Nutrient cycling

Question 1

Describe the movement of matter through an ecosystem

Answer 1

Closed system

Mater moves within global + local cycles BUT is not added from outside the system

Matter moves between abiotic + biotic states

Question 2

Describe the biogeochemical cycles within ecosystems

Answer 2

Exchange from ocean to atmosphere = relatively fast

Exchange from mantle to lithosphere = relatively slow

Rate of exchange between pools depends on types of biota

Question 3

What are the human impacts on water cycle?

Answer 3

> over-abstraction from lakes + rivers
> vegetation loss
> soil erosion 
> pollution of surface water + ground aquifers
> drainage of wetlands
> climate impacts

Question 4

What does the tracking of C show?

Answer 4

The movement of energy

Question 5

How is C fixed into the organic pool?

How is CO2 released into the atmosphere?

Answer 5

Photosynthesis

Respiration

Question 6

What are the human impacts on the C cycle?

Answer 6

Burning fossil fuels
Reducing photosynthetic material
Farming systems

Question 7

How is N made bioavailable?

Answer 7

Bacterial fixation
Lightning
Burning

Question 8

What are the human impacts on the N cycle?

Answer 8

Eutrophication

- increases PP but has -ve effects throughout ecosystem (species loss, changes in community structure + toxicity)

Question 9

What are the features of the P cycle?

Answer 9

None in atmosphere

Binds w/ soil + has highly localised movement

Main source = rocks of maritime origin

Question 10

What are the human impacts on the P cycle?

Answer 10

Livestock waste
+ P used in inorganic fertiliser
-> eutrophication
= dead zones

Over-harvesting crops
= removes P from topsoil

Question 11

What are the 3 steps of decomposition?

What does the rate of decomposition depend on?

Answer 11

Leaching
Partitioning
Micro-partitioning

Temp
Precipitation
Groups of orgs within ecosystem

Question 12

What are the effects of decomposition on the community?

Answer 12

Fast decomposition
-> less litter
= faster turnaround

Question 13

How does deforestation affect nutrient cycling?

Answer 13

Increased volume of water runoff

-> Amount of N run off increased greatly

Question 14

What are the ways ecosystems can be disturbed?

Answer 14

Deforestation
Mining
Fire

Question 15

How can fire benefit an ecosystem?

Answer 15

Germination of some seeds
Regeneration of nutrients locked in biomass
Control of insect pests

Question 16

What are the effects of fire on nutrient cycling?

Answer 16

Loss of nutrients (N + C)

Transfer of nutrients to ash

Warmer soil profiles alter microbial growth + decomposition rates

Question 17

What are the 2 major strategies of restoration ecology?

Answer 17

Bioremediation

Augmentation of ecosystem processes

Question 18

What is bioremediation?

Answer 18

Using orgs to detoxify ecosystems

• absorb + concentrate toxic compounds facilitating removal from environment
• sometimes metabolise toxic molecules into inorganic or non-toxic

Question 19

What is biological augmentation?

Answer 19

Using orgs to add essential materials to degraded ecosystem

e.g.. N-fixing bacteria to increase available N in the soil
or
Mycorrhizal fungi to help plants access nutrients