Archaeobotanical evidence for climate as a driver of ecological community change across the anthropocene boundary.

The biodiversity response to climate change is a major focus in conservation research and policy. Predictive models that are used to project the impact of climate change scenarios - such as bioclimatic envelope models - are widely applied and have come under severe scrutiny. Criticisms of such models have focussed on at least two problems. First, there is an assumption that climate is the primary driver of observed species distributions ('climatic equilibrium'), when other biogeographical controls are often reliably established. Second, a species' sensitivity to macroclimate may become less relevant when impacts are down-scaled to a local level, incorporating a modifying effect of species interactions structuring communities. This article examines the role of different drivers (climate, pollution and landscape habitat structure) in explaining spatial community variation for a widely applied bioindicator group: lichen epiphytes. To provide an analysis free of 'legacy effects' (e.g. formerly higher pollution loads), the study focused on hazel stems as a relatively short-lived and recently colonized substratum. For communities during the present day, climate is shown to interact with stem size/age as the most likely explanation of community composition, thus coupling a macroclimatic and community-scale effect. The position of present-day communities was projected into ordination space for eight sites in England and compared to the position of historical epiphyte communities from the same sites, reconstructed using preserved hazel wattles dating mainly to the 16th Century. This comparison of community structure for the late- to post-Mediaeval period, with the post-Industrial period, demonstrated a consistent shift among independent sites towards warmer and drier conditions, concurrent with the end of the Little Ice Age. Long-term temporal sensitivity of epiphyte communities to climate variation thus complements spatial community patterns. If more widely applied, preserved lichen epiphytes have potential to generate new baseline conditions of environment and biodiversity for preindustrial lowland Europe.

Archaeobotanical evidence for a massive loss of epiphyte species richness during industrialization in southern England.

This paper describes a novel archaeological resource--preserved epiphytes on the timber structure of vernacular buildings--used, to our knowledge, for the first time to quantify a loss of biodiversity between pre-industrial and post-industrial landscapes. By matching the confirmed occurrence of epiphyte species for the pre-industrial period, with a statistical likelihood for their absence in the present-day landscape (post-1960), we robustly identified species that have been extirpated across three contrasting regions in southern England. First, the scale of biodiversity loss observed--up to 80 per cent of epiphytes--severely challenges biodiversity targets and environmental baselines that have been developed using reference points in the post-industrial period. Second, we examined sensitivity in the present-day distribution of extirpated species, explained by three environmental drivers: (i) pollution regime, (ii) extent of ancient woodland, and (iii) climatic setting. Results point to an interacting effect between the pollution regime (sulphur dioxide) and changed woodland structure, leading to distinctive regional signatures in biodiversity loss.

DNA barcoding of lichenized fungi demonstrates high identification success in a floristic context.

• Efforts are currently underway to establish a standard DNA barcode region for fungi; we tested the utility of the internal transcribed spacer (ITS) of nuclear ribosomal DNA for DNA barcoding in lichen-forming fungi by sampling diverse species across eight orders. • Amplification of the ITS region (ITS1-5.8S-ITS2) was conducted for 351 samples, encompassing 107, 55 and 28 species, genera and families, respectively, of lichenized fungi. We assessed the ability of the entire ITS vs the ITS2 alone to discriminate between species in a taxonomic dataset (members of the genus Usnea) and a floristic dataset. • In the floristic dataset, 96.3% of sequenced samples could be assigned to the correct species using ITS or ITS2; a barcode gap for ITS is present in 92.1% of species. Although fewer species have a barcode gap in the taxonomic dataset (73.3% with ITS and 68.8% with ITS2), up to 94.1% of samples were assigned to the correct species using BLAST. • While discrimination between the most closely related species will remain challenging, our results demonstrate the potential to identify a high percentage of specimens to the correct species, and the remainder to the correct genus, when using DNA barcoding in a floristic context.