From tundra to forests, compare the conditions and biodiversity in each.
The tundra covers arctic regions of the northern hemisphere where the growing season is too short and cold to support tree growth. The word “tundra” actually originates from the Finnish and Russian languages and means “treeless.”
During the winter, temperatures can drop as low as -45°C (-50°F)! The summer, growing season, only lasts about 2 months. As a result, the ground never completely thaws. This “permafrost” makes it impossible for any plants with large roots, like trees, to grow.
Grasses have shallow roots and are quick to grow. This allows them to grow easily in the thawed layer of permafrost during the short summer. It also provides food for animals living in the tundra.
Mosses and Liverworts
Mosses and liverworts are a group of plants that do not have roots or stems. They absorb moisture from the ground by direct contact and provide food for animals.
Reindeer moss, which is a favorite food for reindeer, isn’t a true moss. It’s a lichen—algae growing within a fungus. The fungus absorbs and provides moisture the algae needs to photosynthesize. In return, the algae provides the fungus with energy.
A biome is a community of animals and plants inhabiting a major environmental region. The taiga is the largest of the land biomes, covering most of Canada and Russia. Although the taiga receives moderate amounts of rainfall each year, summers are mild and winters are cold.
The short growing season limits how fast plants can grow. It also limits how much groundwater is available to the trees. Conifers, more commonly known as evergreens, are the dominant trees in the taiga.
Unlike deciduous trees, conifers keep their leaves all year round. Many conifers have leaves in the shape of needles. These needles are covered in a waxy layer, which helps conserve water for photosynthesis.
Deciduous trees are trees that drop their leaves before winter. They’re not as common in the taiga because of the short growing season, but they can be found in particularly wet areas.
Temperate forests usually have 4 distinct seasons—winter, spring, summer and fall. They can be coniferous or deciduous. Coniferous forests are dominated by evergreens. Deciduous forests are dominated by trees that drop their leaves at the end of the growing season.
Temperate forests receive moderate amounts of precipitation but, depending on temperature, it may fall as rain or snow. Because sunlight is limited during the winter months, most of the growing season occurs during the summer when it’s warm.
Redwoods are one of the world’s tallest plant species. Some can reach up to 200-300 feet. Redwoods are conifers and reproduce by seeds that mature in cones. Despite the trees’ immensity, redwood cones are only about 1.5 inches long.
The branches of redwoods can block sunlight from reaching the plants below. You can see many shorter trees and saplings that appear to thrive in the shadow of the redwoods. These trees have adapted to living in the shade.
It’s no surprise that plants growing underneath the forest canopy must be tolerant of shade. Ferns and ivies are plants commonly found on forest floors.
Tropical rainforests are warm and rainy. Because most of these forests are found near the equator, sunlight is plentiful. The combination of warmth, sunlight, and rain means the growing season lasts year round.
As a result, rainforests are some of the most biologically diverse ecosystems in the world. Competition for nutrients and space is fierce, not only between animal species, but between plant species as well.
Notice how crowded the forest floor appears! Plants and fungi compete for every bit of space. The soil is actually very nutrient poor. Nutrients returned to the ecosystem by decomposers are quickly absorbed by plants or washed away by rain.
This particular fallen tree is small. Imagine what would happen if one of the larger trees in the canopy fell! When trees topple, sun tolerant seedlings can grow and take their place in the canopy.
Because the forest floor is crowded and there’s limited access to sunlight, many plants can be found growing on other plants. These types of plants are called epiphytes. Vines, orchids, moss, and ferns are all common epiphytes in the rainforest.
Tree branches and leaves create an umbrella over the rainforest known as the canopy. This is a busy part of the rainforest! It’s home to many birds, primates, and other creatures that survive on the flowers and fruits found there.
Savannas are warm, dry grasslands. They receive moderate amounts of rainfall but most of it falls during the “wet” season. Savannas often have a dry season as well. This, combined with the heat of the sun, means trees do not grow well here.
It also makes the savanna susceptible to wildfires. Despite this, the savanna is home to many species of plants and animals.
Elephants travel in large herds that consume enormous amounts of plants and water each day. Large patches of forests that have been trampled by elephant families are replaced by grasses that are tolerant of the sun's hot rays.
Trees like the acacia have spiny thorns to discourage animals from eating the leaves they need for photosynthesis. Giraffes’ long tongues allow them to tear the acacia leaves without injury, but tree ants also scare away giraffes by biting them.
Zebras’ black and white stripes seems to help protect zebras from predators. Some believe the stripes help zebras blend with the grasses. Others believe the stripes make it difficult for predators to pick a single zebra out of a herd.
Grasses thrive in the sun and are the dominant plant species in grasslands. Established root systems can survive dry periods leading to abundant growth during the wet, warm summer months. They support many species of insects, rodents and grazing herbivores.
Deserts are found in areas with very little annual rainfall. Often the desert air is so dry that a lot of the rain evaporates before it even reaches the ground!
Desert temperatures are often extreme from season to season or even from day to night. Drastic temperatures, dry air and lack of water are large challenges for plants and animals living in the desert.
Sand is created by wind and erosion that break small particles away from rocks. Plant life is too sparse and the air is too dry for a rich soil layer to build here, which is why sand is everywhere.
Settlers traveling through the desert gave these trees their name because they were reminded of the biblical story of Joshua reaching his hands skyward in prayer. These large trees are supported by large roots growing deep into the ground.
Dead or Alive?
Many plants in this desert appear to be dead or dying. But many desert plants have adapted to the lack of water. They may use different strategies for photosynthesizing or may enter a dormant period to survive particularly long droughts.