Biological Resources (A2); Forest Resources (Complete)

Question 1

What percentage of the Earth’s land area do forests cover?

Answer 1

30%

Question 2

What are the features of forests?

Answer 2

-Often climax community in ecological succession
-Found wherever conditions are suitable
-Usually involve presence of soil & climate that doesn’t involve prolonged dry periods/serious lire’s

Question 3

What determines the type of forest found?

Answer 3

Temperature

Question 4

Why are forests important for human survival?

Answer 4

They provide ecological services & resources that we need

Question 5

The importance of forests- resources; how can resources be gained from forests?

Answer 5

-Some are extracted from existing natural forests
-Most are produced by cultivated plantations of species that were discovered in forests

Question 6

The importance of forests- resources; why could the loss of wild forests result in?

Answer 6

Loss of valuable species that become extinct before their importance is understood, or even before they’re been discovered

Question 7

The importance of forests- resources; why is wood important and what kind can be extracted from different forests?

Answer 7

-Is strong, has a high strength: weight ratio, flexibility & requires little processing for use, is often readily available
-Mahogany & teak from tropical forests
-Oak & beech from temperature deciduous forests
-Conifer timber from northern coniferous forests

Question 8

The importance of forests- resources; what are the general uses of wood?

Answer 8

-Structural uses; building construction, telegraph poles, shuttering for concrete structures
-Furniture
-Tools

Question 9

The importance of forests- resources; what are the uses of fibres extracted from different forest elements?

Answer 9

-Most paper is made from flattened sheets of interwoven cellulose fibres from pulped wood
-Cotton is made from fibres that surround seeds of cotton bush
-Viscose (rayon) textiles are made by chemical treatment of cellulose fibres extracted from wood

Question 10

The importance of forests- resources; how is fuel provided by forests and why is this important?

Answer 10

-Fuelwood; before industrial revolution, wood was the main energy resource for almost everyone in the world
-Even though oil,coal, gas now provide more energy than wood, it still provides energy for the greatest number of people, esp LICs

Question 11

The importance of forests- resources; in what different ways can forests provide food?

Answer 11

-Trees provide fodder for live stock & fruit + nuts for human food
-Animals living in forests can provide human food like bushmeat in LEDCs
-Many forest species are crucial in agriculture, eg coffee, cacao, bananas, papayas, Brazil nuts. Pigs & chickens were originally forest animals
-Wild varieties of cultivated species contain genes for new characteristics that maybe important in future selective breeding programmes
-May be many more species in forests that could be cultivated/domesticated

Question 12

The importance of forests- resources; how can forests contribute to new medicines?

Answer 12

-Trees produce many chemicals that have medicinal uses
-Some are still extracted from tree tissues while others were identified in trees but are now synthesised artificially, eg quinine that was originally extracted from the Cinchona tree
-Most forest species haven’t yet been researched for medicinal compounds they may contain

Question 13

The importance of forests- ecosystem services; how do forests contribute to atmospheric regulation?

Answer 13

-Balance of photosynthesis & respiration in forests is important in regulating atmospheric levels of carbon dioxide & oxygen
-Act as huge reservoir of carbon, mainly in carbohydrate cellulose; main component in wood. If it weren’t stored in wood, most would be in the atmosphere as CO². Cellulose is hard to digest so wood is a carbon reservoir w/ relatively long residence time compared w/ carbon in other living material
-Carbon sequestration to counteract global climate change by planting more trees. Photosynthesis also releases O²; essential for aerobic organisms & maintenance of ozone layer

Question 14

The importance of forests- ecosystem services; why is the total mass of carbon in forests/forest soils significant?

Answer 14

-Total mass of carbon in forest soils is greater than in vegetation, especially in boreal forests
-Total mass of carbon in forests is roughly x2 mass in atmosphere

Question 15

The importance of forests- ecosystem services; how do forests aid with the regulation of the hydrological cycle?

Answer 15

-Transpiration rates from forests are greater than from any other terrestrial ecosystem & is important in increasing precipitation rate downwind
-Interception by foliage of forests also increases evaporation rates but decreases infiltration
-Help soil formation & reduce soil erosion so soil depth may be greater than for other ecosystems. Soil will retain water after it has rained & moderate flow of water into rivers

Question 16

The importance of forests- ecosystem services; how do forests absorb sun,ight and why is this important?

Answer 16

-Low albedo of forests increases absorption of sunlight & storage of heat in water in wood
-Forests absorb sunlight during day; much of this is connected to heat which is radiated at night → reduces extremes of temp between day & night

Question 17

The importance of forests- ecosystem services; how do forests influence light absorption and what does this result in?

Answer 17

-Canopy vegetation absorbs a lot of solar insulation, esp red & blue wavelengths that are absorbed by chlorophyll
-Plants living below canopy have access to less light & much of this is green light not effectively absorbed by chlorophyll. So, these plants often have special adaptations like denser chlorophyll, additional pigments or growth periods when trees have lost their leaves

Question 18

The importance of forests- ecosystem services; how do forests influence wind velocity and what does this result in?

Answer 18

Lower wind velocity produced by shelter of trees means plants below canopy layer use animals to help w/ pollination & seed dispersal rather than wind

Question 19

The importance of forests- ecosystem services; how does the humidity in forests influence animals?

Answer 19

High humidity levels = animals like amphibians can survive more easily as skin doesn’t dry out

Question 20

The importance of forests- ecosystem services; what are the reasons for forests being good habitat/wildlife refuges?

Answer 20

-Most diverse terrestrial ecosystems
-Each species of tree supports its own unique community of species so forests w/ greater variety of tree species are likely to have greater overall biodiversity
-Create v diverse habitats w/ large variety of possible ecological niches; increased by stratification within forest which is most obvious in forests w/ highest primary productivity
-Trees create variations in abiotic factors like light levels/wavelengths, humidity, temp, wind velocity

Question 21

The importance of forests- ecosystem services; what does the high primary productivity of forests provide and why is this limited?

Answer 21

-A lot of energy to support higher trophic levels in food chain
-Energy isn’t always available to other organisms quickly, as much is stored in wood; released when tree dies & decomposes

Question 22

The importance of forests- ecosystem services; in what different ways do forests aid soil conservation?

Answer 22

-Dead vegetation contributes humus & nutrients to soil & food energy for detritivores + decomposes that are involved in soil formation
-Trees help to prevent soil being washed/blown away by intercepting rainfall & reducing wind velocity
-Living trees & leaf litter on soil surface help reduce wind velocity & impact of rain drops
-Tree roots help hold soil together → reduces erosion by water running over surface
-Humus from decomposed vegetation binds soil together
-Forest soil w/ lots of organic matter will have lots of living organisms incl worms → increases ease w/ which water infiltrates into soil; reduces runoff & so amount of soil washed away

Question 23

The importance of forests- ecosystem services; how are forests important for recreation/amenity uses?

Answer 23

-Important for recreational uses like walking, orienteering, cycling & camping
-Also important for educational activities

Question 24

Forest exploitation & management; what did traditional forest management include?

Answer 24

-In pre-industrial societies, forests produced wood from wide variety of diff species, each having its own particular uses
-Traditional techniques involved management of existing woodland areas to maximise yields of forest products → rarely involved total removal of natural forest & often retained mixed-species forests w/ trees of diff ages

Question 25

Forest exploitation & management; what are the uses of different tree species?

Answer 25

-Oak; timber-framed buildings, ship buildings -Beech; furniture, tool handles -Ash; furniture, roof timbers -Holly; mathematical instruments, walking sticks -Hazel; fencing panels, interwoven wall panels

Question 26

Forest exploitation & management; what are standard trees?

Answer 26

Trees grown to maturity for production of large timbers for uses like construction of buildings & ships

Question 27

Forest exploitation & management; what does coppicing involve?

Answer 27

-Cutting trees to ground level on cycle of 1-20 years depending on use of wood -Branches that regrow were used for baskets, fencing, charcoal, wall panels & roof

Question 28

Forest exploitation & management; what is pollarding?

Answer 28

Similar to coppicing but trees are cut above ground level so regrowing branches can't be eaten by livestock

Question 29

Forest exploitation & management; how does the demand and uses of timber change as a society develops?

Answer 29

-Demand for wood fuel may decline as people switch to fossil fuels/electricity -Species-specific uses of wood from traditionally managed woodland are often replaced by large-scale uses like chipped wood for sheet construction material & plywood for concrete shuttering -Harvesting methods changed from selective logging/cutting of small areas to large-scale clear-felling; reduces wildlife biodiversity of forest -Existing natural woodland may be replaced w/ plantations of selected species

Question 30

Forest exploitation & management- methods; why are non-indigenous species cultivated?

Answer 30

-Tree species selected for cultivation are often non-indigenous; may be better adapted to environmental conditions & are less likely to suffer damage due to pests/disease -Growing non-indigenous species is less likely to support indigenous wildlife species as their inter-species needs for food, pollination, seed dispersal, habitats are less likely to be met

Question 31

Forest exploitation & management- methods; what are examples of non-indigenous forestry plantations in different places?

Answer 31

-UK; Sitka Spruce & Douglas Fir (originally from N America) -Corsican Pine (originally from S Europe) -Central America; Teak (originally from Asia) -E Africa; Eucalyptus (originally from Australia)

Question 32

Forest exploitation & management- methods; what are the advantages of single-species plantations?

Answer 32

-Growing monoculture of one tree species can make management of plantation easier -Activities like planting, thinning & felling can be carried out over large areas at same time

Question 33

Forest exploitation & management- methods; why is close planting of trees used in forests and why can this be disadvantageous?

Answer 33

-Planting all seedlings close together makes trees compete w/ each other for light so grow tall & straight -Low light levels at ground level inhibit growth of other plants that may compete w/ trees for water/nutrients -Loss of these plants & species depending upon them reduces wildlife diversity of forest

Question 34

Forest exploitation & management- methods; why is a simple age structure in forests used and why is this also disadvantageous?

Answer 34

-Planting large areas of trees at same time makes tree management easy -Trees will all be similar sizes & need similar management activities at same time -But, having trees of similar sizes reduces variety of abiotic factors compared w/ having plantation w/ trees of diff ages & sizes + reduces diversity of wildlife species that can survive -Trees in commercial plantations are usually felled when income will be greatest; normally when they're approaching full size a growth rate starting to ↓. This is v diff from natural forest; contain old trees w/ dead wood that supports many invertebrates & species feeding on them, like woodpeckers

Question 35

Deforestation; how much of the world's original forest area has been lost to human activities?

Answer 35

1/3

Question 36

Deforestation; what are the two main causes?

Answer 36

-Deliberate removing of forests to make space for another land use, eg agriculture & urban development -Unsustainable exploitation; above Maximum Sustainable Yield

Question 37

Deforestation; how does agricultural expansion cause the loss of forests?

Answer 37

-Growth of local population increases demand for food, so more land must be cleared for farming -Forest clearance for commercial cash crop agriculture where produce may be taken to cities/exported

Question 38

Deforestation; what are examples of deforestation for agricultural expansion?

Answer 38

-Rainforest clearance in s America to grow sugar cane & soya beans/ranch cattle -Rainforest clearance in SE Asia to grow palm oil

Question 39

Deforestation; how can forest loss due to mineral extraction be impactful?

Answer 39

Forest clearance for mining & associated infrastructure affects relatively small total area but can have important local impacts

Question 40

Deforestation; how can reservoirs cause forest loss + example?

Answer 40

-Reservoirs for public supply, irrigation, hydroelectric power (HEP) can replace forests -Expansion of HEP in S America has caused loss of large areas of tropical rainforest

Question 41

Deforestation; how can urbanisation cause forest loss?

Answer 41

-Expansion of urban areas con cause direct loss of forest -Also increases demand for fuel & food which can cause further forest loss

Question 42

Deforestation; what are the impacts of deforestation for transport infrastructure?

Answer 42

Area of forest lost by construction of roads, railways, airports isn't large but can have other impacts; -Roads + railways can create barriers to movement of wildlife & cause population fragmentation -Improved transport systems increase accessibility & make it easier to take out resources like felled trees/agricultural produce that may increase rate of forest clearance

Question 43

Deforestation- unsustainable exploitation; why may timber resources be exploited sustainably/unsustainably?

Answer 43

-Softwood made by conifers like pine & spruce is often made sustainably w/ replanting to replace harvested areas, eg in Scandinavia & Canada -Hardwood species like teak & mahogany grow more slowly than conifers so it's harder to commercially manage hardwood plantation as may take longer to make a saleable crop -So, a lot of harvested hardwood come from mixed forests that are clear felled & may not be replanted

Question 44

Deforestation- unsustainable exploitation; why is wood highly demanded as a fuel?

Answer 44

-Many people rely on wood as their domestic energy source than any other fuel -It’s not necessarily fuel choice but many in LEDCs can't afford alternative energy sources & have to use wood, even though its exploitation may be unsustainable

Question 45

Deforestation- unsustainable exploitation; why is charcoal used as a fuel and why is this unsustainable?

Answer 45

-In towns & cities, there may be greater demand for charcoal which produces less smoke when burnt -Production of charcoal involves partial combustion of wood w/ shortage of air -Much of the energy value of wood is lost in this process which increases rate of forest clearance to satisfy demand for energy

Question 46

Deforestation- unsustainable exploitation; why are forests cleared for livestock fodder and why is this unsustainable?

Answer 46

-It's unusual for forest areas to be cleared to provide livestock food -But, in LEDCs, in areas of mixed woodland & grassland, farmers may cut branches off trees if there's a shortage of ground-level grazing -If this exceeds growth of trees, then forest may gradually be degraded & disappear

Question 47

Deforestation- effects; how does deforestation cause the loss of forest resources?

Answer 47

-Forest products are renewable but can be depleted; deforestation stops their production completely -Timber, fuels, fibres, medicines

Question 48

Deforestation- effects; what ecological impacts does deforestation cause?

Answer 48

-Reduced biodiversity -Loss of species -Fragmentation of remaining forest areas

Question 49

Deforestation- effects; how does deforestation cause changes to hydrology?

Answer 49

-Reduced interception & transpiration -Increased runoff

Question 50

Deforestation- effects; in what ways does deforestation impact soils?

Answer 50

-Reduced soil formation -Less dead organic matter -Increased soil erosion -Less protection of soil by vegetation & leaf litter -Reduced soil organic matter -Reduced root binding

Question 51

Deforestation- effects; what are the climate impacts that deforestation causes?

Answer 51

-Increased albedo -Reduced carbon sequestration & carbon reservoir -Reduced rainfall downwind

Question 52

Sustainable forest management; how can forests be exploited sustainably and what could this involve?

Answer 52

-If harvesting rates & environmental impacts are carefully managed -May involve combo of environmentally beneficial methods used in traditional forest management w/ commercially productive methods of modern plantation forestry

Question 53

Sustainable forest management; which countries have had large-scale tree planting projects?

Answer 53

China, Cuba & Bhutan

Question 54

Features of sustainability managed forests; what should harvesting rates be like?

Answer 54

Rate of resource removal must be no greater than the Maximum Sustainable Yield

Question 55

Features of sustainability managed forests; why are mixed species plantations important?

Answer 55

Wildlife biodiversity is increased by growing multiple species as there's an increase in food choices, inter-species relationships & niches

Question 56

Features of sustainability managed forests; why are indigenous species important?

Answer 56

If they're cultivated, it's more likely other indigenous species will benefit eg birds & insects

Question 57

Features of sustainability managed forests; why is a mixed age structure of trees important?

Answer 57

-Having a plantation w/ trees of diff ages produces greater diversity of abiotic factors like light levels, temp, wind velocity -This increases biodiversity of other species living in the forest

Question 58

Features of sustainability managed forests; when is clear-felling vs selective logging done and why?

Answer 58

-Clear-felling a large area at one time is easy. It can be commercially advantageous if trees have been grown as single species monoculture as all trees may be ready for harvesting at same time -In mixed-species plantations/natural forests, diff trees will be ready for felling at diff times; selective logging

Question 59

Features of sustainability managed forests; what are the advantages and disadvantages of selective logging?

Answer 59

-More costly as it's more labour-intensive -But, it gains max benefit from forest timber resource over longer time periods -It's also good for wildlife as removal of individual trees leaves smaller clearings w/ smaller impact on survival of remaining wildlife populations -Wildlife that's lost its tree habitat won't have to move too far to find a new habitat