61. A pollen record from Lake Öagöl (south-Swedish Uplands): 1500 years of land-use history

Lake Öagöl (57° 12′ 34″; 14° 48′ 03″) is situated in the central part of the province of Småland, southern Sweden, a region characterised by mixed woodlands and small-scale agriculture. The investigated lake has a circular to squarish shape and covers 1.8 ha. A minor road runs through the catchment area (which is 22 ha) on the western side of the lake (approximately 100 m from the lake shore). The nearest village is situated about 2 km away. Historical maps from the nineteenth century show that cultivated fields and hay meadows were situated close to the village. The maps also show that the immediate area around the lake was part of the land, which was mainly used for grazing and wood resources, and that the nearest hay meadow was approximately 500 m away. Today, the land-cover around the lake is mixed woodland, dominated by spruce plantations. On the western side of the lake catchment is a local nature reserve (Kråketorpsskogen, 200 ha), which is protected from modern forestry.publishedVersio

Inferring Long-term Landuse Development Through On-site Botanical Analyses at Øvre Øksnevad, Southwestern Norway

This study analysed pollen and plant macrofossils from mainly Bronze Age and Iron Age funerary, agricultural and settlement remains, to infer local plant exploitation and long-term land-use development at Øvre Øksnevad in southwestern Norway. The results showed that deciduous woodland covered the site prior to c. 2100 BC. After this, until c. 500 BC, the vegetation became dominated by grasses/herbs, while several phases of land clearance and cultivation were identified. The main human activity on the site was c. 600-300 BC, when a settlement was established and most of the 103 cairns registered at the site were constructed. Grazing on heathland was the main land-use from 300 BC, until another short-lived settlement was established c. AD 1-200, while regular burning of the heathland occurred from c. AD 1300. The relatively short-lived settlement at Øvre Øksnevad suggests it was marginal and only used during times of high population pressure, a conclusion which is supported by the botanical evidence. This study demonstrates how comprehensive sampling for botanical remains can contribute to the understanding of complex archaeological sites, including local land-use development and human-plant interactions.publishedVersio

Naturvetenskapliga undersökningar på Sømme I, ID 150777, Lokal 10 : gnr. 15, bnr. 5, Sola kommun, Rogaland

Oppdragsgiver: Statens vegvesenI samband med en arkeologisk utgrävning vid Sømmevågen (Sømme I, ID 150777, Lokal 10) analyserades pollen- och makrofossilprover. Proverna togs ut från förhistoriska åkrar och lämningar från stenålder. De flesta kulturlager och anläggningar från stenålder innehöll hasselnötsskal (Corylus avellana). I en anläggning (nr. 2) förekom ett frö av vete (cf. Triticum) som daterades till romersk järnålder. Åkerlagren innehöll ett mindre antal frön av gräs och ogräs. Polleninnehållet i åkerlagren visade på ett öppet landskap med åker och betesmark

Naturvitenskapelige undersøkelser på Grødaland : Hobberstad, gnr. 40, bnr. 7, Hå k. Rogaland

Oppdragsgiver: Rogaland fylkeskommuneTo makroprøver og fem pollenprøver ble innsamlet fra en profil på Hobberstad, Hå k. i forbindelse med RFKs registrering for gang og sykkelvei langs Fv. 44. Pollenalanysen viser et i hovedsak åpent landskap og det ble funnet pollen fra korn og åkerugress. I makrofossilprøvene ble det funnet bygg, havre og vanlige åkerugress som bekrefter at det er en dyrkningsprofil med fossile åkerlag

Floristic diversity in the transition from traditional to modern land-use in southern Sweden A.D. 1800-2008

International audienceWe aim to provide a long-term ecological analysis of land-use and floristic diversity in the transition from traditional to modern land-use management in the time A.D. 1800-2008 in southern Sweden. We use the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model to quantify land-cover changes on a regional scale at 20-year intervals, based on the fossil pollen record. Floristic richness and evenness are estimated using palynological richness and the Shannon index applied to the REVEALS output, respectively. We identified a transition period of 60 years between 1880 and 1940 when the total tree cover increased and the tree composition changed from deciduous to coniferous dominance. Within the shrinking area of open land, arable land taxa expanded, while the number and coverage of herbs in the remaining grasslands decreased. The succession from open grasslands to more tree-covered habitats initially favoured palynological richness, which reached its highest values during the first 40 years of the transition period. The highest REVEALS-based evenness was recorded in the time of traditional land-use and at the beginning of the transition period, reflecting higher habitat diversity at these time intervals. Our results support a more dynamic ecosystem management that changes between traditional land-use and phases of succession (\40 years) to promote floristic diversity. We have developed and applied a palaeoecological methodology that contributes realistic estimates to be used in ecosystem management

The impact of land-use change on floristic diversity at regional scale in southern Sweden 600 BC-AD 2008

International audienceThis study explores the relationship between landuse and floristic diversity between 600BC and AD2008 in the uplands of southern Sweden. We use fossil pollen assemblages and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model to quantitatively reconstruct land cover at a regional scale. Floristic richness and evenness are estimated using palynological richness and REVEALS-based evenness, respectively. We focus on the period AD350 to 750 to investigate the impact of an inferred, short-lived (<200 yr) period of land-use expansion and subsequent land abandonment on vegetation composition and floristic diversity. The observed vegetation response is compared to that recorded during the transition from traditional to modern land-use management at the end of the 19th century. Our results suggest that agricultural land use was most widespread between AD350 and 1850, which correlates broadly with high values of palynological richness. REVEALS-based evenness was highest between AD500 and 1600 which indicates a more equal cover among taxa during this time interval. Palynological richness increased during the inferred land-use expansion after AD350 and decreased during the subsequent regression AD550-750, while REVEALS-based evenness increased throughout this period. The values of palynological richness during the last few decades are within the range observed during the last 1650 yr. However, REVEALS-based evenness shows much lower values during the last century compared to the previous ca. 2600 yr, which indicates that the composition of presentday vegetation is unusual in a millennial perspective. Our results show that regional scale changes in land use have had clear impacts on floristic diversity in southern Sweden, with a vegetation response time of less than 20 to 50 yr. We show the importance of traditional land use to attain high biodiversity and suggest that ecosystem management should include a regional landscape perspective

Two hundred years of land-use change in the South Swedish Uplands : comparison of historical map-based estimates with a pollen-based reconstruction using the landscape reconstruction algorithm

International audienceLong-term records of environmental history at decadal to millennial timescales enable an assessment of ecosystem variability and responses to past anthropogenic disturbances and are fundamental for the development of environmental management strategies. This study examines the local variability of land-use history in the South Swedish Uplands over the last 200 years based on pollen records from three lake-sediment successions. Temporal changes in the proportional cover of 14 plant taxa were quantified as percentages using the landscape reconstruction algorithm (LRA). The LRA-based estimates of the extent of four land-use categories (cropland, meadows/grassland, wetland, outland/woodland) were compared to corresponding estimates based on historical maps and aerial photographs from AD 1769–1823, 1837–1895, 1946 and 2005. Although the LRA approach tends to overestimate grassland cover by 10–30 % for the two earliest time periods, the reconstructed vegetation composition is generally in good agreement with estimates based on the historical records. Subsequently, the LRA approach was used to reconstruct the 200-year history of local land-use dynamics at 20-year intervals around two small lakes. The qualitative assessment of difference approach , which requires fewer assumptions and parameters than LRA for objective evaluation of between-site differences in plant abundances, provides consistent results in general. Significant differences exist in the land-use history between the sites. Local catchment characteristics, such as soil conditions and wetland cover, appear important for the development of human impact on the landscape. Quantifi-cations of past vegetation dynamics provide information on the amplitude, frequency and duration of the land-use changes and their effects on terrestrial and aquatic ecosystems , and should be taken into account when nature conservation strategies are developed

The impact of past land-use change on floristic diversity in southern Sweden : a quantitative approach based on high-resolution pollen data

This thesis explores the relationship between land-use and floristic diversity over the last three millennia in the uplands of southern Sweden. A quantitative approach based on high-resolution pollen data was applied, using the Landscape Reconstruction Algorithm (LRA), historical maps/aerial photographs, palynological richness and new ways to estimate past evenness at regional and local spatial scales, which enable estimates of the rate and degree of change in land-use and floristic diversity. The results show that agricultural land-use was most widespread AD 350-1850 at a regional scale, and a period of land-use expansion followed by regression AD 350-750 was identified. The land-use patterns were similar around the local study sites, with agricultural expansion during the 13th century, partly abandoned landscape around AD 1400, re-establishment during the 15-16th century and a transition from traditional to modern land-use during the 20th century. Palynological richness responds within 20 to 80 years during agricultural expansion and regression both at regional and local scales, which provides quantitative estimates of the ecosystem resilience to land-use changes. During succession from open land to more tree covered habitats, floristic richness may increase temporarily during c. 40 years. The REVEALS and LOVE-based evenness introduced in this thesis reflects changes in landscape composition and the extent of available habitats. The more widespread agriculture from the 13th to 19th century was of substantial importance for achieving the high floristic diversity that characterizes the traditional landscape, which can allow species favoured by traditional management, succession and woodlands to coexist. The modern landscape is unusual in a centennial to millennial perspective with more habitats related to coniferous woods and fewer habitats related to deciduous trees and open land taxa, which may not be sustainable to preserve floristic diversity in the future. This thesis provides some examples of long-term (decadal to millennial scale) impacts of land-use changes on floristic diversity at regional and local scales, and the adopted approach is potentially a useful tool for conservation strategies when planning management within specific areas

Holocene relative sea-level changes in the Tasiusaq area, southern Greenland, with focus on the Ta4 basin

Endast ett fåtal observationer har tidigare gjorts från inre delen av Bredefjorden i södra Grönland. I denna studie presenteras en ny strandförskjutningskurva från området kring Tasiusaq baserad i huvudsak på sedimentanalyser från en marin bassäng. Havsnivåförändringar registreras i sediment genom förändrad grundämneskoncentration, fysiska egenskaper och makrofossilinnehåll. Detta sker när en bassäng blir frånkopplad från havet under en regression alternativt sammankopplad med havet under en transgression. Övergångar från marina till lakustrina förhållanden (och tvärt om) i sediment har identifierats med litologi, glödförlust, XRF och makrofossilanalys, och utvalda nivåer har daterats med AMS. Dessutom har GPS använts för att mäta bassänghöjder med utgångspunkt från tidvattenmätningar vid Tasiusaq. Extra uppmärksamhet har tilldelats sambandet mellan tidvatten och depositionsmiljö i samband med havsnivåförändringarna. Resultaten tyder på att det skedde en snabb regression på 26 m i området kring Tasiusaq mellan 8750 and 8050 cal. år BP, ca 1000 år senare än vid kusten. Den relativa havsnivån föll under dagens nivå ca 8050 cal. år BP. Den relativa havsnivån fortsatte att falla till minst 3,5 m under högsta astronomiska tidvattennivån där den befann sig mellan 7300 och 1210 cal. år BP. En havsnivå motsvarande dagens nivå nåddes igen någon gång under de senaste 500 åren. Högsta kustlinjen vid Tasiusaq beräknades till ca 40 m över högsta astronomiska tidvattennivån. Jämförelser av högsta kustlinjen i Bredefjordsområdet indikerar att mycket av landhöjningen skedde innan området kring Tasiusaq var helt deglacierat. Även transgressionen skedde några tusen år senare i Tasiusaqområdet än vid kusten, trots att Tasiusaq befinner sig närmare Grönländska inlandsisen. Denna anomali kan förklaras genom att områdena påverkades olika mycket av den Neoglaciala isexpansionen och den landsänkning/landhöjning som förekom i perferin av den Nordamerikanska inlandsisen.Populärvetenskaplig sammanfattning: Havsnivåförändringar på södra Grönland. Den globala havsnivån har förändrats under den nuvarande mellanistiden främst på grund av fördelningen av vatten mellan hav och glaciärer. Den relativa havsnivån på södra Grönland påverkas också till stor del av jordskorpans anpassning till storleken på det grönländska istäcket. I denna studie presenteras en ny strandförskjutningskurva från inre delen av Bredefjorden på södra Grönland som visar hur den relativa havsnivån har förändrats under nuvarande mellanistid. Resultaten bygger i huvudsak på studier av sediment från botten av en marin lagun. Havsnivåförändringar kan registreras på botten av sjöar och marina laguner, t.ex. genom förändring av floran och faunan, på grund av övergångar från söt- till saltvatten (eller tvärt om). Övergångarna kan tidsbestämmas genom datering av organiskt material med kol 14-metoden. Extra uppmärksamhet har i arbetet tilldelats sambandet mellan tidvatten och depositionsmiljö i samband med havsnivå¬förändringarna. Resultaten visar att havsnivån föll snabbt i området mellan 9000 och 8000 år före nutid, som respons på jordskorpans anpassning till en mindre inlandsis. Resultaten visar också att den relativa havsnivån befann sig på en lägre nivå än dagens havsnivå större delen de senaste 8000 åren. Den högsta kustlinjen – den högsta nivå som havet nått i området – bestämdes till ca 40 m över dagen havsnivå. Jämförelser av högsta kustlinjen på södra Grönland indikerar att mycket av landhöjningen skedde i inre Bredefjorden innan området var helt deglacierat. Resultaten indikerar dessutom att den relativa havsnivån på södra Grönland inte bara påverkas av inlandsisen in dess närhet, utan även av den Nordgrönländska- och den Nordamerikanska inlandsisen.Until recently there have only been a few observations of relative sea-level change from the inner Bredefjord area in southern Greenland. Here a new sea-level curve is presented from the Tasiusaq area based on data mainly from a sediment sequence from a marine embayment. Sea-level changes can be recorded in sediments as changed chemical composition, physical properties and macrofossil content. Isolation and transgression sequences have been identified using lithology, loss on ignition, XRF and macrofossil analysis. Selected stratigraphical levels were AMS-dated, and additional sea level data was extracted from GPS and tidal measurements. Special attention has been given to the relation between tide and depositional environment during sea-level changes. The results suggest a rapid regression of 26 m in the Tasiusaq area between 8750 and 8050 cal. yr BP, about 1000 years later than at the coast. The sea level fell below present day level at 8050 cal. yr BP. The regression continued and the sea level reached below 3.5 m below highest astronomical tide (m b.h.a.t.) at 7300 cal. yr BP where it remained until 1210 cal. yr BP. The present day sea level was reached again sometime during the last 500 years. The marine limit was determined to c. 40 m above highest astronomical tide (m a.h.a.t.). Comparisons of the marine limit in the Bredefjord area suggest that much of the land uplift occurred before the Tasiusaq area was finally deglaciated. The transgression started also more than 2000 years later in Tasiusaq than at the coast, despite the fact that Tasiusaq is situated closer to the Greenland Ice Sheet. This anomaly can be explained by differential effects from the collapse of the Laurentide Ice Sheet peripheral bulge and the Neoglacial readvance