Climatic Climax in the UK (AQA A Level Geography)

• The UK has several types of natural climax woodland:
  • Ancient woodlands - areas that have had tree cover for hundreds of years and undisturbed by human development
  • Broadleaf woodlands - trees that do not have needles and are the most common in the UK
  • Caledonian forest and native conifer woods - found in mainly in Scotland (most coniferous forests are not native) and species include Scots pine, juniper, birch, willow, rowan and aspen
  • Temperate rainforest - very rare in the UK but are found in some coastal areas with high rainfall and humidity and low temperature variations (ravines and gorges)
  • Wet woodland - found on wet soils such as floodplains, edges of lakes and rivers
• There are 3 other types of woodland found in the UK, but these are planned and managed woodlands
  • Plantation woods - young, fast growing trees, and used for commercial purposes
  • Wood pasture and parkland - mixture of habitats - scrub, shrub, dense woodlands and open grass or heather
  • Urban woodland - planted to create greenspaces and combines different trees across the urban area

Broadleaf woodlands

• These woodlands are the most common and best adapted to the UK's temperate climate and are classified as temperate deciduous woodlands, with oak, beech and elm being the dominant climax species of trees 
• The cycle of shedding and gaining leaves allows the woodland floor and understorey to contain a wide variety of flora and fauna

Climatic differences

• Location, soil, altitude and the availability of water all influence the species that can thrive there
• Woods with oak and birch can flourish in both highland and lowland environments
• These occur on more acidic and infertile soils, often with shrubs such as heather, bilberry and bracken
• Along parts of the western coast of the UK, are the internationally rare temperate oceanic rainforest of oak, oceanic ash and Atlantic hazel
• Native beech woods thrive in chalky soils in southern England and Wales, like those of the Chilterns and the Cotswolds
• Ash woodland grows in areas of limestone and other base-rich soils, with plenty of shrub understory growth
• Willows and dwarf birch grow in mountainous regions

Layers of a typical deciduous woodland

• Unlike the tropical rainforest, deciduous woodlands have 3 distinctive vertical layers
  • Canopy
  • Understory
  • Woodland floor
• Canopy layer
  • This is the uppermost layer of the woodland, formed by mature tree crowns
  • Rate of photosynthesis is high due to the availability of light is high
  • The majority of the woodland's primary productivity occurs in the canopy 
  • The canopy protects the lower layers from strong winds, harsh sunlight, and heavy precipitation
  • Usually consist of large broad leaved trees, such as oak, beech and elm
• Understory
  • Humidity levels are higher than in the canopy
  • Some light filters through the canopy, allowing layering of vegetation below
  • The sub-canopy grows in spaces between the taller trees, where there is more water when it rains and more light
    • The shrub layer contains species like hazel, ash and holly, which are shade-tolerant
• Woodland floor
  • Grass, bracken or bluebells can be found in the ground layer
  • The woodland floor has low sunlight levels with high humidity, aiding the rate of decomposition and nutrient transfer between the stores
  • Detritus from plant and animal fallout is quickly decomposed by detritivores (earthworms, beetles and flies) and fungi, adding to humus and soil levels

Simplified diagram showing the layers of a deciduous woodland in the UK