Exam 2 - Habitat Threats

Question 1

What is the primary land use that leads to habitat degradation?

Answer 1

Agriculture

Crop use intensity usually dictates the impacts on biodiversity

Question 2

Grasslands

Answer 2

Mainly lost to agriculture and urbanization

Question 3

Define habitat fragmentation

Answer 3

The breakage of habitat into smaller pieces.

1. reduction of area
2. reconfiguration into smaller pieces

*can be caused by humans or naturally

Question 4

Natural disturbances create __________

Answer 4

heterogeneity

Question 5

Habitat patchiness leads to differences in species ________ and __________ at several ________ and ________ scales.

Answer 5

abundance and distribution

spatial and temporal scales

Question 6

Define edge effects

Answer 6

influences created at the boundary between habitats. Found on habitat patch

Question 7

Define metapopulations

Answer 7

Species that occur as sets of local populations spatially isolated, but connected via occasional dispersal

Question 8

What are the three meta population dynamics?

Answer 8

1. population source - a net surplus of new individuals
2. population sink - a net loss of individuals
3. population stable - no net change

Question 9

List 4 biological consequences of fragmentation

Answer 9

1. Initial exclusion - immediate, direct loss of species
2. Crowding effect (lifeboat) - individuals crowding into the remaining habitat
3. Insularization and area effects - to become island-like, isolated, and regulated to habitat islands
4. edge effects * - habitat size and shape matter. An irregular strip or a smaller patch will have worse edge effects than a large squared patch

others:

5. Matrix effects - not able or willing to move among habitat species because of the poor habitat between patches
6. Invasive species effect - fragmentation creates new or makes old ecological niches making is easier for invasive species to colonize areas

Question 10

Define wetlands and their threats

Answer 10

Wetlands are transitional areas between terrestrial and aquatic systems,

Loss, pollution (toxin and eutrophication), alteration of hydrological regimes, and invasive species are major threats.

Question 11

What are the threats to rivers

Answer 11

Impoundments contribute to endangerment of 91% of fish and 99% of mussels. Threatened by agriculture, siltation and pollution.

Question 12

How much and why has KY lost its wetlands?

Answer 12

about 3/4

The unsustainable withdrawal of water for agricultural use has led to this shrinkage.

Question 13

Define eutrophication

Answer 13

the accumulation of excessive nutrients, particularly nitrates and phosphates from fertilizers and sewage, in aquatic systems that leads to explosive growth of phytoplankton.

-can lead to hypoxic “dead zones”

Question 14

Define habitat shredding

Answer 14

fragmentation that leaves long, linear pieces or “shreds”

Question 15

Define habitat tentacle

Answer 15

small branches of intact habitat attached to habitat shreds

Question 16

Shreds can offer more habitat connectivity than patches but…

Answer 16

if the shreds are too narrow, then edge effects can render it unusable.

Question 17

List 3 general species vulnerable to fragmentation

Answer 17

1. wide-ranging
2. nonvagile (poor dispersers)
3. habitat specialists

others:

4. large patch/interior requirements
5. low fecundity/recruitment
6. low tolerance to humans

Question 18

What are some strategies of species for coping with habitat fragmentation (3)?

Answer 18

1. persist or thrive in human-altered habitat patches
2. take advantage of reduced competition or predation (or increased resources)
3. be mobile. dispersers typical do better

Question 19

what are 3 strategies for maintaining biodiversity in fragmented landscapes?

Answer 19

1. minimize edge effects
2. understand the value of matrix and find ways to enhance its value
3. identify critical movements (ex. migration routes)

Question 20

What are 3 other major causes of habitat loss and degradation?

Answer 20

1. light poluttion
2. noise pollution
3. toxins (ex. heavy metals)

others:

4. chemical spills and dumping
5. endocrine distrupting compounds (EDC)
6. air pollution