No seasons, Temp is constant. High precipitation throughout the year. (>200 cm)

Between 10 °N and S.

High Biomass and diversity (50% of earths species)

Broadleaved Evergreen and Deciduous trees

Vertical Layers of forest to capture light

Nutrients house in plants rather than soil, reulsting in shallow root systems.

Disappearing at alarming rate due to logging and conversion to pasture and croplands. 

Rainfall in winter

Wet and Dry seasons associated with movements of ITCZ- Inner tropical convergence zone

From 10° to the tropics of capricon (23.5°S) and the Tropics of Cancer (23.5°N)

Shorter trees, deciduous in dry seasons, more grasses and shrubs

Tropical dry forests- rain shadows and wind direction so little rain

Thorn woodlands- trees have heavy thorns to protect from herbivores

Tropical savannas- grasses with intermixed trees and shrubs

Fires (and grazing), some fires are set by humans

In africa, large herds of herbivores also influence the balance of grass and trees

Associated with High pressure zones around 30° N and S. High temps, low water availability

Sparce vegetation and animal populations

Many plants exhibit stem succulence

Cactus= western

Euphorb= Eastern

They use it for agriculture and grazing, which means that they must irrigate the soil resulting in soil salinization. 

Long term droughts in association with unsustainable grazing can result in deserification which is loss of plant cover and soil erosion

Abundant- between 30° and 50° lat. 

Seasonal variation, warm moist summers and cold dry winters. 

Grasses dominate; maintained by frequent fires and large herivores such as bison

Grasses grow extensive roots to cope with dry conditions, results in accumulation of organic matter and high soil fertility. Most is converted to agriculture. 

in more arid grasslands, grazing by domesticated animals can exceed capacity for regrowth, leading to grassland degradation and desertification. 

Irrigation of some grassland soils has resulted in salinization

Wet season in winter, hot dry summers. 

Mediterranean type climates- West Coasts of the America's, Africa, Australia, and Europe. 

Vegetation is evergreen shrubs and trees

Fire is a common feature, so floara and fauna have adapted to withstand fires. 

Also called Chaparral in US

some have been converted to crops and vineyards, but the soils are nutrient poor

Urban development has reduced the biome in some areas, such as S CA. Increased fire frequency reduced the ability of the vegetation to recover, and invasive grasses can move in

Must have enough rainfall to support tree growth

Leaves are dropped during winter after sequestering nutrients. 

Oaks, maples, and beeches occur here

Soils are ferile and agriculture and silviculture has been a focus for centuries. Very little old growth temperate forest remains. 

Species shifts are due to mutrient depletion by agriculture and invasives such as the chestnut blight. 

Climate change may cause shift to savannas or prairie

In coastal and maritime zones

Lower diversity than tropical and deciduous forests. 

Leaves tend to be acidic, and soils nutrient poor

50-400 cm rain. Known as Temperate Rainforests. Southern pine Forests are recognized by most ecologists as a separate biome type 

They are used for wood and paper pulp, this this biome has been logged extensively (SPF Spruce, Pine and Fur)

Very little old growth temperate evergreen forest remains

In some areas, planting of non-native species and uniformly aged stands has resulted in very different ecological conditions 

The suppression of fires in western North America has increased the density of forest stands, which results in more intense fires when they do occur. 

It also increases the spread of insect pests and pathogens

Air pollution (acid rain especially) has damaged some temperate evergreen forests. 

Most precipitation is snow, animals are either migratory, subterranean, or very large. They have long severe winters. Soils are in a Permafrost state, so that impedes drainage and causes soils to be saturated. 

Lack earthworms, so organic matter accumulates. 

Trees are confiers- pines, spruces, fir, larches.

Perhaps the largest terrestrial biome

The cold wet conditions limit decomposition, so soils have high organic matter. 

In summer drought, forest fires can be set by lightning and nurn noth trees and soil. 

In low lying areas, extensive peat bogs form. 

They have NOT been greatly affected by human activity. 

However, logging and oil and gas development occur in some regions. These impacts will increase as energy demands increase. 

Climate warming may result in release of carbon stored in boareal soils, creating a positive feedback to warming. 

Mostly in Arctic, cold temps and low precipitation. 

Short summer with long days. 

Vegetation is sedges, forbs, grasses, low-growing shrubs, lichens, and mosses. 

Permafrost is widespread. 

Repeated freezing and thawing results in sorting of soil materials according to texture. 

Polygons of soil form at the surface, with upraised rims and depressed centers

settlements are sparse in the tundra, thus it contains some of the most pristine habitats on Earth. 

Animals include caribou, musk oxen, and many migratory birds (Snow Geese) 

Predators= wolves and brown bear