Grasses and sedges are more resilient to grazing, i.e. more able to re-grow following grazing, than are dwarf shrubs and trees. This is because the growing points of grasses are at the base of the leaves, close to the ground, so are less likely to be removed when the plant is eaten by herbivores.
Pollock et al. (2007) asked experts how plant growth was affected by grazing. The results are summarized in Table 1 below. Table 2, at the foot of the page, outlines information collated, largely from the published literature, on resilience to grazing.
Table 1. Expert opinion on resilience to grazing of key field layer plant species |
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Group |
Species |
Phenology |
Mean plant response to grazing |
Uncertainty |
Grasses |
Common bent-grass, Agrostis capillaris |
E |
3.3 |
0 |
Grasses |
Sweet vernal grass, Anthoxanthum odoratum |
E |
3.0 |
1 |
Grasses |
Sheep’s fescue, Festuca ovina |
E |
2.9 |
1 |
Grasses |
Red fescue, Festuca rubra |
E |
2.8 |
1 |
Grasses |
Viviparous fescue, Festuca vivipara |
E |
2.7 |
1 |
Grasses |
Heath-grass, Danthonia decumbens |
E |
2.5 |
4 |
Forbs |
Wood anemone, Anemone nemorosa |
Sp-Su |
2.5 |
3 |
Grasses |
Mat-grass, Nardus stricta |
E |
2.4 |
1 |
Forbs |
Harebell, (sometimes Bluebell in Scotland), Campanula rotundifolia |
E |
2.4 |
2 |
Forbs |
Alpine lady’s mantle, Alchemilla alpina |
Sp-A |
2.3 |
5 |
Sedges |
Common sedge, Carex nigra |
E |
2.3 |
2 |
Forbs |
Heath bedstraw, Galium saxatile |
E |
2.3 |
1 |
Forbs |
Yarrow, Achillea millefolium |
E |
2.3 |
2 |
Forbs |
Tormentil, Potentilla erecta |
Sp-A |
2.2 |
1 |
Sedges |
Pill sedge, Carex pilulifera |
E |
2.2 |
3 |
Grasses |
Tufted hair-grass, Deschampsia cespitosa |
E |
2.2 |
2 |
Grasses |
Purple moor-grass, Molinia caerulea |
Sp-A |
2.2 |
1 |
Rushes |
Field wood-rush, Luzula campestris |
E |
2.2 |
3 |
Rushes |
Heath rush, moor rush, Juncus squarrosus |
E |
2.2 |
3 |
Forbs |
Bog asphodel, Narthecium ossifragum |
Sp-A |
2.1 |
2 |
Sedges |
Deergrass, Trichophorum cespitosum |
Sp-A |
2.1 |
3 |
Sedges |
Carnation sedge, Carex panicea |
E |
2.1 |
2 |
Grasses |
Wavy hair-grass, Deschampsia flexuosa |
E |
2.0 |
1 |
Forbs |
Wild thyme, Thymus praecox |
E |
2.0 |
2 |
Sedges |
Harestail cotton-grass, bog cotton, Eriophorum vaginatum |
E |
2.0 |
3 |
Rushes |
Soft rush, Juncus effusus |
E |
2.0 |
3 |
Sedges |
Green-ribbed sedge, Carex binervis |
E |
2.0 |
3 |
Sedges |
Common cotton-grass, Eriophorum angustifolium |
E |
2.0 |
3 |
Dwarf Shrubs |
Blaeberry, bilberry, Vaccinium myrtillus |
Sp-A |
1.9 |
0 |
Sedges |
Common yellow-sedge, Carex viridula ssp. oedocarpa (formerly C. demissa) |
E |
1.8 |
4 |
Dwarf Shrubs |
Bearberry, Arctostaphylos uva-ursi |
E |
1.5 |
4 |
Dwarf Shrubs |
Crowberry, Empetrum nigrum |
E |
1.4 |
4 |
Dwarf Shrubs |
Heather, Calluna vulgaris |
E |
1.4 |
0 |
Dwarf Shrubs |
Cowberry, Vaccinium vitis-idaea |
E |
1.4 |
3 |
Dwarf Shrubs |
Bell heather, Erica cinerea |
E |
1.3 |
1 |
Dwarf Shrubs |
Cross-leaved heath, Erica tetralix |
E |
1.2 |
2 |
Definitions of values used in Table 1
Phenology. ‘E’ = Evergreen, ‘Sp-A’ = Leaf canopy green Spring to Autumn, “Sp-Su” = Leaf canopy green Spring to Summer (Grime et al. 1990).
Mean plant response to grazing.High values for plant response indicate the plant re-grows well following grazing. Categories are:
1 - grazed plants grow a lot less than ungrazed plants
2 - grazed plants grow a bit less than ungrazed plants
3 - grazed plants grow the same as ungrazed plants
4 - grazed plants grow more than ungrazed plants
N.B. these values are for open hill communities, not woodlands. Individual species may respond differently in woodland shade; some species are unlikely to be encountered within woodland.
Uncertainty. The value in this column is the number of experts (out of 8) leaving the relevant question unanswered.
Table 2: Other information on resilience to grazing of key field layer plant species. |
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Common name |
Latin name |
Information |
Source |
Wavy Hair-grass, |
Deschampsia flexuosa, |
The effects of grazing and browsing on the continued persistence and abundance of particular species within the community can depend on competitive interactions with other plant species. For example Deschampsia flexuosa appears not to be heavily suppressed by grazing in scrub habitats on acid soils, possibly because of its relatively high shade tolerance allows it to retain its competitive edge….whereas in open moorland habitats its abundance is often much reduced by grazing. On the other hand, Luzula sylvatica appears to show the opposite behaviour, surviving and even spreading under moderate grazing when growing on the open hill but being much reduced by grazing in woodland and scrub. |
MacDonald (1998) |
Blaeberry/ Billberry, |
Vaccinium myrtillus, |
Vaccinium myrtillus is palatable but rhizomes provide protected buds and reserves which facilitate replacement of browsed shoots and make it slightly more resistant [resilient] to browsing than Calluna. Calluna is one of the most vulnerable dwarf-shrubs to heavy browsing pressure. |
MacDonald (1998) |
Common Bent-grass |
Agrostis capillaris |
Capable of establishing a dense low leaf canopy which under heavy grazing is rapidly renewed during late spring and early summer. |
Grime, Hodgeson & Hunt (1990). |
Cock’s-foot |
Dactylis glomerata |
Height of defoliation can be especially critical for orchardgrass (Dactylis glomerata L.), a bunch-type cool season grass that stores carbohydrate reserves for new regrowth in stem bases. |
Carlassare & Karsten (2002) |
Blaeberry, Bilberry |
Vaccinium myrtillus |
Tolerant of sheep grazing |
Grime, Hodgeson & Hunt (1990) |
Blaeberry, Bilberry |
Vaccinium myrtillus |
Vaccinium myrtillus is less tolerant of sheep grazing than grasses |
R.Thompson (personal communication) |
Yorkshire Fog |
Holcus lanatus |
Not tolerant of close grazing or heavy trampling |
Grime, Hodgeson & Hunt (2007) |
Creeping Soft-grass |
Holcus mollis |
Does not persist in heavily grazed pasture, as its few robust shoot stems are eaten more quickly than they are replaced |
Grime, Hodgeson & Hunt (1990) |
Bracken |
Pteridium aquilinum |
Trampling is an important factor reducing bracken vigour. |
MacDonald (1998) |
References
Carlassare, M. & Karsten, H.D. (2002 Species contribution to seasonal productivity of a mixed pasture under two sward grazing height regimes. Agronomy Journal, 94, 840–50.
Grime, J.P., Hodgeson, J.G. & Hunt, R. (2007) Comparative plant ecology: a functional approach to common British species. Castlepoint press.
MacDonald, A.M., Stevens, P., Armstrong, H.M, Immirzi, P. & Reynolds, P. (1998) A Guide to Upland Habitats. Surveying Land Management Impacts. Scottish Natural Heritage, Battleby.
Pollock, M. L., Legg, C.J., Holland, J.P. & Theobald, C.M. (2007). Assessment of expert opinion: seasonal sheep preference and plant response to grazing. Rangeland Ecology and Management, 60, 125-135.