Recent surveys have shown that in Albania otters occur on rivers which had been judged unsuitable in the 1980s, pointing out the need for further investigations. We assessed otter distribution on a 60 km long stretch of the River Drinos, a major tributary of the River Vjosa. Marking intensity was assessed in two seasons, spring and summer 2010, corresponding to the highest and lowest river discharge levels, respectively. Otter signs (spraints and jellies) were searched for along 300 river stretches 200 m long (sampling stations). Vegetation coverage, hydraulic pattern and human disturbance were assessed visually for the whole length of each sampling
station. Both the mean number of sprainting sites and otter signs per 200 m of watercourse were higher in spring (0.81 and 2.6, respectively) than in summer (0.55 and 1.25). In spring otter signs were recorded in 118 sampling stations (39 %), while in summer, when the first 24 km of the watercourse were completely dried up, 92 sampling stations were positive for otters (31 %). Considering only the permanent river course, the variation in otter distribution was less marked (58 % vs. 51 % of 181 sampling stations). According to previous studies, the number of sprainting sites was correlated to vegetation cover, whilst variation in the hydraulic pattern of the
permanent river stretch did not influence marking intensity. Our results suggest that pollution control and habitat restoration can favour otter expansion in the river plains of central and southern Albania.
Occurrence of alien plant species in all the major habitats in the Czech Republicwas analysed using a data set of 20,468 vegetation plots, classified into 32 habitats according to the EUNIS classification. The plots contain on average 9.0% archaeophytes and 2.3% neophytes; for neophytes, this proportion is much smaller than 26.8% reported for the total flora of the country. Most neophytes are found in a few habitats: only 5.6% of them were recorded in more than ten habitats. By contrast, archaeophytes, and especially native species, tend to occur in a broader range of habitats. Highest numbers of aliens were found on arable land, in annual synantropic vegetation, trampled habitats and anthropogenic tall-forb stands. These habitats contain on average 22–56% archaeophytes and 4.4–9.6% neophytes. Neophytes are also common in artificial broadleaved forestry plantations; they also tend to make up a high percentage of the cover in wet tall-forb stands, but are represented by fewer species there. Entirely or nearly free of aliens are plots located in raised bogs, alpine grasslands, alpine and subalpine scrub and natural coniferous woodlands. Correlations between the number of archaeophytes or neophytes and the number of native species, calculated with habitat mean values, were non-significant, but there was a positive correlation between the numbers of archaeophytes and neophytes. The ratio of archaeophytes to neophytes was high in semi-natural dry and mesic grasslands and low in disturbed habitats with woody vegetation, such as artificial broadleaved forestry plantations, forest clearings and riverine willow stands. When individual plots were compared separately within habitats, the relationships between the number of archaeophytes, neophytes and native species were mostly positive. This result does not support the hypothesis that species-rich communities are less invasible, at least at the scale of vegetation plots, i.e. 10 0–10 2 m2.