Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2012
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Forfattere
Merethe Lerfald Gudbrand Lien Per Kristian Alnes Roald Sand Kristin Stokke Folstad Siv Karin Paulsen RyeSammendrag
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Forfattere
Gudbrand Lien Per Kristian Alnes Merethe Lerfald Roald Sand Kristin Stokke Folstad Siv Karin Paulsen RyeSammendrag
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Sammendrag
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Sammendrag
The purpose of the study was to explore and compare three different methods for modelling potential natural vegetation (PNV), a hypothetic natural state of vegetation that shows nature's biotic potential in the absence of human influence and disturbance. The vegetation was mapped in a south-central Norwegian mountain region, in a 34.2 km2 area around the village of Beitostølen, in 2009. The actual vegetation map (AVM) formed the basis for the development of PNV using three different modelling methods: (1) an expert-based manual modelling (EMM), (2) rule-based envelope GIS-modelling (RBM), and (3) a statistical predictive GIS-modelling method (Maxent). The article shows that the three modelling methods have different advantages, challenges and preconditions. The findings indicate that: (1) the EMM method should preferably be used only as a supplementary method in highly disturbed areas, (2) both the RBM and the Maxent methods perform well, (3) RBM performs especially well, but also Maxent are more objective methods than EMM and they are much easier to develop and re-run after model validation, (4) Maxent probably underestimates the potential distribution of some vegetation types, whereas RBM overestimates, (5) the Maxent output is relative probabilities of distribution, giving higher model variation than RBM.
Sammendrag
Pilgrims travel along the main reopened St Olav pilgrim routes in Norway and visit a variety of cultural heritage types. These routes are part of a value creation programme, in which the management authorities try to increase the numbers of pilgrims. At the same time, forest regrowth is reported to reduce the landscape experience of pilgrims and to biophysically change the cultural heritage sites. However, no studies have been reported on the spatial encroachments of forests along the pilgrim routes. The purpose of this study is to analyse where forest regrowth along the main reopened pilgrim routes in Norway will appear, given the present climatic conditions, and to assess the spatial overlap of future forest regrowth with cultural heritage sites. A potential forest model and a cultural heritage sites database were combined with several baseline geographical data layers and spatially joined in geographical information systems. The results show that most of the future forest regrowth will appear in mountainous parts of the pilgrim routes, whereas many hunting sites, tradition sites and other cultural heritage sites will be overgrown by young forests. Therefore, management efforts to keep the main pilgrim routes open need to be strengthened and directed towards future risks.
Sammendrag
Landscapes reflect both historic and current cultural and socio-economic activities of human societies. Accordingly, as human societies change, the landscape changes as well. Agriculture is the main driver of landscape changes in the Czech Republic. Therefore, it is necessary to devote special attention to agricultural practices and define simple but effective steps to improve landscape mosaics towards a sustainable development. In this study, regional information about historic changes in landscape structure was studied to (1) identify the trends in land use/cover development since 1940 to 2010 and (2) determine the impact of land use change on the resulting heterogeneity of the landscape. The overall purpose was to find areas of compromise which would allow strengthening of landscape structure and thus stabilize its functions. We specified trends of land use/cover development in 15 catchments with varying agriculture intensity. We digitalized aerial photographs from 1940, 1960, and 1990 and orthophotomaps from 2010. Then, we used a heterogeneity index to define landscape heterogeneity in all catchments and time horizons. The results of our research confirmed increasing tillage effort in intensively cultivated areas, support of secondary succession processes in marginalized areas, and overall increase in forest area. Our study found that simplification and homogenization of the landscape mosaic took place in all studied areas, with the steepest decline found in areas with high agriculture intensity. However, linear vegetation proved to be a suitable starting point for a targeted effort to increase heterogeneity and thus seemed to be crucial for sustainable development of landscape functions in agroecosystems.
Forfattere
Daniela Sauer Peter Finke Rolf Sørensen Ragnhild Sperstad Isabelle Schülli-Maurer Helge I. Høeg Karl StahrSammendrag
The first results of modeling soil development in marine sediments in S Norway using the model SoilGen are compared to measured properties of two soil chronosequences, on the western and eastern side of Oslofjord, respectively. The aim of this work is to test how well soil development under well-defined environmental conditions can be modeled. Such testing reveals to what degree soil-forming processes are understood, allowing formulation of adequate calculations reflecting these processes. The model predicts particle size distribution reasonably well, although clay depletion in the upper parts of the soils as a result of clay migration is overestimated. The model tends to underestimate contents of organic carbon and CEC in the A horizons: below, modeled CEC matches well with measured CEC. Base saturation is overestimated in the upper 40 cm and underestimated below. Apparently, leaching of bases proceeds less rapidly in reality than is predicted by the model, due to strong soil structure of the B horizons, causing preferential flow and base leaching around the aggregates, whereas bases inside the aggregates are only slightly affected by leaching. Difficulties and possibilities for improvements are identified, some related to model input data and some to the model itself. Input data could be improved by determining the amounts of organic carbon in organic surface horizons and by quantifying effects of bioturbation. A big challenge is the implementation of soil structure formation in the model. Quantitative data on the development of soil structure with time that can be included in a model are required. Amounts, distribution and connectivity of macro pores need to be defined for each stage of soil development, and zones of low and high base leaching need to be distinguished in the model for each time step. The long-term aim of this work is to model soil development with different sets of soil-forming factors, e.g. different climatic conditions in order to reliably predict soil development under different climate scenarios and related sets of soil-forming factors. The results of the first model runs and the identified possible improvements suggest that this aim is generally achievable.
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