Reforestation

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Biodiversity on a 15-year-old reforested plot of land.

Reforestation is the process of restoring and recreating areas of woodlands or forest that once existed but were deforested or otherwise removed or destroyed at some point in the past. The resulting forest can provide both ecosystem and resource benefits and has the potential to become a major carbon sink.

1 Natural reforestation
2 Artificial reforestation
3 Contrasted with tree farming
4 See also

[edit] Natural reforestation

Reforestation sometimes occur naturally if the area is left alone without human intervention. In many temperate zones such as the eastern United States, reforestation occurs naturally and fairly quickly as the native hardwood forests are so resilient that they quickly re-establish themselves, given the opportunity to do so.

[edit] Artificial reforestation

In various arid, tropical, or sensitive areas, forests cannot re-establish themselves without assistance due to a variety of environmental factors. One of these factors is that, once forest cover is destroyed in arid zones, the land quickly dries out and becomes inhospitable to new tree growth. Other critical factors include overgrazing by livestock, especially animals such as goats, and over-harvesting of forest resources. Together these may lead to desertification and the loss of topsoil; without soil, forests cannot grow until the very long process of soil creation has been completed - if erosion allows this. In some tropical areas, the removal of forest cover may result in a duricrust or duripan that effectively seal off the soil to water penetration and root growth. In many areas, reforestation is impossible above all because the land is in use by people. In these areas, reforestation requires the planting of tree seedlings, treeplanting. In other areas, mechanical breaking up of duripans or duricrusts is necessary, careful and continued watering may be essential, and special protection, such as fencing, may be required.

One debatable issue in artificial reforestation is whether or not the succeeding forest will have the same biodiversity as the original forest. If the forest is replaced with only one species of tree and all other vegetation is prevented from growing back, a monoculture forest similar to agricultural crops would be the result. However, most reforestation involves the planting of different seedlots of seedlings taken from the area. More frequently multiple species are planted as well. Another important factor is the natural regeneration of a wide variety of plant and animal species that can occur on a clearcut. In some areas the suppression of forest fires for hundreds of years has resulted in large single aged and single specied forest stands. The logging of small clearcuts and or prescribed burning, actually increases the biodiversity in these areas by creating a greater variety of treestand ages and species.

Reforestation need not be only used for recovery of accidentally destroyed forests. In some countries, such as Finland, the forests are managed by the wood products and pulp and paper industry. In such an arrangement, like other crops, trees are replanted wherever they are cut. In such circumstances, the cutting of trees can be carefully done to allow easier reforestation. In Canada, the wood product and pulp and paper industry systematically replaces many of the trees it cuts, employing large numbers of summer workers for treeplanting work.

[edit] Contrasted with tree farming

Reforestation in a strict sense means re-creating natural forests for the sake of the environment, as opposed to tree farming on plantations, which is the practice of regrowing monocultural trees for logging, the manufacture of paper, paper products, and other goods. However, in tropical American nations such as Costa Rica and Panama, the terms "reforestation" and "tree farming" tend to be used interchangeably by many people. It is in these countries that many thousands of acres of ex-cattle pasture are being planted with precious tropical timber species, often with the help of generous local government incentives. Unlike in the US and Canada, where trees are planted on a massive scale mainly for wood pulp and paper, in Costa Rica and Panama, among other nations in Central America, reforestation/tree farming is mostly being done in order to one day reap the benefits of the use of the timber.

For example, in just 20 years, a teak plantation in Costa Rica can produce up to about 20 m³ of wood per hectare [1]. As the natural teak forests of Asia disappear, the prices commanded by plantation-grown teak grow higher every year. Other species such as mahogany grow slower than teak in Tropical America but are also extremely valuable. Faster growers include pine, eucalyptus, and gmelina.

Often, trees are planted with several species intermixed, thus blurring the traditional distinction between reforestation (using a mix of all native species) and tree farming (using one species as a controlled monoculture). Further blurring the distinction is the fact that reforestation, if done properly (ecologically), also provides other benefits in addition to the financial returns, including restoration of the soil, rejuvenation of local flora and fauna, and the capturing and sequestering of 38 tonnes of carbon dioxide per hectare per year.