lsm2251-12 global ecology

8/3/2019 LSM2251-12 Global Ecology

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LSM 2251

Lecture 13Glo bal Eco logy


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Summary of Lecture 12:

1. A landscape is a heterogeneous area consisting ofdistinct patches

2. Patches or landscape elements are distinct, relativelyhomogenous areas.

3. Usually applied at the human scale , although the scale ofthe organism(s) of interest may be more appropriate.

4. Landscapes can be described by the types, sizes,shapes, numbers and positions of the patches.

5. Patchiness can arise from the physical environment or the

action of landscape engineers , but most studiedexamples are a result of human impacts .6. The most connected landscape element is the matrix .7. Understanding and managing landscapes often involves

consideration of connectivity .


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A regionalscale isparticularly

appropriate forlooking atproblems likecarbonemissions andthe extinction ofspecies.


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A regionalscale isparticularly

appropriate forlooking atproblems likecarbonemissions andthe extinction ofspecies.

But this regionis connected toall the otherson Earth.


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This is a new perspective,first seen by human eyesin the 1960s


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Reading :

Molles - Chapter 23Smith & Smith - Chapter 29

[For more detail on plate tectonics, climate and sea-levelchanges, and human impacts in SE Asia see The Ecology of Tropical East Asia , Chapter 1.]

Definitions:

Biosphere- the global sum of all ecosystems. Wikipedia- the thin layer about Earth in which all living organisms exist.Smith & Smith- the sum of living organisms


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How are species, communities, ecosystems and

landscapes connected at the global scale?

1. They share the same planetary history .

2. They share one atmosphere .3. The share one ocean .

4. They are connected by the movements of people

5. .. and other organisms .


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How are species, communities, ecosystems and

landscapes connected at the global scale?


This includes gradual changes over millions to billionsof years

plate tectonicsoscillations in the Earth s orbit

Global catastrophesextraterrestrial impacts rare but devastatingsupervolcanoes more common


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Different arrangementsof continents have ahuge influence on global

climate, sea-level, bioticconnectivity etc.


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Our region has beenassembled like agiant jigsaw puzzle

over 400 millionyears.


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Indonesia has more active volcanoes than any other countryin the world as a result of the continued collision with the

Australia- India plate. The Sunda megathrust.


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Mt Merapi in Java last year.


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The same processwas responsible forthe devastating 2004Indian Ocean Tsunami


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and the one off Sumatra on October 25th


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The gradual cooling of the Earth s climate over the last 70million years has been largely as a result of changes in theconcentration of greenhouse gases and in the arrangementof continents.

t e m p e r a t u r e

R b A R hd /Gl b l W i A


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Robert A.Rohde/Global Warming Art


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On a shorter time scale: regularoscillations in the Earth s orbit result inchanges in the amount and distribution ofsolar radiation reaching the Earth ssurface. This in turn was the main driver ofthe ice ages over the last 2 million years.


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Globaltemperature


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65 m years ago,the impact of a10-km diameterasteroid killedevery animal on

Earth bigger thana cat (+ numeroussmaller, aquaticand plant species)

800 000


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800,000 yearsago, a low-angleimpact innorthern SE Asiafrom a comet orasteroid,probably > 1 kmdiameter,

sprayed tektites(glass) fromAustralia toChina. Theregional andglobal impact isunclear and noimpact craterhas been found

yet!

?


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The Toba super-eruption in Sumatra74,000 years ago probably thebiggest eruption in

2 million years -may have cooledthe Earth by asmuch as 10 oC,although this isdisputed.


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ENSO index above the line, El Nio, below La Nia

El Nio-Southern Oscillation (ENSO)a fluctuation between unusually warm (El Nio)

and unusually cold (La Nia) sea surfacetemperatures in the tropical Pacific Oceanin association with changes in the atmosphericpressure pattern (the Southern Oscillation)related to the strength of Pacific trade winds .


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In an El Nio year, sea surface temperatures are warmer thanusual in the eastern and central Pacific. [i.e., the western Pacificwarm pool shifts east]

In a La Nia year, sea surface temperatures are cooler than usualin the eastern and central Pacific.


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Sea-surface temperatures during El Nino and normal conditions


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Sea-surface temperatures last week (from the NOAA web site),

i.e., the eastern Pacific is still cooler than usual.


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Fires in Sumatra & Borneo

cause haze in Singapore


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The ENSO cycle is responsible for much of the

interannual variation in the Earth s climate, and thus inecosystems, e.g.

Strong El Nios bring droughts to much of SE Asia ,resulting in mass flowering in rainforests across theregion + forest fires and resulting haze in Singapore.

El Nios reduce nutrient-rich upwelling off the west coastof South America , reducing marine productivity and

causing a failure of the sardine fishery, deaths and failureto reproduce in seabirds and fur seals, etc.

El Nios in South Australia result in droughts that reducered kangaroo populations.


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Strong La Nias bring floods to eastern Australia and parts of

SE Asia


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Some atmospheric pollutants (e.g. particulates) have only a localor regional impact, but long-lived pollutants accumulate in theatmosphere and have a global impact.


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[This graph extends the record back from gas bubbles in polar ice]


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Fossil fuels are the major source of CO2 emissions, but c. 15%of the global total comes from land-use changes particularlydeforestation making Indonesia the world s third largest

source of CO2 emissions, after China and the USA.


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Trends in the major greenhouse gases (from NOAA website)


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Greenhouse gas greenhouse impacts (from the NOAA website):the total impact has increased by 30% in your life-time!

carbon dioxide

methane

nitrous oxideCFC12


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This shows the dramatic rise in China s carbon emissions over the last 30 years and the increasing importance of India.


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China

Europe

USA


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Emissions per person is a fairer way of comparing countries.Singapore would be red on this map, although the Governmentdisputes this, arguing that it is unfair to include shipping and oilrefining. But if every country excludes major parts of itseconomy, then every country has low emissions!


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But China, and particularly India, still have low emissions perperson. Singapore s per capita emissions are 10 -15 million

metric tons of CO2, if shipping is excluded.


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But different sources give different numbers. If all Singapore semissions are included, with no exceptions, then per capitaemissions may be as high as 27.9 tons, which is higher than

the USA or any country in Europe.

[Singapore]


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[Singapore]

G h Eff


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Greenhouse Effect


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Temperature projections for SE Asia (including Singapore)

over the next century. From IPCC 2007.


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The most recent 2100 projection from the UK s Hadley Centre.

Singapore s NCCS is assuming 2.7 4.2 oC higher than today.


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Latest predictions from the UK s HadleyCentre for a business as usual GHGscenario are +5-6 oC for Singapore!

International agreements to control ozone-destroying CFCs worked.C d h f h ?


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Can we do the same for greenhouse gases?


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Trends in the major greenhouse gases (from NOAA website)


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2. They share one atmosphere .

3. They share one ocean , so:

sea-level changes

ENSO and other atmosphere-ocean interactions

global marine pollution

ocean acidification

global overfishing in international waters


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Sea-levels over the last 300,000 years relative to the presentday, caused by fluctuations in the amount of water in ice sheets

(in turn caused by the orbital oscillations mentioned above).

Land exposed by sea-levels 60 and


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120 m below present. Global sea-levelwas at -120 m, 20,000 years ago.


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Predicted sea-level rises over the next century as aresult of global warming range from:

60 cm , if you only consider thermal expansion of theseawater

< 2 m if you allow for the (observed) melting of theicecaps

[to 25 metres if you look at the last time the planet was

that warm, in the early Pliocene, 4-5 million years ago!]


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Ocean acidification: one of the scariest things we are doing to ourplanet! This shows the change over the last c. 200 years.


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Ocean acidification:1. Mean pH has already dropped by nearly 0.1 units as

a result of rising atmospheric CO 2. This is a logscale, so this equates to a 25% increase in acidity .

2. Even if we manage to control CO 2 emissions , pH willdecline by another 0.3-0.5 units by 2100.

3. This will directly impact all organisms with calciumcarbonate skeletons: corals, molluscs, echinoderms,many types of plankton + it is likely to have othereffects. The precise impacts are still being debated.

See the Wikipedia article for an up-to-date summaryof the problem.


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Fishing down the food web, from Wikipedia. This shows (fromleft to right) the impact of progressively severe overfishing.


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2. They share one atmosphere .

3. The share one ocean .

4. They are connected by the movements of people

the initial human expansion out of Africa

prehistoric and historic human migrations

modern human movements


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The green area is that occupied by Homo erectus , 1-2 millionyears ago, while the red shows the spread of Homo sapiens .


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Possible routes by which modernhumans spread through the region


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humans spread through the region50-40,000 years ago. Sea-levelswere 60-120 m below now.

Some large species became extinct and others, such as orangutans and giantpandas, became much more restricted in their distributions .


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Population growth in tropical East Asia over the last 10,000years. After the initial impact of the first human arrivals on anave megafauna, human impacts were relatively mild in most

areas until the 19th

and, particularly, 20th

centuries.

Clidemia hirta , from South America, is an invasive species atBTNR and on Kent Ridge


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Wherever people have travelled, they have deliberately oraccidentally transported other organisms, leading to invasive

species problems and increasing homogenization of global biota.

BTNR and on Kent Ridge.

Scarlet-backed Flowerpecker


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pYellow-vented BulbulBrahminy KiteJavan MynaSwiftletPacific SwallowSpotted DoveBlack-naped OrioleRock PigeonCommon TailorbirdCollared KingfisherCattle Egret

Olive-backed SunbirdSulphur-crested Cockatoo

Alien species now dominatein all non-forest habitats in Singapore.

Of the 33 bird species seen atNUS by LSM3251 students, 9

were introduced alien species,including 5 of the top 14species, and the mostabundant single species inSingapore, the Javan myna

(Summary from Luan Keng)


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In the 1980s, the native green crestedlizard (left) was replaced in open habitatsby the alien changeable lizard (right)


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My FYP student, Cedric Tan, found the alienYellow Crazy Ant in all habitats in Singapore,including primary rainforest at MacRitchie.

Teh Hong YingLee Gang


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Recently, two undergraduateproject students, Lee Gangand Teh Hong Ying, foundthe invasive African big-headed ant , Pheidole megacephala, in Bukit TimahNature Reserve.

Molles gives human


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Nitrogen deposition fromhuman activities: 1960and 2000 (from the

Ecosystems lecture)

Bobbink et al. 2010

impacts on the globalnitrogen cycle as anadditional example of howwe are transforming ourplanet. We now fix more Nthan all natural processestogether.


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The sum of all humanimpacts will be globalclimate change and a

massive loss of globalbiodiversity over the nextcentury.


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My generation messed up the planet (with a lot of help fromour parents). You need to do a better job.

S f L t 12


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Summary of Lecture 12:

Before human impacts:1. Global processes had major impacts on local ecology on

multiple timescales.2. Most interannual variation in climate and ecosystem

processes results from global atmosphere-ocean

interactions, such as ENSO, which cannot be understoodlocally.3. Climatic fluctuations on timescales of 1000s to 100,000s

of years are dominated by the influence of oscillations inthe Earths orbit on the amount and distribution of solarradiation. These in turn influence global sea-levelsthrough changes in ice volume.

4. On even longer timescales, plate tectonics becomes thedominant influence + extraterrestrial impacts etc.


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Think

globally

Actlocally

Environmental Biology Specialization:L l 3000


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Level 3000LSM3252 Evolution and Comparative GenomicsLSM3253 Plant PhysiologyLSM3254 Ecology of Aquatic EnvironmentsLSM3255 Ecology of Terrestrial EnvironmentsLSM3256 Tropical HorticultureLSM3261 Life Form and Function

LSM3262 Environmental Animal PhysiologyLSM3271 Global Change BiologyLevel 4000LSM4253 Behavioural BiologyLSM4254 Principles of Taxonomy and Systematics LSM4261 Marine BiologyLSM4262 Tropical Conservation BiologyLSM4263 Field Studies in Biodiversity

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lsm2251-12 global ecology

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