Habitat selection and diet of Great Snipe Gallinago media during breeding

The Great Snipe Gallinago media is considered to be an endangered species. This paper examines its food and habitat use on a sub-alpine/low-alpine breeding area in central Norway. It was estimated that earthworms constitute more than 90% of Great Snipe food (by weight). Feeding birds selected the low herb willow scrub vegetation community and to a lesser degree eutrophic fen. Birds did not selectively feed on eutrophic dwarf birch/juniper heath despite it being the third most used vegetation community by virtue of its extent. Although soil penetrability, vegetation cover and earthworm density varied across vegetation communities, Great Snipe selected sites with similar habitat characteristics in different vegetation communities. Great Snipe seemed to select for an optimal combination of soil penetrability and earthworm density, and for medium scrub cover. Nests were found in a broad range of vegetation communities, but only low herb willow scrub was selectively used. However, an equal number of nests was found in eutrophic fen due to its larger extent. Dense vegetation cover around nests and short flushing distance of incubating females indicate low sensitivity to disturbance. We consider the Great Snipe to be a food and habitat specialist, requiring habitats rich in sub-surface invertebrates to breed. This may explain its scattered distribution in Scandinavia, and may render it vulnerable to habitat modification and loss.     

Growth of reindeer lichens and effects of reindeer grazing on ground cover vegetation in a Scots pine forest and a subarctic heathland in Finnish Lapland

Reindeer lichens are an important component of northern ecosystems. The aim of this study was to measure the growth rate of terricolous lichens as it is a key parameter involved in productivity of these ecosystems and an important part of lichen tolerance to reindeer grazing. Furthermore, the natural succession and the long-term effects of reindeer grazing on lichen community characteristics in two contrasting habitats were investigated as well as the interactions between lichen cover and mosses and vascular plants. Biomass and coverage measurements were conducted in a lichen woodland and in a subarctic heath with grazed and ungrazed areas in northern Finland. Measurements spanning over 13 yr of undisturbed development show that the growth rate of Cladina stellaris can be as high as >0.17 g g⁻¹ produced annually, although in average growth rates were much lower. During the succession of ground vegetation, C. stellaris , C. rangiferina , C. mitis and Cetraria nivalis increased in biomass in fenced areas and were reduced most in biomass by reindeer in unprotected areas. Reindeer grazing and trampling seem to change the vegetation towards a type that is dominated by small dwarf shrubs, bare soil and minute-cup lichens ( Cladonia spp.). Removing the lichen layer by reindeer may reduce natural regeneration of pine trees as implied by increasing numbers of pine seedlings with increasing lichen cover.     

PHOTOSYNTHESIS AND RESPIRATION OF ALPINE LICHENS

Photosynthetic and respiratory rates were studied in Cetraria islandica, C. nivalis, and Cladonia rangiferina in the alpine zone of Mt. Washington, New Hampshire. Measurements were made in the field using an infrared gas analyzer; light, temperature, and thallus water content were varied. In all species, considerable reduction in photosynthesis and respiration occurred with drying, more rapidly in photosynthesis than respiration. Optimal photosynthetic rates in all 3 species occurred at 15–20 C with light levels of 1,600 ft-c. Light compensation points ranged from 200 to 350 ft-c. Optimal respiratory rates were attained at 15 C in the 2 species of Cetraria and at 20 C in Cladonia. The data indicate that these wide-ranging, arctic-alpine and arctic-temperate lichens on Mt. Washington are quite well adapted to a moist, foggy environment with cool temperatures and low light levels, conditions which predominate in summer.     

阿尔泰山两河源自然保护区地面生地衣群落物种分布特征

用聚类分析和主成分分析法对阿尔泰山两河源自然保护区地面生地衣群落进行划分;根据优势地衣种类进行群落命名。应用典范对应分析法探讨了地面生地衣种类分布与环境间的关系。结果表明:阿尔泰山两河源自然保护区地面生地衣可分为以下4个群落:白腹地卷+硫石蕊+喇叭粉石蕊群落;茸珊瑚枝+长根地卷+黑瘿地卷群落;土星猫耳衣+软鹿蕊+膜地卷群落;雪岛衣+北方石蕊+绿皮地卷群落。各群落中的地面生地衣种类与盖度,在一定程度上反映了地面生地衣在阿尔泰山两河源保护区分布格局与环境的关系。典范对应分析结果表明,阿尔泰山地面生地衣群落物种分布受到土壤湿度、土壤pH、海拔高度、林冠层郁闭度和灌木层盖度等环境因素的影响,其中海拔、土壤湿度、林冠层郁闭度等对地衣物种分布的影响最大。     

Prevalence of nest predators in a sub-Arctic ecosystem

High nest loss is an important driver of gallinaceous bird population dynamics. Identifying factors determining the spatial distribution of potential nest predators and thereby indirectly risk of nest losses is therefore essential. The aim of this 1-year study was to estimate relative predation rates on artificial ground nests in willow ptarmigan (Lagopus lagopus) habitats, along replicate altitudinal gradients (transects, n?=?60) spanning from sub-Arctic birch forest to the low-alpine tundra in three locations in northern Norway. In each transect, one artificial nest (track board) was placed in three different habitats: (1) birch forest, (2) edge between birch forest and low-alpine tundra and (3) low-alpine tundra. Total predation rates over all habitats within locations ranged from 47.4% to 77.5% and did not vary systematically in space and time. The average predation rate by avian predators was consistently high (58%), and mammalian predation rate was consistently low (5.6%). The consistently high level of predation inflicted by birds was mainly due to omnipresent corvids, especially the hooded crow (Corvus cornix). Analysis of species-specific predation rates showed that habitat and location effects were insignificant for all species, except for raven (Corvus corax) that showed clearly higher predation in one of the locations. The results indicate that from the perspective of the spatial distribution of potential nest predators in sub-Arctic birch forest, ground nesting birds like willow ptarmigan should not be expected to be selective with respect to nesting habitat in the ecotone between birch forest and the low-alpine tundra.     

Succession in a New Zealand alpine cushion community: a Markovian model

A permanent plot in a low-alpine cushion/tussock/shrub community was mapped at ca. decade intervals from 1953 to 1984. Transition probabilities between vegetation types were calculated, and a Markovian model was fitted.In spite of non-stationarity a Markov model was consistent with the observations, and produced reasonable predictions, especially for the major components of the vegetation. The model predictions were conservative in terms of future changes, in that future changes would be smaller than those observed, but such predictions could be supported by independent evidence, such as the nature of the non-stationarity, plant counts and seedling numbers.The general pattern was of a decrease in the cover of both Chionochloa rigida tussocks and mixed turf, and an increase in the cover of cushion bog species, especially Donatia novae-zelandiae. Shrubs, the suggested climax, showed no tendency to increase. Known climatic changes cannot explain the trend, which therefore seems to be a local retrogressive succession. There may be a cycle of alternating cushion and turf.     

Effects of 17-α-estradiol on a free-living marine nematode community: a microcosm experiment

A microcosm experiment was used to examine the effects of 17-α-estradiol on a nematode community. Four 17-α-estradiol concentrations (0.15, 0.31, 0.62 and 1.24 ppm) were tested, and effects were examined after 30 days. Significant differences were noted between nematode assemblages from the control and those from 17-α-estradiol treatments. Total nematode abundance, Shannon–Wiener index and evenness were affected by 17-α-estradiol contamination, but species richness was unaffected. Chromadorina metulata and Ascolaimus elongatus were eliminated at all doses tested and seemed to be intolerant to estradiol. Kraspedonema octogoniata decreased at all doses and could be categorised as sensitive to estradiol contamination. Spirinia gerlachi increased at all doses tested and seemed to be an opportunistic species at the doses tested.     

Effects of plant species richness on stand structure and productivity

Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments. Little is known about the direct mechanisms that cause this result. We tested if by occupying different heights and depths above and below ground, and by optimizing the vertical distribution of leaf nitrogen, species in mixtures can contribute to increased resource uptake and, thus, increased productivity of the community in comparison with monocultures.Methods We grew 24 grassland plant species, grouped into four nonoverlapping species pools, in monoculture and 3- and 6-species mixture in spatially heterogeneous and uniform soil nutrient conditions. Layered harvests of above- and belowground biomass, as well as leaf nitrogen and light measurements, were taken to assess vertical canopy and root space structure.Important findings The distribution of leaf mass was shifted toward greater heights and light absorption was correspondingly enhanced in mixtures. However, only some mixtures had leaf nitrogen concentration profiles predicted to optimize whole-community carbon gain, whereas in other mixtures species seemed to behave more 'selfish'. Nevertheless, even in these communities, biomass production increased with species richness. The distribution of root biomass below ground did not change from monocultures to three- and six-species mixtures and there was also no indication that mixtures were better than monocultures at extracting heterogeneously as compared to homogeneously distributed soil resources. We conclude that positive biodiversity effect on aboveground biomass production cannot easily be explained by a single or few common mechanisms of differential space use. Rather, it seems that mechanisms vary with the particular set of species combined in a community.     

Cladonia krogiana,a new xanthone-containing species from Norway

Abstract:The new lichen species Cladonia krogiana is described from eight localities in SE Norway. It resembles C. polycarpoides morphologically, but differs in containing barbatic acid and chlorovinetorin.     

新疆天山西部山脉森林生态系统地衣群落结构的初步研究

 根据多年的研究资料并采用聚类分析方法对分布在天山西部山脉的地衣群落结构进行了研究。结果表明,分布在该地区的地衣种类形成了6种群落:1) 土星猫耳衣（Leptogium saturninum)＋矮石蕊(Cladonia humilis)＋兰灰蜈蚣衣（Physcia caesia）群落;2）黑穗石蕊（Cladonia amaurocr     

Water-soluble phenolic compounds in lichens

The quantity and the qualitative composition (for some species) of phenolic compounds (PC) washed out of the intact thalli of lichens of the orders Peltigerales (the genera Peltigera, Solorina, and Nephroma) and Lecanorales (the genera Cladonia, Alectoria, and Cetraria) were studied. It was shown that the quantity of leachable PCs in Peltigerales was on average 2–3 times higher than in Lecanorales. At the same time, the extractability of PC from intact thalli by water was higher in Lecanorales than in Peltigerales: 48–88% and 34–70%, respectively, of the PC content in ethanol extracts from crushed thalli (i.e., of the total content of soluble PC). Water-soluble PC in the lichens Peltigera aphthosa, Solorina crocea, Cetraria islandica, Flavocetraria nivalis, Cladonia uncialis, and Cladonia arbuscula were represented by 7–12 phenolic compounds with similar qualitative composition in the species of the same order. The most part of water soluble PC were phenylpropanoids. All of the studied species showed the presence of p-hydroxybenzoic acid derivatives; vanillic and protocatechuic acid derivatives were found in Cetraria and Cladonia species, respectively.     

Behaviour and resource use of two competing vole species under shared predation risk

Indirect interaction between two competing species via a shared predator may be an important determinant of population and community dynamics. We studied the effect of predation risk imposed by the least weasel Mustela nivalis nivalis on space use, foraging and activity of two competing vole species, the grey-sided vole Myodes rufocanus, and the bank vole Myodes glareolus. The experiment was conducted in a large indoor arena, consisting of microhabitat structures providing food, shelter, trees for refuge and separated areas with high and low predation risk. Voles were followed for 5 days: 2 days before, 1 day during and 2 days after the presence of weasel. Our results suggest an effect of weasel presence on the vole community. Voles of both species shifted their activity from risky to less risky areas, climbed trees more often and were less active. Seed consumption was not affected by weasel presence. The time spent in the risky and less risky area did not differ between species, but bank voles spent more time in trees than grey-sided voles. Males of both species were more exposed to predation risk than females, i.e. generally spent more time in the risky area. Proportion of time spent in the risky area, the use of area, trees and food stations were sex dependent. Activity and use of trees were species dependent. We found no evidence for despotic distribution between our two species, although bank voles seemed to be more affected by coexistence, since they lost weight during the experiment. Based on our results we conclude that predator response was largely similar between species, while the sex-specific responses dominated. Besides a stronger escape response in the bank vole, the strongest individual differences were sex specific, i.e. males were more prone to take risks in space use and activity.     

Nutritive value of terricolous lichens for reindeer in winter

Abstract:In contrast to virtually all other species of ruminants, reindeer (Rangifer tarandus) eat substantial amounts of lichens in winter. Several different species of lichens are eaten and most are highly palatable. The chemical composition and the in vitro digestibility of six species of terricolous lichens commonly eaten by reindeer were measured. Ruminal inoculum was obtained in winter from six free-ranging reindeer that had been grazing on natural pastures in northern Norway. Analysis of the plant parts recovered from their rumens confirmed that the animals had been eating a mixed diet that included both lichens and vascular plants. The chemical composition and the in vitro digestibility of the different species of lichens varied considerably between species and genera. Cetraria islandica, C. nivalis andCladonia arbuscula were highly digestible [69–77% dry matter (DM)], Stereocaulon paschale was poorly digestible (43% DM), whereas Cladonia stellaris and C. gracilis had an intermediate digestibility (56–57% DM). Mixing Cladonia stellaris with vascular plants (50:50) had no effect on the in vitro digestibility of the combined substrates. The in vitro digestibility of Cladonia stellaris in inoculum from two captive reindeer which had had no access to lichens was very low (10% DM). This shows that the source of inoculum used for digestibility trials has a major effect on the apparent digestibility of the substrates. Evidently, the extent to which reindeer are able to utilize lichens depends on the species that are selected and on what the animals have been eating recently.     

Local population subdivision in the lichen Cladonia subcervicornis as revealed by mitochondrial cytochrome oxidase subunit 1 intron sequences

A 753-771 bp long intronic sequence from the mitochondrial cox 1 gene of Cladonia subcervicornis (Cladoniaceae, Lecanorales, Ascomycota) was amplified with newly designed PCR primers. The cox 1 intron sequence, which apparently has not been used for phylogenetic or population genetic research in fungi, displays high infraspecific variation. Sequences were obtained from 124 specimens from four neighboring localities in coastal Hordaland, western Norway. An exact test of population differentiation and population pairwise fixation indices F(ST) show significantly reduced gene flow between the northernmost locality and the other three populations. Although Cladonia subcervicornis frequently produces apothecia, we conclude that dispersal by ascospores over long distances is rather ineffective in this species.     

The Effect of Nitrogen and Glyphosate on Survival and Colonisation of Perennial Grass Species in an Agro-Ecosystem: Does the Relative Importance of Survival Decrease with Competitive Ability?

The ecological success of a plant species is typically described by the observed change in plant abundance or cover, but in order to more fully understand the fundamental plant ecological processes, it is necessary to inspect the underlying processes of survival and colonization and how they are affected by environmental conditions. A general ecological hypothesis on the effect of environmental gradients on demographic parameters is proposed and tested. The hypothesis is that decreasing fitness or competitive ability along an environmental gradient is associated with an increasing importance of survival for regulating the abundance of the species. The tested hypothesis is related to both the stress gradient hypothesis and whether the importance of competition increases along productivity gradients. The combined effect of nitrogen and glyphosate on the survival and colonization probability of two perennial grass species, Festuca ovina and Agrostis capillaris, which are known to differ in their responses to both glyphosate and nitrogen treatments, is calculated using pin-point cover data in permanent frames. We found that the relative importance of survival increased with the level of glyphosate for the glyphosate sensitive A. capillaris and decreased for the glyphosate tolerant F. ovina. Likewise, increasing levels of nitrogen increased the importance of survival for the relative nitrophobic F. ovina. Consequently, the proposed hypothesis was corroborated in this specific study. The proposed method will enable predictions of the effects of agricultural practices on community dynamics in a relatively simple setup eliminating the need to quantify all the interaction among the species in the plant community. The method will be immediately useful for the regulation of non-cultivated buffer strips between agricultural fields and semi-natural and natural biotopes such as hedgerows and waterways.     

Responses to natural climatic variation and experimental warming in two tundra plant species with contrasting life forms: Cassiope tetragona and Ranunculus nivalis

Two circumpolar tundra plant species, the evergreen dwarfshrub Cassiope tetragona and the perennial herb Ranunculus nivalis , were studied at Latnjajaure in northern Swedish Lapland during three consecutive growing seasons (1993–95) as a contribution to the ITEX programme. Open-top chambers (OTCs) were used in a passive heating experiment, and the performance of the plants in unmanipulated controls was correlated with climatic fluctuations among the years. Phenological, vegetative, and reproductive variables were measured. In both species phenological responses were controlled mainly by ambient air temperature. In the evergreen C. tetragona vegetative growth was controlled mainly by the influx of global solar radiation and was not temperature-dependent, whereas the opposite applied in the herbaceous R. nivalis . Vegetative growth in C. tetragona was rather stable among years as well as between treatments, whereas it was strongly influenced by annual climate in R. nivalis . Both species increased their reproductive success with increasing temperature, but R. nivalis was also radiation-dependent in this case, probably because of its green, photosynthetic nutlets. Ovule number in R. nivalis increased steadily in the experimentally heated plots during the study in response to the constant temperature amelioration above the ambient. At the community level, evergreen C. tetragona seems to have low competitive ability under warmer conditions. The situation for vernal low-growing herbs like R. nivalis is more complex; despite a strong positive response to increased temperature, they may exhibit decreased reproductive success if overgrown by a vigorous graminoid canopy.     

Litter legacy after spruce plantation removal hampers initial vegetation establishment

Restoration of areas used for intensive even-aged Norway spruce (Picea abies Karst.) plantations often involves felling and subsequent spontaneous vegetation succession. However, the accumulated litter layer may hamper vegetation development, and thereby postpone recovery or even change the outcome.We studied effects of the litter layer on vegetation establishment during two seasons following a clear-cut of Norway spruce in Denmark. We experimentally assessed the response of multiple vegetation properties to litter removal, with and without wildlife exclusion by fencing, and in combination with sowing of trees, while fencing. Burning was tested as an alternative way to remove the litter layer.Vegetation establishment was poor, when the litter layer was intact, and cover developed slowly remaining below 10% after two years, irrespective of fencing. In contrast, litter removal and fencing together gave significantly faster recovery and reached nearly 60% mean cover. Vegetation cover was driven by few dominant species, especially the sedge Carex pilulifera. Species richness was similar in all treatments, but increased with sowing of trees. Fencing resulted in taller birch seedlings independently of litter removal, but enhanced by seedling density. Litter removal seemed to favor species with lighter seeds, lower specific leaf area (SLA) and lower Ellenberg N value, i.e. associated with relative infertile conditions. Disturbing the litter by burning seemed to have an effect comparable to mechanical removal, and could be a management alternative.Our results showed that a persistent litter layer after spruce plantation removal may hamper the initial vegetation establishment. Actively removing litter may serve as an additional restoration intervention to overcome this legacy. However, as grazing can keep this potential in check, wildlife exclusion may be necessary as well. To speed up recovery and diversify vegetation structure after spruce plantation removal, we suggest patchy disturbance of the litter, essentially combined with wildlife exclusion.     

Competitive displacement or biotic resistance? Disentangling relationships between community diversity and invasion success of tall herbs and shrubs

Questions: Are negative invasion–diversity relationships due to biotic resistance of the invaded plant community or to post‐invasion displacement of less competitive species? Do invasion–diversity relationships change with habitat type or resident traits? Location/species: Lowlands and uplands of western and southern Germany, Heracleum mantegazzianum; mountain range in central Germany, Lupinus polyphyllus; and coastal dunes of northwest Germany, Rosa rugosa. Methods: We tested the significance and estimated regression slopes of invasion–diversity relationships using generalized linear (mixed effects) models relating invader cover and habitat type to species richness in different plant groups, stratified based on size, life cycle and community association. Results: We found negative, positive and neutral relationships between invader cover and species richness. There were negative linear correlations of invader cover with small plant species throughout, but no negative linear correlation with tall species. Invasion–diversity relationships tended to be more negative in early‐successional habitats, such as dunes or abandoned grasslands, than in late‐successional habitats. Conclusions: Invasion diversity–relationships are complex; they vary among habitat types and among different groups of resident species. Negative invasion–diversity relationships are due to asymmetric competitive displacement of inferior species and not due to biotic resistance. Small species are displaced in early‐successional habitats, while there is little effect on persistence of tall species.     

Ecoregions within the Brazilian Pampa biome reflected in Odonata species assemblies

Based on vegetation composition, previous studies of the Pampa biome in southern Brazil have defined seven ecoregions within the area. Here, we test this ecoregion approach studying the semi‐aquatic insect group Odonata in five of these regions, aiming at comparing the ecoregions to the more traditional environmental predictors of water quality and land cover. Based on a data set of occupancy comprising 99 species distributed between 131 localities, a one‐way Permutational Multivariate Analysis of Variance was used to compare differences in the species composition between the ecoregions, followed by a Principal Component Analysis to visualize the variation. The composition varied significantly between all groups tested, and the ordination explained 61.8% of the variance. A partial redundancy analysis of ecoregions, land cover and water quality variables explained 71% of the variance in Odonata community structure. Ecoregion was the most important predictor, followed by water quality and land cover. Within these species assemblies, we could select certain species that were representative of a given ecoregion, to which their distribution within the Pampa biome was entirely or mainly confined. Of 24 representative species 41.7% were rare, while the rest were more abundant and, hence, easier to detect. We suspect that the differences found between the Pampa ecoregions might be due to geology, as such factors may be strong determinants of biodiversity. Specific ecological requirements at the family and genus levels also seemed to act selectively on the species compositions within the ecoregions. Today, the Pampa is highly fragmented due to agricultural activities such as rice cultivation, extensive cattle farming and forest plantations. We suggest that an ecoregion‐based approach to the implementation of conservation measures may be the best way to help these distinct species assemblies survive.     

Breeding systems in the lichen-forming fungal genus Cladonia

The breeding systems of three species of the lichen-forming fungal genus Cladonia were investigated. Cladonia floerkeana, Cladonia galindezii, and Cladonia portentosa were selected due to their contrasting ecologies and reproductive strategies, and because they belong to the Lecanorales, the major lichen-forming order. Sibling single-spore progeny were collected from apothecia and used to establish axenic cultures. Two experimental approaches were used to determine breeding systems. First, RAPD-PCR and AFLP fingerprinting revealed that spores from the same apothecium were not genetically uniform, indicating heterothallism in each of these species. Second, segregation of a MAT-2 mating-type gene was assessed using degenerate PCR primers designed to amplify the high-mobility group region. A MAT-2 gene occurred in 40-60% of progeny, consistent with a heterothallic breeding system. The PCR product from C. galindezii was cloned and sequenced, and confirmed to have the characteristic motifs of a MAT-2 HMG gene. This is thought to be the first report of the use of segregation of a mating-type gene among ascospore progeny to determine the breeding system of a fungal species. The ecological significance of the results is discussed.