Jostein Gohli
Forsker
Biografi
Jeg forsker på skadeinsekter i skog og benytter kvantitative metoder og romlige analyser. For tiden har stor granbarkbille og insekts-karanteneskadegjørere særlig fokus i mitt arbeid. Jeg startet ved NIBIO i 2021, og har tidligere jobbet ved Forsvarets forskningsinstitutt, NTNU, Universitetsmuseet i Bergen og Naturhistorisk museum i Oslo. Tidligere jobbet jeg i hovedsak med evolusjonsbiologi og metagenomikk.
Forfattere
Volkmar Timmermann Paul Eric Aspholm Isabella Børja Nicholas Clarke Carl Frisk Jostein Gohli Jane Uhd Jepsen Paal Krokene Nina Elisabeth Nagy Christo Nikolov Jørn-Frode Nordbakken Joyce Machado Nunes Romeiro Sverre Solberg Halvor Solheim Arvid Svensson Jozef Vakula Ole Petter L. Vindstad Bjørn Økland Wenche AasSammendrag
Skogens helsetilstand påvirkes i stor grad av klima og værforhold, enten direkte ved tørke, frost og vind, eller indirekte ved at klimaet påvirker omfanget av soppsykdommer og insektangrep. Klimaendringene og den forventede økningen i klimarelaterte skogskader gir store utfordringer for forvaltningen av framtidas skogressurser. Det samme gjør invaderende skadegjørere, både allerede etablerte arter og nye som kan komme til Norge i nær framtid. I denne rapporten presenteres resultater fra skogskadeovervåkingen i Norge i 2023 og trender over tid for følgende temaer: (i) Landsrepresentativ skogovervåking; (ii) Intensiv skogovervåking; (iii) Overvåking av bjørkemålere i Troms og Finnmark; (iv) Barkbilleovervåkingen 2023: økende fangster – særlig i stormrammede områder; (v) Søk etter Ips-arter utenfor det nordvestlige hjørnet av granas utbredelse i Europa; (vi) Askeskuddsyke; (vii) Andre spesielle skogskader i 2023.
Sammendrag
In 2024, spruce bark beetle (Ips typographus) catches decreased in all counties except Telemark, Sør-Trøndelag, and Nordland. The highest catches this year were observed in Telemark and Buskerud. In Telemark, the catches are the highest recorded since the major spruce bark beetle outbreak that started in the mid-1970s. In Buskerud, while catches have declined compared to last year, they remain historically high. In Oppland, the catches have decreased markedly from the record-breaking year of 2023 but remain at moderately high levels. Across Southern Norway, this year’s catches are slightly above the 46-year average. The relatively high catches in Buskerud and Oppland are likely a delayed response to the storm damage in November 2021, as municipalities heavily affected by the storm report especially high catches. Additionally, field reports in 2024 indicate attacks on standing trees in areas with much windfall after the 2021 storm. Many of these damage reports likely pertain to trees attacked by beetles in 2023 or earlier but that are only now showing visible symptoms. The 2024 bark beetle season was characterized by extremely dry and warm weather in May, followed by a very wet summer with normal to slightly below-average temperatures. The warm May weather coincides with the beetles' primary flight period, favoring beetle dispersal and egg-laying. Additionally, the dry conditions in May may have stressed spruce trees, reducing their resistance to beetle attacks. The wet weather later in the summer likely benefited the trees while being sub-optimal for the beetles. Overall, the weather conditions during the 2024 season were probably relatively favorable for the beetles. A temperature-based development model estimate that, by September 17, the spruce bark beetle could have completed two generations near the Oslofjord, along the southern coastline, and in low-lying inland valleys. However, these model results do not necessarily mean that the beetles completed two generations in 2024 but indicate that conditions were warm enough to make it possible.
Sammendrag
Increasing levels of global environmental change may have negative impacts on fertility and embryo viability in animals that could explain a recently reported increase in hatching failure in bird eggs across the globe. Here we test this relationship again by analyzing a dataset containing almost twice as many species and covering a longer time period than earlier works (n = 431 species during the period 1906–2022). We also tested for effects of Red List status and global population size. We found that hatching failure rates in a combined group of bird species currently classified as threatened (IUCN Red List categories Critically Endangered, Endangered and Vulnerable) or Near Threatened, peaked in the late 1970s to early 1980s and thereafter declined. A similar trend also existed in species with relatively small global populations. In contrast, no temporal trends were found in species in the Least Concern category, or in species with large global populations. Moreover, hatching failure rates declined significantly with increasing global population sizes. The temporal peak of hatching failure rates in threatened and Near Threatened species corresponds with the peak in environmental levels of the insecticide DDT. While this could suggest that environmental pollution caused the temporal trends in hatching failure rates, effects of inbreeding in small and threatened populations sampled more frequently during this period could not be excluded. Although we found no evidence suggesting that the rates of hatching failure in bird eggs are increasing, the current study supports previous works showing that species of high conservation concern appear to be more susceptible to factors leading to reproductive failure than other species.