Long-term changes and drivers of biodiversity in Atlantic oakwoods

Mitchell, Fraser

doi:10.1016/j.foreco.2013.07.002

Cited by 10 publications

(7 citation statements)

References 39 publications

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“…In the British examples, long forest continuity and a close-to-nature disturbance regime were apparently not critical properties for the maintenance of important biological values. These findings fully support very similar observations made from four bryophyterich Quercus woodlands in Snowdonia, Wales, where pollen analysis showed significant forest disturbance during the last 300 years (Edwards 1986), and from Killarney National Park, Ireland (Mitchell 1988;Mitchell 1990;Mitchell 2013 (Lindbladh, Bradshaw et al 2000). All these sites are from local sites with high spatial resolution, but taken together they indicate consistent sequences of events.…”

Section: Discussionsupporting

confidence: 87%

“…Trees and other higher plants are probably the group of species that have the weakest recolonisation potential, and for these species, continuity of site occupation is more important. Palaeoecological studies of sites with high conservation value have increased understanding of forest dynamics and likely controls of diversity (Mitchell, 2013). Pollen studies with high spatial resolution demonstrate that simple temporal concepts like 'natural baselines' and the continuity of forest cover underestimate the complexity of the past.…”

Section: Discussionmentioning

confidence: 99%

“…These statements have rarely been rigorously tested within conservation biology, although forest cover for at least the last thousand years is included in the CBD primary forest definition (Table 1) and our understanding of the relationship between ancient and primary European woodlands has developed through time (Goldberg, Kirby et al 2007). It is timely to test hypotheses about the conservation value of long forest continuity against more of the data that have appeared from forest hollows since 1993 (Willis and Birks 2006;Birks 2012;Mitchell 2013) and here we present three forest hollow sites from the British Isles and Sweden. All the sites are protected nature reserves today and part of their natural values have been presumed to be linked with long forest continuity.…”

Section: Introductionmentioning

confidence: 99%

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Forest continuity and conservation value in Western Europe

et al. 2014

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Abstract:Long forest continuity has often been linked with high conservation value in western European Quercus and Fagus woodlands, but this assumption of long continuity has rarely been tested. Birks (1993) discussed the antiquity of bryophyte-rich Quercus woodland in western United Kingdom presenting evidence that the modern plant communities developed during the late Holocene influenced by human activities. We use pollen data from forest hollows to show that the modern communities within ancient woodlands are all significantly influenced by recent human disturbance. A short period of deforestation in Johnny's Wood, Cumbria, UK dates from the late nineteenth century and is not of Viking age as previously thought. The brief opening of the forest is associated with the local loss of Tilia cordata and Taxus baccata, but a rich bryophyte community exists today. Rich lichen floras of high conservation interest growing on Fagus sylvatica in southwestern Sweden occur despite a recent history of human disturbance and local immigration of Fagus as recently as the ninth century AD. Wistman's Wood, Cornwall, UK had a diverse tree flora until the eleventh century AD and then experienced heavy browsing and grazing until AD 1850, after which time the present Quercus woodland developed with its associated flora of high conservation value. Most western European forests today have long and diverse histories of anthropogenic disturbance and current conservation values incorporate both natural and cultural features. Pollen studies with high spatial resolution demonstrate that simple temporal concepts like 'natural baselines' and the continuity of forest cover underestimate the complexity of the past. Long forest continuity may be of importance for the local survival of higher plants, but for the insects, fungi, lichens and bryophytes that are so valued in contemporary European temperate and boreal forests, habitat diversity maintained by dynamic processes would appear to be of greater significance. spatial resolution demonstrate that simple temporal concepts like 'natural baselines' and the continuity of forest cover underestimate the complexity of the past. Long forest continuity may be of importance for the local survival of higher plants, but for the insects, fungi, lichens and bryophytes that are so valued in contemporary European temperate and boreal forests, habitat diversity maintained by dynamic processes would appear to be of greater significance.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Forest continuity and conservation value in Western Europe

et al. 2014

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“…Trends in biodiversity have also been investigated at local scales (sensu McGill et al, 2015) using pollen data (e.g. Mitchell, 2013). However, there are too few data from this scale to permit recognition of any consistent general trends.…”

Section: Figurementioning

confidence: 99%

Biodiversity trends within the Holocene

2016

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There is a rapidly emerging interest in detecting and understanding biodiversity trends during the ‘Anthropocene’ in response to human stressors and climate change. Surprisingly few studies have, however, considered trends in biodiversity during the preceding Holocene. Here, we present general trends in terrestrial alpha- and beta-diversity and biomass for the four main ecological phases (protocratic, mesocratic, Homo sapiens, oligocratic) of the Holocene in north-west Europe based on palynological data at the meta-community scale. Alpha- and beta-diversity decreased in the protocratic, showed little change in the mesocratic, decreased in the oligocratic, and increased markedly in the Homo sapiens phase. Biomass was maximal in the mesocratic. Biodiversity changes in the last 200 years (‘Anthropocene’), as detected from palynological data, are small compared with the changes over the Holocene. There are minor decreases in α-diversity, spatial β-diversity and biomass and a slight increase in temporal β-diversity at sites on fertile soils. This analysis is designed to encourage ecologists and biogeographers interested in the ‘Anthropocene’ to extend the time-scale of their analyses and to consider whether ‘Anthropocene’ biodiversity trends are a simple continuation of trends in the late Holocene or whether recent ‘Anthropocene’ trends deviate from the long-term Holocene trends. Hopefully, it will also stimulate palaeoecologists to consider Holocene biodiversity trends in different geographical areas and different organism groups and ecological systems.

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“…Small hollows and mor humus deposits have been identified as important potential sources of local pollen, plant macrofossil and insect assemblages, providing a clearer picture of drivers of Holocene woodland composition change including climate, topography, human impact (fire, grazing) and local edaphic factors (Bradshaw, 2007; Mitchell, 2013; Overballe-Petersen and Bradshaw, 2011; Reilly, 2008). Establishing a robust chronology for such deposits is critical to understanding the timing and duration of changes noted within pollen, plant macrofossil and insect assemblages.…”

Section: Introductionmentioning

confidence: 99%

Establishing chronologies for woodland small hollow and mor humus deposits using tephrochronology and radiocarbon dating

Reilly

Mitchell

2014

The Holocene

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Chronological precision is a pre-requisite for all palaeoecological analyses, especially in more recent Holocene deposits such as small hollow peat and mor humus in woodlands. Here, tephrochronology was employed to improve the chronological control of such deposits to aid subsequent sub-fossil insect analyses from three sites in western and southwestern Ireland. Six tephra layers were detected from the three small hollows but only one from the mor humus sites. Four of the layers were matched to known tephra horizons regularly recorded in Ireland while two new tephras of possible Azores and Grímsvötn origin were recorded. The latter tephra may be the first definitive record of Laki 1783-4 from Ireland and is potentially an important new chronological marker for Irish palaeoecological investigations of late Holocene deposits. Results suggest that tephrochronology is a successful additional chronological tool for small hollow palaeoecological studies but is less helpful in mor humus deposits.

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Long-term changes and drivers of biodiversity in Atlantic oakwoods

Cited by 10 publications

References 39 publications

Forest continuity and conservation value in Western Europe

Forest continuity and conservation value in Western Europe

Biodiversity trends within the Holocene

Establishing chronologies for woodland small hollow and mor humus deposits using tephrochronology and radiocarbon dating

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