l07 biodiversity

8/12/2019 L07 Biodiversity

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Kepentingan biodiversiti

Biodiversiti adalah pentingdan perlu di

pulihara

tetapi

kefahaman terhadapnya adalah rendah


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1. Prinsip asas:

biodiversiti mempunyai nilai intrinsik

setiap organisma mempunyai hak untuk hidup

Manusia mempunyai tanggungjawab moral

and etika untuk memuliharanya

these arguments often considered the mostimportant, but sofar, have had the least impact


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2. Manfaat ekonomi:

biodiversiti menyediaka sumber komoditi yang

boleh dipasarkan

Makanan

Bahan perubatan

agen kawalan biologi

Bahan industri

Rekreasi

tidak mengaitkan kebanyakan spesies

Menekan eksploitasi lebih daripada pemuliharaan


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3. Kemandirian :

biodiversiti menyediakan bahan tidak komersil &perkhidmatan

Fungsi ekosistem - interaksi antara organisma

with their, and our, environments

Peranan ekologi - interaksi organisma antara

satu sama lain

Pengetahuan - biologi/ekologi organisma

Nilai estetikkeseronokan pengalaman denganorganisma liar

Existence values - the values people place on

organisms although they may never encounter them


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ecosystem servicesare natural functions of anecosystem that can be, secondarily, used for

human benefit and ecological sustainabilityis thecapacity to maintain vital ecosystem processes

ecosystem services include

water and gas regulationnutrient cycling

pollination

biological control

genetic resources

landscape amenity (ecotourism)

this is why

we need to

maintain

highbiodiversity !


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a matter of survival:

an example ofecosystem servicesprovided by

riverside (riparian) vegetation

regulation of water flow

regulation of water quality - sinksfor P and N

regulation of water temperatureinput of organic food for aquatic community (fishneed trees!)

stabilization of banks - reduced erosion

creation of in-stream habitat for aquatic wildlife

enhanced fish productiontimber production

habitat for terrestrial wildlife

enhanced landscape quality


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ecosystem services

pollination services

about 90% of angiospermspecies depend on animals

esp. insectsfor pollination

human & domesticated animalsdepend (directly or

indirectly)on pollination for approx. 1/3 of their food

pollination services in agriculturalsystems in the

USA are worth 20-40 billiondollars

pollination services on a global scaleare worth 200

billiondollars

Costanza et al. (1997) Nature387, 253-260.

Kearns et al. (1998) Annual Review of Ecology and Systematics29, 83-112.


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but

agricultural pollination is carried out by European

honey-bees and some native beesnot a very

diverse group but successful ??

natural biodiversityis still important - in coffeeplantations close to forest fragments(fragments =

other species, bio-control, nest sites, food resources

when the coffee is not flowering etc.) pollination

and crop yield was 20% greaterthan in isolatedplantations (an increase of $US1500per ha per

year)


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a matter of survival...

ecosystem services

the value of these ecosystem services is usually

grossly undervalued by policy decision

nutrient cyclingservices estimated to be inthe order of US $17 x 1012 annually !!!

$17,000,000,000,000!

1997 estimates of the worth of all services

provided by the ecosystem were

33 trillion dollars per year!!!


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What does biodiversity actually do?

biological diversity allows the different ecosystem

functions to be carried out

the primary ecosystem functions are to

Capture

Store

Transfer

Energy

Carbon dioxide

NutrientsWater


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ECOSYSTEMS

ecosystems are a network of

interactions, beginning with

the PRIMARY PRODUCERS

(the PLANTS) and

connecting to herbivores,carnivores, parasites,

decomposers

...energy, nutrients & water

are cycled through thenetwork by these different

groups


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butmany different species are involved in theseecosystem activities

for example

thousands of different species of plant are able to

photosynthesize and capture carbon dioxide,

produce carbohydrates, store them etc.

for example

many species are able to fix nitrogen from the

atmosphere and store it

acacias (wattles), peas, blue-green algae, bacteria


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for example:

many species are involved in decomposition of plantand animal parts and the re-cyclingof nutrients,

carbon dioxide and water

microfauna, fungi, bacteria, larger herbivores &carnivores consumption defaecation

decomposition nutrients

do we really need all these different species

(biodiversity) ?

arent some species more important than

others?


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Are some species more important than others?

species differ in their ecological role

species differ in capacity to adapt to environmental

change

species differ in some aspects of their importance

in their community

in conservation, several categories of importance

are used

indicator species

keystone species

umbrella species

flagship species

New (2000) pages

83-89


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Keystone Species

keystone-nesswas only originally proposed as a

metaphorfor characterizing predators which havea large impact on other (vaguely specified) species

the key stonewas the

single stone which held

the arch-stones in place


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Keystone Species

= species which affect the organization of thecommunity to a far greater degree than one would

predict from the number of individuals or biomass

= most obvious keystone species are top order

predators often important in controllingherbivore populations

eg. grey wolves decline deer populations

explode habitat overgrazed herbaceous

species lost loss detrimental to deer, otherherbivores, insects reduced plant cover soil

erosion further plant loss


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it is simplisticas it views ecosystem interactions

as hierarchicalrather than a webof interrelations

it ignores the role of redundant or

substitutable or back-up speciesin ecosystem

reliability

it has an image problemas keystone species are

often the large top order carnivores (where is the

lowly keystone fungus ??)

it takes little account of the right of individual

species to exist


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what happens to the rest of the ecosystem

if we concentrate our conservation efforts

only on keystone species ???conservation

success ?

an implication of the keystone concept is

that species are either keystone or they are

not a dichotomy not supported in nature


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Umbrella Species

species which can provide

shelter for many others

need not be common or

dominanteg. Eucalyptus camaldulensis

River Red Gum - provides

habitat for numerous

inconspicuous invertebratespecies, birds, other plants etc.


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Flagship Species

species which have

general public appeal -attention grabbing

species

strong emotional

appeal

eg. Eltham Copper Butterfly

Paralucia pyrodiscus lucida or the

Helmeted Honeyeater- used to

gather urgent public support for

immediate identified needs


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Indicator Species

eg. Sooty OwlTyto tenebricosusconsistently

recorded from Mountain Ash forests in Victoria

dependent on arboreal marsupialsand nesting and

roosting sites in maturetrees managementindicator species of forestry practices (which lead

to an abundance of younger regenerating stands of

Mountain Ash, unsuitable for a range of other

species)

species which can be used to

measure, monitor or indicate

some aspect of environmental

change

changes in abundance

loss from local areas


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species grouped according to their

ecological function

one way of examining biodiversity, and what the

range of organisims does, is to put them into

functional groups

functional groups contain species which carry out

similar activities functionally similar taxa or

functional analogues

for example:kangaroo, wombat, sheep, cow, deer, alpacca,

rabbit - are all functionally similar

all consumers of plant material all graze

all herbivores


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ECOSYSTEMS

ecosystems are a network of

interactions, beginning with

the PRIMARY PRODUCERS

(the PLANTS) and

connecting to herbivores,

carnivores, parasites,

decomposers

...energy, nutrients & waterare cycled through the

network by these different

groups

different functional groups


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an example of similar function

nitrogen is the only nutrient which does not

derive from the weathering of rock a

biologicalnutrient

nitrogen gas from the atmosphere must be

fixedinto a form available to plants

170 megatons fixedby biological organisms

20 megatons fixedby lightening


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in ecosystems with high species diversity,

ecosystem processes are much less

sensitiveto variations in that diversity

variations in diversity can arise fromnatural , cyclic processes seasonal,

diurnal, disturbances such as fire

or from extinctionsof species


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Fire

nitrogen lost as vapour (gas)

germination & growth of nitrogen-

fixing species eg. Acacia, Allocasuarina,

the Fabaceae(peas)

nitrogen fixation high

nitrate levels rise and post-fire species

(Acacia, Allocasuarina, peas) eventuallydie

nitrogen persistence now depends on

species which conserve and re-cycle it


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nitrate levels in the soil fall and fixation isresumed by symbiotic or free-living bacteria

nitrogen can be transported in water or

eroded by wind or consumed by herbivores or

by predators

net result is a pool of nitrogen held within

plants, fungi, soil organisms, invertebrate

animals(a highly diverse set of species)


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high species redundancy(= high biodiversity) should

be valued as a critical featureof ecosystems

high diversity must be conservedif ecosystems are to

function reliably

high biodiversity = high reliability of

ecosystem services


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