Hartmut Gossow

Impact of ungulates on forest vegetation and its dependence on the silvicultural system

Abstract In order to obtain an understanding of the forest-ungulate compartment in the ecosystem with the aim of better management, the impact of ungulates on forest vegetation, as well as the impact of habitat structure and dynamics on ungulates (density, distribution etc.) and on the forests predisposition to game damage were investigated. It is shown that browsing and peeling impact depends markedly on silvicultural techniques. The attractiveness of habitats for game depends not only on food supply, but also, to a high degree, on food-independent habitat factors such as terrain conditions, climate, edge effect, disturbance and competition impact, and thermal and hiding cover availability. Forests with a badly managed ratio of settling stimulus to available food act as ‘ecological traps’, where the food needed for the over-abundant game ungulates is taken increasingly by the twig browsing and bark peeling of timber species. In general, one can say that a clear-cut system is attractive to deer and chamois. It is easy to hunt in, but it is susceptible to game damage. In particular, clear cutting in narrow strips and reafforestation have a high predisposition to game damage. In contrast, selective silviculture results in a more balanced system with less impact by ungulate game on forest vegetation, though hunting might be more difficult. Higher deer densities need not be associated with greater browsing damage; such damage also depends strongly on the growing-stock target and the silvicultural system. If forestry practices are ‘close to nature’, an abundance of ungulates may also result in a greater density of forest regeneration and a better mixture of tree species. The potential impact of ungulates on forest regeneration, man-made disturbances of the ungulate-vegetation system, and silvicultural measures to avoid game damage are discussed.

The impact of high speed, high volume traffic axes on brown bears in Slovenia

Abstract The Ljubljana–Razdrto highway and the parallel Ljubljana–Trieste railway cut through critical brown bear ( Ursus arctos ) habitat in south-central Slovenia. These high speed, high volume traffic axes are located close to the main dispersal corridor for bears from the Dinaric Mountain range into the Alps. We analyzed radiotracking data of 15 individual bears that lived within 10 km of the highway, compared transportation related and overall known bear mortality, and analyzed the spatial distribution of bear–vehicle accidents. The highway posed a home range boundary to resident bears, but was not an absolute barrier. Transportation-related mortality was high in the vicinity of the highway and railway, and averaged 31% of the total known local mortality from 1992 to 1999. At present the detrimental impact of transportation routes on the bear population in Slovenia is modest due to the high density of bears and the low density of highways—but new highways are planned or already under construction. Managers have to be aware that, due to bears large home ranges and long dispersal distances, a single highway affects bears from a huge area—emphasizing the importance of international cooperation and a landscape approach in highway planning.

Displaying behaviour and mating system in the Siberian Spruce Grouse (Falcipennis falcipennis Hartlaub 1855)@@@Balzverhalten und Paarungssystem des Sichelhuhns (Falcipennis falcipennis Hartlaub 1855)

The Siberian Spruce Grouse (Falcipennis falcipennis) is a species endemic to far-eastern Russia and a close relative toF. canadensis andF. franklinii of North-America. Prior to this study, little was known about the display behaviour, social organisation and seasonal movements of this grouse. We investigated these topics in 1990–1997, in 2 areas, 100 km N and 200 km NW of Komsomolsk/Amur. We caught, measured and marked 80 individuals. We determined the age of cocks by the size of combs and the length of neck feathers. Spatial organisation of the local population was studied by equipping 60 birds with transmitters and following them all-year-round. During the reproductive period males and females were territorial. Winter flocks (2–6 birds) break up by late March or early April, and spring flocks break up 1 month later. Cocks were present at the display ground from April 1 to May 25. Females visited the display grounds from April 25 to May 10. Eggs were laid between May 7 and May 20. The main display performances of cocks (upright posture and tail flicks, walks with tail swish, flutter jumps, flutter flights, drumming flights), courtship and agonistic behaviour were analysed from photographs and video recordings. Three-year-old cocks carried out most of the copulations. During the “high season” of display, we recorded activity (morning and evening displays, moving versus roosting) during continuous observations and counted flutter jumps, flutter flights and drumming flights. Parts of the displays of the Siberian spruce grouse are more diversified than those of the North-American species. The communication system is perfectly adapted to the dense habitat of the mountain taiga. Different acoustic signals for communication at very short, medium and longer distances seem to have evolved under specific predation pressure. The territorial system is very flexible, ranging from individual display grounds to an arena-like structure. The mating system is polygyny. Das Sichelhuhn (Falcipennis falcipennis) als endemisches Raufußhuhn des Fernen Ostens Russlands ist eng verwandt mit den nordamerikanischen FichtenhühnernF. canadensis undF. franklinii. Von 1990–1997 wurden Ökologie und Verhalten dieser Art in zwei Gebieten (100 km N und 200 km NW von Komsomolsk am Amur) studiert. 80 Vögel wurden gefangen, vermessen und markiert. Zwei Maße (Größe der Überaugenwülste und Halsfederlänge) gestatten eine Altersbestimmung der Hähne. 60 besenderte Vögel lieferten rund um das Jahr Daten zu Raum- und Habitatnutzung, Reproduktion und Mortalität. Individuelle Markierung und Ortung zu beliebigen Zeiten erleichterten auch die Verhaltensstudien. In der Reproduktionsperiode besaßen sowohl Hähne als auch Hennen Reviere. Winterflüge aus 2–6 Vögeln lösten sich Ende März/Anfang April auf; die Frühjahresgruppen einen Monat später. Die Hähne waren im Mittel zwischen 1. April und 25. Mai an den Balzplätzen anzutreffen, die Hennen erschienen dort zwischen 25. April und 10. Mai. Zwischen 7. und 20. Mai erfolgte die Eiablage. Die wichtigsten Elemente des Territorialverhaltens (Aufrechthaltung mit Schwanzspreizen, Imponierläufe mit Schwanzfederzischen, Flattersprünge, Flatterflüge und Trommelflüge), Revierverteidigung und Werbung werden nach Foto- und Videoaufzeichnungen beschrieben. Dreijährige Hähne vollzogen die meisten Paarungen. Zwischen 1. und 9. Mai, wenn Werbe- und Paarungsverhalten kulminieren, wurden durch Ganztagsbeobachtungen Morgen- und Abendaktivität, Ortsveränderungen und Ruhephasen quantitativ erfasst, ebenso der tägliche Anteil von Flattersprüngen, Flatter-und Trommelflügen. Im Vergleich zu den nordamerikanischen Geschwisterarten sind Teile des Verhaltensrepertoires des Sichelhuhns zur Balzzeit stärker differenziert. Das Kommunikationssystem ist an dichte Habitate der borealen Bergtaiga angepasst: Verschiedene akustische Signale, die auf sehr kurze, mittlere and längere Distanzen wirken, sind offenbar in Anpassung an den spezifischen Feinddruck entstanden. Das Reviersystem erscheint flexibel: Die Spanne reicht von solitär agierenden Hähnen bis zu Arena — ähnlichen Balzplätzen. Das Paarungssystem ist Polygynie.

Fire — Vegetation — Wildlife Interactions in the Boreal Forest

The distribution and composition of wildlife in a given area is to a great extent the result of its actual vegetation conditions. In the boreal forest biome, arboreal as well as ground vegetation is predominantly a result of local site conditions and corresponding snow and fire regimes. There appears to be rather good agreement among scientists studying boreal forest-fire interactions, that “in the north, most natural forests are either maturing following the last fire or being instantly recycled by the next” (Heinselman 1981) — with emphasis on cycles instead of succession. Only locally, e.g. on the floodplains of rivers, may primary successions occur (Van Cleve and Viereck 1981); whereas secondary successions take place in specific “fire refugia” (cf. Zackrisson 1977).