Ecology and Ecosystems

Study of how organisms interact with their environment

Living community + nonliving environment, linked by energy flow and nutrient cycling

The parts: species, biomass, soil, canopy layers

The processes: energy flow, nutrient cycling, productivity, decomposition

Nonliving: light, temperature, water, soil, nutrients

Living: plants, animals, microbes, and their interactions

Sunlight, temperature, rain, soil texture, wind

Competition, herbivory, mycorrhizae, decomposers, predators

Group that can interbreed

One species in one area

All the living populations in an area

Community = living only. Ecosystem = living + nonliving + energy and nutrient flows

Gradual change in an abiotic factor across space

West-to-east rainfall drop, elevation, coast-to-inland, latitude

Urban-to-rural, nitrogen deposition, pollution, roads and fragmentation, logging, light and noise

Weather = short-term. Climate = long-term average (about 30 years)

Macro (regional), meso (landscape), micro (local, like under a canopy)

Pacific Ocean, Cascades and Olympics, westerly winds, mid-latitude position

Mild wet winters, warm dry summers

West: mild, wet, small temperature range. East: extreme temperatures, dry

High on west side, sharp drop east of the Cascades

Seasonal swings get bigger going east

Air rises up windward side, cools, rains. Descends leeward side, warms, dries

Wet

Dry

Rising air expands and cools (about 6.5 C per km). Sun distance barely matters

No. More reflected, less absorbed, less heat

Max water vapor air can hold at a given temperature. Rises with temperature

Saturation vapor pressure minus actual vapor pressure. High VPD = dry air, stomata close

Low in winter, highest in summer

The energy input. About 30% reflected, rest absorbed then re-emitted as longwave

Tropics (direct sun)

Poles (low sun angle, high albedo)

Surplus at the equator, deficit at the poles. Heat moves poleward

Mild wet winters allow evergreen photosynthesis. Dry summers hurt deciduous broadleaves

Dry summers, cool dark winters

Summer drought, cool winters, low winter light, poor soils, snow at elevation

Regional climate, parent material, topography

Microclimate, microsite soil, local disturbance, biotic interactions

Evergreen needles, lots of leaf area, strong tracheid wood, thick bark and resin, water stored in sapwood [CHECK]

Winter photosynthesis, drought-tolerant needles, nutrients kept in long-lived needles, shed snow

Long growing season, abundant winter water, large leaf area, long lifespans

Photosynthesize all year, resist water loss, shed snow, keep nutrients

Peaks in summer, stops in winter

Continues through mild winter, slows in dry summer [CHECK]

More water, longer growing season, milder temperatures, less fire

False. West has more total biomass [CHECK]

West is much higher. East is limited by water

More negative (gravity + longer path), so less photosynthesis

Makes its own food (photosynthesis)

Eats other organisms for energy

Producers, primary consumers, secondary consumers, tertiary consumers. About 10% energy passes up each level

Light level where photosynthesis = respiration

Light level where more light no longer helps

Low compensation point, low saturation point, low max rate

High compensation point, high saturation point, high max rate

Light is absorbed layer by layer, creating canopy layers. Shade-tolerant species stay low

Flat leaves and branches, larger and thinner leaves, more chlorophyll, low respiration

Flat (shade) leaves have low cost [CHECK]

Positive, then levels off. N is in Rubisco and chlorophyll

Avoids winter, cheap leaves, high photosynthesis rate

Rebuild leaves yearly, short growing season

Photosynthesize any warm period, conserve nutrients

Costly leaves, lower rate, winter damage risk

Light, temperature, CO2, water, nutrients (N), VPD

Enzyme-driven: slow when cold, peaks at optimum, drops when hot

Sun leaves: small, thick. Shade leaves: large, thin

6 CO2 + 6 H2O + light -> C6H12O6 + 6 O2

NPP = GPP - autotrophic respiration

Carbon gained per water lost

Waxy cuticle, sunken stomata, small leaves, stomatal closure, deep roots, mycorrhizae

Removes CO2 from air

Returns CO2 to air

N, P, K

C, H, O (from CO2 and water) [CHECK]

Roots absorb dissolved ions, helped by mycorrhizae

Nitrogen [CHECK]

Phosphorus [CHECK]

Prevent erosion and compaction, riparian buffers, limit fertilizer [CHECK]

Better structure, water holding, nutrients, microbial food, less erosion

Billions of bacteria per gram, plus many fungi [CHECK]

Soil around roots. Lots of microbes, key for nutrient uptake

Climate, Organisms, Relief, Parent material, Time

Largest (0.05-2 mm)

Medium (0.002-0.05 mm)

Smallest (under 0.002 mm)

Clay

Water held in small pores, plant-available

Water left after gravity drainage

All pores full of water

Surface organic layer (litter)

Dark mineral topsoil with organic matter

Pale leached layer (clay and iron washed out)

Unweathered solid rock

Squeezes pores. High compaction = shallow roots [CHECK]

Temperature, moisture, litter quality, clay, oxygen, disturbance. Lasts years to millennia

Gaseous and sedimentary

C, N, O

Matter is conserved: inputs - outputs = change in storage

Deposition, N fixation, weathering, CO2 uptake

Leaching, erosion, gas emissions, fire, harvest

Watershed (water carries elements, outputs measurable at stream) [CHECK]

Photosynthesis (GPP) - respiration = NPP. Litter to soil, decomposers return CO2

Burning fossil fuels (very small change) [CHECK]

Humans use large share of NPP. N and P boundaries exceeded [CHECK]