Physiological characteristics of arctic tern Sterna paradisaea chicks in relation to egg volume

The effect of egg volume on body mass, body composition and growth rate in arctic tern Sterna paradisaea chicks was studied at Ny-Ålesund, on Svalbard (78°55'N, 12°00'E), in order to investigate whether differences in egg size influence the physiological characteristics of the hatchlings. The relative content of yolk and albumen in eggs did not vary in proportion to egg volume. Hatchlings from large eggs had larger body masses than hatchlings from small eggs, with 71% of the overall variation in body mass accounted for egg volume. In newly-hatched chicks, water content, lean body and total lipid mass, as well as both leg and pectoral muscles, changed isometrically in proportion to egg volume. Hatchlings from large eggs, however, had disproportionately larger yolk sacs. The leg muscles of small chicks contained a lower proportion of water than the leg muscles of large chicks, indicating that the leg muscles of small hatchlings were functionally more mature. There was a weak, but significant, correlation between egg volume and growth rate. However, a residual analysis made to eliminate the effect of egg volume showed no correlation between hatchling body mass and growth rate. The results of the present study show that Arctic tern hatchlings from large eggs emerge with more yolk sac reserves, enabling them to better withstand periods of food-scarcity. During embryonic growth in small eggs, however, there seems to be a greater relative usage of yolk, resulting in a more developed leg musculature. This may partly compensate for the higher mass-specific heat loss in small hatchlings.     

Abundance and diversity of small mammals in response to various linear habitats in semi-arid agricultural landscapes

We investigated the influence of linear habitats, three types of hedgerows and two types of field margins, on the small mammal community within a semi-arid agricultural landscape in south-central British Columbia, Canada. We examined whether abundance, species richness, and species diversity of small mammals in tree fruit orchards differed from linear, edge habitats along orchard margins. Our five edges spanned grassy to wooded habitats. Linear habitats were intensively sampled for vascular plants in 2003 and small mammal communities from 2003 to 2007. Vegetation and total abundance of small mammal species among three types of hedgerows were similar and population changes followed those within nearby apple orchards. Species richness and diversity of small mammals, however, were significantly higher in hedgerows than orchards. Fewer mammals occupied hedgerows with high volumes of herb and shrub biomass, but richness and diversity of mammals did increase with shrub volume. All seven species of small mammals were represented in the hedgerow communities, including two species at risk: the Great Basin pocket mouse Perognathus parvus and the western harvest mouse (Reithrodontomys megalotis). Two types of field margins (orchard-sagebrush and orchard-old field) along fencerows provided habitat for P. parvus. Field margins managed for herbaceous plant species along fencerows and other such linear configurations provided habitat for R. megalotis. Linear non-crop habitats should maintain the overall small mammal community, as well as the two species at risk, within this semi-arid agricultural landscape.     

Thick moss layers and high cover of grasses: Potential threats to herb diversity in hay meadows in Norway

In an old, species-rich hay meadow in Varalds?y in Hardanger, the only known remaining managed site of its kind in West Norway, the moss layer is increasing in thickness in some places. Thick moss is associated with a high cover of monocotyledons, while a low cover of monocotyledons is associated with high numbers of herbs, including vulnerable species, which mainly occur in herb-rich areas. The increase in moss is probably caused by a reduction in both traditional means of moss removal and in sheep trampling and it may represent a potential threat to plant species diversity in traditionally managed hay meadows in the region. In order to increase the area of open, species-rich hay meadows, and thus the potential population sizes for indicator species of traditional management, increased grazing intensity (back to traditional levels) and removal of mosses during haymaking is recommended. The study demonstrates that, for conservation purposes, it is not easy to replicate past conditions unless the details of traditional management practices are known and understood, and these are now passing from general knowledge.     

Abundance and diversity of small-bird assemblages in the Monte desert, Argentina

Assemblages of small bird species (<90 g body mass) from the Monte desert in Argentina were studied to analyze spatial and temporal variation in abundance and species richness. Mean species richness was higher during breeding season than in non-breeding season. The same pattern was observed in aerial insectivores, while granivores and substrate insectivores did not differ between breeding and non-breeding seasons. Overall bird abundance was similar across seasons. Species richness was positively correlated with bird abundance and negatively correlated with dominance; bird abundance and dominance were not correlated. These patterns could be explained by distinct responses of functional groups of birds; dominant species were granivores in the non-breeding season and aerial insectivores during the breeding season, and bird abundance in functional groups changed according to food supply. Most species are residents or regular migrants, while there are few nomadic and transient species. Predictable annual fluctuations in rainfall and resource availability should favor a migratory strategy more than nomadic movements. Similarly, breeding is strongly seasonal and most species start breeding when the first summer rains have generally not yet fallen. Finally, concordances in assemblage structure at local and regional scale suggest that similar mechanisms are acting on the local bird assemblages across the Monte.     

Biogeographical patterns of arbuscular mycorrhizal fungi diversity in China's grasslands

Arbuscular mycorrhizal fungi(AMF) are universally mutualistic symbionts that colonize the fine roots of most vascular plants. However, the biogeographical patterns and driving factors of AMF diversity of plant roots in grasslands are not well investigated. In this study, we used high-throughput sequencing techniques and bioinformatics to evaluate the AMF richness of 333 individual plant roots in 21 natural grassland ecosystems in northern China, including the Loess Plateau(LP), the Mongolian Plateau(MP), and the Tibetan Plateau(TP). The AMF richness showed a significant parabolic trend with increasing longitude. In regional situations, the AMF richness in the grasslands of the MP(60.4 ± 1.47) was significantly higher than those of the LP(46.4 ± 1.43) and TP(44.3 ± 1.64). Plant traits(including plant families, genera, and functional groups) explained the most variation in the AMF richness across China's grasslands, followed by energy and water; soil properties had the least effects. The results showed the biogeographical patterns of the AMF richness and the underlying dominant factors, providing synthetic data compilation and analyses in the AMF diversity in China's grasslands.     

Farm size and landscape composition in relation to landscape changes in Denmark

Geografisk Tidsskrift, Danish Journal of Geography 106(2): 45–59, 2006

This paper explores relationships between farm size and landscape composition in terms of densities of uncultivated landscape elements and sizes of agricultural fields. The study is based on national agricultural registers for Denmark and on aerial photo interpretation of three study areas, representing different Danish landscape types. Results indicate significantly smaller fields and significantly higher densities of uncultivated landscape elements on small farms (<25 ha). At national level, current differences between small and large farms are to some extent caused by landscape changes between 1998 and 2004. Analyses of the study areas indicate that current differences between small and large farms mainly evolved between 1982 and 2002, while the influences of changes between 1954 and 1982 are limited. Relationships between farms size and landscape composition are independent of spatial variations in soil type and slope conditions. Consequently, attention must be paid to other parameters linked to farm size. In particular, the effects on landscape composition of part-time and hobby farming, as well as production type, must be considered.     

Fluvial diversity in relation to valley setting in the source region of the Yangtze and Yellow Rivers

The spatial distribution of valley setting （laterally-unconfined, partly-confined, or confined） and fluvial morphology in the source region of the Yangtze and Yellow Rivers is contrasted and analyzed. The source region of the Yangtze River is divided into 3 broad sections （I, II and III） based on valley setting and channel gradient, with the upstream and downstream sections being characterized by confined （some reaches partly-confined） valleys while the middle section is characterized with wide and shallow, laterally-unconfined valleys. Gorges are prominent in sections I and III, while braided channel patterns dominate section II. By contrast, the source region of the Yellow River is divided into 5 broad sections （sections I-V） based on valley characteristics and channel gradient. Sections I, II and IV are alluvial reaches with mainly laterally-unconfined （some short reaches partly-confined） valleys. Sections III and V are mainly confined or partly-confined. Greater morphological diversity is evident in the source region of the Yellow River relative to the upper Yangtze River. This includes braided, anabranching, anastomosing, meandering and straight alluvial patterns, with gorges in confined reaches. The macro-relief （elevation, gradient, aspect, valley alignment and confinement） of the region, linked directly to tectonic movement of the Qinghai-Tibet Plateau, tied to climatic, hydrologic and biotic considerations, are primary controls upon the patterns of river diversity in the region.     

From small sets of GPS trajectories to detailed movement profiles: quantifying personalized trip-dependent movement diversity

ABSTRACT

The ubiquity of personal sensing devices has enabled the collection of large, diverse, and fine-grained spatio-temporal datasets. These datasets facilitate numerous applications from traffic monitoring and management to location-based services. Recently, there has been an increasing interest in profiling individuals' movements for personalized services based on fine-grained trajectory data. Most approaches identify the most representative paths of a user by analyzing coarse location information, e.g., frequently visited places. However, even for trips that share the same origin and destination, individuals exhibit a variety of behaviors (e.g., a school drop detour, a brief stop at a supermarket). The ability to characterize and compare the variability of individuals' fine-grained movement behavior can greatly support location-based services and smart spatial sampling strategies. We propose a TRip DIversity Measure --TRIM – that quantifies the regularity of users' path choice between an origin and destination. TRIM effectively captures the extent of the diversity of the paths that are taken between a given origin and destination pair, and identifies users with distinct movement patterns, while facilitating the comparison of the movement behavior variations between users. Our experiments using synthetic and real datasets and across geographies show the effectiveness of our method.     

中国Holdridge生命地带及其多样性的时空变化分析

在分析目前生态地理模型及其实现方法基础上,提出基于ARC/INFO与VC++综合集成的先插值再运行生命地带模型的方法和技术路线,克服了以前模型实现过程中所存在的局限性。利用中国1962～2002年735个站点逐日温度与降水量观测数据,通过对Holdridge生命地带模型和生态多样性模型进行模拟运算后获得中国Holdridge生命地带时空分布序列图及生命地带多样性序列数值。对模拟运算,结果分析发现:生命地带类型变化随着气候条件的变化与土地覆被变化存在很好的对应关系,生命地带多样性与年均生物温度、年降水量均呈现出震荡波动的变化模式。另外对中国Holdridge生命地带的多样性、连通性及斑块形状等景观指数进行计算分析,讨论了生命地带多样性与生态环境稳定性之间的相关关系。     

Chemical denudation in arctic-alpine Latnjavagge (Swedish Lapland) in relation to regolith as assessed by radio magnetotelluric-geophysical profiles

In Latnjavagge, a 9-km² drainage basin with homogeneous lithology in periglacial northern Swedish Lapland, water balance, water chemistry and radio magnetotelluric geophysical investigations along selected profiles were integrated with assessment of regolith thickness as well as of ground frost conditions within the basin. In combination with direct field observations, the geophysical profiles demonstrated presence of relatively thin regolith in most of the investigated area, yet in some parts, the bedrock was located deeper and locally was not detected at 40-m depth. TDS values of the water were generally very low. The areas that contributed with the lowest ion concentrations were cold and had a thin regolith, whereas there were higher concentrations in water that drained radiation exposed slopes with earlier thaw and thicker regolith. The low resistivities found along the profiles in the geophysical investigations in combination with the relatively higher TDS values found in related runoff and subsurface water samples showed that larger volumes of ice-rich frozen ground were not found along the investigated profiles in late August.     

The relation between accessibility,diversity and indigenous valuation of vegetation in the Bolivian Andes

A quantitative ethnobotanical study was conducted in the semi-arid Bolivian Andes community of Apillapampa to evaluate the impact of site accessibility on the diversity and perceived usefulness of (sub-)woody plants. Vegetation was sampled in thirty-six transects of 50 × 2 m², whereas data on plant uses were obtained from 13 local Quechua participants. Accessibility of sample sites correlated negatively with plant diversity, but positively with perceived usefulness. Hence, in spite of being less diverse, vegetation of more accessible sites was perceived as more useful to people than vegetation of more remote and also more diverse sites. This result contributes to the validity of the widely accepted notion that “more accessible plant resources are more useful to people”, not only at the level of individual plant species, but also for entire vegetation communities. In this respect, our finding that people attribute an equal usefulness to the vegetation of two local ecological zones (i.e. prepuna and puna) most likely reflects their similar accessibility from the village centre, which is located on the edge between both zones.     

Holocene trophic state changes in relation to sea level variation in Lake Blanca, SE Uruguay

Paleolimnological data are presented relating trophic development to sea level variation in Lake Blanca, a small (0.6 km²), coastal fresh waterbody in southern Uruguay. Using a sediment core that extended to 7300 years BP, analyses of grain size, thin sections, organic matter, carbonate, total carbon, nutrients, diatoms and palynomorphs, allowed us to infer changes in trophic state and paleosalinities, which were closely related to Holocene sea level variation. Higher trophic states were observed during regressive events, most probably due to increases in runoff and erosion as regression progressed. Four diatom association zones (DAZ) were identified in the sediment core. The basal core section pre-dated the first Holocene marine transgression, contained no diatoms, chrysophyte cysts or non-siliceous microalgae, and showed C/N ratios values higher than 20. Thus, it is likely that the system exhibited terrestrial characteristics. In the second section (6500–2200 years BP, following the first Holocene transgression), there was dominance of marine/brackish diatom species. The lowest trophic states of the core were observed in this section. The third section (2200–1100 years BP), represented the system as it became separate from the Atlantic Ocean, and showed a dominance of brackish/freshwater species and increases in trophic state were observed. In the last section (after 1100 years BP), the system became fully freshwater as no marine or brackish diatom species were found, but a trend to oligotrophication was observed, probably due to nutrient depletion. However, after 1967 AD, eutrophication intensified because of forestry and soil fertilization in the catchment. Pollen association zones (PAZ) allowed us to identify four sections. Below 250 cm (2200 years BP), the core contained no pollen grains as redox potential and pH values were not conducive for pollen preservation. After 2200 years BP (when the system started to separate from the ocean), xerophilic taxa typical of coastal dunes colonized the catchment. Only after 1100 years BP (after fully freshwater conditions established) pollen grains of trees were observed.     

Water chemistry and its diversity in relation to local factors in the Latnjavagge drainage basin, arctic–oceanic Swedish Lapland

The chemistry of precipitation, snow pack and surface water has been analysed on 205 samples collected during the 2001 field season at 25 selected sites within the Latnjavagge drainage basin in arctic–oceanic northern Swedish Lapland. Additionally, daily discharge and yield of dissolved solids have been calculated for several subcatchments and the entire Latnjavagge catchment during the years 2000, 2001 and 2002. Chemical water analysis included the components Ca²⁺, Mg²⁺, Na⁺, K⁺, Fe²⁺, Mn²⁺, Cl⁻, NO₃⁻, SO₄²⁻ and PO₄³⁻, with SO₄²⁻ and Ca²⁺ being the dominant ones in the surface water. Solute concentrations and chemical denudation were low, but showed significant differences within the basin. In areas of shade, longer snow cover, frozen ground and thin regolith, concentrations over the summer were perceptible but so low that solutes brought into the basin from precipitation could be detected in the surface water. In one locality, it was even found that lake water could reflect snowmelt to such an extent that the solute concentration was less than that of summer precipitation. The highest concentrations were found at a radiation-exposed, W-facing, vegetated, moderately steep slope with relatively thick regolith that was thawed at the time of snowmelt in early June. In such well-drained sites with continuous subsurface water flow, a maximum of contact between water and mineral particles could take place. The concentration values revealed differences in the rate of thawing of frozen ground between shaded areas and/or areas at higher altitude on the one hand and radiation-exposed areas on the other. A comparison with published results from Kärkevagge a few kilometres to the northwest as well as from other periglacial locations indicates that the chemical denudation values from Latnjavagge are more representative of periglacial oceanic environments than the values from the Kärkevagge catchment, which shows especially high chemical denudation rates. The investigation in Latnjavagge stresses the importance of spatial variability within even small catchments of homogeneous lithology as it demonstrates that solute concentrations from different subbasins can differ substantially dependent on exposure to radiation, duration of snow cover and frozen ground conditions, regolith thickness and possibly also to vegetation cover and slope angle as factors steering water turbulence and retention of drainage.     

Spatial changes of wind erosion-caused landscapes and their relation with wind field in China

Based on the results of remote sensing investigations of the landscapes of 1995 and 2000, the national distribution of sandy desertified land and its interaction with other landscapes are classified, and five zonal types are distinguished. The data of nationally distributed 400 meteorological stations of 1999 are processed. With the GIS method, the data are spatially interpolated, and the national database of wind field concerned with wind erosion is established. In arid and semi-arid areas of China, the intensity of wind field is one of the key factors that controls the development of landscape especially in desert and its adjacent area. Different indexes are set up to describe the intensity of wind field, the method suggested by the wind erosion prediction models of RWEQ is also adopted to express the intensity of wind. The Weibull distribution is used to describe the wind field in China. Based on the analysis of the process of the wind erosion-driven landscape changes, this article proposes and discusses the control measures of wind erosion.     

Upper Pleistocene and Holocene paleosalinity and trophic state changes in relation to sea level variation in Rocha Lagoon, southern Uruguay

Paleolimnological data are presented on trophic development in relation to sea level variation in Rocha Lagoon, a 72 km² coastal lagoon in southern Uruguay. Using sediment cores that extended to ∼20,000 yr BP, analyses of grain size, organic matter, carbonate, total carbon, nutrients, and diatoms allowed us to infer changes in trophic state and paleosalinities, which were closely related to Holocene relative sea level variation. Higher trophic states were observed during regressive events, most probably due to increases in runoff and erosion as regressions progressed. Diatom Association Zones (DAZ) were identified in both cores. Those DAZ corresponding to transgressive events were dominated by marine/brackish taxa and relatively low organic matter and nutrient values, while those DAZ corresponding to regressive events showed increases in brackish/freshwater diatoms and both organic matter and nutrients. Although the lagoon formed after the first Holocene marine transgression, our data indicate the existence of a marine/brackish aquatic system during upper Pleistocene (i.e., before 15,000 yr BP), but by ∼20,000 yr BP, the system was still likely to be a semi-arid terrestrial system.     

Spatial changes of wind erosion-caused landscapes and their relation with wind field in China

Based on the results of remote sensing investigations of the landscapes of 1995 and 2000, the national distribution of sandy desertified land and its interaction with other landscapes are classified, and five zonal types are distinguished. The data of nationally distributed 400 meteorological stations of 1999 are processed. With the GIS method, the data are spatially interpolated, and the national database of wind field concerned with wind erosion is established. In arid and semi-arid areas of China, the intensity of wind field is one of the key factors that controls the development of landscape especially in desert and its adjacent area. Different indexes are set up to describe the intensity of wind field, the method suggested by the wind erosion prediction models of RWEQ is also adopted to express the intensity of wind. The Weibull distribution is used to describe the wind field in China. Based on the analysis of the process of the wind erosion-driven landscape changes, this article proposes and discusses the control measures of wind erosion.     

Weathering characteristics of arctic islands in northern Norway

The arctic islands of the Lofoten-Vesterålen archipelago in northern Norway have a wide distribution of weathered land surfaces commonly located above 250 m with several apparent similarities. In order to investigate the characteristics of (deep) weathering in this region, northern Langøya and Hadseløya were chosen for in-depth analyses. Eight weathering profiles were excavated from various surfaces, and the stratigraphies were logged in detail. Material was collected throughout the weathering horizons, and all samples were subsequently analysed for clay mineralogy (< 63 μm fraction) and grain size distribution. The sampling strategy was complemented by samples from additional saprolites and other landforms such as moraines and rock glaciers. The XRD results indicate that the presence of secondary minerals, such as gibbsite (Al(OH)₃) and kaolinite (Al₂Si₂O₅(OH)₄), are very common throughout the profiles. Gibbsite is an extreme end product of silicate weathering and usually associated with a warmer and more humid climate, as found in Scandinavia during the Tertiary. The grain size analyses (< 63 μm) show that the finer silt fractions (< 8 μm) tend to be high in the profiles (20–40%), with significant amounts of clay (5–15%) demonstrating that the regolith itself is susceptible to frost sorting mechanisms.¹⁰Be exposure dates from in situ quartz knobs on tors and boulders of local origin suggest > 40,000 years of subaerial conditions. Considering the steady surface erosion, this figure should be viewed as an absolute minimum age estimate. Mapping of the superficial sediments and geomorphological features of the study areas has revealed several common morphological features, which indicate dominance of glacial and periglacial processes in the areas lying below the lower boundary of blockfields (c. 250 m). The weathering mantles are not a periglacial end product, but rather a relict tertiary landform that were modulated by permafrost processes as well as biological processes at later stages. The regolith cover constrain the vertical extension of warm-based Quaternary ice sheets challenging the notion of a parabolic ice mass consuming every mountain top of Lofoten and Vesterålen.     

Species diversity and its relation with soil factors under different site conditions in a desert-oasis ecotone

Vegetation and soil surveys were conducted under different site conditions in 2007–2011 to study species diversity using richness, evenness and diversity indices, in the middle portion of the Heihe River Basin. The relationship between species distribution and soil environmental factors was also studied by Canonical Correspondence Analysis (CCA). Results show that vegetation coverage and species diversity were the highest in the interdune lowland, and the lowest in the mobile dune. Results of the Hill’s index (diversity ordering) shows that species diversity is reduced along decreasing soil water content, and the order of species diversity was interdune lowland, flat slope, fixed dune, semifixed dune and mobile dune. The influence degree of soil factors on vegetation distribution was soil water content > pH > total K > organic matter > available N > total N > available K > total P > saline content > available P. Soil water content and pH were important factors significantly affecting spatial distribution difference of vegetation, the environmental explanation was 98%.     

青藏高原湖泊沉积物硫酸盐还原菌种群分布

采用聚合酶链式反应(PCR,Polymerase Chain Reaction)、变性梯度凝胶电泳(DGGE,Denaturing Gra-dient Gel Electrophoresis)与实时荧光定量聚合酶链式反应(Q-PCR,Quantitative PCR)相结合的综合分析技术,研究了青藏高原洱海、青海湖、尕海1、尕海2、小柴旦湖沉积物硫酸盐还原菌多样性及丰度。研究结果显示,5个盐湖沉积物中dsrB(编码亚硫酸还原酶β亚基,为硫酸盐还原菌所共有)基因的丰度为每克沉积物1.71×108～1.55×109拷贝,与盐度无明显相关性;所获得的dsrB基因序列分属于3个科:Desulfobacter-aceae,Desulfobulbaceae和Peptococcaceae。其中,Desulfobacteraceae科是主要类群。硫酸盐还原菌多样性(DGGE结果)与盐度呈现出负相关性。故在所研究的盐湖中,盐度可能不是影响硫酸盐还原菌种群分布的唯一因素,可能还受其它未知环境因素的影响,有待于进一步研究。     

Land-use/cover changes in relation to stream dynamics in a marginal graben along the northern Ethiopian Rift Valley

This paper investigates land-use/cover changes related to river dynamics in northern Ethiopia. Aerial photographs from 1965 to 1986, and SPOT images of 2007 and 2014 were used to extract land units. Land-use/cover changes took place in 48% of the entire landscape around the river across the last five decades. Changes related to swap accounted for 37%, whereas net changes accounted for 11%. The most systematic transitions in terms of gain were from shrubland to farmland, alluvial deposit to settlement, and alluvial deposit to active channel and settlement. Most of these transitions were related to the river dynamics and depict cyclic transitions: farmland → active channel → alluvial deposits → grassland/shrubland → farmland. Human interventions and natural vegetation succession were also very important. The study concludes that river systems have considerable impact on livelihood and need attention in land management undertakings in graben bottoms.