A forest is a complex, biodiversity-rich, self-regenerating ecosystem, consisting of soil, water, microclimate, and a wide variety of plants and animals in mutual coexistence, on a piece of land. Trees are naturally regenerated in ‘natural forests’. Natural Forests have high biomass density, i.e., they sequester more carbon and have ‘continuous plant growth’.
A natural forest is made up of many layers, i.e., it is multi-storey. The main layers of all forest types are the forest floor, the understory and the canopy. The ’emergent layer’ exists in tropical rainforests. Each layer has a different set of flora and fauna, depending upon the availability of sunlight, moisture and food. Thus, natural forests are biologically diverse, and home to many rare species threatened species, and endangered species’. ‘Natural Forests’ host more than 70% of terrestrial biodiversity and are critical for life on the planet.
Forests grow around the world, from the equator to polar regions. Different climates have different kinds of forests e.g., in cold climates conifers dominate, in temperate and tropical climates flowering plants dominate. Different rainfall also has different kinds of forests. No forest exist in deserts, just a few xerophytes are dispersed.
Anthropogenic factors (human impact on the environment) are encouraging logging, forest fires, acid rain, invasive species introduction, shifting cultivation and deforestation. Excessive deforestation reduces biodiversity, affect natural forests and also indigenous species that rely upon old-growth forest habitat. According to the United Nations Food and Agriculture Organisation report-2010, ‘agriculture expansion is increasing deforestation’.
In 1997, the World Resources Institute recorded that only 20% of the world’s original forests remained in large intact tracts of undisturbed forests, and among these, more than 75% of forests are found in three countries: boreal forests of Russia and Canada and the rainforest of Brazil.
Plantation programmes are being carried out globally, along with conservation of natural forests, to protect biodiversity, to ‘change climate change’ by increasing the ‘carbon sink area’, for soil and water conservation, and for industrial wood production. However, according to this article, “Plantations are most likely to contribute to biodiversity when established on degraded lands rather than replacing natural ecosystems and when indigenous tree species are used rather than exotic species.”
But, new forests or plantation forests or anthropogenic forests are not completely equivalent to natural forests or old-growth forests in terms of species diversity, resilience and carbon capture. Plantations, going globally, are usually monoculture, that is, large saplings of the same species are planted across a given area, whereas a natural forest contains a more diverse range of tree species. In a true sense, single-species plantation forests are not natural forests.
Plantations of single tree species may have very different ecosystem characteristics than do many native forests. Monoculture plantations have very little biodiversity, require human intervention and use of large amounts of herbicides and pesticides. They have ‘less biomass density‘, sequester less carbon and have a single storey. These are managed forests, in which the trees of the same age, and generally of the same species, are planted; this is done chiefly to maximise the production of the wood fibre.
Plantations may include tree species that would not naturally occur in the area e.g. hybrids and genetically modified trees.
In ecological terms, plantations are always young forests. What does this mean? Such forests do not contain the type of growth, soil or wildlife which is usually seen in of old-growth, natural forest ecosystems.
Plantation forests are the cause of numerous environmental problems in many countries because of mostly single-species dominance. For instance, in Indonesia, where palm oil plantation is causing a threat to many species, including red apes or orangutans, only 15% of native species can survive the transition from primary forest to a plantation. In Indonesia, multinational pulp companies have harvested large areas of natural forest. About 50% of the 1.4 million hectares of pulpwood plantations in Indonesia have been established on what was previously natural forest land.
Single species plantations have a negative impact on biodiversity, communities, and local economies which includes, loss of biodiversity, depletion of water sources and water pollution from pesticides and agrochemicals used.
Annually, September 21st is observed as the ‘International Day of Struggle against Monoculture Tree Plantations’.
The United Nations Food and Agriculture Organisation projects a huge increase in monoculture tree plantations: between 40 and 90 million hectares will be planted by the year 2030.
So, next time, when you opt for plantation, first ensure that it is not going to be a monoculture. This step will be helpful to save the depleting biodiversity and will maintain the ‘high biomass density’ of the ‘future forest’ so that they will be able to sequester more carbon and will help to ‘change climate change’.