Pollen analytical and landscape reconstruction study at Lake Storsjön, southern Sweden, over the last 2000 years

Pollenanalys och landskapsrekonstruktionsmodellering (modellen REVEALS) användes för att undersöka landskapsutvecklingen i Botorpsströmmens dräneringsområde i södra Sverige över de senaste 2000 åren. Studien ingår i två större projekt, The archaeology and ecology of collapse: social and agricultural change following the Black Death och Managing Multiple Stressors in the Baltic Sea. Resultaten från studien kopplades till hur Östersjön har påverkats av markanvändningsförändringar under de senaste 2000 åren. Tre av sex insamlade borrkärnor (SSK, SS1a och SS1b) från Storsjön, Småland analyserades och provtogs för pollenanalys, LOI, 14C-datering och 210Pb-datering. Dateringarna är ännu inte färdiga och därför användes pollendiagram från andra studier i södra Sverige tillsammans med ett lågupplöst pollendiagram sammansatt från alla de erhållna borrkärnorna från Storsjön för att upprätta en relativ kronologi av de studerade sedimenten. Resultaten från pollenanalysen sammanställdes i ett högupplöst pollendiagram och i ett vegetations-fördelningsdiagram. Diagrammen indelades sedan i fem perioder (A-E) där period C delades in i fyra delperioder (C1-C4). Etableringen av Picea, det första pollenkornet av Secale t. och det första uppträdandet av en kontinuitet i sädesslagspollenkurvan antyder att period A representerar tidsintervallet mellan 250-500 e.Kr. Period B karakteriseras av en nedgång i odling och en succession av träd som förmodligen representerar återbeskogningen under 500-talet. Delperiod C1 utmärks av en expansion av jordbruk vilket tolkas som den medeltida expansionen 800-1300 e.Kr. En återbeskogning och en nedgång i odling kännetecknar delperiod C2, vilken bör representera den medeltida nedgången under 1300-talet. Delperioderna C3 och C4 karakteriseras av en förnyad expansion av jordbruk och representerar troligtvis 1500-talet. Höga värden av sädesslag och introduktionen av bovete i period D antyder att perioden representerar 1600-talet till 1800-talet. En återbeskogning av Picea och Pinus, nedgång i artrikedom och höga värden av sädesslag kännetecknar period E vilket tyder på att perioden representerar sent 1800-tal till 1900-tal. Ökad markanvändning under de senaste 2000 åren har kopplats till perioder av syrefattiga bottenförhållanden i Östersjön och perioder av minskad markanvändning har kopplats till perioder av mer syrerika bottenförhållanden i Östersjön. Denna studie ger en ökad förståelse för landskapsutvecklingen i södra Sverige inom ett område som tidigare inte har varit föremål för studier och vidare indikerar studien att markanvändningen under de senaste 2000 åren i södra Sverige kännetecknades av perioder av ökad markanvändning och perioder av minskad markanvändning.This thesis reports the results from a pollen analytical and quantitative landscape reconstruction (REVEALS model) study in the drainage area of the Botorpsströmmen River in southern Sweden as a part of the project The archaeology and ecology of collapse: social and agricultural change following the Black Death and the project Managing Multiple Stressors in the Baltic Sea. The focus of this study was on the vegetation and land-use development in the area during the last 2000 years and on how the land-use changes affected the Baltic Sea. Six sediment cores were retrieved from Lake Storsjön, Småland, and three of those cores (SSK, SS1a and SS1b) were used for further analyses. The sediment cores were sampled for pollen analysis, LOI, 14C-dating and 210Pb-dating; the dating results are still pending. Pollen diagrams from other studies in southern Sweden along with a low resolution pollen diagram based on all the six retrieved cores have been used for tentative dating. A high resolution pollen diagram and a vegetation cover diagram were constructed using data from cores SSK and SS1a. The diagrams were divided into five landscape periods (A-E), where period C further was divided into four sub-periods (C1-C4). Period A probably represents the time interval between approximately AD 250 and AD 500 and shows the establishment of Picea, the first finding of Secale t. and the first appearance of a continuous cereal pollen curve. Period B is characterised by reforestation and farm abandonment and most likely represents the reforestation event during the 6th century. Sub-period C1 shows an expansion of agriculture and is interpreted as the Medieval expansion around AD 800-1300. This is followed by reforestation and farm abandonment in sub-period C2 that suggest that this represents the Medieval decline during the 14th century. Sub-periods C3 and C4 are characterised by a re-expansion of agriculture and probably represent the 16th century. The introduction of buckwheat and a peak in cereal pollen in period D suggest that this period represents the vegetation and land-use during the 17th to 19th centuries. Period E is characterised by a reforestation of Picea and Pinus, decline in species diversity and high values of cereals that probably represent the late 19th to 20th centuries. Based on literature, periods of hypoxia in the Baltic Sea during the last 2000 years have been correlated with intense agricultural periods and periods of more oxic conditions have been correlated with periods of agricultural decline. This study gives an insight into the vegetation and land-use changes in an area of southern Sweden that has not been subject to previous studies and indicates that the agriculture during the last 2000 years was characterised by periods of intensified land-use and periods of reduced land-use

Long-term ecological legacies in western Amazonia

M.B.B would like to acknowledge funding from the National Science Foundation (grant nos. EAR1338694 and BCS0926973), the Belmont Forum, and the National Aeronautics and Space Administration (grant no. NNX14AD31G). C.N.H.M would like to acknowledge funding from the European Research Council (ERC 2019 StG 853394). C.N.H.M and M.F.R would like to acknowledge funding from the Netherlands Organisation for Scientific Research (ALWOP.322). S.N.H, M.P, and Jo.V performed this research as a part of the BSc research program of the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam.1. Modifications of Amazonian forests by pre‐Columbian peoples are thought to have left ecological legacies that have persisted to the modern day. Most Amazonian palaeoecological records do not, however, provide the required temporal resolution to document the nuanced changes of pre‐Columbian disturbance or post‐disturbance succession and recovery, making it difficult to detect any direct, or indirect, ecological legacies on tree species. 2. Here, we investigate the fossil pollen, phytolith and charcoal history of Lake Kumpaka, Ecuador, during the last 2,415 years in c. 3–50 year time intervals to assess ecological legacies resulting from pre‐Columbian forest modification, disturbance, cultivation and fire usage. 3. Two cycles of pre‐Columbian cultivation (one including slash‐and‐burn cultivation, the other including slash‐and‐mulch cultivation) were documented in the record around 2150–1430 cal. year BP and 1250–680 cal. year BP, with following post‐disturbance succession dynamics. Modern disturbance was documented after c. 10 cal. year BP. The modern disturbance produced a plant composition unlike those of the two past disturbances, as fire frequencies reached their peak in the 2,415‐year record. The disturbance periods varied in intensity and duration, while the overturn of taxa following a disturbance lasted for hundreds of years. The recovery periods following pre‐Columbian disturbance shared some similar patterns of early succession, but the longer‐term recovery patterns differed. 4. Synthesis. The trajectories of change after a cessation of cultivation can be anticipated to differ depending on the intensity, scale, duration and manner of the past disturbance. In the Kumpaka record, no evidence of persistent enrichment or depletion of intentionally altered taxa (i.e. direct legacy effects) was found but indirect legacy effects, however, were documented and have persisted to the modern day. These findings highlight the strengths of using empirical data to reconstruct past change rather than relying solely on modern plant populations to infer past human management and ecological legacies, and challenge some of the current hypotheses involving the persistence of pre‐Columbian legacies on modern plant populations.Publisher PDFPeer reviewe

European pollen-based REVEALS land-cover reconstructions for the Holocene: methodology, mapping and potentials

Quantitative reconstructions of past land cover are necessary to determine the processes involved in climate–human–land-cover interactions. We present the first temporally continuous and most spatially extensive pollen-based land-cover reconstruction for Europe over the Holocene (last 11 700 cal yr BP). We describe how vegetation cover has been quantified from pollen records at a 1∘ × 1∘ spatial scale using the “Regional Estimates of VEgetation Abundance from Large Sites” (REVEALS) model. REVEALS calculates estimates of past regional vegetation cover in proportions or percentages. REVEALS has been applied to 1128 pollen records across Europe and part of the eastern Mediterranean–Black Sea–Caspian corridor (30–75∘ N, 25∘ W–50∘ E) to reconstruct the percentage cover of 31 plant taxa assigned to 12 plant functional types (PFTs) and 3 land-cover types (LCTs). A new synthesis of relative pollen productivities (RPPs) for European plant taxa was performed for this reconstruction. It includes multiple RPP values (≥2 values) for 39 taxa and single values for 15 taxa (total of 54 taxa). To illustrate this, we present distribution maps for five taxa (Calluna vulgaris, Cerealia type (t)., Picea abies, deciduous Quercus t. and evergreen Quercus t.) and three land-cover types (open land, OL; evergreen trees, ETs; and summer-green trees, STs) for eight selected time windows. The reliability of the REVEALS reconstructions and issues related to the interpretation of the results in terms of landscape openness and human-induced vegetation change are discussed. This is followed by a review of the current use of this reconstruction and its future potential utility and development. REVEALS data quality are primarily determined by pollen count data (pollen count and sample, pollen identification, and chronology) and site type and number (lake or bog, large or small, one site vs. multiple sites) used for REVEALS analysis (for each grid cell). A large number of sites with high-quality pollen count data will produce more reliable land-cover estimates with lower standard errors compared to a low number of sites with lower-quality pollen count data. The REVEALS data presented here can be downloaded from https://doi.org/10.1594/PANGAEA.937075 (Fyfe et al., 2022)

Risks to carbon storage from land-use change revealed by peat thickness maps of Peru

This work was funded by NERC (grant ref. NE/R000751/1) to I.T.L., A.H., K.H.R., E.T.A.M., C.M.A., T.R.B., G.D. and E.C.D.G.; Leverhulme Trust (grant ref. RPG-2018-306) to K.H.R., L.E.S.C. and C.E.W.; Gordon and Betty Moore Foundation (grant no. 5439, MonANPeru network) to T.R.B., E.N.H.C. and G.F.; Wildlife Conservation Society to E.N.H.C.; Concytec/British Council/Embajada Británica Lima/Newton Fund (grant ref. 220–2018) to E.N.H.C. and J.D.; Concytec/NERC/Embajada Británica Lima/Newton Fund (grant ref. 001–2019) to E.N.H.C. and N.D.; the governments of the United States (grant no. MTO-069018) and Norway (grant agreement no. QZA-12/0882) to K.H.; and NERC Knowledge Exchange Fellowship (grant ref no. NE/V018760/1) to E.N.H.C.Tropical peatlands are among the most carbon-dense ecosystems but land-use change has led to the loss of large peatland areas, associated with substantial greenhouse gas emissions. To design effective conservation and restoration policies, maps of the location and carbon storage of tropical peatlands are vital. This is especially so in countries such as Peru where the distribution of its large, hydrologically intact peatlands is poorly known. Here field and remote sensing data support the model development of peatland extent and thickness for lowland Peruvian Amazonia. We estimate a peatland area of 62,714 km2 (5th and 95th confidence interval percentiles of 58,325 and 67,102 km2, respectively) and carbon stock of 5.4 (2.6–10.6) PgC, a value approaching the entire above-ground carbon stock of Peru but contained within just 5% of its land area. Combining the map of peatland extent with national land-cover data we reveal small but growing areas of deforestation and associated CO2 emissions from peat decomposition due to conversion to mining, urban areas and agriculture. The emissions from peatland areas classified as forest in 2000 represent 1–4% of Peruvian CO2 forest emissions between 2000 and 2016. We suggest that bespoke monitoring, protection and sustainable management of tropical peatlands are required to avoid further degradation and CO2 emissions.PostprintPeer reviewe

Warming, drought, and disturbances lead to shifts in functional composition: a millennial‐scale analysis for Amazonian and Andean sites

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of acquisitive, disturbance-adapted taxa with small seeds for quick colonization of disturbed sites, large leaves for light capture, and soft wood to attain fast height growth. Fire had weak effects on lowland forests but led to more stress-adapted taxa that are tall with fast life cycles and small seeds that can quickly colonize burned sites. Site-specific analyses were largely in line with cross-site analyses, except for varying site-level effects of El Niño frequency and fire activity, possibly because regional patterns in El Niño are not a good predictor of local changes, and charcoal abundances do not reflect fire intensity or severity. With future global changes, tropical Amazonian and Andean forests may transition toward shorter, drought- and disturbance-adapted forests in the lowlands but taller forests in the highlands

The Eurasian Modern Pollen Database (EMPD), version 2

The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019)Swiss National Science Foundation | Ref. 200021_16959

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change