Biol 302 Nutrient Cycling1 COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302.

Biol 302 Nutrient Cycling 1

COMMUNITY AND COMMUNITY AND ECOSYSTEM BIOLOGYECOSYSTEM BIOLOGY

Biology 302Biology 302


NUTRIENT CYCLINGNUTRIENT CYCLING

READINGS for this lecture series:READINGS for this lecture series:

• KREBS cpt 27. Ecosystem Metabolism III: Nutrient Cycles

• KREBS cpt 28. Ecosystem Health:

Human Impacts; Pp 590 - 600


NUTRIENT CYCLINGNUTRIENT CYCLING

• We are not dealing with:

• Energy – eventually gets “lost”

• We are dealing with:

• Nutrients – these cycle


Aldo Leopold “A Sand County Almanac”Aldo Leopold “A Sand County Almanac”“The Journey of Atom X”




Thanks for buying my text book




1. Biochemical cycles:• Redistribution within an individual organism• This really is r- and K-selection from first term

2. Biogeochemical cycles:• Exchange within an ecosystem

• N, P - rapid exchange• Ca - long if stored in long-lived tree tissue

3. Geochemical cycles:

• Exchange of chemicals between ecosystems• Nutrients and dust• CO2, SO2, NOx














Krebs Fig. 27.12; p573

SULPHUR CYCLE



NITROGEN CYCLE



WATER CYCLE



CARBON CYCLE


These figures have:

• All sorts of rates of transfer

• We can compare between systems


These figures have:

• All sorts of rates of transfer

• We can compare between systems

More interesting:

• What influences the rates?

• What are the impacts of altering the rates?


1. Biochemical cycle

2. Biogeochemical cycles:

• Exchange within an ecosystem



BIOGEOCHEMICAL CYCLES: A few major points (general principles): 1. Nutrient cycling is never perfect i.e.

always losses from system• input and output

• Precipitation • Runoff & stream flow

• Particle fallout from atmosphere • Wind loss

• Weathering of substrate • Leaching

• Fertilizer & pollution • Harvesting


3. Relatively 'tight' cycling is the norm

2. Inputs and outputs are small in comparison to amounts held in biomass and recycled

4. Disturbances (e.g. deforestation) often uncouples cycling

5. Gradient from poles to tropics


Annual Nitrogen budget for the undisturbed Hubbard Brook Experimental Forest. Values

are Kg, or Kg/ha/yr






Biol 302 Nutrient Cycling 24Krebs Fig. 27.7; p567

Stream water nitrate concentrations from Hubbard Brook watersheds, NH


Concentrations of ions in streamwater from experimentally deforested, and control, catchments at Hubbard Brook.


Disturbances (e.g. deforestation) often uncouples cycling, and a consequent:

loss of nutrients (Krebs p567 (Fig 27.7)) x13 normal loss in Hubbard Brook (become Atom X's)

reduction in leaf area 40% more runoff (would have transpired) more leaching more erosion, and soil loss

decouples within-system cycling of decomposition and plant uptake processes all the activities (and products) of spring decomposition get

washed away







5. Patterns from:

POLAR TROPICS

Decomposition Slow Rapid

Proportion nutrients in living biomass

Low (mostly (OM)

High

Cycling Slow Rapid


Relative proportion of Nitrogen in organic matter components

ROOTS


Relative proportion of Nitrogen in organic matter components

SHOOTS


DECOMPOSITIONIF SLOW:

• Nutrients removed from circulation for long periods

• Productivity reduced

• Excessive accumulations have impact on soil

IF TOO FAST:

• Nutrient depletion

• Poor chemistry and physics of soil such as soil fertility, soil moisture and resistance to erosion


RATE OF DECOMPOSITION• humid tropical forests about 2 - 3 weeks• temperate hardwood forests 1 - 3

years• temperate / boreal forests 4 - 30 yr• Arctic/Alpine / dryland forests >40 years

• generally, rate of decomposition increases with increase amount of litterfallResidence time … the time required for the

complete breakdown of one year’s litter fall






Decomposition Rates influenced by:• temperature• moisture• pH, O2

• quality of litter• soil type (influences bugs)• soil animals• type of fauna / flora

• rapid if bacterial• slow if fungal






Plant species

% weight loss in 1

year

C/N ratio

# bacterial colonies

#

fungal colonies

Bact / Fungi ratio

Mulberry 90 25

Redbud 70 26

White Oak 55 34

Loblolly pine

40 43

Relationship between rate of litter decomposition Relationship between rate of litter decomposition and the balance between bacteria and fungiand the balance between bacteria and fungi






(J) J A S O N D J F M A

100

90

80

70

60

50

40

30

20

10

0

% leaf litter

remaining

0.5 mm mesh bags

7.0 mm mesh bags






Plant species

% weight loss in 1

year

C/N ratio

# bacterial colonies

#

fungal colonies

Bact / Fungi ratio

Mulberry 90 25 698 2650 264

Redbud 70 26 286 1870 148

White Oak 55 34 32 1880 17

Loblolly pine

40 43 15 360 42

Relationship between rate of litter decomposition Relationship between rate of litter decomposition and the balance between bacteria and fungiand the balance between bacteria and fungi


WHAT DETERMINES THE TYPE OF, AND ABUNDANCE OF, MICROFLORA / FAUNA IN THE FIRST PLACE? activities of soil fauna e.g. earthworms species of plant producing the litter chemical composition of the litter

C/N ratio - high gives poor decomposition microbes need N to use C N often complexed with nasties (tannin)

optimum is 25:1

Douglas fir wood 548:1 Douglas fir needles 58:1 alfalfa hay 18:1

pH of litter and therefore of the forest floor more acid promotes fungi, less bacteria

moisture and temperature


1. Biochemical cycle

2. Biogeochemical cycles


• exchange between ecosystems

• examples: carbon and sulphur


CARBON CYCLINGCARBON CYCLING(Krebs p590-600)

CO2 is in the atmosphere at 0.03%

99% locked up in coal, oil, limestone, chalk etc.

Human activity produces about 5-10% of natural emissions mostly due to fossil fuels before industrial revolution 280ppm currently about 355ppm projected to be 700ppm by 2100 (unless rather

profound change to human activities)



US Energy Information Admin forecast that world emissions will increase by 54% above 1990 levels by 2015, or x2 CO2 in about 40 years (2030)

Canada produces only 2% of global greenhouse emissions (but with 0.5% of world’s population)

From 1960–1990, Canadian emissions increased by 250%

These GCM (General Circulation Models) predict x2 CO2 =

increase 1.3 to 4.5C



Next Fig.



Concentration of CO2 emissions in Hawaii





1. Lead to +3C at equator, and +5-8C at poles

a 0.6C increase in world temperatures since 1900

2nd warmest year historically was 1997; warmest was 1998

ice shelf is melting faster than predicted in Antarctica

retreat of glaciers worldwide

N-ward movement of permafrost in the Mackenzie River Basin

Biol 302 Nutrient Cycling 56Krebs Fig. 28;14; p597

The Greenhouse Effect of CO2 and other trace gases


An estimate of temperature variations over last 400000 years, obtained by comparing O2 isotope ratios in fossils taken from ocean cores in the Caribbean. Dashed line is the ratio from 10000 years ago.

CLIMATE HAS ALWAYS CHANGED!

400300200100


Next Fig.

Average temperature 1902-1980


Average temperature 1902-1980

Next Fig.



Estimated mean global surface temperatures, 1860 – 1990, relative to 1940

1940



2. +25cm sea level

already rising along the Gulf states

Louisiana losing approx. 40 ha of coastal wetland per day!

15 of the world’s largest cities

(London, New Orleans, Cairo, NY, LA)

300m people will be displaced

Fiji, Tahiti, Bangladesh (disappear in the next 100 years)







3. +25-50% dry matter production

agriculture zones

population zones

most of prairies and Gt. Plains become desert

reserves and parks (1 C can shift 60-100 miles)



4. Plant and animal responses (Krebs pp593-596)

INDIVIDUAL PLANT RESPONSES (p593)

i. increased plant growth

x2 CO2 leads to 40% increase growth in some trees

ii. increased water use efficiency

iii. Increased reproductive output (fruit, seed etc.)

IV. influence migration rates



4. Plant and animal responses

PLANT COMMUNITY RESPONSES (p594)

i. Increased evaporation in the arctic tundra

lose much fish habitat , and migratory birds

ii. Release of enormous C-reserves from boreal forests

iii. Other effects may be quite minimal


Rat

e

Temperature

Photosynthesis

Respiration

12

3

1. Boreal forests

2. Temperate forests

3. Tropical forests


Rat

e

Temperature

Photosynthesis

Respiration

12

3

1. Boreal forests

2. Temperate forests

3. Tropical forests1 – 2.8% increased death rate during

El Nino events


4. Plant and animal responses

INDIVIDUAL ANIMAL RESPONSES

i. Migration vertically becomes a problem

leads to local extinction


TWO PROBLEMS: rate of change is unprecedented and may be too fast for adaptation major impact will come from extreme events

heat waves and floods prob. that a heat wave of >5 days at >35C in Washington D.C. will rise from 17% to 47% with an increase of 3C

prob. of drought in mid-West will increase – 1988, 1993, 1994 more rainfall in India (good), but more flooding in Bangladesh longer hurricane season Boreal forest are vast store houses of carbon

fires give off carbon earlier and drier summers give 50% more fires

20% of excess CO2 in atmosphere is from forest burning 178000 Amazon fires >1 km2


WEIRD WEATHER

(MacLean's, Jan 1999)

1996

Floods in the Saguenay region

10 dead, 2000 displaced from homes

Vancouver's snowfall of the century

1997

Devastating floods in Manitoba; Red River

28000 people displaced from homes


1998 Ice storm in Quebec and Eastern Ontario (storm of the century) China’s floods - Yangtze River burst its banks The hottest year on record, worldwide (after '97, 94, 89) A 200,000 ha fire in Florida - worst ever Heat wave in the southern US:

Temperatures over 38OC for over 2 weeks Killed over 100 people

Heat wave in India killed 2500 and spawned raging bushfires in Australia

Hurricane Mitch most devastating hurricane in 200 years killed an estimated 11000

In US Midwest - spate of tornadoes killed 129


1999

The Ontario snow storm

In the state of Maine a record low of - 48OC


CENTER FOR CLIMATE MODELING (Environment Canada, Victoria) violent winter storms will increase from 1 every 20 years to 1

every 10 years in Canada’s north, extreme daily max. temperatures will peak at

10OC above present Record rain and snow storms will deliver 10% more ppt.

and become more frequent “Vancouver’s famous drizzle” will become “frequent torrential

downpours” “Blizzards in the east will last longer and dump more snow”

more avalanches more spring flooding

“Toronto’s Storm of ‘99, like Montreal’s Ice Storm of the Century and Winnipeg’s Great Flood, could well turn out to be a mere

overture to the far greater wrath of the weather to come”


U.S. NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION:

Number of heat waves 3 days has increased 88% between 1949 and 1995

Extreme snow and rainstorms increased 20% since 1900


1. CLIMATIC "REALITIES"

The greenhouse effect - real on a planetary scale

Temperature - CO2 correlations - real in earth's

history

Atmospheric build-up of radiatively active gases - real within human observation


U.S. Scientists' report doesn’t support the Kyoto treaty(Wall St. Journal November 2001)

Last week the U.S. National Academy of Sciences released a report on climate change, prepared in response to a request from the White House, that was depicted in the press as an implicit endorsement of the Kyoto Protocol. CNN's Michelle Mitchell was typical of the coverage when she declared that the report represented “a unanimous decision that global warming is real, is getting worse, and is due to man. There is no wriggle room.”


As one of 11 scientist who prepared the report, I can state that this is simply untrue.

The full report makes clear that there is no consensus, unanimous or otherwise, about long-term climate trends and what causes them.

But - and I cannot stress this enough - we are not in a position to confidently attribute past climate change to carbon dioxide or to forecast what the climate will be in the future.


One reason for this uncertainty is that, as the report states, the climate is always changing; change is the norm. Two centuries ago, much of the Northern Hemisphere was emerging from a little ice age. A millennium ago, during the Middle Ages, the same region was in a warm period. Thirty years ago, we were concerned with global cooling.

Richard S. Lindzen Professor of MeteorologyMITMember of National Acad. Sciences panel on climate change.


2. WHAT CAN THE MODELS TELL US?

GCM's tend to agree on the big picture

1.3 to 4.5C for x2 of CO2

BUT resolution is poor

they disagree at regional and local levels

they grossly oversimplify clouds and oceans

So, there is much uncertainty and ample room for doubt and scepticism


3. THE CLIMATIC FUTURE

some sort of climate change is inevitable

increased frequency of extreme events and greater variability are probable

general warming is probably, but not certain

convincing observation are present

credible models years away


SULFUR CYCLE(Krebs p572-576)

Considerable exchange between oceans and atmosphere mostly in the form of SO2 and H2S

Humans produce 160% of natural production SO2 emitted by plants, seawater, volcanoes

combustion of fossil fuels and organic matter H2S anaerobic decomposition

H2S is oxidized to SO2

SO2 combines with atomic O and molecular O2, and ozone O3

to produce SO3

SO2 + H2O = H2SO3 (sulphurous acid)

SO3 + H2O = H2SO4 (sulphuric acid)

NOx + H2O = HNO3 (nitric acid)

NOx can destroy ozone



Emissions of SO2, NOx, and volatile organic compounds (e.g.. Methane) in USA.



ACID RAIN: Horrible topic - much ambiguity

by definition, rain with pH<5.6 'normal' rain is slightly acidic (carbonic acid) pH 2.7 is common in Pennsylvania; a storm

in West Virginia had 1.5 pH




Normal range of pecip.



Acidity of precipitation over Canada and US in 1982; changed little in past 2 decades


In 1979 acid rain was described by the Federal Environment Minster (Canada) as “the most serious and pressing environmental problem Canada has ever faced.”

Early evidence - absence of lichens on trees on buildings (Parliament House in Ottawa,

Taj Mahal, Capitol Bldg., Acropolis) more insidious - effects on rivers, lakes and forests some lakes in the Adirondacks

drop of 2pH units in 30 years i.e. x100! 180 lakes are fishless



estimated that 150,000 lakes of 700,000 in eastern Canada have been damaged

about 14,000 are believed to be acidified (i.e. losing normal life)

140 Ontario lakes are fishless

Nova Scotia, salmon disappearing from streams

In the Czech Republic nearly 60% of the forests ddamaged or destroyed

In US, some high elevation spruce forests (Shenandoah and Gt. Smoky Mt) have been affected.



Effects of acidification on eastern Canadian Lakes


Catch of (percentage of average for 1936-1940) Atlantic salmon in Nova Scotia streams 1935 - 1980

pH >5

pH < 5


PANTHER LAKE

SAGAMORE LAKE

WOODS LAKE

One Rain –

Three lakes in the

Adirondaks


0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Mean for Adirondak Lakes 1995 1930s


0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Small mouth bass

Lake trout

Brook trout

Yellow perch

Salamander

Mayfly

Whirligig

Water boatman

Mean for Adirondak Lakes 1995 1930s


Forests in Czech Republic, killed

by acid rain


but… damages cuticle (Black Forest) interferes with guard cells disturbs metabolism and poisoning of cells accelerates foliar leaching alteration of N-fixation and mycorrhizal fungi increased susceptibility to other stresses but … organic forest floor is well buffered but accelerates leaching of Ca (the buffer) leads to mobilization of Al

toxic to fine roots leads to a reduction in growth or die back (Black Forest)


ALSO READ p12 of web hand out:ALSO READ p12 of web hand out:

• effects of acid depositioneffects of acid deposition

• effects of ozone depletioneffects of ozone depletion

Biol 302 Nutrient Cycling1 COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302.

Documents

nutrient cycling8 slide

nutrient cycling5 slide

nutrient cycling17

nutrient cycling18

nutrient cycling11

nutrient cycling12

nutrient cycling21

nutrient cycling19