Dwarf shrub heath

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  • typical dwarf shrub heathland
  • signs of high impact: browsing restricted heather growth form
  • signs of low impact: few long shoots browsed, vigorous growth forms
  • measuring vegetation height in selected quadrats
  • (left) heather long-shoots unbrowsed and (right) with the top two years growth browsed
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heath
red hind
 

Aim

The aim of this guide is to describe methods of assessing Dwarf Shrub Heath relevant to deer managers.*

Habitat description

Heather moorland or dwarf shrub heath is made up of a mix of ‘dwarf shrubs’ (heathers, blaeberry, cowberry and so on) with some grasses (such as purple moor-grass and deer grass — see species list). The exact mix depends on the soil type and amount of rainfall on the area, as well as the history of burning and browsing. Heather moorland has two types: ‘dry heath’ mainly in the east with ‘wet heath’ (with more cross-leaved heath) more frequent in the west.

species
Bell Heather
Shrub. Height to 60cm. Leaves 5-7mm

 

species
Cross-leaved heath
Dwarf shrub. Height: to 60cm. Leaves 2-4 mm

 

species
Ling heather
Evergreen shrub. Height to 60cm (rarely to 1m) Leaves 1-2mm

 

 

species
Purple moor-grass
Wiry perennial often forming tussocks. Height-15-150cm. Long narrow purple spikelets 4-9 mm

 

 

species
Blaeberry
Deciduos shrub. Height up to 60cm. Leaves 1-3cm

 

species
Deer grass
5-35cm. Spikelet 3-6mm

 

Dwarf Shrub Heath species:
Ling Heather/ Calluna vulgaris
Cross-leaved heath/ Erica tetralix
Bearberry/ Arctostaphylos uva-ursi
Blaeberry/ Vaccinium myrtillus
Cowberry/ Vaccinium vitis-idaea
Crowberry/ Empetrum nigrum
Purple moor-grass / Molinia caerulea
Deer grass / Tricophorum cespitosum
Bell Heather/ Erica cinerea

Key indicators

The main impacts that deer have on dwarf shrub heath are browsing and trampling1. Browsing is measured by looking at the percentage of ‘long shoots’ of heather browsed (see illustration). This indicates the ‘off-take’. If unpalatable species such as cross-leaved heath show signs of browsing this indicates heavy impact likely to cause a deterioration in habitat condition.

Other impacts

The following factors may also have an impact on heather moorland:

  • Burning (which affects age structure2);
  • Heather beetle or mapgpie moth;
  • Other herbivores – sheep, hares, rabbits.
What to measure How to analyse
For browsing look at three or four handfuls of ling heather within each of quadrats 1, 4, 10, 13 and 16 as shown in the diagram in BPG Habitat Impact Assessment: Principles in Practice. If ling not present then use blaeberry. Look at the browsing on the long shoots and classify as:
• LIGHT: less than 33% of long shoots in the sample browsed
• MODERATE: 33 – 66% long shoots browsed
• HEAVY: greater than 66% long shoots browsed

For each plot, summarise the frequency** of quadrats in each class (for example: 3/5 quadrats “LIGHT”; 2/5 quadrats “MODERATE”; 0/5 quadrats “HEAVY” browsing.

In this example, the plot would be described as having “LIGHT” browsing as this was the class with the highest frequency.

For each site, summarise the frequency of plots in each class (for example, in a site with 30 plots: 25/30 plots “LIGHT”; 3/30 plots “MODERATE”; 2/30 plots “HEAVY” browsing.

For trampling, if plots are > 50 m away from a supplementary feeding site, assess the amount of heather stem breakage as a result of trampling and assign as classes for the whole plot:
• LIGHT / MODERATE: inconspicuous
• HEAVY: conspicuous.
For each site, summarise the frequency of plots in each class (for example,in a site with 30 plots, 14/30 plots “LIGHT/ MODERATE”, 16/30 plots “HEAVY” heather stem breakage.
For heather distribution record presence or absence of heather (or blaeberry) within each of the 16 quadrats. For each plot, summarise the frequency of quadrats with presence or absence of heather (or blaeberry) (for example: 5/16 quadrats, heather PRESENT; 11/16 quadrats, heather ABSENT).
For each site, summarise the frequency of quadrats with heather (or blaeberry) present or absent (for example, in a site with 10 plots (a total of 10 x 16 quadrats): 60/160 quadrats, heather PRESENT; 100/160 quadrats, heather ABSENT).
For vegetation height take three or four measurements with a tape measure within each of quadrats 1, 4, 10, 13 and 16.

For each plot average the height of the vegetation

Average the vegetation height for all plots.

Record presence of deer and/or hare dung in each plot. For each site, summarise the frequency of quadrats with deer dung present or absent. For example, in a site with 10 plots: 80/160 quadrats deer dung PRESENT; 80/160 quadrats, deer dung ABSENT. Repeat exercise for hare dung.
Take digital photo of whole plot from fixed point Will enable detection of changes in heather distribution over time.

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