Betula Forests Research Articles

Regeneration of subalpine conifer species is inhibited by bark-stripping deer in a Betula forest

ABSTRACT Climate change is expected to alter biotic interactions governing tree species ranges. Identifying the limiting demographic processes controlling tree distribution is key to projecting future range shifts. A preference by herbivores for stripping the bark of tree species undergoing range shifts could inhibit tree range shifts. We focused on the effects of bark stripping by recently arrived sika deer (Cervus nippon) on the survival of subalpine conifers (Abies spp.) in a Betula ermanii forest in central Japan. Abies spp. which currently occur at lower elevations than B. ermanii but are predicted to expand to higher elevations with climate change, were less abundant than B. ermanii on Mt. Kita, central Japan, and were preferred by sika deer for bark stripping. The ratio of the number of stripped Abies stems to the total number of stripped stems was unrelated to elevation. Because of the lower dominance of Abies spp. at higher elevations, bark-stripping pressure on them would be stronger there. Both bark stripping by deer and competition (intra- and interspecific) contribute to the death of Abies spp. Our results suggest that bark-stripping herbivores can be an important contributing factor hampering upward range shifts of Abies spp.

The Inocybe-Conocybe workshops at Dombås 2021-2022

Some results from the Inocybe(-Conocybe) workshops at Dombås 2021-2022 are presented, with emphasis on the 2021 Inocyberesults, based on extensive ITS-DNA sequencing and phylogenetic analyses. Among the 60 Inocybe s. lat. species sequence-verified in 2021, 30 were new to Norway. Most species were found in subalpine tall-herb Betula forests and calcareous low alpine Betulanana-Salix thickets, and more than half of the species are believed to be preferentially alpine-subalpine taxa.

Floristic Homogenization and Differentiation under Deer Grazing in a Subalpine Zone in Central Japan

Changes of vegetation due to deer grazing may result in floristic homogenization or differentiation. The relationships between the changes caused by grazing are still being debated. Vascular plants and grazing by Cervus nippon were recorded in 2010 and 2018 in Betula forests and tall grassland communities in a subalpine zone, central Japan. Species composition differed significantly between vegetation types in both censuses. The α-diversity had declined significantly in both vegetation types. Metrics related to species replacement made a greater contribution to β-diversity than those related to nestedness in both vegetation types. A decrease of β-diversity based on incidence data from 2010 to 2018 in the Betula forests indicated that floristic homogenization had occurred; an increase of β-diversity based on abundance data from 2010 to 2018 in the grasslands indicated that floristic differentiation had occurred. Changes of α-diversity in both vegetation types and of β-diversity in the grasslands were significantly correlated with grazing intensity. These results showed that deterministic processes, which originally differed between the Betula forests and grasslands, would be the dominant causes of floristic changes under deer-grazing pressure.

The lower storeys of main tree species in deciduous pioneer tree stands of fertile sites: case of Lithuania

Forest ecosystems face challenges of climate change and the pressure of economic activity on biodiversity. As European policies turn into Green Deal, ecological forestry systems, which aim to increase or at least not reduce biodiversity while maintaining high forest productivity, are becoming particularly relevant. This study examines distribution regularities of the lower storeys of main tree species in fertile not wet habitats of forest communities composed of pioneer deciduous tree species, the understanding of which will allow the development of forestry systems that exploit the natural forest regeneration potential. We used stand-wise forest inventory data on Betula spp., Populus tremula, Alnus incana mature and overmatured stands. We analysed how lower storeys are distributed in the stands of different tree species according to soil conditions, the age, stocking level and mixture. We found that most of stands are not in the second story and understory, from which new stands can be formed. Betula forests have the greatest potential for regeneration, and Alnus incana forests have the lowest one. The most important species of the second story and understory is Picea abies, rarer Fraxinus excelsior and Tilia cordata, other species are more random. With an increasing forest mixture, the second story and understory are found more often. To reduce clear-cutting in the fertile forests of pioneer tree species in forestry, we need to focus on measures to allow the development of lower storeys of the major climax tree species. Keywords: ecological forestry, forest succession, fertile site type, pioneer tree stands, temperate hemiboreal forests.

A Comparative Pattern for Populus spp. and Betula spp. Stand Biomass in Eurasian Climate Gradients

Based on the generated database of 413 and 490 plots of biomass of Populus spp. and Betula spp. in Eurasia, statistically significant changes in the structure of forest stand biomass were found with shifts in January temperatures and average annual precipitation. When analyzing harvest data, the propeller-shaped biomass patterns in the gradients of average annual precipitation and average January temperatures are obtained, which are common for both deciduous species. Correspondingly, Populus and Betula forests show a regularity common to the biomass components: in the cold zones the precipitation increase leads to the increase of biomass, and in the warm ones to their decrease. In wet areas, the increase of temperature causes the decrease of biomass, and in dry areas, it causes their increase. In accordance with the law of the limiting factor by Liebig-Shelford, it is shown that both an decrease in temperature in dry conditions and a increase in precipitation in a warm climate lead to a decrease in the biomass of trees.

Habitat selection of large herbivores evidenced as threats to alpine ecosystem

Across the globe, increasing populations of Cervidae have the potential to modify ecosystems. Long-term grazing pressure by deer not only alters vegetation but also affects ecosystem functions and interspecific interactions. It is recognized as a significant factor in ecological degradation. Alpine vegetation (i.e., alpine meadow) is an icon of alpine ecosystems and has thrived for centuries without the presence of large herbivores in Japan. However, in the alpine zone (>2700 m a.s.l.) of the South Alps National Park in central Honshu, Japan, sika deer (Cervus nippon) were first seen in the 1990s; thereafter, the vegetation noticeably changed starting in the 2000s. Nonetheless, virtually no information exists on habitat selection by these alpine sika deer. Here we analyzed (1) the altitudinal movement patterns of alpine sika deer, (2) the significant environmental factors affecting their habitat selection, and (3) estimated the relative probability of their habitat use via resource selection functions (RSF). The mean altitudinal difference between summer and winter home ranges was 1186 m, and the alpine sika deer arrived at the alpine ridgeline in June when the snow cover at >2400 m a.s.l. rapidly decreased. The mean altitude in the summer home range was 2635 ± 135 m. Alpine meadow, followed by Betula forests and tall grasslands, were preferred habitats by deer. The deer also preferred areas where snow melted in late spring and early summer. The deer's core habitat, indicated by higher RSF values (≥0.65), covered 45.2% of the study area, mostly distributed in the alpine zone. Our estimates clearly suggest the urgent need to prioritize specific areas for the conservation of the alpine vegetation in the South Alps National Park in Japan.

Quantification of different silicon fractions in broadleaf and conifer forests of northern China and consequent implications for biogeochemical Si cycling

The terrestrial biogeochemical silicon (Si) cycle significantly contributes to maintaining the functions and sustainability of terrestrial ecosystems. Over the short term, the biogeochemical Si cycle can be strongly influenced by dissolved Si, organic bound Si, Si adsorbed to pedogenic oxides/hydroxides, and biogenic and pedogenic amorphous Si. However, quantitative studies about these relatively soluble Si fractions are rare. In this study, we quantified different Si fractions in the 0–10 cm, 10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm soil layers of broadleaf forests (Betula forest and Quercus forest) and conifer forests (Larix forest and Pinus forest) in northern China using a sequential chemical extraction scheme optimized for these Si fractions. The results showed that the total Si (Sit) in the soil layers consisted of 97.7–98.5% crystalline Si (Sicry) and 1.5–2.3% non-crystalline Si (Sinoncry) fractions. Within the Sinoncry fraction, the proportions of dissolved Si (Sidis), organic matter bound Si (Siorg), pedogenic oxides/hydroxides chemisorbed Si (Sisorb), and amorphous Si (Siamor) were 3.4–6.7%, 5.5–8.9%, 6.3–8.5%, and 77.7–84.8%, respectively. Although the Sidis fraction was the least abundant component, it is at the center of the interconversion processes among the different Sinoncry fractions. The Siamor fraction was the largest component of Sinoncry and was composed of 37.7–71.9% biogenic amorphous Si (Sibio-amor) and 28.1–62.3% pedogenic amorphous Si (Siped-amor). Our study indicated that i) Siped-amor fraction is more easily influenced by soil pH comparing to Sibio-amor fraction; ii) the Sibio-amor fraction contributes more to the biogeochemical Si cycle in broadleaf forests, whereas the Siped-amor fraction contributes more in conifer forests; and iii) soil pH, soil organic matter, and plant community differences can influence the vertical distribution of the different Sinoncry fractions and thus affect the multiple transformation processes among these Si fractions in studied forests.

Sapwood biomass carbon in northern boreal and temperate forests

AbstractAimInformation on the amount of carbon stored in the living tissue of tree stems (sapwood) is crucial for carbon and water cycle applications. Here, we aim to investigate sapwood‐to‐stem proportions and differences therein between tree genera and derive a sapwood biomass map.LocationNorthern Hemisphere boreal and temperate forests.Time period2010.Major taxa studiedTwenty‐five common tree genera.MethodsFirst, we develop a theoretical framework to estimate sapwood biomass for a given stem biomass by applying relationships between sapwood cross‐sectional area (CSA) and stem CSA and between stem CSA and stem biomass. These measurements are extracted from a biomass and allometry database (BAAD), an extensive literature review and our own studies. The established allometric relationships are applied to a remote sensing‐based stem biomass product in order to derive a spatially continuous sapwood biomass map. The application of new products on the distribution of stand density and tree genera facilitates the synergy of satellite and forest inventory data.ResultsSapwood‐to‐stem CSA relationships can be modelled with moderate to very high modelling efficiency for different genera. The total estimated sapwood biomass equals 12.87 ± 6.56 petagrams of carbon (PgC) in boreal (mean carbon density: 1.13 ± 0.58 kgC m−2) and 15.80 ± 9.10 PgC in temperate (2.03 ± 1.17 kgC m−2) forests. Spatial patterns of sapwood‐to‐stem biomass proportions are crucially driven by the distribution of genera (spanning from 20–30% in Larix to > 70% in Pinus and Betula forests).Main conclusionsThe presented sapwood biomass map will be the basis for large‐scale estimates of plant respiration and transpiration. The enormous spatial differences in sapwood biomass proportions reveal the need to consider the functionally more important sapwood instead of the entire stem biomass in global carbon and water cycle studies. Alterations in tree species distribution, induced by forest management or climate change, can strongly affect the available sapwood biomass even if stem biomass remains unchanged.

The rare Holsteinian (Mazovian) interglacial limnic deposits in the Książnica outcrop at Krzczonów (near Świdnica), Sudetic Foreland

The article presents the results of research on peats, muds and sands filling a palaeocavity within alluvial fans of the Bystrzyca River valley, in the Sudetic Foreland of SW Poland. In the 534-cm deep research profile in the central part of a palaeolake, 267 samples were collected at an interval of 2 cm and lithologically (structural and textural studies), palaeobotanically (studies of diatoms, pollen plant macrofossils and fossil wood), palaeozoologically (Cladocera, Mollusca and Ostracoda), geochemically (chemical elements and isotopes) and palaeomagnetically analyzed.The profile consists of three parts: organic with mineral layers (lower), mineral (middle), and organic (upper). The palynological diagram was divided into three zones that represent local sets of pollen zones. This diagram, although incomplete, is clearly indicative of the younger part of the Holsteinian (Mazovian: pollen III and IV periods interglacial). The upper part of the diagram consists of four local pollen zones that are correlated with stadial and interstadial periods. Analysis of several samples of fossil wood shows the widespread presence of Pinus remains and numerous fragments of rhytidome (bark) of Betula. Development of the peat layer (1.36–0.68 m depth) started with paludification of the forest with the Betula forest. Analysis of Cladocera shows the presence of chitin armor components (species: Chydorus sphaericus, Alona rectangula and ephippia of Alona rectangula) in three samples.Lithological, Cladocera and palaeo-magnetic research, supported by geochemical studies, indicate the existence of at least three main phases. The lake originated during the younger part of the Holsteinian (Mazovian) Intergalcial as an oxbow within the valley, where the deposition of variously thick (up to 1.5 m depth) peats, organic and minerogenic silts (the first stage). In the second phase, a closed, fairly deep late Holsteinian lake continued to exist under relatively warm conditions with mainly mineral deposition from the slope. The lake became shallower and wider, and then more open and better oxygenated (with through-flow). In the final phase the lake was completely filled by organic sediments under interglacial conditions. The absence of diatom, molluscan and ostracod communities indicates an acid lacustrine environment at this time. The fluvial and limnic deposits are sealed by overlaying Saalian (Odranian) till.

Phytolith accumulation in broadleaf and conifer forests of northern China: Implications for phytolith carbon sequestration

Carbon (C) occlusion within phytoliths (PhytOC) has a significant potential for long-term C sequestration in forest ecosystems. To unravel the role of forest composition on phytolith production, soil phytolith distribution, and phytolith C sequestration in soils, we investigated community composition and examined phytoliths and PhytOC of mature leaves or needles of dominant trees and understory herbs, as well as soil profiles (50cm depth) within Quercus, Betula, Larix and Pinus forest ecosystems of northern China. Results showed that herb layers contributed 72%, 52%, 40%, and 5% to the flux of phytolith production within Betula forest (18.0±1.26kgha−1yr−1), Quercus forest (28.5±0.77kgha−1yr−1), Larix forest (37.7±1.80kgha−1yr−1) and Pinus forest (16.9±0.30kgha−1yr−1), respectively. The distribution pattern of soil phytoliths from topsoil to subsoil could be classified into three types: significantly decreasing pattern (Betula forest and Quercus forest), non-significantly decreasing pattern (Larix forest), and initially increasing and then decreasing pattern (Pinus forest). Within 0–50cm soil depth, the PhytOC storage of Betula forest, Quercus forest, Larix forest and Pinus forest were 0.29±0.02tha−1, 0.67±0.03tha−1, 0.46±0.03tha−1 and 0.37±0.02tha−1, respectively. Moreover, the soil PhytOC turnover times of these four forest types were estimated to be 537,503,363 and 560year, respectively, which were at least 8–20 times slower than soil organic carbon contributing to climate change mitigation. Overall, our findings indicate that composition of the forest community controls the production flux of phytoliths and the distribution of soil phytoliths, and influences the biogenic silica and its coupled carbon cycles.

Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai–Tibetan Plateau, China

Abstract. We present the results of pollen analyses from a 1105 cm long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed humid period in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly in-phase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño–Southern Oscillation strength in the tropical Pacific.

FOREST STRUCTURE AND REGENERATION PATTERN OF BETULA UTILIS D. DON IN MANASLU CONSERVATION AREA, NEPAL

Forest structure and regeneration of Betula utilis (D. Don) was studied in birch forestlocated in Samagaun valley (3500 – 4000 m) of Manaslu Conservation Area. Vegetationsampling was done by quadrat method. Altogether 40 quadrats were sampled to determinethe Importance Value Index (IVI) of tree species, and distribution pattern of seedlings andsaplings. Regeneration was assessed by density - diameter curve. Four tree species wererecorded from the forest. Betula utilis was the dominant tree species with the highestImportance Value Index (173.22) in mixed Betula forest and 262.96 in pure Betula forestand Abies spectabilis was the co – dominant species (65.95) in mixed Betula forest whileRhododendron campanulatum was the co-dominant species (37.03) in pure Betula forest.Density of Betula utilis increased with increase in elevation where as density of other treespecies decreased with increase in elevation. Mixed Betula forest at lower elevation wasyoung. The density diameter curve of the tree population of Betula utilis, both on mixed andpure forests, deviated slightly from the typical reverse J shaped structure and hence did notshow the sustainable regeneration. The sapling density was higher than seedling density.The distribution of seedlings and saplings were not uniform among the sampling plots.DOI: http://dx.doi.org/10.3126/eco.v20i0.11472ECOPRINT An International Journal of EcologyVol. 20, 2013page: 107-113

Environmental variability in the monsoon–westerlies transition zone during the last 1200 years: lake sediment analyses from central Mongolia and supra–regional synthesis

A high resolution multi–proxy (pollen, grain size, total organic carbon) record from a small mountain lake (Lake Khuisiin; 46.6°N, 101.8°E; 2270 m a.s.l.) in the south–eastern Khangai Mountains of central Mongolia has been used to explore changes in vegetation and climate over the last 1200 years. The pollen data indicates that the vegetation changed from dry steppe dominated by Poaceae and Artemisia (ca AD 760–950), to Larix forest steppe (ca AD 950–1170), Larix–Betula forest steppe (ca AD 1170–1380), meadow dominated by Cyperaceae and Poaceae (ca AD 1380–1830), and Larix–Betula forest steppe (after ∼ AD 1830). The cold-wet period between AD 1380 and 1830 may relate to the Little Ice Age. Environmental changes were generally subtle and climate change seems to have been the major driver of variations in vegetation until at least the early part of the 20th century, suggesting that either the level of human activity was generally low, or the relationship between human activity and vegetation did not alter substantially between AD 760 and 1830. A review of centennial–scale moisture records from China and Mongolia revealed that most areas experienced major changes at ca AD 1500 and AD 1900. However, the moisture availability since AD 1500 varied between sites, with no clear regional pattern or relationship to present–day conditions. Both the reconstructions and the moisture levels simulation on a millennium scale performed in the MPI Earth System Model indicate that the monsoon–westerlies transition area shows a greater climate variability than those areas influenced by the westerlies, or by the summer monsoon only.

Postglacial vegetation history as recorded from the subalpine Lake Ribno (NW Rila Mts), Bulgaria

AbstractA pollen analysis conducted on a 600 cm core from Lake Ribno (2184 m) in the Northwestern Rila Mountains, supplemented by 13 radiocarbon dates, has revealed the basic stages in its postglacial vegetation dynamics. The lateglacial vegetation, composed of Artemisia, Chenopodiaceae and Poaceae, with stands of Pinus and Juniperus-Ephedra shrubland, dominated in the stadials and partly retreated during the Bølling/Allerød interstadial (14700–12900 cal. yrs. BP). The afforestation in the early Holocene (11600–7800 cal. yrs. BP) started with pioneer Betula forests, with groups of Pinus and Juniperus at mid-high altitudes, and Quercus forests with Tilia, Ulmus, Fraxinus, Corylus below the birch zone. A coniferous belt composed of Pinus sylvestris, P. peuce and Abies was shaped under the conditions of a more humid climate (7800–5800 cal. yrs. BP). The last trees that invaded the study area were Fagus after 4300 cal. yrs. BP and Picea abies after 3400 cal. yrs. BP. Evidence for destructive changes in the vegetation and indications of agricultural and stock-breeding activities (pollen of Triticum, Secale, Plantago lanceolata, Rumex, Juglans) was continuously recorded since the Late Bronze Age (3400–3200 cal. yrs. BP). The postglacial vegetation history in the Northwestern Rila Mountains demonstrated close similarities with that of the Northern Pirin Mountains.

Changes in biodiversity and vegetation composition in the central Swiss Alps during the transition from pristine forest to first farming

AbstractAimWe investigate the response of vegetation composition and plant diversity to increasing land clearance, burning and agriculture at the Mesolithic–Neolithic transition (c. 6400–5000 bc) when first farming was introduced.LocationThe Valais, a dry alpine valley in Switzerland.MethodsWe combine high‐resolution pollen, microscopic charcoal and sedimentological data to reconstruct past vegetation, fire and land use. Pollen evenness, rarefaction‐based and accumulation‐based palynological richness analyses were used to reconstruct past trends in plant diversity.ResultsOur results show that from c. 5500 cal. yr bc, slash‐and‐burn activities created a more open landscape for agriculture, at the expense of Pinus and Betula forests. Land clearance by slash‐and‐burn promoted diverse grassland ecosystems, while on the long term it reduced woodland and forest diversity, affecting important tree species such as Ulmus and Tilia.Main conclusionsUnderstanding the resilience of Alpine ecosystems to past disturbance variability is relevant for future nature conservation plans. Our study suggests that forecasted land abandonment in the Alps will lead to pre‐Neolithic conditions, with significant biodiversity losses in abandoned grassland ecosystems. Thus, management measures for biodiversity, such as ecological compensation areas, are needed in agricultural landscapes with a millennial history of human impact, such as the non‐boreal European lowlands. Our study supports the hypothesis that species coexistence is maximized at an intermediate level of disturbances. For instance, species richness decreased when fire exceeded the quasi‐natural variability observed during the Mesolithic times. Under a more natural disturbance regime, rather closed Pinus sylvestris and mixed oak forests would prevail.

Effects of browsing by sika deer (Cervus nippon) on subalpine vegetation at Mt. Kita, central Japan

AbstractThe effects of browsing by sika deer (Cervus nippon) on subalpine vegetation (Betula forests and tall grasslands) were investigated in the South Alps National Park, Japan. The browsing ratio (the number of browsed quadrats to the number of quadrats occurring in each plot) was significantly higher in Betula forests than in grasslands. A significant negative correlation was found between the browsing ratio and some species diversity indices (number of species and the Shannon–Wiener diversity index) in the Betula forests, but not in grasslands. The frequency of occurrence and the number of preferred browse species were significantly higher in Betula forests than in grasslands. Browsing was not always the most serious on the most frequent vegetation. For example, Polemonium caeruleum L. subsp. yezoense var. nipponicum, which is listed as vulnerable on Japan's red list of threatened species and was low in occurrence in Betula forests compared to grasslands, was more browsed in Betula forests than in grasslands. Less frequently occurring species subjected to more browsing could easily disappear. The disappearance of such species would exert a strong effect on the species pool in the area.

Palaeoenvironment of the Late Pleistocene – Holocene interval in the Tanalyk river valley of the Southern Trans-Ural region (Russia)

Abstract Palaeoenvironmental reconstruction of the Tanalyk River valley (Trans-Uralian area, Bashkortostan Republic, Russia) between the Late Pleistocene and the Late Holocene has been established through biostratigraphic investigations. The Tanalyk Bronze Age settlement is located on the first overflood terrace of the Tanalyk River. From the base to the top, this terrace consists of fluvial and lacustrine deposits of the Tabulda horizon, water-slope deposits of the Kudashevo horizon (Late Pleistocene), and subaerial deposits of the Middle and Upper Holocene. During the Late Pleistocene, open landscapes covered by herbs- Artemisia -Chenopodiaceae meadow-steppe associations with Ephedra sp. admixture dominated. Betula and Pinus forests grew in small areas. Picea with Polypodiaceae understory grew in humid valleys. The climate was warm and dry during the Tabulda and cold during the Kudashevo. The subaerial Holocene deposits (soil and cultural layer) were correlated with the Boreal and Subboreal periods of the Blytt–Sernander scale. The late Subboreal climate was cold and dry. The vegetation of this period was represented by Artemisia-Chenopodiaceae steppe and by small Pinus forests with Betula, Tilia and Alnus . The climate of the Subatlantic was wet at the beginning and drier at the end. The vegetation of this period was represented mainly by the Artemisia steppe associations. Small mammals, and land and freshwater mollusc remains have been discovered in the same deposits and complete the palaeoecological characteristic of these periods. A cultural layer has been dated at 2830 ± 110 BP LU-3713 on bones of Equus sp. Numerous Holocene large mammal remains have been found in the cultural layer deposits, dated to Subboreal-3. The large Holocene mammal fauna is constituted of eurybiotic species and species of semi-open landscapes. Bone remains of domestic animals dominate in the collection. Pastoral farming constituted the base of the economy of this ancient people, and the role of hunting was small. The investigated area is now covered by the waters of the Tanalyk water reservoir.

A tephrochronology for the Lateglacial palynological record of the Endinger Bruch (Vorpommern, north‐east Germany)

AbstractThe tephrostratigraphy of lake sediments in the Endinger Bruch provides the first robust age model for the Lateglacial palynological records of Vorpommern (north‐east Germany). Cryptotephra investigations revealed six tephra layers within sediments spanning from Open vegetation phase I (∼Bølling, ∼15 ka) to the Early Holocene Betula/Pinus forest phase (∼Pre‐boreal, ∼10.5 ka). Four of these layers have been correlated with previously described tephra layers found in sites across Europe. The Laacher See Tephra (Eifel Volcanic Field) is present in very high concentrations within sediments of the Lateglacial Betula (/Pinus) forest phase (∼Allerød). The Vedde Ash (Iceland) lies midway through Open vegetation phase III (∼Younger Dryas). The Hässeldalen and the Askja tephras (Iceland) lie in the Early Holocene Betula/Pinus forest phase (∼Preboreal). These tephra layers have independently derived age estimates, which have been imported into the Endinger Bruch record. Furthermore, the layers facilitate direct correlation of the regional vegetation record with other palaeoenvironmental archives, which contain one or more of the same tephra layers, from Greenland to Southern Europe. In doing this, localized variations are confirmed in some aspects of the pollen stratigraphy; however, transitions between the main vegetation phases appear to occur synchronously (within centennial errors) with the equivalent environmental transitions observed in sites across the European continent. Copyright © 2011 John Wiley & Sons, Ltd.

Determinism versus chance in canopy gap herbaceous species assemblages in temperate Abies– Betula forests

It is not known if the species composition of herbaceous plant assemblies within tree-fall gaps is determined stochastically or whether it follows species-specific and environmentally-determined patterns. We applied three methods, fitting species abundance distribution models, comparing community similarities, and testing species–environmental variable association, to evaluate the relative importance of chance and deterministic rules in controlling herbaceous composition within canopy gaps in the Abies– Betula forests of Mt. Taibai, Central China. Herbaceous species abundance within canopy gaps was well fit by a neutral model, showing that relative abundance was qualitatively consistent with stochastic processes. Although species composition in gaps significantly differed from closed canopy sites (ANOSIM, R = 0.509, p = 0.001), there were no significant differences among gaps of different age groups (ANOSIM, R = 0.035, p = 0.191) or gaps of different size groups (ANOSIM, R = 0.089, p = 0.057). Similarly, gaps of similar age and size did not show significantly higher similarity ( χ 2 = 2.30, df = 3, p = 0.513) in species composition than gaps of distinct age or size. Moreover, there were only eight species, including two light-demanding species, confined to larger gaps among the 69 species, and only an additional seven species found more commonly in larger gaps, whereas most herbaceous species were gap size generalists. Canonical correspondence analysis and random permutation tests suggested that only 27% of species with abundance ⩾5 were associated with environmental variables in gaps. In summary, the species composition in gaps was not constrained significantly by gap traits; rather species were distributed stochastically, likely through by random dispersal and recruitment limitation of species from the surrounding available species pool. Measures that introduce gap disturbance, such as selective harvesting, are still recommended when the maintenance of total biodiversity in forests is a concern.

A 16 000‐year record of vegetational change in south‐western Alaska as inferred from plant macrofossils and pollen

AbstractPollen and macrofossil analyses of a sediment core from Beaver Pond (60° 37′ 14″ N, 154° 19′ W, 579 m a.s.l.) reveal a record of regional and local postglacial vegetation change in south‐western Alaska. The chronology is based on five AMS (accelerator mass spectrometry) 14C ages obtained from terrestrial plant macrofossils. Pollen and macrofossil records suggest that open herb and shrub tundra with e.g. Poaceae, Cyperaceae, Artemisia, Vaccinium and Salix prevailed on the landscape before ca. 14 000 cal a BP. The shift from herb‐ to shrub‐dominated tundra (Salix, subsequent Betula expansion) possibly reflects climatic warming at the beginning of the Bølling period at ca. 14 700–14 500 and around 13 500 cal a BP. Vegetation (Betula shrub tundra) remained relatively stable until the early Holocene. Macrofossil influx estimates provide evidence for greater biomass in Betula shrub tundra during the early postglacial period than today. Charcoal accumulation rates suggest tundra fire activity was probably greater from ca. 12 500 to 10 500 cal a BP, similar to results from elsewhere in Alaska. The pollen and macrofossil records of Beaver Pond suggest the prevalence of low shrub tundra (shrub Betula, Betula nana, Vaccinium, Ledum palustre, Ericaceae) and tall shrub tundra (Alnus viridis ssp. crispa, Salix) between 10 000 and 4000 cal a BP. This Holocene vegetation type is comparable with that of the modern treeless wet and moist tundra in south‐western Alaska. The expansion of Picea glauca occurred ∼4000 cal a BP, much later than that of A. viridis (ssp. crispa), whereas in central and eastern Alaska Picea glauca expanded prior to or coincident with Alnus (viridis). At sites located only 200–400 km north‐east of Beaver Pond (Farewell and Wien lakes), Picea glauca and Betula forests expanded 8000–6000 cal a BP. Unfavourable climatic conditions and soil properties may have inhibited the expansion and establishment of Picea across south‐west Alaska during the mid and late Holocene. Copyright © 2011 John Wiley & Sons, Ltd.