Manual of beaver management within the ... - DANUBEPARKS

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Manual of beaver management within the Danube river basinGenerally, they prefer soft woods. In several regions of its distribution area, beaverresidence is conditional on the occurrence of willow and poplar. In our region, such atight bond was not observed. Beaver gnaws even coniferous trees, although it stickshis teeth with resin. On the other hand, gnawing of (invasive species) ashleaf maple(Negundo aceroides) and black locust (Robinia pseudoacacia) is very limited.Beavers gnaw especially younger and juicier trees. Woody plants with a trunk ofdiameter
Manual of beaver management within the Danube river basinbeaver population on the ecosystem of the mountain stream, with a characteristic fishassemblage dominated by trout Salmo trutta morpha fario as positive for the whole fishstock. In particular, they highlight the increased supply of wood, increasing the shelterand food opportunities for invertebrates and the whole food chain, including trout.Beaver was brought into the basin of the upper San River in the Bieszczady to restorethe ecosystem disrupted by conveying wood by bed of mountain streams which wereused as road. In the beds of streams all shelter options and retention capacity havebeen destroyed (KUKULA 2003). After the release of beavers, status of ichthyofaunaimproved significantly (Negrylów stream). It was confirmed that environmental changesinitiated by beavers had a positive impact on ichthyofauna of studied stream. The studyalso showed that the beaver is clearly important for the restoration of degraded aquaticecosystems and accelerates their revitalization. Data did not confirm the negativeimpact of beaver on fish. In fact, by building weirs, beaver creates habitats to overcomeperiods of low water level, where even larger fish can survive. KUKULA & BYLAK (2010)indicate that trouts of TL> 20 cm were found exclusively in deeper water of beaverreservoirs, where numerous shelters were located in tree roots and stems submergedby beaver.Transverse structures fragment fish habitats on streams of each size. The same shouldapply to beaver weirs. When comparing the transverse structures of man and beaver,the difference in fish abundance is interesting. Beaver weirs unlike human structuresare an important element enrichiching sheltering and feeding opportunities of aquaticanimals. Beaver dam is partially water permeable with number of apertures used by thefish. KUKULA & BYLAK (2010) proved overcoming of beaver weirs by fish in increasedspring flows without difficulty. Durability of beaver weirs is altered by large water flow,beavers themselves partialy discharging accumulated water at high flow rate, as wellas by longevity of beaver families.Reduction of water flow above and below the dam leads to increased sedimentation,decreased dispersion of organic matter and increase in water temperature. In terms ofwater chemistry, it is usually accompanied by a decrease in oxygen saturation anddisappearance of sensitive species. In beaver ponds KUKULA & BYLAK (2010) measuredthe average oxygen content (10.3 mg/l) significantly higher than the minimumrequirement of salmonid fish. Beaver weirs changed the basic characteristics of amountain stream, creating a new habitat with deep, but well oxygenated standingwater.20
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Manual of beaver management within the ... - DANUBEPARKS

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