8. Temperate forests

Question 1

What is temperate zone? 7

Answer 1

1. 4 seasons - winter, spring, summer, autumn
2. moderate temperatures - 5-20 degrees c
3. no extreme weather events
4. above tropics and below poles - between 40 and 60-70 degrees north and south of the equator
5. altitude is not too high
6. long, active growing season - may be some hibernation but animals active for 8-10 months
7. does not include unique climate of mediterranean

Question 2

What is the relationship between the temperate zone and climate? 3

Answer 2

1. temperate zone has average yearly temp. of 5-20 degrees c
2. has approximate global bands but not clear cut like latitude
3. eg. compared to other points on our latitude, UK is warm and wet due to gulf stream

Question 3

What is the relationship between the temperate zone and rainfall? 3

Answer 3

1. rainfall helps to determine climate
2. temperate zone has mean annual rainfall of 25-200cm
3. rainfall does not match latitude or temperature bands

Question 4

What are temperate climates? 3

Answer 4

1. vary from oceanic ( moderated and wet, coastal areas) to continental (highly seasonal and seasonally dry, away from coast)
2. Climates are defined by temperature and rainfall combo
3. most of temperature zone is in northern hemisphere, which is why we have lower co2 in summer - more photosynthesis

Question 5

What grows in temperate zones? 5

Answer 5

1. deciduous forest
2. temperate grassland eg. USA and russia
3. temperate rainforest
4. some heathland - artificial
5. these are biomes

Question 6

Who were the three leaders in developing the biome concept, and when? 9

Answer 6

1. in 1893, american zoologist CH Merriam developed the life zones concept
2. he mapped north american fauna, paying attention to altitude and temperature
3. noticed patterns
4. in 1947, LR Holdridge mapped botany
5. he took a more globally relevant view, and introduced idea of water availability
6. He came up with a model that determined humidity by amount of water arriving (rain) and leaving (evaporation etc)
7. This defined a number of habitats, but was very complex
8. 1975 - RH Whittaker developed biomes by plotting temp vs precipitation and compartmentalising the curve - simpler version of Holdridge’s
9. Climax vegetation depends on regional climate

Question 7

How are temperate zones globally distributed? 4

Answer 7

1. Deciduous temperate forest found in north east america, east asian coast and western europe
2. temperate rainforest has a smaller biome and requires more than 1.4m annual rainfall
3. Including North west america, south america and eastern asia, australia and new zeland
4. temperate grassland found in central north america, central eurasia and east australia

Question 8

Is europe really a temperate forest biome? 9

Answer 8

1. Partial grassland according to Whittaker diagram
2. climax community of uk is forest
3. climate reconstruction has been attempted to find historical vegetation
4. pollination fossils from lake sediment and peat suggest trees present, as trees produce good, wind dispersed pollen for fossilisation with only a few members
5. grass does this too but has to flower, but only has flowers when left alone - grazed grass may not produce pollen
6. Frans Vera, 2000, suggested Europe is naturally opensavannah with woodland glades
7. Closed forest is inconsistent with large mammals that would have grazed eg. irish elk
8. in response, woodland-shrubland entered into whittaker biome diagram
9. grazing determines grass vs trees, which may cause shift

Question 9

What is the impact of water and grazers on the temperate biome? 6

Answer 9

1. Trees need water to outgrow competitors
2. trees have advantage in wet zones, but limited in drier zones
3. trees that can’t grow faster than they’re eaten will not dominate
4. basal meristem allows grass to survive when grazed
5. fire and biotic factors (human) also impact
6. forest usually found in oceanic areas

Question 10

What are temperate rainforests? 4

Answer 10

1. Have more than 1400mm rain annually
2. found in north west america, chile, south africa, australia and new zeland
3. parts of wales and ireland
4. many dominated by evergreen trees eg. redwood, but european usually deciduous

Question 11

Describe the differences between temperate evergreens and deciduous. 8

Answer 11

1. Temperate trees face stresses from cold winters eg. tissue freezing and water loss
2. Evergreens protect themselves with small, tough leaves with dense tissues, which can resist frost and water loss so reduce nutrient loss
3. Inefficient - low level photosynthesis, but have a quick start in spring and keep understory in the shade
4. Deciduous trees shed their leaves, rather than trying to keep them alive - diseased and damaged tissues are lost
5. more efficient, but energy and nutrients that go into them are wasted
6. not regained until leaf litter broken down
7. evergreens are more common in oceanic areas, with only moderate temp. fluctuations
8. britain should have more evergreens, but in europe, few were available to colonise post ice-age

Question 12

Mind the gap: how open were european primeval forests? H. Birks. 2005. Trends in ecology and evolution.

What are the competing hypotheses? 3

Answer 12

1. Vera argued abundance of oak and hazel pollen means open canopy as this is required for oak and hazel to regenerate
2. openness caused by herbivore grazing
3. the opposing high forest hypothesis (watt) claims that lack of open space regulates herbivores

Question 13

Mind the gap: how open were european primeval forests? H. Birks. 2005. Trends in ecology and evolution.

How are the competing hypotheses tested? 5

Answer 13

1. ireland supported few large herbivores at this time
2. pollen samples from ireland and lowland europe statistically similar
3. large herbivores had no large impact
4. but sample area large - many ecosystems possible in space
5. pollen data collected from small hollows suggests lack of open canopies - too much of it (60%+) from trees