Karl H. Thunes

Research Scientist

(+47) 456 00 856
karl.thunes@nibio.no

Place
Ås H8

Visiting address
Høgskoleveien 8, 1433 Ås

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Abstract

Herbivory by insects and mites on physic nut (Jatropha curcas L.) seedlings was investigated and compared with irrigation in the semi-arid Sahelian Niger, utilizing a randomized complete block design experiment. Three water treatment protocols were applied and the types of damage were recorded. Less than 5% of the seedlings died during the 10-month trial period with sap suckers causing the most damage on the surviving plants. Plants with high production of biomass and leaf cover (foliage) were most strongly positively correlated with irrigation and were also the plants that endured the highest degree of herbivory. The low dieback may indicate that defence mechanisms counteract seedling herbivory and that drought-stressed plants invest more in their defence mechanism system than vital plants.

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Abstract

The collapse of the Soviet Union in the Central Asian countries has led to enormous challenges for them ensuring a sustainable environment. Weak economies, weak institutions and lack of environmental sciences expertise were important reasons for the Norwegian support to the environmental sector in this region. The State Forest Service of the Kyrgyz Republic and the Norwegian Forestry Group initiated the TEMP project, later renamed TEMP-CA, in the Kyrgyz Republic in 2004. TEMP-activities in the Republic of Tajikistan were included in 2007 and in the Republic of Uzbekistan from 2008. In 2008, as a spin-off of TEMP-CA, the Ahangaran Forest Damage Project was initiated realizing that the Juniper forests surrounding the town of Angren were under environmental constrain, possibly due to massive industrial activities....

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Abstract

The pinewood nematode (PWN) is one of the worst tree-killing exotic pests in East-Asian countries. The first European record of establishment in Portugal in 1999 triggered extensive surveys and contingency plans for eradication in European countries, including immediate removal of large areas of conifer host trees. Using Norway as an example, we applied a simulation model to evaluate the chance of successful eradication of a hypothetical introduction by the current contingency plan in a northern area where wilting symptoms are not expected to occur. Despite a highly variable spread of nematode infestations in space and time, the probability of successful eradication in 20 years was consistently low (mean 0.035, SE 0.02). The low success did not change significantly by varying the biological parameters in sensitivity analyses (SA), probably due to the late detection of infestations by the survey (mean 14.3 years). SA revealed a strong influence of management parameters. However, a high probability of eradication required unrealistic measures: achieving an eradication probability of 0.99 in 20 years required 10,000 survey samples per year and a host tree removal radius of 8,000 m around each detection point.

Abstract

Arthropods were collected by fogging the canopy of Scots pine Pinus sylvestris selected from a 2 km2 boreal forest area in Sigdal, Norway with the overall purpose to examine whether there were faunal differences in the representation of arthropods among mature and old trees, and specifically for this paper, the biting midges (Ceratopogonidae). Target trees were chosen as pairs, one mature (70-110 years) and one old (250 years or older) tree from six different stands. All knock-down treatments were performed in June and July 1999, before dawn and after a dry and windless night. Knocked-down arthropods were collected in plastic funnels placed systematically on the ground. Funnels remained in place for circa one hour after treatment. Among the 61 species records new to Norway, the most frequently encountered taxon of invertebrates was Diptera, and the family of biting midges, Ceratopogonidae, comprised 30 of 61 (49%) of all new records, compared with the overall species numbers showing 40 biting midges of 193 recorded species (21%). Among the Ceratopogonidae new to Norway, two species new to science and two first records from Europe were found. Coleman rarefaction curves were constructed by running 500 iterations without replacements using EstimateS and showed that there were significantly more new records of Diptera in old trees in comparison with mature trees. A similar pattern of significance (by comparing standard deviations estimated by EstimateS) was found for Diptera when Ceratopogonidae was excluded. New species records of Ceratopogonidae were more common in old trees than in mature trees, although not significantly so. No predominance of new records in old trees was found for arthropods other than Diptera. Old trees are rare and may provide a variety of resources (e.g. resting sites, places to over-winter, hiding places, sites for oviposition, larval habitat, etc.) that are rarely found in younger trees. Thus, the high number of new species records probably result from studying a whole arthropod taxon (Diptera) in a part of a forest ecosystem (canopies) with a suite of microhabitats (old pine trees) that in combination has been poorly investigated earlier.

Abstract

Results from a literature review on pinewood ecology, silviculture, genetics, aspects of history and forest resources of Scots pine (Pinus sylvestris L.) in western Norway are presented. The pinewoods cover 40 per cent of the forested land, 0.31 million ha. During the last 75 years, the area has increased by 17 per cent and the growing stock has risen from 10 to 34 million m3. The impact of man in previous times was very marked, and has had a significant influence on the present forest conditions. The pronounced climatic gradients mixed with the topographic variation - from the coastal plains via the fjord systems to the high mountains - is reflected in rather steep gradients in the pine forest vegetation. Various floristic elements can be distinguished, from oceanic via the suboceanic in the outer islands to the thermophytic, boreonemoral and boreal elements in the inner fjord districts and valleys. The introduction of spruce (Picea spp.) plantations on 10-15 per cent of former native pine forests has not negatively affected the bird fauna at the landscape scale. Although not particular species rich, the pine forests harbour species usually not found in other forest types. So far, most work in the field of silviculture and forest ecology in the pinewoods of West Norway has been in the form of case studies. Implications of the results for forestry in the region are briefly discussed.

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Abstract

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Abstract

We fogged trees in two pine dominated forests in Norway with a synthetic pyrethroid in order to compare the canopy-dwelling fauna of arthropods between costal (Kvam) and boreal (Sigdal) sites and between old (250-330 years) and mature (60-120 years) trees at Sigdal. Almost 30,000 specimens were assigned to 510 species; only 93 species were present at both sites. Species diversity, as established by rarefaction, was similar in old and mature trees. However, the number of species new to Norway (including nine species new to science) was significantly higher in the old trees. We suggest that the scarcity of old trees, habitat heterogeneity and structural differences between old and mature trees may explain these patterns. Productivity and topographic position at the site of growth explained the between-tree variation in species occurrence for the more abundant species, which were mainly Collembola and Oribatida. Species diversity was similar at the boreal and coastal sites, but there were clear differences in species composition

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Abstract

The beetle fauna of 299 sporocarps of the bracket fungus Fomitopsis pinicola in a 200 ha spruce forest in southeastern Norway was investigated in relation to sporocarp, tree and forest variables. The sporocarps contained 36 species of beetles, of which six species are on the Norwegian Red List. Of 12,373 individual beetles collected, 91 % were Cis glabratus. Plots of species accumulation curves suggested that there may be more than 60 beetle species present in F. pinicola in the area, but that probably all the specialist Ciidae were found. The major factor influencing beetle diversity turned out to be the level of dead wood at and in the vicinity of the sampling site, with a higher number of species per unit volume of sporocarps in areas with high levels of dead wood. There were also significantly more red-listed species in those areas. Analysing the species occurrence with stepwise logistic regression, we show preferential habitat selection of the six most abundant species of Ciidae. Conservation of beetles associated with bracket fungi using amount of dead wood as a surrogate measurement is discussed.