Late Holocene vegetation, fire, climate and upper forest line dynamics in the Podocarpus National Park, southeastern Ecuador

Late Holocene vegetation, fire, climate and upper forest line dynamics were studied based on detailed pollen and charcoal analyses. Two sediment cores, from the Rabadilla de Vaca mire (RVM) and the Valle Peque?o bog (VP), with an age of about 2100 and 1630 cal yrs b.p., respectively, were taken at the modern upper forest line in the Parque Nacional Podocarpus (Podocarpus National Park) in southeastern Ecuador. The two pollen records reflect relatively stable vegetation with slight changes in floral composition during the recorded period. Changes of the proportion between subpáramo and páramo vegetation are related to lower and higher frequency of fires. The RVM records show that the upper forest line moved to a higher elevation between 1630 and 880 cal yrs b.p., stabilising after 310 cal yrs b.p. Human impact is suggested by a high fire frequency, mainly between 1800–1600 and 880–310 cal yrs b.p. The VP records indicate no marked changes in the upper forest line. The charcoal records suggest an increased human impact from 230 cal yrs b.p. to the present. The results indicate that high fire frequency is an important factor in reducing the expansion of subpáramo vegetation and upper montane rainforest and in favouring the distribution of grass páramo. Since there is a clear correlation between fire and vegetation dynamics, it is difficult to detect how far climate change also played a significant role in upper forest line changes during the late Holocene.     

Prehistoric Pinus woodland dynamics in an upland landscape in northern Scotland: the roles of climate change and human impact

Pollen, microscopic charcoal, palaeohydrological and dendrochronological analyses are applied to a radiocarbon and tephrochronologically dated mid Holocene (ca. 8500–3000 cal b.p.) peat sequence with abundant fossil Pinus (pine) wood. The Pinus populations on peat fluctuated considerably over the period in question. Colonisation by Pinus from ca. 7900–7600 cal b.p. appears to have had no specific environmental trigger; it was probably determined by the rate of migration from particular populations. The second phase, at ca. 5000–4400 cal b.p., was facilitated by anthropogenic interference that reduced competition from other trees. The pollen record shows two Pinus declines. The first at ca. 6200–5500 cal b.p. was caused by a series of rapid and frequent climatic shifts. The second, the so-called pine decline, was very gradual (ca. 4200–3300 cal b.p.) at Loch Farlary and may not have been related to climate change as is often supposed. Low intensity but sustained grazing pressures were more important. Throughout the mid Holocene, the frequency and intensity of burning in these open Pinus–Calluna woods were probably highly sensitive to hydrological (climatic) change. Axe marks on several trees are related to the mid to late Bronze Age, i.e., long after the trees had died.     

Vegetation changes during the Slavic period, shown by a high resolution pollen diagram from the Maujahn peat bog near Dannenberg, Hanover Wendland, Germany

In the Maujahn peat bog the Slavic period is recorded with a high-resolution pollen diagram in 150 cm of the peat profile. In the upper part of the pollen diagram the time resolution is 3.2 years in the middle and lower part 5.2 years. The Slavic period can be divided into four stages according to different kind of land use and intensity of human influence. The main crop was Secale; less important was the cultivation of Triticum, Panicum, Hordeum, Avena and Pisum. The Slavic period lasted from about a.d. 800–1200. The pollen diagram also displays a final part of the Migration period.     

Raised peat bog development and possible responses to environmental changes during the mid- to late-Holocene. Can the palaeoecological record be used to predict the nature and response of raised peat bogs to future climate change?

Palaeoecological analyses of raised peat bog deposits in northwest Europe show the naturalness, antiquity and robust response of these ecosystems to environmental changes from c. 7800 years ago to the present. A review of the techniques used to identify these long-term features is presented and the role of climate change, autogenic change processes and human disturbance is discussed. Millennial records of vegetation changes recorded in peat deposits demonstrate the response (often rapid) of raised peat bog vegetation to climatic changes during the mid-Holocene, Bronze Age/Iron Age transition and the Little Ice Age. Greenhouse warming scenarios exceed the reconstructed Holocene record of climatic changes (c. the last 11, 500 years), and bog-water tables may fall considerably. A combination of centennial palaeoecological analyses of bogs affected by human disturbance and experimental manipulations have been used as analogues for the potential response of raised peat bog vegetation to these changes. These show that possible greenhouse gas climate forcing scenarios may exceed the ability of Sphagnum- dominated raised peat bogs to respond to projected increases in summer temperature and decreases in summer precipitation. In combination with increasing N deposition, a loss of their Sphagnum-rich vegetation and increases in the abundance of vascular plants could occur on decadal timescales.     

The Effects of Permafrost Thaw on Soil Hydrologic, Thermal, and Carbon Dynamics in an Alaskan Peatland

Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior Alaska. We observed dramatic changes in the distribution of soil water associated with thawing of ice-rich frozen peat. The impoundment of warm water in collapse-scar bogs initiated talik formation and the lateral expansion of bogs over time. On average, Permafrost Plateaus stored 137 ± 37 kg C m⁻², whereas OC storage in Young Bogs and Old Bogs averaged 84 ± 13 kg C m⁻². Based on our reconstructions, the accumulation of OC in near-surface bog peat continued for nearly 1,000 years following permafrost thaw, at which point accumulation rates slowed. Rapid decomposition of thawed forest peat reduced deep OC stocks by nearly half during the first 100 years following thaw. Using a simple mass-balance model, we show that accumulation rates at the bog surface were not sufficient to balance deep OC losses, resulting in a net loss of OC from the entire peat column. An uncertainty analysis also revealed that the magnitude and timing of soil OC loss from thawed forest peat depends substantially on variation in OC input rates to bog peat and variation in decay constants for shallow and deep OC stocks. These findings suggest that permafrost thaw and the subsequent release of OC from thawed peat will likely reduce the strength of northern permafrost-affected peatlands as a carbon dioxide sink, and consequently, will likely accelerate rates of atmospheric warming.     

Persistent versus transient tree encroachment of temperate peat bogs: effects of climate warming and drought events

Peatlands store approximately 30% of global soil carbon, most in moss‐dominated bogs. Future climatic changes, such as changes in precipitation patterns and warming, are expected to affect peat bog vegetation composition and thereby its long‐term carbon sequestration capacity. Theoretical work suggests that an episode of rapid environmental change is more likely to trigger transitions to alternative ecosystem states than a gradual, but equally large, change in conditions. We used a dynamic vegetation model to explore the impacts of drought events and increased temperature on vegetation composition of temperate peat bogs. We analyzed the consequences of six patterns of summer drought events combined with five temperature scenarios to test whether an open peat bog dominated by moss (Sphagnum) could shift to a tree‐dominated state. Unexpectedly, neither a gradual decrease in the amount of summer precipitation nor the occurrence of a number of extremely dry summers in a row could shift the moss‐dominated peat bog permanently into a tree‐dominated peat bog. The increase in tree biomass during drought events was unable to trigger positive feedbacks that keep the ecosystem in a tree‐dominated state after a return to previous ‘normal’ rainfall conditions. In contrast, temperature increases from 1 °C onward already shifted peat bogs into tree‐dominated ecosystems. In our simulations, drought events facilitated tree establishment, but temperature determined how much tree biomass could develop. Our results suggest that under current climatic conditions, peat bog vegetation is rather resilient to drought events, but very sensitive to temperature increases, indicating that future warming is likely to trigger persistent vegetation shifts.     

Accumulation and attrition of peat soils in the Australian Alps: Isotopic dating evidence

Bog peat soils have been accumulating at Wellington Plain peatland, Victoria, Australia for the last 3300 years. Now, dried peat soils are common adjacent to bog peats. The ¹⁴C basal age of dried peat is not different from the ¹⁴C basal age of bog peat, which supports the theory that dried peat formed from bog peat. A novel application of ²¹⁰Pb dating links the timing of this change with the introduction of livestock to Wellington Plain in the mid‐1800s. Physical loss of material appears to have been the dominant process removing material as bog peats drained to form dried peats, as indicated by the mass balances of carbon and lead. This research has implications for the post‐fire and post‐grazing restoration of bogs in Victoria's Alpine National Park, and the contribution of peat soils to Australia's carbon emissions.     

Four thousand years of vegetation and fire history in the spruce forests of northern Kyrgyzstan (Kungey Alatau,Central Asia)

Analyses of pollen, macrofossils and microscopic charcoal in the sediment of a small sub-alpine lake (Karakol, Kyrgyzstan) provide new data to reconstruct the vegetation history of the Kungey Alatau spruce forest during the late-Holocene, i.e. the past 4,000 years. The pollen data suggest that Picea schrenkiana F. and M. was the dominant tree in this region from the beginning of the record. The pollen record of pronounced die-backs of the forests, along with lithostratigraphical evidence, points to possible climatic cooling (and/or drying) around 3,800 cal year b.p. and between 3,350 and 2,520 cal year b.p., with a culmination at 2,800–2,600 cal b.p., although stable climatic conditions are reported for this region for the past 3,000–4,000 years in previous studies. From 2,500 to 190 cal year b.p. high pollen values of P. schrenkiana suggest rather closed and dense forests under the environmental conditions of that time. A marked decline in spruce forests occurred with the onset of modern human activities in the region from 190 cal year b.p. These results show that the present forests are anthropogenically reduced and represent only about half of their potential natural extent. As P. schrenkiana is a species endemic to the western Tien Shan, it is most likely that its refugium was confined to this region. However, our palaeoecological record is too recent to address this hypothesis thoroughly.     

The Auchenorrhyncha fauna of peat bogs in the Austrian part of the Bohemian Forest (Insecta,Hemiptera)

The first overview on the Auchenorrhyncha fauna of peat bogs of the Austrian Bohemian Forest is presented. Seven oligotrophic peat bog sites were studied in 2011 by suction sampler (“G-Vac”) and 93 Auchenorrhyncha species (with 7465 adult specimens) were recorded. Eleven species (about 18 % of the individuals) are tyrphobiontic or tyrphophilous. The relative species abundance plot is not very steep; the six most abundant species represent 50 % of the individuals. The most common species is Conomelus anceps (17 % of the individuals). Compared to the whole Austrian Auchenorrhyncha fauna, the fauna of peat bogs comprises distinctly more univoltine species and more species hibernating in nymphal stage. Densities of adult Auchenorrhyncha in peat bogs are low in spring (about 10–60 individuals per m²) and high in July, with up to 180 (±50) individuals per m². Disturbed peat bogs have higher species numbers and higher Auchenorrhyncha densities in total, but lower numbers and densities in peat bog specialists.     

7500 yr of mire-pool development and the history of Pinus sylvestris (L.) in Sub-Arctic coastal Norway

In coastal North Norway, mire areas and mire pools frequently exist, but their development and time of origin are poorly known. In order to investigate the development of a coastal mire pool and relate its changes to known climatic changes, a sediment sequence from the mire-pool Lillevardhaugvatnet (c. 0.05 ha large), was ¹⁴C-dated, investigated for loss on ignition and analysed for pollen and botanical macrofossils.The bottom of the sequence dates c. 7500 cal. BP. The site gradually developed from a swamp forest c. 6200 cal. BP via a more open dwarf-shrub phase to a pool c. 5000 cal. BP. The pool grew in depth as the result of continuous peat growth damming the water body. The water level of the pool was probably lowered by erosional drain c. 2700 cal. BP. Redeposited peat in the sequence occurred c. 2100 cal. BP and c. 1100 cal. BP. ¹⁴C-dates and pollen indicate that erosion and redeposition of the peat surrounding the mire pool is a normal process, connected with the expansion of the water body.The combination of macrofossils and pollen accumulation rates (PAR) of P. sylvestris indicates that in small lakes in coastal areas of North Norway, a PAR of 200–400 cm^− 2 yr^− 1 is sufficient for indicating local presence of P. sylvestris. P. sylvestris is represented with abundant macrofossils between 4800 and 2100 cal. BP. It is suggested that a marked P. sylvestris decrease about 2100 cal. BP may be a combined effect of human impact and climatic deterioration. A possible final termination of the P. sylvestris population about 1600 cal. BP may be considered human-made.     

Vegetation history,climate and human impact over the last 15,000 years at Lago dell’Accesa (Tuscany,Central Italy)

Interdisciplinary studies of the sediments of Lago dell’Accesa started in 2001. We present here results from the palynological study. The pollen diagram provides a record of vegetation and climatic change spanning over 15,000 years. The oldest pollen spectra show a late-glacial steppe vegetation typical of central and southern Italy during this period. The Late-glacial Interstadial, interrupted by two cooling events, is dominated by open deciduous oak forests. The Younger Dryas is represented by 150 cm of sediment and shows the presence of steppic vegetation. The Holocene vegetation is characterised by alternating dominance of deciduous oaks and Quercus ilex. The three zones characterised by Q. ilex are accompanied by peat layers marking lake-level lowering at ca. 8600–7900, 4600–4300 and 3700–2800 cal b.p. Between approximately 9000 and 6000 cal b.p. extensive Abies-forests existed on the Colline Metallifere located 15–20 km to the north and northeast of the lake. Local fir populations may also have existed by the lake. Human impact starts at approximately 8000 cal b.p. during the Neolithic period, and increases at ca. 4300 cal b.p. Castanea and Juglans pollen is recorded from ca. 2800 cal b.p. The impact of the Etruscan settlement near the lakeshore is shown in the increasing values of arable crops, species of secondary forest canopy (Ericaceae, Pinus, Pistacia, Myrtus) and anthropogenic indicators (Chenopodiaceae, Plantago lanceolata, Rumex etc).     

A Holocene environmental record reflecting vegetation, climate, and fire variability at the Páramo of Quimsacocha, southwestern Ecuadorian Andes

We reconstructed the palaeoenvironmental conditions of the last ca. 8,000 years in the Tres Lagunas region of the Quimsacocha volcanic basin (ca. 3,800 m a.s.l.) in the southwestern Ecuadorian Andes. By means of a pollen and charcoal record, we analysed vegetation, fire, and climate history of this area, which is sensitive to climatic changes of both the Pacific as well as of the eastern Andes and Amazon region. Sediment deposits, pronounced increases of pollen and charcoal concentrations, and pollen taxa reflect warmer and drier conditions in the early to mid-Holocene (~8000 to 3900 cal. b.p.). During the late Holocene (2250 to −57 cal. b.p.), five warm and cold phases occurred at Quimsacocha. The most prominent cold phase possibly corresponds to the globally recognized Little Ice Age (LIA; ~600 to 100 cal. b.p.). The cold phase signal at Quimsacocha was characterized by a higher abundance of Poaceae, Iso?tes and Gentianella, which are favoured by cold and moist conditions. Frequent charcoal particles can be recorded since the early to mid-Holocene (~7600 b.p.). The high Andean tree species Polylepis underwent several phases of degradation and re-establishment in the basin, which could indicate the use of fire by pre-Columbian settlers to enhance the growth of preferred herb species. The Tres Lagunas record suggests that human populations have been influencing the environment around Quimsacocha since the last ca. 8,000 years.     

Patterns of variation in morphological characters and isoenzymes in populations of Sphagnum capillifolium (Ehrh.) Hedw. and S. rubellum Wils. from two bogs in southern Sweden

Abstract

Isoenzymatic and morphological data of four populations from two bogs in southern Sweden are presented. From each bog one population of Sphagnum rubellum was sampled from the mire expanse and one population of S. capillifolium from the mire margin. Data from isoenzyme-electrophoresis show that there is agenetic difference corresponding to the two morphological taxa. It is also indicated that they may hybridize. The fact that the taxa seem to be better separated at the continental Aggarps Mosse than at the suboceanic Traneröds Mosse would suggest that hybridization occurs more often in coastal than in inland climates.     

POLLEN SUCCESSION,ABSOLUTE POLLEN FREQUENCY,AND RECURRENCE SURFACES IN CENTRAL JAPAN

A generalized pollen diagram, associated with three simplified pollen diagrams from Tsubogakure (1,500 m), Nakatashiro (1,400 m) and Yashima-ga-hara (1,650 m) bogs in central Japan, represents five pollen zones for the last 12,000 years, i.e., L (before 10,500 B.P., pine-boreal); R I (10,500–9,500 B.P., boreal-oak); R II (9,500–4,500 B.P., temperate); R IIIa (4,500–1,500 B.P., temperate-boreal); and R IIIb (after 1,500 B.P., pino-nonarboreal). Absolute pollen frequency is high in well-humified peat, in gyttja (deposited immediately below the first peat formation), and in peat in the part of the R IIIa cooling stage, and it is low in less-humified peat, since the former sediments have slow and the latter rapid rates of accumulation, respectively. Changes of plant communities should affect the absolute pollen frequency, but changes of sedimentation rates are more critical. After a re-examination of Nakatashiro bog, it is hardly possible to recognize a recurrence surface in the European sense, nor can the accumulation of thin tephra on the bog surface be responsible for a temporary halt in peat growth. Nakatashiro bog (like Tsubogakure bog) is a low-moor bog, and true recurrence surfaces would not be expected in it. In a raised Yashima-ga-hara bog, however, there are seven recurrence surfaces without a volcanic ash band; the well-humified horizons correspond to low values of Sphagnum spores and Cyperaceae pollen, and the less-humified horizons to high values of Sphagnum spores and Cyperaceae pollen. Peaks of these species in the upper core correspond to those Cryptomeria pollen, an indicator of the high precipitation (generally >1,800 mm/yr). Regularly interrelated fluctuations among these species, absolute pollen frequency, and peat horizons suggest that the precipitation was low in well-humified peat and was high in less-humified peat.     

Linking past cultural developments to palaeoenvironmental changes in Estonia

Connections between environmental and cultural changes are analysed in Estonia during the past c. 4,500 years. Records of cereal-type pollen as (agri)cultural indices are compared with high-resolution palaeohydrological and annual mean temperature reconstructions from a selection of Estonian bogs and lakes (and Lake Igelsjön in Sweden). A broad-scale comparison shows increases in the percentage of cereal-type pollen during a decreasing trend in annual mean temperatures over the past c. 4,300 years, suggesting a certain independence of agrarian activities from environmental conditions at the regional level. The first cereal-type pollen in the region is found from a period with a warm and dry climate. A slow increase in pollen of cultivated land is seen around the beginning of the late Bronze Age, a slight increase at the end of the Roman Iron Age and a significant increase at the beginning of the Middle Ages. In a few cases increases in agricultural pollen percentages occur in the periods of warming. Stagnation and regression occurs in the periods of cooling, but regression at individual sites may also be related to warmer climate episodes. The cooling at c. 400–300 cal b.p., during the ‘Little Ice Age’ coincides with declines in cereal-type and herb pollen curves. These may not, however, be directly related to the climate change, because they coincide with war activities in the region.     

Human impact signals from peat bogs – a combined palynological and geochemical approach

This research compares palynological evidence for changes in land use histories with a geochemical method for reconstructing past soil erosion. Changes in land use have significant effects on soil erosion. It has been shown elsewhere that silicon (Si) and titanium (Ti) are good proxies for soil erosion. Ombrotrophic peat bogs are useful archives in which to measure Si and Ti depositions as they only receive inorganic erosional inputs through atmospheric deposition and they contain very low background levels of mineral matter. The correlation between geochemical and pollen analytical reconstructions of past human activity from three raised bog sites in Great Britain and Ireland is discussed here, with reference to examples from four particular time periods: the mid-to-late Bronze Age/Iron Age, the late Iron Age/Roman period, the Middle Ages/Tudor period and the more recent past. The results generally indicate a close correlation between the palynological and geochemical proxies, with the combination of both methods allowing a more comprehensive interpretation of the palaeoenvironmental record. Plantago lanceolata and Poaceae pollen frequencies appear to correlate particularly well with the geochemical proxies. A multi-proxy approach such as this may be particularly useful for identifying and interpreting low-level prehistoric human impact.     

The butterfly fauna of Wisconsin bogs: lessons for conservation

During 2002–2009, we surveyed butterflies at 73 bogs, 20 adjacent lowland roadsides, and 5 nearby upland roadsides in northern Wisconsin and three bogs in central Wisconsin, with additional observations from 1986 to 2001. Especially in northern Wisconsin, bogs are relatively unaffected by humans, but naturally comprise <1% of the landscape. Bog specialist species composition varied by bog type (muskeg, kettlehole, coastal peatland). Specialist abundance also varied significantly both among bog types and within type among sites. A number of bog specialists frequently occurred in numerous examples of bogs, including all three types. But virtually no specialist individuals occurred in nearby upland roadsides. Northern Wisconsin bogs had similar specialist species richness compared to large barrens and heaths in the same region. Specialist species comprised a small proportion (10%) of all butterfly species recorded in bogs, similar to proportions reported for specialists in tallgrass prairie and barrens. However, specialists accounted for nearly half the total individuals recorded in bogs, comparable to proportions of specialists found in less fragmented vegetation (barrens) and larger patches of favorably managed prairie, but far exceeding proportions observed in other highly fragmented prairie patches. A fundamental lesson may be that aiming to conserve typical ecosystems, even if native, and their average processes, leads to average (generalist) butterflies. Bogs have different vegetation types superimposed on each other, including bog, heath, forest, sedge meadow, and wet meadow associates in the same spots. Conservation management needs to avoid simplifying the vegetation to one layer, reducing specialist fauna. Long-term vegetative consistency, as in bogs, is advised for conservation management of specialist butterflies in other fragmented vegetations.     

The mid-Holocene extinction of silver fir (Abies alba) in the Southern Alps: a consequence of forest fires? Palaeobotanical records and forest simulations

Pollen records suggest that Abies alba played a dominating role in both the montane and lowland forests at the border of the Southern Alps between ca. 8500 and 5700 years ago. Two major declines in fir, at about 7300–7000 cal b.p. and at ca. 6000 cal b.p., followed by the local extinction of the species are characteristic of the area below ca. 1000 m a.s.l. In order to test the impact of fire on the population dynamics of silver fir, a dynamic model (DisCForm) with a fire module was applied to simulate the early- and mid-Holocene forest development. Simulation outputs based on different fire scenarios were compared with the pollen record from Lago di Annone (226 m a.s.l.). The marked Abies decreases shown in the pollen record can be simulated with very intensive fire scenarios, but they do not result in an extinction of silver fir in the model. Low charcoal influx values related to the Abies declines in the palaeobotanical record suggest that fire was not the only reason for the extinction of silver fir. Human impact, as well as Holocene climatic changes leading to temporary moisture deficits and reduced adaptability due to low genetic variation may have had a significant impact on the Abies forests.     

From forest to open pastures and fields: cultural landscape development in western Norway inferred from two pollen records representing different spatial scales of vegetation

The cultural landscape development of a farming community in western Norway was investigated through pollen analyses from a lake and a peat/soil profile. The pollen record from the lake indicates that there was a decrease in arboreal pollen (AP) by the end of the Mesolithic period (ca. 4200 cal b.c.), and that a substantial forest clearance occurred during the Bronze Age (ca. 1500 cal b.c.). The latter, together with grazing indicators and cereals, suggests a widespread establishment of farming. At the beginning of the Roman Iron Age there is an increase in heath communities. The pollen diagram from the peat/soil profile shows the forest clearance in the Bronze Age more clearly than the lake profile. This local pollen diagram is compared with modern pollen samples from mown and grazed localities in western Norway. Both analogue matching and ordination (PCA) indicate that the site was characterised by pastures and cereal fields from the Late Bronze Age to the Late Iron Age. An expansion of cereal cultivation took place during the Pre-Roman Iron Age, and an arable field was established at the site after ca. a.d. 800. This investigation illustrates the potential of selecting pollen sites reflecting different spatial scales, and complements the cultural history of the area as inferred from archaeological and historical records.     

Holocene environmental history of Lake Vuolep Njakajaure (Abisko National Park, northern Sweden) reconstructed using biological proxy indicators

Holocene environmental and climatic changes are reconstructed using analyses of biological proxies in lake sediments from Vuolep Njakajaure, a lake located near the altitudinal treeline in northern Sweden (68°20′ N, 18°47′ E). We analysed biological proxy indicators from both aquatic and terrestrial ecosystems, including diatoms, pollen and chironomid head capsules, in order to reconstruct regional Holocene climate and the development of the lake and its catchment. During the early Holocene and after 2500 cal b.p., Fragilaria taxa dominated the diatom assemblages, whereas planktonic Cyclotella taxa prevailed during the major part of the Holocene (7800–2300 cal b.p.), indicating the importance of the pelagic habitat for diatom assemblage composition. The planktonic diatoms appeared at the same time as Alnus became established in the catchment, probably altering nutrient availability and catchment stability. The pollen record is dominated by mountain birch (Betula pubescens ssp. tortuosa) pollen throughout the Holocene, but high percentage abundances of Scots pine (Pinus sylvestris) pollen suggest the presence of a mixed pine-birch forest during the mid-Holocene (6800–2300 cal b.p.). Head capsules of Tanytarsini and Psectrocladius dominated the chironomid assemblage composition throughout the Holocene, in combination with Corynocera ambigua after 2300 cal b.p. A quantitative, diatom-based reconstruction of mean July air temperature indicated a relatively cold temperature during the early Holocene (9000–8000 cal b.p.) and after ca. 2300 cal b.p., whereas the mid-Holocene period is characterised by stable and warm temperatures. The overall patterns of Holocene climate and environmental conditions are similarly described by all biological proxy-indicators, suggesting relatively warm conditions during the mid-Holocene (ca. 7800–2300 cal b.p.), with a subsequent colder climate after 2300 cal b.p. However, the onset and magnitude of the inferred changes differ slightly among the proxies, illustrating different responses to lake development phases, land-uplift, and climate forcing (e.g., insolation patterns) during the Holocene in northern Sweden.