Test 1.3 Ecosystem Engineers

Question 1

Ecosystem Engineers

Answer 1

Organisms that modify, maintain and create habitats

Question 2

Allogenic Engineers

Answer 2

Change the environment by “transforming living or non-living materials from one physical state to another, via mechanical or other means”

Question 3

Autogenic Engineers

Answer 3

Change the environment via their own physical structures i.e. their living and dead tissues. Other organisms live in or on them

Question 4

Beaver; Allogenic or Autogenic Engineer?

Answer 4

Allogenic; Cuts down trees, modify river flows by building dams. Hunted to extinction in UK around 16th century. Common in Scandinavia & NA.

Question 5

What are the effects of beaver built dams?

Answer 5

Create complex diverse habitat for other organisms

Question 6

Crested Porcupine; Allogenic or Autogenic Engineer?

Answer 6

Allogenic; Dig holes to feed on roots leaving behind habitats for seeds & plants to get caught & grow in

Question 7

Shelter-Building Caterpillers; Allogenic or Autogenic Engineer?

Answer 7

Allogenic; Construct leaf roles & tents. Hide from predators

Question 8

European Wood Ants; Allogenic or Autogenic Engineer?

Answer 8

Allogenic; Build mounds to house colonies that are preferred by earth worms

Question 9

Woodpeckers, Bee-eaters; Allogenic or Autogenic Engineer?

Answer 9

Allogenic; Create holes other species then occupy. Holes are a scarce resource therefore they can control the density of birds in tree landscapes

Question 10

Subterranean herbivorous mammals; Allogenic or Autogenic Engineer?

Answer 10

Allogenic; Alter the environment by digging

Question 11

Pocket Gopher; Allogenic or Autogenic Engineer?

Answer 11

Allogenic; Mean soil moved: 17.8m^3 ha^-1 yr^-1. Burrows underlay 7.5% of ground. Mounds cover 5-8% of an area; 30-50% over course of a year

Question 12

What are the effects of pocket gophers on soil structure & movement?

Answer 12

Soil in backfilled burrows is 15% less compact than undisturbed soil matrix. Mounds have low bulk density (10-40% lower than underlying soil)

Mounds increase mean height and variation of land

Creates a “mammalated microtopography”

Question 13

How do gophers affect erosion?

Answer 13

Gophers speed up the down-slope creek of soil

Question 14

How do gophers affect soil transport on a shallow gradient?

Answer 14

Increase transport of soil simply by digging and moving the ground

Question 15

How do gophers affect soil transport on a steeper gradient?

Answer 15

They reduce amount of transport by building terraces

Question 16

How do gophers affect plants?

Answer 16

Mounds smother plants

Create space for colonist seeds

Increase seed mortality

Question 17

What is a competition-induced wave of biomass?

Answer 17

An increase in biomass in the immediate surrounding area of the mound / burrow due to no use of nutrients & water on the actual mound. More for the surrounding plants.