Comment on : Pollen-based reconstruction of Holocene land-cover in mountain regions: Evaluation of the landscape reconstruction algorithm in the Vicdessos valley, northern Pyrenees, France

Currently interaction between climate and land-cover change in the past across the globe, and whether drivers are anthropogenic or natural are among the biggest debates. The impacts of climate and land-cover change are having significant consequences on biodiversity and ecosystems. Wide ranging palaeoenvironmental methods have contributed to this debate by providing long-term records of both climate and land-cover change. This provide the context for evaluating the effect of land-cover change on climate.&#160; Inferred past land-cover and climate change from palaeoecological proxies therefore need to be quantified to provide reliable estimates of change; there are several methods of quantifying land-cover change in the past of which the Landscape Reconstruction Algorithm (LRA) &#160;can estimate past land-cover change quantitatively at both regional and local spatial scales using fossil pollen records. The LRA includes two models (REVEALS and LOVE) and has already been tested and validated in Europe, North America, and China.In this study, we apply the LRA on Holocene pollen records in Cameroon to estimate past land-cover change. This is the first pollen-based, quantitative land-cover reconstruction using LRA in Africa.&#160; It will provide a comparison with land-cover change described from raw pollen data and useful information for climate modelling. The first phase involved the estimation of relative pollen productivity (RPP) for 13 taxa using the pollen-vegetation relationship described by the ERV model. The second phase involves the application of LRA using the RPPs from the 13 taxa.&#160;&#160;Acknowledgements: We thank the French ANR (National Research Agency; projects C3A ANR-09-PEXT-001 and VULPES ANR-15-MASC-0003) and the Belgian project BR/132/A1/AFRIFORD for financial support, IRD (France) and the Ministry of Research and National Herbarium of Cameroon for research facilities and authorizations, and A. Vincens, J.-P. Cazet, G. Buchet, L. F&#233;vrier, and K. Lemonnier (CNRS) for laboratory and field assistance. The study is a contribution to PAGES LandCover6k (www.pastglobalchanges.org/ini/wg/landcover6k/intro).

Download Full-text

Spatially Continuous Land-Cover Reconstructions Through the Holocene in Southern Sweden

Ecosystems ◽

10.1007/s10021-020-00594-5 ◽

2021 ◽

Author(s):

Robert O’Dwyer ◽

Laurent Marquer ◽

Anna-Kari Trondman ◽

Anna Maria Jönsson

Keyword(s):

Land Cover ◽

Regional Scale ◽

Coniferous Forest ◽

Reconstruction Algorithm ◽

Fossil Pollen ◽

Conifer Forest ◽

Southern Sweden ◽

The Holocene ◽

Simple Kriging ◽

Pollen Records

AbstractClimate change and human activities influence the development of ecosystems, with human demand of ecosystem services altering both land use and land cover. Fossil pollen records provide time series of vegetation characteristics, and the aim of this study was to create spatially continuous reconstructions of land cover through the Holocene in southern Sweden. The Landscape Reconstruction Algorithm (LRA) was applied to obtain quantitative reconstructions of pollen-based vegetation cover at local scales, accounting for pollen production, dispersal, and deposition mechanisms. Pollen-based local vegetation estimates were produced from 41 fossil pollen records available for the region. A comparison of 17 interpolation methods was made and evaluated by comparing with current land cover. Simple kriging with cokriging using elevation was selected to interpolate the local characteristics of past land cover, to generate more detailed reconstructions of trends and degree of variability in time and space than previous studies based on pollen data representing the regional scale. Since the Mesolithic, two main processes have acted to reshape the land cover of southern Sweden, originally mostly covered by broad-leaved forests. The natural distribution limit of coniferous forest has moved southward during periods with colder climate and retracted northward during warmer periods, and human expansion in the area and agrotechnological developments has led to a gradually more open landscape, reaching maximum openness at the beginning of the 20th century. The recent intensification of agriculture has led to abandonment of less fertile agricultural fields and afforestation with conifer forest.

Download Full-text