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Even when Pinus is dominant, other taxa continue to grow with it, forming the local assemblage. Though the difference between the 2990 species of British vascular plants (Stace 1991) and the 390 types of pollen and spores following the same

taxonomy and nomenclature (Bennett 1996, vad Odgaard 1999) is still apparent, developments in pollen taxonomy have helped improve definition of plant

assemblages. The series „The North West European Pollen Flora‟ includes Betulaceae and Corylaceae (Blackmore et al. 2003) and Myricaceae (Punt et al. 2002) while Foss and Doyle (1988) represents an earlier improvement within the Ericaceae. Better definition of the source of identified taxa has also improved definition of assemblages (Section 2.6.2).

Birks‟ (1972) Loch Maree study is taxonomically „cautious‟, using

combinations of Betula, Betula/Corylus/Myrica and Corylus/Myrica, to show birch- hazel woodland prior to the appearance of Pinus. At Loch Sionascaig and Loch Craggie, pine or pine–birch woodland also replaced birch–hazel woodland

(Pennington et al. 1972). Pinus at nearby Loch Clair expanded into a “herb and fern rich birchwood, with much willow, and low percentages of hazel” (Pennington et al., 1972, page 280). Oak and especially alder became important in the Loch Maree assemblage during the mid Holocene, but neither formed a sizable component in other areas. When Pinus woodland began to decline Betula remained important, with Calluna vulgaris forming heathland between fragmenting patches of woodland.

At Binney‟s (1997) Beinn Dearg site, Betula remained present after Pinus replaced it as the dominant taxon. Binney (1997) suggests that Pinus was able to establish in canopy gaps as Betula density decreased during a period of drying

conditions. During the mid-Holocene, change between Betula woodland, Pinus woodland and heath took place in response to regional environmental change.

East Glen Affric is shown by Froyd (2005) and Shaw (2006) to have had a continual presence of Pinus from c. 9600 cal BP to the present. Shaw‟s sites were chosen to emphasize local vegetation and stratigraphies are dissimilar, with mixed woodland and cycling between woodland and heath more common than stable Pinus- dominated woodland (Shaw 2006). Pinus is more consistently present at the east end of the glen. At the furthest west of her sites, Torran Beithe, Davies (2003a) found that initially Pinus co-existed with Betula-Sorbus-Populus communities. Pinus became the dominant taxon by ousting both Populus and Sorbus, but Betula remained. Later rapid replacement of Pinus (see below,Section 2.6.9) by Quercus, Alnus and Corylus suggests they were already present at low densities in the area. Herbaceous and heath taxa became more important after c. 3890 cal BP.

The oldest of Shaw‟s (2006) sequences, PB, is in mid Glen Affric (Shaw 2006). At the base (c. 5260 cal BP) the pollen assemblage consists of 50% Pinus (with stomata) confirming woodland with Betula, Ulmus and other trees. During declines in Pinus (from c. 4500 cal BP) woodland remained diverse with Betula and possibly Alnus and Quercus. Remnants remained until c. 2500 cal BP. Two sequences further east (ANI and ARC) are no older than c. 3770 cal BP, but show almost

continual local Pinus presence, in agreement with Froyd‟s (2005) sequence at Loch an Amair. The arboreal associations for these cores are less varied than further west. Betula is the main secondary taxon, but Quercus is also evident. There is good evidence of woodland / heath cycling. Furthest east three cores indicate more stable woodland over the last c. 4000 years. Pinus dominates with Betula, Calluna and latterly Poaceae.

On the west side of the Cairngorms, Birks (1970), O‟Sullivan (1974a, 1976), and Birks and Mathewes (1978) agree that Pinus woodland invaded a landscape dominated by Betula-Corylus woodland (O‟Sullivan 1974a, Birks and Mathewes 1978). At Abernethy Forest Birks and Mathewes (1978) use a combination of macrofossil and pollen evidence to show that increasing Pinus percentage probably indicates Pinus woodland replacing Betula and Corylus. The assemblage zones are in agreement with Birks (1970) undated sequence also from Abernethy Forest. Neither sequence is younger than mid-Holocene.

At Loch Pityoulish, O‟Sullivan (1976) agrees that Betula continued to be important after Pinus became dominant. When Pinus declines after c. 5700 cal BP, the main replacements are Betula and Quercus rather than Juniperus and Calluna. In the mid to late Holocene as Pinus continues to decline, substitution of Pinus by Betula continues, with Alnus and NAP becoming important only after c. 900 cal BP.

Pinus pollen in the Loch Garten sequence increases to more than 60% TLP (O‟Sullivan 1974a) at the expense of Betula and Corylus, though they remain important in the pollen assemblage until the mid-Holocene. After c. 3600 cal BP Calluna becomes more important but for the most part the understory around Loch Garten is composed of Juniperus and Gramineae (Poaceae). O‟Sullivan‟s (1976) analysis from Loch a‟Chnuic extends back to the Late-Devensian and is similar to others from the area; the main assemblages are of Pinus-Betula and Pinus-Betula with Alnus. Both O‟Sullivan (1974a, 1976) and Birks (1970) regard Betula and Alnus as occupying areas that are spatially distinct from Pinus, rather than gaps within the Pinus canopy, therefore competition between the three taxa is limited.

Birks (1975) reports Pinus expansion around Loch Einich at the expense of Betula with Corylus. Once Pinus was established, Betula persisted as part of a mainly

Pinus-heath assemblage. Binney‟s (1997) sites above Gleann Einich found no evidence of tree cover before the arrival of Pinus. The movement of Binney‟s pine front into a Calluna, Empetrum and Vaccinium heath reflects the altitude of at least 500m OD. After Pinus establishment, Binney (1997) showed that Calluna and Empetrum continued to be important. In the same area Pears‟ (1968) study is too taxonomically limited to show anything with certainty. Betula forms a large component of the assemblage but the basis of the count (taxa expressed as a

percentage of Arboreal Pollen) shows that Ericales are always the main component. In the eastern Cairngorms near Braemar, Pinus woodland replaced scrub and woodland vegetation “similar to the Betula-Juniperus woodlands found around the Morrone Birkwoods today” (Huntley 1994, page 328). Betula macrofossils (fruit and catkins) form part of the assemblage throughout the Holocene, placing Betula in the immediate vicinity of the site, but it is unclear if Betula grew, as now, altitudinally above Pinus, or the two grew together. Above 100cm Huntley (1994) reports Pinus percentages of 30-40% TLP with Betula percentage of around 10% TLP; this could indicate separate of Pinus and Betula woodland or a denser Pinus-Betula canopy.

At both Loch Davan and Braeroddach Loch, Pinus pollen increases at the expense of Betula and Coryloid (Edwards 1978); Edwards does not regard separation of Corylus from Myrica as valid (Edwards 1983). Betula remains an important part of the assemblage but the gradual decline of Betula shows that Pinus replaced Betula in the landscape. Gradually Quercus, Alnus and Ulmus became more widespread, largely replacing Pinus by c. 4500 cal BP.

Rannoch Moor is similar to other areas with expansion of Pinus into Betula- Corylus woodland (Walker and Lowe 1981, Bridge et al. 1990). As this substitution occurred, Corylus/Myrica was already in decline, but Betula remained largely

unchanged. There are oscillations between Betula or Alnus and Pinus during the Holocene, including almost complete disappearance of Pinus between c. 7300 cal BP and 5600 cal BP (Bridge et al. 1990) coinciding with the rise of Alnus. Its ability to colonise waterlogged soil means Alnus is more commonly regarded as a competitor to Pinus than to Betula. Calluna is present in all Bridge et al.‟s (1990) sites from the early Holocene onward but became more important in the pollen assemblage after Pinus declined at c. 4600 cal BP.