7 Types of Forest Ecosystem Explained
Types of forest ecosystem are; tropical, temperate, boreal, old-growth, second-growth, natural, and artificial forests. They are classified based on climatic conditions, human influence, and mode of occurrence.
This article discusses the types of forest ecosystem and their characteristics;
-Types of Forest Ecosystem based on Climatic Conditions
-Types of Forest Ecosystem based on Human Influence
-Types of Forest Ecosystem based on Mode of Occurrence
Types of Forest Ecosystem based on Climatic Conditions
1). Tropical Forest as one of the Types of Forest Ecosystem
Tropical forest is one of the most common types of forest ecosystem. It includes forested lands that occur in areas with tropical or equatorial climatic conditions; such as warm temperature, high humidity and precipitation [2].
Tropical forests are estimated to occupy about one-tenth of the total land area on Earth. They occur between the Tropic of Cancer and the Tropic of Capricon; which are at 23°27′ N and 23°27′ S of the equator respectively [14].
The geographic span of tropical forest ecosystem is vast. It extends from Sub-Saharan Africa to Southern Asia and Central America.
Temperature conditions in this type of forest ecosystem, ranges between 20-31°C (or 68-88°F).
In terms of climatic conditions, the tropical forest is very stable. It is also a favorable habitat for a great variety of organisms.
At least 50% of all plant and animal species on Earth is estimated to occur in tropical rainforests [7]. The Amazon Forest (which is a tropical forest in Central America) is believed to contain up to 10% of all species on Earth.
Dry and rainy seasons occur every year in a tropical forest. The rainy seasons involve rainfall, that ranges from 79 to 394 inches per annum.
The energy pyramid in a tropical forest is very active, as a result of the high levels of biodiversity. Processes like feeding and biodegradation occur on a large-scale. As a result of rapid biodegradation, tropical forest soils may not have high nutrient concentration.
Also, much of the biodegradation occurs on the surface of the ground, and may not extend deep into the subsurface. For this reason, tropical forest vegetation is adapted to produce shallow roots in order to access nutrients. Their weight is supported by trunks and other adaptive structures. Tropical forest soils are also usually acidic [6].
There are various sub-types of tropical forests. They include; tropical dry, tropical moist, mangrove, rainforest, montane and evergreen forests.
-Tropical Dry Forest
Tropical dry forest occurs in equatorial areas that are susceptible to drought and desertification.
In these forests dry season occurs for a relatively-long period of the year, with little rainfall for about four to six months. As a result, deciduous trees dominate the vegetation, along with drought-resistant shrubs. Most of these plants are without leaves for a good part of the year.
Prolonged dryness and overgrazing in tropical dry forest can transform this ecosystem to a grassland or savanna.
-Tropical Moist Forest
Tropical moist forest has more rainfall than tropical dry forest, but less than evergreen forest.
They occur in locations further from the equator than evergreen forests, and are conducive for the survival of deciduous trees with evergreen characteristics. Tropical moist forest can have different topographic features, occurring in level, undulating and mountainous regions.
-Mangrove Forest
Mangrove forest is a type of forest ecosystem that occurs in coastal regions [1]. Here, the soil and vegetation are in contact with brackish water (saltwater and freshwater mixture), and are adapted to survive under such conditions.
-Rainforest
Rainforest is the type of tropical forest which has the most rainfall. Annually, at least 2m of rainfall is experienced in rainforests. As a result, they have significant biodiversity and vegetation growth.
-Evergreen Forest
Evergreen forest is a type of tropical forest that is dominated by trees which do not shed or lose all their leaves at any time during the year. Such trees are called ‘evergreen’ trees.
-Montane Forest
Montane forest (or cloud forest) is a type of tropical forest that typically occurs in high-altitude, mountainous regions. The forest is usually covered by fog or mist from condensing water vapor, and has relatively-short trees.
-Subtropical Forest
Subtropical forest is a type of forest that has warm and dry climatic conditions. They usually contain a significant number of coniferous trees.
Tropical forest ecosystems are being threatened by human activities.
Deforestation for agriculture, biofuel and bioenergy resources, as well as raw materials, has led to severe environmental degradation and loss of tropical forests [13].
Various species of plants and animals in tropical forests also face the threat of extinction due to global warming, climate change, and hunting activities.
2). Temperate Forest as one of the Types of Forest Ecosystem
Temperate forest occurs in mid-latitude regions, including parts of Europe, Asia, and North America [9].
One of the characteristics of this type of forest ecosystem is its seasonality. Temperate forests experience up to four seasons annually.
The temperature conditions here may vary widely, although the average range falls between -22°F and 86°F (-30°C and 30°C). Annual rainfall is between 75cm and 1.5m (30 and 60 in).
Biodegradation in the temperate forest is not as rapid as it occurs in the tropical forest. Moderate decomposition rates combined with high organic content and high amounts of precipitation, results in fertile soil.
Temperate forest soils are generally rich in nutrients and organic matter, and support the growth of a variety of plant species [11].
The locations of temperate forest range from mountainous to coastal regions. They occupy up to 16% of the total forested land area on Earth. Tongrass forest is believed to be the largest temperate forest on Earth, with a span of nearly 17 million acres.
A significant number of animal and plant species occur in temperate forests. These include oak, hickory, cottonwood, hemlock, maple, elm, squirrel, bear, deer, and partridgeberry. Some temperate species like the northern spotted owl are facing threat of extinction, mostly as a result of human activities.
Types of temperate forest ecosystem are; temperate deciduous, temperate coniferous, and temperate meridian. However, the two most-known types are temperate deciduous and temperate coniferous.
-Temperate Deciduous Forest
Temperate deciduous forests are dominated by deciduous trees, which shed their leaves in winter and autumn [5]. Shedding of leaves is a biological adaptation that serves as a means of energy conservation for the trees during periods of less productivity.
Oak, birch, elm, and maple are examples of vegetation in this ecosystem. Aside deciduous trees, firs and pines are some coniferous species found in temperate deciduous forests.
Locations of temperate deciduous forests include parts of Eastern and Western Europe, Japan, China, Canada, and the United States.
When leaves are shed, they fall to the forest floor and decompose. Temperate deciduous soils are fertile.
The forest canopy or cover is less dense than tropical forests, and sunlight can penetrate close to the ground. As a result, shorter plants and shrubs grow significantly, using solar energy to produce their own food through photosynthesis [15].
Precipitation in this ecosystem occurs in form of snow and rain, which may range from 30 to 60 inches per annum. Animals here include deer, squirrel, fox, wolf, bear, woodpecker and hawk.
-Temperate Coniferous Forest
Temperate coniferous forest is dominated by coniferous trees.
They are also referred to as temperate evergreen or temperate rainforest (however some studies may regard these as different types of temperate forests).
Compared to temperate deciduous forests, these forests occur in colder regions. Some locations of temperate coniferous forests include Southern Japan, Northwestern Americas, Southwestern South America, Northwestern Europe and New Zealand.
Temperate coniferous forests are called ‘temperate rainforest’ because they receive large amounts of rainfall each year, ranging between 50 and 200 inches, although other estimates may vary.
Like temperate deciduous forest, the soil here is very fertile. Combined with high rainfall, trees tend to grow rapidly, and most do not shed all their leaves at any time during the year.
Fir, spruce, cypress, redwood, pine and cedar are some trees in this ecosystem. Animals here include marmot, deer, spotted owl, bear, and elk.
The main period of growth (growing season) in temperate forests ranges from 140 to 200 days. Temperate species tend to conserve their energy through hibernation and other adaptive mechanisms during the inactive months.
Human activities have led to massive loss of temperate forests through deforestation.
3). Boreal Forest as one of the Types of Forest Ecosystem
The boreal forest, also called the taiga, is a cold forest ecosystem that typically occurs between latitudes 50°N and 70°N, in the Subarctic region [8].
Geographic locations of boreal forest include Northern Asia, Siberia, Scandinavia, Canada and Alaska. A major portion of the boreal forest is estimated to occur in Scandinavia and Siberia.
Some studies describe the boreal forest as the largest terrestrial ecosystem or biome on Earth [12].
Temperature conditions in boreal forest are extremely cold, ranging between -40°C and 20°C. As a result, a good portion of the soil is frozen all through the year. Such permanently frozen soil is called permafrost.
Seasonality is also a feature of boreal forests, with short summer and long winter periods occurring in alternate cycles each year.
Precipitation in the boreal forest is mostly in the form of snow, and may range from 15 to 40 inches (40 to 100 cm) per annum.
Because of the frozen nature of soil and the slow rate of biodegradation, boreal forests play a role in natural carbon capture and storage [3]. Carbon is captured as organic matter is buried under frozen soil. This means that boreal forests are important as a natural tool for mitigating climate change.
Soil conservation in boreal forests, is performed naturally by biomass (organic matter) and glaciers. The thin layer of soil which is not frozen, has low-fertility and high acidity [10].
The growing season in boreal forest is relatively short, lasting about 130 days.
Due to the melting of glaciers, when temperatures grow warmer, the soil in boreal forests becomes waterlogged and swampy, and trees may collapse due to loss of stability. This means that ozone layer depletion, climate change and other causes of rapid temperature rise, cause the degradation and loss of boreal forests.
Compared to tropical forests, the boreal forest ecosystem has low biodiversity. There are various factors that contribute to this. They include harsh climate, short growing season, scarcity of food resources for long periods of the year, and thick forest canopy that prevents enough sunlight from penetrating the forest.
However, a significant number of plant and animal species still live in boreal forests. These have special adaptations to survive under the harsh conditions, such as body insulation, hibernating habits, and specialized root systems.
Coniferous trees are common in boreal forests, such as fir, spruce, pine, willow and poplar. Deciduous trees also occur.
Animals in boreal forests include lynx, bear, wolf, fox, moose, deer, hawk, caribou, wolverine, bat, and shrew. Many of these animals are migratory, while others are hibernators.
Types of boreal forests are open canopy and closed canopy boreal forests.
-Open Canopy Boreal Forest
Open canopy boreal forest has less-dense vegetation.
It occurs at higher latitude than closed canopy forest, and experiences harsher climatic conditions. As a result, biodiversity is relatively-low.
-Closed Canopy Boreal Forest
Closed canopy boreal forests have denser vegetation than open canopy forests. As a result, less sunlight is able to penetrate through the canopy of trees.
This type of boreal forest occurs at lower latitude than open canopy boreal forests, and experiences less harsh climatic conditions.
The relatively warm climate allows more species to survive in closed canopy boreal forests, leading to higher biodiversity. Soils here are also more fertile.
Like other types of forests, boreal forests are affected negatively by human activities that have led to degradation and deforestation of these forests.
Types of Forest Ecosystem based on Human Influence
The types of forest ecosystem based on human influence are old-growth and second-growth forests.
4). Old-Growth Forest as one of the Types of Forest Ecosystem
As the name implies, old-growth forests are forests that are dominated by their original vegetation [16].
This type of forest is also called virgin forest, primary forest, first-growth forest, primeval forest or seral forest.
Trees and shrubs in old-growth forests may be hundreds or thousands of years old. As a result, the vegetation in such forests is highly adapted to the ecologic conditions that are prevalent in their environment.
The forest canopy has gaps that form as a result of the natural spacing of trees and the occasional death of some of these trees. This pattern is called a natural open canopy pattern.
Biodiversity in old-growth forests is made up of highly-adapted native species with a broad range of characteristics. Soils are also richer in organic matter and have undergone more development in structure and composition.
5). Second-Growth Forest as one of the Types of Forest Ecosystem
A second-growth forest is a type of forest ecosystem that is dominated by regrown vegetation, that is not the original vegetation of the forest.
The regrowth of vegetation in second-growth forests may occur naturally or artificially.
In some cases, trees and shrubs regrow naturally after the original vegetation has either died or been removed. This can occur when land that has been formerly deforested, is abandoned and left to reforest naturally over time.
However, in most cases, regrowth is human-induced. In such cases, the second-growth forest is a result of reforestation and revegetation projects.
Because second-growth forests do not have a long natural history of uninterrupted growth cycles for hundreds or thousands of years like old-growth forests, they are less-developed in terms of ecology.
Second-growth forests are not ecologically complex like old-growth forests. They lack the degree of biodiversity and specialization that is attained from long-term biological adaptation.
Many species in second-growth forests are not native, but rather have been introduced by humans into the ecosystem, from a different biome.
The trees in second-growth forest are spaced based on human estimates, and tend to be closer to one another than those in old-growth forests. As a result, the canopy is usually denser and closed, compared to the open canopy structure of old-growth forests.
Trees in second-growth forests are also much younger and thinner than those in old-growth forests.
A comparison between old-growth and second-growth forests is given in the table below;
| Old-Growth Forest | Second-Growth Forest |
| Has undergone a long period of natural evolution | Has not undergone natural evolution |
| Biodiversity is relatively high | Biodiversity is relatively low |
| Species are highly specialized and adapted | Species may not be adapted |
| Native species are dominant | Most species are not native |
| Trees are older and thicker | Trees are younger and thinner |
| Soil is more developed and has higher organic content | Soil is less developed, with lower organic content |
| Forest canopy is open and less-dense due to natural evolution | Forest canopy is closed and denser than old-growth canopies |
| Human influence on the ecosystem is relatively low | Human influence is relatively high |
| Higher available energy, productivity and sustainability | Energy, productivity and sustainability are lower than old-growth forests |
Types of Forest Ecosystem based on Mode of Occurrence
Based on mode of occurrence, the types of forest ecosystem are natural and artificial.
6). Natural Forest as one of the Types of Forest Ecosystem
A natural forest is a type of forest ecosystem that has originated and reproduced naturally.
It is usually comprised of indigenous species of plants and animals, although some immigrant species may also be present.
What defines a natural forest ecosystem is the natural occurrence of reproduction, migration, evolution, adaptation and survival in these forests. Such processes all occur without any human intervention.
Most of the major types of forest ecosystem like tropical, temperate and boreal, are natural forests.
7). Artificial Forest as one of the Types of Forest Ecosystem
Artificial forests are forests whose production and occurrence have been facilitated by humans.
The ecological composition and structure of artificial forests are different from those of natural forests and can be used to distinguish the two types from each other [4].
Some artificial forests are second-growth forests whose origins are natural; but have experienced deforestation and loss of biodiversity in the past. Other artificial forests have manmade origins. These are called manmade forests or plantations.
The goal of artificial forestry is to recreate the ecological characteristics and functions of forest ecosystems. Artificial forests may comprise of both native and non-native species.
Reforestation, revegetation, soil conservation, water conservation, and sustainable farming are all related and important to artificial forestry.
Conclusion
The (sub-types and) types of forest ecosystem discussed in this article are;
- Tropical Forest
2.Tropical Dry Forest
- Tropical Moist Forest
- Mangrove Forest
- Rainforest
- Evergreen Forest
- Montane Forest
- Subtropical Forest
- Temperate Forest
- Temperate Deciduous Forest
- Temperate Coniferous Forest
- Boreal Forest as one of the Types of Forest Ecosystem
- Open Canopy Boreal Forest
- Closed Canopy Boreal Forest
- Old-Growth Forest
- Second-Growth Forest
- Natural Forest as one of the Types of Forest Ecosystem
- Artificial Forest
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