Lecture 11 - sustainable forestry Flashcards
how much habitable land area is forest?
37%
what forest types have high biomass e.g high amounts of carbon stored in trees?
tropical rainforests
what is a global tree restoration potential?
- Because of the quantity of carbon stored in trees they could become part of the solution to get carbon back out of the atmosphere and back into biomass
- however there are lots of threats on tree stocks
what threatens trees?
- wood products
- fuel e.g. Africa and Asia are big contributors - huge numbers of poor people that live around tropical forests etc and they are extremely reliant on wood as primary source for heating and cooking - also has issues for pollution e.g. smoke particles etc
what is the problem with trying to reduce wood use for fuels?
- Question is how we help these poor people by providing alternative technologies which allow them to reduce the requirement to chop down trees
describe carbon storage in boreal forests
- Stores a lot of carbon in both the forest and the soil - actually more than tropical forests however most in soil not trees
what type of mycorrhiza are found in boreal trees?
- Ectomycorrhiza- found in only 3% of plant species, but these plants are exceptionally important dominant components of some forest ecosystems
- Ectomycorrhiza may be important assisting global soil C sequestration particularly in the boreal forest
where are the highest carbon storage areas found?
peats -where Sphagnum mosses rather than trees are normally dominant
describe the root systems of plants which have ectomycorrhiza
- HUGE AMOUNTS OF FUNGI ON THE ROOTS - therefore root systems tend to be smaller as they invest so much in the mycorrhizal hyphae
Ectomycorrhiza: >95% of root tips of pine, spruce and fir trees are sheathed by fungus - what does this mean?
- These roots have no physical contact with soil
- Virtually all plant nutrient and water uptake is through fungus
- Almost all organic carbon released from living roots passes to the fungi
PROVIDE CRITICAL INTERFACE BETWEEN TREE AND SOIL
Difference between Arbuscular mycorrhiza and EM?
-The enzymes they maintain
what do EM extracellular enzymes do?
- Ectomycorrhizal fungi produce a range of extracellular enzymes that are involved in the hydrolysis of organic C, N and P containing components of litter, and C- containing structural components of plant litter
- Actively involved in decomposing organic matter to a certain degree and releasing nutrients preferentially from that
describe nitrogen cycling in EM
- EM is able to develop a short circuit where it takes up organic nitrogen bypassing other microorganisms and fauna
- Selective depletion of easily altered N by ectomycorrhiza restricts access to N by saprotrophs thereby inhibiting both N and C mineralisation- minimising N losses from these plant guilds
- Very efficient mycorrhiza
why is the plant species diversity low in boreal regions?
because the trees can compete with herbaceous plants that don’t have the ability to tap into organic nitrogen stores so just rely on mineral nitrogen pools- high dominance by these trees
what do ectomycorrhiza also allow trees to gain access too which most other plants cant do?
aluminium phosphate -
how do EM trees deal with tannins?
adapted ways of coping with soils litters rich in tannins and ways they can recycle nutrients from within this - some EM actually produce enzymes that can partially degrade tannins
what is a big threat to boreal forests?
- The northern hemisphere boreal forest and tundra are experiencing the greatest rates of warming and models suggest they will to continue to do so
- Big temp changes in boreal regions compared to global averages
- Potential threats to soil C stocks and increased risks of forest fires
- Burning is becoming quite a big issue in terms of loss from these regions
7 common threats to boreal forests
1) Logging
2) Fire
3) Pine beetle - transmits infection to the trees - abundance is rising with temp increases
4) Climate change/global warming
5) Increasing co2 emissions from wildfires - a lot of these fires are cause by humans
6) Temperate forest losses are increasing
7) Forest fires often generate extra lightning storms from the upwelling heat, smoke and water vapour - one big fire can cause multiple fires in a cascade of effects
2 consequences of fires 1= positive 1= negative
- Post fire soil erosion and degradation
- Can generate charcoal which could be stabilised in the soil and potentially contribute to long term carbon stocks
why is replanting after logging not a quick solution?
- Even after replanting it takes nearly 80 years to recover biomass and carbon stocks in the soil back to the same point
describe an additional problem of oil palm trees compared to other agricultural trees
- Oil palm is particularly damaging compared to other agricultural trees in terms of erosion
what is agroforestry?
a way of sustaining food production and soil ecosystem services
- Range of different types of agroforestry systems e.g. field margin trees
To try and meet climate change projections, how many trees do we need to plant?
1.5 billion
describe how the UK is doing for meeting climate change projections in terms of trees?
- Tree planting has actually decreased in England
- Some of England power stations are actually run by wood not coal - we are actually importing this from north America
