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Birch
Tree. Height to
25m. Leaves 5-
7cm x 2-2.5cm
Oak
Large deciduous
tree. Height to
30m. Leaves 5-
12cm
Juniper
Shrub. Height: small tree to 10m. Leaves: whorls of 3, 5-19mm with spiny point
Scots Pine
Tree. Height to
30m. Leaves-2
on each short
shoot, 3 - 8cm x
1-2 mm
Rowan
Slender tree.
Height to 15m.
Leaves 10-25cm
Woodland species:
Scots Pine/ Pinus sylvestris
Juniper/ Juniperus communis
Birch/ Betula pendula
Rowan/ Sorbus aucuparia
Aspen/ Populus tremula
Oak/ Quercus robur
Hazel/ Corylus avellana
Holly/ Ilex spp.
Hawthorn/ Crataegus spp.
Bird-Cherry/ Prunus padus
Willows/ Salix spp.
Ash/ Fraxinus spp.
Impact Assess : Woodland
Aim
The aim of this guide is to describe methods of assessing woodland habitat relevant to deer managers*.
Move
Woodland 1: natural Caledonian forest...
Woodland 2: signs of high impact: growth of rowan restricted due to browsing pressure
Woodland 3: signs of low impact: birch seedling growth above that of vegetation
Woodland 4: measuring from the apical (terminal) bud to give the length of leader (one year's growth)
Woodland 5: example of plot layout for Nearest Neighbour Method1
For information on how many seedlings, trees and plots to sample and what time of year to measure, see BPG Habitat Impact Assessment: Principles in Practice
Introduction
Native semi natural woodland includes a range of woodlands dominated by native species such as Scots pine, silver and downy birch, sessile oak and ash (see species list overleaf). Other tree species found in these woods may include aspen, rowan and juniper. Scottish woodlands are ‘semi’ natural because they have been subject to a range of management (felling, burning and planting) over time. More ‘ancient’ woodlands tend to contain richer associated lichens, mosses and characteristic flora. Where more commercial species or objectives exist (for example to establish trees to specific density or to maintain a set proportion of un-forked leaders), additional impacts may be measured.
Key Indicators
The key impact that deer can have are browsing on seedlings, fraying on saplings & bark stripping of mature trees. In addition, browsing can effect the structure and composition of ground-cover such a blaeberry. Information on the age, structure and condition of the woodland will indicate the timescale over which seedlings are needed to replace existing mature trees. A direct measure of deer browsing can be made on seedlings / saplings below deer browse height (approximately 1.3 m).
Other Impacts
Herbivores other than deer browse seedlings, particularly insects, rabbits, hares and voles. Factors other than herbivores (such as soils or seed viability) may also impede regeneration.
| Method |
What to measure |
What to analyse |
| Plot based approach |
The number, size and location of plots is based on area and distribution of mature trees1. Plots are circular with an area of between 0.01 - 0.05 ha (i.e. using a string of 5 - 12 m from the central post The centre of each plot is marked by a post and co-ordinates recorded by GPS.
|
Summarise the frequency of seedlings/ saplings, trees damaged by deer for each compartment.
Graph the age profile of all mature trees for each compartment. |
Within each plot record:
a. Number and species of all seedlings / saplings less than 1.3 m tall and / or less than 7 cm diameter at breast height);
b. Number and species of all trees greater than 1.3 m tall and / or greater than 7 cm diameter at breast height);
c. Number of seedlings / saplings with deer damage*;
d. Number of trees with deer damage;
e. Number of standing dead, fallen dead and tree stumps;
f. ‘Age class’ of all mature trees. |
Calculate the frequency** of leaders browsed for each species of seedling / sapling for each compartment.
Calculate the frequency of other shoots browsed for each species of seedling / sapling for each compartment. |
| Assess whether saplings have been frayed by deer * |
Average the number of saplings frayed per species per compartment |
| Assess whether trees have been bark stripped by deer* |
Average the number of saplings frayed per species per compartment |
| Marked seedlings approach |
Mark at least one seedling / sapling within each plot OR randomly select a minimum of 30 seedlings within each compartment.
Measure seedling / sapling height (straight vertical distance from ground to highest point on the seedling without lifting or stretching - see illustration above.
Assess whether the leader and other shoots on each seedling is browsed by deer (based on clean cut/ragged cut*).
|
Average the height of seedling for each compartment.
Summarise the number of seedlings/ saplings, trees and dead trees per compartment. |
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