l03 ecosystems biomes

Ecosystems – what types are there,

and where are they located?

Types of Ecosystems

• estuaries

• swamps and marshes

• tropical rain forest

• temperate forest

• northern coniferous forest (taiga)

• savanna

• agricultural land

• woodland and shrubland

• temperate grassland

• lakes and streams

• continental shelf

• open ocean

• tundra (arctic and alpine)

• desert scrub

• extreme desert

Miller Ch 4 Fig 4.21)

Biomes(Miller Ch 4 Fig 4.8); Cotgreave & Forseth Ch 2)

• large regions of the ecosphere containing ecosystems and communites which are similar in vegetation structure

• occur in similar overall environments (climate)

• species composition is different in the same biome in different parts of the world

BIOMES - WORLDWIDE PATTERNS OF DIVERSITY

at a world scale the vegetation is clumped into a few major types called BIOMES, based on abiotic factors

• BIOME boundaries tend to run east-west around the earth, and they reflect the climatic changes which occur from the POLES to the EQUATOR

• the pattern of BIOME distribution is determined by GROSS CLIMATE and occurs over thousands of kilometres of latitude

• day-length• temperatures• rainfall distribution

HIGH LATITUDES are characterised by TUNDRA

• LOW TEMPERATURE• LOW RAINFALL• EXTREMES of DAY LENGTH

(short “growing season”)

and characteristic groups of plants are dominant

SEDGES and DWARF TREES

LICHENS

MOSSES

TUNDRA

• moving towards the equator (LOW LATITUDES) the

• rainfall increases• temperatures rise • day length increases

and the vegetation which characterize the BIOMES changes

high latitudes

high latitudes

low latitudes

(equator)

TAIGA (BOREAL FOREST) BIOME

large areas of boreal forest - conifer forests - only in northern hemisphere

TEMPERATE DECIDUOUS or EVERGREEN FOREST BIOME (eg. Eucalyptus)

evergreen

deciduous

DESERT BIOMES

occur wherever RAINFALL is lowand unpredictable

deserts

GRASSLAND BIOMES occur whererainfall is higher and reliable

high but unreliable rainfallsresult in SAVANNA BIOMES

tropical grassland & savanna

temperate grasslands

• as a general rule, the diversity of species in a biome declines with increasing severity of climate

eg. TROPICAL BIOMES - mild climate - only 7% of land mass, but contain

50% terrestrial plants30% birds50% vertebrates90% insects

tropical biome

BUT high species diversity CAN be found in BIOMES in severe climates

eg. reptile diversity in Australian DESERT BIOME is HIGH

Threats to TROPICAL BIOMES have received most attention, but BIODIVERSITY is in serious decline in most BIOMES

BIOME orientation can be altered by mountain ranges running north-south

Rockies (USA)

Andes (South America)

Great Dividing Range (Australia)

Biome types can be altered by secondary processes such as fire, or grazing - HEATH & DRY SCLEROPHYLL (Australia), GARIQUE (Mediterranean Europe), FYNBOS (Southern Africa), CHAPARRAL (USA - California)

Heath in Australia – high endemic diversity is maintained by fire

World-scale Plant and Animal DistributionsWorld-scale Plant and Animal Distributions

• species and ecosystems can be examined in terms of compositional properties as well as structural properties

• the study of distributions shows that biomes and ecosystems with similar structures can have very different compositions, reflecting different evolutionary histories

Lydekkers line eastern limit of oriental elements

Wallacaeazone of mixing between Australian and Oriental realms mostly in last 15 million years

Wallaces line western limit of Australian elements

Oriental and Australian avifauna in Wallacaea

ali Lombok Sumbawa flores Alor

87-13 72-28 68-32 63-37 57-43

Oriental Australian

World Patterns of Plant DistributionWorld Patterns of Plant Distribution

• distribution patterns can indicate

– environmental requirements of the taxon– dispersal ability– areas of origin or diversification– evolutionary and pre-history of the taxon

Types of plant distributionsTypes of plant distributions

• the terms we use to describe distributions can imply processes, constraints, history

– Cosmopolitan species (e.g., Drosera spp.)

– Relictual families (Cycadaceae)

– Gondwanan families (Restionaceae)

– sub-antarctic (Nothofagus spp.)

– disjunct species (Eucalyptus aggregata)

– endemic genus (Isophysis tasmanica)

Macrozamia communis NSW

Regional biodiversity hotspots

• “hotspot” - a region where high biodiversity and high endemism are found, and high threat (risk of loss) sometimes coincide

• development of ‘hot-spot’ regional biotas – in situ development (e.g. SW Australia, southern Africa)– survival of ancient forms (e.g. New Caledonia, Madagascar)– mixing of elements (e.g. Oriental and Australasian bird species in

Wallacaea)– isolated islands

Regional plant diversity for selected areas

Region Area* Species Endemic Cape Prov. 90 8600 68%

SW Aust. 320 3600 68%

British Is. 308 1443 1%

New Zealand 268 2000 81%

New Caledon. 19 3000 80%

* area in thousands of square kilometres