Sök:

Sökresultat:

886 Uppsatser om Boreal forest - Sida 1 av 60

Ökad kollagring i boreal skog : Kan blädningsbrukad skog lagra mer kol än trakthyggesbrukad skog?

This study was conducted to test the hypotheses that a forest managed by selective cutting can store more carbon than a forest managed by clearcutting. The study was carried out as a meta-analysis. The data that was found was analyzed by performing t-tests on the proportional effect that the two silvicultural methods had on the driving factors of CO2-efflux and carbon stores in coniferous Boreal forest. In all areas tested, an effect in favor of selective cutting was found, but not all of them significant however. The soil respiration following selective cutting was significantly lower than that of clearcutting, and the primary production of a clearcut area cannot according to reason exceed that of an area post-selective cutting.

Hur en ökad marktemperatur påverkar fotosyntes och markrespiration i en boreal skog

During the year of 2008, a powerful earthquake hit the southern part of Iceland, which changed the geothermal conditions in the area around the city of Hveragerdi. Elevated soil temperatures in a nearby forest plantation have contributed to a unique opportunity for researchers to study how an increased soil temperature affects the Boreal forest ecosystem, something that partly can be connected to the climate changes which are happening today. The Boreal forest is representing a carbon sink and a buffert for the emissions that occurs. Changes in this ecosystem will for that reason contribute to major impact for the global carbon cycle. To study the impact of how elevated soil temperatures affects different processes in a plantation of Sitka spruce, studies were made on the photosynthesis of the trees and the respiration from the soil.

Nitrogen fixation among boreal feather mosses along a clear-cut chronosequence

The Swedish Boreal forests are limited by nitrogen (N) availability. While biological N2 fixation by cyanobacteria hosted by pleurocarpous feather mosses are important sources of N input to natural Boreal forest ecosystems, little is known about the patterns of N2 fixation in silvicultural systems. This study investigates the biological N2 fixation rates of two boreal feather moss species (Pleurozium schreberi and Hylocomium splendens) along a chronosequence from clear-cut to mature forest, as well as the vegetation characteristics along the chronosequence. Measurements and samples were collected from 32 forest sites that were classified into four age classes (clear-cut, pre-commercially thinned, thinned and mature forest). The sites were located near the city of Arvidsjaur in northern Sweden.

Naturvårdshänsyn i boreal bruksskog : En studie om avverkningar och avverkare i skogarna runt Saxdalen i södra Dalarna

As the past century?s technological development has progressed the Swedish Boreal forests have transformed into dense, highly productive, homogenous and coniferous forests. The area around Saxdalen in Ludvika municipality has long been dominated forests which have been heavily worked since the 18th century. There are in Ludvika 119 000 hectares of productive forest land. Around 70 percent are owned by forest companies and 20 by private forest owners.

Epixylic, forest-interior bryophytes in young stands : importance of local environmental variables, propagule sources, and distance to bordering woodland key habitats

The reduction of coarse, dead wood is considered to be the biggest threat to flora and faunain Boreal forests. Extensive harvest of logging residues would increase this reduction evenmore. However, the role of dead wood created at final felling for boreal, epixylic species isstill largely unclear. It is therefore of interest to examine whether epixylic species inhabit thedead wood in young, boreal stands, especially species considered to be confined to forests inlate successional stages.The aim of this study was to investigate whether forest-interior species in fact can inhabitearly-successional forests arisen after logging. The study was conducted in young standsbordering dead wood rich woodland key habitats.

Environmental variables determining the occurrence of the red-listed Carbonicola anthracophila and C. myrmecina in boreal forests

The global biodiversity loss is mainly due to human activities such as an intensification of forestry. Boreal forest ecosystems in Fennoscandia are characterized by disturbances such as forest fires, storms and floods. However, industrial forestry practices suppress forest fires and change the landscape, leading to a loss of habitats and associated species. Particularly lichen species with slow adaptation abilities and a strong substrate specificity face an extinction debt in Boreal forests since their substrates are long-lived but no longer created. In this study the species-substrate relationship of two red-listed forest-fire dependent lichen species Carbon-icola anthracophila and C.

Brandrelaterade insekters lokala artrikedom i förhållande till olika miljövariabler : Fokus på betydelsen av konnektivitet på brandfält i boreal skog i Västerbottens län

The last century, forest fires have decreased in frequency due to efficient fire-suppression along with the growth of the industrial forestry. Since 1990, fire has been reintroduced under controlled forms to recreate burnt habitats. Many species that are dependent on, or benefits from, forest fires have increased since fire was reintroduced. The importance of connectivity is often addressed in ecological research. This is particularly important for species dependent on short-lived habitats such as burnt forests.

Autumn water sources for understory vegetation and fungi in a boreal forest : an evaluation using stable isotopes

Understory vegetation and fungi are regarded as important ecological drivers of processes like productivity and nutrient cycling in Boreal forests. Whilst those processes are linked to soil water content, relatively little is known about the sources of soil water for these forest components. During early autumn in Boreal forests, temperature falls and large events of rain are frequent which may influence soil water availability. To better understand the autumn plant-soil-fungi water relationships in this ecosystem, I used stable isotopes techniques in this study to examine the water sources for ericaceous shrubs and fungi in a Scots pine forest following a large, early autumn rain event. I hypothesize that ericaceous shrubs of two functional groups (evergreen vs.

Habitat use and ranging behaviour of GPS tracked juvenile golden eagles (Aquila chrysaetos)

Throughout its wide distribution in the northern hemisphere, the golden eagle occurs in a diverse range of environments, e.g., mountainous, forest and open areas. The literature on juvenile golden eagles is limited, and this study provides further knowledge on habitat use and ranging behaviour during the post-fledging period in boreal Sweden. A total of 14 golden eagle juveniles were tagged with GPS transmitters during 2010 and 2011, and nine could be followed during the entire post-fledging period from fledging until migration. The juveniles fledged at the end of July and beginning of August and initiated migration during October and beginning of November. The length of the post-fledging period, until migration started, ranged from 49 to 97 days. During this period, the juveniles? distance from their natal nest and their GPS height increased with time as their flying abilities developed.

Examining the social component of sustainable forest management in Prince Albert and Vilhelmina Model Forests

Due to the forest industry downsizing, many communities in rural forest regions in Canada and Sweden are facing problems to survive. In order to create community sustainability, resilience and well-being in remote forest regions, the view on the forest resources has shifted towards multiple use, through the concept of sustainable forest management (SFM). Beside the economic and ecological elements of sustainability, the social forest values are needed, contributing to the human well-being, local participation, stakeholder collaboration, human rights and cultural connection. In this thesis the embodiment of the social component of SFM within Prince Albert Model Forest (Canada), and Vilhelmina Model Forest (Sweden) will be examined. Being partners and facing similar challenges as rural Boreal forest regions, the two model forests are compared through analysis of projects and activities, conducted interviews and organization documents. Looking at projects mentioned as successful by the interviewees, they all have elements from the social values of SFM. The direction can be explained by the introduction of the Forest Communities Program in Canada, demanding the Model Forests to work towards community stability and resilience, the Model Forest organization concept itself and the way global focus are increasing around social forest values. In the future, it may be important that the role of the MFs enable some kind of political authorization and legitimacy in order to improve conflict solving and indigenous rights equality.

Environmental variables determining the occurrence of Cladonia parasitica and Hertelidea botryosa, two boreal lichens confined to wood

Biodiversity is essential for human well-being and it is defined as the genetic variation within species and the variety of species and ecosystems. Biodiversity provides several ecosystem services which are necessary for human beings but there are different threats towards the biodiversity. The biodiversity linked to the forest in Sweden are threatened, about 50 % of the red-listed species in Sweden are associated with forests. This is linked to the commercial exploitation of the Boreal forest in Sweden which started 200 years ago. The forestry the last 50 years, with clear-cuts, have contributed to a fragmented forest landscape.

Mapping of clear-cuts in Swedish forest using satellite images acquired by the radar sensor ALOS PALSAR

This study presents results for observing forest changes in Sweden using multi-temporal L-band satellite data and is a part of the JAXA?s ALOS Kyoto and Carbon Initiative. An extensive dataset of images acquired by the Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) is investigated for clear-cut detection in Boreal forests in northern Sweden (Lat. 64°14? N, Long.

Grey-sided vole and bank vole abundance in old-growth forest patches of different size and connectivity

Vole populations in northern Scandinavia vary in cycles with peaks every third or fourth year as described by the National Environmental Monitoring Programme of small mammals (NEMP). Some vole species have declined in population numbers since the NEMP started in 1971, especially the grey-sided vole (Myodes rufocanus) which is nearly extinct in the forested region. Since small mammals are an important food source for several avian and mammalian predators, the decline in vole numbers is expected to have consequences for the whole food chain, especially if other vole species start to decline in numbers. This study tried to test the hypothesis that presence and abundance of M. rufocanus (a specialist species) and Myodes glareolus (a generalist species) can be predicted by patch size and connectivity of forest patches >60 years old with a minimum of 15% pine >100years old.

Evighetsträd

FSC (Forest Stewardship Council) is the major form of certification system in Swedish forestry today and its more than 11 million hectares are covering almost half of the total productive forest area in the country. Its regulations prescribe that at least 10 wind firm trees should be left behind after every clear cutting operation. This study have taken place on 30 recently clearcut objects in Bergslagen, Sweden, were an inventory of the standing stock have been made. The research shows that, with 90 % security, the retained trees together contain 9-13 m3sk per hectare. Pine is the dominant tree and it covers more than half the numbers of retained trees and its volume cover 65 % of the retained trees total volume. Spruce is on second place with 30 % of the retained trees, but only 21 % of the standing stock.

Utsläpp av växthusgaser under islossning i små boreala sjöar

Freshwater ecosystems have long been neglected as an important part of the global carbon cycle. However, research shows that most of the world?s lakes are net-heterotrophic and consequently emitters of greenhouse gases to the atmosphere. In many boreal and north-temperate lakes, most of the yearly emissions usually occur in spring, shortly after ice-thaw. The aim of this study was to quantify the flux of carbon dioxide (CO2) and methane (CH4) in three boreal lakes, during this annual event.

1 Nästa sida ->