20 a Day (3) Flashcards
The main reason why rides and forest edges host a variety of rare species is because…
They have many different microclimates available due to differing levels of sunlight and shelter.
Why are forest edges so species rich? (3 Points)
Both habitats, specialised, migration
- They contain species from both the forest itself and the adjacent habitat.
- They’re home to specialised species that like the various different microclimates that edges offer.
- Many species also use forest edges for migration and dispersal.
Does the UK have a lot of edge habitats? Why?
Yes, because it has a long history of deforestation and woodland management. In fact, the UK has some of the most fragmented woodlands in the world.
Woodlands consist of edge habitats and interior habitats. How large does a forest have to be to prevent edge habitats from dominating?
At least 5 hectares.
What does the UK have more of: woodland edge habitats or woodland interior habitats?
It has considerably more woodland edge habitats because of how fragmented our woodlands are.
What silvicultural management system creates woodland edge habitats?
Coppicing!
Traditional management (e.g., coppicing) resulted in unnaturally high populations of what broad group of species?
Species adapted to woodland edge habitats.
What’s the main reason as to why coniferous plantations are so species poor?
Because the ground within plantations receives such little solar radiation.
What are the most species-rich parts of a coniferous plantation?
Edges and rides (because they’re exposed to sunlight, unlike the plantation’s interior).
If coniferous trees are felled within a plantation, will ground flora return?
Hopefully. The reason is why is that edges and rides should serve as reservoirs of seeds (these areas are the only areas to receive lots of sunlight).
What sorts of woodland edges contain the most species? (2 Points)
- Edges that are between woodlands and open habitats
- Edges that are permanent (e.g., not just edges between different successional stages)
What is the most influential environmental gradient? (2 Extra points)
Solar radiation
* It has important implications for the development of understorey vegetation
* And for the value of edges and gaps to light or heat demanding species.
Do forest edges have mild or extreme temperatures and humidities?
They have extreme temperatures and humidities (higher temperatures and lower humidities compared to the forest interior).
Why do forest edges tend to have more extreme temperatures and humidities?
Because wind speeds are lower at the forest edge.
The formation of what two watery things is greater at a forest’s edge?
- Dew
- Frost
Where is litter decomposition the greatest within a forest: the interior or the edge?
The edge.
Why are east-west ride important?
Because these rides receive more solar radiation (in terms of the actual duration of exposure to radiation) over a 24 hour period.
What’s an important thing to remember in regards to an east-west ride’s width?
It needs to be larger than the heights of the surrounding trees in order fot the ride to obtain the benefit of prolonged solar radiaiton exposure.
When widening an east-west ride, what trees should you remove? Why?
- Those immediately to the north of you.
- Northern tree removal increases the direct sunlight received by the ride and the south-facing edge (trees to the north of you).
Why might you remove trees on the northern side of an east-west ride (even though the northern edge receives lots of solar radiation)?
Because this will greatly increases light penetration into the stand and onto the woodland floor.
Along which rides is tree height usually unimportant? Why?
North-south rides. This is because these rides receive most of their solar radiation during midday.
What sort of slopes are usually hotspots for biodiversity? Why?
South-facing slopes. This is because they receive greater overall and peak solar radiation than level ground (so they receive more radiation, and the maximum amount they can receive at any given time will be greater).
Along a north-south ride, what side receives more solar radiation: the west side or the east side?
The west side (it receives ~2 hours of solar radiation a day, compared to just ~1 hour for east sides). I’m not sure why.
Where would you expect to create a particularly wide ride?
On a north-facing slope (these receive less solar radiation than south-facing slopes).
Even though east-west rides receive more hours of solar radiation, why do they have less heating power?
Because of lower sun angles (north-south rides receive sunlight during midday).
How can you enhance the value of south-facing slopes for wildlife?
Through scarification - this will create basking sites made of bare soils.
Even though tree cover reduces ground temperatures, at least they’re more…
Stable!
On north facing slopes, east-west rides only receive solar radiation during the ______________ and the _______________.
Early morning and the late afternoon.
How long does it take for a forest edge to become mature?
70 years
What shouldn’t the groundflora of a site be representative of?
The seedbank - the seeds contained within may be very different from what’s already present.
Give one woodland species that cannot tolerate canopy removal.
Dog’s mercury. It cannot tolerate intense sunlight. When it is exposed to the sun, leaf necrosis occurs.
Can bluebells tolerate canopy removal?
Yesn’t - they can tolerate exposure to the sky for a while, but not forever.
Give two flowers that show rapid growth rates following the removal of a canopy.
- Ground ivy
- Violets
What do muntjac deer and roe deer have in common?
They tend to focus their feeding activity on trees and herbs, while they avoid grasses altogether.
How many red deer are required in order for them to have a noticable effect on vegetation?
4 deer per km2.
At what point will red deer completely halt all natural regeneration?
When they occur at densities of 25 individuals per km2 or greater.
Why is aspen a particularly absent tree species in the UK?
Because it’s highly palatable to deer.
When deer occur at low densities, what plant species would you expect to suffer?
Only the most palatable species - as deer densities increase, less palatable species are targeted.
What’s notable about horse grazing?
Horses will consume species that cattle and sheep often ignore, such as thistles.
What problematic species is consumed by deer? Is there any benefit to this?
- Brambles - deer love to eat the leaves.
- The loss of brambles may create space for less competitive plant species to grow
Why might sycamores become abundant when deer are present (even at low densities)?
- Deer selectively consume oaks because they think they’re yummy
- Therefore, less palatable sycamores will take over
Why would fencing-in an area cause the amount of brambles inside the area to increase?
Because deer can’t consume the bramble leaves, which they find very yummy
Within a forest, where is herbivory the greatest?
Within open areas (glades and rides).
What is the most conspicuous (noticable) effect of grazing/browsing? What does this result in a reduction in?
- The reduction in vegetation height or above ground biomass.
- This results in a reduction of dead biomass.
Why might some rare plants disappear from a forest if grazers are excluded?
Grazing animals usually also remove taller or faster growing dominants, giving smaller, slower growing plants an opportunity to reproduce.
Within a woodland, the density of herbivores required to maximise ______________________ is much greater than that for _______________________________.
Within a woodland, the density of herbivores required to maximise diversity of ground-layer plants is much greater than that for acceptable tree survival. This means that some trees may need to be lost for ground flora to develop.
Give two diversities that increase within a woodland when light to moderate grazing is allowed.
- Ground flora species diversity
- Structural diversity of ground vegetation
When it comes to habitat quality, what’s an important quality of a woodland for vertebrates? (Hint: not plant species diversity).
Woodland structural diversity.
How can a flower increase its chances of becoming a nice food plant for some very nice larvae?
If it’s large and conspicuous among the general vegetation; not hidden and not hard to find.
What sort of trees can increase the foraging activity of bats?
Trees that are foodplants of nocturnally active moths.
Give three groups of trees that can increase the foraging activity of bats.
- Birch trees
- Willow trees
- Cherry trees
These are all food plants for nocturnal moths!
What group insects respond positively to ride creation? Are there any catches?
- Butterflies
- But significant changes will only be seen after 3 years
- Rides may have to be as large as 20m wide
Give one species of butterfly that’s entirely dependent on rides (and roads) (2 Points)
The purple emperor
* It breeds on willows that grow in sheltered rides and roadsides
* It depends upon open rides for its courtship and territorial flight
Give one butterfly species that has responded positively to the general reduction in coppicing. Why?
- The white admiral
- It uses honeysuckle that grows in shaded areas as a larval foodplant
The vast majority of insects prefer sunny rides. Give two insect species that don’t (how much shade do they like exactly?)
- The speckled wood and green-veined white
- They like 40-90% shade (most species of invertebrate prefer less than 10% shade)
Why might tipped-up root plates of wind-blown trees be useful?
Because they can be colonised by bees that usually burrow in the ground.
What’s the minimum width of a scrubby margin along a ride?
5m (it needs to be this big in order to benefit biodiversity).
What two other mousey species can field voles outcompete? What can cause them to do this?
- Bank voles
- Wood mice
- Field voles will become dominant if grasslands become too vast - maintaining scrub cover will allow all three species to live in harmony
When creating arboreal bridges for dormice, do they need to be really elaborate?
No - a single branch that bridges the space between two canopies will do.
Why is a diversity of tree species important for dormice?
To provide a continuous sequence of flowers and fruits for dormice between Spring and Autumn.
What two things are required before starting any management that’s intended to bring conservation benefits?
Clear goals and objectives must be decided.
Give a diagram that shows how ride crossroads should be managed.
The simple reason why we must use native trees is because…
…They have co-evolved with our own native wildlife.
By what percentage have our woodlands increased over the past 20 years?
1% (the UK’s woodland coverage was 12% 20 years ago, now it’s roiughly 13%).
What percentage of our woodlands are broadleaved? What about coniferous?
- 49% broadleaved
- 51% confierous
Why do trees enhance crop yields?
- Trees reduce soil erosion
- They also modify crop microclimates by reducing wind speeds and evapotranspiration losses (improving crop water efficiency)
Most species-rich grasslands are located on marginal agricultural lands. What’s the downside of this?
Marginal agricultural lands are often seen as areas that can be planted with trees (remember that all rewilding efforts are practically carried out on marginal lands).
Woodland creation should never require the artificial modification of…
…Artificially modifying soil conditions to enable trees, or those of a specific species, to grow.
What are shadow woods? How can they be restored?
Remnants of ancient woodlands. They can be restored to their former glory through the use of maps or any other historical evidence.
Where are deer populations especially likely to be a problem?
Where large deer populations are supported by cropping systems; for example, over-wintering cereals which provide year-round food.
Give a statistic that shows just how bad herbivore damage is (Hint: a percentage relating to native woodlands).
At least 40% of existing native woodlands in Britain are in unfavourable ecological condition due to excessive herbivore damage.
Why should the colonisation of areas by native trees and shrubs be encourgaed (2 Points - both related to adaptation and genetics).
- To promote natural selection and climate change adaptation
- And to conserve distinctive genetic patterns
In many cases, carbon capture and storage is highly compatible with nature conservation aims. However, it can involve compromises. Give an example.
Where regular intervention has been identified as important for the nature conservation value of the site (e.g. retaining early stage woodland for bird species or woodland plants).
Why is natural colonisation of trees and shrubs a critical process during woodland creation? What can be used as an alternative to natural colonisation (3 Points)?
- Because it allows natural selection to build adaptation to site conditions.
- By creating complex habitat mosaics with trees that are well adapted to site conditions, you can build landscapes that are resilient to current and future stresses.
- Using locally sourced trees and seeds can be used as a substitute for natural colonisation.
What are the two main ways in which seeds are artifically distributed?
- Sowing into the soil
- Broadcasting onto the soil’s surface
What’s a downside of broadcasting seeds instead of sowing them into the ground?
Seeds are more likely to be eaten
If you’re going to sow tree seeds, when might significant ground preparation be required?
If the site is dominated by grasses or bracken to reduce competition during germination and emergence.
If you’re going to plant tree seeds, when might seed predation be a big issue (Hint: not when broadcasting seeds)?
- If the site is located close to dense areas of grass
- These dense grass areas are likely to be home to many small, seed-eating mammals
Should tree guards be placed firmly into the soil, or left a bit loose?
They should be planted firmly into the soil.
Once you’ve placed a tree guard around a sapling, can you just leave it be?
Tree guards should be regularly checked during the early years of establishment to ensure that they are correctly staked (upright) and functioning effectively (firmly in contact with the soil and weed-free).
Give two species that indicate nutrient enrichment
- Nettles
- Goose grass (see below)
What’s the main sign of deer damage? Why?
- The ends of shoots will be frayed/ragged.
- Deer are ungulates, like sheep and goats, so they have a palate where their top teeth would be. It basically like a really hard gum.
What’s the only chainsaw component that requires greasing?
The needle bearing (part of the clutch)
What shape should a cutter’s depth gauge/raker be?
Curved (and not square)
How do you check the wear on a chainsaw’s sprocket?
By using this thing
