Question

Terrestrial biomes such as tundra, taiga, temperate forests, and tropical forests are distributed in different parts of the world. Which one of the following options best represents the environmental factors that determine the distribution of these biomes?

• A. Temperature and elevation
• B. Rainfall and wind
• C. Temperature and rainfall
• D. Fire and elevation

Hint:

Biome maps, like the Whittaker biome diagram, are built from just two climate axes.

Answer 1

The Correct Option is C

This question checks whether you know the two climate variables ecologists use to draw the world's biome map. Let's go through each option.

1. Temperature and elevation: Elevation changes climate locally, it gets colder as you climb a mountain, but elevation is not one of the two standard axes used to separate biome types across the globe. It explains local zonation, not the big picture.
2. Rainfall and wind: Rainfall is one of the right factors, but wind is not part of the classic biome model. Wind affects things like tree shape and water loss locally, but is not used to draw biome boundaries.
3. Temperature and rainfall: This is the standard pair. Plotting mean annual temperature against mean annual rainfall on a graph (the Whittaker biome diagram) sorts land area into tundra, taiga, temperate forest, tropical forest, grassland, and desert.
4. Fire and elevation: Fire shapes some biomes such as savanna at a finer scale, and elevation drives local alpine zones, but neither is the main pair of factors used to separate biomes worldwide.

The correct pairing is temperature and rainfall, since together they explain why the same latitude can have desert in one place and rainforest in another, depending on how much rain falls.

Let's summarize:

• Terrestrial biomes are mapped along two climate axes: temperature and rainfall.
• Elevation, fire, and wind matter, but only as local modifiers, not the primary global factors.

So the environmental factors that determine biome distribution are temperature and rainfall.