Chapter 6 Communities, Formations, and Biomes
Dec 16, 2015
Mediterranean Biome• Winter wet, summer dry• Warm summers, mild winters• Found in conjunction with cold ocean currents• Valley forest, open woodlands, shrublands,
grasslands• California – chaparral – oak (Quercus spp)• Chile – matorral – Northfagus obliqua and
Acacia• South Africa – fynbos• Australia - eucalyptus• Europe – maquis – Pines (Pinus spp), Cedars
(Cedrus spp), Fir (Abies spp)
• Vegetation dependent on long summer drought, fire, and low soil nutrients
• Annuals more common than perennials • Drought strategies (avoiders)
– Black sage (Salvia mellifera) loses all but outer leaves in summer
– Shrubs – dimorphism– California valley oak (Quercus lobata) – deep
tap roots– Low soil nutrients makes deciduousness
impractical
Mediterranean Biome
• Fire-tolerant species
• Scarification, serotinous cones, thick bark, resprouting
• Invasives from Australia: melaleuca, eucalyptus
Mediterranean Biome
Temperate Grassland
• North America – prairie
• South America – pampas
• Eurasia – steppe
• South Africa – grassveld
• Variable temperature and rainfall
• Fertile soils
• 20% herbs, 80% grasses on grasslands
• Trees along waterways
• Shortgrass – arid regions– Shallow, extensive root system– 1 foot tall
• Tallgrass – wetter regions– Deep roots to access water table– 6 feet tall– 1% remains
• Fires common• Invasive annual grasses
Temperate Grassland
Temperate Forest
• Variable temperatures and rainfall
• In the Southern Hemisphere, evergreens
• In the Northern Hemisphere, deciduous
• General structure: canopy, subcanopy, herb layer
• Biodiversity dependent upon glacial history
• Deciduous forest increasing as farms abandoned – second-growth forest
Temperate Rainforest
• High rainfall, mild temperatures, close to oceans
• Moisture from fog and orographic lifting
• Large, long-lived, evergreen trees
• Redwoods, Douglas fir
• Lower diversity than temperate deciduous forest and tropical rainforest
Coniferous Boreal and Montane Forest
• Northern Hemisphere• Pine, Spruce (Picea spp.), and Fir in North
America and Europe• Bristlecone pine (Pinus aristata)• Larch (Larix spp) in Asia• Krummholtz – high elevation shrublands• Little understory growth• Fire-tolerant plants
Tundra Biome
• Found beyond treeline in the Arctic (Arctic Tundra) and in high mountians (alpine tundra)
• Variable temperatures and rainfall
• Lower elevations and latitudes: willow (Salix spp.), shrub birch (Betula nana), alder (Alnus spp.), sedges, grasses, herbs, and mosses – low arctic tundra
Tundra Biome• High arctic tundra (polar desert) – higher
elevations and latitudes – arctic willow (Salix arctica) and heliotropic flowering plants
• Perennials
• Low biodiversity and biomass
• With the exception of crowberry (Empetrum nigrum), arctic and southern hemisphere alpine tundra have no similar species