Test 2.3 Deforestation, Afforestation, Mining and Agriculture

Question 1

Why is wood important In rivers?

Answer 1

Wooded debris: source of food

Structure for habitat

Question 2

Meaning of CWD & LWD

Answer 2

Coarse wooded debris

Large wooded debris

Question 3

Importance of CWD & LWD

Answer 3

LWD contributes to heterogeneity (diversity) of habitat: riffles, runs, pools

• Traps gravel- especially important for fish spawning
• Protects banks from debris
• Provides habitat for macroinvertebrates
• Stabilizes flows- evapotranspiration
• Stabilises temperature regimes

Question 4

Importance of riparian vegetation in terms of LWD

Answer 4

Provides cover and produces leaf litter CPOM - food for fish

Question 5

What is ideal about salmonid spawning gravels?

Answer 5

• Ideal habitat: coarse gravel with little ‘matrix’ of fine sediments
- Allows flow of clean, well-aerated water for egg development
• Problem if excessive amounts of ‘fines’
- Especially <0.84mm
- Clogs gravels & reduces flow and DO

Question 6

What is the effect on light due to timber harvesting on streams?

Answer 6

• Light levels & nutrients

• Opening up canopy increases light
• Nutrients leached from soils
• Greater development of phytobenthos (algae)
• Greater densities of invertebrates – food for juvenile salmon:

Question 7

What is the effect on stream flows due to timber harvesting on streams?

Answer 7

• Less evapotranspiration
• Increased flood events
• Lower base flows

Question 8

What is the effect on temperature due to timber harvesting on streams?

Answer 8

• Greater variability in temperature

Question 9

What is the effect on fine sediment harvesting on streams?

Answer 9

• Clogging of interstital spaces / under stones bad for some mayflies; caddisflies; stoneflies
• May favour burrowing forms: some worms, fly larvae
• Algae on stone surfaces reduced (smothered

Question 10

Best management practices of streams:

Answer 10

• Leave a buffer strip of 30m either side of rivers
• Manage drainage patterns
- Prevent runoff of fine sediments
- Slash debris

Question 11

Best management practices in mining operations

Answer 11

• Use settling ponds- trap & remove sediments
• Re-contour streams
• Remove tailings
• Replant with natural vegetation

Question 12

Name forms of organic wastes

Answer 12

• Manures: direct or sprayed onto fields
• Slurry & washings from buildings
• Milk and dairy washings
• Silage liquors

Question 13

What % of the world do forests cover?

Answer 13

30%

Question 14

What % of the UK do forests cover?

Answer 14

13%

-2.3% ‘ancient’ but not post ice-age ‘old growth’ forest

Question 15

Meaning of Obligate wood species

Meaning of Facultative wood species

Answer 15

Obligate: Only found on wood in streams- e.g. Chironomidae

Facultative: May be found on other substrates

Question 16

How are old growth forest river streams important for fish (salmon) species?

Answer 16

LWD streams provide habitat for all stages of life cycle:

Deep pools

Refuges under logs for adults

Clean gravels trapped by woody debris for spawning

Rich food resource and cover for young fry fish

Question 17

Why are salmonid spawning gravels an ideal habitat

Answer 17

Allows flow of clean, well-aerated water for egg development

Problems if excessive amounts of ‘fines’ (<0.84mm)
-Clogs gravels & reduces flow & DO

Question 18

What is yarding and what are its ecological effects?

Answer 18

The dragging of logs to central area for transport generating disturbance to soils and creates sediment

Disturbance generates disturbance; fine trashy material when wood is sawn

Question 19

Effects of timber harvest on stream channels path?

Answer 19

More simplified river channels: traded & complex to simple single channel system

e.g. Willamette River Oregon

Question 20

Effects of timber harvest on stream light & nutrients?

Answer 20

• Opening up canopy increases light
• Nutrients leached from soils
• Greater development of algae
• Greater densities of invertebrates
• Food for juvenile salmon

Old growth forest: lower algal growth
Clear cut forest: highest algal grow
Density of salmon fry strongly correlate with algal biomass

Question 21

Effect of timber harvest on stream flows

Answer 21

• Less evaporations-transpiration
• More rapid runoff
• Increased flood events
• Lower base flows

Question 22

Effects of timber harvest on temperature

Answer 22

-Greater variability in temperature due to reduced shading

• Increased summer temperatures (heat/DO stress)
• Greater algal production

-Extreme winter cold temperaturesger

Question 23

How does amount of fine sediment affect permeability & oxygen?

Answer 23

As the amount of fine sediment (<0.88mm) amongst the gravel particles increases - the permeability (allowing oxygen flow) declines rapidly

Question 24

How does fine sediment affect invertebrates?

Answer 24

Clogging of interstitial spaces / under stones: bad for some mayflies, caddisflies, stoneflies

May favour burrowing forms. Some worms, fly larvae

Algae on stone surfaces reduced (smothered)- fewer grazers

Question 25

How does turbidity affect invertebrates?

Answer 25

Reduced light penetration Algae on stone surfaces reduced >> fewer grazers

Question 26

Meaning of 'Slash'

Answer 26

Woody debris especially in small streams -Decays & uses up oxygen May change hydrology & ecology

Question 27

What is the most valuable part of the forest with respect to the stream?

Answer 27

The riparian zone 30m from the bank 40% of woody debris comes from first meters away from stream

Question 28

How can timber harvest be managed better? (Ecologically with fish communities in mind)

Answer 28

Leave 30m riparian zone untouched Manage drainage patterns - prevent runoff of fine sediments -

Question 29

What is the relationship between Coho salmon and volume of large woody debris?

Answer 29

Positive relationship | More woody debris = better for salmon

Question 30

Describe fish productivity in old growth streams

Answer 30

Lots of CWD LWD provides refuge from fast flows. Good proportion of fish survive the fast flows through to the spring

Question 31

Describe fish productivity in Clear-cut streams

Answer 31

More light due to cut back trees, algal growth, greater density of invertebrates, increase in number of young fish. No protection from winter flood flows, a lot wash out and die. Productivity less than old growth forest

Question 32

Describe fish productivity in buffered streams

Answer 32

Happy medium Logs providing refuge: production in spring is higher Light allowed to reach stream; increase in young fish Strip of trees still provides woody debris providing refuge from high flows in winter so fry production in spring is higher

Question 33

Name afforestation common commercial species and their beneficial features

Answer 33

``` Sitka spruce (UK) Monterey Pine (NZ) -Fast growing on nutrient-poor soils (28 years from planting to harvesting) ```

Question 34

Current UK woodland cover

Answer 34

12.9% most of which commercial forest Minimum 5% between WW1 & 2 Big increase in planting post war- Forestry Act Incentive to replace commercial woodland with native species

Question 35

Current NZ % of forest that is commercial

Answer 35

96% - major exporter

Question 36

Three stages of commercial forestry

Answer 36

Ground preparation Closure of canopy Felling

Question 37

What occurs in the Ground Preparation phase of commercial forestry and what are the impacts?

Answer 37

-ploughing, draining, road construction, planting Impacts: - Increased sediment and turbidity- infilling of channels - Increased flows during periods of high rainfall - Leaching of nutrients (& herbicides) from soils

Question 38

What occurs in the Closure of Canopy phase of commercial forestry and what are the impacts?

Answer 38

Rapid, dense growth Impacts: - Interception of wet and dry deposition; acidification - Exclusion of light - Reduced summer temps; raised winter temps - Reduced primary productivity - Reduced macro invertebrate abuncance - Study in Scotland showed 15% reduction in trout growth in afforested streams

Question 39

What occurs in the Felling/Logging phase of commercial forestry and what are the impacts?

Answer 39

Similar effects to removal of old-growth forests but not as marked Impacts: - Altered flow regimes - Increased sedimentation - Acidification - Reduction in light penetration and productivity

Question 40

Best management practices for afforestation

Answer 40

30m riparian vegetation buffer strips Good ditching and interception of runoff Removal of 'slash' from small streams Minimise use of pesticides & nutrient additions

Question 41

Effect of gold mining in Alaska on rivers

Answer 41

Before: Natural braided river Natural riparian zones After: Channel moved Sediments excavated and gravels sorted - washed Huge amounts of sediment generated

Question 42

Impacts of left tailings (abandoned gravel heaps) on rivers

Answer 42

Leach heavy metals: As, Al, Zn, Pb, Cu, Hg - Toxic effects - Example of 'press' disturbance

Question 43

Mining impacts

Answer 43

``` Heavy metals Chlorides Ferric hydroxide - smothers substrate Impacts on algae, invertebrates, spawning ```

Question 44

Best management practices in maintaining rivers affected by mining operations

Answer 44

Using settling ponds- trap & remove sediment Re-contour streams Remove tailings Replant with natural vegetation

Question 45

What are some common practices and characteristics of agricultural activities?

Answer 45

- Removal of natural vegetation - Altered hydrology - Reduced inputs of natural organic material - Increased erosion 'poaching' - sediments e.g. potato turning - Livestock manures - Artificial fertilisers

Question 46

Name dominant forms of pollution in agricultural activities

Answer 46

Farm wastes Nitrates Pesticides Sediments

Question 47

How do pollutants from farmlands reach rivers?

Answer 47

Wash in directly Leach through soils Manure spread on ground- wash into rivers Animals may have direct access to rivers

Question 48

Name forms of organic wastes

Answer 48

- Manures - Slurry & building washings - Milk & dairy - Silage liquors

Question 49

What pollutants have the lowest Biological Oxygen Demand (BOD) in order in mg l-1?

Answer 49

Clean river water <5mg l-1 Treated sewage ~20mg l-1 Untreated sewage ~300mgl-1 Dilute dairy parlour & year washings 1000-5000 mg l-1 Liquid effluents draining slurry stores 1000-12,000 mg l-1 Cattle slurry 10,000-20,000 mg l-1 Pig slurry 20,000-30,000 mg l-1 Silage effluents 30,000-80,000 mg l-1 Milk 80,000-120,000 mg l-1

Question 50

What are the % sources of N in rivers?

Answer 50

Agricultural land 60% Sewage treatment works 35% Other land 5%

Question 51

What are the % losses of N in crops?

Answer 51

Potatoes 100% OSR 70% Peas 70% Beans 60%

Question 52

Impacts of nutrients (increased N & K)

Answer 52

Eutrophication - Rapid plant growth - Death & decay - Microbes use up O2 ^Increases turbidity: even more reduced light

Question 53

How does increasing nutrients effect the vegetation in a stream?

Answer 53

With increasing levels of nutrients there tends to be a move from rivers dominated by macrophytes (rooted) to algae

Question 54

Impacts of herbicides and insecticides

Answer 54

Herbicides - weed control in crops Insecticides - Crop pests - Livestock treatment for worms - Sheep dipping for ectoparasites Impacts: - Death of natural plants; invertebrates; fish - Potential increase in more tolerant organisms

Question 55

Best management practices to protect water courses from agricultural activities

Answer 55

``` Decrease ploughing in autumn Delay ploughing in crop residue (winter stubble) Sow autumn crops early Sow cover crops in winter Carefule storage of farm wastes Decrease amounts of fertiliser, manure & sewage applied Leave minimum 10m buffer zone Fence off livestock ```