24.10.14 Land Biomes

• onshore moist air from the Pacific ocean hits the mountains near Seattle=rainy there
• onshore moist air from the lower Atlantic ocean hits the amazon basin=rainy there
• dry air moving down from the Mediterranean moves over the Sahara Desert=dry there

• The Big Island has 8 of the 9 biomes, or in the 12 biome model, we have 11/12, or 9 of 13, or 10 of 14 in another model.
  
• Many models...https://www.hawaiimagazine.com/content/hawaii-has-10-worlds-14-climate-zones-explorers-guide-each-them
• Traveling up a mountain is like crossing biomes. Check this out:
  

• Imagine driving from Hamakua or Hilo up to the summit of Mauna Kea: tropical rain forest to temperate (mild) rain forest to boreal (north) forest to tundra. 
• There is even a glacier up on Mauna Kea. Cool.
• This would be like starting in the upper right corner of the diagram and moving diagonally down and to the left.
  

Biomes provide the physical and climatic framework, while biodiversity fills that framework with living systems. Warmer and wetter biomes usually support greater biodiversity, while harsher biomes restrict it.

Biodiversity is complex (genes, species, ecosystems), ecologists usually talk in relative terms: how species richness compares across biomes. I’ll use the classic global biodiversity gradient (warm + wet = highest; cold + dry = lowest).

Relative Biodiversity by Biome

1 = very low diversity and 10 = very high diversity, based on species richness patterns.

Key Patterns

1. Latitude Gradient: Biodiversity increases from poles (tundra) → tropics (rainforest).

2. Precipitation Effect: Wetter biomes generally support more plant species → more niches for animals.

3. Seasonality vs. Stability: Seasonal environments (temperate/seasonal forests, savannas) have moderate-high diversity, but not as high as stable, year-round productive environments (rainforests).

4. Extremes Are Low: Very cold (tundra) and very dry (deserts) are biodiversity “deserts.”

• These diagrams are how climatologists describe biomes without a cool map. 
  
• The blue line is the amount of rainfall, with units on the RIGHT side of the graph. 
  
• The red line is the temperature, with units on the LEFT side of the graph. 
  
• The shaded region in the months below (jfmamjjasond) is the growing season when temperatures are above freezing. 
• When the precipitation line is above the temperature line, growth is limited by temperature (e.g. freezing). 
• When the blue line is below the red line, growth is limited by precipitation (e.g. the desert).
  
• Start with the north: Tundra is what you'd see in Alaska. 
• Permafrost is soon to be in the news. 
• It is made of permanently frozen ground a few feet below the surface. 
• Even roots cannot penetrate it, so some trees grow in a stunted fashion. 
• It is also composed of frozen organic matter, which when it melts will decompose, releasing CO2 and CH4 (methane), which is 20x as powerful as CO2 as a greenhouse gas.
  

• Note the short growing season. 
• Any plants that survive usually have an oily sap (pine trees, evergreens) that does not freeze. 
• Also note the serious cold in the winter-animals have to adapt to these (fur, hibernation, etc.)
  

• Temperate (mild) forests are nicer, longer growing season, and rarely freeze. 
  
• They are usually near the ocean, so they do not freeze (ocean is a huge heat sink). 
• They often have lots of rain (think of Seattle). 
• You may recall these are places where the surface parts of Ferrell and Polar cells converge, bringing in clouds and as these clouds rise into the atmosphere, they release their water as precipitation.
  

• Temperate (mild) seasonal forest actually has seasons
  
• Deciduous trees can live here, like maple and oak. It gets close to freezing, but no real dry season.
  

• Is like much of southern California, or the Mediterranean. 
  
• Wine can grow here. It is also known as the mediterranean (medi=middle, terra=earth) biome. 
  

• Is a dry, grassy area, like Oklahoma, although it does get very cold there, so think more of Texas, or the Gobi desert. 
• Again, growth is rain limited: (you may recall these are near Hadley/Ferrel cell subsidence, so dry air from space falls here). 
• These areas tend to be far from large bodies of water, so they have more extreme temperatures than similar latitudes near water (e.g. Italy, France, California)
  

• Is the rainiest of them all, and much of our island has this near the shore. 
• Warm temperatures, and paradoxically poor soil nutrition (all of the nutrients are in the plants). 
• On Mt. Waialeale on Kauai, the rainfall is 480 INCHES per year, 2.5 times as high as the high point on the chart below:
  

• Africa and Brazil hold the next biome: Savanna or tropical seasonal forest. 
• Think of Madagascar (the film): not many large trees, room for animals to roam, lots of grass, happy lions, maybe a bossy penguin or two...Growth dependent on rainfall: (blue line below red one)
  

• Finally, the subtropical desert biome, like what you'd see in the Sahara desert (another film), or most of Australia, the Atacama in Chile, the Mojave desert in California, and some of Mexico. 
• Note the Gobi desert is not on this list-too cold. Again, note these areas are where dry air subsides (falls) from the Hadley and Ferrell cells.
  

Major Human Impacts by Biome

Tundra: Oil & gas drilling, pipelines, mining scars; melting permafrost releases greenhouse gases.

Boreal Forest (Taiga): Logging, oil extraction, mining; climate change → fires & pest outbreaks.

Temperate Forest: Deforestation, urban expansion, pollution (acid rain), invasive species.

Seasonal Temperate Forest: Habitat fragmentation, overhunting, climate change alters cycles.

Woodland–Shrubland: Urbanization & wildfires, overgrazing, agriculture (vineyards/olive groves).

Temperate Grassland: Converted to cropland, overgrazing causes erosion, fire suppression alters

balance.

Tropical Rainforest: Deforestation for logging, cattle, palm oil; mining & roads reduce biodiversity.

Tropical Soils: Slash-and-burn, monocultures deplete nutrients, fertilizer runoff pollutes water.

Savanna: Poaching, overgrazing → desertification, fire suppression disrupts ecosystem.

Subtropical Desert: Off-road vehicle damage, urban sprawl, water depletion from irrigation.

Aquatic Biomes: Pollution (plastic, fertilizer), overfishing, dams alter rivers, ocean acidification.

Chesapeake Bay: Agricultural runoff → eutrophication, overfishing, sediment pollution, sea level rise.

Download Biomes_Study_Sheet_with_Human_Impacts.pdf (application/pdf, 4.5 KB)

Biome Game:

Download Find these biomes below:.pdf.pdf (application/pdf, 980.2 KB)