Test 3 - WEEK 10 - Engineers and Succession

Question 1

Ecosystem engineers

Answer 1

• organism that modify, maintain and create habitats
• They change biotic and abiotic materials that directly or indirectly affects the availability of resources to other species

Question 2

Allogenic engineers

Answer 2

Change the environment by ‘transforming living or non-living materials from one physical state to another

Question 3

Autogenic engineers

Answer 3

Change the environment via their own physical structures. other organisms live in or on them

Question 4

Name and explain 4 allogenic engineers

Answer 4

Beaver - build dams altering distribution of reptiles, amphibians, invertebrates and trees
Crested Porcupine - creates soil pits while foraging what are rich in organic matter
Shelter-building caterpillars - construct leaf-rolls, ties, folds and tents
European wood ants - build mounds to house their colonies that are preferred by earthworms
Woodpeckers, bee-eaters - create holes other species occupy

Question 5

Pocket Gopher - Ecological characteristics

Answer 5

• Feed on plant roots

- Western Salsify: 25% root loss has a greater effect than 75% leaf

Question 6

Pocket Gopher - tunnels

Answer 6

• Excavate tunnels horizontally and depth of max root density
• Soil from tunnels deposited on surface creating mounds or used to backfill tunnels
• 360-3400 more energy used digging then walking space

Question 7

Pocket Gopher - Effect

Answer 7

• Backfilled oil is 15% less compact so collapse occurs

- Mounds have low bulk density so particles erode leaving stones and larger particles

Question 8

How do gophers increase soil erosion

Answer 8

Speed up down-slope creep erosion

Question 9

Pocket gopher - Effect on plants

Answer 9

• Mounds smother plants creating gaps
• Create space for colonists, enhance germination
• Increase seed mortality
• Persistent individuals are larger

Question 10

How far away from disturbance does plant biomass increase

Answer 10

10cm away

Question 11

Name the plant that prefers disturbed patches

Answer 11

Monkey Flower

Question 12

What has happened to the redwood forest over the last 200 years

Answer 12

96% has been logged

Question 13

How do redwood trees facilitate colonization

Answer 13

• by providing a structure
• trees, shrubs and ferns grown on redwoods, up to 98m above ground
• plant seeds and fungi create plant community on redwood

Question 14

what creates a canopy soil

Answer 14

foliage