Tundras are typically cold and dry. Below the topsoil is permafrost which is permanently frozen ground. There’s also not many nutrients to support animal and plant life.
Deserts are typically hot during the day and during the night some can drop down below 32º F. They’re also not very humid which makes it feel hotter
Savannas are large and open grasslands that are filled with animals. If an animal is an herbivore it will most likely be eaten by a predator. Savannas are typically warm all year. The largest Savannah can be found in Africa
The Tropical Rainforest has three different layers. The canopy, understory, and the forest floor. The canopy is on top of all the trees which are usually over 100 feet tall. The forest floor is typically the most quiet layer of the rainforest.
Temperate forests usually get lots of rain. They also have four seasons. The temperature is typically between -20 degrees F and 90 degrees F. The soil is fertile meaning rotted leaves and other things that decay provide a rich, deep soil which is good for tree roots.
Rivers have four key factors. Flow, light, temperature, and chemistry. Flow has to do with the amount of water and strength