Pollen signals of ground flora in managed woodlands

Bunting, M. Jane; Grant, Michael J.; Waller, Martyn

doi:10.1016/j.revpalbo.2015.10.001

Cited by 9 publications

(6 citation statements)

References 43 publications

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“…Evidence for a strongly local component in the pollen signal comes from multiple investigations of modern pollen representation in wetland and grassland communities (e.g. Janssen, 1984;Hjelle, 1997;Bunting et al, 1998;Waller et al, 2005;Bunting et al, 2016) and from the fine scale heterogeneous mosaic nature of the vegetation deriving from the small size of individual plants and micro-scale variations in habitat (e.g. Bunting, 2003).…”

Section: Methodsmentioning

confidence: 99%

Disentangling the pollen signal from fen systems: Modern and Holocene studies from southern and eastern England

Waller

Carvalho

Grant

et al. 2017

Review of Palaeobotany and Palynology

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Thick deposits of peat derived from fen environments accumulated in the coastal lowland areas adjacent to the North Sea during the middle and late Holocene. These sediments are frequently used in pollen-based reconstructions of in situ and more distant vegetation. However, discriminating between wetland and dry land originating pollen signals, and between the potential fen communities present in the wetland, is complex. In this study, a suite of analytical approaches are used to explore the pollen signal of modern fen communities and compare them against Holocene pollen assemblages. At two sites in eastern England, Woodwalton Fen and Upton Broad, vegetation composition was recorded around a series of moss polster sampling points. The communities investigated included herbaceous fen communities under different cutting regimes, a grazed area, glades, and woodland with canopies dominated by Alnus glutinosa and Betula. Cluster analysis is used to provide an overview of, and compare the structure within, the datasets consisting of the vegetation, the vegetation converted to palynological equivalents, and the pollen data. It is demonstrated that any loss of taxonomic precision in pollen identifications does not pose particular problems when attempting to identify fen communities, including tall-herbaceous vegetation, in the pollen record. Indices of Association imply pollen presence can be interpreted as indicating the local presence for some taxa, though few of these are confined to a particular community. Herbaceous fen vegetation subject to different management regimes are, however, shown to produce distinctive pollen signatures. Middle and late Holocene pollen assemblages from eastern (Fenland) and southern (Romney Marsh) England, interpreted as derived from fen vegetation, are compared against the modern pollen dataset using ordination. Most of the fossil samples plot out within or adjacent to the groupings produced by the modern samples in the ordinations. While these investigations demonstrate that modern pollen work can help improve the interpretation of Holocene assemblages they also call attention to a number of limitations including the restricted range of communities from which modern samples are currently available and the potential for non-analogous modern vegetation. The paper concludes with ideas to aid the interpretation of pollen data collected from fen peats and suggestions for future work.

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Section: Methodsmentioning

confidence: 99%

Disentangling the pollen signal from fen systems: Modern and Holocene studies from southern and eastern England

Waller

Carvalho

Grant

et al. 2017

Review of Palaeobotany and Palynology

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“…With any of the interrupted sites, it is important to note that the temporary decreases in the abundance of arboreal pollen could feasibly be driven by a period of active coppice management rather than a genuine woodland interruption. However, the impact of coppicing on pollen records in woodland settings has been considered by Waller et al, (2012) and Bunting et al, (2016) and concluded that coppicing has little or no impact on pollen production. We can thus be confident that periods interpreted as woodland interruptions are likely to be just are clearance events, even those that are very short (e.g.…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

Questioning the reliability of “ancient” woodland indicators: Resilience to interruptions and persistence following deforestation

Webb

Goodenough

2018

Ecological Indicators

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Indicator species can provide invaluable insights into environmental conditions but robust empirical testing of their effectiveness is essential. Ancient woodland indicators (AWIs) are plant species considered indicative of sites that have been continuously wooded for a long period by virtue of poor dispersal ability and intolerance of nonwoodland habitats. Many countries now utilise AWI species lists to classify ancient woodlands. Here we use a metastudy approach to test resilience of AWIs to interruptions and persistence following deforestation-and thus the robustness of using AWI lists-using a novel approach. We compare current AWI assemblage with woodland history based on pollen evidence at nine sites across the UK with a robustly-dated and spatially-precise palynological profile. Sites were split into: (1) proven continuous woodland; (2) previously interrupted woodland; and (3) previously but not currently wooded. Vegetation history was >1000 years at most sites. Assessment of ancientness using AWIs agreed with palynologically-proven ancient woodland at two sites, including a species-poor woodland of previously-uncertain age. However, four interrupted woodland sites and three clear-felled sites supported extensive AWI floristic communities. This suggests AWIs are resilient to interruptions, possibly by remaining in the seed bank longer than expected, and persistent following deforestation. Persistence might be due to other species (e.g. heathland plants) acting as pseudo-canopy or because some AWIs are more tolerant of nonwoodland locations than previously thought. We conclude that use of floristic AWIs alone in defining ancient woodland should be reviewed, especially where status links to planning policy and conservation prioritisation. We suggest species on AWI lists be reviewed under expert and local guidance and a system of weighting species based on their strict or strong affinity solely with ancient woodland be developed. The use of multi-taxa indicators is recommended to allow stakeholders globally to make informed decisions about ancient woodland status.

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“…Tauber traps allow the time period covered by the pollen assemblages to be defined accurately, although the requirement for a long-term continuous series of annually collected data to avoid problems of interannual variations in pollen production (Hicks, 2003) means that this approach is not feasible within the lifespan of many research projects. Bunting et al (2015) show that there may be a significant degree of local heterogeneity between closely spaced Tauber traps, indicating that micro-scale variation between pollen assemblages is not peculiar to those contained within moss polsters. Lake surface sediment samples are another option (e.g.…”

Section: Accepted M Manuscriptmentioning

confidence: 88%

Replicability of data collected for empirical estimation of relative pollen productivity

Farrell

Bunting

Middleton

2016

Review of Palaeobotany and Palynology

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Pollen signals of ground flora in managed woodlands

Cited by 9 publications

References 43 publications

Disentangling the pollen signal from fen systems: Modern and Holocene studies from southern and eastern England

Disentangling the pollen signal from fen systems: Modern and Holocene studies from southern and eastern England

Questioning the reliability of “ancient” woodland indicators: Resilience to interruptions and persistence following deforestation

Replicability of data collected for empirical estimation of relative pollen productivity

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