The objectives of this study were two fold. The first was to quantify the nature and extent of current levels of human impact in alpine areas at four sites within Fiordland and Mount Aspiring National Parks along walking tracks at Key Summit, Gertrude Saddle, Borland Saddle and Sugarloaf Pass. In order to do so, a survey was carried out with transects placed perpendicular to the track, and distributed among different vegetation types. In each transect, plant structural and compositional aspects, and soil and environmental parameters were measured. Transects were divided into track, transition, undisturbed and control zones, and changes to dependent variables were compared with distance from the track centre. Damage from visitor impact was largely restricted to within 1m from the track centre. The most significant impacts were to structural aspects of plant and soil properties with significant reductions in plant height, total vegetation cover and bryophyte cover, and increases in bareground and erosion on tracks. Erosion was more prevalent on slopes greater than 25°, while tracks on peat soils contained greater bareground exposure, particularly of organic soil. The second study objective was to investigate the relationship between specific levels of impact and the resulting damage to two key alpine vegetation types, tussock herb field and cushion bog. This was undertaken by carrying out controlled trampling experiments, measuring changes to plant structural and compositional aspects four weeks and one year after treatment. Both vegetation types saw dramatic reductions in total vegetation cover and height immediately after trampling, however overall composition and species richness varied little. These two alpine vegetation types showed moderate-low resistance to initial impact and low resilience, with very little recovery evident one year later. Research intothese two areas is important for managing visitor use within alpine areas in order to meet conservation and recreation goals. The survey indicates that alpine community types are very sensitive to visitor use, showing significant structural damage, however the spatial extent of impact is limited within the broader landscape. Instead, visitor impacts associated with tracks are likely to be more visually and aesthetically significant, influencing the visitor experience. The trampling experiments indicate that use levels over 25-75 passes per year within tussock herbfield and cushion bog vegetation on peat soils will result in ongoing damage to previously undisturbed sites. Methods for minimising impacts include limiting visitor numbers, public education in low impact practices, redirection of tracks and use to areas that are less sensitive, the dispersal of visitor activity at very low use intensities (less than 75 direct passes per year) and the concentration of activity on tracks above this level.

The objectives of this study were two fold. The first was to quantify the nature and extent of current levels of human impact in alpine areas at four sites within Fiordland and Mount Aspiring National Parks along walking tracks at Key Summit, Gertrude Saddle, Borland Saddle and Sugarloaf Pass. In order to do so, a survey was carried out with transects placed perpendicular to the track, and distributed among different vegetation types. In each transect, plant structural and compositional aspects, and soil and environmental parameters were measured. Transects were divided into track, transition, undisturbed and control zones, and changes to dependent variables were compared with distance from the track centre. Damage from visitor impact was largely restricted to within 1m from the track centre. The most significant impacts were to structural aspects of plant and soil properties with significant reductions in plant height, total vegetation cover and bryophyte cover, and increases in bareground and erosion on tracks. Erosion was more prevalent on slopes greater than 25°, while tracks on peat soils contained greater bareground exposure, particularly of organic soil. The second study objective was to investigate the relationship between specific levels of impact and the resulting damage to two key alpine vegetation types, tussock herb field and cushion bog. This was undertaken by carrying out controlled trampling experiments, measuring changes to plant structural and compositional aspects four weeks and one year after treatment. Both vegetation types saw dramatic reductions in total vegetation cover and height immediately after trampling, however overall composition and species richness varied little. These two alpine vegetation types showed moderate-low resistance to initial impact and low resilience, with very little recovery evident one year later. Research intothese two areas is important for managing visitor use within alpine areas in order to meet conservation and recreation goals. The survey indicates that alpine community types are very sensitive to visitor use, showing significant structural damage, however the spatial extent of impact is limited within the broader landscape. Instead, visitor impacts associated with tracks are likely to be more visually and aesthetically significant, influencing the visitor experience. The trampling experiments indicate that use levels over 25-75 passes per year within tussock herbfield and cushion bog vegetation on peat soils will result in ongoing damage to previously undisturbed sites. Methods for minimising impacts include limiting visitor numbers, public education in low impact practices, redirection of tracks and use to areas that are less sensitive, the dispersal of visitor activity at very low use intensities (less than 75 direct passes per year) and the concentration of activity on tracks above this level.

Lic.-avh. Härnösand Uppsala : Mitthögskolan : Sveriges lantbruksuniv. : 2001. / Härtill 2 uppsatser.

No description available.

The object of this thesis was to study plant community structure, especially in relation to vertebrate herbivory, in an altitudinal gradient in the Fennoscandian mountain chain. A sowing experiment in a high alpine Ranunculus glacialis population showed that seeds germinated better in cleared microsites than under established individuals. This is contrasted with a hypothesis that predicts positive plant-plant interactions in high alpine environments. It was concluded that plant-plant interactions in die studied population varied from neutral to negative, whereas no indications for positive interactions were found. An exclosure experiment in a snow-bed showed that a lemming population consumed 33 % of the available graminoids and 66 % of the mosses from August to June during a population peak. The results shows that grazing needs to be considered as a structuring factor in snow-bed vegetation. The vegetation in exclosures in another snow-bed changed from a graminoid-dominated to a herb-dominated plant community during a long-term (six years) experiment No changes of the same magnitude were seen in a tall herb meadow on a lower altitude. Survival of transplanted adult shoots from the tall herb meadow was equally high in the snow-bed as on the meadow, and germination was also high on bare ground in the snow-bed. Grazing seemed to be a more important structuring factor in the snow-bed than in the more productive tall herb meadow. Raising the grazing pressure during one growing season by introducing microtine rodents into enclosures did not cause any large short-term effects on plant community structure in a tall hob meadow or in a snow-bed. Marked shoots showed that some preferred plant species had a high shoot mortality, but biomass for pooled categories of plants was not significantly affected. It was predicted that the tall herb meadow would be more grazing sensitive than die snow-bed, but productivity on the meadow seemed to be sufficiently high for the plants to compensate for the grazing during the growing season. A greenhouse experiment showed that voles, when grazing freely, have the potential to deplete productive field layer vegetation contrary to predictions from plant defence theories. A nitrogen-based defence did not prevent heavy shoot mortality for toxic tall herbs. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 5 uppsatser.</p> / digitalisering@umu.se

Les patrons de diversité caractérisent la structure de la diversité des communautés, c'est-à-dire sa valeur, sa distribution et son changement dans l'espace et le temps. Leur étude peut amener des informations importantes sur les processus écologiques qui en sont à l'origine. Cependant de nombreuses hypothèses de travail sont faites lors de leur analyse. L'idée générale de cette thèse est qu'en remettant en cause ces hypothèses, un certain nombre de développements liés aux indices de diversité et aux modèles nuls deviennent possibles et permettent de mieux comprendre les processus écologiques à l'origine des patrons de diversité fonctionnelle ou phylogénétique. Le premier chapitre est consacré à l'étude des patrons de diversité fonctionnelle des communautés végétales alpines à de multiples échelles spatiales et organisationnelles. Le second chapitre s'intéresse aux perspectives méthodologiques amenés par les nombres de Hill. Dans le dernier chapitre, on s'intéresse aux enjeux méthodologiques d'un nouveau type de données de communautés : l'ADN environnemental. / Patterns of community diversity refers to the structure of diversity, i.e. its quantification, its distribution and its turnover in space and time. Its study is likely to shed the light on the assembly rules that determined the structure of communities. However, numerous ecological assumptions are often made when studying diversity patterns. What motivated the work was the perspective that by relaxing these assumptions, a number of developments linked to diversity indices and null models are possible and can help to understand the impact of multiple ecological processes on phylogenetic and functional diversity patterns. In a first part we studied the pattern of functional diversity of alpine plant communities as a function of spatial and organizational scales. In the second part, we studied the methodological perspectives brought by the Hill numbers. In a third part, we addressed the main methodological issues of a new type of community data: environmental DNA.