D. Welch

Regeneration of Pinus sylvestris in a natural pinewood in NE Scotland following reduction in grazing by Cervus elaphus.

The occurrence of Scots pine (Pinus sylvestris L.) seedlings and saplings (<2.0 m in height and suppressed by grazing) and ground characteristics were recorded in a 300 ha block of natural pine forest in 1993. The density of red deer (Cervus elaphus L.) was then reduced by exclosure to approximately 3‐4 deer km ˇ2 , which is below the threshold at which pine regeneration should occur. Numbers and performance of pine seedlings and saplings were further monitored 2 and 4 years after exclosure. Numbers of young pine increased over time. In the three years with observations 97‐99% of pine seedlings and saplings were recorded within 20 m of a seed source. Stepwise multiple regression was used to explore the relationships of pine establishment with plot characteristics for (a) all observation plots (na 178) and (b) plots within 20 m of a seed source (na 154). The factors most closely related to the number of pine seedlings and saplings in 1997 were, for (a), seed‐source distance, vegetation height, blaeberry cover, slope and deer pellet-group density in 1993, all but the last having negative effects. For (b), vegetation height, blaeberry cover and slope were again selected predictors, and again had negative effects. Possible mechanisms by which the selected main effects may influence pine regeneration are discussed, the positive relationship to deer density being considered to reflect the creation of gaps in the sward suitable for germination. However, the amounts of variation explained in the models were low, being 16% for (a) and 13% for (b), reflecting the patchy nature and diverse age of the regeneration. # 2000 Elsevier Science B.V. All rights reserved.

A Callunetum subjected to intensive grazing by mountain hares

Summary A distinctive form of Callunetum with flat, circular bushes, radiating branch structure, and high shoot density, is ascribed to intensive grazing by mountain hares. It occurs locally in small burnt areas at moderate altitudes in north-east Scotland. At the site examined heavy hare usage was recorded over a two- year period, in which cover increased from 59 to 68 per cent, but height only from 5-1 cm to 6-4 cm. Usage by larger herbivores was negligible and exposure only moderate. Almost all shoots were grazed each year, but not all current years growth was removed, because the hares could turn to other feeding grounds once they had depleted their initial preferred grazing. It is suggested that mountain hares, unlike other herbivores, will graze out Calluna vulgaris (L.) Hull only exceptionally, because of their feeding behaviour and the densities at which they normally occur.

Trials to recreate floristically-rich vegetation by plant introduction in the Northern Pennines, England

Abstract British upland vegetation is widely regarded as floristically-impoverished owing to sheep-grazing. An account is given of the first 15 years of trials in which grazing has been removed at four contrasting grassland sites and about 30 species of plants having restricted ranges have been introduced. Vigorous growth by grasses suppressed many of the herbaceous plants, but at one site dwarf-shrubs are now increasing. Nevertheless, several of the introduced species that do not occur locally under natural conditions, have become well established, including Alchemilla alpina, Salix arbuscula, S. reticulata , and Saussurea alpina , whilst Draba incana, Polygonum viviparum, Potentilla crantzii , and Thalictrum alpinum , which occurred naturally but infrequently, have spread. Grazing is felt to be important in controlling some of these species, but Alchemilla alpina is shown to be vulnerable to competition from a dense sward of tall grasses. There is as yet little indication of which type of vegetation is climax above the tree-line; dwarf Salix scrub on the damper sites is a possibility. The effect, on the floristic richness of a site, of removing grazing, is not necessarily beneficial; but, where a whole area is grazed, increasing the number of ungrazed sites will enhance overall diversity.

Response of the moss Racomitrium lanuginosum to changes in sheep grazing and snow-lie due to a snow-fence

ABSTRACT Question: What are the responses of Racomitrium lanuginosum moss to altered snow-lie and sheep use? Location: A Carex bigelowii-Racomitrium lanuginosum heath on a Scottish montane plateau affected since 1986 by a fenced ski corridor. Methods: Permanent quadrats were set up along transects 45 m long perpendicular to the snow-fence. Cover was assessed over a 12-year period from 1990. Pellet-group clearance counts provided data on sheep usage between 1990 and 1996. Snow-lie was mapped in the springs of 1991–1996. Results: The snow-fence created a gradient in sheep use and altered the duration of snow-lie. At the start of monitoring Racomitrium cover was lower immediately adjacent to the fence, and after 12 years its cover was significantly reduced within 10 m of the fence. Further away from the fence Racomitrium cover was relatively stable. The loss of Racomitrium was correlated both with increased snow-lie and heavier sheep usage. Grass cover increased near the fence and was related to sheep use. Dicranum fuscescens responded differently to Racomitrium, increasing significantly near the fence. Conclusions: We found that changes in snow-lie and grazing pressure quickly brought about vegetation change in this montane ecosystem. Racomitrium was the most sensitive species to the changes in grazing and snow-lie caused by the fence, having the biggest initial changes. Loss of Racomitrium permitted increases of species more resistant to grazing including Dicranum fuscescens and grasses. Nomenclature: Stace(1997)for vascular plants; Smith(1978) for mosses.

Studies on the paradox of seedling rarity in Vaccinium myrtillus L. in NE Scotland

Summary On the moors studied Vaccinium myrtillus produced many berries containing highly viable seed, yet seedlings were rare. Offtake of berries by birds or mammalian herbivores was apparently minor, most berries simply falling from the bushes when ripe. Fallen berries quickly disappeared, probably being removed by small rodents. Berries were fed experimentally to captive field voles and capercaillies, and it was found that only c. 1% of the seeds survived. For the voles, most of these viable seeds probably resulted from contamination of the droppings with partially-eaten berries or discarded extracted seeds, processes which must contribute to dispersal in the wild. The soil seed-bank was shown to be small, and the viability of buried seed declined from c. 90% to c. 20% in 3 years, due to decay in the soil H horizon and premature germination in the litter layer. Fewer seedlings established from experimental sowings on grass and Vaccinium myrtillus turf than on bare peat. We conclude that Vaccinium myrtillus has a seed-dispersal strategy which secures some long-distance movement by frugivores at the expense of much lost seed, and that the small seed-bank and low numbers of seedlings result from poor defence of the seeds and weak competitive ability of the seedlings; other attributes of Vaccinium myrtillus, e.g. efficient vegetative reproduction, compensate for these losses and enable it to be a successful species.

Trends in the botanical composition of set-aside fields in North-east Scotland uncultivated for five years

Summary Species composition was monitored in 13 set-aside fields from 1989 to 1993 and in six others from 1989 to 1991. Grasses contributed more cover than dicotyledonous species throughout, but weedy species, e.g. Agrostis gigantea and Poa annua, were steadily replaced by grasses of permanent grassland, e.g. Agrostis capillaris, Dactylis glomerata and Holcus lanatus. Ranunculus repens (creeping buttercup) and Trifolium repens (white clover) became the main dicotyledonous species, and weeds characteristic of arable land had negligible cover after the first year of set-aside. As a result species richness declined, herbs of semi-natural grasslands being slow to colonize; many entrant species were recorded only in edge quadrats which extended 5 m into the fields from the headland. Noxious weeds (docks, ragwort and thistles) remained at low cover levels.

The establishment of recovery sites for Saxifraga hirculus L. in NE Scotland

Summary Work fulfilling actions and research specified in the Biodiversity Action Plan for SaxÍfraga hirculus is described. Two recovery sites have been set up in suitable mires situated within 3 km of lost sites. Seeds from two of the three remaining N. Scottish sites germinated readily, and plants were successfully propagated in a garden. Transplanting to the first recovery site began in 1996 and to the second in 2000. Transplants survived well and increased in size, with some flowering. Direct sowing of seeds to the recovery sites was less successful, with poor survival and very slow growth of seedlings. Competition from resident mire plants is thought to control the performance of the transplants, growth being most checked in hummocks of Sphagnum warnstorfii. Ideally transplants should have c. 100 cm2 basal area.

Slow recovery of heather (Calluna vulgaris L. (Hull)) in Scottish moorland after easing of heavy grazing pressure from red deer (Cervus elaphus L.)

Summary The study aimed to determine how quickly heather responds in Scottish moorland once deer grazing pressure is reduced. We monitored heather attributes and deer distribution over ten years in Glen Lui and Glen Derry, two contrasting nearby areas of it 200 ha at Mar Lodge in the eastern Cairngorms. In one area the deer received winter food, affecting the zonation of their impact. In both areas the deer were initially lightly culled, then culling was increased. Mean heather shoot utilisation was 35 % and 48 % less in the last five years of the study than initially in the two areas, and was very closely correlated with deer pellet-group counts. In Glen Lui heather cover increased significantly but height increases were small. In Glen Derry heather increased significantly in height but little in cover. We attributed the different response to the presence of a secondary grazer (rabbits, Oryctolagus cuniculus) in Glen Lui and also better conditions for heather growth on the drier soils there; rabbits grazemore delicately than deer, taking mainly the shoottips of heather and thus encourage lateral shootgrowth. In Glen Lui heather response also varied between four radial zones based on distance from the feeding grounds. At best, there was appreciable recovery four years after the easing of deer grazing pressure, but average amounts of recovery were modest.

Decline of moorland plants following the establishment of a Scots pine plantation

Summary A tract of heather (Calluna vulgaris) moorland on a brown-earth soil in north-east Scotland was planted with Scots pine in 1974, and the subsequent changes in heather and botanical composition were monitored. The pines established well and attained a mean girth of 37 cm by 1995. Before planting the moorland was heavily grazed by sheep which kept the heather short (mean height 7 cm) but with high cover (71%). After planting there have been three phases in the development of the ground vegetation. In the first eight years the heather benefited from the cessation of grazing, reaching 17 cm height and 89% coverin 1982. The cover of pine remained less than 5%, but grasses declined significantly in cover and some forbs became extinct e.g. Lotus corniculatus. In the second 8-yr phase the pine canopy closed but heather retained its dominance still having 89% cover in 1990 and a mean height of 20 cm. The main change in composition was a decline in the subsidiary dwarf shrubs (Arctostaphylos uva-ursi, Erica...

Habitat preferences and status of Saxifraga hirculus L. in North-east Scotland

Summary Six colonies of Saxifraga hirculus have been recorded in flushes and mires in north-east Scotland in the last two centuries. Populations are now known at three sites, and at a fourth a few plants of the saxifrage were seen in 1969. Vegetation composition and structure are described for the four recent colonies, and the trends in population size have been assessed. Vegetation releves were also collected from similar flushes in the district around the extant sites; stands containing the saxifrage were closely similar to stands without it. Most plants of the saxifrage grew in moderately tall vegetation dominated by Carex rostrata belonging to unit M9 in the National Vegetation Classification. But some plants grew in less tall vegetation lacking Carex rostrata; most of this was considered to belong to a community related to M9 which was designated M9o.