#Biomes-concept and classification.

Ecosystem Structures & Functions/Environmental Sciences.
#Biomes-concept and classification.

Objectives

• What are biomes

• An overview of some biome concepts

• The schemes of biome classification

• Concept of Biogeographic regions/realms

• Terrestrial Ecoregions of the World

• the Freshwater and Marine Ecoregions of the World

Introduction

Biomes are large geographical regions of earth which have characteristics types of biotic communities adapted to the climate of the region. The climate, geography, and soil of a region determine what type of biome can exist in that region, which are defined without reference to plant species composition (Moncrief et al., 2016). The biomes have developed over long periods of time, during which the distribution of land masses, ocean basins and climate zones have changed continually. Climate has a major regulatory effect on the evolution of flora and fauna, which in turn affect the characteristics type of vegetation with marked differences in growth form, leaf morphology and seasonality of foliage. Major biomes include deserts, forests, grasslands, and tundra, and several types of aquatic environments. There are different ways of classifying biomes but the common elements are climate, habitat, animal and plant adaptation, biodiversity and human activity. Each biome consists of many ecosystems whose communities have adapted to the small differences in climate and the environment inside the biome. While discussing various concerns with the biome concept, Moncrief et al. (2016) have stated that biomes are still useful organizing principles for describing the functioning of the world's ecosystems and the role of these ecosystems for Earth system function.

Biome Concepts

Alexander van Humboldt in his pioneering work on plant geography found a close relationship between climate and vegetation in geographically disjunct regions, exhibiting climatic similarity in similar regions (van Humboldt 1807). Alexander van Humboldt was a German explorer and naturalist, with his book Kosmos, he made a valuable contribution to the popularization of science. The biome concept as developed by Schimper (1903) is based on the idea that similar climates select for similar plant forms independent of differences in history. An overview of some biome concepts is briefly presented in Table 21.1 to give an idea of different ways of classifying biomes. In many early biome concepts, climate parameters were clearly incorporated into the definition of a biome (Table 21.1). Holdridge (1947) produced a systematic scheme of Life Zones describing large vegetation formations based on three climatic factors, i.e., bio-temperature, mean annual precipitation, and

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