An Introduction to Ecology and the Biosphere Ecology

An Introduction to Ecology and the Biosphere

Ecology - the study of the interactions between organisms and their environment

Ecology - levels 1. Organismal ecology 2. Population ecology 3. Community ecology 4. Ecosystem ecology 5. Biosphere ecology

Biosphere Ecosystem Community Population Organism

The environment of any organism includes the following components: Abiotic factors: non-living factors Ex: temperature, light, water nutrients

Biotic Factors: effect of other organisms (living components) Ex: competition, predation, herbivores

Abiotic Factors 1. Temperature 6. Rocks and Soil 2. Water 7. Disturbance 3. Salinity 4. Sunlight 5. Wind

Temperature • affects biological processes Cold – cells will rupture if they expand while freezing Hot – many proteins denature above 45 o. C

• life can only exist over a fairly narrow temperature range

Water • cells must maintain a correct water potential (keep from exploding or drying out)

Salinity Salt concentration of water in the environment affects the water balance of organisms through osmosis • most aquatic organisms are restricted to either freshwater or saltwater habitats by their limited ability to osmoregulate

• many terrestrial organisms can excrete excess salts from specialized glands or in feces • Salt flats and other high-salinity habitats typically have few species of plants and animals

Sunlight • provides energy for photosynthesis, which drives most food webs • plants often compete for light because of shading or absorption of light by deep columns of water

• also important to the development and behavior of organisms that are sensitive to photoperiod – relative lengths of daytime and nighttime

Wind • affects temperature (wind-chill factor) • contributes to water loss by increasing the rate of evaporation for many organisms (both plant and animal)

Rocks and Soil • physical structure, p. H, mineral composition of rocks and soil limit where plants can grow • plants limit what animals can be found in an area

Disturbance • disturbance is often an important part of an environment • allows organisms to re-colonize an area Ex: fire humans wind

Climate Four abiotic factors are the major components of climate temperature precipitation sunlight wind

• climate shapes environments and what organisms can live in a particular area • particularly temperature and water availability • climate patterns can be described on two scales: macroclimate and microclimate

Macroclimate – patterns on the global, regional, and local level Microclimate – very fine patterns, such as those encountered by the community of organisms that live beneath a fallen log

Global Climatic Factors • Solar Radiation and Latitude • Axis Tilt/Seasons • Air/Water Circulation Patterns

Solar Radiation and Latitude • changes the amount of light and energy delivered per surface area

Result • poles: less light • equator: more light • the unequal heating causes air and water to circulate

Seasonality • caused by the Earth's tilt • day length changes over time • many organisms are restricted in range by how well they adapt to changing seasons

Global Air Patterns • air rises when heated, sinks when cools • zones of rising/sinking are created • Earth's rotation causes zones to "twist”

Result • air circulation patterns • rainfall patterns rising air: wet areas descending air: dry areas

Mountains affect the amount of sunlight reaching an area and consequently the local temperature and rainfall

• south-facing slopes in the Northern Hemisphere receive more sunlight than nearby north-facing slopes and are therefore warmer and drier • these abiotic differences influence species distribution

Altitude and Latitude • mirror each other their biomes are similar because the environments are similar Ex: Alpine = Tundra

When warm, moist air approaches a mountain, the air rises and cools, releasing moisture on the windward side of the peak

On the leeward side, cooler, dry air descends, absorbing moisture and producing a “rain shadow’ effect • deserts commonly occur on the leeward side of mountain ranges examples: Mojave Desert of North America, Gobi Desert of Asia