Biomes & Ecosystems

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Key questions

• What defines a biome and an ecosystem?

• How can humans have an impact on ecosystems? How can this be measured?

• What threats exist to forest ecosystems?

Definition: Biome

Biome:a region which has distinct types of organisms, substrates, and climate, all interacting to produce a large, distinct, and complex biotic community. a major biotic community characterized by the dominant forms of plant Life and the prevailing climate. The classification of certain physical and chemical characteristics of an environment, such as tundra, grassland etc.

Definition: Ecosystem• ecosystem :An ecosystem is the dynamic and

interrelating complex of plant and animal communities and their associated non-living environment.

• The physical and climactic features and all the living and dead organisms in an area that are interrelated in the transfer of energy and material.

• An interacting complex of a community and its environment functioning as an ecological unit in nature. differs from system in being a more rigorous definition that encompasses and requires assumptions of energetics, ecological interactions, species adaptations and so forth. a system formed by the interaction of a community of organisms with their physical environment. Description of an area with its biotic and abiotic factors is similar, such as grassland, woodland etc.

Importance of ecosystemsVital services

Climate regeneration

Air purification

Water control

Flood protection

Water purification

Cycling of nutrients

Generation of humus

Maintain biodiversity and gene pool

Wildlife habitats

Employment and recreation

To understand the nature of the earth's major biomes, one needs to learn for each:

• The global distribution pattern: Where each biome is found and how each varies geographically. A given biome may be composed of different taxa on different continents. Continent-specific associations of species within a given biome are known as formations and often are known by different local names. For example,the temperate grassland biome is variously called prairie, steppe, pampa, or veld, depending on where it occurs (North America, Eurasia, South America, and southern Africa, respectively).

• The general characteristics of the regional climate and the limitations or requirements imposed upon life by specific temperature and/or precipitation patterns.

• Aspects of the physical environment that may exert a stronger influence than climate in determining common plant growthforms and/or subclimax vegetation. Usually these factors are conditions of the substrate (e.g., waterlogged; excessively droughty, nutrient-poor) or of disturbance (e.g., periodic flooding or burning).

• The soil order(s) that characterize the biome and those processes involved in soil development.

• The dominant, characteristic, and unique growthforms; vertical stratification; leaf shape, size, and habit; and special adaptations of the vegetation. Examples of the last are peculiar life histories or reproductive strategies, dispersal mechanisms, root structure, and so forth.

• The types of animals (especially vertebrates) characteristic of the biome and their typical morphological, physiological, and/or behavioral adaptations to the environment

World Biomes

• We study forest biomes only!

Forests today

• Present-day forest biomes, biological communities that are dominated by trees and other woody vegetation can be classified according to numerous characteristics, with seasonality being the most widely used. Distinct forest types also occur within each of these broad groups.There are three major types of forests, classed according to latitude:

• tropical • temperate • boreal forests (taiga)

Taiga

Tropical Rainforest

Temperate Broadleaf Deciduous Forest (+ temperate

rainforest)

Compare & contrast different types of forest in terms of

mean NPP and mean biomass