Modern pollen rain predicts shifts in plant trait composition but not plant diversity along the Andes–Amazon elevational gradient

This is the final version. Available on open access from Wiley via the DOI in this record. Aims: Terrestrial ecosystems are changing in biodiversity, species composition and functional trait composition. To understand the underlying causes of these changes and predict the long-term resilience of the ecosystem to withstand future disturbances, we can evaluate changes in diversity and composition from fossil pollen records. Although diversity can be well estimated from pollen in temperate ecosystems, this is less clear for the hyperdiverse tropics. Moreover, it remains unknown whether functional composition of plant assemblages can be accurately predicted from pollen assemblage composition. Here, we evaluate how community-weighted mean (CWM) traits and diversity indices change along elevation. Location: Amazon–Andes elevation gradient in Peru. Methods: We used 82 modern pollen samples and 59 vegetation plots along the elevation gradient, and calculated CWM traits and diversity indices for each pollen sample and vegetation plot. We also quantified the degree to which taxa are over- or underrepresented by their pollen, by dividing the relative pollen abundance by the relative basal area abundance in the nearby vegetation survey plots (i.e. the R-rel values). Results: We found that CWM wood density increased, and CWM adult height and leaf area decreased with elevation. This change was well predicted by pollen assemblages, indicating that CWM trait–environment relationships based on pollen abundance data provide meaningful results. Diversity (richness, Shannon and Simpson) decreased with elevation for vegetation plots, but these trends could not be observed from pollen assemblages. Conclusions: Our results demonstrate that more research is needed to develop methods that lead to accurate diversity estimates from pollen data in these tropical ecosystems, but that CWM traits can be calculated from pollen data to assess spatial shifts in functional composition. This opens opportunities to calculate CWM traits from fossil pollen data sets in the tropics, with broad implications for improving our understanding and predictions of forest dynamics, functioning and resilience through time.Nederlandse Organisatie voor Wetenschappelijk Onderzoe

The Rano Kau 2 Pollen Diagram: Palaeoecology Revealed

OF THE THREE POTENTIAL SITES ON RAPA NUI for recovering a continuous palaeoecological record (Flenley et al.1991) Rano Kau has so far proved the best. Rano Raraku has a significant hiatus between 800 BP and c. 2000 BP (Mann et al.2008) and Rano Aroi has surface disturbance, as well as being above the altitude of likely early inhabitants. Rano Kau, however, offered a favorable microclimate for tropical crops (van Steenis 1935), a permanent water supply for early inhabitants, and a long continuous pollen record. Rano Kau core 1, collected in 1977 near the edge of the swamp, yielded a record spanning only just over a millennium. Rano Kau 2, collected in 1977 and near the centre of the caldera, however, has given a continuous record for the last 10 millenia. Initial problems with dating have now been resolved. Furthermore the position near the centre of Rano Kau is likely to give a more generalized record of the palaeoecology. We originally expected this to be an islandwide coverage, as predicted for the centre of large sites by Jacobsen and Bradshaw (1981). The caldera is, however, so deep (c. 200 metres), and the interior slopes so steep (c.30o), that the interior environment is almost windless, and rather isolated from the windy environment of the rest of the island. The result appears to be that each core taken reflects the vegetation on the nearest caldera slopes, with relatively less input than usual from the rest of the island or from long distance transported pollen

A carbonised wood sample from Rakata and its Radio-carbon Assay. I. Stratigraphic Observations

Provides a stratigraphical setting and discusses possible origins of the carbonised timber which has been dated by 14 C to AD 1710. The timber was found at c.4 m depth under a layer of ash with pumice and a topsoil

Late Quaternary environments and man in Holderness

14.00SIGLEAvailable from British Library Lending Division - LD:1863.1856(BAR-BS--134) / BLDSC - British Library Document Supply CentreGBUnited Kingdo