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排序方式: 共有60条查询结果,搜索用时 15 毫秒
1.
Alberto Doretto Francesca Bona Elisa Falasco Daniele Morandini Elena Piano Stefano Fenoglio 《河流研究与利用》2020,36(1):91-101
Droughts are affecting an increasing number of lotic ecosystems worldwide due to the combined effects of climatic and anthropogenic pressures. Unlike naturally intermittent rivers, where the drying phase is a part of the annual flow regime, water scarcity in Alpine rivers represents a relatively recent phenomenon and, therefore, a major threat for the biodiversity of these lotic ecosystems. However, Alpine stream community response to drought is still poorly investigated. Here, we assess the recovery of macroinvertebrates in two Alpine streams after a supraseasonal drought. As water returned, a total of 10 sampling sessions were carried out, and temporal patterns in diversity, density, and taxonomic composition of benthic communities, as well as in the percentage of functional feeding groups, were investigated. We found that the resistance of invertebrate communities in Alpine streams is generally low: drought markedly reduced the diversity and density of macroinvertebrates. Conversely, our results suggest that the passive dispersal by drift from the upstream river sections seems the most probable mechanism promoting the post‐drought recovery. Nevertheless, this resilience ability appears to be stream specific and influenced by intrinsic stream characteristics, including the flow permanence and distance from the nearest upstream perennial reach. This work sheds light on the ecological consequences of droughts on macroinvertebrate communities. As flow intermittency in Alpine areas is expected to intensify under current global change scenarios, results of this study provide important information to predict changes in the taxonomic composition and diversity of macroinvertebrate communities. 相似文献
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Seyhun Yurdugül 《International Journal of Food Science & Technology》2008,43(5):865-870
Alpine strawberries (Fragaria vesca) are used in fruit juice, marmalade, or jam production and as a result have economical importance in food sector. The fresh alpine strawberries have a tendency to lose their quality in a few days as a result of high water loss and spoilage. In this paper, the results of a study on the effects of freeze drying process on the characteristics of the alpine strawberries, such as firmness, sugar content, pH, colour, weight loss, dissolved solids, anthocyanin and vitamin C content with reference to the fresh, are reported. Freeze‐drying indicated no difference in the characteristics of the alpine strawberries when compared with the fresh. It is found that a slight acid or base addition onto the rehydrated alpine strawberry juice preserved the stability of pigments and the colour. In addition, the rehydrated alpine strawberry juice exhibited an antimicrobial activity towards an important foodborne pathogen, Enterobacter faecium ATCC 6057. 相似文献
4.
Elizabeth Cronin 《History of Photography》2013,37(3):248-259
This article examines the Austrian Homeland or Heimat movement through an investigation of Wilhelm Angerer's 1942 book of poems and photographs, A Song Sweeps Down from the Mountains (Ein Lied rauscht von den Bergen). The multifaceted, widespread regionalist or homeland movement infiltrated all areas of visual culture, from tourist postcards and popular films to high‐quality picture books and exhibition prints. In considering the book by Angerer, this article highlights an intersection of modernity with tradition, defined in terms of a popular visual culture that formed a distinct and complex concept of the Austrian Heimat. 相似文献
5.
Most of the alpine tundra lakes, of average size 8,500 m2, are widely spread in the Beiluhe Basin on the Qing-Tibet Plateau, where ice-rich permafrost exists. Approximately 70% of the lakes are elliptical in shape and 15% are elongated. About 80% of the lakes are unfrozen to the bottom throughout the year while a larger portion of it, about 60%, may be underlain by taliks that penetrate permafrost. The BLH-A Lake, a representative lake with 2-m deep water in the region, has been observed for about four years (from 2006 to 2009). Ice starts to cover on the lake-surface after mid-October, and its thickness increases to 60 to 70 cm by the end of cold season. The ice cover then starts to melt in later April and melts completely around mid-May. The lake-surface temperatures change sinusoidally with the air temperatures, but lagging about half a month. The water warms with the increase of the water depth, and the maximum annual temperature appears at depth of 1.5 m with a value of 14.3 °C on July 30, 2007. The lake-bottom temperatures are not isothermal at different depths for most time of a year. It may be related to the variable climate, little snow, and intensive solar radiation. The mean annual lake-bottom temperatures are about 5.5 °C in the deep pool with 2 m deep water and 4.3 °C in the shallow nearshore zone with 1 m deep water. The warm lake-bottom causes considerable disturbance to the permafrost. Surveyed data show that there is no permafrost under the lake when the mean annual lake-bottom temperature is over 5 °C. 相似文献
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The efficacy of carnivore and ungulate fecal chemicals in suppressing the feeding behavior of Alpine goats (Capra hircus) was examined. In the first four experiments, goats were offered food covered with paper strips treated with fecal extracts of the Bengal tiger, Siberian tiger, African lion, and brown bear, respectively; food covered with solvent-treated and untreated (plain) papers served as controls in each experiment. Goats made fewer head entries into, and ate less food from, buckets containing fecal extracts. In the fifth experiment, goats were offered food covered with paper strips treated with fecal extracts of the puma, Dorcas gazelle, white-bearded gnu, and conspecifics; food covered with solvent-treated and plain papers again served as controls. The amounts of food consumed from buckets containing puma, gazelle, gnu, and solvent treatments were statistically indistinguishable, but less food was consumed from them than from buckets containing the goat-scented or plain papers. No significant differences among treatments were detected with respect to head entries. Field experiments are needed on the use of predator-derived chemicals to reduce damage by goats to vegetation. 相似文献
7.
Extensive damage to the vegetation cover in arctic and alpine landscapes has raised the question of restoration as a possible management strategy. Restoration is a goal-oriented activity, a technological undertaking wider than its parent science of ecology. Social science and planning concepts and methods are necessary to handle the value judgements implicit in restoration. It is argued that the notion of 'desired state' is a better reference point in defining restoration goals than the notion of 'original state'. Using qualitative methods, two areas with vulnerable arctic/alpine vegetation are investigated. Based on participants' statements, four possible scenarios or desired states for future management are constructed. The main focus in the scenarios is on participants' attitudes to restoration activity, and it is shown how these are influenced by participants' attachment to the area and their view of nature. 相似文献
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ABSTRACTConcentrations of cadmium (Cd) were determined in the samples of 144 animals around 1 and of 144 animals around 4 years old. Cd was analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES), after microwave digestion. Cd concentrations were higher (p < 0.05) in kidney than in liver and higher (p < 0.05) in older animals than in young ones. In domestic Balkan goat which was raised in a free-ranged system Cd accumulation was lower (p < 0.05) than in Alpine goat raised in an intensive production system. Geographic region did influence Cd accumulation only in older animals. Higher Cd levels (p < 0.05) were determined in goats from Serbia. The highest obtained Cd concentrations in both tissues were lower than maximum levels set by European and national legislation for ruminants (cattle and sheep). 相似文献
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