BIOL 4120: Principles of EcologyBIOL 4120: Principles of Ecology

Lecture 5: Biome Concept in Lecture 5: Biome Concept in EcologyEcology

Dafeng HuiDafeng Hui

Room: Harned Hall 320Room: Harned Hall 320

Phone: 963-5777Phone: 963-5777

Email: dhui@tnstate.eduEmail: dhui@tnstate.edu

TopicsTopics

5.1 Climate is the major determinant of plant growth form and distribution

5.2 Climate determine the boundaries of terrestrial biomes5.3 Walter climate diagrams distinguish the major climate

biomes5.4 Temperate climate zones have average annual

temperature between 5 and 20oC5. 5 Boreal and polar climate zones have average

temperatures below 5oC5. 6 Climate zones with tropical latitudes have average

temperatures exceeding 20oC5.7 Biome concept must be modified for freshwater

aquatic systems5.8 Marine aquatic systems are classified principally by

water depth

Biomes are classified according to the

predominat plant types and climate

Concept of Biomes:

F.E. Clements and V.E. Shelford, 1939

Combining broad-scale distribution of both plants and associated animals into a single classification

Biomes: classified according to the predominant plant types

Campbell 1996: the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment.

Biomes reflect adaptations of dominant plant life forms

Why are there consistent patterns in the distribution and abundance of three dominant plant life forms that relate to climate and physical environment?

Three general plant forms: trees, shrubs, and grasses.

Biomes reflect adaptations of dominant plant life forms

These three forms represent different patterns of carbon allocation and morphology

Grasses: less C to production of supporting tissue (stem) than do wood plants (shrubs and trees), more to photosynthetic tissues (leaves)

Woody plants: shrubs allocate lower percentage to stem than trees.

Trees: more to stem, advantage of height and access to light, cost more for maintenance and respiration.

As environmental conditions become adverse for photosynthesis (dry, low nutrient, cold T), trees will decline in both stature and density until they are no longer able to persist as a component of the plant community.

Forests

Within broad classes of forest and woodland ecosystem (trees are dominant or co-dominant), leaf form is another plant characteristic.

Based on longevity of leafDeciduous (live for only one year or growing season)• Winter-deciduous (temperate regions, low winter T)• Drought-deciduous (subtropical and tropical, leaf shed on

dry periods)Evergreen (live beyond a year)• Broadleaf-evergreen (tropic rainforest, no distinct growing

season, year-round photosynthesis)• Needle-leaf evergreen (growing season is short or nutrient

availability constrains photosynthesis and plant growth)

Economic model to explain adaptation of leaf form: cost to produce leaf and gain from photosynthesis.

Concept of Biomes:

Major terrestrial biome types (eight , nine, and varies):

Tropical forest, temperate forest, conifer forest (taiga and boreal forest), tropical savanna, temperate grasslands, chaparral (shrublands), tundra, and desert.

5.1 Climate is the major determinant of plant growth form and distribution

Since organisms are adapted to the physical environments of their biomes, ranges of species are limited by these physical conditions

In terrestrial environments, temperature and moisture are the most important variables, particularly for plants.

Related species may differ in their ecological tolerances, and distribute Differently

5.2 Climate defines the boundaries of terrestrial biomes (Walter)

Robert Whittaker, Cornell Uni.

Biomes and climate

Boundaries between biomes are broad and often indistinct

Other factors: topography, soils, and exposure to disturbances such as fire

Nashville, TNNashville, TN

Mean temperature: 14.9 oC, annual precipitation: 122.3 cmSource: US Climate Data

Temperate seasonal forest

Robert Whittaker, Cornell Uni.

Biomes and climate

Boundaries between biomes are broad and often indistinct

Other factors: topography, soils, and exposure to disturbances such as fire

BIOL 4120: Principles of EcologyBIOL 4120: Principles of Ecology

Lecture 5: Biome Concept in Lecture 5: Biome Concept in EcologyEcology

Dafeng HuiDafeng Hui

Room: Harned Hall 320Room: Harned Hall 320

Phone: 963-5777Phone: 963-5777

Email: dhui@tnstate.eduEmail: dhui@tnstate.edu

RecapRecap

Climate and soilSoil profile, soil weathering process, soil order

BiomesClimate is the major determinant of plant growth form and

distribution

Climate determine the boundaries of terrestrial biomes

5.3 Walter climate diagrams distinguish the major terrestrial biomes

Precipitation and temperature interactively determine biomes

To permit ecologically meaningful comparisons of climates between localities, Walter developed a climate diagram to illustrate seasonal periods of water deficit and abundance.

Each climate zone has a typical seasonal patterns of T and P.

5.4 Temperate climate zones have average annual temperature between 5 and 20oC

Temperate seasonal forest biome (Climate zone VI)

Temperate rain forest biome (Climate zone V)

Temperate grassland/desert biome (Climate zone VII)

Woodland/shrubland biome (climate zone IV)

Subtropical desert biome (climate zone III)

Temperate seasonal forest

Forest ecosystems dominate the wetter regions of the temperate zone

Deciduous forest covered large area of Europe and China, but mostly converted to croplands, only exist in eastern China

North America, deciduous forests consist of a number of associations (next slide)

Southern Hemisphere, temperate evergreen forest become predominant

Asiatic broadleaf forest found in eastern China, Japan, Korea is similar to the North American deciduous forest

Large scale distribution of temperate forest in eastern US

Grassland ecosystems

Rainfall is very important: 250 to 800 mmOther factors: fire, and human activity

(convert grassland to desert by overgrazing)

Area: dropped from 42% to <12% of original size

Location: mid-latitudes in mid-continental regions

Typical: prairies of North America, steppes of central Eurasia

Grassland in North America

a.Tallgrass prairie in Iowa,

b.mixed-grass prairie;

c.shortgrass steppe

Tallgrass prairie

Big bluestem, >1m

Mixed-grass prairie

Needlegrass-garma grass

Shortgrass prairie

Blue garma and buffalo grass

Aboveground primary productivity is related to MAP (52 grassland)

Grasslands are most productive when MAP>800 mm and MAT > 15oC

5.4 Temperate climate zones have average annual temperature between 5 and 20oC

Temperate seasonal forest biome (Climate zone VI)

Temperate rain forest biome (Climate zone V)

Temperate grassland/desert biome (Climate zone VII)

Woodland/shrubland biome (climate zone IV)

Subtropical desert biome (climate zone III)

sclerophyllous: hard-leaved vegetation

Desert

Area: 25 to 35%Location: latitudes between 15 and 30oCause: Global air mass circulation T: High in summer, could be cold in winterPPT: low, <150 mmTypical examples: majority in Northern

Hemisphere, Sahara in Africa, Gobi in Asia, western North America

Deserts are not the same everywhere

Cold desert: Great Basin of North America, the Gobi, Takla Makan, and Turkestan deserts of Asia

Species: sagebrush, shadscale, chenopods, etc

Hot desert: Mojave, the Sonoran, and Chihuahuan

Vegetation: none to some combination of chenopods, dwarf-shrubs, and succulents

Hot desert: a. Chihuahuan Desert, b. Great Victorian Desert in Australia, c. Dunes in Saudi Arabian desert.

Plants and animals in DesertSurvive of desert plants:

Adapted to scarcity of water, low primary productivityFlowering only when moisture is presentFast grow, flower, produce seeds and dieDeep-rooted (mesquite, taproots reach water table)CAM pathway, special leaf structure

Survive of animalsSupport a diversity of animal life (bettles, ants, locusts, lizards, snakes, birds and mammals)Grazing herbivores: generalists, consume a wide range of species. Desert carnivores, such as fox and coyotes, have mixed diet include leaves and fruits.

5. 5 Boreal and polar climate zones have average temperatures below 5oC

Boreal forest biome (Climate zone VIII)

Tundra biome (Climate zone IX)

Black spruce in North America taiga (boreal forest)

Some coniferous forest. A. Norway spruce, b. Rocky Mountaine subalpine forest, c. montane coniferous forest in Rocky Mountains

Arctic TundraTundra is treeless plainArctic tundra is a frozen plain, clothed in sedges, heaths, and

willows, dotted with lakes, and crossed by streams

Cold Temperature and low precipitation

Two types:Polar desert: dry soil, less than 5% plant cover

Wet tundra: up to 100% plant coverage, wet to moist soil

Unique conditions:permafrost: isolate and protect soil OMvegetation: simple form, slow growth, allocate more to roots.

Arctic tundraCanada

Rocky Mountains alpine tundra

5. 6 Climate zones with tropical latitudes have average temperatures exceeding 20oC

Tropical rain forest biomes (Climate zone I)

Tropical seasonal forest/savanna biome (Climate zone II)

Tropic rain forest

Location: Equatorial zone between latitudes 10 oN and 10 oS

T: warm all year, monthly mean T>20 oC

PPT: Rainfall occurs daily, min. monthly>60mm

Typical example: Amazon basin of South America

RecapRecap

Climate zone with temperate climate zones have average temperatures between 5 and 20 oC

Boreal and polar climate zones have average temperatures below 5oC

Climate zones with tropical latitudes have average temperatures exceeding 20oC

Tropic rain forests in Amazon (a), Malaysia (b), and Northeast Australia (c)

High net primary productivity (NPP)

High diversity of plant and animal life

7% land surface, >50% plant and animal species

10-km2 contain 1500 species of flowing plants and 750 tree species.

Richest area in Malaysia, 7900 species

90% of all primate species live in the tropical rain forest

orangutan (an arboreal ape)

Gibbons, langurs, macaques

(Malaysian)

Gorillas, and chimpanzees

(Africa)

Lemurs

Beetles, butterflies

Vertical stratification of a tropic rain forest

Tropical Savannas

Location: Equatorial zone between latitudes 30oN and 30oS, Dry tropic and subtropical.

T: warm all year, annual mean T>18oCPPT: distinct seasonality in rainfall,

large interannual variationTypical example: South America

Tropical SavannasSavanna: means the treeless areas of South America

Grassland with scattered trees.

Characteristics:Occur on land surfaces of little relief, often on old plateaus,

dissected by rivers, soil poor in nutrients, especially PDominant species are fire-adapted, subjected to recurrent

fires.Grass cover with or without wood vegetation is always presentWoody component is short-lived (less than a few decades).

Two-layer vertical structure (ground level grass + shrubs or trees)

Support a large and varies assemblage of herbivores, invertebrate and vertebrate, grazing and browsing.

Interaction between annual PPT and soil texture in defining biomes

Access by plants to soil moisture is more limited on the heavy textured soils (clay) than sandy oil.

5.7 Biome concept must be modified 5.7 Biome concept must be modified for aquatic systemsfor aquatic systems

Terrestrial biomes: classified by growth form of Terrestrial biomes: classified by growth form of dominant vegetation reflects climate conditions.dominant vegetation reflects climate conditions.

Aquatic biomes: in many aquatic systems, there is Aquatic biomes: in many aquatic systems, there is no “vegetation” form, only algaeno “vegetation” form, only algae

Classified primarily by physical characteristics Classified primarily by physical characteristics such as salinity, water movement, and depthsuch as salinity, water movement, and depth

Freshwater aquatic:Freshwater aquatic: Flowing water: Streams and riversFlowing water: Streams and rivers Standing water: lakes and pondsStanding water: lakes and ponds WetlandsWetlands EstuariesEstuaries

Flowing water: streams and riversLotic systems: flowing fresh waters, such as streams and rivers

Streams form wherever P exceeds ET, and excess water drains from the land.

Riffles: water runs rapidly over a rocky substratumPools: deeper stretches of more slowly moving water

Riparian zone: terrestrial veg influenced by seasonal floodingAllochthonous: organic material that enters the aquatic system from the outsideAutochthonous: home grow its organic material.

Lack richness and diversity

Fluvial systems, as rivers are sometimes called

Standing water: lakes and ponds

Lentic system: nonflowing water systems, such as lakes and ponds

Layers of lake:

Littoral zone

Liminetic or pelagic zone

Benthic zone

Wetlands: terrestrial and aquatic communities come together

Lands consisting soil saturated with water and supports vegetation that specifically adapted.

Include swamps, marshes, bogs (fresh water), salt marshes and mangrove (associated with marine environments)

Plants can tolerate low O2

Important habits for a wide variety of animals, waterfowl, fish, invertebrates

Protect coastal areas from ravages of hurricanes

Wetland sediments immobilize potentially toxic or polluting substances dissolved in water and are thus natural water purifying plants.

Wetlands

Estuaries are found at the mouths of river

Mix of fresh and salt water

Extremely productivity systems

Estuaries

Human inputs into freshwater biomes

Acid rain and eutrophication

1. Acid rain: combustion of fossil fuels, sulfur dioxide, nitrogen oxides pH<4 in steams and rivers

2. Eutrophication: addition of limiting nutrients, such as N, P to aquatic ecosystems. runoff: sewage, industrial wastes, fertilizers, animal wastes from agricultural lands.

Oxygen depletion

5.8 Marine aquatic systems are 5.8 Marine aquatic systems are classified principally by water depthclassified principally by water depthVariation in marine environments:Variation in marine environments:

temperature, salinity, depth (which influence light temperature, salinity, depth (which influence light and pressure), currents, substrata and at the and pressure), currents, substrata and at the edges of ocean and tides.edges of ocean and tides.

Depth:Depth:

Littoral zone (intertide zone): extends between Littoral zone (intertide zone): extends between highest and lowest tidal water levels. highest and lowest tidal water levels.

Neritic zone: extends to depth of 200m, high Neritic zone: extends to depth of 200m, high productivity.productivity.

Oceanic zone: below neritic, sparse nutrient, low Oceanic zone: below neritic, sparse nutrient, low production.production.

Benthic zoneSeafloor below oceanic zone.

Photic zone:With sufficient light for photosynthesis

Aphotic zone: no light for photosynthesis

Open ocean === desert

But in:

Coral reefs: shallow water of warm ocean, T>20oC year around

very productive and high diverse

Like tropical rain forest in terrestrial biome

Problem: global warming, coral bleaching

Thank you!

Winter-deciduous

Drought-deciduous

Broadleaf evergreen in tropic rain forest in Australia

Needle-leaf evergreen in Sierra Nevada, US

BIOL 4120: Principles of EcologyBIOL 4120: Principles of Ecology

Lecture 5: Biome Concept in Lecture 5: Biome Concept in EcologyEcology

Dafeng HuiDafeng Hui

Room: Harned Hall 320Room: Harned Hall 320

Phone: 963-5777Phone: 963-5777

Email: dhui@tnstate.eduEmail: dhui@tnstate.edu

RecapRecap

Biomes, concept

Climate is the major determinant of plant growth form and distribution

Climate determine the boundaries of terrestrial biomes

Walter climate diagrams distinguish the major climate biomes

Temperate climate zones have average annual temperature between 5 and 20oC