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Title Page Photo

““In short, the animal and vegetable lines, In short, the animal and vegetable lines, diverging widely above, join below in a loop.diverging widely above, join below in a loop.””

——AsaAsa Gray (Brainyquote.com)Gray (Brainyquote.com)

Ecosystems and Biomes• Two organizing principles

are ecosystem and biome.• Ecosystem: A Concept for

All Scales– Ecosystem —the totality of

interactions among organisms and the environment in the area of consideration.

• Encompasses both the living and nonliving portion and how energy flows among them.

• Weakness—there is an almost infinite variety in the magnitude of ecosystems that can be studied:

– Range includes whole Earth itself to drop of water.

Ecosystems and Biomes

• Biome: A Scale for All Biogeographers– Biome—a large,

recognizable assemblage of plants and animals in functional interaction with its environment.

– Most appropriate scale for understanding world distribution patterns.

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Ecosystems and Biomes• Eleven major types

– Often significant and even predictable relationships exist between the biota (particularly the flora) of a biome and the associated climate and soil types.

• Ecotone—the transition zone between biotic communities in which the typical species of one community intermingle or interdigitate with those of another. Marsh/mangrove ecotone with fire, freeze,

and hurricane damage. Taken September 20, 2001

Terrestrial Flora• Geographers interested in

natural vegetation of landscape for three reasons:1. Plants are likely to dominate

a landscape (except where terrain is rugged, climate is harsh, or humans have intervened);

2. Vegetation is a sensitive indicator of other environmental attributes;

3. Vegetation is often instrumental to human settlement and activities.

Characteristics of Plants• Most very hardy.• High survival potential

dependent on:– Subsurface root system– Reproductive mechanism

• Perennial—plant that can live more than a single year despite seasonal climatic variations.

• Annual—plant that perishes during times of climatic stress but leaves behind a reservoir of seeds to germinate during the next favorable period.

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Characteristics of Plants• Common

characteristics:– Roots (to gather

nutrients and moisture and to anchor plant);

– Stems and branches (to support and transport nutrients);

– Leaves (to collect solar energy, exchange gases, and transpire water);

– Reproductive organs.

Floristic Terminology• Categorizing by

reproduction: – Through spores

• Those that reproduce by spores are in two major groups:

– Bryophytes—spore-bearing plants such as mosses and liverworts; never dominated in history, but can be very important in some localized situations.

– Pteridophytes—spore-bearing plants such as ferns, horsetails, and clubmosses; used to dominate continental vegetation, but no more.

Spores

Bryophytes

Pteridophytes

Floristic Terminology– Through seeds

• Those that reproduce by seeds are in two major groups:

– Gymnosperms—seed-reproducing plants that carry their seeds in cones; also known as conifers.

» Used to be more important, in geologic past.

– Angiosperms—plants that have seeds encased in some sort of protective body, such as a fruit, a nut, or a seedpod.

» Have dominated planet vegetation for last 50 million to 60 million years.

Seeds

Gymnosperms

Angiosperms

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– Other terms

– Fig. 11-3

Trees

Gymnosperms

Angiosperms

SoftwoodConiferousNeedleleaf

HardwoodDeciduousBroadleaf

Floristic Terminology• Categorizing by stem or trunk

composition:– Woody plant—plant that has stem

composed of hard fibrous material; refers mostly to trees and shrubs.

– Herbaceous—refers to plants that have soft stems; mostly grasses, forbs, and lichens.

• Categorizing by leaf retention:– Deciduous—refers to trees that

experience an annual period in which all leaves die and usually fall from the tree, due either to a cold or dry season.

– Evergreen—a tree or shrub that sheds its leaves on a sporadic or successive basis, but at any given time appears to be fully leaved.

Floristic Terminology• Categorizing by leaf

shape:– Broadleaf—tree that has

flat and expansive leaves.• Majority are deciduous.• In rainy tropics, everything

is evergreen.– Needleleaf—refers to trees

adorned with thin slivers of tough, leathery, waxy needles rather than typical leaves.

• Almost all are evergreen.

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Floristic Terminology

• Categorizing by supposed structure—but this is unsatisfactory.– Hardwood—angiosperm

tree that is usually broad-leaved and deciduous. Wood has a relatively complicated structure, but is not always hard.

– Softwood —gymnosperm tree; nearly all such trees are needle-leaved evergreens with wood of simple cellular structure but not always soft.

Environmental Adaptations

• Two prominent adaptation strategies of plants to protect against environmental stress are– Xerophytic adaptations– Hygrophytic adaptations

Environmental Adaptations• Xerophytic—refers to

plants structurally adapting to withstand protracted dry conditions. – Roots, stems, leaves,

reproductive cycle can all adapt in various ways.

• Succulent—plant that has fleshy stem that stores water.

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Environmental Adaptations• Hygrophytic—refers to

plants structurally adapting to withstand protracted wet conditions.

• HygrophyticAdapatation– Hygrophyte—plant that

requires a saturated or semi-saturated environment (frequent soakings with water).

Environmental Adaptations• Likely to have extensive root

system for anchoring in soft ground.

• Usually relies on buoyancy of water for support rather than stem.

• Many have weak, pliable stems so can withstand currents.

• Hydrophytes are often grouped in with this category.– Hydrophyte—a “water-loving” plant

that is adapted to live in more or less permanently immersed in water.

Environmental Adaptations• Hygrophytic Adapatation

– Hygrophyte—plant that requires a saturated or semi-saturated environment (frequent soakings with water).

– Likely to have extensive root system for anchoring in soft ground.

– Usually relies on buoyancy of water for support rather than stem.

– Many have weak, pliable stems so can withstand currents.

• Hydrophytes are often grouped in with this category.– Hydrophyte—a “water-loving” plant

that is adapted to live in more or less permanently immersed in water.

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The Critical Role of Competition

• Competition is key in which plants grow where.– Even though all

conditions (climatic, edaphic, etc.) are favorable, a plant may not take hold in one area because of competition.

Kudzu Vine

Spatial Groupings of Plants

• Geographers usually more concerned with spatial groupings than individual plants.– Groups based on

dominant members, dominant appearance, or both.

Spatial Groupings of Plants• Floristic pattern of Earth is

impermanent.• Change can be slow and

orderly, as in lake infilling.• Change can be abrupt and

chaotic, as in wildfire.– Climax vegetation—a stable

plant association of relatively constant composition that develops at the end of a long succession of changes.

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Spatial Groupings of Plants• Is an association in

equilibrium with prevailing environmental conditions.

• Should persist until environmental disturbance/change occurs.

• Seral association—various stages leading up to climax vegetation.

Spatial Groupings of Plants• Geographers can face significant difficulties in

recognizing spatial groupings.• As one tries to identify patterns and recognize

relationships, must make generalizations.– When associations are portrayed on maps,

boundaries usually represent approximations.– Human interference plays a major role.– Because of human impact, climax vegetation is now

the exception rather than rule.• Maps often ignore human interference, so are

actually maps of theoretical natural vegetation.

Spatial Groupings of Plants• Many ways to classify

plant associations.– Geographers usually

place emphasis on structure and appearance of dominant plants.

– Major associations include forests, woodlands, shrublands, grasslands, deserts, tundra, and wetlands.

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– Fig. 11-7

Spatial Groupings of Plants• Forest—an assemblage of trees growing closely together so that

their individual leaf canopies generally overlap.– Likely to become climax association in any area where moisture is

adequate and growing season isn’t very short.• Woodland—tree-dominated association in which the trees are

spaced more widely apart than those of forests and do not have interlacing canopies.

• Shrubland —plant association dominated by relatively short woody plants.– Wide latitudinal range but usually restricted to semiarid or arid areas.

Spatial Groupings of Plants• Grassland—plant association dominated by grasses and forbs.

– Prominent types are savanna, prairie, and steppe.– Associated with semiarid and subhumid climates.

• Desert—actually a climate, not an association per se, but is typified by plants widely scattered on bare ground.

• Tundra—a complex mix of very low-growing plants, including grasses, forbs, dwarf shrubs, mosses, and lichens, but no trees.– Only in the perennially cold climates of high latitudes or high altitudes.

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Spatial Groupings of Plants• Wetland—landscape

characterized by shallow, standing water all or most of the year, with vegetation rising above the water level.– Have much more

limited geographic extent than any other above associations.

Carson River, NV

Spatial Groupings of Plants• Various plant associations will exist in

relatively narrow zones when mountain slopes have significant elevationalchanges in short horizontal distances.– Vertical zonation—the horizontal layering

of different plant associations on a mountainside or hillside.

• Elevation changes are counterpart of latitude changes.

• Treeline elevation varies with latitude.• Southern and Northern hemispheres

experience different elevation–latitude relationship, with Southern Hemisphere having lower treelines.

• Reason for discrepancy is not understood yet.

• Can have significant local variations caused by a variety of local environmental conditions.

– Fig. 11-10

– Vertical Zonation• Most apparent in mountains due to changes in

elevations over short distances

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Spatial Groupings of Plants• Exposure to sunlight is often a critical determinant of

vegetation composition.– Adret slope—Sun slope; slope where Sun’s rays arrive at a

relatively direct angle. • Relatively hot and dry, and its vegetation is sparser and smaller

than that on adjacent slopes with different exposures.• Likely to have species composition different from adjacent slopes.

– Ubac slope—a slope where sunlight strikes at a low angle and hence is much less effective in heating and evaporating than on the adret slope, thus producing more luxuriant vegetation of a richer diversity.

• Difference between adret and ubac decreases with increasing latitude.

• Valley-bottom locations can have vegetation composition significantly different from slopes running to it.

– Local Variations• Exposure to sunlight

– Mountainous landscapes

– Fig. 11-13

– Local Variation (continued)• Valley-bottom location

– Fig. 11-14

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Spatial Groupings of Plants

• Riparian vegetation—streamside growth, particularly prominent in relatively dry regions, where stream courses may be lined with trees, although no other trees are to be found in the landscape.

Terrestrial Fauna

• Animals occur in much greater variety than plants over Earth.

• Animals, however, tend to be much less prominent than plants in the landscape.

• They tend to be secretive and inconspicuous.

• Also, environmental relationships are much less clearly evidenced by animals than plants.

• Their inconspicuousness makes it more difficult to study them, and their mobility had lead to greater environmental adaptability among them.

Characteristics of Animals• Variety of animal life

is so great that it is difficult to find many unifying characteristics.

– Two universal traits (though these aren’t always immediately recognizable):

1. Mobility2. Need to eat plants

and/or other animals

The tree of life at Animal Kingdom

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• Characteristics of Animals– Great diversity– Two universal features

• Motile• Heterotrophs

– Consumers (incapable of manufacturing food from air, water and sunlight like plants do)

– Fig. 11-15, 16, 19a, 21, & 27

Kinds of Animals• Size and habits are not valid indicators of animal’s significance to

geographic study.• Minute and seemingly inconsequential organisms can play important roles.• Examples are carriers of disease, providers of scarce nutrients.• More than 90% of all animal species are invertebrates (without backbones).• Arthropods most prominent (insects, spiders, centipedes, millipedes,

crustaceans).• Five groups of vertebrates, those with backbone:

– Fish, amphibians, reptiles, birds, and mammals.

• Kinds of Animals– Invertebrates– Vertebrates

• Fishes• Amphibians• Reptiles• Birds• Mammals

– Fig. 11-15, 16, 19a, 21, 27 & 11-17

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Kinds of Animals• Most mammals are

placentals, having young grow and develop in mother’s body.– About 135 species are

marsupials, in which mothers carry young, not fully developed at birth, in pouches.

– Two species are monotremes—lay eggs.

• Echidna and duckbill platypus.

Environmental Adaptations

• Three different kinds of evolutionary adaptation by animals:

1. Physiological2. Behavioral3. Reproductive

Example of Animal Adaptations to Desert Life

• Faunal diversity can be astounding in desert areas where water is permanent or prolonged.

• Even in areas where open water is not available, there are pockets of localized favorable habitat that permit remnant populations to survive.

• Most animals are completely nocturnal.

• Animals are more conspicuous when cooler, such as at night and winter.

• Some animals follow rains in nomadic fashion.

• Most prominently displayed by birds.

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Example of Animal Adaptations to Desert Life

• Some spend significant time underground.

• Some bury selves to survive long dry spells, such as freshwater crayfish and crabs.

• Text provides detailed discussion of anatomical and physiological adaptations.

• A few species of rodents can exist from birth to death without ever taking a drink.

• Get moisture from food.• Some species display ability to delay

reproductive processes over long dry periods until more favorable conditions occur.

• Australian desert kangaroos can delay implantation of fertilized blastocyst, so it remains in inactive state in uterus until better weather conditions occur.

Competition Among Animals• Competition can be

both direct and indirect.

• Indirect—rivalry for space and resources.

• Direct—antagonism of predation.

• Many create social groups among own species.

Competition Among Animals• Some across species, such as

communal relationship among zebras, wildebeest and impalas in East African savannas.

• Individual animals are concerned either largely or entirely with own survival.

• Some animal species concerned with survival of mates.

• Some concerned with survival of young (more common as maternal instinct, though some paternal too).

• Still fewer concerned with survival for group.

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Cooperation among Animals• Symbiosis—association of two

dissimilar organisms, in which they live together in some fashion.

• Mutualism—symbiotic relationship in which the association is mutually beneficial to both organisms.

• Commensalism—symbiotic relationship in which the association is neither beneficial nor injurious to either.

• Parasitism—symbiotic relationship, in which the association benefits one, but harms the other; that is, one lives on or in the other, to detriment of the host.

Symbiosis

Mutualism Commensalism Parasitism

Zoogeographic Regions• Animals’ distribution

patterns more complex and irregular because of their mobility.

• The broad distributions of animals nevertheless do reflect a general distribution of energy and food diversity.

Zoogeographic Regions

• Nine zoogeographic regions are generally recognized.

• Represent average conditions and cannot portray some common pattern in which different groups of animals fit precisely.

• Map on page 329.

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Zoogeographic Regions• Reflective of the general distribution of energy

and richness of food chemistry

– Fig. 11-23

Zoogeographic Regions• Ethiopian Region

– Has most diverse vertebrate fauna and greatest number of mammalian families.

• Oriental Region– Similar to Ethiopian but with

less diversity (save for birds and reptiles; large number of venomous snakes).

• Palearctic Region– Poorer fauna than previous

two; – Probably function of higher

latitudes and more rigorous climate.

• Palearctic Region– Separated from rest of Eurasia by mountains– Few endemic species, fewer species than in tropics

– Fig. 11-23

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• Nearctic Region– Non-tropical portions of North America– Similar to Palearctic due to Bering land bridge

– Fig. 11-23

Zoogeographic Regions• Nearctic Region

– Faunal assemblage relatively poor (save for being well-represented with reptiles).

– Largely a transitional zone between Palearctic and Neotropical groups.

– Great similarity to Palearctic, so that some group together into superregion, Holoarctic.

– Reflects how faunal dispersal occurred via Bering land bridge in geologic past.

• Neotropical Region– Has rich and distinctive faunal assemblage:– Variety of habitats and isolation from other

regions;– Has a larger number of endemic mammal

families than any other region;– Bird fauna is exceedingly diverse and

conspicuous.

Zoogeographic Regions

• Madagascar Region– Dominated by relic

assemblage of unusual forms.

– Primitive primates (lemurs).• New Zealand region

– Fauna dominated by birds (mostly flightless).

– Almost no terrestrial vertebrates.

– No mammals and only a few reptiles and amphibians.

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Zoogeographic Regions• Pacific Islands Region

– Limited faunal assemblage.• Australian Region

– Has most distinctive fauna of any region.– Lack of variety is made up by animals’ uniqueness.– The Unique Biota of Australia– More than 90% of the native tree species in Australia are of the

single genus, Eucalyptus. • Above should either be “a single genus, Euc” or “the single genus

Euc” (no comma)– These trees, which there are greater than 400 species of, are

native only to Australia.– The shrubs and bushes of Australia are dominated by a single

genus, Acacia.– The dominance of this genus is attributed to isolation.

– Australia Region• Australia and

adjacent islands• Most distinctive

fauna of any region due to the region’s lengthy isolation– Few placental

mammals• Its unique biota are

also primarily a result of isolation – Fig. 11-17: Kangaroo. Fig. 11-18:

Monotremes (egg-laying mammals) Echidna and duckbill platypus.

Zoogeographic Regions• Australian fauna is also unique

because of isolation. – Australian fauna is dominated by a

single primitive mammalian order, marsupials.

– The continent is also the only home to the primitive monotremes.

– Marsupials and monotremes were able to flourish in relative isolation from competitive and predatory pressures that influenced animal evolution in other parts of the world.

– As such, indigenous placental mammals are lacking on the continent.

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The Major Biomes

• Named for dominant vegetation, but encompasses fauna as well as interrelationships with soil, climate, and topography.

Major Biomes• Summary of each

biome follows…– Distribution (map)– Climate types– Main vegetation

types– Limiting factors to

flora and fauna

– Fig. 11-25 (left panel, p. 330)

– Fig. 11-25 (right panel, p. 331)

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The Major Biomes• Tropical Rainforest

– Selva — tropical rainforest; a distinctive assemblage of tropical vegetation that is dominated by a great variety of tall, high-crowned trees.

• Probably most complex of all terrestrial ecosystems.

– Distribution closely related to climate.

– Consistent rainfall and relatively high temperatures.

– Layered structure, with second layer being a branch canopy formed by the high trees that crest above the canopy.

– Undergrowth relatively sparse because of lack of light.

– Interior is region of heavy shade, high humidity, windless air, continuous warmth, aroma of mold and decomposition.

– Fauna is largely arboreal—tree dwelling.

– Canopy serves as principal food source.

The Major Biomes• Tropical Deciduous Forest

– Not closely correlated with specific climatic types; distribution more irregular and fragmented.

– Compared to rainforest, canopy is less dense, trees are shorter, and there is less diversity of tree species (but greater variety of shrubs and other lesser plants).

– Response to either less total precipitation or less periodic precipitation.

– Many trees shed leaves at same time, so more sunlight can penetrate.

– Produces classic jungle conditions.

The Major Biomes• Tropical Scrub

– Widespread in drier portions of A climatic realm (covers extensive areas in tropics and subtropics).

– Dominated by low-growing scraggly trees and tall bushes, usually with extensive understory of grasses.

– Plant species diversity less than that in tropical rainforest and tropical deciduous.

– Faunal diversity very different from tropical rainforest and tropical deciduous.

– Moderately rich assemblage of ground-dwelling mammals and reptiles, and of birds and insects.

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The Major Biomes• Tropical Savanna

– Distribution of biome doesn’t exactly correlate with distribution of tropical savanna climate.

– Incomplete correlation most noticeable where seasonal rainfall contrasts are greatest (which is associated with annual shifting of the intertropical convergence zone [ITCZ]).

– Dominated by tall grasses.– Some regions actually former

tropical deciduous forest and even tropical rainforest, but humans converted it through fires and by grazing domestic animals.

– Has a very pronounced seasonal rhythm: wet season, dry season, and wildfire season.

– Savanna fauna varies according to continent.

– Africa has most remarkable, diverse large wildlife.

– Latin America has only sparse population of large wildlife.

The Major Biomes• Desert

– Occurs extensively in midlatitude locations in Asia, North America, and South America with a fairly close correlation to Bwh and Bwkclimates.

– Vegetation surprisingly variable.

– Shrubs are typical, with succulents common in drier parts.

– Trees can be found, particularly in Australia.

– Most deserts have moderately diverse faunal assemblage.

– Variety of large mammals is limited.

The Major Biomes• Mediterranean Woodland and

Shrub– Six widely scattered and relatively

small areas in midlatitudes.– Have pronounced dry-summer

wet-winter precipitation.– Dominant vegetation associations

are physically similar, but taxonomically quite varied.

– Dominated by dense growth of woody shrubs, but also have open grassy woodlands.

– Plant species vary from region to region, but in all, the trees and shrubs are primarily broadleaf evergreens.

– Many plants are adapted to rapid recovery after wildfire.

– Fauna not particularly distinctive.– Seed-eating, burrowing rodents

common.– General overlap of animals

between this biome and adjacent ones.

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The Major Biomes• Midlatitude Grassland

– Locational coincidence between this biome and steppe climatic type is very pronounced in Northern Hemisphere.

– Less distinct climatic correlations in Southern Hemisphere.

– Occurs widely in midlatitudes of North America and Eurasia.

– Low precipitation and/or frequency of fire prevent growth of tree or shrub seedlings.

– Characteristics of grasses depends on moisture: taller in wetter area (prairie), shorter in dryer (steppe), and sometimes not continuous, but grow in discrete tufts.

– Before human encroachment, fauna comprised of large numbers of relatively few species, with migratory larger herbivores.

The Major Biomes• Midlatitude Deciduous Forest

– Used to be far more extensive in all Northern Hemisphere continents and to some extent in tracts in Southern Hemisphere.

– Humans have cleared away large portions for agriculture.

– Fairly dense growth of tall broadleaf trees with complete canopy in summer.

– Winter very different, with seasonal fall of leaves.

– Tree species vary greatly from region to region.

– Generally has the richest assemblage of fauna in midlatitudes.

– Seasonal variation to fauna (hibernation and migration).

The Major Biomes• Boreal Forest

– An extensive needleleaf forest in subarcticregions of North America and Eurasia; also called taiga.

– One of most extensive biomes, occupying vast expanse of northern North America and Eurasia.

– Close correlation with subarctic climatic type.– Has perhaps simplest assemblage of plants.– Most trees are conifers, though in some

places deciduous trees interrupt the coniferous cover.

– Trees become spindlier, short, and openly spaced in north.

– Bogs and swamps numerous because of permanently frozen subsoil and derangement of normal surface drainage from past glaciers.

– Faunal diversity limited because of limited food supply.

– Populations of some species can fluctuate enormously in space of year or so.

– Insects absent in winter but superabundant in brief summer.

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The Major Biomes• Tundra

– Distribution along northern edge of Northern Hemisphere continents.

– Essentially a cold desert or grassland.

– No trees, but considerable mixture of species (grasses, mosses, lichens, flowering herbs, and a scattering of low shrubs).

– Dominant animal life consists of bird and insects during summer.

– Few species of mammals and freshwater fishes and almost no reptiles or amphibians.

The Major Biomes

• Alpine Tundra– Found in many

high-elevation regions.

– Above timberline there is sparse vegetation cover, consisting mostly of herbaceous plants, grasses, and low shrubs.

Human Modification of Natural Distribution Patterns

• Human activities severely alter natural distribution patterns of biota.

• Humans directly influence biotic distributions in three ways:

1. Physical removal of organisms2. Habitat modification3. Artificial translocation of organisms

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Physical Removal of Organisms

• Humans severely modify landscape, affecting both plants and animal inhabitants.

• Cut down, plow up, pave over, burn out, poison, shoot, trap, otherwise eradicate.

– Fig. 11-41. Central America – one of highest rates of deforestation (due mainly to expansion of cattle ranching)

Habitat Modification• Humans affect native

plants and animals by changing their habitat.

• Humans change soil environment through farming, grazing, engineering, and construction.

• Humans degrade atmospheric environment through pollution.

• Humans impound, divert, and pollute waters.• Removal for agriculture often

• results in soil erosion and • low crop yields as well as • wildlife habitat destruction.

Tropical Rainforest Removal• One of Earth’s most serious environmental problems, as

of last decade or so.• Rate of deforestation = 51 acres (21 hectares) per

minute.• More than half of original African rainforest is now gone,

about 45% of Asia’s and close to 40% of Latin America’s.

• Current situation varies in five major rainforest regions.• In mid-1980s, extinction rates = about 1 species per day.• In mid 1990s, extinction rates = about 2 species per

hour.

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Tropical Rainforest Removal

• Loss of forest also contributes to:– Accelerated soil erosion– Drought– Flooding– Water-quality degradation– Declining agricultural productivity– Greater poverty for rural inhabitants– Increasing atmospheric carbon dioxide (greenhouse

effect).– Anticipated economic benefits are usually illusory.

Tropical Rainforest Removal• Continuous heavy (and expensive) fertilization necessary for

sustainable agriculture.• Losing potential valuable resources—pharmaceutical products, new

food crops, natural insecticides, industrial material, and crop hybridizations (for resisting disease, insects, parasites, and other environmental stresses).

• Development of agroforestry (the planting of crops with trees) to counteract some of the destruction.

• UNESCO project to set aside reserves to protect biodiversity. • At present about 300 preserves have been established in more than

75 countries, encompassing 12 million hectares.• Artificial Translocation of Organisms

Tropical Rainforest Removal• Humans have introduced many

wild plants and animals into “new” habitats.

• Exotic species—organism that is introduced into “new” habitats in which it did not naturally occur.

• Sometimes deliberate, sometimes accidental.

• Exotics have had great impacts (cats on flightless bird populations in New Zealand, European flea in all parts of world).

Walking Catfish, Florida

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Biotic Rearrangement: The Sad Case of Florida

• Human actions in introducing exotic (nonnative) species result in usually one of two extremes:

• Either exotic dies out in a short time; or• It flourishes extraordinarily.• When flourishes, can occasionally have a

salutary effect, but many cases either unsatisfactory or absolutely disastrous.

Biotic Rearrangement: The Sad Case of Florida

• Florida presents perhaps the most frightening case study.

• In last decade or so, state has experienced one of highest in-migration of people anywhere.

• Has created massive disruptions in ecosystems, and exotics are most likely to prosper when ecosystem is unstable.

• Artificial drainage provides routes for easy dispersal of aquatic organisms.

• Has become the major world center for animal-import industry.

• Has become almost as important in plant import industry.• Inevitable that many escape (some are turned loose).

Biotic Rearrangement: The Sad Case of Florida

• Dozens of species of exotic plants have become widespread, and most are expanding their ranges.

• Spread of melaleuca tree has changed swamps to forests.

• Aquatic weeds infest more than half a million acres of waters.

• Many exotic animal species well established and some spreading rapidly.

• Exotic fish more numerous and pose even more serious problems, competing with native species.

• Greatest present and potential threat is so-called walking catfish from Southeast Asia.

Salt Cedars

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Focus: Desert Adaptations of the Amazing Camel

• Dromedary (one-humped) camel has developed the most remarkable series of adjustments to desert environment.

• Anatomical adaptations include• Light-colored and shiny summer coat reflects hot

sunlight.• Deeply cleft upper lip allows moisture loss from

nose to be recycled back into mouth.• Nostrils are horizontal slits that keep sand and

dust out.

Focus: Desert Adaptations of the Amazing Camel

• Eyes set beneath shaggy brows for shade, and double eyelids to protect eyes from sand.

• Broad and elastic feet for good traction and protection against the hot sand.

• Physiological adaptations include• Highly fluctuating body temperatures that allow them to

conserve moisture through minimal perspiration. • Little production of urine and little moisture voided in

their feces.• Can stand long periods without water and can rapidly

rehydrate when drinking.• They cannot, however, store moisture in their hump.

People and the Environment: Rainforest Loss in Brazil

• Brazil contains about one-third of the planet’s tropical rainforest. • Settlement over the last 50 years in the forest has led to large tracts

of it being cleared for settlement and logging.• This clearing has been facilitated by the construction of the Cuiabá-

Port Velho highway.• By the late 1980s deforestation had increased substantially, and by

2001 the amount removed was extraordinary.• In 2004, more than 26,000 square kilometers of rainforest were lost.• Much of the land is cleared for grazing land, which is then

abandoned after a couple of years due to the poor fertility of tropical soils.

• This is leading to habitat and species loss in the region.