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Bioclimatic architecture strategies and solar active systems contribute strongly to the reduction of building energy demand and achieving thermal comfort for its occupants over the whole year. This paper deals with the study of the energy performance improvement of a pilot bioclimatic house located in Algiers (Algeria). First, a series of experimental measures are conducted during cold period to show the effect of passive and active solar gains on the improvement of the indoor air temperature of the house. Then, a dynamic model of a solar heating system coupled with a bioclimatic house has been developed using TRNSYS software and validated with experimental data. The validated model has been used to establish the energy balance of the pilot bioclimatic house without solar heating system and to compare them to those of a conventional house. Finally, the improvement of the energy balance of the pilot bioclimatic house has been done by passive and active ways. The passive one includes the increase of south facing windows size and the use of night cooling with the use of shading device in summer. The active one consists of the integration of a solar heating system. Furthermore, an environmental study has been performed. The experimental results show that the energy requirements of a pilot bioclimatic house are very low which is suitable for the use of solar heating system in building. The simulation results show that the application of bioclimatic strategies is a better way to provide thermal comfort in summer and decrease the space heating energy demand of the house with 48.70%. The active solar system will cover 67.74% of the energy demand for heating of the house. These energy savings generate a significant reduction in CO2 emissions.Practical application: This work will enable engineers and designers of modern buildings of buildings in a Mediterranean climate to improve building energy efficiency and reduce CO2 emissions by a conjunction of different passive heating and cooling techniques such as insulation, thermal mass, window shades, night ventilation, and the solar heating system. The paper provides designers an effective strategy in terms of energy savings and indoor thermal comfort while reducing CO2 emissions. [ABSTRACT FROM AUTHOR]

Almost a century ago, observed geographic patterns of plant phenology (such as leaf-out and flowering) were summarized in Hopkins' Bioclimatic Law. This law describes phenology as varying along climatic gradients by latitude, longitude, and altitude. Yet phenological patterns are not only affected by contemporary climatic differences across space, but also by underlying geographic variations in plant genetics that arise from longterm climatic adaptation. The latter influence on geographic patterns in phenology has been undervalued to this day, mainly due to the difficulty of quantifying it. This study outlines a methodology for bridging this knowledge gap through delineating geographic adaption patterns using common garden and cloned plant phenology. Through synthesizing existing literature, typical geographic adaptation patterns in both spring and autumn phenology of many temperate tree species are identified. Under uniform environment, spring leafout of colder climate-adapted populations of a certain species is either earlier than warmer climate-adapted ones due to lower thermal requirements, or later because of higher chilling (for dormancy release) demands. The former leads to a countergradient pattern as it is opposite to an in situ observation, while the latter leads to a cogradient pattern. Autumn leaf senescence, on the other hand, expresses a consistent cogradient pattern that is related to latitude and constrained by the populations' varied photoperiod requirements. These geographic adaptation patterns allow a clearer understanding of geographical variations in phenological responses to climate change, and provide a theoretical basis for spatially explicit phenological models. In addition, given that these adaptive patterns reveal genotype-based variabilities, they are potentially useful for more accurately tracking phenology-dependent ecosystem processes (e.g. species distribution) and nonweather- related vegetation changes. As a unique subfield of physical geography with broad environmental implications, this line of research needs to be further developed by furnishing a stronger and more explicit spatial structure into current phenological studies. [ABSTRACT FROM AUTHOR]

This research is a design and assessment of a bioclimatic house wall and roof to be constructed in Thailand’s housing market in order to provide information for potential builders as well as the peace of mind of the owner. The research found that a bioclimatic house with a double-layered solar chimney is appropriate for use in Thailand throughout the year. It lowers the average internal temperature of the house by approximately 1–2℃ when compared to the energy-saving material used in a normal building. Bioclimatic construction also creates natural ventilation, heat removal, and can reduce indoor temperature. It also comes with an easy-to-build design to facilitate construction and can save house energy consumption.Practical application: This research provides helpful information of solar chimney wall and roof for both the owners and developers in adopting an energy-efficient house for sustainable energy conservation. A solar chimney of a bioclimatic house is a highly interesting alternative for saving energy in the long term. When properly promoted, it will help save a huge amount of energy throughout Thailand and tropical area, and serve to promote the cause of global environmental conservation into the future. [ABSTRACT FROM AUTHOR]

Human biometeorology is experiencing resurgence because of concerns about the impact of weather and climate on living organisms and the effects of human activities on the atmospheric environment. The purpose of this progress report is to review recent research in three strongly emergent areas of human biometeorology, namely human thermal comfort assessment, ultraviolet radiation (UVR) and climate and vector borne disease. Within the field of human thermal comfort assessment there is evidence of a shift away from empirical two-variable to numerically solved human heat budget based indices for assessing human thermal comfort, although the former are still applied widely. Recent research activity concerning UVR has focused on the evaluation of measurement error, the examination of controlling factors, the reconstruction of long-term records using a variety of methods for the analysis of UVR trends and variability and climate change related projections of future UVR levels. While for some regions clear evidence has emerged of an association between climate and vector borne disease, for other regions the situation is unclear or complex. This poses a challenge for developing climate-based early warning systems for diseases such as malaria and dengue and making projections of the potential impacts of climate change on the geographic range and magnitude of VBD. From the material reviewed in this progress report it is clear that human biometeorology fits comfortably within physical geography as it addresses many of the issues aligned with the human-environment, spatial and earth science traditions of physical geography. [ABSTRACT FROM AUTHOR]

The urban heat island effect and its consequences is one of the most important problems cities worldwide have to face in an effort to become more sustainable. This paper presents a study of a major open area in a densely built and populated area in the centre of Athens that was part of a Municipality of Athens program to improve thermal comfort conditions in open spaces. The bioclimatic rehabilitation design process was based on a specific strategy involving detailed monitoring of the thermal characteristics and climatic conditions in the area, extensive analysis of the results in order to define the problem, design and use of efficient passive cooling techniques (cool materials, green spaces, solar control and earth to air heat exchangers), and the use of advanced simulation tools to evaluate and optimise the planed microclimatic improvements. The results indicate that the proposed measures contribute to a decrease in local temperatures of up to 2°C for summer conditions.Practical application:• The knowledge on perceptions of microclimate in outdoor space can serve as a basis for urban spatial design.• To evaluate the application of cool materials in public urban squares.• Strategies to improve local microclimate with monitoring and modelling the design features. [ABSTRACT FROM PUBLISHER]

Regional and national parks have been created to preserve biodiversity and quasi-natural ecosystems, but uncertainties about local environmental history hinder the assessment of important nature-conservation baselines (e.g. natural vegetation composition, role of human activities). We use pollen, plant macrofossils, microcharcoal and radiocarbon dating to reconstruct the environmental dynamics at two mires in the mountain belt of southern Switzerland (Segna and Piano). Two major vegetation changes occurred during the past 3000 years: (1) Picea abies, Abies alba and Fagus sylvatica forests developed into monospecific beech forests and (2) F. sylvatica was reduced and open land expanded. The first change occurred at AD 450 at Segna and AD 1500 at Piano, the second at AD 1600-1700 at both sites. At Segna the A. alba decline occurred during a relatively warm and dry period when local fires and human impact increased. Similarly, at Piano the shift to Fagus-dominated forests was probably induced by human impact. The final decline of F. sylvatica and expansion of open land is clearly related to an intensification of human activities at both sites. Our results suggest a pronounced sensitivity of A. alba to human disturbance in the mountain belt and show that biodiversity is positively related to land use, while human activities decisively reduced woodland diversity. In conclusion, promoting natural succession and A. alba would significantly increase woodland diversity and may significantly contribute to stabilize forests under climatic conditions significantly warmer than today. Biodiversity conservation efforts should concentrate in areas where agriculture has a long history. [ABSTRACT FROM AUTHOR]

A 96-yr climate record (1908-2004), historical descriptions, multiyear (1950, 1964, 1978, 1994) lake-surface area measurements, and 1950 and 2004 physiognomically based vegetation maps were compiled to assess vegetation change in the Fox Lake area (4248 ha) within the lower Peace River district of northern Alberta. A climatic warming trend (r = 0.615, P < 0.001; 0.35°C/decade) was evident during the twentieth century, with peak precipitation occurring from 1970 to 1990. Five major wet-dry cycles, based on net water balance values (precipitation minus potential evaporation), were evident with peaks occurring at about 17(±3) year intervals. Each cycle became slightly less arid than the previous until the mid-1990s. Deciduous forests dominated upland sites in 2004, whereas deciduous shrub and juvenile tree stands comprised 78% in 1950. Total wetland area remained relatively constant between 1950 and 2004, but less meadow and more standing water were present in 2004. Lake-surface area changes suggested that wetlands were recharged by precipitation rather than floodwaters from the nearby Peace River. Low water availability and historical descriptions suggest grassland-dominated parkland-like vegetation occurred in the study area during the early part of the twentieth century, with upland shrubs replacing grasslands by 1950. Increased atmospheric water availability rather than cessation of aboriginal burning or natural fires was considered responsible for increased forest abundance after 1945. Greater aridity in response to future global warming could reduce the abundance of forests in the lower Peace River district, and shift the regional climate from a boreal to a grassland-dominated parkland climatic regime. [ABSTRACT FROM AUTHOR]

We studied the relationships between surface pollen spectra, vegetation and selected climate characteristics along a strong gradient of climate continentality across the Western Sayan Mountains, southern Siberia. Representation of 111 pollen taxa in 81 surface samples from steppe, forest and tundra was related to the vegetation composition at various distances from the sampling point and to mean annual precipitation and mean July and January temperatures. These relationships were assessed by the decision tree models. The results show (1) which vegetation types are well distinguished by their pollen spectra; (2) which vegetation types are strongly similar in their pollen spectra and therefore their interpretation from fossil pollen spectra should be carefully considered; (3) tight relationship between surface pollen spectra and selected climate characteristics, which suggests that the past climatic conditions can be reasonably predicted from pollen spectra; and (4) an important role of weak pollen producers for assignment of pollen spectra to vegetation types or particular values of temperature and precipitation. We found the decision trees suitable for analysis of pollen/vegetation relationship because they (1) formally and precisely assign the pollen spectra to vegetation/landscape types or climatic variables by means of easy-to-interpret graphs; (2) identify pollen taxa that are best indicators of a particular vegetation type, landscape or climate characteristics; and (3) utilize the pollen signal of both strong and weak pollen producers. We compare the decision tree models with ordination and cluster analysis and suggest further applications. [ABSTRACT FROM AUTHOR]

The Global Pollen Database is an example of a successful data synthesis effort that has uses for biogeographical and climate change studies. Results are of interest in many fields of physical geography. Continental-scale maps of past conditions have been used in data-model comparison studies. Time series, developed by averaging quantitative reconstructions from many sites, have indicated that millennial-scale climate variability has affected the vegetation of Europe and North America during the Holocene. Major transitions in the vegetation of Europe and North America occurred at the same time, suggesting the overriding climate effect on the vegetation of both continents. The database can also be used to test biogeographical hypotheses, as several examples illustrate, without the need for collecting new data. Hundreds of studies over the past 50 years show that pollen analysis is more precise than frequently acknowledged: vegetation responds rapidly to climate variations, changes in vegetation are spatially coherent and the taxonomic resolution available in the database is greater than frequently acknowledged. The availability of a public, freely available database enables different analyses to be performed on the same data, thereby ensuring that results are not dependent on methodology. [ABSTRACT FROM AUTHOR]

The capability of GPR (ground-penetrating radar) measurements to decipher the sedimentary history of young alluvial plains is investigated. The sediment basins result from the infill of two lakes, which were dammed by high-magnitude rockfalls 400-600 and 200 years ago in an Alpine trough valley. The thickness and structure of the dammed sediments was derived from a series of longitudinal and cross profiles. In order to take advantage of both high penetration and high resolution measurements, we applied 25, 50, 100 and 200 MHz antennas. The radargrams allow for a detailed analysis of the history of the alluvial fill. The pre-existing valley bottom is clearly visible under one of the basins. The profiles display the former clayey lake bottom and illustrate several stages of lake infill. Small-scale sedimentary structures, such as topset beds or foreset beds, are discernible and provide proxy information on water level, sediment supply and phases of infill activity. At the second basin, discordant structures in the adjacent sediment cones indicate the abrupt rise of the base level resulting from the rockfall event. Radar-derived information and historical records of lake retreat were used to reconstruct the sediment budget of the 200 year lifespan of the younger alluvial plane. Therefore, it can be concluded that the sedimentation rates of the twentieth century (489 ± 87 m3/yr) are several times larger than those of the nineteenth century (103 ± 7 m3/yr). A 130-yr rainstorm record suggests that the overall increase in sediment supply in the twentieth century corresponds to increased rainstorm frequencies during warm periods. [ABSTRACT FROM AUTHOR]

Pollen and high-resolution charcoal records from three lakes were examined to reconstruct the vegetation and fire history of the Oregon Coast Range for the last 9000 years. The sites are located along a north-to-south effective precipitation gradient and changes in vegetation and fire activity provided information on the nature of this gradient in the past. The relation of vegetation to climate change was examined at millennial timescales and the relation between fire and climate was examined on centennial timescales by comparing fire-interval distribution and fire synchrony between sites. The pollen data indicate more fire-adapted vegetation during the early-Holocene period (c. 9000 to 6700 cal. yr BP), followed by a shift to forests with more fire-sensitive taxa in the mid Holocene (c. 6700 cal. yr BP to 2700 cal. yr BP) and modern forest assemblages developing over the last c. 2700 years. Comparisons of fire-interval distributions showed that the time between fires was similar between two of the three combinations of sites, suggesting that the moisture gradient has played an important role in determining long-term fire frequency. However, century-scale synchrony of fire occurrence between the two sites with the largest difference in effective precipitation suggests that centennial-scale shifts in climate may have overcome the environmental differences between these locations. Asynchrony in fire occurrence between the sites with more similar effective precipitation implies that local conditions may have played an important role in determining fire synchrony between sites with similar long-term climate histories. [ABSTRACT FROM AUTHOR]

A number of large rock avalanches from the northern slope of the 1435 m high mountain of Vora in Breim, inner Nordfjord have been mapped. The avalanche tongues dam the 4 km long Sandalsvatnet, they cover an area of 3 km2 and the volume exceeds 100 million m3. Age estimates have been obtained by radiocarbon datings of rock dust layers in a bog and the Schmidt-hammer method. Altogether 11 large rock avalanches have occurred throughout the Holocene, of which six lobes can be recognized morphologically. Five silt laminae in a 5.5 m deep bog basin distally to the avalanche lobes are interpreted as primary sediments from dust clouds generated by rock avalanches. In addition three silt beds are interpreted as glaciolacustrine sediments related to temporary damming caused by landsliding. Average avalanche frequency during the Holocene was c. 1 per 1000 yr and during the period 7100-3600 BP it was c. 1 per 700 yr. After 3600 BP no rock avalanches have been recognized. [ABSTRACT FROM AUTHOR]

Vegetation and quantitative climate reconstructions from a northwestern France shelf core (VK03-58Bis) show orbital and suborbital climate variability for the last 8850 years in this region. A long-term cooling trend in summer temperatures, marked by gradual temperate and humid forest decline, parallels cooling in Greenland and the decrease of mid-latitude summer insolation reduction until at least 2000 cal. yr BP. At the long-term scale, the lowering in seasonal contrast revealed by vegetation changes follows the increase of precession. Corylus woodlands spread at the expense of deciduous Quercus forest, between 8740 and 8390 cal. yr BP, linked with the high seasonality conditions that, counterbalancing the long-term astronomical forcing trend, were amplified by the north Atlantic high-latitudes winter sea-ice expansion. High seasonality conditions resulted from the Agassiz and Ojibway final outburst episodes and consequent gradual reduction of the Meridional Overturning Circulation (MOC). Between 8390-8060 cal. yr BP, a sudden Corylus woodland decline marks the 8.2 kyr cold event in northwestern France probably triggered by the severe MOC reduction leading to the additional drop in winter temperature over Europe and Greenland. Nonetheless, seasonality remains high during this interval. The high seasonality conditions detected in 'VK03-58Bis' between 8740 and 8060 cal. yr BP reflects the multicentennial-scale climate cooling 8.6-8.0 kyr episode of the North Atlantic. Following the Agassiz and Ojibway final outburst episodes, climate became more stable. However, millennialscale climate cooling episodes are recorded in 'VK03-Bis' and are characterized by weak winter cooling and increases in precipitation. Furthermore, dinocyst analysis and benthic gastropod Turritella communis occurrences indicate regional changes such as the southward migration of the Boreal biogeographical zone between 8740 and 8480 cal. yr BP and the subsequent opening of the English Channel at around 8480-8390 cal. yr BP. [ABSTRACT FROM AUTHOR]

The pollen and sedimentary record from a coastal backdune swamp on the island of Mua, Torres Strait, Australia, is presented. A 4.55 m core collected from the swamp centre provides a record of vegetation and landscape change spanning the postglacial marine transgression to present. Prior to 6000 radiocarbon years before present (yr BP) results show mangrove vegetation encroaching on the core site, periodically displacing non-mangrove taxa until the establishment of an extensive mangrove forest between 6000 yr BP and 3000 yr BP. Within the mangrove community a transition from lower-tidal Rhizophora forest to an upper-intertidal Ceriops community is evident. This is followed by the development of the current herbaceous freshwater swamp in the late Holocene. The dryland vegetation record is dominated by sclerophyll and rainforest elements with strongest forest representation occurring around the mid Holocene before a decline in tree density and the establishment of open woodlands in the late Holocene. The data suggest vegetation change accompanied marine transgression and a humid mid-Holocene climate, before stabilization of sea levels and the initiation of dominant on-shore catchment processes, signalling drier climatic conditions and possible human activity. [ABSTRACT FROM AUTHOR]

The sedimentological and palynological study of the Gallocanta lake sediments, in the NE of Spain, has allowed the Holocene environmental evolution of this lacustrine basin to be established, and several changes in the hydrological balance to be interpreted. The chronology of the sequence is based on new radiocarbon datings and 210Pb radiometric techniques. Ten facies have been characterized, which have been grouped into five sedimentary units: two (Units A and B) are interpreted as deposited in alluvial areas, and three (Units C, D and E) in lacustrine environments. Moreover five pollen zones have been established for this succession. From the stratigraphic correlation of the cores extracted in this lake, three stages in the basin evolution have been interpreted. Stage 1 was characterized by a broad development of alluvial fans during the Fullglacial or Lateglacial times. The sediments of this stage are lacking in pollen as they were exposed for most of the time. Stage 2 started around 10 100 yr BP and is characterized by the establishment of a brackish lake linked to a decrease in alluvial supplies and a more positive water balance. The maximum lake level would have been reached around 8010 yr BP coinciding with the relatively moist period of the beginning of the Holocene recorded in some Spanish lakes, although this dating would not match that of other areas of the Iberian Peninsula, in which the maximum lake levels have been recorded around 6000 yr BP. A sharp decrease in the lacustrine level has been registered at 3405 yr BP, which may be correlated to a change to more arid conditions. Nevertheless, the lake level recovered later. Stage 3 was linked to the development of an ephemeral shallow lake. An age of AD 1840 yr has been calculated for this palaeogeographical change. The data obtained suggest that the main vegetation changes during stage 2 were more related to climate variability, whereas during stage 3 the anthropogenic impact became more significant. [ABSTRACT FROM AUTHOR]

A late-Holocene swamp sediment record is presented from the Dongnimdong archaeological site in SW Korea. Pollen analysis, geochemical analyses and radiocarbon dating have been used to reconstruct the vegetation and climatic changes. According to the pollen records, temperate deciduous broadleaved trees combined with herbs predominated in the study area ecology. Reduction of deciduous broadleaved trees with the spread of herbaceous taxa found in the middle part (c. 3300–2600 yr BP) indicates climatic change toward cooler and drier conditions. Significant increase in sand content and concomitant decrease in TOC content may suggest the occurrence of a period of drought. Vegetation changes recorded in the pollen sequence indicate the destruction of lowland deciduous forests and an accompanied expansion of grasses resulting from the climate changes. However, the increase of cultivation-accompanied herbs and excavated wooden tools for agriculture suggest the significant anthropogenic influence on the vegetation changes. [ABSTRACT FROM AUTHOR]

Surface pollen deposition at five sites (Kichikol, Karakol, Nishneye and Verkhneye Ozero, and Bakaly) in four different forest types (Juniperus, Picea, Juglans and mixed forests) in Kyrgyzstan have been investigated to assess the relationship between modern vegetation and pollen composition in order to calibrate the pollen representation. Vegetation surveys with an estimation of the tree-crown cover (%) were made in 10m X 10 m plots to relate the vegetation to surface pollen of moss polsters. Correlation calculations show a close relationship between vegetation (tree-crown cover) and pollen for the Juniperus site (eg, r² = 0.76 between crown cover and arboreal pollen, AP) and the Picea site (r² = 0.85), whereas the linkage is weaker at the Juglans site (r² = 0.35) and in mixed forests (r² = 0.32). The results of the surface samples of moss polsters are compared and discussed with surface samples of lake sediments that were taken at the same locations. We use vegetational maps from around the lakes to discuss the link between vegetation and pollen at extra-local scales (800 m around the sites). These comparisons show that AP underestimates the effective tree cover around all sites, with in extreme cases densely forested areas corresponding to AP values as low as <60; 30%. We explain this finding by the prevalent background pollen load that derives from the dry lowland and slope steppes (Artemisia, Chenopodiaceae, Poaceae). Our investigation may improve the reconstruction of Quaternary vegetation and climate history of these forest belts in Kyrgyzstan (Central Asia) on the basis of fossil pollen assemblages from mire and lake sediments. It provides new insights into the pollen reflection of forest isles (eg, on humid slopes or mountain tops) that are surrounded by continental steppes; a vegetational situation that may be used as an analogue for the conditions during the full glacial in Eurasia and Northern America. [ABSTRACT FROM AUTHOR]

Vegetation strongly influences exchanges of energy and moisture between land and atmosphere through (1) the vegetation's response to incoming radiation and its emission of longwave radiation (2) the vegetation's physical presence, and (3) the plant's transpiration. These processes affect the diurnal temperature range, processes in the atmospheric boundary layer, cloud cover, rainfall, differential heating, and atmospheric circulations. This paper overviews how vegetation interacts with surface energy and moisture budgets and reviews both observational and modelling studies that examine how vegetation affects weather and climate on the mesoscale (ie, phenomena 10s to 100s of kilometres in horizontal size). [ABSTRACT FROM AUTHOR]

Pollen analyses of a peat profile collected from Butterburn Flow, northern England have been used to reconstruct vegetation and land-use change from the late Neolithic (c. 3230 cal. BC) to the present day. ‘Wiggle-matching’ of 42 AMS 14C dates has enabled a precise (decadal scale) chronology to be established, and the results are interpreted within the context of previous studies of vegetation change in the area. Three late Neolithic-Bronze Age woodland clearance phases occurred, with the first beginning c. 2290 cal. BC. Cleared areas were utilized for pastoral and limited arable agriculture. Late Iron Age clearance and agricultural intensification began at Butterburn Flow c. 300 cal. BC; the peak period of clearance c. 90 cal. BC-AD 50 cal. was comparable in intensity with that in the fourteenth century AD. Farmland in the area was abandoned during the period c. AD 90ȁ3450 cal., contemporaneous with the Roman occupation of the region; Following Roman withdrawal, a resurgence of agriculture occurred. The timing of later periods of agricultural decline relate to climatic deterioration, political instability and disease in the region. [ABSTRACT FROM AUTHOR]

This study aimed to assess the time needed by rats, which had not been previously transported, to acclimatize to a new environment after 5 h of van transport, using physiological parameters as measures of acclimatization. Animal shipping boxes and transport van conditions were standardized to minimize stress factors that could be associated with transport. Heart rate (HR), body temperature and activity levels were measured in the rats before and after transport using previously implanted radio-telemetry transmitters. Body weight was also recorded. All parameters were changed significantly except for body temperature. Results suggest that rats take three days to acclimatize to a new environment, as measured by the physiological parameters of body weight, HR and activity. [ABSTRACT FROM AUTHOR]

Quantitative reconstruction of past vegetation is one of the primary goals in Quaternary palynology and palaeoecology but still remains difficult. This paper proposes a model, REVEALS, that estimates regional vegetation composition using pollen from ‘large lakes’ that have small site-to-site variations of pollen assemblages even if vegetation is highly heterogeneous. Once these data have been used to quantify regional vegetation composition within 104-105 km², background pollen, one of the parameters crucial for vegetation reconstruction, can be estimated for smaller-sized sites, and incorporated into the Landscape Reconstruction Algorithm (LRA), a multistep framework for quantitative reconstruction of vegetation in smaller areas (≤/104 ha). Simulations using the POLLSCAPE modelling show that REVEALS can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions. If pollen assemblages from lakes that are much smaller than ‘large lakes’ are used, estimates of regional vegetation at individual sites could be significantly different from the expected values, and their site-to-site variation could be large. However, when pollen data from multiple lakes ≥100-500 ha in size are available, REVEALS can provide accurate estimates of the regional vegetation with relatively small standard errors. Quantitative reconstruction of regional landscape and vegetation change will be critical for testing some of the controversial hypotheses and concepts in global change and conservation research, such as the impacts of agricultural activities on global climate over the last 8000 years and the open-woodland hypothesis in northern Europe in the early Holocene. [ABSTRACT FROM AUTHOR]

This paper describes the LOVE (LOcal Vegetation Estimates) model for estimating local vegetation composition within the relevant source area of pollen. This model quantifies and then subtracts background pollen (ie, pollen coming from beyond the relevant source area) in order to arrive at a quantitative reconstruction of local vegetation. Parameters required for LOVE applications are pollen counts from target sites, the relevant source area of pollen of these sites, pollen productivity estimates and regional vegetation composition within 104-105 km². Regional vegetation composition is obtained using fossil pollen from large sites (≥/10² ha) with the REVEALS (Regional Estimates of VEgetation Abundance from Large Sites) model, the first step of the Landscape Reconstruction Algorithm (LRA) specifically designed for LOVE applications. POLLSCAPE simulations demonstrate that (1) regional vegetation composition can be used to predict background pollen at and beyond the relevant source area of pollen for given-sized basins, (2) LOVE with the LRA framework provides a robust and accurate estimate of local vegetation composition much better than vegetation reconstruction using pollen percentages alone and (3) although the relevant source area of pollen is difficult to estimate particularly in past landscapes, a proposed method using backward modelling of LOVE is effective to estimate the relevant source area in landscapes of unknown vegetation patchiness and heterogeneity. Thus, the LRA will also be useful to estimate indirectly changes in spatial structure of past vegetation and landscape caused by natural and anthropogenic forcing. [ABSTRACT FROM AUTHOR]

A palaeoecological study was performed in the northern Scandinavian mountain range in Sweden. The aim was to study vegetation changes and shifts in forest limit altitudes during the last 5000 years in a tree-less archaeological site (Adamvalta) situated below the regional forest limit, and in a forested reference area with similar geological features but without archaeological evidence of human presence (Ajdevaratj). The suitability of uncritically using forest limit changes as indicators of climate change is also discussed. The study included analyses of pollen, pollen accumulation rates (PAR), macrofossils and loss-on-ignition. The results indicate vegetation changes in both areas plausibly caused by climate c. 3800 BP and c. 500–400 BP. However, at Adamvalta, settlements were established c. 1300–750 BP, close to the mountain birch (Betula pubescens ssp. czerepanovi) forest limit. About 800 BP, the birch forest cover at Adamvalta decreased and the vegetation developed into an alpine heath, as a result of human-induced deforestation. The following ‘Little Ice Age’, in combination with human impact from the sixteenth century onwards, prevented forest recovery, and the site remains treeless. Such vegetation changes were not recorded at Adjevaratj. It is deduced that the present position of the forest limit at Adamvalta is governed by a combination of factors where previous human impact and climate have been the major driving forces determining the long-term vegetation development. Hence, a thorough knowledge of the site history is important when forest limits are used as a proxy for climate change. [ABSTRACT FROM AUTHOR]

We present the first step to quantitatively reconstruct vegetation cover in central Europe. Modern vegetation and pollen deposition were compared for 20 small to medium sized lakes and their catchments on the Swiss Plateau, a relatively flat region between the Jura Mountains and the Alps. To correct for the pollen dispersal bias in pollen assemblages, vegetation abundance was distance-weighted using three different approaches. The Relevant Source Area of Pollen (RSAP) and pollen productivity of 13 plant taxa were estimated using three different submodels of the Extended R-Value model (ERV-model). RSAP was 800 m regardless of the applied distance-weighting or ERV submodel. Pollen Productivity Estimates (PPE) varied from 10 to <0.1 among pollen taxa and differed slightly between the models. Relative to grasses most trees were higher pollen producers and some were equal producers, whereas the herb taxa showed lower PPE. Generally, PPE from lowland Switzerland differ from those found in other European regions. Sampling strategies of vegetation and pollen samples are a likely cause for this variation. However, pollen productivity is also influenced by regionally different factors, such as climate, vegetation structure, geology and soil types. In addition, differences at genus or species level may occur between areas. Our comparison between the different regions in Europe shows that PPE of one region may not be directly applicable to other regions. [ABSTRACT FROM AUTHOR]

Mid-late Holocene pollen evidence from the Ispani-II Sphagnum bog in lowland Western Georgia shows that 4500 years ago Castanea (chestnut)-dominated woods rapidly declined to be replaced by alder swamps and, later, during the first millennium bc, by open, marshy landscapes in which fire played a prominent part. Around 1900 years ago, Sphagnum blanket bog encroached on the marshes and dense Fagus-Carpinus (beech-hornbeam) forest enveloped the surrounding land. This vegetation remained until the mid-twentieth century, when forests were clear-felled and marshes were drained for large-scale, mechanized agriculture. Previous studies have emphasized climate's governing role in setting the course of Holocene vegetation development in lowland Western Georgia, but our results provide little support for this hypothesis. To a much greater degree, episodes of coastal subsidence, sea-level rise and human impact have shaped the vegetation history of coastal Western Caucasus. [ABSTRACT FROM AUTHOR]

Potential impacts of projected climate change on biodiversity are often assessed using single-species bioclimatic 'envelope' models. Such models are a special case of species distribution models in which the current geographical distribution of species is related to climatic variables so to enable projections of distributions under future climate change scenarios. This work reviews a number of critical methodological issues that may lead to uncertainty in predictions from bioclimatic modelling. Particular attention is paid to recent developments of bioclimatic modeling that address some of these issues as well as to the topics where more progress needs to be made. Developing and applying bioclimatic models in a informative way requires good understanding of a wide range of methodologies, including the choice of modelling technique, model validation, collinearity, autocorrelation, biased sampling of explanatory variables, scaling and impacts of non-climatic factors. A key challenge for future research is integrating factors such as land cover, direct CO2 effects, biotic interactions and dispersal mechanisms into species-climate models. We conclude that, although bioclimatic envelope models have a number of important advantages, they need to be applied only when users of models have a thorough understanding of their limitations and uncertainties. [ABSTRACT FROM AUTHOR]

The use of pollen records to document vegetation responses to climatic change in mountains relies on the ability of pollen assemblages to differentiate among elevationally stratified vegetation zones. Comparisons among modern pollen assemblages within mountainous areas provide a basis for assessing this potential. We examined relationships between pollen assemblages, forest vegetation and climate at 65 small lake sites distributed across five forest zones on the Olympic Peninsula, Washington. Sample sites spanned nearly the full range of climatic gradients on the Peninsula, c. 900–6000 mm annual precipitation and c. 17–8°C July mean temperature (from 9 to 1981 m a.s.l.). The pollen percentages of most arboreal taxa showed a strong relationship with elevation, especially for taxa with poor dispersal potential (Abies and Picea) or high elevation ranges (Tsuga mertensiana and Alnus sinuata). Tsuga heterophylla was the only pollen taxon abundant across all forest zones. Both detrended correspondence analysis (DCA) and linear discriminant analysis (DA) arranged pollen assemblages along temperature and precipitation gradients approximating the actual distribution of vegetation along these gradients. DA classified 90% of the sites into their correct forest zones, but was very sensitive to sample size, suggesting that caution should be exercised when using DA for classifying fossil pollen assemblages. Pairwise comparisons using the squared-chord-distance metric (SCD) showed that the SCD threshold that best distinguishes neighbouring forest zones is affected by the number of samples in each forest zone and by the patchiness of species distributions within each zone, suggesting that SCD is also sensitive to sample size and that thresholds used with the modern analogue technique must be calibrated for each vegetation zone. This study indicates that pollen assemblages on the Olympic Peninsula record local forest zones despite steep environmental gradients and the close proximity of neighbouring forest zones. [ABSTRACT FROM AUTHOR]

Changes in Faroese land surfaces during the late Holocene reflect intimate interactions between cultural and environmental development. Analyses of fossil wood, pollen and plant macrofossils indicate that the present open landscape replaced shrubby vegetation that was present from c. 6000 BC up to c. AD 660. Conditions altered during the late Holocene, with loss of woody vegetation and increasing erosion: trends that were initiated prior to human settlement. AMS dating of sub-fossil Betula, Salix and Juniperus found buried in peat profiles from the islands of Suðuroy, Sandoy, Eysturoy, Vágar and Streymoy, revealed that the islands had at least partial woody vegetation cover up to the time of continuous settlement. The settlement horizon, identified in a lacustrine sequence on the island of Eysturoy, dated to c. AD 570. It comprised pollen evidence for the cultivation of Hordeum, cultural macrofossil assemblages, charcoal fragments, diatom assemblage changes indicating lake nutrient enrichment and physical measurements showing increased sedimentation rates. The pollen record showed that heathland development was initiated prior to anthropogenic impact. The ecosystem impacts of settlement were therefore superimposed on landscape changes that began around AD 250. The earlier changes were most likely forced by increased storminess and declining atmospheric temperatures. [ABSTRACT FROM AUTHOR]

Two peatlands, a fen and a bogin southern Finland, were studied for peat and carbon accumulation rates, chemical and physical properties of the peat profile, and past vegetation, to assess what stage of succession these peatlands were at the time of human impacts, drainage and restoration. Paludification started at both sites soon after the glacial retreat around 9000 radiocarbon years BP. Peat accumulated at the fen site at an average rate of 0.28 mm yr-1 (range 0.16-0.58 mm yr-1 ) duringdevelopment. The peat was composed mostly of Carex with remains of Pinus sylvestris and Betula spp. The bogsite had an average accumulation rate of 0.47 mm yr-1 (range 0.25-1.19 mm yr-1), and a minerotrophic sedge stage of about 2000 years in its early development, after which the peat was composed mostly of Sphagna. The long-term rates of carbon accumulation (LORCA) varied from 6.6 to 15.3 g m-2 yr-1 (average 11.1 g m-2 yr-1) for the fen and from 6.1 to 21.1 g m-2 yr-1 (average 13.2 g m-2 yr-1) for the bog. The main trend in peat chemistry of both mires was the change from higher to lower nutrient levels with an increased acidity towards the surface peat. The main changes in peat chemistry occurred between 4600 and 4200 BP, simultaneously with the spread of Picea abies in the area. This period was preceded by a large-scale climatic change at the boundary between Atlantic and Subboreal chronozones. Drainage during the twentieth century caused compaction in the uppermost peat of the fen, whereas evidence of drainage was hardly noticeable in the bogstratigraphy. [ABSTRACT FROM AUTHOR]

Natural middle- and late-Holocene environmental development of Kunashiri Island reflects global climatic changes and the migration of warm and cold currents. Dry and cool climate changed to warm and moist about 7000–6500 BP, later than on Hokkaido Island. At this time Kuroshio Current system became more active. On Kunashir Island birch assemblages were replaced by cool-temperate broadleaf forests in the south and mixed coniferous/broadleaf forests in the north. The highest sea-level position reached 2.5–3 m above PSL about 6500–6300 BP. Cooling about 4700–4500 BP island vegetation weakly changed that connected with warm current influence. Major regression at this period led to formation of extensive coastal dunefields. The warming at the beginning of the late Holocene was almost similar to the Holocene Optimum. Two minor transgressions are recorded about 4010–3400 and 2950–2620 BP. Active entrance of detrital material to the coastal zone resulted in growth of accumulative landforms. Vegetation changes and climatic deterioration took place in the second half of the late Holocene. Coniferous and mixed coniferous/broadleaf forests shifted south-ward and occupied a large part of the island. During cooling at 1700–1300 BP the isthmus area increased, coastal wetlands with lakes and coastal dunes were formed, and grassland and swamp landscapes developed. Late-Holocene warming was not intensive. Active aeolian accumulation took place during the ‘Little Ice Age’ cooling and regression. [ABSTRACT FROM AUTHOR]