. Rapid growth, absence of predators, strong reproduction, are all factors which explain the success of their invasion. These IAS often form dense covers (grassy mats, liana cover, thickets and so-called monospecific forests) which smother natural vegetation, eliminate native and endemic plants, impoverish and dry out the soil, thus promoting erosion and increasing the risk of fires. . The threat of invasive exotic species is particularly strong on island territories, particularly overseas. Due to geographic isolation, species evolved far from continents, which allowed the emergence of a high rate of endemism and consequently a high vulnerability to biological invasions. Invasive exotic species are among the main causes of the erosion of overseas biodiversity. In French Polynesia, the primary flora includes approximately 900 species of native plants, 550 of which are endemic. Since the arrival of humans and particularly in the 18th century, more than 1,800 species have been introduced, of which more than 600 have become naturalized and constitute the secondary flora. 10% of this introduced flora is today described as IAS (trees, shrubs, lianas, herbs, aquatic plants) and 35 species have been officially declared “species threatening biodiversity” due to their proven ecological impact. Their planting and multiplication are formally prohibited, as is their transport from island to island.  Once widely established, IAS are very difficult to manage and eradicate. This  requires significant human resources over long periods of time. Prevention of their introduction, their spread and the restoration of biodiversity are therefore decisive.  To know more :

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By definition, agroforestry covers all agricultural practices that combine trees with agricultural cultivation and/or livestock farming. The proper integration of trees makes it possible to increase production, diversify income and promote ecological services. To ensure the preservation and renewal of natural resources (water, soil fertility, biodiversity, etc.) According to Lundgren and Raintree (1982), the management of agroforestry systems is based on the search for the sustainability of diversified production by promoting the ecological, economic and social interactions existing between the components of these systems. Agroforestry constitutes one of the solutions for the sustainable use of limited natural resources and adaptation to global demographic, economic and climatic changes. By multiplying plant strata, agroforestry increases the diversity of species, habitats, ecological niches, ways of occupying space, functions and ecological functioning. The rates of use to environmental resources are also increased because these devices improve the capture, fixation, use and recycling in situ of these resources. In our project, 26 ha located at the bottom of the Mo’aroa valley are allocated to agroforestry. Food (spice), medicinal and dye species will be included. This agroforestry zone is also part of the educational space, open to the public.

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Mataiae, Mo’aroa Valley

AOA Polynesian Forests operates on an area of 250 ha within a large watershed of more than 1,500 hectares, framed to the west and east by high ridges; to the north, from the edge of the caldera; and to the south, from the edge of the Atimaono lagoon. Starting downstream, the valley is named Mo'aroa, as is the river which crosses it. Upstream, the valley splits into two. The main valley is then named Vaitunamea while the river is still called Mo'aroa and its tributary is called Mairipehe. Within this large watershed, the first plots of the AOA estate are accessible by a forest road following the river up to three-quarters of its length in a south-north direction. A few hiking trails traced by hunters then allow you to reach the caldera in the center of the island. Outside of these trails and when leaving the river beds and streams, access to humans quickly becomes complex due to the density of the vegetation and the slopes which become steep when approaching the ridges. The vegetation is mainly made up of invasive species (as is the case almost everywhere in French Polynesia). The rate of native species, however, increases slightly with altitude. Part of the AOA domain was named “Amélie domain” in the past. History has forgotten why this name Amélie... To discover the Mataiea legend

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