2 Biomes
This chapter provides a brief overview of the main ecological divisions in the world
and will supply a background of natural history for the chapters that follow.
The earth, or biosphere, can for convenience be divided up into major regions. On
land these regions are characterized by a similarity of geography, landform, and major
floral and faunal groupings. Thus, we can talk about the tundra – high latitude, cold,
usually flat or rolling relief, and with low-growing shrubs like willows and mat-
forming herbs. Tropical lowland forest is very different – moist, warm regions near
the equator dominated by dense forest. Regions with similar characteristics are called
biomes. They are divided further into units of greater similarity, called ecosystems,
based on environment and groupings of plants and animals. Ecosystems are the main
functional units of the biosphere, largely self-contained apart from inputs of energy
and nutrients from outside. Some organisms, such as migrants and dispersers, can
move between ecosystems. They vary in size from parts of oceans to small water-
sheds on land.
Ecosystems comprise the abiotic environment and the biotic groupings of plant
and animal species called communities. Each of the species in a community has a
characteristic density (or range of densities) and it is the interaction of these vari-
ous populations that gives a particular community its special features. Populations
have their own features, for example age and sex ratios, and these are affected by
both the environment in which the animals live and the particular adaptations of
the individuals, their morphology, physiology, and behavior. Thus, in the study of
wildlife ecology and management we need to understand both the large-scale spatial
and temporal events occurring in biomes and ecosystems, and the smaller-scale
characteristics of individuals and populations.
Habitat is the suite of resources (food, shelter) and environmental conditions
(abiotic variables such as temperature and biotic variables such as competitors and
predators) that determine the presence, survival, and reproduction of a population.
In Chapters 5, 8, and 12 we shall examine the relationships between populations and
their resources. In Chapters 8, 9, and 10 we examine how some components of their
habitat, such as competitors and predators, impinge on the populations and their role
in wildlife management.
We will now review the main features of the various biomes and some of the wildlife
forms that inhabit them. Although biomes are characterized by many different prop-
erties, they can be summarized conveniently according to mean annual temperature
and rainfall (Fig. 2.1). Biomes are groupings of ecosystems with similar environment
and vegetation structure (physiognomy). There are six major terrestrial biomes
distinguished by their physiognomic characteristics: forests, woodlands, shrublands,
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2.1 Introduction
