Climate change was already shown to increase species numbers in high elevations. In contrast, grazing might interfere with climate change effects. To disentangle both the effects remains a major ...challenge of alpine ecology. The present study investigated both the effects on species diversity along an elevation gradient in the Austrian Central Alps. We aimed to answer the following questions: How do species diversity and frequency of subalpine–alpine–subnival plant communities change in grazed sites with time? Do competitive plant species increase in the communities? How does grazing exclusion affect species diversity, functional groups, and strategy types? Are environmental changes (temperature, sunshine duration, precipitation) responsible for diversity changes or does grazing override climate effects? The study was carried out for 18 years along an elevation gradient from 1,958 to 2,778 m a.s.l. at Obergurgl (Tyrol, Austria), including six different plant communities. A total of 11 grazing exclusions were established. At each community, the frequency of the species was counted in 1 m
2
plots yearly or at least every 3–4 years. Environmental data were obtained from the weather station Obergurgl. Changes of the community parameters and the species composition were analyzed by partial redundancy analyses and mixed-effect models. Species diversity increased with time at all grazed sites, but this increase was suppressed under grazing exclusion. Grazing exclusion effects became pronounced after 5 years. The most consistent result was the increase of bryophytes throughout. At the subalpine grassland, tall-growing species expanded in the exclosures; at the upper alpine
Carex curvula
grassland, snow bed species decreased with grazing exclusion. Among the environmental factors, sunshine duration of the previous year’s autumn quartal was found to be the essential variable for the changes. We concluded that diversity increases in grazed communities of the Austrian Central Alps can be attributed to climate change. An indication of slightly reduced and altered weather effects under grazing exclusion was found.
As glaciers retreat, their forelands represent “natural laboratories” for the study of primary succession. This review describes how certain arthropods conquer pristine ground and develop food webs ...before the establishment of vascular plants. Based on soil samples, pitfall traps, fallout and sticky traps, gut content studies, and some unpublished data, we compare early arthropod succession on glacial forelands of northern Europe (Iceland, Norway including Svalbard, and Sweden) and of the Alps (Austria, Italy). While macroarthropod predators like ground beetles (Coleoptera: Carabidae), harvestmen (Arachnida: Opiliones), and spiders (Arachnida: Araneae) have usually been considered as pioneers, assumed to feed on airborne prey, this review explains a different pattern. Here, we highlight that springtails (Collembola), probably feeding on biofilm made up of algae or cyanobacteria, are super-pioneers, even at high altitudes and under arctic conditions. We also point out that macroarthropod predators can use locally available prey, such as springtails or non-biting midges (Diptera: Chironomidae). Pioneer arthropod communities vary under different biogeographical and climatic conditions. Two pioneer food webs, from northern Europe and the Alps, respectively, differed in structure and function. However, certain genera and orders were common to both. Generalists and specialists live together in a pioneer community. Cold-adapted specialists are threatened by glacier melting.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Climate change is disproportionately impacting mountain ecosystems, leading to large reductions in winter snow cover, earlier spring snowmelt and widespread shrub expansion into alpine grasslands. ...Yet, the combined effects of shrub expansion and changing snow conditions on abiotic and biotic soil properties remains poorly understood. We used complementary field experiments to show that reduced snow cover and earlier snowmelt have effects on soil microbial communities and functioning that persist into summer. However, ericaceous shrub expansion modulates a number of these impacts and has stronger belowground effects than changing snow conditions. Ericaceous shrub expansion did not alter snow depth or snowmelt timing but did increase the abundance of ericoid mycorrhizal fungi and oligotrophic bacteria, which was linked to decreased soil respiration and nitrogen availability. Our findings suggest that changing winter snow conditions have cross‐seasonal impacts on soil properties, but shifts in vegetation can modulate belowground effects of future alpine climate change.
Climate change is disproportionately impacting mountain ecosystems, leading to large reductions in winter snow cover, earlier spring snowmelt and widespread shrub expansion into alpine grasslands. Using complimentary field experiments, we show that earlier snowmelt and reductions in snow cover have cross‐seasonal impacts on soil microbial communities and their functioning, with consequences for soil nutrient pools and fluxes. However, we also show that shifts in vegetation can modulate the belowground effects of future alpine climate change.
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•Temperature determines structure and active pathways of the methanogenic community.•Highest methane yields and substrate utilization efficiency were found at 45 °C.•Slightly longer ...lag-phase at 45 °C due to physiological adaptation of microbiota.•At 45 °C, bacterial community composition is closer to that at 55 °C than at 37 °C.•Unheated AD is profitable at ambient temperatures ≥20 °C due to high CH4 contents.
Throwing longstanding habits over the pile may be necessary to improve biogas production, in particular when it comes to the process temperature. Its effect on biogas production was investigated with lab-scale reactors operated in fed-batch mode (cattle slurry and maize straw) at 10–55 °C over six months. Biochemical and microbial changes were comprehensively investigated. Production was highest and most efficient at 45 °C with an average methane yield of 166 NL kg−1 VS, and thus 12.8% and 9.6% higher than at 37 and 55 °C. Temperature significantly affected the microbiota and higher temperature provoked a shift from Bacteroidetes/Proteobacteria to Firmicutes. A transition from hydrogenotrophic to acetoclastic methanogenesis was observed from 10 to 45 °C, while the trend was reversed at 55 °C. The results contest the textbook notion of preferred and most efficient temperatures for AD and suggest reconsideration of the temperature range around 45 °C for efficient manure-based co-fermentation.
To understand soil food webs, empirically generated data on the trophic connections and the feeding ecology of the major below-ground animal taxa are needed. Here we used stable isotope analysis to ...assess the trophic ecology of wireworms, the larvae of click beetles, in Central European arable land. Wireworms are amongst the major soil macroinvertebrates and are of practical importance in arable soils. Besides feeding on crops, they are thought to feed on weeds, soil organic matter (SOM), and even animal prey, but their feeding ecology is poorly studied under natural conditions. Elaterid larvae and their putative feeding substrates—plant roots, SOM, and litter—were sampled at 17 locations in Austria, Germany, and Italy and their isotope ratios of carbon (
12C/
13C) and nitrogen (
14N/
15N) measured to determine the wireworms’ trophic level, the importance of SOM and weeds within the diet of
Agriotes larvae, as well as the individual diet variation in
Agriotes obscurus larvae.
δ
15N signatures suggested that
Agriotes larvae are predominately herbivorous, whereas the other wireworm species primarily fed on animal prey. In contrast to SOM, weeds were readily eaten by
Agriotes larvae: their dietary contribution ranged between 28% and 67% in weedy maize fields. Most
A. obscurus larvae fed on a mixed diet of weeds and maize, although ∼15% of the larvae fed primarily on one of the two food sources only.
δ
15N signatures indicated that ∼10% of the “herbivorous”
A. obscurus larvae fed primarily on animal prey, revealing high intraspecific trophic plasticity in these soil insects. Wireworm feeding behaviour is apparently complex at the individual level: the population consists of types A and B generalists, a phenomenon which needs further assessment.
On a glacier foreland of the Central Austrian Alps, a permanent plot study was performed to investigate the successional pathway on two moraines. We expected that the pioneer stage deglaciated for ...25 years will converge to an early successional stage after another 25 years and the early stage deglaciated for 40 years will show trends toward a late successional stage. Different dynamics of species occurrence such as colonization/persistence and cover increase/decrease, were anticipated. Twenty plots of 25 × 25 cm were established in 1996 on each successional stage by selecting vegetated and bare ground plots to account for impacts of facilitation on seedling recruitment. We expected seed and establishment limitations, therefore, also effects of sowing were studied on sown and control plots. Species enrichment occurred on all control and sown plots of both stages. However, the pioneer stage did not converge to an early successional stage as it was expected. On the early successional stage, only on sown plots a development toward a late successional stage was found. Bryophyta were the most efficient colonizers on all plots together with the lichen
Stereocaulon alpinum
at the pioneer stage and the sown species
Anthyllis vulneraria
ssp.
alpicola
at the early successional stage. The pioneer species
Saxifraga oppositifolia
was still present after 25 years on the pioneer and early successional stages, although its cover significantly decreased. We conclude that seed and establishment limitations, drought, facilitation deficits, and ageing of individuals are the essential drivers on the studied glacier foreland, creating ‘quasi-stationary’ communities.
The increasing efflux on a large scale of organic contaminants holding endocrine disrupting activity from sewage treatment plants produces detrimental biological effects to various fish species. ...However, the impact of small-scale sewage treatment plant-efflux in small river streams and narrow creeks is largely unknown. Extensive pesticide output especially in vineyards and orchards also causes adverse effects on the endocrine system of wildlife fish species inhabiting nearby rivers. To elaborate whether fish species and populations in the areas of interest were at risk of experiencing endocrine disruption, we identified different biomarkers related to endocrine disruption in
Cottus gobio
and
Salmo trutta
fario and applied this approach to selected Austrian freshwater streams pre and post sewage treatment plants and permanent cultures with extensive pesticide output in South Tyrol. Overall, mRNA expression levels of vitellogenin, estrogen receptor
α
and zona pellucida genes in wildlife fish, compared to a control population reared under constant conditions in the laboratory were significantly increased. Sewage-treatment plant efflux did not significantly affect the mRNA expression levels while extensive use of pesticides altered mRNA expression significantly in
C. gobio
.
C. gobio
and
S. trutta
fario display different levels of mRNA expression. Cadmium and copper concentrations in liver tissues varied but did not indicate significant levels of contamination. Our results demonstrate the presence of endocrine disrupting chemicals in the tested freshwater streams. We anticipate our study to be a starting point for further studies focusing on the effects of endocrine disrupting chemicals on individuals and populations. Especially the fact that the two selected species reveal highly different levels of mRNA expression levels is of interest when applying biomarker approaches which can be a useful tool for monitoring projects and risk-assessment associated studies.
Since there is little known about invertebrates in glacier foreland succession, the aim of this study was (1) to characterize succession patterns of the epigean fauna, (2) to analyze how these are ...related to plant succession, and (3) to investigate the influence of locally varying environmental conditions. The Central Alpine glacier foreland of the Rotmoostal (Obergurgl, Tyrol, Austria) was selected as an example situated above the treeline (2280-2450 m above sea level) where a 2 km long deglaciated area covers a chronosequence of 140 yr. The epigean fauna was sampled in 70 plots of all ages and in nearby sites outside the foreland by pitfall trapping over the entire growing season in 1996 (June-October). Abiotic characterization and vegetation recordings were available for all plots. Rapid development of pioneer communities over 50 yr was followed by little change in older stages. Further development towards the mature invertebrate communities characteristic of areas outside the foreland only occurred on the sunny slopes near the terminal moraine and proceeded in a qualitatively different way. Sites in the alluvial outwash plain or otherwise physically disturbed were clearly successionally younger than adjacent undisturbed sites. The first colonizers were almost exclusively predators. Herbivores and decomposers appeared later. Similarities and differences between faunal and floral succession patterns are discussed. The major factors affecting faunal succession as identified by canonical correspondence analysis were soil formation and vegetation development along the chronosequence. In addition, favorable sun and light conditions may facilitate successional progress. Fauna communities also react to local conditions, most notably to the moisture/snow cover regime. Abiotic environment, architecture of plants, and plant species composition interact strongly as explanatory factors, but all three aspects also contribute significant unique correlations. There were no hints of random colonization patterns at the youngest sites. Pioneer invertebrate communities had the same small-scale spatial heterogeneity and equally strong correlations with environmental conditions as did the well-established communities at older sites. This leads to the conclusion that faunal colonization and succession in Alpine glacier forelands, to a large extent, follow predictable and deterministic assembly rules and that stochastic effects are of minor importance.
Substrate spectra for anaerobic digestion have been broadened in the past decade, inter alia, due to the application of different pretreatment strategies and now include materials rich in ...lignocellulose, protein, and/or fat. The application of these substrates, however, also entails risks regarding the formation of undesired by-products, among which phenolic compounds are known to accumulate under unfavorable digestion conditions.
Different states of overload were simulated in batch experiments while reviewing the generation of phenyl acids out of different lab-use substrates in order to evaluate the impact on biogas and methane production as well as some additional process performance parameters under defined laboratory conditions. Investigations were conducted under both mesophilic and thermophilic conditions.
It could be shown that the tested input materials led to the formation of phenyl acids in a substrate-dependent manner with the formation itself being less temperature driven. Once formed, the formation of phenyl acids turned out to be a reversible process.
Although a mandatory negative impact of phenyl acids per se on the anaerobic digestion process in general and the methanogenesis process in particular could not be proven, phenyl acids, however, seem to play an important role in the microbial response to overloaded biogas systems.
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