24 resultados para Postfire salvage logging
em Helda - Digital Repository of University of Helsinki
Resumo:
Between 1935 and 1970 the state-funded Irish Folklore Commission (Coimisiún Béaloideasa Éireann) assembled one of the great folklore collections of the world under the direction of Séamus Ó Duilearga (James Hamilton Delargy). The aim of this study is to recount and assess the work and achievement of this commission. The cultural, linguistic, political and ideological factors that had a bearing on the establishment and making permanent of the Commission and that impinged on many aspects of its work are here elucidated. The genesis of the Commission is traced and the vision and mission of Séamus Ó Duilearga are outlined. The negotiations that preceded the setting up of the Commission in 1935 as well as protracted efforts from 1940 to 1970 to place it on a permanent foundation are recounted and examined at length. All the various collecting programmes and other activities of the Commission are described in detail and many aspects of its work are assessed. This study also deals with the working methods and conditions of employment of the Commission s field and Head Office staff as well as with Séamus Ó Duilearga s direction of the Commission. In executing this work extensive use has been made of primary sources in archives and libraries in Ireland, Sweden, Finland, Estonia, and North America. This is the first major study of this world-famous institute, which has been praised in passing in numerous publications, but here for the first time its work and achievement are detailed comprehensively and subjected to scholarly scrutiny. This study should be of interest not only to students of Irish oral tradition but to folklorists everywhere. The history of the Irish Folklore Commission is a part of a wider history, that of the history of folkloristics in Europe and North America in particular. Moreover, this work has relevance for many areas of the developing world today, where conditions are not dissimilar to those that pertained in Ireland in the 1930's when this great salvage operation was funded by the young, independent Irish state. It is also hoped that this work will be of practical assistance to scholars and the general public when utilising these collections, and that furthermore it will stimulate research into the assembling of other national collections of folklore as well as into the history of folkloristics in other countries, subjects which in recent years are beginning to attract more and more scholarly attention.
Resumo:
Forest management is facing new challenges under climate change. By adjusting thinning regimes, conventional forest management can be adapted to various objectives of utilization of forest resources, such as wood quality, forest bioenergy, and carbon sequestration. This thesis aims to develop and apply a simulation-optimization system as a tool for an interdisciplinary understanding of the interactions between wood science, forest ecology, and forest economics. In this thesis, the OptiFor software was developed for forest resources management. The OptiFor simulation-optimization system integrated the process-based growth model PipeQual, wood quality models, biomass production and carbon emission models, as well as energy wood and commercial logging models into a single optimization model. Osyczka s direct and random search algorithm was employed to identify optimal values for a set of decision variables. The numerical studies in this thesis broadened our current knowledge and understanding of the relationships between wood science, forest ecology, and forest economics. The results for timber production show that optimal thinning regimes depend on site quality and initial stand characteristics. Taking wood properties into account, our results show that increasing the intensity of thinning resulted in lower wood density and shorter fibers. The addition of nutrients accelerated volume growth, but lowered wood quality for Norway spruce. Integrating energy wood harvesting into conventional forest management showed that conventional forest management without energy wood harvesting was still superior in sparse stands of Scots pine. Energy wood from pre-commercial thinning turned out to be optimal for dense stands. When carbon balance is taken into account, our results show that changing carbon assessment methods leads to very different optimal thinning regimes and average carbon stocks. Raising the carbon price resulted in longer rotations and a higher mean annual increment, as well as a significantly higher average carbon stock over the rotation.
Resumo:
There are several reasons for increasing the usage of forest biomass for energy in Finland. Apart from the fact that forest biomass is a CO2 -neutral energy source, it is also a domestic resource distributed throughout the country. Usage of forest biomass in the form of logging residues decreases Finland’s dependence of energy import and increases both incomes and employment. Wood chips are mainly made from logging residues, which constitute 64 % of the raw material. A large-scale use of forest biomass requires heed also to the potential negative aspects. Forest bioenergy is used extensively, but its impacts on the forests soil nutrition and carbon balance has not been studied much. Nor have there been many studies on the heavy metal or chlorine content of logging residues. The goal of this study was to examine the content of carbon, macronutrients, heavy metals and other for the combustion harmful substances in Scots pine and Norway spruce wood chips, and to estimate the effect of harvesting of logging residues on the forests carbon and nutrient balance. Another goal was to examine the energy content of the clear cut remains. The Wood chips for this study were gathered from pine and spruce dominated clear cut sites in southern Finland, in the costal forests between Hankoo and Siuntio. The number of sample locations were 29, and the average area was 3,15 ha and the average timber volume 212,6 m3 ha -1. The average logged timber volume was for Scots pine timber 70 m3 ha -1 and for Norway spruce timber 124 m3 ha -1 and for deciduous timber (birch and alder) 18,5 m3 ha -1. The proportion of spruce in the logging residues and the stand-volume were relevant for how much nutrients were taken from the forest ecosystem when harvesting logging residues. In this study it was noted that the nutrient content of the logging residues clearly increased when the percentage of spruce in the timber volume increased. The S, K, Na and Cl -contents in the logging residues in this study increased with an increasing percentage of spruce, which is probably due to the fact that the spruce is an effective collector of atmospheric dry-deposition. The amounts of nutrients that were lost when harvesting logging residues were less than those referred to in the literature. Within a circulation period (100 years), the forest soil gets substantially more nutrients from atmospheric deposition, litter fall and weathering than is lost through harvesting of logging residues after a clear cut. Harvesting of the logging residues makes for a relatively modest increase of the quantity of carbon that is removed from the forest compared to traditional forestry. Due to the fact that the clear cut remains in my study showed a high content of chlorine, there is a risk of corrosion in connection to the incineration of the logging residues in power plants especially at coastal areas/forests. The risk of sulphur -related corrosion is probably rather small, because S concentrations are relatively low in woodchips. The clear cut remains showed rather high heavy metal contents. If the heavy metal contents in this study are representative for the clear cut remains in the coastal forests generally, there might be reason to exert some caution when using the ash for forest fertilizing purposes.
Resumo:
Establishment of Pinus kesiya Roy. ex Gord. plantations in Thailand began in the 1960s by the Royal Forest Department. The aim was to reforest abandoned swidden areas and grasslands in order to reduce erosion and to produce timber and fuel wood. Today there are about 150, 000 ha of P. kesiya plantations in northern Thailand. Most of these plantations cannot be harvested due to a national logging ban. Previous studies have suggested that Pinus kesiya plantations posses a capability as a foster environment for native broadleaved tree species, but little is known about the extent of regeneration in these plantations. The general aim of the study was to clarify the extent of forest regeneration and interactions behind it in Pinus kesiya plantations of the Ping River basin, northern Thailand. Based on the results of this study and previous literature, forest management proposals were produced for the area studied. In four different pine plantation areas, a total of seven plantations were assessed using systematic data collection with clustered circular sample plots. Vegetation and environmental data were statistically analysed, so as to recognise the key factors affecting regeneration. Regeneration had occurred in all plantations studied. Regeneration of broadleaved trees was negatively affected by forest fire and canopy coverage. A high basal area of mature broadleaved trees affected the regeneration process positively. Forest fire disturbance had a strong effect also on plantation structure and species composition. Because of an unclear future forest management setting as regards forest laws in Thailand, a management system that enables various future utilisation possibilities and emphasises local participation is recommended for P. kesiya watershed platations of northern Thailand.
Resumo:
The structure and function of northern ecosystems are strongly influenced by climate change and variability and by human-induced disturbances. The projected global change is likely to have a pronounced effect on the distribution and productivity of different species, generating large changes in the equilibrium at the tree-line. In turn, movement of the tree-line and the redistribution of species produce feedback to both the local and the regional climate. This research was initiated with the objective of examining the influence of natural conditions on the small-scale spatial variation of climate in Finnish Lapland, and to study the interaction and feedback mechanisms in the climate-disturbances-vegetation system near the climatological border of boreal forest. The high (1 km) resolution spatial variation of climate parameters over northern Finland was determined by applying the Kriging interpolation method that takes into account the effect of external forcing variables, i.e., geographical coordinates, elevation, sea and lake coverage. Of all the natural factors shaping the climate, the geographical position, local topography and altitude proved to be the determining ones. Spatial analyses of temperature- and precipitation-derived parameters based on a 30-year dataset (1971-2000) provide a detailed description of the local climate. Maps of the mean, maximum and minimum temperatures, the frost-free period and the growing season indicate that the most favourable thermal conditions exist in the south-western part of Lapland, around large water bodies and in the Kemijoki basin, while the coldest regions are in highland and fell Lapland. The distribution of precipitation is predominantly longitudinally dependent but with the definite influence of local features. The impact of human-induced disturbances, i.e., forest fires, on local climate and its implication for forest recovery near the northern timberline was evaluated in the Tuntsa area of eastern Lapland, damaged by a widespread forest fire in 1960 and suffering repeatedly-failed vegetation recovery since that. Direct measurements of the local climate and simulated heat and water fluxes indicated the development of a more severe climate and physical conditions on the fire-disturbed site. Removal of the original, predominantly Norway spruce and downy birch vegetation and its substitution by tundra vegetation has generated increased wind velocity and reduced snow accumulation, associated with a large variation in soil temperature and moisture and deep soil frost. The changed structural parameters of the canopy have determined changes in energy fluxes by reducing the latter over the tundra vegetation. The altered surface and soil conditions, as well as the evolved severe local climate, have negatively affected seedling growth and survival, leading to more unfavourable conditions for the reproduction of boreal vegetation and thereby causing deviations in the regional position of the timberline. However it should be noted that other factors, such as an inadequate seed source or seedbed, the poor quality of the soil and the intensive logging of damaged trees could also exacerbate the poor tree regeneration. In spite of the failed forest recovery at Tunsta, the position and composition of the timberline and tree-line in Finnish Lapland may also benefit from present and future changes in climate. The already-observed and the projected increase in temperature, the prolonged growing season, as well as changes in the precipitation regime foster tree growth and new regeneration, resulting in an advance of the timberline and tree-line northward and upward. This shift in the distribution of vegetation might be decelerated or even halted by local topoclimatic conditions and by the expected increase in the frequency of disturbances.
Resumo:
The main objective of this study is to evaluate selected geophysical, structural and topographic methods on regional, local, and tunnel and borehole scales, as indicators of the properties of fracture zones or fractures relevant to groundwater flow. Such information serves, for example, groundwater exploration and prediction of the risk of groundwater inflow in underground construction. This study aims to address how the features detected by these methods link to groundwater flow in qualitative and semi-quantitative terms and how well the methods reveal properties of fracturing affecting groundwater flow in the studied sites. The investigated areas are: (1) the Päijänne Tunnel for water-conveyance whose study serves as a verification of structures identified on regional and local scales; (2) the Oitti fuel spill site, to telescope across scales and compare geometries of structural assessment; and (3) Leppävirta, where fracturing and hydrogeological environment have been studied on the scale of a drilled well. The methods applied in this study include: the interpretation of lineaments from topographic data and their comparison with aeromagnetic data; the analysis of geological structures mapped in the Päijänne Tunnel; borehole video surveying; groundwater inflow measurements; groundwater level observations; and information on the tunnel s deterioration as demonstrated by block falls. The study combined geological and geotechnical information on relevant factors governing groundwater inflow into a tunnel and indicators of fracturing, as well as environmental datasets as overlays for spatial analysis using GIS. Geophysical borehole logging and fluid logging were used in Leppävirta to compare the responses of different methods to fracturing and other geological features on the scale of a drilled well. Results from some of the geophysical measurements of boreholes were affected by the large diameter (gamma radiation) or uneven surface (caliper) of these structures. However, different anomalies indicating more fractured upper part of the bedrock traversed by well HN4 in Leppävirta suggest that several methods can be used for detecting fracturing. Fracture trends appear to align similarly on different scales in the zone of the Päijänne Tunnel. For example, similarities of patterns were found between the regional magnetic trends, correlating with orientations of topographic lineaments interpreted as expressions of fracture zones. The same structural orientations as those of the larger structures on local or regional scales were observed in the tunnel, even though a match could not be made in every case. The size and orientation of the observation space (patch of terrain at the surface, tunnel section, or borehole), the characterization method, with its typical sensitivity, and the characteristics of the location, influence the identification of the fracture pattern. Through due consideration of the influence of the sampling geometry and by utilizing complementary fracture characterization methods in tandem, some of the complexities of the relationship between fracturing and groundwater flow can be addressed. The flow connections demonstrated by the response of the groundwater level in monitoring wells to pressure decrease in the tunnel and the transport of MTBE through fractures in bedrock in Oitti, highlight the importance of protecting the tunnel water from a risk of contamination. In general, the largest values of drawdown occurred in monitoring wells closest to the tunnel and/or close to the topographically interpreted fracture zones. It seems that, to some degree, the rate of inflow shows a positive correlation with the level of reinforcement, as both are connected with the fracturing in the bedrock. The following geological features increased the vulnerability of tunnel sections to pollution, especially when several factors affected the same locations: (1) fractured bedrock, particularly with associated groundwater inflow; (2) thin or permeable overburden above fractured rock; (3) a hydraulically conductive layer underneath the surface soil; and (4) a relatively thin bedrock roof above the tunnel. The observed anisotropy of the geological media should ideally be taken into account in the assessment of vulnerability of tunnel sections and eventually for directing protective measures.
Resumo:
Forestry has influenced forest dwelling organisms for centuries in Fennoscandia. For example, in Finland ca. 30% of the threatened species are threatened because of forestry. Nowadays forest management recommendations include practices aimed at maintaining biodiversity in harvesting, such as green-tree retention. However, the effects of these practices have been little studied. In variable retention, different numbers of trees are retained, varying from green-tree retention (at least a few live standing trees in clear-cuts) to thinning (only individual trees removed). I examined the responses of ground-dwelling spiders and carabid beetles to green-tree retention (with small and large tree groups), gap felling and thinning aimed at an uneven age structure of trees. The impacts of these harvesting methods were compared to those of clear-cutting and uncut controls. I aimed to test the hypothesis that retaining more trees positively affects populations of those species of spiders and carabids that were present before harvesting. The data come from two studies. First, spiders were collected with pitfall traps in south-central Finland in 1995 (pre-treatment) and 1998 (after-treatment) in order to examine the effects of clear-cutting, green-tree retention (with 0.01-0.02-ha sized tree groups), gap felling (with three 0.16-ha sized openings in a 1-ha stand), thinning aiming at an uneven age structure of trees and uncut control. Second, spiders and carabids were caught with pitfall traps in eastern Finland in 1998-2001 (pre-treatment and three post-treatment years) in eleven 0.09-0.55-ha sized retention-tree groups and clear-cuts adjacent to them. Original spider and carabid assemblages were better maintained after harvests that retained more trees. Thinning maintained forest spiders well. However, gap felling and large retention-tree groups maintained some forest spider and carabid species in the short-term, but negatively affected some species over time. However, use of small retention-tree groups was associated with negative effects on forest spider populations. Studies are needed on the long-term effects of variable retention on terrestrial invertebrates; especially those directed at defining appropriate retention patch size and on the importance of structural diversity provided by variable retention for invertebrate populations. However, the aims of variable retention should be specified first. For example, are retention-tree groups planned to constitute life-boats , stepping-stones or to create structural diversity? Does it suffice that some species are maintained, or do we want to preserve the most sensitive ones, and how are these best defined? Moreover, the ecological benefits and economic costs of modified logging methods should be compared to other approaches aimed at maintaining biodiversity.
Resumo:
GDP-L-fucose: synthesis and role in inflammation The migration of leukocytes from intravascular locations to extravascular sites is essential to the immune responses. The initial attachment of leukocytes to the endothelium and the rolling step of the leukocyte extravasation cascade are mediated by selectins, a family of cell adhesion molecules on cell surfaces. Selectins are able to recognize glycoproteins and glycolipids containing the tetrasaccharide sialyl Lewis x (sLex, Neu5Acα2-3Galβ1-4(Fucα1-3)GlcNAc). Several glycosyltransferases are involved in the biosynthesis of sLex, fucosyltransferase VII (Fuc-TVII) being the last enzyme to modify the sLex structure. Fuc-TVII transfers L-fucose from GDP-L-fucose to sialylated N-acetyllactosamine. GDP-L-fucose is synthesized in the cytosol via two different metabolic pathways. The major, constitutively active de novo pathway involves conversion of GDP-α-D-mannose to GDP-β-L-fucose. In the alternative salvage pathway, L-fucokinase synthesizes from free fucose L-fucose-1-phosphate, which is further converted to GDP-L-fucose by GDP-L-fucose pyrophosphorylase. GDP-L-fucose is translocated from the cytosol to Golgi for fucosylation via the GDP-fucose transporter. This thesis involved the study of the synthesis of GDP-L-fucose via the salvage pathway: cloning and expression of murine L-fucokinase and GDP-L-fucose pyrophosphorylase. The gene expression levels of these enzymes were found to be relatively high in various tissues; the mRNA levels were highest in brain, ovary and testis. This study also describes molecular cloning of rat fucosyltransferase VII (FUT7) and its expression as a functional enzyme. Gene expression levels of GDP-L-fucose synthesizing enzymes, GDP-fucose transporter and FUT7 were determined in inflamed tissues as well as cancer cells. Our results revealed a clear upregulation of the enzymes involved in the synthesis of GDP-L-fucose via de novo pathway, GDP-fucose transporter and FUT7 in inflamed tissues and in cancer cells. On the contrary, the GDP-L-fucose salvage pathway was found to be irrelevant in inflammation and in tumorigenesis. Furthermore, our results indicated the transcriptional coregulation of Golgi transporters involved in the synthesis of sulfo sLex, i.e. CMP-sialic acid, GDP-fucose and 3 phosphoadenosine 5 -phosphosulfate transporters, in inflammation.
Resumo:
A lack of suitable venous graft material or poor outflow is an increasingly encountered situation in peripheral vascular surgery. Prosthetic grafts have clearly worse patency than vein grafts in femorodistal bypass surgery. The use of an adjuvant arteriovenous fistula (av-fistula) at the distal anastomosis has been postulated to improve the flow and thus increase prosthetic graft patency. In theory the adjuvant fistula might have the same effect in a compromised outflow venous bypass. A free flap transfer also augments graft flow and may have a positive effect on an ischaemic limb. The aim of this study was to evaluate the possible benefit of an adjuvant av-fistula and an internal av-fistula within a free flap transfer on the patency and outcome of an infrapopliteal bypass. The effect of the av-fistula on bypass haemodynamics was also assessed along with possible adverse effects. Patients and methods: 1. A prospective randomised multicentre trial comprised 59 patients with critical leg ischaemia and no suitable veins for grafting. Femorocrural polytetrafluoroethylene (PTFE) bypasses with a distal vein cuff, with or without an adjuvant av-fistula, were performed. The outcome was assessed according to graft patency and leg salvage. 2. Haemodynamic measurements were performed to a total of 50 patients from Study I with a prolonged follow-up. 3. Nine critically ischaemic limbs were treated with a modified radial forearm flap transfer in combination with a femorodistal bypass operation. An internal av-fistula was created within the free flap transfer to increase flap artery and bypass graft flow. 4. The effect of a previous free flap transfer on bypass haemodynamics was studied in a case report. 5. In a retrospective multicentre case-control study, 77 infrapopliteal vein bypasses with an adjuvant av-fistula were compared with matched controls without a fistula. The outcome and haemodynamics of the bypasses were recorded. Main results: 1. The groups with and without the av-fistula did not differ as regards prosthetic graft patency or leg salvage. 2. The intra- and postoperative prosthetic graft flow was significantly increased in the patients with the av-fistula. However, this increase did not improve patency. There was no difference in patency between the groups, even in the extended follow-up. 3. The vein graft flow increased significantly after the anastomosis of the radial forearm flap with an internal av-fistula. 4. A previously performed free flap transfer significantly augmented the flow of a poor outflow femoropedal bypass graft. 5. The adjuvant av-fistula increased the venous infrapopliteal bypass flow significantly. The increased flow did not, however, lead to improved graft patency or leg salvage. Conclusion: An adjuvant av-fistula does not improve the patency of a femorocrural PTFE bypass with a distal vein cuff despite the fact that the flow values increased both in the intraoperative measurements and during the immediate postoperative surveillance. The adjuvant av-fistula increased graft flow significantly also in a poor outflow venous bypass, but regardless of this the outcome was no improved. The adjuvant av-fistula rarely caused adverse effects. In a group of diabetic patients, the flow in a vascular bypass graft was augmented by an internal av-fistula within a radial forearm flap and similarly in a patient with a previous free flap transfer, a high intraoperative graft flow was achieved due to the free flap shunt effect.
Resumo:
This dissertation concerns the Punan Vuhang, former hunter-gatherers who are now part-time farmers living in an area of remote rainforest in the Malaysian state of Sarawak. It covers two themes: first, examining their methods of securing a livelihood in the rainforest, and second looking at their adaptation to a settled life and agriculture, and their response to rapid and large-scale commercial logging. This study engages the long-running debates among anthropologists and ecologists on whether recent hunting-gathering societies were able to survive in the tropical rainforest without dependence on farming societies for food resources. In the search for evidence, the study poses three questions: What food resources were available to rainforest hunter-gatherers? How did they hunt and gather these foods? How did they cope with periodic food shortages? In fashioning a life in the rainforest, the Punan Vuhang survived resource scarcity by developing adaptive strategies through intensive use of their knowledge of the forest and its resources. They also adopted social practices such as sharing and reciprocity, and resource tenure to sustain themselves without recourse to external sources of food. In the 1960s, the Punan Vuhang settled down in response to external influences arising in part from the Indonesian-Malaysian Confrontation. This, in turn, initiated a series of processes with political, economic and religious implications. However, elements of the traditional economy have remained resilient as the people continue to hunt, fish and gather, and are able to farm on an individual basis, unlike neighboring shifting cultivators who need to cooperate with each other. At the beginning of the 21st century, the Punan Vuhang face a new challenge arising from the issue of rights in the context of the state and national law and large-scale commercial logging in their forest habitat. The future seems bleak as they face the social problems of alcoholism, declining leadership, and dependence on cash income and commodities from the market.
Resumo:
In my master's thesis I explore the political significance of logging in Papua New Guinea (PNG). In commercial logging the post-colonial state of PNG, its local communities, transnational companies and non-governmental organizations come interestingly together. The central research questions are what forms of political awareness and mobilization does commercial logging bring up in the small scale communities and how – if at all – does logging change the relationship between these communities and the state of PNG. The thesis is based on three months of ethnographic fieldwork conducted in 2007 in a village located in the East New Britain province of PNG. The village, inhabited mainly by the Mengen people, was an interesting case, because logging operations had been conducted in the area with the permission of the people, while on the other hand some villagers had formed a conservation association of their own. Parliamentary elections were also held in PNG during the time of my fieldwork. During my stay in the village I took part in the village life and conducted interviews. In addition to this, much of my material is based on informal discussions with people. On my way to and from the village I also interviewed several Papua New Guinean NGO-workers in the national and provincial capitals. In my thesis I show that environmental conservation in the village is part of a larger attempt to protect local autonomy, culture and the environment, i.e. it is a ”localistic” movement. Locals supporting conservation, as well as those supporting logging, take actively part in national parliamentary as well as local level politics. In my thesis I have attempted to unpack the notion of ”local” by examining internal power relations of the community and describing various lines of thought and opinions that base on local cultural values. Along with this, commercial logging seems also to elicit the role of the state in two-fold way in East New Britain. On the one hand, the government seeks to use logging roads built by logging companies as the basis of its own national infrastructure, even though the company roads are often of manifestably poor quality and short-lived. On the other hand, problems caused by logging, such as land disputes, create a need among local communities for the state and its services. Central themes in my thesis are the local values invested in the environment, as well as the ways in which the locals produce their environment both conceptually as well as physically. As subsistence farmers the locals depend economically on the condition of their environment. However, the value of the environment goes beyond economical questions. For example, the environment holds proof of the history of the community. Conversely, also the state and companies attempt to conceptualize, modify and administer the environment. This is done through processes such as mapping and road building, both crucial political questions in East New Britain. Here the anthropological discussion about space and place, as well as political geography are central. The diverse ways of conceptualizing the environment, as well as logging, cause often disputes about the ownership of land areas. Because of this I discuss local ways of holding the land communally, as well as PNG's land legislation and ways of dispute management. Land tenure and disputes are political questions that the locals have to deal with and in some cases these questions also create a need for the judiciary system of the state. The disputes affect also political activity, which I discuss at some length in my thesis as well. Interestingly, the locals, regardless of their political views and affiliations, establish transnational connections ranging from NGOs to government departments and multinational companies.
Resumo:
Metsäsuunnittelussa tarvittavan metsävaratiedon keräämisessä ollaan Suomessa siirtymässä kuvioittaisesta arvioinnista laserkeilaus- ja ilmakuvapohjaiseen kaukokartoitukseen. Tämän tutkimuksen tarkoitus oli selvittää kuvion kokonaistilavuuden ja läpimittajakauman ennustamisen tarkkuus koealan metsikkö- ja puustotunnuksista MSN-, PRM-, ML- ja FMM-menetelmiä sekä Weibull-jakaumaa hyödyntäen seuraavilla tavoilla: 1. PRM-menetelmällä hilatasolla, 2. PRMmenetelmällä kuviotasolla, 3. ML-menetelmällä hilatasolla ja 4. ML-menetelmällä kuviotasolla. Lisäksi kuvion kokonaistilavuuden ennustamisen tarkkuus selvitettiin hyödyntäen kuviolle tuotettua runkolukusarjaa. Tulokset laskettiin puulajikohtaisesti männylle, kuuselle, koivulle ja muille puulajeille. Puulajien tulokset laskettiin kuviotasolla yhteen. Lisäksi selvitettiin menetelmien laskenta-ajan ja tallennustilan tarve. Tutkimuksen aineistona käytettiin Hämeen ammattikorkeakoulun Evon toimipisteen metsistä mitattuja kiinteäsäteisiä ympyräkoealoja, joita oli 249 kappaletta. Hakkuukoneella mitattiin 12kuvion, joiden pinta-alat vaihtelivat välillä 0,2 – 1,94 hehtaaria, puustotiedot. Aluepohjaisen laserkeilausaineiston pulssin tiheys oli 1,8/m2 ja ilmakuvien pikselikoko 0,5 metriä. Kuvion kokonaistilavuus ennustettiin tai estimoitiin laserkeilaus- ja ilmakuva-aineiston piirteiden avulla koealojen puustotunnuksista. Tulokset laskettiin erikseen kaikille kuvioille ja kuvioille, joiden pinta-ala oli yli 0,5 hehtaaria. Yli 0,5 hehtaarin kuvioita oli 8 kappaletta. Kuvion hilojen naapureina käytettiin 1 - 10 koealaa. Menetelmästä ja naapurien määrästä riippuen kokonaistilavuuden suhteellinen RMSE ja harha vaihtelivat välillä 20,76 – 52,86 prosenttia ja -12,04 – 46,54 prosenttia. Vastaavat luvut yli 0,5 hehtaarin kuvioilla olivat 6,74 – 59,41 prosenttia ja -8,04 – 49,59 prosenttia. Laskenta-aika vaihteli menetelmien ja käytettyjen naapurien määrän mukaan voimakkaasti. Kehittyneemmällä ohjelmoinnilla ja ohjelmistolla laskenta-ajat voivat laskea merkittävästi. Tallennustila ei testatuilla menetelmillä ole rajoittava tekijä laajassakaan mittakaavassa. Läpimittajakauman perusteella PRM-menetelmä ennustaa puulajille erittäin kapean läpimittajakauman, jos koeala koostuu vain muutamasta lähes samankokoisesta puusta. Tämä vaikutti tuloksiin erityisesti menetelmällä PRM2.
Resumo:
Forest certification has been put forward as a means to improve the sustainability of forest management in the tropical countries, where traditional environmental regulation has been inefficient in controlling forest degradation and deforestation. In these countries, the role of communities as managers of the forest resources is rapidly increasing. However, only a fraction of tropical community forests have been certified and little is known about the impacts of certification in these systems. Two areas in Honduras where community-managed forest operations had received FSC certifications were studied. Río Cangrejal represents an area with a longer history of use, whereas Copén is a more recent forest operation. Ecological sustainability was assessed through comparing timber tree regeneration and floristic composition between certified, conventionally managed and natural forests. Data on woody vegetation and environmental conditions was collected within logging gaps and natural treefall gaps. The regeneration success of shade-tolerant timber tree species was lower in certified than in conventionally managed forests in Río Cangrejal. Furthermore, the floristic composition was more natural-like in the conventionally managed than the certified forests. However, the environmental conditions indicated reduced logging disturbance in the certified forests. Data from Copén demonstrated that the regeneration success of light-demanding timber species was higher in the certified than the unlogged forests. In spite of this, the most valuable timber species Swietenia macrophylla was not regenerating successfully in the certified forests, due to rapid gap closure. The results indicate that pre-certification loggings and forest fragmentation may have a stronger impact on forest regeneration than current, certified management practices. The focus in community forests under low-intensive logging should be directed toward landscape connectivity and the restoration of degraded timber species, instead of reducing mechanical logging damage. Such actions are dependent on better recognition of resource rights, and improving the status of small Southern producers in the markets of certified wood products.
Resumo:
Linear optimization model was used to calculate seven wood procurement scenarios for years 1990, 2000 and 2010. Productivity and cost functions for seven cutting, five terrain transport, three long distance transport and various work supervision and scaling methods were calculated from available work study reports. All method's base on Nordic cut to length system. Finland was divided in three parts for description of harvesting conditions. Twenty imaginary wood processing points and their wood procurement areas were created for these areas. The procurement systems, which consist of the harvesting conditions and work productivity functions, were described as a simulation model. In the LP-model the wood procurement system has to fulfil the volume and wood assortment requirements of processing points by minimizing the procurement cost. The model consists of 862 variables and 560 restrictions. Results show that it is economical to increase the mechanical work in harvesting. Cost increment alternatives effect only little on profitability of manual work. The areas of later thinnings and seed tree- and shelter wood cuttings increase on cost of first thinnings. In mechanized work one method, 10-tonne one grip harvester and forwarder, is gaining advantage among other methods. Working hours of forwarder are decreasing opposite to the harvester. There is only little need to increase the number of harvesters and trucks or their drivers from today's level. Quite large fluctuations in level of procurement and cost can be handled by constant number of machines, by alternating the number of season workers and by driving machines in two shifts. It is possible, if some environmental problems of large scale summer time harvesting can be solved.