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A study of fish fauna in a small hypertrophic lake was conducted in the spring, summer, and autumn of 2006-10. In total 11 fish species representing 4 families were found. The species richness was low, depending on the season, and ranged from 2 to 7 species. A variation of species dominance, depending on the year and season, was found. Total fish abundance and biomass were varied according to the season, but differences depending on the year had been noted only in fish biomass. The fish fauna was characterized by low values in indices of diversity and the estimated turnover rate of the fauna ranged from 0.09 to 0.56, and the regression analysis showed a significant growth in its upward trend.
We examined changes in the assemblage of bats in southern Lower Michigan, USA, using results of paired netting surveys conducted with similar techniques but separated by 12–26 years. Species diversity declined by 18–35% and evenness decreased by 0–35% throughout the region and in two specific areas. Changes in diversity and evenness were attributed primarily to decreases of 44% or more in relative abundance of the foliage-roosting eastern red bat (Lasiurus borealis). Number of L. borealis captured per net-night decreased 52–85%. The decline in relative abundance of L. borealis suggested by mist netting was supported by a 10-fold decrease over 38 years in the proportion of L. borealis that were tested for rabies by the state health laboratory. The apparent decline in L. borealis is especially alarming in light of the recent upsurge in use of wind power and the large number of L. borealis that are killed at such developments. We recommend that other previously completed surveys in eastern North America be duplicated, as one way of helping to confirm or refute the trend that we have identified.
The research has been aimed at studying both seasonal and annual changes in air temperature and precipitation over the past 40 years, i.e. from 1961 till 2000, as well as in 2001-2003 period. Additionally increase/decrease rates for all the parameters under analysis were to be determined, as well as thermal and precipitation rating of months over the studied period. The research was based on data recorded over respective 1961-2003 decades and months for air temperature and precipitation that were collected at Lipki agro- and weather station, near Stargard Szczeciński. Magnitude of the standard deviation (S) from the standard from 1961 to 2000 was applied as a criteria for thermal rating all the months over the studied period. To evaluate deficiency or excess of precipitation in particular months a criteria of percentage of total monthly precipitation over the standard value (75 - 125%) was applied. Monthly, seasonal and annual changes for both air temperature and precipitation tend to be linear. Over the studied period for all the moths, excluding November, a rising tendency for air temperature was observed. A statistically significant, positive trend was observed for April, May, July and August. The biggest increase for temperature, on average by 0.8°C/10 years, was found for January. No clear, solid trends have been detected for precipitation. At the beginning of a year a rising tendency was noticed, while towards the month end precipitation tend to drop. Still, only in May the trend was statistically significant and found negative. The year 2003, whose summer season was found exceptionally hot and very dry, was also evaluated in terms of temperature and precipitation.
In this study, we examine the pattern of occurrence of Impatiens parviflora in Central European oak forests over time and its ecological requirements within these types of communities. Research was based on phytosociological data collected in 3776 relevés. A modified TWINSPAN algorithm were used to distinguish the groups of oak forests. The ecological preferences of the I. parviflora and studied communities as well as differences between invaded and non-invaded vegetation plots were analyzed using mean weighted Ellenberg indicator values (EIVs). Finally, both the temporal pattern of I. parviflora participation and changes in its coverage in the studied communities were analyzed. Our study confirmed a high adaptability of this species with respect to temperature, moisture, soil reaction and nutrients and determined its broad ecological optimum in oak forests. However, it also revealed both a greater sensitivity of some communities within Central European oak forests to the invasion of I. parviflora and differences in habitat conditions between invaded and non-invaded vegetation plots. This suggests that the habitat niche of I. parviflora within oak forests is not accidental. The analysis of temporal changes in the frequency of I. parviflora confirmed a 20% increase in relevés over the last 50 years. However, we did not identify any statistically significant rise in the coverage of I. parviflora in oak forests specifically during the studied period.
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