Pollen Catchment in Relation to Local Vegetation: Ceann Ear, Monach Isles N.N.R., Outer Hebrides

Randall, R. E.; Andrew, R.; West, R. G.

doi:10.1111/j.1469-8137.1986.tb00651.x

Cited by 23 publications

(31 citation statements)

References 12 publications

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“…Alternatively, unique wind and pollen dispersal patterns on small, unforested islands may lead to pollen deposition patterns unrelated to vegetation patterns. We view this hypothesis as less likely, however, in view of the clear local signals obtained from island moss polsters by Randall et al (1986).…”

Section: Pollen Representation and Dispersal On Block Islandmentioning

confidence: 78%

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Pollen dispersal and representation on an offshore island

Jackson

Dunwiddie

1992

New Phytologist

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SUMMARYThe effects of spatial isolation on pollen representation were examined in a study of seven small kettle ponds on Block Island, a small, unforested island 19 km off the New England Coast (USA). Modern pollen assemblages from the ponds were compared with modern assemblages from similar ponds on the adjacent, partly forested mainland and in extensively forested northern New York. Representation of pollen from local and extralocal sources was amplified on the island owing to spatial isolation. However, variation among pollen assemblages on the island was not clearly related to spatial variation in vegetation composition. Significant transport of pollen from the mainland to the island was observed. There appeared to be little or no decrease in representation of large, poorly dispersed mainland pollen types between the mainland and island. This latter result may indicate difTerences between the mainland and island in the predominant modes of pollen transport, or alternatively, effects of local pollen source strength on representation of pollen from distant sources. Based on our results, we propose a theory of pollen representation on islands that can be tested and applied on offshore islands and patchy landscapes.

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Section: Pollen Representation and Dispersal On Block Islandmentioning

confidence: 78%

“…However, Berglund (1973) and Randall, Andrew & West (1986) have shown how offshore islands can be used effectively to study pollen dispersal and to differentiate local and nonlocal pollen sources.…”

Section: Introduction Broadening the Applications Of Pollen Analysismentioning

confidence: 99%

Pollen dispersal and representation on an offshore island

Jackson

Dunwiddie

1992

New Phytologist

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“…Both pollen production and pollen dispersal may be influenced by land-use practices (e.g. Moore et al 1986;Randall et al 1986;Groenman-van Waateringe 1993). The time of flowering in relation to mowing, whether grazing occurs during the whole season or only during parts of it, as well as animals' preference for one taxon from another, will influence the amount of pollen deposited.…”

Section: Discussionmentioning

confidence: 99%

“…Little is known about the representation of herbs in pollen assemblages, although some scatter plots which show the relationships between pollen and plant percentages have been published (e.g. Davis 1984;Berglund et al 1986;Moore et al 1986;Randall et al 1986;van der Knaap 1990), and R-values (Ritchie 1974) as well as plant to pollen representation (Heim 1970;Caramiello et al 1991) have been estimated.…”

Section: Introductionmentioning

confidence: 98%

Herb pollen representation in surface moss samples from mown meadows and pastures in western Norway

Hjelle

1998

Veget Hist Archaebot

108

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Abstract. Grazed relative to Poaceae (Rl) are calculated for 54 pollen taxa. Differences in the values from different geographical areas were found in the case of some taxa, due to either different genera or species being included in the pollen taxa and/or to the different representation of high pollen producers in the different regional vegetation types. Background pollen influences the estimates for taxa such as R. sect. Acetosa, P. lanceolata, Poaceae, Cyperaceae, and Calluna, and an extended R-value (ERV) model was used to investigate the magnitude of this pollen component. Groups of roughly similar pollen representation were identified and factors to convert pollen percentages to vegetation abundances are suggested.

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“…Pollen accumulation rates at these levels are low for forested regions, and high for unforested areas, but are typical of landscapes with mixtures of forested and nonforested units, or 'forest tundra' (Birks & Birks, 1980). A hypothesis that the tree pollen rain at Loch Lang during the post-glacial is due to long-distance transport of pollen from the Scottish mainland can be rejected because: (1) the proportion of tree pollen, at up to 60",, of total pollen, is higher than would be expected if all the tree pollen found had been blown from the Scottish mainland (at present only l'6"b of the pollen rain on the Monach Isles, west of North Uist, is from ofl'-island taxa [Randall et al, 1986]); (2) accumulation rates for tree pollen are high, lO'-UV times higher than annual long-distance transport of tree pollen to Shetland (Tyldesley, 1973); (3) there is no en-hancement of proportions of pollen types known to be dispersed long distances (such as Pinus); (4) macrofossil remains of trees have been found in the Western Isles (Wilkins, 1984; K. J. Edwards, pers. comm.…”

Section: Early Postglacial Woodland Historymentioning

confidence: 99%

Holocene vegetational and environmental history at Loch Lang, South Uist, Western Isles, Scotland

et al. 1990

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A Holocene record of pollen, charcoal, magnetic susceptibility and sediment chemistry from South Uist, Western Isles, IS described and discussed. The vegetation of eastern South Uist included areas of woodland over as much as half of the available landscape during the early postglacial. This woodland was dominated by Betula and Corylus, but Quercus, Ulmus, Alnus glutinosa and Fraxinus excelsior were also present. The status of Pinus sylvestris IS uncertain. Quercus, Ulmus and A. glutinosa are now extinct as native trees in the Western Isles. During the later half of the Holocene (from about 4000 BP), woodland declined, possibly as a result of the use of hill land as grazing. Blanket peat vegetation, which had begun to spread from about 5500 HP, became the dominant feature of the landscape as the woodland areas decreased. The physical and chemical data from Loch Lang sediments suggest that little erosion of soils took place until about 550 years ago, when there vvas a marked increase, possibly attributable to increasing grazing pressure. Key words; Holocene, vegetation history, radiocarbon dating, sediment chemistry. Western Isles. INTRODUCTION°^ bedrock geology, and the treeless aspect of the Western Isles relative to the mainland at the same he Western Isles of Scotland, lying on the latitude has been explained by their greater degree of northwestern fringe of Europe and exposed to a wet exposure to wind. This introduces a strong east-west ana windy oceanic climate, are today virtually gradient to syntheses of Scottish vegetation (e.g. treeless. Their landscape is, for the most part, during the historical period [McVean & Ratcliffe, aominated by blanket peat up to several metres 1962] or at 5000 BP [Bennett, 1989], Is this view of t ick. The islands extend nearly 190 km from north the Western Isles supported by palaeoecological to south, from the latitude of Fort William to that of data? In the only modern works on the Holocene ape Wrath. Perhaps because they form a discrete vegetation history of the Western Isles, Birks & geographical unit, there has been a tendency to treat Madsen (1979) suggested that at least western Lewis e islands as uniform in vegetational terms, had been mostly treeless throughout the Holocene. a though the same latitudinal extent on the west Bohncke (1988) argued that the Callanish area, also cottish mainland coast covers a range of vegetation in western Lewis, supported local Betula woodland ypes from oak-dominated woodlands, through pine that was severely affected by anthropogenic burning, and birch to generally unforested areas of the Wilkins (1984) has drawn attention to the abundant northwest mainland. The vegetational richness and macrofossil remains of trees, including at least one variety of Skye, entirely within the latitudinal range species now extinct as a native tree in the Western o the Western Isles, are well-documented (e.g. Isles {Pinus sylvestris), within the blanket peat of irks, 1973). At least in part, there may be a Lewis and Harris. The palaeoecological and hisve...

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Pollen Catchment in Relation to Local Vegetation: Ceann Ear, Monach Isles N.N.R., Outer Hebrides

Cited by 23 publications

References 12 publications

Pollen dispersal and representation on an offshore island

Pollen dispersal and representation on an offshore island

Herb pollen representation in surface moss samples from mown meadows and pastures in western Norway

Holocene vegetational and environmental history at Loch Lang, South Uist, Western Isles, Scotland

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