The main thing that determines what type of biome can exist in a region is its climate —especially the long‑term pattern of temperature and precipitation.

Core idea (the super‑short version)

  • Warm vs. cold (average temperature).
  • Wet vs. dry (amount and seasonality of rainfall or other precipitation).

Different combinations of these two put you into different biome “zones” (desert, grassland, forest, tundra, etc.).

The key drivers

1. Climate: temperature and precipitation

These are the big two:

  • Temperature : Controls whether water is liquid or frozen, how long growing seasons last, and what plants can survive.
  • Precipitation : How much water is available and when it arrives (steady year‑round, monsoon bursts, or rare storms).

Ecologists often sketch biomes on a graph of average annual temperature vs. average annual precipitation :

  • Hot + very wet → tropical rainforest.
  • Hot + very dry → desert.
  • Moderate temp + moderate rain → temperate forest or grassland, depending on how much rain and how it’s distributed.

These long‑term averages and patterns (not just one weird year) limit which plants can dominate, and those plants define the biome.

2. Latitude and altitude (where you are on Earth)

Where a place sits on the globe strongly shapes its climate:

  • Latitude :
    • Near the equator (low latitudes) → more direct sunlight, generally warmer, often wetter → tropical biomes.
* Toward the poles (high latitudes) → less sunlight, colder → boreal forest, then tundra.
  • Altitude :
    • Climbing a mountain is like traveling toward the poles; temperature generally drops with height, so low‑elevation forest can give way to alpine meadows or tundra near the peaks.

Latitude affects sunlight, sunlight affects temperature and atmospheric circulation, and those affect rainfall patterns—so these factors indirectly decide which biome fits.

3. Rain shadows, oceans, and wind patterns

Two regions at the same latitude can have different biomes because of geography:

  • Mountains and rain shadows :
    • Moist air hits a mountain, rises, cools, and drops rain on the windward side (lush forest).
    • By the time air crosses to the leeward side, it’s dry, creating steppe or desert.
  • Distance from the ocean :
    • Coasts often have milder, wetter climates; interiors of continents can be more extreme (hotter summers, colder winters, often drier).
  • Ocean currents and wind belts :
    • Warm currents can make regions wetter and milder; cold currents can help create coastal deserts.

All of these modify the basic temperature‑and‑rainfall combo and can shift which biome appears in a given spot.

4. Soil and fire (fine‑tuning the biome)

Once climate sets the broad “biome zone,” other factors shape the exact type:

  • Soil :
    • Nutrient‑rich, deep soils can support dense forests; poor, thin, or salty soils may favor grasslands, scrub, or sparse woodland even in places that get enough rain for forest.
* Soil pH, texture, and drainage all influence which plants can dominate.
  • Fire :
    • In some climates, regular natural fires prevent forests from taking over and maintain grasslands or savannas.

These do not usually override climate at the global scale, but they help decide which version of a climate‑appropriate biome you get.

5. Living things themselves

Biomes are defined partly by what grows and lives there, and that life can feed back on the environment:

  • Dominant vegetation (trees vs. grasses vs. shrubs) is the practical marker we use to name biomes.
  • Plants influence shade, humidity, and soil; animals affect grazing and seed dispersal.

But these biological factors operate within boundaries set mostly by climate and soil.

Putting it all together (an example)

Imagine a region at mid‑latitudes:

  • If it is moderately warm with high rainfall year‑round → temperate rainforest or dense temperate forest.
  • Same temperature, but less rain and summer droughts → grasslands and open woodland.
  • Add a rain shadow that dramatically cuts precipitation → shrubland or desert.

The climate template stays central, but mountains, oceans, soils, and disturbance like fire refine which biome actually appears.

Bottom line:
The type of biome that can exist in a region is determined mainly by the long‑term pattern of temperature and precipitation, shaped by latitude, altitude, and global circulation, then fine‑tuned by factors like soil, topography, fire, and the dominant vegetation itself.

Information gathered from public forums or data available on the internet and portrayed here.