Contenido
El manejo de los bosques naturales puede tener varios objetivos:.
Por ejemplo en Misiones, Argentina, casi dos tercios de su superficie está cubierta con bosques. Se explota el bosque nativo para diferentes usos. Las especies más valoradas son el cedro, el peteribi (para muebles) y el guatambu (para madera terciada). Hay extensas áreas de bosques implantados con pino (especie no nativa) y araucarias (especie nativa), principalmente en las márgenes del río Paraná. La producción forestal se destina a las fábricas de pastas celulósicas de Puerto Esperanza "Puerto Esperanza (Misiones)"), Puerto Piray y Puerto Mineral, a los aserraderos y otras industrias forestales existentes en la provincia.
Principales amenazas ambientales para los bosques.
El cambio climático, la contaminación o las plagas, entre otros, son algunos de los factores que afectan a los bosques.[7] En muchos casos, el interés de las compañías nómadas multinacionales por los recursos minerales, la construcción de presas que inundan amplias zonas selváticas o el crecimiento de las ciudades y las vías de comunicación (carreteras, canales, etcétera) son otras tantas razones para la regresión o fragmentación del bosque.
Mientras en el mundo la superficie forestal disminuye, en Europa aumenta. Durante los años sesenta y setenta, se generó una gran preocupación por el decaimiento del bosque en el continente, cuando el 45 % de los bosques mostraban síntomas de enfermedad: defoliación, mortalidad de individuos, etcétera. La mayoría de los estudios relacionaron el decaimiento forestal con la contaminación del aire. El proceso era particularmente grave en Europa Central, sobre suelos ácidos, donde las fuertes emisiones de dióxido de azufre hacía bajar el pH del agua de lluvia a valores cuyo promedio podía acercarse a 3.
External impacts
There are some external factors that can cause the deterioration or destruction of the forest ecosystem, including flooding of the dam land to form a reservoir (see chapter on “Dams and Reservoirs”), clearing of the forest for livestock (see chapter “Management of Livestock and Grazing Lands”), shifting cultivation, and its conversion to commercial agriculture (such as rubber, African palm, coffee, rice and cocoa).
The rapid deterioration or complete destruction of many areas of lowland humid tropical forest, characterized by its great diversity of species and environmental complexity, and the difficulties that arise when trying to manage them in a sustainable manner, are of global concern. Although the conservation of these unique forest areas, through the establishment of parks and reserves, is potentially the best way to protect their biodiversity, environmental processes, and the lifestyles of their indigenous inhabitants, only limited areas can be protected in this way. Economic pressures and population growth are intensifying land use that was previously sustainable (shifting agriculture) but is now reaching unsustainable and destructive levels, motivating clear-cut logging, and driving large-scale conversion of forest lands to agriculture and livestock farming, which are generally unsustainable and produce permanent damage to the forest ecosystem. One of the most appropriate ways to protect forests and prevent their conversion to other production-oriented activities, and preserve much of their environmental values, is to manage natural forests so that their production of wood and other products is sustainable, and produces important economic results.
The two critical issues in managing tropical humid forests for timber production are:
In theory, humid tropical forests can provide forest products indefinitely. The reality, however, is that there are few systems that have proven to be sustainable, or that can be applied to the majority of these natural forests with a limited number of species. For this reason, and due to the economic pressures that demand the generation of quick income, only a small portion of the tropical moist lowland forests that are currently being exploited are managed in a sustainable manner.
The most suitable forest management system for lowland humid tropical forests, due to their great diversity of species, is selective exploitation, with which only a small number of trees are extracted per hectare. If this is done carefully, with minimal deterioration of the soil and surrounding vegetation, environmental damage can be limited. Impacts on the biodiversity of the forest and its ability to provide environmental services are minimized (the forest provides four of these services: carbon dioxide fixation, biodiversity, water cycle and land fixation),[8] because large spaces are not created in the forest, as is the case with clearing.
In almost all initiatives that have an impact on natural forests, whether commercial logging, processing industries, or conversion to other uses, for other activities (mining, dam construction, irrigation or industrial development), or decommissioning of forests for rehabilitation or conservation, important social issues arise. Development projects that clear forests for other uses can displace people or reduce their access to forest resources on which they depend for their livelihoods. Commercial logging can destroy resources that are important, locally, to subsistence economies, and can open areas to uncontrolled colonization, causing further environmental degradation and social conflict. Likewise, closing forests for rehabilitation or conservation can reduce the income of the populations around them, depriving them of important nutrients or income-generating products. This closure can cause further degradation. If the pressure on the closed area is too great, conservation and rehabilitation efforts may fail.
Forest dwellers have much knowledge about the qualities, potential utilization, and sustainability of local flora, fauna, and geological resources, often based on knowledge acquired over centuries of sustainable use.
In highland, arid and semi-arid areas, where forage sources are limited, forests and local livestock production systems are usually closely linked; Farmers often adopt mixed livelihood strategies, in which livestock production in the forest plays an important role. For example, in the Himalayan region the productivity of upland agriculture depends mainly on compost and humus collected from forests.
Hunting and gathering, as well as shifting cultivation, have been practiced for hundreds of years in humid tropical forests.
Artisanal fishing in the alluvial zone is important for many of the inhabitants of the lowland forests.
Generally, the social organization of traditional groups is highly adapted to the demands of production systems. Knowledge, both technical and administrative, of these resources can be very useful for technical specialists seeking to intensify or modify production in this or a similar area, that is, to adapt agricultural recommendations to areas where shifting agriculture is currently practiced, or to develop forest management and use models for the forests that will be rehabilitated. As forest-dwelling groups move, their Aboriginal technical knowledge of forest management and use is often lost. Careful evaluation, including real economic analysis, must be made before assuming that current uses of the forest should be abandoned for something "better."
Land tenure issues are almost always a concern in forestry projects. There are often overlapping rights, including state-recognized tenure, customary tenure and/or concessional rights systems in respect of products. In the case of forest-dwelling ethnic minorities, there may be very strong customary rights over forest lands that are constitutionally valid despite authority over these lands having subsequently been transferred to the government.
In many societies, rights to land and trees can be separate, with specific rules for different species. Forest-dwelling groups often have complex ownership regulations regarding forests and products. For example, rights to fruit trees may be different from those that allow individuals to make other uses of forest land, including shifting cultivation. Traditional tenure systems may be more appropriate for the management of fragile lands than options promoted by the State.
Forest closure, or restriction of access and use of resources, affects many population groups differently. For example, landless ranchers may be the most economically harmed by the closure of these areas, because they, unlike landless farmers, cannot obtain "Grass (livestock)" fodder from their own land. Additionally, women may have a much greater workload due to the need to travel much greater distances to find necessary resources; However, local people may not identify this burden as a problem, due to women's lower status in society. If the routes of migratory herders are affected, they may be forced to excessively use other lands outside the project area that are still available, producing negative impacts, both for those lands and for the sedentary groups that depend on them.
Planners are increasingly exploring ways to integrate the needs of local people into forest conservation and rehabilitation initiatives, through promoting proper management of common property resources or joint management systems between government and users. It is important to document existing local management systems, including those that have failed due to increased pressure. In areas of unique biodiversity, other measures have included the creation of protection zones, which generate alternatives for people who traditionally depend on the area to be conserved, or conservation systems have been designed that allow local people to use, in a controlled manner, the protected area. Examples: