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208 Uppsatser om Key habitat - Sida 1 av 14

Flottledsåterställning i norra Sverige: : effekter på habitatkvalitet och populationstätheter av juvenil öringar (Salmo trutta L.)

In an effort to evaluate the effects of restorations of float ways on population density of stream dwelling fish in relation to the changes in habitat, I studied the physical habitat restored and channalized sites and their population density of brown trout (Salmo trutta L.) in three streams in the municipality of Sorsele. The differences between the channalized and the restored sites where most noticeable regarding substrate which where generally coarser in the restored sites. The analyses showed that the proportion of habitat that where suitable to the age class 0+ where significantly lower in the restored sites compared to the channalized sites. Regarding age class ?2+, no statistical differences in habitat quality were found.

Pre-spawning habitat selection of subarctic brown trout (Salmo trutta L.) in the river Vindelälven, Sweden

Habitat selection of migratory brown trout at the upper reaches of River Vindelälven, wasstudied in September during the pre-spawning period. The fish migrate from down- orupriver lakes for spawning in the river and data was collected by habitat mapping andradio-telemetry. Habitat selection of fish was analysed with preference curves andstatistical modelling, using the physical variables; depth, stream velocity and streambedsubstrate. Preference curves were derived by comparing fish habitat use with their nearbyavailable environment while the statistical modelling aimed to answer three main questions.1) Do the trout have a specific preference of depth, water velocity and streambed substrate?2) Is there any difference in habitat selection between sexes? 3) Is there a shift in habitatselection over time? The preference curves indicated that trout favored water depths of 1-2m, velocity compositions characterized as glides (c.

Squatting i Alexandra : Om illegal bosättning i Sydafrika och hur landets bostadspolitik påverkats av Habitat II

Squatting innebär att människor illegalt bosätter sig på mark eller ockuperar tomma hus för att ha någonstans att bo. I samband med att världens storstäder växer, växer även squattingområden. För att förbättra situationen för bland annat squatters, hölls 1996 en FN-konferens, Habitat II.Syftet med uppsatsen är att belysa problemet med squatting och undersöker om Habitat II:s beslut haft någon inverkan på det deltagande landet Sydafrika. Den teoretiska ansatsen är realism och managerialism, där man menar att bostadssegregation beror på sociala och rumsliga hinder, samt att det är de med makt som ansvarar för bostadsituationen. De dokument från Habitat II har studerats som berör squatters samt sydafrikanska bostadspolitiska dokument.

Fåglar i urbana miljöer : kvaliteten på urbana habitat och om beståndstäthet är ett bra mått på habitatkvalitet

The urbanization of the world is increasing. How it affects bird populations have been well studied during the last decade, and comparisons between urban and non-urban habitats have been carried out. A common method for measuring habitat quality is to calculate the population density. This method is easy to use, but have been criticized during the last couple of years. In this study, data of population densities was compared with data on reproduction success.

En undersökning av Bergvik skogs och Skogsstyrelsens gallringsmallar mot en gallringsoptimering på simulerade typbestånd

The purpose of this study was to analyze the two thinning models: Bergvik Skog´s thinning model, which is based on total stems and dominant height, And Swedish forest agency´s thinning model which is based on basal area, habitat index, dominant height and recommended number of stems at final felling in Heureka´s StandWise and PlanWise. The data we chosen for our study were taken from the Swedish National Forest Inventory and we were creating a simulated stand based on a great number of sample plots in Region three from The Swedish National Forest Inventory. We had chosen to create one stand with low habitat index (T20) and one with high habitat index (T24). Our purpose were to come as close as possible to a natural stand in central Sweden. We performed the thinning in StandWise and analyzed the data I Excel files. Our thinning optimizing´s were performed and analyzed in PlanWise. There wasn´t any big differences between the thinning on the lower habitat index.

Habitat diversity and composition among growing wild boar (Sus scrofa L.) populations in Sweden

The wild boar (Sus scrofa L.) has expanded across Europe and Sweden in the last decades. It is a generalist species which utilizes a variety of habitats, and its presence has been shown to have both positive and negative effects for people and the landscape they are in. The abundance and increase of wild boar has previously been shown to differ between counties in Sweden, but there have been few explanations as to why. In this study, I investigated correlations between the per capita rate of change (r) among wild boar populations in Sweden and a variety of different habitats on the county level. I also investigated if fragmentation per se or in certain habitats could be associated with the wild boar?s per capita rate of change. My results show that fragmentation/diversity per se was not correlated with wild boar r.

Influence of the habitat on the potential for cannibalism and population dynamics in stream-dwelling European grayling (Thymallus thymallus L.)

Cannibalism can have major influence on fish population dynamics. A prerequisite for cannibalism is that the cannibal and the potential victim meet, and besides density effects, the encounter rate between cannibals and their victims is therefore also largely dependent on habitat use and habitat heterogeneity. In this study I quantified and compared the potential for cannibalism in stream-dwelling European grayling populations in three rivers in Jämtland by means of habitat classifications. I also analyzed population dynamic consequences of varying the potential for cannibalism in terms of intensity, using a physiological structured population model. Findings based on habitat characteristics were that the potential for cannibalism is in general not favourable in these types of streams.

Neonate mortality in fallow deer (Dama dama) in relation to bed-site selection and habitat use

The level of neonate mortality in a free ranging fallow deer (Dama dama) population at the Koberg estate in south western Sweden was investigated using radio-tracking techniques. During this study a total of 36 fawns (17 ?, 19 ?) were captured and marked with vhf or gps radio collars; 12 fawns in 2008 and 24 fawns in 2009. The neonate mortality calculated by the Kaplan-Meier method was 23.6 % and the mortality caused by predation was low, since only 1 of 8 non-surviving fawns died from predation by red fox (Vulpes vulpes). The spatial behavior of the fallow deer neonates were examined at two different levels i.e.

Selection of habitat and resources during migration by a large mammal : a case study of moose in northern Sweden

Migration is a worldwide phenomenon that has occurred for thousands of years in a vast variety of species. The general knowledge of migrating animals is poor even though billions of animals from a range of different groups migrate every year. The human impact on migrating ungulates is high and many populations are declining globally due to direct and indirect causes. Hence it becomes vital to study the migration phase and the habitat and resources selected during migration. The objective with this study was to identify the habitat characteristics and resource selection of moose during migration and compare the selection between different seasons and utilization distribution (relative frequency distribution for the points of location of an animal over a period of time) categories.

Habitatmanipulering, en tveeggad bekämpningsmetod? : potentiella möjligheter och risker med alternativa födoresurser och skyddande habitat

Bevarande biologisk bekämpning är en bekämpningsstrategi som används för att bevara eller öka mängden av en specifik naturlig fiende till den skadeorganism som ska bekämpas. En skillnad i jämförelse med andra strategier inom biologisk bekämpning är att inga biologiska bekämpningsorganismer tillförs, i stället främjas de naturliga fiender som redan finns i odlingen och det omgivande landskapet. Habitatmanipulering är en metod inom bevarande biologisk bekämpning som bygger på en förändring av de naturliga fiendernas habitat som skall resultera i en förbättrad tillgång av nödvändiga resurser så som alternativ föda, skyddande habitat och alternativa bytes- och värddjur. Den här litteraturstudien undersöker potentiella möjligheter och risker med två metoder inom habitatmanipulering. Den ena metoden bygger på att inkludera blommande växter i en odling för att skapa en förbättrad tillgång av alternativa födoresurser, så som pollen och nektar, till naturliga fiender.

Habitat preference and dispersal of a sandassociated beetle, Apalus bimaculatus

Species that have a high degree of specialization and poor dispersal ability can be more prone to extinction than more generalist species and good dispersers. How these species traits affect the viability of populations is dependent on landscape factors,such as isolation and connectivity. Additionally, interactions between species (e.g. symbiosis), and how these interactions vary spatially and temporally can have a large impact on populations. When the range and habitat areas of a species continuously decrease, management strategies are often needed if the species shall be able to survive.

Balis trädgårdar

The urbanization of the world is increasing. How it affects bird populations have been well studied during the last decade, and comparisons between urban and non-urban habitats have been carried out. A common method for measuring habitat quality is to calculate the population density. This method is easy to use, but have been criticized during the last couple of years. In this study, data of population densities was compared with data on reproduction success.

GIS-modellering av habitat för vitryggig hackspett (Dendrocopos leucotos) som hjälpmedel i naturvårdsplanering på landskapsnivå :

The white-backed woodpecker is a forest bird being critically endangered in Sweden. The species is dependent on older forests rich in deciduous trees and dead wood. The main problem for the survival of this species is present shortage of habitat. Conservation work on this umbrella species is at present focused on finding remaining or emerging habitat networks. Large areas are scrutinized in search for suitable habitats to be protected or managed for the species sake.

Sand pits as habitat for ground beetles (Carabidae) : does the area affect species number and composition?

Sand pits are a valuable habitat which can hold many sand living species including several endangered ones. As many sand habitats with exposed sand are declining, sand pits have a potential as a substitute habitat. This study was conducted to see what effect the area of a sand pit has on species number and composition of ground beetles (Coleoptera: Carabidae). Also, the effects of other environmental variables were tested, for example the proportion open sand, vegetation cover, sun exposure and tree cover. The study was conducted in the county of Uppsala in 2008 and included 13 sand pits with areas between 200 and 180,000 m2.

Vems landskap ska förändras för att öka den biologiska mångfalden? : En studie av skillnaderna i odlingslandskapets konnektivitet med avseende på två skyddsvärda arter med olika preferenser

Organisms relevant for nature conservation dont follow administrative borders. Because of this there is a need for a landscape perspective within conservation and planning, and a need for the species of interest to have legal protection. Network analysis adapted for ecological purposes has grown to become a powerful tool for studying and communicating the relationships between species dispersion and access to habitat. In this study the following question is posed: How is the Osmoderma eremita and the Pernis apivorus dispersal possibilities in the small scale cultivated landscape of Borås affected by exploitation in respect to a) dispersal ability, b) habitat quality, c) position of habitat patches in a network? The analysis were based on municipal and regional nature conservation data, which in due to confidentiality is not accounted for in the report by maps, coordinates, etc.

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