Lecture 6

Question 1

NPP?

Answer 1

Net primary production of Carbon (temperature and water influence it). amount of carbon fixed per year minus the amount that is oxidized during cellular respiration. It can be estimated by above ground biomass (biomass of living plants excluding roots)

More NPP means more food for top carnivores (it’s the baseline for how much food energy is available in an ecosystem)

–>Net Primary Productivity

Question 2

Fixed Carbon

Answer 2

provides energy for organism but is not used for growth (not used for the production of of biomass)

Question 3

Biomass

Answer 3

products from living organisms or recently living organisms

Question 4

soils

Answer 4

a complex mix of living and non-living material on which terrestrial life depends

Question 5

what conditions maximize photosynthesis and plant growth

Answer 5

when temperatures are warm and conditions are wet (and limited by drought and cold)

Question 6

biomes

Answer 6

groupings of plants and animals communities (based on dominant veg’n type and distinctive abiotic conditions

abiotic conditions control species distributions (e.g. you don’t find cacti in rain forests)

Question 7

Describe Tropical Wet Forests

Answer 7

• aka rain forests
• found in equatorial regions
• high temperature and precipitation
  
  • precipitation exceeds 100 mm during most months
• low variability
• No seasons (plants grow all year long, high NPP,)
• highest biodiversity
• deep organic soils

Question 8

subtropical deserts

Answer 8

-30 degrees in latitude away from the equator both N and S
-temperature: variable, never below freezing
-precipitation: very low, limits productivity, intense competition for moisture, low soil building (bc rapid decomposition and low productivity), sand and stone
2 ways to adapt:
1) grow at low rate year-long (cactus), OR
2) be dormant, and break out of dormancy rapidly when there is rainfall (short reproductive stages) e.g. desert shrub called ocotillo

-in graph when you scale it so 10 deg celcius=20mm prec, the temperature graph is above prec (showing that the area is dry)

Question 9

Temperate grassland

Answer 9

• aka prairies or steppes
• across NA (close to west), and heartland of Eurasia
• precipitation: low (but greater than deserts)
  
  • too dry for trees
• Temperature: moderate, too cold and seasonal for drought-adapted desert species
• variability: plant growth based on seasons (no growth during winters bc very cold) -summers: very hot
• forests which burn converted to grassland
• productivity: less than forests. highly fertile soils (agriculture), nutrients remain in soils (bc low rainfalls)

Question 10

Temperate forests

Answer 10

• precipitation: high, consistent, fire less common, trees can dominate
• temperature: variable w/ season, drops below 0 where plants go dormant
• vegetation: deciduous trees in N America and Europe, Broad-leaved evergreens in New Zealand and Chile
• biodiversity: moderate

Question 11

Boreal forests

Answer 11

• aka Taiga
• Canada, Alaska, Russia, N Europe
• Temperature: very cold winters (dormancy), cool short summers (rapid growth)
• precipitation: similar to grassland (low)
  
  • BUT: moist (bc of evaporation is low)
• vegetation: evergreens, and cold tolerant conifers (begin photosynthesizing early in spring, deciduous trees are disadvantaged bc low N in soil and leaves need N)
• biodiversity: low

Question 12

Arctic Tundra

Answer 12

• from poles to subarctic
• sunlight: variable highly!
• temperature: cold (below freezing), growing seasons only 6-8 weeks, permafrost soils
• precipitation: low (lower than desert), soil is saturated all year (bc low evaporation)
• trees: too dry and too cold for trees (shrubs are common)
• biodiversity: low
• productivity: low and low decomp (vs. high decomp in deserts)
• above ground biomass: low