Why don’t trees grow in the tundra? The tundra may seem harsh and inhospitable, but it is home to various plants, animals, insects, and other organisms.
Even though humans are in scarce supply in the tundra, some have established their homes there.
Which has prompted many to question why there aren’t any trees there. Keep reading to understand more about tundra and why trees can not survive there.
Low temperatures and limited growth seasons make it difficult for trees to grow in the tundra.
What Is Tundra?
Tundra is a biome in physical geography where low temperatures and short growing seasons hinder tree development.
The name tundra is derived from the Kildin Sami word tndâr, which means “uplands” or “the treeless mountain region.”
Tundra characteristics include:
- Freezing weather
- Biodiversity is limited.
- Structure of simple vegetation
- Drainage restrictions
- Short growth and reproductive season
- Dead organic material provides energy and nutrition.
- Large population fluctuations
Additionally, Tundra is classified into three types: Arctic tundra, alpine tundra, and Antarctic tundra, as discussed below:
Arctic tundra is found in the extreme north of the Northern Hemisphere, north of the taiga belt.
The Arctic tundra is home to several nomadic reindeer herders, including the Nganasan and Nenets in the permafrost region.
Arctic tundra has a 50-to-60-day growth season. Summer temperatures vary from 37 to 54F, while winter averages -30 F. Scandinavian tundra winters average 180F.
The tundra receives only six to ten inches of precipitation yearly (mainly snow).
Due to the severe Arctic environment, these locations have seen little human activity, despite being rich in oil and uranium. This is changing in Alaska (USA), Russia, and other places.
Because of permafrost, global warming threatens the Arctic tundra. In the summer, just the surface of permafrost melts.
Permafrost thawing might influence which species survive in human periods (decades or centuries).
Antarctic tundra is found in Antarctica, South Georgia, the South Sandwich Islands, and the Kerguelen Islands.
Antarctica is too cold and dry for flora, and most of it is covered in ice.
The Antarctic Peninsula has rocky soil that supports Tundra.
Antarctic flora consists of between 300 and 400 lichens, 100 mosses, 25 liverworts, and 700 terrestrial and aquatic algae species that thrive on exposed rock and soil along the continent’s coast.
In contrast to the Arctic tundra, the Antarctic tundra lacks vast animal fauna due to the continent’s geographical isolation.
Sea animals and birds, such as seals and penguins, live along the beach, and humans have brought small mammals such as rabbits and cats to some of the sub-Antarctic islands.
Alpine tundra is found at high altitudes on mountains across the globe where trees cannot grow.
The growth season lasts around 180 days. The temperature at night is generally below freezing.
In contrast to the arctic tundra, the alpine soil is well drained. The plants are quite similar to those found in the Arctic and include the following:
- Dwarf trees, tussock grasses, heaths, and small-leaved shrubs.
Animals that live in alpine tundra are also well adapted:
- Marmots, pikas, sheep, mountain goats, and elk are examples of mammals.
- Beetles, springtails, butterflies, and grasshoppers are examples of insects.
- Birds: grouse-like birds
Why Don’t Trees Grow in the Tundra?
Tundra is derived from the Finnish word Tunturi, meaning “treeless plain” or “barren ground.” But why is it treeless?
The following are some of the reasons why there are no trees in tundras:
1. Tundra has a Freezing Climate
The tundra is the world’s coldest biome. Winters are long, cold, and dark. There are numerous weeks when the sun does not rise.
The average winter temperature is below -34°C and may reach -70°C under challenging situations.
The winter snow cover melts over the summer. This causes permafrost, or permanently frozen soil, which refers to deeper sections of the earth that stay frozen.
Permafrost depths may range from 10 to 35 inches making it difficult for trees to grow there.
2. Tundra has a Short Summer Season
The typical summer temperature is between 3 and 12 degrees Celsius.
However, it only heats up for two months of the year. During this season, the sun shines about 24 hours a day.
The fierce and practically continuous wind is one of the most revealing elements of the arctic environment.
It also has a short summer season, which is notable not so much for its slightly higher temperatures because daylight may linger almost 24 hours at a time.
Because of the short seasons, tree growth is stunted.
Note: The tundra climate is known by several names, one of which is "the region of the everlasting night" because of its lengthy winter darkness.
3. It has a Little Precipitation
Why are there no trees on tundras?
Tundra climates have low precipitation amounts. The tundra receives less than 15 inches of rain each year, making it the driest desert habitat.
Melting snow and ice isn’t just enough for tree growth. It only causes decay to form a thin coating of flammable material on the land’s surface.
Note: This unprecedented absence of rain also poses a fire threat. A big fire occurrence occurs on the tundra once every 100 years on average.
Nothing can be done to put out a massive fire on the tundra since there are no water supplies. The tundra’s role as a natural carbon dioxide sink also encourages burning.
4. The Permafrost In the Tundra
The majority of tundra soils are classed as Cryosols.
Cryosols are mineral soils that occur in permafrost-covered environments; consequently, they are also known as permafrost soils.
Permafrost is defined as ground that has remained at or below 0 degrees Celsius for two years or longer.
Cryosols have an active layer that builds and thaws above the frozen ground on a seasonal basis.
How Does Permafrost Prevent Trees from Growing?
Permafrost in the tundra also hinders root penetration into deep soil layers. This effectively blocks biological activity in the lower soil layers.
Because permafrost is frozen for ages, water becomes a limiting element for plants.
Tundra soils have a minimal depth to hold water and only for a short time during the growing season.
This worsens water scarcity in tundra locations.
Note: The numerous freeze-thaw cycles associated with permafrost soils cause cryoturbation, sometimes known as 'frost churning.'
Frost churning restructures the soil matrix, resulting in uneven or fragmented soil horizons, organic intrusions, orientated rock pieces, and silt-enriched layers.
5. Soil in Tundra has Deficient Nutrients
Do trees grow in the tundra? No, Tundra soil is similarly deficient in nutrients.
Cryosolic soils in the tundra are made of unconsolidated parent materials such as aeolian, alluvium, glacial till, organic and colluvium. The pH of cryosolic soils is heavily influenced by parent material.
The Cryosolic soil order is divided into three major groups:
Turbic, Static, and Organic.
They are determined by two primary criteria: the presence or absence of cryoturbation and the parent material’s composition.
Almost all cryosols have some ice buildup, such as layers, ice lenses, and wedges; soil texture is one of the determining elements for the quantity of ice in mineral soils.
How Does Cryosolic Soil Prevent the Growth of Trees?
The thickness of the active layer in cryosolic soils is controlled by soil texture, plant cover, moisture regime and the organic surface layer.
The active layer is essential to the tundra environment because it supports all biological activity while protecting the underlying permafrost.
Nitrogen, potassium, and phosphorus are often low in cryosolic soils because they are bound within the surface organic matter.
Tree development is limited in cryosolic soils due to low nutrient levels.
Note: Organic carbon may be found in large amounts in cryosols, particularly Turbic ones.
Cryosols are also major carbon sinks in the present climate, which is critical for global climate management.
6. It Has Frost-Molded Landscapes
The tundra terrain features distinct microtopography due to cryoturbation, commonly referred to as patterned ground.
Ground material forms geometric shapes due to the strong frost heaving associated with the season freeze-thaw cycle.
How Do Frost Molded Landscapes Form?
The freeze-thaw cycle will shift and sometimes sort soil particles (including large rocks).
Because of variances in stone size and freeze-thaw frequency, the ground has a variety of patterned formations such as circles, polygons, and stripes.
These formations are sorted and unsorted material and range in diameter from a few centimeters to several meters.
Frost boils, for example, are a frequent nonsorted circles characterized by barren centers of mineral soil with plants populating the inner circle portions.
Hummocks are tiny mounds above ground that emerge through differential frost heaving and are frequent in locations with permafrost and seasonally frozen ground.
Hummocks are often found in clusters, resulting in a hummock-hollow (non-hummock area) pattern throughout landscapes.
Trees struggle to grow in this kind of terrain.
7. Invertebrates Found in Tundra Soil
Herbivory, decomposition, nitrogen cycling, and pollination are all important ecological services provided by invertebrates.
Tundra soil invertebrates must adapt to the extreme circumstances of the environment.
Hence, many have life histories that enable them to sleep most of the year.
In the Arctic, there are an estimated 2000 distinct species of soil invertebrates, the majority of which are mites, springtails, and enchytraeids.
These three invertebrate groups are known to have enormous worldwide populations.
Mites are significant decomposers and live in a variety of habitats. Mites are typically overlooked due to their tiny size; nonetheless, they are varied and live in various organic detritus.
Springtails do not directly affect organic matter breakdown in soil but substantially affect soil microbial populations. Making it harder for trees to grow.
Note: Enchytraeids, like springtails, do not degrade organic waste since they feed on live stuff.
Enchytraeids may also significantly impact the bacterial population and play a vital role in nutrient cycling, particularly nitrogen mineralization.
Why don’t trees grow in the tundra?
The tundra is the most northern plant-growing biome. The permafrost prevents deep root development and hence tree growth.
Because roots cannot extend in permafrost, tree development is hampered. Plant growth is hampered by the land’s short life cycle.
Climate and soil conditions also influence tree size and shape in the tundra. The Great Plains, formerly covered with trees, are now hilly. Because the sun melts the snow, tundra trees are sparse.
Thanks for reading!