Climate Ecology:

The Study of Sun, Rain, Life, & Place

Plus an aside on wind & water…

Recall the underlying principle thatinsolation-intensity is largely a function of latitude…

…but remember that, for purposes of climate, the “solar equator” moves with the seasons…

…and so does the rain!(Uh, I’ll spend a lot of class-time talking about this diagram.)

This should make you think about the geographical location of major habitat-types

Ecologists think of the Earth as divided into biomes.

• A biome is a big piece of real estate having its own characteristic weather, climate, flora, and fauna.

• Biomes are often named.– This tree, for example, is in the

Seasonal Tropical Forest Biome.

• We’ll briefly honor oceanic biomes and then consider terrestrial biomes in more detail.

As we name & define, remember to keep asking yourself:

“In what ways are biomes models?”

Oceanic Biomes• Oceans dominate the

surface-area of Earth.

• Water evaporated from them (and carried by oceans of air) is the source of all rain, all fresh water.

• Interacting with sun & air, oceans create climates.

• Oceans provide the major proportion of people’s animal-protein foods.

• Many important aspects of ocean-biology are insufficiently understood:

– Oceanic biodiversity…

– Role in carbon-cycles …

– Role in feeding the world…

– Sustainability of current human impacts….

People exploit diverse oceanic biomes in diverse ways.

• This won’t be a major course theme, but:

• Oceans are important in our species-history:– First, seashores & estuaries…– Then continental shelves, then open

oceans…– …food, migration, commerce….

• Until recently, most people assumed that oceanic resources were inexhaustible.

Terrestrial biomes: the world we inhabit

• The diversity of terrestrial biomes is mediated by latitude, altitude, proximity to oceans, and soil-types.

• The most important of these can be integrated into axes of temperature and moisture (next slide).

• People spread across most habitable biomes in < 40,000yrs.

• Human residence is becoming increasingly concentrated; human impact is becoming increasingly widespread.

Summary graph of terrestrial biomes

• Axes of heat and moisture roughly define the structure of the land-biotic world.

• The names are not standardized, but if you learn these, you’ll recognize the others.

• Next slide, more complex, will show biomes’ approximate geographical locations.

Very approximate locations of terrestrial biomes

• Biomes interdigitate; biomes are patchy; biomes change over time.

• See Google’s maps for more accurate (& enlargeable) locations.

• Next slide shows a simplistic model of biome-locations in the tropics.

Note the overall complexity!

Tropical biomes

• Locations of tropical biomes are controlled mostly by convective rain.

• Convective rainfall is largely a function of latitude, proximity to oceans (theoretically, more on east coasts), and mountain ranges.

Tropical Rainforest(to be extensively considered later)

• Typically equatorial.• Not strongly seasonal:

– Most months potentially rainy (> 10cm); total rainfall perhaps 2m/year.

– Daily lows and highs perhaps 28-30oC.

• Ecosystems:– Nutrients “invested” in biomass rather than

“banked” in soil.– Energy fixation very high but production

usually low.– Low species density, high species diversity.– Many complex interactions.

• Human economies are typically low-density or unsustainable.

Seasonal Tropical Forest• Poleward of rainforest (10o-20o).

• Strongly seasonal:

– Seasonality defined by rainfall.

– “Winters” dry; “summers” wet.

– Typically 1.2-1.8m rain/year.

• Ecosystems:

– Soils variable but many nutrients “invested” in biomass.

– Production can be high.

– Some trees respond to predictable seasonality by losing leaves.

– Species less diverse (but perhaps denser) than in rainforest.

• Human economies rely on seasonal agriculture or degrade by too-dense animal husbandry.

Tropical Savanna

• Poleward of seasonal tropical forest (often 15o-25o).• Intensity of seasonality not always predictable:

– Seasonality defined more by rainfall, less by temperature.

– Nights in mid-dry season cool (<20oC); late dry often hot (>35oC).

– Intensity (and even occurrence) of wet season unpredictable.

• Ecosystems (think unpredictability of good times):– Soils vary; often nutrient-rich; productivity typically high.

– Biomass dominated by plants that can respond to good times.

• Human economies dominated by animal husbandry (over-grazing).

A little more about tropical savannasThink rainfall, edaphic conditions, and unpredictability.Grasses can be short (15cm), moderate (1m) or tall (2m).Tropical savannas are occasionally named for emergent vegetation:

AcaciaPinePalm

Thorn scrub

• Between tropical savanna & desert (c. 25o).• Climate is predictably dry (10-75cm rain); fire is typically

excluded; “winter” nights cool; “summer” days up to 40oC.• Ecosystems dominated by species adapted for predictably

dry conditions; responder-plants absent or localized.• Human systems dominated by animal husbandry, poverty.

(Thorn scrub often results from overgrazing of savanna; overgrazing of thorn scrub can lead to desertification.)

Desert• Desert locations typically @

c. 30o and/or mid-continental.• Seasonality is in temperature;

rainfall predictably < c. 15cm; rare rain has dramatic effects.

• Ecosystems:– Edaphic factors almost

irrelevant; production low.

– Biomass structure variable.

– Organisms adapted to absence of water (& often to heat).

• Human economies formerly involved hunter-gatherers or nomadic herders—always at low densities.

Transitional (“Mediterranean”)

climates

• “Mediterranean” regions lie beyond the margins of the tropics and are not always classified as biomes.

• Rainfall is not abundant; summers are usually dry.

• Consider southern European countries, southern South Africa, parts of California….

• Traditional human economies included arboculture and animal husbandry.

Temperate biomes:Is this the world in which

we live?

• Temperate biomes show high diversity (uh, human and otherwise).

• South-temperate & mid-temperate areas are capable of very high agricultural productivity.– Soils often “bank” nutrients, which

farmers have failed to conserve.

• Human cultures in temperate biomes have often held political domination over tropical cultures (see GG&S!).– Tropical cultures have often benefitted.

– But the relationship has almost always worked to the advantage of the temperate cultures.

– Folks, it ain’t been just, it’s seldom been pretty, and U.Meths should be appalled.

• (For convenience we’ll include far-north biomes in this overall category.)

Mixed temperate hardwoods

• This is the biome most familiar to most of us.

• Seasonality is dominated by temperature.

• Ecosystems are diverse forests, many of which were converted to row-crop agriculture and then often to cities, industry, & suburbs.

Temperate grasslands• Characterized by hot/cold

seasons and 20-30cm of sporadic rain, this biome was once dominated by responder-grasses and large, nomadic grazers.

• Subjected to increasing human exploitation, this biome:– is, in its original condition,

almost extinct,

– feeds much of the world with its exotic grasses (wheat & maize),

– is currently dominated by irrigation agriculture that may not be sustainable.

Northern conifer (boreal) forests

• This biome, concentrated in Canada and Siberia, is characterized by cool/cold seasonality; precipitation is often snow. Vast stands of shortleaf evergreens are broken by highly productive small ponds and meadows.

• Human economies are largely extractive (hunting, then some lumbering; increasingly, petro/ mineral resources).

• The global importance of this sparsely-settled biome is not completely understood.

Tundra • As in boreal forests, seasonality is cool/cold, but precipitation is usually less and is predominantly snow.

• Except for forest enclaves in the south, responder grasses and sedges dominate; chief consumer exploitation is by seasonal rodents and migratory artiodactyls.

• Human economies have always operated at very low densities.– Hunters and nomadic herders

– Explorers and petro/mineral extractors.

• Underlying permafrost makes heat-generating engineering activities problematic.

Cold mountains• This biome may be hot to

cold in summer; winters are bitter-cold.

• Air-uplift slopes create monsoon forests on seaward side; inland sides are almost always rain-shadow deserts.

• Human economies, always low-density, include hunting and other extractive activities.

• Increasing subsistence agriculture leads to erosion and severe firewood shortages.

“Human ecology” within wooden walls

On 21 October 1805 Britain secured the seas from Napoleon’s grasp. How?

HMS Victory• To deploy, on orders,

to any deep-ocean place on earth

• To remain at sea for up to 4 years

• To remain independent of land for up to 4 months

• To fling half a ton of iron per minute (at best), accurately, at targets up to half a mile away

The Things She Carried

• Gunpowder: 35 tons• Guns: 104 (largest 3.5

tons)• Shot: 120 tons• Water: 300 tons• Stores: 250 tons• Rigging rope: 26 miles• Pulley blocks: 768• Sails: Enough to cover all

Main’s floor space plus roof (heaviest 815 lbs.)

• Living animals (fewer as the voyage continued)

• Crew

The crew• At full strength: 850• Highly diverse

– 22-24 nationalities

– > 10 languages

• Collectively, skilled at– Sails & rigging

– Navigation

– Gunnery

– Personnel management

– Admiralty law

– Signaling & commo

– Carpentry & repair

– Medicine and surgery

– Law enforcement

– “Housekeeping”

Considerations of size

• Living-working area about 1/6 of Old Main’s floor space (remember: crew of 850).

• “Bedrooms” 5’6” X 18” X 18”.

10,000+ years of maritime engineering:

• The ship had to be constructed to withstand six potentially simultaneous sources of stress:– Water pressure

– Load-bearing

– Sea-working

– Wind-sail impulse

– Artillery recoil

– Battle damage

Natural Resources Required (timber)• 2000 mature oak trees

(that’s about 100 acres—or about one “old Wofford,” denuded):

• Some could be plank-sawed, but others were made into “non-joinable” structures.

• Trees were specially selected & were cut 14 years before construction began.

• Timbers have lasted well!

Navigation• Maps and charts• Sextants (several!)• Compass (two official)• Celestial charts• Chronometers (two official; rich

captains had another; HMS Beagle, of Darwin-fame, was a charting vessel and carried twenty-two chronometers); can’t know longitude w/o knowing precise time!

• Knowledge of spherical trigonometry (& eventually of calculus) was required.Senior Non-Com: Thomas

Atkinson, Sailing Master