Think about autumn. In the UK, it autumn is associated with cold winds, morning mist, Pumpkin spiced lattes and of course, falling leaves. Throughout this season of earthy orange hues, deciduous trees shed their leaves and slow their metabolisms, preparing to survive the winter. But this pretty phenomenon doesn't happen everywhere. Travel northwest to Sweden, and you'll see trees that keep their leaves all year round. Why are deciduous trees found in some places, and not others? Keep reading to find out!
Deciduous Woodland Ecosystems
Let's begin with a definition.
Deciduous woodland ecosystems are temperate forests dominated by deciduous trees.
Broadleaved woodland contains broad leaved trees that vary in shape and which don't have needles.
Deciduous woodland ecosystems are found within the forest biome.
A biome is a large area characterised by its vegetation, soil, climate, and wildlife. There are five major biomes:
- Aquatic
- Grassland
- Desert
- Tundra (extremely inhospitable conditions, barren and treeless)
- Forest
Deciduous Woodland: Vegetation and Fauna
The distinctive feature of deciduous woodland is deciduous trees.
Deciduous plants shed their leaves annually.
Deciduous plants shed their leaves in autumn, before the cold winter months. Low temperatures would reduce photosynthesis, and make water uptake from frozen soil difficult. Deciduous trees don't just lose their leaves – they can slow down their metabolism to conserve energy throughout winter.
Fig. 4 - Life Studies reveals how Lowell's relationship with his family influenced his poetry and prose.
Plants end their dormancy period at the beginning of spring, when temperatures begin to rise and organisms begin to bud.
Deciduous tree species include oak, beech, elm, and maple.
Layered Vegetation
Deciduous woodlands have three distinctive vertical layers.
The Canopy
The canopy is the upper layer of the woodland, formed by mature tree crowns. Light availability is high, enabling rapid photosynthesis. As a result, the canopy supports the majority of the woodland's primary productivity. The canopy also provides protection from strong winds, harsh sunlight, and heavy precipitation.
The tree crown is, as the name suggests, the top part of the tree. A dominant tree crown reaches over all other plants in the forest.
The Understorey
The middle layer of the woodland is known as the understorey, usually comprised of shrubs, herbs, and seedlings of canopy trees. The understorey receives much less sunlight, so plants need to be shade-tolerant. Humidity levels are higher than in the canopy.
The Forest Floor
The lowest layer of the woodland is the forest floor. It's made of soil, decaying plants, and epiphytes.
Epiphytes are small organisms that grow on the surface of plants, deriving their moisture and nutrients from their physical environment or nearby debris.
Examples of epiphytes in deciduous forests include mosses, lichens, and ferns.
Sunlight levels are low, and humidity is high. The forest floor plays an important role in nutrient transfer between the vegetation and the soil.
Fauna of Deciduous Woodland
Deciduous woodlands are home to a wide variety of fauna, including mammals, birds, snakes, and invertebrates. Animals can be found within all three vertical layers.
Animal populations in deciduous woodlands change throughout the year. Many mammals hibernate during colder winter months, while bird species migrate to warmer climates.
Swallows migrate 6000 miles from the UK to South Africa during the winter months, travelling approximately 200 miles per day.
Deciduous Woodland: Locations
Deciduous woodlands are found around the world, but are mostly concentrated in mid-latitude areas of the Northern Hemisphere, such as:
Locations in the Southern Hemisphere include:
Chile
South Africa
Australia
New Zealand
These ecosystems thrive in mountainous areas, and regions with a range of soil types.
Deciduous Woodland: Climate
To support deciduous woodlands, a region needs seasonal temperature variation and year-round rainfall.
Temperature
Deciduous forests experience seasonal temperature changes. Winters average 0ºC, while summers can reach up to 35ºC. The difference between summer and winter temperatures is significant, but not as extreme as some ecosystems.
Steppes (dry grassland ecosystems) range from -40ºC in winter to 40ºC in summer. They make deciduous woodlands look mild!
Precipitation
Deciduous woodlands don't have dry and wet seasons. Instead, significant amounts of rain fall throughout the year, including summer rain and some winter snow. Precipitation levels range from 70-200 cm annually.
As a result, deciduous woodlands have a regular water supply.
Fig. 2 - a deciduous woodland ecosystem in the UK, experiencing cold winter temperatures and snowfall. Unsplash
Deciduous Woodland: Characteristics and Importance
Woodland ecosystems are characterised by a high biodiversity. They are home to a wide range of animals, plants, and fungi.
Why is biodiversity so high in deciduous forests?
- Distinct layers providing a range of physical structures and habitats
- Year-round water availability, supporting survival and functioning of organisms
- Nutrient recycling promoting plant growth
Deciduous woodlands are considered biodiversity hotspots, giving them a range of important functions.
Resources
Deciduous woodlands provide resources to humans in the form of ecosystem services.
For more information, check out our article Ecosystem Services!
| Ecosystem Services | What Are They? | Ecosystem Services in Deciduous Woodlands |
| Provisioning Services | Physical products that humans obtain from ecosystems. | |
| Cultural Services | Non-material benefits of nature that are enjoyed by humans. | - Recreation
- Aesthetic value
- Education
|
| Regulating Services | Services that nature provides that regulate the environment. | |
| Supporting Services | Underpinning services that enable the above services to function effectively. | - Photosynthesis
- Hydrological cycle
- Nutrient cycling
- Soil formation
|
Let's focus on two particular regulating services of deciduous woodlands – climate regulation and control of soil erosion.
Climate Regulation
Woodlands play a critical role in carbon storage. When trees photosynthesise, they extract carbon dioxide from the atmosphere. Carbon dioxide acts as a greenhouse gas, trapping heat in the Earth's atmosphere and leading to increased temperatures.
Furthermore, forests affect atmospheric moisture and rainfall patterns by evapotranspiration.
Evapotranspiration is evaporation from soil and plant surfaces, and transpiration of water by plants.
It's estimated that 40% of rain over land originates from evapotranspiration processes.
Control of Soil Erosion
Trees prevent soil erosion in multiple ways:
Intercepting heavy rainfall to stop 'splash erosion'
Acting as a windbreak
Roots binding soil to sloping ground
Reducing the amount of water in the soil through transpiration
Soil erosion control is crucial for preventing water pollution, protecting natural habitats, and providing storm drainage for urban infrastructure.
Threats to Deciduous Woodland
These diverse and important ecosystems are under threat.
Deforestation
A rapidly increasing human population has led to widespread deforestation to provide land area, resources, and opportunities for agriculture.
Deforestation is the purposeful removal of trees.
Deforestation leads to habitat damage and biodiversity loss. It also impacts climate regulation and soil erosion.
Fragmentation of Remaining Woodland
Destructive activities, such as deforestation, can result in habitat fragmentation.
The main problem associated with habitat fragmentation is species loss. Smaller habitats result in smaller populations, which face a higher risk of extinction. Furthermore, disconnected habitats negatively impact dispersion and migration. Fragmented habitats also have a higher edge area, making them subject to edge effects.
Edge effects are the changes in population or community structure that occur at the boundary of a habitat.
Biodiversity is lower at the edge of a habitat than at its centre.
Poor Management
Poorly managed woodlands face a higher risk of wildfires.
A wildfire is an unplanned, uncontrolled and unpredictable fire in a woodland habitat.
Wildfires are common after hot summers; the heat has dried out vegetation, making it easy to ignite.
A lack of woodland management leads to thick, overgrown forests, where fire can spread quickly. Furthermore, unmanaged forest often lacks regulation on campfires and barbecues – common causes of accidental wildfires.
Conservation of Deciduous Woodland
How are deciduous woodlands conserved to prevent further degradation of these threatened ecosystems?
Protected Areas
Protected areas are locations that receive protection because of recognised ecological or cultural value.
Approximately 7% of Earth's land surface is part of a designated protected area.
Protected areas limit deforestation, habitat damage, and unsustainable exploitation of natural resources.
Legal Protection of UK Ancient Woodland
The UK's ancient woodlands are protected by law. Any developments near a site of ancient woodland require planning permission, where the developer must:
avoid damage
mitigate against any damage
compensate for loss or damage
These legal requirements help protect over 600,000 hectares of ancient woodland in the UK.
Ancient woodlands are areas of woodland that have persisted since before 1600 AD. They support complex, irreplaceable habitats.
Many ancient woodlands have been mapped, but others can be spotted by indicator species. The presence of these plants, animals, or fungi suggest that a site has been continuously wooded for a long period of time.
Ancient woodland indicator species include bluebells, lemon slugs, and barnacle lichens.
Fig. 3 - Bluebells are an important indicator species for ancient woodland ecosystems. Unsplash.
Conservation Management
Deciduous woodland ecosystems can be conserved using coppicing and pollarding management strategies.
Coppicing
It may sound counterintuitive, but coppicing actually promotes woodland biodiversity. Regular coppicing lets light reach the ground, enabling other species to grow. Furthermore, coppicing promotes a varied age structure. This provides diverse habitat and cover.
Coppicing is a technique where trees are repeatedly felled at the base, then allowed to regrow.
Pollarding
Regular pollarding leads to the rapid formation of tree hollows, a habitat associated with ancient woodlands. It restores saproxylic (related to dead and decaying wood) habitats, and conserves hollow-dependent fauna.
Pollarding is a pruning system where the upper branches of a tree are removed to promote new growth.
I hope that this article has explained Deciduous Woodlands for you. Remember that they are temperature forests dominated by deciduous trees (that lose their leaves every year). Deciduous woodlands experience seasonal temperature variation and large amounts of precipitation throughout the year.
Deciduous Woodlands - Key takeaways
- Deciduous woodland ecosystems are temperate forests dominated by deciduous trees. They are found within the forest biome.
- The distinctive feature of deciduous woodlands is deciduous trees, which shed their leaves annually. Deciduous woodlands are split into three vertical layers: the canopy, the understorey, and the forest floor.
- Deciduous woodland habitats are mostly concentrated in mid-latitude areas of the Northern Hemisphere, but some are found in the Southern Hemisphere too. To support a deciduous woodland ecosystems, a region requires temperature seasonality and precipitation throughout the year.
- Deciduous woodland ecosystems are characterised by a high biodiversity. This provides a range of ecosystems services, and plays an important role in climate regulation and preventing soil erosion. Threats to deciduous woodlands include deforestation, fragmentation, and poor management.
- Conservation techniques include establishing protected areas, legislating against damage, and management strategies such as coppicing and pollarding.
1. British Trust for Ornithology, Swallow guide: migration, nesting and where to see, 2020
2. Climate Change Post, More than carbon storage - The role of forests in climate change, 2017
3. Michael E. Ritter, Midlatitude Steppe, The Physical Environment: an Introduction to Physical Geography, 2022
4. Neil Campbell, Biology: A Global Approach, Eleventh Edition, 2018
5. The Woodland Trust, Ancient Woodland, 2022
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