CAMPBELL & REECECHAPTER 52

An Introduction to Ecology&

the Biosphere

Ecology

from Greek, oikos = homescientific study of interactions between

organisms & environment

Scope of Ecological ResearchOrganismal Ecology: concerned with individual’s

structure, physiology, behavior & its challenges posed by its environment

Population Ecology:analyzes factors that affect population size; how & why it changes over time

Community Ecology: interactions between species: how predation, competition affect community structure

Ecosystem Ecology: nrg flow & biochemical cycling between organisms & their environment; abiotic factors included

Landscape Ecology: factors controlling exchanges of nrg, materials & organisms across multiple rcosystems

Global Ecology: how regional exchange of nrg & materials influences functioning & distribution of organisms across the biosphere

Climate

long-term, prevailing weather conditions in given area

*most significant influence on the distribution of organisms on land & in oceans

4 Components of Climate

1. Temperature2. Precipitation3. Sunlight4. Wind

Global Climate Patterns

determined mostly by 1. input of solar nrg

establishes temp variations cycles of air & water movement evaporation of water dramatic latitudinal

variations in climate2. Earth’s movement in space

Latitudinal Variation in Sunlight Intensity

Earth’s curved shape causes latitudinal variation in intensity of sunlight.

because sunlight hits Tropics (23.5° N and 23.5° S latitude) most directly, more heat & light /unit surface area are delivered there

@ higher latitudes sunlight strikes Earth @ oblique angle so light nrg more diffuse on Earth’s surface

Global Air Circulation & Precipitation Patterns

intense solar radiation @ equator initiates global pattern of air circulation & precipitation

hi temps evaporate water warm, wet air rises flow toward the poles

air cools precipitation dry air masses descend @ ~ 30° latitude (N & S)

@~60° latitudes air rises cool precipitation to poles

Global Air Currents

Wind Patterns

air flowing close to surface creates predictable global wind patterns

as Earth rotates land near equator moves faster than that @ poles, deflecting the winds from staying on vertical path

cooling trade winds blow east west in the tropics

prevailing westerlies blow from west east in temperate zones

Global Wind Patterns

Climate

Macroclimate: patterns on the global, regional, & landscape level

Microclimate: very fine localized patterns

Climate patterns can be modified by: seasonal variations in climate large bodies of water mountain ranges

Seasonality

Earth’s tilted axis of rotation & revolution around Sun every year cause strong seasonal cycles in mid to hi latitudes

Bodies of Water

because of hi specific heat of water, oceans & large lakes tend to moderate the climate of nearby land

hot day: land warmer than water air over land warms & rises draws cooler air from over water to land

@ night: land cools faster than water air over now warmer water rises draws cooler air over land back over water

Lake-Effect Snow

Global Circulation of Surface Water

Mountains

Microclimate

every environment on Earth is characterizes by small-scale differences in abiotic factors chemical & physical attributes: temperature, amt of shade, light, water &

nutrients, fallen tree used as shelter

Global Climate Change

increasing greenhouse gas concentrations in the air are warming Earth & altering the distributions of many species some will thrive others will not be able to shift their ranges

quickly enough to reach suitable habitat

Biomes

major life zones characterized by vegetation type (in terrestrial biomes) or by the physical environment (in aquatic biomes)

Climograph

plot of annual mean temperature & precipitation in a particular region

Climograph for Some Major Biomes

Climographs

show that temp & precipitation are correlated with biomes

because other factors also play a role in biome location: biomes can overlap

General Features of Terrestrial Biomes

most named for major physical or climatic features & for their predominant vegetation

each biome also characterized by:microorganismsfungianimalsall adapted to that particular environment

Ecotone

area of integration: where biomes overlap

Terrestrial Biomes

layering w/in biome due to shapes & sizes of plants

flora dependent on annual precipitation & temps

Biome Species Composition

varies w/in each biome ex: eastern part of one large lake may have

different water bird than western portion

Disturbance

event that changes a community: removes organisms from it & alters the resource availability ex: forest fire

Tropical Forest

Distribution: equatorial & subequatorialPrecipitation:

Tropical Rainforest: constant, 200 -400 cm/yr

Tropical Dry Forest: seasonal, 150 – 200 cm/yr

Temperature: high all yr, average 25 – 29°C , little

seasonal variation

Tropical Forest

Tropical Forest: Plants

vertically layeredintense competition for light

Tropical Forest Plants

Tropical Rainforest see all layers,

some with 2 layers of subcanopy trees

broadleaf evergreen trees dominate

epiphytes (air plants) & orchids typically cover trees

Tropical Dry Forest see fewer layers drop leaves during

dry season commonly have

thorny shrubs & succulent plants

Tropical Forest: Animals

millions of species5 – 30 million undiscovered species of

insects, spiders, other arthropodshighest animal diversity than anywhere else

on Earthall adapted to vertically layered environment

Tropical Forest: Human Impact

thriving communities of man have lived in tropical forests for hundreds of years

overpopulation leading to agriculture & development are destroying many tropical forests

DESERT

Distribution: occur in bands near 30° N & S latitude or in

interior of continentsPrecipitation:

low & variable; <30 cm/yrTemperature :

variable seasonally & daily hot desert: max T may > 50°C dry desert: low T may < -30°C

World Distribution of Deserts

Deserts

Desert Plants

see low, widely scattered vegetation see more bare ground than other terrestrial

biomessucculents

cacti euphorbs

deeply rooted shrubs & herbs grow during brief rainy periods

Desert Plants

Adaptations: heat & desiccation tolerance water storage reduced leaf surface area CAM photosynthesis physical defenses:

spines chemical defenses:

toxins in leaves of shrubs

Desert Animals

Common animals:SnakesLizardsScorpionsAntsBeetlesBirds: migratory & residentseed-eating Rodents

Desert Animal Adaptations

many species are nocturnalwater conserved in variety of ways:

only water some get is by metabolizing carbohydrates water + carbon dioxide

Desert: Human Impact

use of long distance transport of water & deep groundwater wells have allowed large populations of man to make the desert their home

end result decreased diversity of some deserts

SAVANNA

Distribution: equatorial & subequatorial

Precipitation: seasonal rainfall 30 – 50 cm/yr dry season can last 8 – 9 months

Temperature : warm year-round: 24 – 29 °C more seasonal variation than tropical forests

Savanna Distribution

Savanna

Savanna Plants

scattered, variable density of treesmost plants have small leaves (adaptation to

dry conditions)Fires common in dry season: most dominant

plant species are fire-adapted & drought-tolerant

grasses & forbes (clover, wildflowers) tolerant of large grazing herbivores

Savanna Animals

dominant herbivores are insects especially termites

large herbivores migrate toward thicker vegetation & watering holes during dry season

Savanna: Human Impact

earliest humans lived in the savannaagriculture & hunting (poaching) have

reduced #s of large mammals

Chaparral

also called mattoral (Spain & Chile) garigue & maquis (southern France) fynbos (South Africa)

Chaparral

Distribution: midlatitude coastal regions

Precipitation: highly seasonal (rainy winters, dry summers) averages 30 – 50 cm/yr

Temperature : fall, winter, spring are cool (10 – 12°C) summer can get > 40°C

Chaparral Distribution

Chaparral

Chaparral Plants

dominated by shrubs, small trees, variety of grasses & herbs

plant diversity high though some species found only in very limited areas

adaptations to: drought: tough evergreen leaves fire:

herb seeds only germinate after hot fire roots are fire resistant (plants re-sprout quickly)

Chaparral Animals

natives include: browsers (deer,

goats) high diversity of

small mammals many amphibians,

birds, reptiles, insects

Chaparral: Human Impact

due to increased agricultural use of land chaparral areas have been heavily settled & reduced

man contributes to fires

Temperate Grassland

also called:veldts (South Africa)puszta (Hungary)pampas (Argentina & Uruguay)steppes (Russia)plains & prairies (North America)

Temperate Grasslands

Temperate Grassland

Precipitation: highly seasonal: dry winters/wet summers averages vary between 30 – 100 cm/yr periodic drought is common

Temperature : winters cold (< -10°C) summers moderately hot ( 30°C)

Temperate Grasslands

Temperate Grasslands: Plants

dominant plants are grasses & forbs some grasses 2 m high

many adapted to survive periodic drought & fires

grazing by herbivores helps prevent establishment of woody plants

Temperate Grasslands: Animals

native mammals large: bison, wild horses small burrowers: prairie dogs

Temperate Grasslands: Human Impact

most grasslands of North America & Eurasia converted to farmland

in other grasslands grazers have turned the grasslands deserts

desertification: Patagonia, Argentina

Northern Coniferous Forest

aka: taigaDistribution:

broad band across northern North America & Eurasia to edge of arctic tundra

Precipitation: 30 – 70 cm/yr periodic droughts are common

Temperature : winters cold (-50°C in Siberia) summers usually >20°C

Northern Coniferous Forest

Northern Coniferous Forest: Plants

dominated by cone-bearing trees pine, spruce, fir, hemlock some require fire to regenerate shape of conifers prevents too much snow

accumulating…so branches don’t break needle-or scale-like leaves reduce water loss

lower diversity of shrubs & herbs than in temperate broadleaf biomes

Northern Coniferous Forest: Plants

Northern Coniferous Forest: Animals

Birds: residents & summer migrantsinsects occasionally kill large tracts of treesMammals:

Moose Brown Bear Siberian Tiger

Northern Coniferous Forest: Human Impact

logging increasing at alarming ratenot many old stands remain

Temperate Broadleaf Forest

Distribution mainly in midlatitudes of northern

hemisphere smaller areas in Chile, South Africa,

Australia, New Zealand

Temperate Broadleaf Forest

Precipitation: 70 to > 200 cm/yr (includes snow) all seasons have precipitation

Temperature : winter averages ~ 0°C summers hot & humid/ up to 35°C

Temperate Broadleaf Forest

Temperate Broadleaf Forest: Plants

mature forest has distinct vertical layers including a closed canopy

dominant plants in North America are deciduous trees adaptation: drop leaves as weather gets

colder: uptake of water by roots not feasible when soil frozen

dominant plant in Australia: Eucalyptus

Temperate Broadleaf Forest: Animals

mammals, birds, insects make use of vertical layers

many mammals hibernate in wintermany birds (and some butterflies) migrate

south

Temperate Broadleaf Forest: Human Impactvirtually all original deciduous forests in

North America have been destroyed by urban development or logging…but have great capacity for recovery: some areas are returning over much of their original range

Tundra

Distribution: covers arctic: 20% Earth’s land surface tops of high mountains

Precipitation: 20 – 60 cm/yr in arctic tundra >100 cm/yr alpine tundra

Temperature: winter averages < -30°C summer averages < 10°C

Tundra

Tundra

Tundra: Plants

mostly herbaceous: mosses, grasses,

forbs + dwarf shrubs & trees, lichens

permafrost (frozen ground year round) prohibits growth of plant roots

Tundra: Animals

Birds: migratory, arriving for nesting in summer

Mammals: Residents: musk ox Migrators: caribou, reindeer

Predators: bears, wolves, foxes

Tundra: Human Impact

sparsely populated but has been greatly impacted by mineral & oil extraction

Aquatic Biomes

charaterized primarily by their physical environment rather than be climate

often layered with regard to light penetration temperature community structure

Zonation in Aquatic Biomes

light absorbed by water itself + photosynthetic organisms so…light intensity decreases rapidly with depth

Photic Zone: sufficient light for photosynthesis

Aphotic Zone: little light penetrates

Pelagic Zone = photic zone + aphotic zone

Zonation in Aquatic Biomes

Abyssal Zone: 2,000 – 6,000 m deep

Benthic Zone: the bottom of all aquatic biomes, shallow or

deepBenthos:

communities of organisms that live in sand & sediments of the benthic zone

More Definitions

Detritus: dead organic material that “rains” down

from photic zone; food source for benthosThermocline:

narrow layer of water where there is an abrupt temperature change

separates the more uniformly warm upper layer from the uniformly cold deeper water

many temperate lakes undergo a semiannual mixing of their water

Lakes

lake environment generally classified on basis of 3 physical criteria:

1. light penetration photic / aphotic

2. distance from shore / depth of water littoral / limnetic

3. open water / bottom pelagic / benthic

Marine Zonation

classified by 3 criteria:1. light penetration

photic / aphotic2. distance from shore / depth of water

intertidal / neritic / oceanic3. open water / bottom

pelagic / benthic / abyssal

Lakes

standing bodies of water range from ponds a few square meters in area to lakes covering thousands of square kilometers

Lake: Chemical Environment

lakes differ greatly in their salinity, O2 concentration, & nutrient content

Oligotrophic Lakes: nutrient poor O2 rich low in amt of decomposable matter

Eutrophic Lakes: nutrient rich O2 poor in deepest zones in summer high amt decomposable matter

Lakes: Geologic Features

oligotrophic lakes can become more eutrophic over time as runoff adds sediments & nutrients

oligotrophic lakes tend to have less surface area relative to their depth

Lakes: Oligotrophic

Lakes: Eutrophic

Lakes: Photosynthetic Organisms

Littoral Zone: shallow, well-lit waters close to shore rooted & floating aquatic plants

Limnetic Zone: waters too deep to support rooted plants phytoplankton, including cyanobacteria

Phytoplankton

Lakes: Heterotrophs

Limnetic Zone: small, drifting heterotrophs or zooplankton

(graze on phytoplankton)Benthic Zone:

assorted invertebrates (species depends on O2 content)

Fishes live in all zones that have sufficient O2

Zooplankton

Lakes: Human Impact

Runoff from fertilized land & dumping wastes water nutrient enrichment algal blooms O2 depletion fish kills

Wetlands

habitat that is inundated by water (at least part of the year) & supports plants adapted to water-saturated soil

due to high organic production by plants & decomposition by microbes: water & soil of wetlands periodically low in dissolved O2

*high filter capacity: both nutrients & pollutants

Wetlands: Geologic Features

Basin Wetlands: develop in shallow basins range: upland depressions filled in lakes

Riverine Wetlands: along shallow & periodically flooded banks of

streamsFringe Wetlands:

along coasts of large lakes & seas water flows back/forth due to changing water

levels or tides fresh water & marine biomes

Basin Wetlands

Riverine Wetlands

Fringe Wetlands

Wetlands: Autotrophs

among most productive biomes in worldwater-saturated soils great for plants

Lily pads Cattails Sedges Tamaracks Black spruce

Wetlands: Heterotrophs

diverse community of invertebrates, birds, reptiles, amphibians, and mammals

Herbevores: crustaceans aquatic insect larvae muskrats

Carnivores: dragonflies frogs alligators herons

Wetlands: Human Impact

draining & filling have destroyed up to 90% of wetlands

Streams: Physical Environment

most prominent characteristic: their currentstratified into vertical zones

Streams: Physical Environment

Headwaters: generally cold, clear turbulent, & swift

Downstream: generally warmer more turbid

Streams: Chemical Environment

salt & nutrient concentrations increase as get further from headwaters

Headwaters: generally rich in O2Downstream: + O2 unless has organic

enrichment

Streams: Geologic Features

headwaters: often narrow with

rocky bottomalternate between

shallow sections & deeper pools

downstream:wide stretchesmeanderingsilty bottoms

Streams: Photosynthetic Organisms

rivers that flow thru grasslands or deserts have phytoplankton or rooted aquatic plants

Streams: Heterotrophs

great diversity of fishes & invertebrates inhabit unpolluted streams

distributed in vertical zones organic matter from terrestrial vegetation is

primary source of food for aquatic consumers

Streams: Human Impact

pollutants from municipal, agricultural, & industrial sources kill aquatic organisms

damming & flood control impair natural functioning of stream ecosystems & threaten migratory species (salmon)

Estuary

a transitional area between river & seawhen high tide: salt water flows up estuary

channelhigher density sea water stays below lesser

density freshwater

Estuary: Chemical Environment

salinity varies from that of freshwater sea water & with rise & fall of tides

nutrients from rivers make estuaries some of most productive biomes

Estuary: Geologic Features

complex network of tidal channels, islands, natural levees, & mudflats

Estuary: Photosynthetic Organisms

saltmarsh grasses & algae (including phytoplankton) are major producers

Estuary: Heterotrophs

abundant #’s of worms, oysters, crabs, & many fish

many invertebrates & fishes use estuaries as breeding grounds

crucial feeding grounds for birds & some marine mammals

Estuary: Human Impact

Filling, dredging, & pollution have disrupted estuaries worldwide

Intertidal Zones

are periodically submerged & exposed by the tides, 2x daily on most marine shores

upper zones exposed to air for longer periods greater variation in temp & salinity

changes in physical conditions from upper to lower zones limits the distribution of many organisms to particular strata

Intertidal Zones: Chemical Environment

O2 & nutrient levels generally high & renewed with each turn of the tides

Intertidal Zone: Photosynthetic Organisms

high diversity & biomass of attached marine algae inhabit rocky intertidal zones

much lower diversity & biomass in sandy intertidal zones with vigorous wave action

sandy intertidal zones in protected bays or lagoons have rich beds of grass & algae

Intertidal Zone: Heterotrophs

animals here have multiple structural adaptations

rocky areas: ways to attach to hard surfaces sandy areas: many bury themselves feed on what tides bring them

Intertidal Zones: Human Impact

oil spill have disrupted ecosystem of many intertidal zones

construction of rock walls, barriers to reduce damage from erosion, storm surges also disrupts these zones

Ocean Pelagic Zone

open blue watersmixed constantly by wind & ocean currentsphotic zone extends deeper here (water is

clearer)

Oceanic Pelagic Zone: Chemical Environment

O2 levels generally highnutrient levels generally lower than in coastal

waterstropical oceans: thermally stratified all yeartemperate & hi-latitude oceans have spring &

fall turnover so generally nutrients renewed in photic zone

Oceanic Pelagic Zone: Geologic Features

covers ~70% Earth’s surfaceaverage depth = 4,000 mdeepest point: 10,000 m

Pelagic Zone: Photosynthetic Organisms

phytoplankton (including photosynthetic bacteria) dominate

due to vast area this zone covers: ~50% of all photosynthesis on Earth by them

Pelagic Zone: Heterotrophs

zooplankton most abundant group in this zone

graze on phytoplanktonincludes:

protists worms copepods shrimp-like krill jellies small larvae of invertebrates

Pelagic Zone: Heterotrophs

also include free-swimming animals: large squid fishes sea turtles marine mammals

Pelagic Zone: Human Impact

overfishing has depleted fish stocks in all oceans

all also polluted

Coral Reefs

formed largely from the calcium carbonate skeletons of corals

in photic zone of relatively stable tropical marine environments with high water clarity

sensitive to temps < 18 – 20° & > 30°Cfound in deep seas 200 -1,500 m deep

as much diversity as shallow reef

Deep Sea Coral Reef

Shallow Coral Reef

Coral Reef: Chemical Environment

require high O2 levels

Coral Reef Geologic Features

Corals require a solid substrate for attachment

typically: begins as fringing reef on young, high island forming an off-shore barrier reef as island ages coral atoll

Barrier Reef

Coral Atoll

Coral Reefs: Photosynthetic Organisms

unicellular algae live w/in tissues of corals in mutualistic relationship: provides corals with organic molecules

diverse multicellular red & green algae growing on reef also photosynthesize

Coral Reef: Heterotrophs

dominant heterotroph: corals are a diverse group of cnidarians

also high diversity of fishes & invertebrates

overall nearly as diverse as tropical rainforest

Coral Reef: Human Impact

populations of corals & fishes on decline due to humans collecting corals & overfishing

Global warming & pollution coral death

Marine Benthic Zone

consists of the seafloor under surface waters of the coastal (neritic) zone * the offshore (pelagic) zone

Benthic Zone

near-coastal areas only part to receive sunlight

water temp declines with depth while pressure increases

organisms in very deep abyssal zone adapted to cold (~3°C) & high water pressure

Benthic Zone: Chemical Environment

O2 levels usually high enough to support divers animal life

Benthic Zone: Geologic Features

most covered by soft sedimentsalso: rocky surfaces, submarine mts, new

oceanic crust

Benthic Zone: Autotrophs

shallow areas: seaweeds & filamentous algaedeep-sea hydrothermal vents:

on mid-ocean ridges chemo-autotrophic prokaryotes obtain nrg by

oxidizing H2 S formed by a reaction between hot water & dissolved sulfate (SO4 )

Benthic Zone: Heterotrophs

numerous invertebrates & fishesbeyond photic zone most animals rely on

organic material raining down from abovemany around hydrothermal ventsGiant tube worms: eat chemo-autotrophic

prokaryotes that live as symbionts w/in their bodies

Benthic Zone: Human Impact

overfishing has decimated some benthic fish populations (cod)

dumping of organic wastes has created oxygen-deprived benthic areas

Distribution of Species

are a consequence of both ecological & evolutionary interactions thru time

Ecological Time differential survival & reproduction of

individuals that lead to evolutionEvolutionary Time

thru natural selection, organisms adapt to their environments over time frame of many generations

Global & Regional Patterns

ecologists ask not only where a species lives but also why it lives there

to answer these ?s focus on both biotic & abiotic factors that influence distribution & abundance of organisms

Flowchart of Factors Limiting Geographic Distribution

Dispersal

movement of individuals or gametes from their areas of origin or from centers of high population density

dispersal of organisms is critical to understanding the role of geographic isolation in evolution

Natural Range Expansion

long distance dispersal can lead to adaptive radiation: the rapid evolution of ancestral species into new species that fill many ecological niches

Species Transplants

by observing the results of intentional or accidental transplants of species to areas where it was previously absent, ecologists may determine if dispersal is a key factor limiting distribution of a species

species introduced to new geographic locations often disrupt the communities & ecosystems to which they have been introduced & usually spread beyond area of introduction

Behavior & Habitat Selection

habitat selection one of least understood processes

Insect: some females will only lay eggs near plant that species most prefers thus limiting habitat

Biotic Factors

If behavior does not limit distribution of species then do other species influence it?

Often (-) interactions with predators or herbivores restricts ability of a species to survive & reproduce

Biotic Factors

besides presence or absence of predators or herbivores presence or absence of pollinators, food resources, parasites, pathogens, & competing organisms can act as biotic limitations on distribution of a species

Abiotic Factors

temperature, climate, water, oxygen, salinity, sunlight, soil can all limit a species distribution

most areas have fluctuations in nearly all these abiotic factors

some organisms can avoid some of the more extreme annual fluctuations

dormancy storage of food or water supplies

Temperature

important abiotic factor in distribution of organisms because of its effect on biological processes

cells would rupture if water in them freezes when 0°C

proteins of most organisms would denature if temp > 45°C

extraordinary adaptations allow some species to survive in temp ranges other organisms cannot survive in

Colors of Pool due to Thermophiles

Water & Oxygen

terrestrial organisms face nearly a constant threat of dehydration: their distribution reflects their ability to obtain & conserve water

water affects oxygen availability in aquatic environments & in flooded soils

surface waters of streams tend to be well oxygenated due to rapid exchange with atmosphere

Salinity

affects water balance of organisms thru osmosis

most organisms can excrete excess salts by specialized glands or in feces & urine

salt flats or other high-salinity habitats have few species of plants or animals

Salmon go from freshwater salt-water & back have both behavioral & physiological mechanisms to osmoregulate

they adjust amt water they drink to balance their salt content

gills switch from taking up salt in freshwater to excreting salt in sea-water

Sunlight

in aquatic environments, every meter of water depth absorbs 45% of red light & ~2% of blue light passing thru it

Sunlight

too much increases temps as in deserts which stresses plants & animals

@ high elevations sunlight more likely to damage DNA & proteins because atmosphere is thinner so get more UV radiation

this damage + other abiotic factors reason why there is a tree line on mountain slopes

Rocks & Soil

pH, mineral composition, physical structure of rocks & soil limit distribution of plants & therefore animals that feed on them

pH can act directly thru extreme acidic or basic conditions or indirectly by affecting the solubility of nutrients & toxins

composition of riverbeds can influence water chemistry influences organisms that can live there