There is a lot of difficult terminology in nature conservation, which can make it uninviting for people without a background in Nature conservation. Therefore, I am starting a series where I explain this difficult terminology, I explain it short and easy so everybody can understand them. Regardless of the fact if you studied in nature conservation or not. Today will be part 1 of the ‘explained in 200 characters’ and it will be about forests. This is my favourite biome. My bachelor was forest-related. And so is the master I am currently doing!
So today I will be explaining a lot of things that are relevant for the forest biome. This biome is one of the 5 major ones in the world and consists of all forest types. These are the boreal, temperate and tropical forests. All these forest together are cover approximately 30% of the earth’s surface! Before I dive into the separate forms, explaining the difference, I will give you a general definition of a forest. ‘An environment that is covered by trees that are at least five meters high and cover an area of at least 0.5 hectares and a canopy cover of at least 10%’.
Forest are an important biome as they provide many different resources for humans. Such as resources, but also additional services. Such as water purification and carbon sequestration. And they provide supportive environments for many different plants and animals. Now let’s get started!
Different types of forests explained
As mentioned, there are 3 different types of forests; temperate, boreal and tropical. let’s start with the first one. Boreal forest; growing in high-latitude environments, with freezing temperatures for 6 to 8 months per year. And is mostly made up of cold-tolerant coniferous species such as spruce and fir. Temperate forest; growing between tropical and boreal regions. most notable because they go through four seasons. Leaves change colour and drop in autumn and grow back in the spring. This adaptation allows plants to survive cold winters. Tropical rainforest; growing around the equator and can be characterized in two words; hot and wet. Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year and average annual rainfall is no less than 1,680 mm. There is no real dry season.
So, that tropical rainforest is wet is clear. But did you know that rainforests also exist outside of the tropics? Rainforest; are characterized by high and continuous rainfall. The minima range from 1700 to 2500 mm per year, depending on the region. It needs to be equally divided over the months. Following these requirements, you can find several different regions of rainforest in the temperate region. Such as in Southern Norway, the pacific northwest in USA, Australia and New Zeland.
So far I have explained the three main different forest types. Let’s zoom in a bit into the tropical rainforest, these areas are under high pressure due to human demand. This resulted in three different forest types within the tropical rainforest. Due to the actions of humans. Let’s have a look at them. Primary forest; forests of native tree species, where there are no clearly visible indications of human activities and the ecological processes are not significantly disturbed. Secondary forest; forests that regenerate on primary forests which have been cleared by natural or man-made causes, such as agriculture, ranching or logging. Plantation forest; a type of managed forest in which the trees are planted (instead of naturally regenerated), of the same age and generally of the same species. Intended to maximize the production of the wood fibre.
Threaths for the forest
The forests are facing many threats these days, mostly due to human demand. In the amazon, big area’s are being cleared for agriculture, mostly soya, and grazing of cattle. And in Asia for the production of palm oil. In this part the difference between deforstation and degradation will be explained. As wel as for what happens due to the fragmentation of the forest.
Due to deforestation; the permanent removal of trees to make room for something besides the forest. This can include clearing the land for agriculture or grazing or using the timber for fuel, construction or manufacturing. Forest are under great threat, but not only the permanent removal is harming the forest.
But also degradation; a process in which the biological wealth of a forest area is permanently diminished by some factor or by a combination of factors. This reduces the quality and quantity of the services the forest can deliver. But also reduces the amount of suitable habitat for wildlife.
Not only causes this the reduction of a healthy forest, but it also creates fragmentation; the breaking of large, contiguous, forested areas into smaller pieces of forest. Typically these pieces are separated by roads, agriculture, utility corridors, subdivisions, or other human development. There are two ecological concepts we use to explain the effects of forest fragmentation. Which I will explain according to the ‘explain in 200 characters’ idea and then followed by an example. As this is a bit more complicated.
The edge effect explained
The first one we are going to talk about is edge effect; increase the proportion of habitat edges in relation to the total area. In other words, any given point within the fragment of land is, on average, closer to an edge.
What is dangerous about this is, that not only the total area is reduced, also the patch size of each forest and increased isolation of the forest patches. This will influence both the animal and plant species within a forest. Large mammals might not be able to survive anymore, as they require a bigger forested area to gather enough food. While tall trees suddenly have to deal with an increased amount of elements, which they are unable to survive. The edge of the forest is also called a transition zone and is an unfavourable habitat for many species. Due to the edge effect, there is a great ratio of these transition zones. And an recuded amount of suitable habitat.
Island biogeography explained
The Island biogeography theory has its applications in conservation biology, the field I am studying in. Island biogeography: examines the factors that affect the species richness and diversification of isolated natural communities, determined by immigration and extinction. Using the degree and length of isolation and the size of the island.
This theory started with an island-mainland, but also perfectly fits with natural areas on the mainland. Generally, it is expected to find a higher number of species in a natural area, closer to another natural area. There is also an expected higher number of species correlated to the size of the natural area. The bigger the natural area, the more species. As larger areas contain larger habitat areas which have more opportunities for different varieties of habitats. Variety of habitats attracts a variety of species.