Browsing by Subject "modelling"

Sort by: Order: Results:

Now showing items 21-26 of 26
  • Nystedt, Ari (Helsingin yliopisto, 2019)
    The modern, intensive silviculture has affected negatively to the grouses. Main reasons are changes in the ground vegetation and decreasing proportion of blueberry. Main features for grouse habitats are variety in the forest cover and protection from the understorey. In managed forests fluctuation can be increased via thickets. Thicket size varies from couple of trees to approximately two ares. Tickets are uncleared patches containing trees in various sizes. To highlight grouses via game-friendly forest management, information about the habitat is required in the forest site and broader area. Observations about the grouses in the forest site and the information about capercaillie’s lekking sites, willow grouse’s habitats and the wintering areas have been beneficial. Information about grouse densities and population’s fluctuations has been gathered via game triangles. Guide books about game husbandry contain information about grouse habitats and thicket characteristics. The aim of this study was to investigate, whether it is possible to model suitable thickets and grouse habitats with open GIS (Geographical Information Systems) material via GIS- analyses. Examined grouse species in modelling were capercaillie, black grouse and hazel grouse. Weighted Overlay was done with ArcMap- software. Suitable thickets and habitats were examined in the whole research area and in suitable figures. Based on the results of the analysis, theme maps were made to represent the research area’s suitability for thickets and grouse habitats. The needed material for the thickets was collected and GIS- analyses were made in the research area in Tavastia Proper, Hausjärvi. For the research, 12 one-hectare squares were created. Together 45 suitable areas for thickets were charted via field inventory. After the field inventory and GIS- analyses, the results were compared. Key figures from the tickets were number of the thickets, areas, distance to the nearest thicket, averages and standard deviations. Statistical methods were applied to examine possible statistically significant differences between areas and between distances to the nearest thicket. Performed tests were One-Way ANOVA and Kruskall-Wallis. Grouse habitat’s tree characteristics were examined with up-to-date forest management plan. Tree characteristics were examined from 17 suitable figures, covering total area of 42,6 hectares. In field inventory, the average amount of found thickets in research grid was 3,8 and with modelling 1,4. The average area of thicket was 76,9 m2 in field inventory and 252 m2 in modelling. The average distance between thickets was 12,6 meters in field inventory and 24,8 meters with modelling. In field inventory thickets covered approximately 2,9 percent and modelled 3,6 percent of the research grid’s total area. According to statistical analyses, there was statistically significant difference between the inventory method to the total thicket area and distance to the nearest thicket. According to the modelling and forest management plan, capercaillie’s habitats were located in mature pine stands. Black grouse habitats were located in spruce dominated, young forest stands. Hazel grouse habitats included high proportion of broad-leaved trees, which were visible in ecotones between forest and field. Common for capercaillie, black grouse and hazel grouse habitats were minor surface area and mosaic-like structure. As a result, thickets and grouse habitats can be modeled with open GIS-material. However, modelling requires knowing the characteristics of thickets and examined species. With weighted overlay thickets were not found in areas where canopy density and spruce volume were naturally low. Research is needed to verify thicket’s occupation with trail cameras. The ecological impacts on the research area by saving thickets require evaluation.
  • Saarilahti, M. (2002)
    A simple EXCEL-programmed forwarder model to estimate the technical and ecological mobility of a forwarder on slopes.
  • Canals, Miquel; Pham, Christopher K.; Bergmann, Melanie; Gutow, Lars; Hanke, Georg; van Sebille, Erik; Angiolillo, Michela; Buhl-Mortensen, Lene; Cau, Alessando; Ioakeimidis, Christos; Kammann, Ulrike; Lundsten, Lonny; Papatheodorou, George; Purser, Autun; Sanchez-Vidal, Anna; Schulz, Marcus; Vinci, Matteo; Chiba, Sanae; Langenkämper, Daniel; Möller, Tiia; Nattkemper, Tim W.; Ruiz, Marta; Suikkanen, Sanna; Woodall, Lucy; Fakiris, Elias; Eugenia, Maria; Jack, Molina; Giorgetti, Alessandra (IOP Publishing, 2021)
    Environmental Research Letters 16: 023001
    The seafloor covers some 70% of the Earth’s surface and has been recognised as a major sink for marine litter. Still, litter on the seafloor is the least investigated fraction of marine litter, which is not surprising as most of it lies in the deep sea, i.e. the least explored ecosystem. Although marine litter is considered a major threat for the oceans, monitoring frameworks are still being set up. This paper reviews current knowledge and methods, identifies existing needs, and points to future developments that are required to address the estimation of seafloor macrolitter. It provides background knowledge and conveys the views and thoughts of scientific experts on seafloor marine litter offering a review of monitoring and ocean modelling techniques. Knowledge gaps that need to be tackled, data needs for modelling, and data comparability and harmonisation are also discussed. In addition, it shows how research on seafloor macrolitter can inform international protection and conservation frameworks to prioritise efforts and measures against marine litter and its deleterious impacts.
  • Raukunen, Osku; Vainio, Rami; Tylka, Allan J.; Dietrich, William F.; Jiggens, Piers; Heynderickx, Daniel; Dierckxsens, Mark; Crosby, Norma; Ganse, Urs; Siipola, Robert (2018)
    Solar energetic particles (SEPs) constitute an important component of the radiation environment in interplanetary space. Accurate modeling of SEP events is crucial for the mitigation of radiation hazards in spacecraft design. In this study we present two new statistical models of high energy solar proton fluences based on ground level enhancement (GLE) observations during solar cycles 19-24. As the basis of our modeling, we utilize a four parameter double power law function (known as the Band function) fits to integral GLE fluence spectra in rigidity. In the first model, the integral and differential fluences for protons with energies between 10MeV and 1 GeV are calculated using the fits, and the distributions of the fluences at certain energies are modeled with an exponentially cut-off power law function. In the second model, we use a more advanced methodology: by investigating the distributions and relationships of the spectral fit parameters we find that they can be modeled as two independent and two dependent variables. Therefore, instead of modeling the fluences separately at different energies, we can model the shape of the fluence spectrum. We present examples of modeling results and show that the two methodologies agree well except for a short mission duration (1 year) at low confidence level. We also show that there is a reasonable agreement between our models and three well-known solar proton models (JPL, ESP and SEPEM), despite the differences in both the modeling methodologies and the data used to construct the models.
  • Nagatsu, Michiru; MacLeod, Miles (2018)
    In this paper we take a close look at current interdisciplinary modeling practices in the environmental sci- ences, and suggest that closer attention needs to be paid to the nature of scientific practices when investigating and planning interdisciplinarity. While interdisciplinarity is often portrayed as a medium of novel and trans- formative methodological work, current modeling strategies in the environmental sciences are conservative, avoiding methodological conflict, while confining interdisciplinary interactions to a relatively small set of pre-existing modeling frameworks and strategies (a process we call crystallization). We argue that such prac- tices can be rationalized as responses in part to cognitive constraints which restrict interdisciplinary work. We identify four salient integrative modeling strategies in environmental sciences, and argue that this crystalliza- tion, while contradicting somewhat the novel goals many have for interdisciplinarity, makes sense when con- sidered in the light of common disciplinary practices and cognitive constraints. These results provide cause to rethink in more concrete methodological terms what interdisciplinarity amounts to, and what kinds of inter- disciplinarity are obtainable in the environmental sciences and elsewhere.