Abernethy Forest Research Articles

Timing of shedding seeds and cones, and production in different stands of Scots pines at Abernethy Forest, Scotland

Summary A study was carried out over 11 seed years on the timing of shedding of seeds and cones, and annual seed fall and cone production in three stands of native Scots pinewood and a Scots pine plantation in Abernethy Forest, Scotland. Peaks in seed fall took place mainly in May, and cones were shed mainly between June and August. There were few residual seeds remaining in shed cones. Synchronized peaks in seed fall and cone production (mast years) took place at 3-year intervals across the different stands. The difference between cohorts of high and low cone production ranged from factors of 5 to 20 among sites. Coeffi cients of variation for cone production ranged from 62 to 84 per cent among sites. There were no signifi cant differences in cone production among sites, but there were site-related differences in seed fall. The larger canopy cover in the plantation probably accounted for the higher seed fall per square metre there, though variations in the amount of seed eaten by birds and mammals may also have been important. Canopy cover needs to be considered when converting cone densities under crowns to cone density per unit of woodland area. A similar calculation is diffi cult for seeds because they are lighter than cones and many fall outside the area under the crowns. The results are discussed in relation to the potential for tree regeneration and the availability of food for birds and mammals prior to seed dispersal.

The effect of experimental prescribed fire on the establishment of Scots pine Pinus sylvestris seedlings on heather Calluna vulgaris moorland

A key management objective for native Scots pine ( Pinus sylvestris) forests in Scotland is to extend the forest onto treeless moorland, below the natural tree line, dominated by the dwarf shrub, heather ( Calluna vulgaris). At Abernethy Forest, Scotland's largest native pinewood remnant, establishment of new tree seedlings on moorland has recently slowed despite the low grazing pressure. To investigate whether fire would be a useful management tool to improve the rate of regeneration of Scots pine, an experiment was carried out in 10 plots, on open moorland, on shallow peat soil, c 300 m from the forest edge. At each plot, 10 small exclosures were established, two for each of four burning treatments, and two controls. Within each exclosure, 100 Scots pine seeds were sown and the numbers of seedlings resulting were counted after 2, 11 and 30 months. Exclosures substantially reduced seed and seedling predation by mammals and invertebrates. The four burning treatments were single and double burns in the year of sowing, and single and double burns 1 year before sowing. Single burns removed largely heather, whilst second burns removed more of the moss. Burnt areas had 3.5 times (95% confidence limits 1.5–8.1) the number of seedlings established as controls, 2 months after sowing. There was no significant additional effect on seedling numbers of either double burning or year of burn. Slower-moving fires and, to some extent, shallower post-fire moss/litter depths, were associated with more seedlings establishing. Seedling numbers declined by 18% between months 2 and 11 and by 27% between months 11 and 30. The pattern of these declines was not significantly affected by treatment, post-fire moss/litter depth, or fire characteristics. The results have wide application at sites where Scots pine regeneration is a management aim, particularly on heather moorland, and where techniques which mimic natural processes are preferred. Managers at such sites should include prescribed burning, in conditions that produce slow-moving fires and shallow post-fire moss/litter depths, as a management option for improved Scots pine seedling establishment.

Use of pine snags by birds in different stand types of Scots Pine Pinus sylvestris

Capsule Hole-nesting birds tended to breed in the largest pine snags (standing dead trees) predominating in ancient native pinewood and scarce in plantations. Aims To describe and compare the density, volume and sizes of pine snags in different stands of ancient native Scots Pine wood and Scots Pine plantations at Abernethy Forest, and to determine the use made by hole-nesting birds in such stands. Methods The status of snags in different stands was based on samples taken along random transects through the forest. Nests were also searched for along the transects and combined with incidental data. Results Mean snag densities were 15–102/ha, volumes 1.8–28.7 m3/ha, and median diameter at breast height (DBH) 9.2–19.3 cm in different stands of ancient native pinewood. Snag densities were 9–275/ha, volumes 0.4–7.5 m3/ha and DBHs 3.8–9.6 cm in different plantation stands. From this available resource, Great Spotted Woodpeckers Dendrocopos major and Crested Tits Parus cristatus selected the larger snags for excavating nest and roost sites, primarily in ancient native pinewood. Several birds (Swift Apus apus, Wryneck Jynx torquilla, tits and Redstart Phoenicurus phoenicurus) were secondary occupiers of woodpecker excavations. Ducks, Tawny Owl Strix aluco and Kestrel Falco tinnunculus also used holes in large snags for nest sites. It is thought that the main cause of tree death is stem exclusion resulting in relatively few large snags, the sizes that birds prefer. Conclusion Forest and wildlife managers should consider killing some large pine trees (over 40 cm DBH) in plantations where other wildlife interests are not compromised, and thereby provide suitable snags for birds and other wildlife.

An experimental study of the effects of predation on the breeding productivity of capercaillie and black grouse

Summary The capercaillie Tetrao urogallus and black grouse Tetrao tetrix are declining in the UK, and low breeding success has been identified as the key factor in the decline of the former. To investigate possible causes, breeding productivity was studied in relation to predation, weather, vegetation changes and deer numbers over an 11‐year period (1989–99) within native pinewood at Abernethy Forest, Scotland. The abundance of predators (crows Corvus corone and red foxes Vulpes vulpes) was experimentally manipulated in 1992–96 by culling. Productivity (chicks reared per female) was compared between forests with and without experimental predator management. During predator control, the number of breeding crows was reduced from 10 pairs to one. The attempted reduction in red fox abundance was unsuccessful; only small numbers of adults were killed, and neither scat nor den counts declined significantly. Predation on artificial nests containing six hen eggs and a hen egg filled with wax was measured as an index of predator activity from 1991 to 1999. Predation was lowest during the last three years of predator control, 1994–96. Predators could sometimes be distinguished by signs on depredated eggs. Predation on artificial nests by crows was highest during 1991–93. However, after predator removal stopped in 1997 few crows returned, and increased predation on artificial nests did not involve increased signs of crow predation. Pine marten Martes martes numbers increased during the study period and became significant predators of artificial nests. The total number of capercaillie eggs and nests depredated by crows was estimated from the number of depredated capercaillie eggs found and the proportion of crow‐predated hen eggs in artificial nests. The values ranged from 18 to 158 eggs over 3 years, equivalent to 3–23 capercaillie nests year−1. Capercaillie productivity was low (< 1 chick per female) during 1989–93 and 1997–99 but higher during 1994–96. Compared with nine other forests in Scotland, changes in capercaillie productivity at Abernethy were different. Productivity at Abernethy was negatively related to June rainfall, and to the minimum daily predation rate on artificial nests by crows. There was also a significant interaction in that capercaillie were most productive when low rainfall coincided with low predation by crows on artificial nests. The productivities of black grouse and capercaillie were positively correlated, but greater in the former. As in capercaillie, black grouse productivity was negatively related both to June rainfall and the minimum daily predation rate on artificial nests by crows, and there was an interaction. Synthesis and applications. The long‐term increase in crows and red foxes and the predicted increase in rainfall in Scotland may have negative effects on capercaillie and black grouse. In the short term, control of crows is likely to improve productivity. In the long term, increased woodland size and some reversal of fragmentation might decrease the access to woodland of predators associated with the interface between farmland and woodland.

Diversity of fungi in organic soils under a moorland – Scots pine (Pinus sylvestris L.) gradient

The conservation and regeneration of native Scots pine (Pinus sylvestris L.) woodlands is being actively encouraged by conservation agencies in the UK because of their high biodiversity value. In the present study, the consequences of regeneration on terrestrial fungal communities was determined in three parallel transects running from open moorland, through an intermediate zone showing seedling colonization, into a mature Scots pine forest at Abernethy Forest, Cairngorm, Scotland. Soil cores were taken at 18 m intervals along each 180 m transect, and the diversity of the soil fungal community was investigated by DGGE and sequence analysis of ITS fragments PCR-amplified from DNA extracted from soil. Analysis of DGGE profiles generated for two of the three transects indicates a clear shift in the community from the moorland region of the transects to the forest region. Whereas a few bands were present at all sampling points across the transects, the majority of bands were unique to either the moorland or forest samples. FASTA database searches of ITS sequence data generated from excised DGGE bands revealed the closest species match for each band. In some cases, the similarity of ITS sequences to database sequences was poor, but the remaining sequences were most closely related to ITS sequences of both mycorrhizal and non-mycorrhizal fungi. The data are discussed in relation to the effect of native pine woodland expansion on the soil fungal community.

Native woodland expansion: soil chemical and microbiological indicators of change

The regeneration of native pine woodlands, a habitat of high biodiversity value, is being actively encouraged by conservation agencies as a positive future change in land use. A field study was carried out at Abernethy Forest, Scotland by sampling soil along three parallel transects running from open moorland, through an intermediate zone showing tree seedling colonization, into mature native pinewood forest with the aim of establishing a long-term monitoring site and providing baseline data. The specific objectives were to determine, first, which physical, chemical or microbiological properties in moorland soils would be affected by tree colonization and, secondly, what might be the implications of forest expansion on the soil carbon balance. Moving from moorland to forest, moisture and soil acidity decreased significantly and paralleled vegetation changes but there was little change in %C or %N. Microbial biomass, measured as the total carbon in the soil microflora, decreased markedly towards the forest while the metabolic quotient, a relative measure of microbial activity, showed a significant increase. None of the chemical or microbial indicators were able to detect changes due to seedling colonization at their present stage of development. However, microbial indicators appeared to be more sensitive than physico-chemical properties to the aboveground vegetation. Both the microbial biomass C and the metabolic quotient are likely to be good indicators of change as colonization develops. Estimation of the total sequestered soil carbon indicated more in the moorland (524 t C ha −1) than in the forest (288 t C ha −1), but this did not include the modest aboveground carbon stored in the tree biomass. At this particular site, forest expansion may result in some loss of soil C that would be partly offset by increases in aboveground C.

Contexts, developing ideas and emerging issues in the conservation management of the RSPB Abernethy Forest Reserve

Summary Native pinewoods are fragmentary in extent and floristic integrity. In maintaining and extending these remnants, managers should recognise the diversity of potential communities and the unique mix of species in their flora. At the RSPB Abernethy Forest Reserve management aims to develop a self sustaining forest of natural character over the potential woodland area. A present-natural forest provides one model for the attributes and processes, which this forest should contain. Habitat management experiments have recently commenced investigating ways of increasing blaeberry Vaccinium myrtillus in forest areas, and increasing tree regeneration at the forest edge. The possible wider role of management intervention in pinewoods is discussed.

Nest-site selection by crossbills Loxia spp. in ancient native pinewoods at Abernethy Forest, Strathspey, Highland

Capsule Birds preferred stands with a particular density of trees, perhaps to avoid predation, and they selected aspects sheltered from prevailing winds. Aim To describe the nesting habitat and tree selection by crossbills in a restricted pinewood habitat in Scotland. Methods Scots Pines used by nesting crossbills were described and compared with randomly selected pines. Nest aspect was related to wind strength and direction. Results The crossbills selected trees at a density of 50–60 trees/ha. Such stands may be sufficiently dense to provide cover, yet occur at a low enough density to minimize being visited by potential arboreal predators, such as Red Squirrels and Pine Martens. Crossbills tended to nest on lateral branches on the northeast side of crowns. Tree crown development was not asymmetric, so the birds may choose the northeast side to shelter from the prevailing southerly to westerly winds. Conclusion Stands of pines at a low density need to be maintained for the benefit of crossbills.

Scots pine growing on forested mires in Abernethy Forest, Strathspey, Scotland

Summary A substantial proportion of the Abernethy Forest Reserve has Scots pine (Pinus sylvestris) growing on the surfaces of a variety of mires. The hydrology of the mires has been affected by drainage and peat cutting but this area is unusual in having had a long period of protection from grazing by domestic stock. There are three main types of pine populations found on these mires. Woodland bog comprises predominantly bog vegetation with abundant pine seedlings due to the heavy seed rain from the surrounding woodland. Only a few very small trees survive, which are stunted, heavily diseased and have very low seed production. Wooded bog also comprises predominately bog vegetation but there are scattered mature trees of a moderate height with an open canopy. The trees are fertile and can form uneven aged stands with regeneration. Bog woodland is a predominantly woodland vegetation with tall, dense tree cover on deep peat. The trees are well grown with a dense canopy. A few remnants of bog vegetation remai...

FTIR spectroscopy of peat in and bordering Scots pine woodland: relationship with chemical and biological properties

Rapid methods of analysis, such as infrared spectroscopy, have advantages where chemical or biological analyses are time-consuming or require fresh material. FTIR (Fourier transform infrared) spectroscopy gives information on specific functional chemical groups present in organic matter. However, the whole spectrum may also contain information that relates to more general chemical or biological properties. Peat samples were taken along a transect from moorland, through a wetter bog area, into native pine at Abernethy Forest, Scotland. FTIR spectra were determined in addition to other chemical, physical and microbiological properties. Canonical variate analysis showed that the FTIR spectra of the peat from three major vegetation zones were significantly different. Partial least squares (PLS) analysis gave a good correlation between the zero-order FTIR spectra and physical/chemical properties such as pH (variance accounted for, r 2=78%), ash ( r 2=69%) and total N ( r 2=60%). In particular, the regions in the spectrum corresponding to two secondary amide groupings explained much of the variation in total N. Correlations with biological parameters were poorer except for microbial biomass C ( r 2=75%) and total phospholipid fatty acids ( r 2=65%). However, the PLS models were not suitable for predicting the chemical and microbiological properties of the moorland and forest peat soils investigated in this study reliably.

A comparison of pinewood and moorland soils in the Abernethy Forest Reserve, Scotland

AbstractDespite considerable published literature on the above‐ground ecology of the pinewoods of Scotland, little research has considered the way in which pinewood soils differ from those under other vegetation types. Soil properties were compared between ancient, semi‐natural Scots pine forest and moorland on three soil types in the Abernethy Forest Reserve in the Cairngorm Mountains of Scotland. Soil morphology differed considerably between the vegetation types on each soil type, principally in the thickness of organic layers. Forest soils had thicker organic layers and this was particularly true of the F horizon. Forest soils were slightly less acid than equivalent moorland soils and had accumulated significantly more carbon. Forest soils in this environment therefore have the capacity to sequester larger amounts of carbon than moorland, and therefore represent a significant potential carbon sink. The quantity of nitrogen and phosphorus was also consistently larger in the organic layers under pine forest and since little difference existed in these properties in the mineral horizons, it was concluded that this accumulation was real and represented a net addition to the tree‐soil system.

Changes within oribatid mite communities associted with Scots pine regeneration

Abstract. Compositions of oribatid mite communities were compared under five stages of native Scots pine regeneration (spanning 100 yr) within the Abernethy Forest Reserve, U.K. Sampling was conducted during autumn and spring, and oribatid mites identified using the morphospecies technique. Results showed the oribatid mite fauna to be abundant and diverse. Density of mites generally decreased with soil depth, however in the woodland sites the upper 10 cm of soil contained more individuals than the litter layer. Eleven morphospecies showed significant differences (p < 0.05) in abundance between sites, with marked preferences shown for either mature woodland or tree-less moorland. During spring, morphospecies richness and mite density were highest at the woodland sites, but during autumn they were greater at the moorland sites. Shannon Wiener diversity indices and measures of evenness, calculated for each site, showed that despite having a high morphospecies richness, sites were often dominated by a few very abundant morphospecies. A greater number of mites were collected during autumn, but only one morphospecies showed significant seasonal differences in numbers. Factors influencing differences in oribatid communities at each site are discussed and the use of morphospecies as an identification tool is also assessed.

Tree and cone selection by crossbills Loxia sp. and red squirrels Sciurus vulgaris at Abernethy forest, Strathspey

Tree and cone selection by crossbills and red squirrels foraging on Scots pine in winter at Abernethy Forest were described from the distribution of predated cones dropped under trees. Crossbills and red squirrels fed in different parts of the forest. These distributions were related to differences in tree size, shape and density. Crossbills preferred taller, larger trees with broader crowns; these were growing at a low density. In contrast, red squirrels preferred tall trees with short crown depth and growing at a high density. Two hypotheses are put forward to account for tree selection by these species. Selection may be related to predator avoidance. Widely-spaced old trees may provide crossbills with better all-round visibility. In contrast, red squirrels may prefer denser stands where there is less need to come to the ground to cross between trees. Alternatively, crossbills may prefer old, large trees because they have smaller cones. Although smaller cones have fewer and slightly smaller seeds than the larger ones, they still may be more profitable for crossbills because their scales are easier to prise open. Red squirrels are about six times heavier than crossbills and tear or cut into cones with sharp incisors, so probably have less difficulty in opening large cones. The differing preferences for trees and cones by red squirrels and crossbills in native Scots pine forests probably reduces competition, whilst annual fluctuations in the cone crop from area to area may allow the competitively inferior, but more mobile crossbills, to avoid competitive exclusion.

New and Interesting Agarics from Abernethy Forest, Scotland

Summary. Three new species of agarics are described: Hypholoma fulvidulum, Russula xenochlora and Tricholoma sciodellum, and descriptions are given of British material of Leptonia atrocaerulea (Noordel.) P. D. Orton and Nolanea inutilis (Britzelm.) Sacc. & Trotter all from Abernethy Forest, Scotland. A revised key to the sciodes group of 7Ticholoma is provided. Lamellae adnate vel leviter emarginatae, e pallide flavis vel citrinis viridulae vel ochraceae dein pallide argillaceo vel olivaceo umbrinae, subconfertae, ad aciem integrae concoloratae vel leviter pallidiores. Stipes 16 - 62 x 0.5 - 1.5 mm, aequalis saepe ad basim leviter incrassatus, ad apicem cremeus vel flavo cremeus infra lateritius vel ferrugineus, ad basim fere umbrinus, glaber, opacus, primo disperse + fugace sericeo-fibrillosis floccosis maculis obtectus, ad basim pallide cremeo tomentosus, primo admodum lentus. Caro concolorata siccitate cremea vel pallide luteolobrunnea. Odor nullus. Sporae 8 - 10.5 x 5.5 - 6.5 pm ad faciem conspectu ellipsoideae vel ovato-ellipsoideae, oblique conspectu ellipsoideo amygdaliformes, poro germinativo interdum vix manifeste (Fig. IG), sub microscopio aliquantum pallidae, in cumulo argillaceo-violaceae. Basidia 4-sporigera, circa 30 x 7 - 8 pm.

The structure of Abernethy Forest, Strathspey, Scotland

Summary The woodland within the Royal Society for the Protection of Birds (RSPB), Abernethy Forest reserve currently extends over c. 28 km2. One third is plantation and two thirds (c. 19 km2) is native forest, representing one of the largest remnants of the Caledonian forest that once covered much of Highland Scotland. The Scots pine Pinus sylvestris L. is the most abundant tree. Structure was described according to two principal component scores, allowing characterization of the forest into stand types. In the lower, north-west part, plantations and wooded bogs predominate. In the plantations, the treesare younger and grow at a higher density than in the native forest. The upper, south-east section of the forest is composed largely of native pinewood; either old trees with deep crowns growing at a low density or high crown trees at a higher density. Different rates of recruitment, perhaps associated with fire may have led to these two stand types. In the last 100 years, selective felling has exaggerated ...

Nest site selection, management and breeding success of Crested TitsParus cristatusat Abernethy Forest, Strathspey

Crested Tits at Abernethy Forest RSPB nature reserve selected broad stumps and dead trees of Scots Pine in which they excavated nest chambers in the rotten sapwood of the trunks. Given the size requirements for nest chambers, only trees with a diameter greater than about 20 cm are suitable, as sapwood depth is correlated with trunk diameter. There was avoidance of the south-west quadrant of dead trees and stumps, despite the greater depth of soft sapwood on the west side of dead trees. Prevailing weather or sunlight may affect aspect selection. Nests occurred in old open forest and plantations where the density of the surrounding trees averaged 290 per ha. Mean clutch size was 5.5 eggs and nest success was 50%. The provision of potential nest sites by cutting ‘high’ stumps has shown that it takes about nine years for the sapwood to rot sufficiently for excavation. However, none has been used to date, perhaps because of the small trunk diameters. It is recommended that future stumps should be cut at least ...

The use of Rarefaction Analysis for Estimating Palynological Richness from Quaternary Pollen-Analytical Data

Reconstructing temporal changes in diversity from pollen assemblages is potentially important both palaeoecologically and ecologically because community diversity may, in part, result from historical processes. The use of diversity indices such as Shannon's information index or Simpson's index is not appropriate with pollen percentage data because such indices consider both the numbers of different taxa and their relative frequencies or representation. The latter aspect in pollen data is inevitably influenced by inherent differences in pollen production and dispersal. The total number of taxa present in a sample is a robust and useful measure of palynological richness if, and only if, all the pollen counts are standardized to a fixed number of grains. Rarefaction analysis implements such a standardization and provides minimum variance unbiased estimates of the expected number of taxa ( t) in a random sample of n individuals taken from a larger collection of N individuals containing T taxa. The underlying mathematical theory of rarefaction analysis and its important biological and palaeoecological assumptions are discussed. The use of rarefaction analysis is illustrated with three data-sets: Crose Mere, central England (0-c. 12 500 BP); Abernethy Forest, eastern Scotland (5500-12 100 BP); and three sites (Lochs Ashik, Cleat, Meodal) on the Isle of Skye, western Scotland, all covering the last 10 500 years. Palynological richness, as estimated by rarefaction analysis, is high in the protocratic phase (c. 9500-12 500 BP), low in the mesocratic phase (c. 5500-9500 BP), low in the oligocratic phase (0-c. 5500 BP), and high in the Homo sapiens phase (0-c. 5000 BP) of the Holocene. Although factors such as local site characteristics and pollen production, dispersal, and input may influence temporal changes in richness, changes in palynological richness are interpreted as reflecting predominantly the changing floristic richness of the vegetation types in the pollen-source area of a lake and the changing mosaic structure of the landscape through time. Intermediate levels of disturbance, either natural in the protocratic phase or anthropogenic in the Homo sapiens phase appear to be important in maximizing richness at the landscape scale by preventing (he dominance of any single component but insufficient to cause extinction of components at the landscape scale.

Native pinewood soils in the northern section of Abernethy forest

Abstract The morphological and environmental characteristics of the dominant soils, iron and humus iron podzols, found within the northern section of Abernethy Forest, are discussed along with their possible variation in profile morphology and their analytical properties. Beneath a native pinewood, the humus iron podzol subgroup is widespread, but other podzol subgroups, peat and peaty gleys are also to be found. Considerable significance is attached to the studies in relation to future ecological studies and to the management and conservation of native pinewood habitats, both in Speyside and throughout Scotland.

Studies IN THE VEGETATIONAL HISTORY OF SCOTLAND

SUMMARYThis paper describes palaeoecological studies at Abernethy Forest by means of pollen and macrofossil analysis and radiocarbon dating. It also illustrates the value of stratigraphic macrofossil analysis in conjunction with pollen analysis in increasing the range and detail of palaeoecological reconstructions of past vegetation and environment.A new, large diameter core from Abernethy Forest was radiocarbon dated, and the presence of Late Devensian sediments was confirmed. Clear vegetational changes were recorded. A pioneer grass‐sedge vegetation colonized the bare moraine. It developed into a shrub tundra, dominated by Empetrum and Be tula nana as a result of the climatic warming during Allerød time. The Younger Dryas climatic deterioration led to the formation of species‐rich open vegetation, in which Artemisia was very abundant.At the opening of the Flandrian, at about 9700 B.P., Juniperus and Betula nana scrub developed, which was later colonized by tree Betula and then Corylus. From about 7225 B.P. Pinus dominated the forest.Throughout, the specific determinations and local derivation of macrofossils enhanced the reconstruction of the upland vegetation. In addition, macrofossils provided the majority of the evidence for the progression of the hydrosere through lake to bog communities.The complementary nature of pollen and macrofossil analyses from the same core is emphasized by a direct comparison of seed and pollen influxes.

A re-interpretation of the deglaciation of Abernethy Forest, Inverness-shire

Synopsis Field investigations of the Abernethy Forest area, including large-scale geomorphological mapping, show that ice sheet wastage has produced meltwaters that have eroded and deposited sequences of fluvioglacial landforms whose patterns reflect the local topography and changing condition of the wasting glacier ice. Successively lower drainage outlets were utilised as the meltwaters sought out the most direct escape routes. Marginal drainage was never widespread and there is no evidence of former ice-dammed lakes.