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Plant community assembly is determined by species turnover and intraspecific trait variations (ITV) controlled by environment changes. However, little is known about how species turnover and ITV affect the responses of plant community to habitat changes and grazing disturbance in semiarid grasslands. Here, we measured five functional plant traits in four typical grassland habitats under fencing and grazing disturbance in a semiarid grassland, Northern China, including plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf carbon: nitrogen ratio (C:N). We also calculated the community weighted means (CWM) and non-weighted means (CM) of all traits and examined the relative roles of species turnover and ITV in affecting the responses of community traits to habitat changes and grazing disturbance. Our results showed that the CWM and CM values of five functional traits differed with grassland habitat changes. As compared to other grasslands, the Stipa steppe had the higher plant height, the sandy grassland had the higher SLA and lower LDMC, and the meadow had the lower LNC and higher C:N. Grazing decreased plant height across grassland habitats, as well as decreased SLA and increased LDMC in meadow. The responses of all community-level traits to habitat changes were driven by species turnover, while the responses of phenotypic traits (height, SLA and LDMC) to grazing were determined by both species turnover and ITV. So, we argue that ITV should be considered when understanding plant community assembly under grazing disturbance regime in semiarid grasslands.
Little Owl is a rapidly declining farmland species across Central Europe, however its population status is poorly known in Hungary. The main aim of this study was to determine the distribution and population density of Little Owl in Hortobagy National Park (northeastern Hungary), which is characterized by a high proportion of grassland habitats. During March and April of 2011–2012, the Little Owl occurrence was surveyed using tape-recorded stimulation in 245 sampling points in an area of 489 km². In total, we recorded 245 calling males with relative positive occurrence of 75.5% in an individual sampling point. The average nearest neighbour distance of two calling males was 553.6 meters (min. = 70 m, max. = 3100 m). The average population density of Little Owls was 5.01 calling males/10 km², however this could reach up to 85.97 calling males/10 km² in 3.06 km² locally. Residential buildings and farms were the main expected breeding places in our study area. High density of the Little Owl in the study area is probably influenced by traditional pastoral management, extensive agriculture and high proportion of grasslands. The particualar role could be atributed to presence of short-sward pastures around human settlements, considered to be crucial for the species survival in Central Europe. Further monitoring of the Little Owl is necessary to assess its current population status across various parts of its distribution range.
WeaselsMustela nivalis Linnaeus, 1766 in Kielder Forest, UK showed a diurnal rhythm of activity in summer and we argue that this is the prevailing rhythm found in weasels under natural conditions. Climatic conditions influenced weasel activity with weasels decreasing activity under rainy conditions, but we found no influence of month or weasel weight. In certain habitat types levels of weasel activity increased with increasing field voleMicrotus agrestis density. This result stands in contrast to results from studies carried out in the laboratory and may reflect a greater proportion of time spent in reproductive activity and intra-specific interactions in areas where vole density, and hence conspecific density is high.
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