Gregory Taff

Research Scientist

(+47) 991 51 528
gregory.taff@nibio.no

Place
Ås R9

Visiting address
Raveien 9, 1430 Ås

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Abstract

Species invasions are a global problem that often must be dealt with at local levels. Addressing this problem generally requires mixing strategies, policies, and technologies and working with multiple stakeholder groups. Invasive plant species can cause various societal problems, such as reducing biodiversity by outcompeting native plants. One example of an invasive plant species that has proven very difficult to control is the giant hogweed (Norw. Kjempebjørnekjeks; Heracleum mantegazzianum).

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Abstract

This chapter presents an analysis of land cover changes in Eastern Europe between 1990 and 2006, assessed using CORINE (Co-ORdination of INformation on the Environment) Land Cover (CLC) datasets. The plethora of potential land cover change categories were condensed into seven categories of major land use change processes: urbanization, agricultural intensification, agricultural extensification, afforestation, deforestation, construction and management of water bodies, and other changes. The amounts of each change category and their spatial distributions are summarized, and the change categories were also mapped to show the relative amounts of change (per 3 × 3 km2) between 1990 and 2000 and between 2000 and 2006. The results showed that while more afforestation than deforestation was observed in the first period, the reverse was true in the second period, when deforestation outpaced afforestation. Urbanization and suburbanization were major processes in Eastern Europe, particularly around existing major cities, and the speed of this process generally increased from the first to the second period. Both the intensification and extensification of agriculture were common during both periods, but a larger effect was observed in the first period. Overall, land use changes were highest in central Europe and the Baltic countries and lowest in southeast Europe.

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Abstract

In the city of Tromsø in northern Norway, invasive Tromsø palm (Norwegian: Tromsøpalme; English: Persian hogweed) is widespread. Although Tromsø palm has negative impacts on biodiversity and contains a phototoxic sap that burns human skin, it is also considered to be a local symbol of Tromsø city and is appreciated by many inhabitants. This study examined private landowners’ characteristics, perceptions, and landowners’ regulation of invasive Tromsø palm on their parcels on Tromsø Island in 2012 (vegetation season: May–September) to provide information concerning which landowner groups could be assisted by official regulation. Eleven key informants and 17 landowners were interviewed. Afterward, Tromsø palm on Tromsø Island was mapped using aerial photos and street-level photos from Google Maps®/Google Street View® and fieldwork verification. This distribution map was superimposed on a property map in a geographic information system to produce a map showing private parcels that contained Tromsø palm and associated neighboring parcels that did not contain Tromsø palm. Questionnaires were mailed to the 441 owners of the selected parcels, and 199 of the returned questionnaires were analyzed. Tromsø palm was more likely to be fully regulated/absent on a parcel that was inhabited (particularly if the owner lived on-site) and less likely to be fully regulated/absent if the parcel was jointly managed by several households. These findings indicate that authorities could focus their management efforts on supporting regulation efforts of those private landowners who own currently uninhabited or rented-out parcels and landowners of parcels jointly managed by several households. Furthermore, those landowners who found regulation measures against the plant on Tromsø Island important tended to have partly or fully regulated Tromsø palm on their plots. This might imply that information campaigns from authorities might encourage more landowners to regulate Tromsø palm.

Abstract

The aims of this study were: (1) to assess the trends of climatic variables in two contrasting geographical locations: central Poland and northern Norway; and (2) to evaluate the influence of the detected trends on timothy yields. This grass species was selected for its high importance for forage production in Norway as well as in Poland. For the assessment of climate trends, historical meteorological data, which cover time series from 1985 onwards, were used. Trends of various climate condition indicators were investigated. Data on timothy yields were collected beginning in the 1990s for Brody in Poland from cultivar testing experiments and Holt in Norway by the national cultivar-testing program. The results indicated that in central Poland air temperature in specific months significantly decrease the annual yield of timothy while in northern Norway many climatic variables, such as earlier start and prolonged length of growing season, may have a slightly positive impact on timothy productivity.

Abstract

Grasslands are significant as a source of forage for animal production, but are also important in many ecological functions. To be able to analyse changes in environmental conditions of grasslands, monitoring of grassland areas using remote sensing is an important task. Studying changes in environmental condition over time and space in grasslands has been the subject of research at different scales. Such an example is the Polish-Norwegian Research Project FINEGRASS „Effect of climatic changes on grassland growth, its water conditions and biomass’. In situ measured soil-vegetation parameters and satellite observations have been combined and analysed to quantify the spatial and temporal variability of grassland conditions, as reflected in variations of vegetation surface temperature, soil moisture, and biomass. Results show a significant trend of increasing grassland surface temperature in Poland, based on AVHRR satellite data; a positive significant relationship between the (April-September) standardized precipitation evapotranspiration index (SPEI) and grass yields in Poland; northern Norway has shown trends towards warmer springs and autumns since 1991, and significant trends towards earlier snowmelt and green-up on test fields in northern Norway.

Abstract

Background & Aim: Land-use regimes and their changes, as well as landscape heterogeneity are key determinants of the distribution and composition of species in cultural landscapes. In European agricultural landscapes, habitat loss due to both abandonment and intensification of agriculture fields are major causes for the decline of species diversity. Landscapes that are diverse in habitats and species are important to maintain basic ecosystem functions and services as, for instance, pollination or habitat preservation. In Norway, semi-natural species-rich habitats, such as agricultural grasslands, often occur in mosaics with forests and crop fields. This research studies key information for design of conservation plans focused on these habitats, addressing how landscape structure and land-use history affect the distribution, richness and composition of species in species-rich grasslands across geographical regions. Material & Methods: We recorded vegetation (species occurrence and cover) in agricultural grasslands with varying intensity and type of use from 569 plots of 8 x 8 m size systematically distributed throughout Norway (from 64 to 78 °N latitude). To identify the most important driving factors of species diversity and composition we explored the combined effects of historic and current land-use and the spatial landscape configuration of nearby land cover types (e.g. minimum distance to or area of neighbouring wetland, forest, cultivated land) taking into account the effects of grazing, elevation, and moisture conditions. Non-metrical multidimensional scaling (NMDS) was applied to identify the most important drivers of species composition. We used Generalized Additive Mixed Models to test the relationship of these drivers with patterns in species richness. Main results & Interpretations: NMDS revealed species composition to be explained most by the distance to surface cultivated land and transportation corridors (r=0.905, p<0.001 and r=-0.982, p<0.001; 1. NMDS axis) as well as shape of the patch in which the vegetation plot is embedded (patch shape) and grazing intensity (r=0.988, p<0.001 and r=-0.952, p<0.001; 2. NMDS axis). Observed patterns in species richness were statistically significantly linked to the combined effects of elevation, grazing intensity, historical land-use, patch shape, distance to transportation corridors and forest, and area of nearest wetland. Our results demonstrate the importance of a variety of factors influencing the species composition and richness in Norwegian grasslands. We found that both the landscape element harbouring the observed plot and also the surrounding landscape structure and intensity of land-use are important determinants of species diversity. The fact that distance to more intensively managed agricultural land is one of the strongest explanatory facts signals how effects of agricultural management practices reaches outside the field itself and into adjacent landscape elements. This suggests that the entire landscape needs to be taken into consideration when management of a particular habitat patch is planned.

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Abstract

Land-use and land-cover change (LULCC), especially those caused by human activities, is one of the most important components of global environmental change (Jessen 3rd edition: 1-526 2005). In this study the effects of geographic and demographic factors on LULCC are analyzed in northeastern Latvia using official estimates from census and vital statistics data, and using remotely sensed satellite imagery (Landsat Thematic Mapper) acquired from 1992 and 2007. The remote sensing images, elevation data, in-situ ground truth and ground control data (using GPS), census and vital statistics data were processed, integrated, and analyzed in a geographic information system (GIS). Changes in six categories of land-use and land-cover (wetland, water, agriculture, forest, bare field and urban/suburban) were studied to determine their relationship to demographic and geographic factors between 1992 and 2007. Supervised classifications were performed on the Landsat images. Analysis of land cover change based on “change-to” categories between the 1992 and 2007 images revealed that changes to forest were the most common type of change (17.1% of pixels), followed by changes to agriculture (8.6%) and the fewest were changes to urban/suburban (0.8%). Integration of population data and land-cover change data revealed key findings: areas near to roads underwent more LULCC and areas far away from Riga underwent less LULCC. Range in elevation was positively correlated with all LULCC categories. Population density was found to be associated with most LULCC categories but the direction of effect was scale dependent. This paper shows how socio-demographic data can be integrated with satellite image data and cartographic data to analyze drivers of LULCC at multiple spatial scales.

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Abstract

Over the last two decades West Nile Virus (WNV) has been responsible for significant disease outbreaks in humans and animals in many parts of the World. Its extremely rapid global diffusion argues for a better understanding of its geographic extent. The purpose of this inquiry was to explore spatio-temporal patterns of WNV using geospatial technologies to study populations of the reservoir hosts, vectors, and human hosts, in addition to the spatio-temporal interactions among these populations. Review of the recent literature on spatial WNV disease risk modeling led to the conclusion that numerous environmental factors might be critical for its dissemination. New Geographic Information Systems (GIS)-based studies are monitoring occurrence at the macro-level, and helping pinpoint areas of occurrence at the micro-level, where geographically-targeted, species-specific control measures are sometimes taken and more sophisticated methods of surveillance have been used.