Persistence of Artemisia steppe in the Tangra Yumco Basin,west-central Tibet,China: despite or in consequence of Holocene lake-level changes?

The closed Tangra Yumco Basin underwent the strongest Quaternary lake-level changes so far recorded on the Tibetan Plateau. It was hitherto unknown what effect this had on local Holocene vegetation development. A 3.6-m sediment core from a recessional lake terrace at 4,700 m a.s.l., 160 m above the present lake level of Tangra Yumco, was studied to reconstruct Holocene flooding phases (sedimentology and ostracod analyses), vegetation dynamics and human influence (palynology, charcoal and coprophilous fungi analyses). Peat at the base of the profile proves lake level was below 4,700 m a.s.l. during the Pleistocene/Holocene transition. A deep-lake phase started after 11 cal ka BP, but the ostracod record indicates the level was not higher than ~4,720 m a.s.l. (180 m above present) and decreased gradually after the early Holocene maximum. Additional sediment ages from the basin suggest recession of Tangra Yumco from the coring site after 2.6 cal ka BP, with a shallow local lake persisting at the site until ~1 cal ka BP. The final peat formation indicates drier conditions thereafter. Persistence of Artemisia steppe during the Holocene lake high-stand resembles palynological records from west Tibet that indicate early Holocene aridity, in spite of high lake levels that may have resulted from meltwater input. Yet pollen assemblages indicate humidity closer to that of present potential forest areas near Lhasa, with 500–600 mm annual precipitation. Thus, the early mid-Holocene humidity was sufficient to sustain at least juniper forest, but Artemisia dominance persisted as a consequence of a combination of environmental disturbances such as (1) strong early Holocene climate fluctuations, (2) inundation of habitats suitable for forest, (3) extensive water surfaces that served as barriers to terrestrial diaspore transport from refuge areas, (4) strong erosion that denuded the non-flooded upper slopes and (5) increasing human influence since the late glacial.     

Quantification of Holocene lake-level changes in Finnish Lapland using a cladocera – lake depth transfer model

During recent years, numerous studies dealing with Holocene lake level fluctuations have been conducted in Finnish Lapland. However, no quantification of lake level variations exists to date. Here, we applied a recently developed modern cladocera – lake depth transfer model to subfossil cladocerans analysed from three small and shallow (< 6 m) kettle-hole lakes in northwestern Finnish Lapland to provide estimates of the amplitudes of long-term lake-level changes in the region. The quantitative inferences were compared to pollen, charcoal and geochemical records from one of the study sites. The lake levels were inferred to be high during the early Holocene; they faced marked reduction up to 4–6 m in the mid-Holocene (≈7000–4000 cal yr BP), and rose again during the latter part of the Holocene. There is some indication of lowered lake levels around 1500 cal yr BP, but interpretation of such small-scale changes is hazardous due to large prediction errors in the initial cladoceran model. The overall pattern of the Holocene lake level variation generally followed the regional changes in climate humidity as reconstructed in previous studies by means of other sedimentary proxy indicators, such as pollen and oxygen isotopic compositions. We postulate that changes in winter precipitation may have had a greater influence on lake-levels than variations in summer precipitation or evaporation.     

Holocene vegetation history of Bundjalung National Park and Bungawalbin Creek,north‐eastern New South Wales

Few studies have been conducted into the environmental history of the North Coast region of New South Wales (NSW). To address this, two sedimentary sequences located in the coastal Bundjalung National Park and at Bungawalbin Creek, just north of the Park (both near Evans Head, NSW) have been investigated. Palynological and geochemical analyses were used to reconstruct the history of the sites. Fossil pollen evidence representing much of the Holocene period — basal radiocarbon dates of 8700 ± 60 years BP and 6600 ± 60 years BP are available from the Bundjalung National Park and Bungawalbin Creek sites, respectively — indicates a dynamic past environment, with an overall tendency towards drier conditions. This evidence is supported, in part, by charcoal analyses indicating an increase in the occurrence of fire over time. Chemical analyses of the sediments indicate that the Bungawalbin site was strongly influenced by estuarine conditions, whereas the Bundjalung National Park site was only influenced indirectly by estuarine conditions.     

The Holocene palaeolimnology of Sägistalsee and its environmental history – a synthesis

Multi-proxy palaeoecological and palaeolimnological studies of the sedimentary record of Sägistalsee, a small lake at the present-day timberline in the Swiss Alps, reveal distinct changes in its catchment vegetation in relation to Holocene climate change and human impact. Four phases of catchment vegetation type were defined based on plant macrofossil analyses: open Betula-Pinus cembra woodland, Abies alba-Pinus cembra woodland, Picea abies forest, and cultural pasture. The expansion of spruce 6300 cal. BP had a major impact on all abiotic proxies, whereas the reaction of the biotic proxies to this catchment change was lagged by several centuries. During the Bronze Age (ca. 4000 cal. BP) the spruce forest was cleared and the catchment began to be used as grazing pastures. Changes in sedimentology, geochemistry, and magnetic parameters closely reflect the changes in catchment vegetation. The catchment vegetation types explain a statistically significant amount of the variance in the chironomid, cladoceran, sedimentological, and magnetic data but not in the geochemical data. The strong catchment-lake interaction masks any biotic responses to millennium-scale climatic oscillations.     

Early Holocene shore displacement and evidence of irregular isostatic uplift northwest of Lake Vänern, western Sweden

In the 1920's the Swedish geologist Lennart von Post found evidence of irregular early Holocene isostatic uplift in the region northwest of Lake Vänern in western Sweden. von Post based his conclusions on levellings of ancient shore lines. These were indirectly dated by pollen stratigraphical investigations in basins situated at approximately the same altitudes as the shore lines. To test von Post's hypothesis, we have adopted a different methodological approach. The sediments in twelve small lake basins, within five minor areas in this region, have been investigated with respect to when they became isolated from ancient Lake Vänern. Initially all the lake thresholds were levelled. Altitudes range between 165 and 96 m above sea level. By combining the results of mineral magnetic and diatom stratigraphical analyses it has been possible to determine the level in the sediment when the basin became isolated. The ¹⁴C age of this isolation level has been inferred from AMS dates based on the NaOH-soluble fraction of bulk sediment, partly with very low organic content. Altogether, 36 radiocarbon datings have been carried out, ranging from 10080 to 8800 ¹⁴C years BP. Pollen analyses, and subsequent correspondence analysis (CA) of all pollen spectra, were carried out around the isolation level in each basin as a complement to the AMS datings.If the region had been subject to irregular isostatic uplift, lakes at the same altitude in the five areas should have been isolated at different times. The AMS determined isolation ages, corrected according to CA of the pollen stratigraphy and compensated for the relatively higher rebound of the northerly situated sites support von Post's conclusion, from the beginning of this century, that the region northwest of Lake Vänern has been subjected to irregular isostatic uplift.     

ICT development from the perspective of connectivity and inclusion – the operation of a local digital agenda in Sweden

ABSTRACT

The aim of the article is to determine what a local Digital Agenda (DA) implies for ICT development at the local level and how such a policy can be realised in practice. The topic is discussed in relation to the EU and Swedish Digital Agendas, which have motivated the definition of a local DA for the examined Swedish municipality of Linköping. An analytical model is used both to examine the balance of supply-side and demand-side policies of the local DA, and in an attempt to determine what a local DA implies for local ICT development. The empirical material shows that local policy focused on supply-side strategies towards households and businesses, while demand-side policy was present to a greater extent in the management of the municipality’s own operations. The local authority has provided a major expansion in broadband infrastructure to rural areas of the municipality. This complies with mandates from local authorities to manage local infrastructure development and services to the local population. The authors conclude that the policy implications of the results suggest that although operations through the local DA are substantial, complementary measures to support increasing demands across households and businesses are important when dealing with challenges of uneven access and underutilisation of the large investments for ICT infrastructure.     

Geochemical responses to paleoclimatic changes in southern Sweden since the late glacial: the Hässeldala Port lake sediment record

There is a relatively good understanding of the paleoenvironmental changes that have occurred in southern Sweden since the Late Glacial. A main exception, however, is the sedimentary response of lacustrine systems during this period of rapid climate shifts. To address this, high-resolution X-ray fluorescence core scanning, Total Organic Carbon (TOC), C/N and δ¹³C analyses were made on a core from Hässeldala Port, a paleolake in the region. Site-specific geochemical analyses documented variations in silicate inputs (Zr/Ti, Si/Ti, K/Ti and K/Rb), productivity (TOC, Ca/Ti and Sr/Ti), as well as redox conditions in the sediment (δ¹³C, Mn/Ti and Fe/Ti), which were then linked to the regional climatic framework. During the Bølling/Older Dryas sediment accumulation was at its highest, particularly prior to colonization by terrestrial vegetation, and hydrological transport dominated. No clear signal of the Older Dryas was detected in the elemental chemistry. The Allerød was a period of relatively constant sediment accumulation, with the exception of during the Gerzensee oscillation when rates increased. There is evidence for increased within-lake and -catchment productivity and a change in silicate source during parts of the Allerød. As opposed to other records from the region, constant sediment accumulation rates were found during the Younger Dryas. Other proxies also suggest that this was a rather static period at Hässeldala Port. A gradual change in productivity and hydrological activity was observed from 12,000 cal year BP. The Preboreal section is rather short but the geochemical response was similar to that seen during other periods with milder climate conditions. The geochemical record archived in the sediments at Hässeldala Port was found to be the integrated result of physical erosion, landscape and soil development, vegetation changes, basin hydrology and moisture and temperature variations and it fills an important information gap in our understanding of the geochemical response of lake sediments to past climate change.     

Periglacial nivation cirques and local glaciations in the rock canyons of Söderåsen,Scania, Sweden. A discussion and new interpretation

Rapp, Anders: Periglacial nivation cirques and local glaciations in the rock canyons of Söderåsen, Scania, Sweden. A discussion and new interpretation. Geografisk Tidsskrift 82: 95–99, Copenhagen, October 15, 1982.

Present opinions about the genesis of the rock canyons OdensjOn, Skäralid and Klöva Hallar of Söderåsen, Sweden are reviewed, and a new theory is presented. It is proposed, that during periglacial tundra periods large amounts of drifting snow collected in valleys of north-south directions. Small glaciers were created, which caused local overdeepening and removal of loose material. These processes were active in tundra periods before and after the main Quaternary glaciations.

SUMMARY

Odensjön, Skäralid and Klöva Hallar are three valleys of canyon type, deeply cut (60–100 m) into the horst block of Söderåsen, of fractured Precambrian gneiss rock. It has been shown by other authors that the cold periods after the Weichselian deglaciation were characterized by permafrost and ice wedges on sandy plains in south Sweden. Strong winds caused widespread wind-polishing of stones and bedrock, predominantly from easterly and westerly directions. Based on this evidence, the author presents the theory that large deposits of wind-blown snow were trapped in the canyon valleys of Söderåsen, except for the valleys of east-west directions. The snow was metamorphosed to firn and local, small glaciers, which filled the valleys. The rims of the canyon valleys have in many cases well developed nivation hollows, either steep nivation funnels or gently sloping, semicircular nivation cirques. Odensjøn is a closed, semicircular rock basin, which has been much discussed by scientists earlier, and which seems to fit the theory of creation by nivation from mainly west, but also east, and a local cirque glacier flow northwards causing the overdeepening and removal of loose material. The three valleys mentioned were problably widened and deepened into a series of nivation basins in tundra periods before and after each major continental glaciation. The nivation hollows and the deep canyon valleys were not destroyed by glacial erosion during the Weichselian and earlier Quaternary major ice advances, because the valleys were filled with densely packed snow and ice from snow drifting before the main glacier front moved over them from NE directions. The theory will be further checked by a team of scientists from the Department of Physical Geography in Lund. A comparison is made with cirque forms in present-day mountain tundra conditions in the area of Kärkevagge in northern Lappland, investigated by the author during the 1950's and later.     

Environmental changes in northern New Zealand since the Middle Holocene inferred from stable isotope records (δ15N, δ13C) of Lake Pupuke

Maar lakes in the Auckland Volcanic Field are important high-resolution archives of Holocene environmental change in the Southern Hemisphere mid-latitudes. Stable carbon and nitrogen isotope analyses were applied on bulk organic matter and the green alga Botryococcus from a sediment core from Lake Pupuke (Auckland, North Island, New Zealand) spanning the period since 7,165?cal.?year BP. The origin of organic matter was established using total-organic?Ccarbon-to-nitrogen ratios (TOC/TN) as well as organic carbon (??¹³C_OM) and nitrogen (??¹⁵N) isotope composition of potential modern sources. This approach demonstrated that the contribution of allochthonous organic matter to the lake sediment was negligible for most of the record. The sedimentary TOC/TN ratios that are higher than Redfield ratio (i.e. >7) are attributed to N-limiting conditions throughout the record. Variations of nitrogen and carbon isotopes during the last 7,165?years are interpreted as changes in the dominant processes in the lake. While epilimnetic primary productivity controlled isotope composition before 6,600?cal.?year BP, microbial processes, especially denitrification and methane oxidation, caused overall shifts of the ??¹⁵N and ??¹³C values since the Mid-Holocene. Comparisons with climate reconstructions from the Northern Island suggest that changes in the wind-induced lake overturn and a shift to more pronounced seasonality were the most likely causes for lake-internal changes since 6,600?cal.?year BP.     

Vegetation and sedimentation in the Lake Edward Basin, Uganda–Congo during the late Pleistocene and early Holocene

New palynological and sedimentological data obtained from the basal 3 m of core E96-2P from Lake Edward, Uganda–Congo record conditions wetter than present in the Edward basin from 11 000 to 6700 yr BP, in phase with other climate and vegetation records of northern hemispheric East Africa. Dominant pollen taxa include Celtis spp., Alchornea spp., Olea spp., and Moraceae indicating a moist semi-deciduous tropical forest. More xeric indicators such as Amaranthaceae and Asteraceae together with Poaceae comprise less than 5% of the pollen sum throughout this interval as compared with between 44 and 50% during a lake lowstand at 2000 cal yr BP and at the core top (near modern). The differences between these two assemblages suggest a 25 to 60% increase in annual precipitation during the early- to mid-Holocene as compared to modern (1500–2000 vs. 1200 mm/yr today). Early Holocene sediments in E96-2P are composed of laminated diatom oozes with moderately high total sulfur concentrations (2.8–4.7%) and no authigenic calcite, also indicative of conditions wetter than present. Between 9000 and 6700 yr BP, palynological and sedimentary proxies indicate sub-millennial-scale events related to changes in riverine discharge and runoff in the Edward basin. We attribute the variability in runoff, and hence precipitation, to Holocene variability in Indian or Atlantic Ocean SSTs or to shifts in the relative contribution of Indian and Atlantic moisture sources to the western Rift of equatorial Africa.     

Post-glacial rock weathering processes on a roche moutonn@e in the Riksgränsen area (68°N), northern Norway

Weathering processes responsible for landscape denudation in Arctic environments are poorly understood. Traditionally, gelifraction has been widely invoked as the dominant weathering process, but empirical support for this is frequently lacking. In Norwegian Lapland, post-glacial weathering has been recently attributed to predominantly biophysical processes, based on field measurements of landscape lowering undertaken by André (1995). The study reported here examined bedrock samples from one of André's sites for mineralogical and chemical transformations since post-glacial exposure. Backscatter scanning electron microscopy reveals extensive mineral grain dissolution and accompanying development of rock porosity. Wavelength dispersive spectroscopy shows these mineral alterations to be the result of the loss of major chemical constituents including Ca, Mg, K, Si, and Al. Chemical weathering is clearly a component of post-glacial landscape denudation in Norwegian Lapland, in addition to the important role of biophysical processes identified by André (1995). Cosmogenic dating of the sampled bedrock surface confirms that much of this weathering has occurred in the last 10,000 years.     

Holocene environmental history and climate of Råtåsjøen,a low-alpine lake in south-central Norway

The Holocene environmental history and climate are reconstructed for Råtåsjøen, a low-alpine lake in south-central Norway. The reconstructions are based on chironomids, diatoms, pollen, plant macrofossils, and sediment characteristics. From plant macrofossil evidence, birch trees (Betula pubescens) immigrated ca. 10,000 cal BP. The chironomid-inferred mean July air temperature was high, but may be unreliable during the early stages of the lakes history due to the high abundance of Chironomus anthracinus type, a taxon that may include several species. From ca. 9000 cal BP the inferred mean July temperature was lower (ca. 9 °C). Temperatures increased towards 8000 cal BP and pine (Pinus sylvestris) reached its upper limit near the lake. July temperature may have become a significant factor controlling long-term pH in the lake, starting shortly after 8000 cal BP. High pH values were associated with periods of warm summers and lower pH values occurred during periods of colder summers. Alkalinity processes within the lake and/or the catchment are possible factors controlling this relationship. A temperature decline at ca. 5400 cal BP separated two 10.6 °C temperature maxima around 6400 and 4500 cal BP. The 1.5 °C decline in July air temperatures from ca. 4400 cal BP was paralleled by a decrease of pH from 7.2 to 6.8. Following the temperature drop, first pine and then birch trees declined and disappeared from the catchment and organic accumulation in the lake increased. The increased organic accumulation rate had a positive effect on diatom production. At ca. 2700 cal BP the temperature reached a minimum (ca. 9.2 °C) and correspondingly a second pH minimum was reached. Temperature decreased again slightly at ca. 400 cal BP during the Little Ice Age, before increasing by about 0.5 °C towards the present. Percentage organic carbon as estimated by loss-on-ignition appears to be better correlated with chironomid-inferred July temperatures than organic accumulation rates, at least for the last 9000 years. Accumulation rates of organic sediments are more coupled with catchment-related processes, such as erosion and major changes in vegetation, than is percentage organic carbon.     

Midge-inferred temperature reconstructions and vegetation change over the last ~15,000?years from Trout Lake, northern Yukon Territory, eastern Beringia

Two cores from Trout Lake, northern Yukon, yielded quantitative estimates of summer air temperatures using fossil midge larvae. Warming began around 14,400?cal?yr BP, with inferred mean July air temperatures reaching values warmer than present by 12,800?cal?yr BP. A 1?°C cooling from 12,200 to 11,200?cal?yr BP closely corresponds with the Younger Dryas chronozone. A broad temperature maximum occurred between 10,800 and 9,800?cal?yr BP, with mean July air temperature about 2.2?°C warmer than present. This represents an early Holocene thermal maximum and coincides with increased organic content of the sediment. Both the shallow- and deep-water cores show similar temperature trends for their overlapping periods. The inferred rise in mean July air temperature at 14,200?cal?yr BP coincides with a shift in vegetation from an herb- to shrub-dominated landscape. In contrast, the increase in Alnus pollen at 6,400?cal?yr BP does not coincide with a change in temperature, but may be a response to a rise in precipitation.     

Aquatic macrophyte vegetation development in Kråkenes Lake, western Norway, during the late-glacial and early-Holocene

Macrofossil analyses were carried out on the late-glacial and early-Holocene sediments of the radiocarbon-dated master core at Kråkenes Lake, western Norway, to investigate the aquatic vegetation changes. Ranunculus sect. Batrachium and Nitella were the earliest pioneers after deglaciation ca. 12,300 ¹⁴C yr BP. The Allerød vegetational succession was very slow during ca. 1000 ¹⁴C yrs in a cool climate and conditions that were similar to those above tree-line in Norway today. The rapid cooling at the start of the Younger Dryas stadial caused extensive disturbance, and with the development of an active cirque glacier in the catchment, plants and animals were almost exterminated from the lake by inflow of permanently cold and turbid water. Rising temperatures caused the glacier to melt at the end of the Younger Dryas. The biotic response to the rapid warming was immediate, with pioneer Ranunculus sect. Batrachium and Nitella expanding within 1-3 decades, closely followed by other elodeids. The lake witnessed a remarkable isoetid succession, with phases dominated by Limosella aquatica, Subularia aquatica, Elatine hydropiper, Isoetes echinospora, and, later, I. lacustris. About 800 yrs into the Holocene most of the macrophytes declined. The short-lived isoetids became extinct, but other taxa probably survived vegetatively. The reasons for this decline are unknown, but are probably related to nutrient depletion in combination with other factors. About 550 yrs later, I. lacustris and Nymphaea colonised, and a stable flora and vegetation developed. This study illustrates the large and rapid changes that occurred over the first 1400 yrs of the Holocene in the macrophyte flora and vegetation in Kråkenes Lake before stability was attained, pointing to the value of a palaeoecological study in tracing aquatic successions over time, and highlighting our lack of knowledge of the underlying ecological factors responsible for such rapid and marked changes.     

Many a little makes a mickle: Cumulative land cover changes and traditional land use in the Kyrö reindeer herding district,northern Finland

Traditional land use systems are threatened by land use intensification and resulting land cover transitions in northern areas. This article examines cumulative land cover changes and their impacts on reindeer grazing grounds in the Kyrö reindeer herding district in northern Finland. Land cover transitions were studied using Landsat TM and OLI images and topographic maps. The results showed that the herding district has experienced notable land cover changes during the past decades, and most of these changes were directly related to forestry. The proportion of continuous coniferous forests of the total forest cover declined from 92% to 78% between 1987 and 2013. Approximately one third of the forests outside current conservation areas were disturbed by forest management by 2013, and remaining forests were notably more fragmented than forests within conservation areas. The extent of the road and path networks expanded considerably between 1960s and 2010 as a result of increasing logging and tourism. Accumulation of disturbances gradually results in loss of key resources and declined quality of the landscape mosaic from the reindeer herding perspective, which can pose a serious threat to long-term sustainability of the livelihood. Rapid land cover changes in non-protected areas highlight an increasingly important role of conservation areas in maintaining resources for reindeer husbandry in the face of intensifying land use. Sustainable management of resources outside conservation areas requires careful participatory planning and efficient cumulative impact assessment of different land use activities.     

Late-glacial and early Holocene lake sediments,ground-water formation and climate in the Atacama Altiplano 22–24°S

Precipitation rates in the Atacama Altiplano 22–24°S were 400–500 mm yr^–1 during late glacial and early Holocene times as opposed to 200 mm yr^–1 today. This humid phase (Tauca phase) was likely due to strengthened tropical (monsoonal) circulation, which brought continental moisture to the Atacama Altiplano. The lake level of Laguna Lejía (23°30S, 4350 m) at that time was up to 25 m higher than it is today. Mg/Ca and Sr/Ca data from lake sediments show that, what today is a highly saline lake was a freshwater lake at that time. Seasonally-laminated calcareous sediments were deposited between 13 500 and <10 400 yr B.P. indicating the maximum of the humid phase. Climatic changes in the past are important for current groundwater resources.¹⁴C and³H data from lake-, ground- and well water suggest that modern groundwater formation (i.e. water <40 years) in the Altiplano is very limited under current arid conditions. We conclude that significant amounts of the water resources in this area originated during the time of the late-glacial and early Holocene humid climate. Tritium data from snow samples show that the moisture in the Altiplano at 22–24°S is mainly of continental origin, whereas precipitation from the westerlies hardly contributes to the water supply in this area. This precipitation pattern matches the paleodata, and we suggest that current precipitation formation may provide an analogue framework for late-glacial circulation in this area.This is the 3rd in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.     

Recent diatom assemblage changes in subarctic Lake Saanajärvi, NW Finnish Lapland, and their paleoenvironmental implications

Diatoms were analysed from a 30-cm long sediment core obtained from remote subarctic Lake Saanaärvi (69°03N, 20°52E) in order to trace possible changes in the lake. Diatom assemblages were relatively constant throughout the core, except in the top 4–5 cm (approx 1850 A.D.) where relative frequencies of Aulacoseira italica subsp. subarctica, A. lirata var. biseriata, Cyclotella comensis and C. glomerata increased markedly. No significant trends were observed in the weighted averaging (WA) reconstructed pH values. Several hypotheses, including (i) airborne pollution, (ii) climatic change, and (iii) catchment disturbances have been put forth to explain the recent changes in diatom assemblages. The diatom change coincides with a marked increase in mean annual temperature that has been documented in the area since the termination of the Little Ice Age. Our evidence favours climate change as the main causative mechanism for the observed diatom compositional changes, although other explanations cannot be ruled out.     

Assessing land-use and -cover changes in relation to geographic factors and urban planning in the metropolitan area of Concepción (Chile). Implications for biodiversity conservation

The conservation of biodiversity in Latin American metropolitan areas is threatened by the intense land-use and -cover change. Assessing the overall biodiversity changes in entire regions faces with the traditional lack of consistent biodiversity data. This work aims at contributing to this assessment through a set of major pressures to biodiversity defined from land-use and -cover changes, and evaluating their extent, distribution and correlations with geographical variables. The study was performed in the framework of the Metropolitan Urban Plan of Concepción (MUPC, Chile). Land-use and -cover maps were obtained through image classification for the years 2000 and 2010, before and after the MUPC approval, and combined in a land-use and -cover change (LUCC) map. A set of pressures to biodiversity (natural and artificial forestation, deforestation, agricultural abandonment and expansion, and urbanization) was obtained from reclassifying the LUCC map. The correlations of these pressures with a set of geographical variables were assessed using canonical ordination methods. Finally, a preliminary forecast analysis of the effects of the MUPC was performed by combining the land-use and -cover map of 2010 with the urban-extension areas of the plan.Results showed that, in only 10 years, 57% of the Concepción Metropolitan Area (CMA) was affected by land-use and -cover changes, and 48% was affected by the pressures to biodiversity. Artificial forestation and deforestation were the dominant pressures, followed by agricultural abandonment and urbanization. The geographical distribution of pressures during the 2000–2010 period also contributed to affect the conservation of biodiversity and the sustainable management of the CMA. Indeed, natural forestation occurred close to urbanization, thus threatening the ecological integrity of native forests, while artificial forestation, deforestation and agricultural abandonment took place in steeply areas thus increasing landslide risk. Despite urbanization was not the most relevant pressure in the short studied period, urban development planned in the MUPC would determine an overall increase of 60% in the built-up area of the CMA, mostly affecting brushwood and forest plantations but also native forest and wetlands. Implications of these results for the strategic environmental assessment (SEA) and the sustainable management of Latin American metropolis are finally discussed.     

Are teachers and students ready for the new middle school geography syllabus in Sweden? Traditions in geography teaching,current teacher practices,and student achievement

The article examines the relationship between selective traditions in geographical education, what middle school teachers choose to emphasise in geographical education, and student achievement. The study, conducted in Sweden, is based on observations made by students in teacher training programmes, interviews with teachers, and analyses of a test administered to middle school students. It shows that selective traditions in geographical education are strong, resulting in a focus on country-related knowledge and map-reading skills. Both teachers and students seem unclear about what other subject-specific skills geography teaching provides. Furthermore, students have difficulty achieving a high level of geographic reasoning. The authors argue that a subject-specific language in geography is important in both teaching and assessment. They stress that students need more practice in geographic reasoning, since this is required by the new curriculum and in the national test in geography for Year 6 (i.e. pupils in the age range 12–13 years). The study adds to earlier research by highlighting Swedish middle school teaching, which is a neglected field within curriculum studies, and by using a combination of methods to analyse the impact of selective traditions.