16. Deforestation, Aforestation and agricultre Flashcards
What is the world cover for trees?
30%
What is the forest cover in the UK
13%
Why are trees important for ecology?
important for rich life and stream nutrients
What is CWD
Coarse woody debris
What is LWD
Large woody debris
What impacts do fallen trees have on a stream
protects bank erosion, gravel traps, refuge, habitat, temperature stabilisation, shading, fish spawning
What is Obligate WD
Only found on wood in streams
WHat us Facultative
Found on other substrates as well as WD
What is the problem with too much logs in the stream system?
Log jams, but not too much of a barrier
What is the best gravels for salmonids
open gravels
Which is the worst fines to have in the river?
<0.84mm
What was the main cause of straighenting on the willamtte river?
river logging
What happens due to increased timber harvesting
added light pollution on streams, nutrient leached from soils, greater development of phytobenthos, algae, greater densities of invertebrates
What do sediments to the gravels in the streams
reduce permeability of the gravel, reduces salmon survival rate
What animals might favour the introduction of sediment?
some worms fly larvae
What is slash
woody debris that provides habitat
How far from the bank is the most profitable trees from the bank
30m
What is a method to manage tree loss
leaving a 30 meter buffer zone
What is afforestation
planting forests
Why is forests normally planted
for commercial use
what are common species for afforestation
sitka spruce
What percentage of the uk forest cover is commercial
12.9%
What is the first stage for aforestation
ground preparation, building roads, making areas for growing, felling of other trees
What are the issues with ground preparation
come back tp this
What is the second stage of comercial AF
Closure of canopy,
What is the problem with the second stage of AF
interception of wet and dry deposition, exclusion of light, reduced summer temperatures raised winter temperatures, reduced primary productivity
What is the 3rd stage of AF
Felling and logging
What can people do to stop acidification to streams?
Avoid planting conifers
What is the main mining near rivers
gold and silver mining north america, coal mining and quarrying
What happens with the channles during mining
movig the channel away from the mine, sediments enter the stream
What minerals are common in tailings
zinc see slide
What are the major mining impacts
heavy metals, chlorides, ferric hydroxide, fine sediments, smothers stream bed
What ancient woodland do we have in the uk?
2.3%
what happens mostly during deforestation
all trees gone, clear felling
what is yarding?
Dragging poles to the centre of the felling site
what does yarding create
sediments washed into rivers, ground disturbance, water runoff
what temperature reigmes can we expect with less trees?
Colder in winter, warmer in summer
What happens to the colour of the water after felling?
Increased turbidity
What happens to slash in water?
decays and uses up oxygen
What is the relationship between salmon and large woody debris?
The more debris the more salmon
Where does the main source of the LWD come from
Within 30m of rivers on either side
What does a 30m buffer zone prevent?
Slash debris, unwanted sediments
which country protects own forest and imports wood?
Japan
What is pressed disturbance
long and happens over time
What mining process is the main release of chlorides
coal
What is a settling pond
Area to store tailings after mining use
What are gravels important for?
Fish spawning areas, insects
What happens when we allow light into a system
Added nutrients, greater amounts of invertebrates, can be deadly though as unbalanced river
Where there is an increase in algae biomass what do we see with fish?
Increase of fry
What happens to stream flows if we remove forest cover?
More extreme flies, evapotranspiraton
What does warm water lead to
Less oxygen
When does permeability become lost?
When fines equal 15-20%
What chemical impact can stage 1 afforestation be?
Nutrient leaching, herbicides
What is ferric hydroxides?
Produced by iron mining?
How can material be seperated out after mining
Settling ponds
