Pål Thorvaldsen

Research Scientist

(+47) 406 21 869
pal.thorvaldsen@nibio.no

Place
Trondheim

Visiting address
Klæbuveien 153, bygg C 1.etasje, 7031 Trondheim

To document

Abstract

The 2025 update of the Norwegian Red List shows that coastal heathlands remain threatened. Key ongoing threats include abandonment of traditional land use and development of the areas. Recently compiled statistics from habitat mapping provide insights into the ecological condition of the heathlands. The data reveal that more than half of the remaining coastal heathland areas lack active management, putting them at risk of encroachment in the coming years. Moreover, data show that the proportion of areas in the late successional phase is surprisingly low, just over ten percent, despite widespread degradation due to encroachment. This suggests that degraded coastal heathlands are difficult to identify and are likely being misclassified as other habitat types, such as forest. To help field surveyors avoid misidentification, a map illustrating the potential distribution of coastal heathlands in Norway has been developed, along with clear inclusion and exclusion principles. The map extends the previously known northern range of heathlands and reaches south eastward toward heathland areas in Sweden. Norway currently lacks representative monitoring of coastal heathland, as existing programs miss rare habitats. It is therefore a welcome step that the Norwegian Environment Agency now proposes the development of a dedicated monitoring program.

To document

Abstract

As droughts become longer and more intense, impacts on terrestrial primary productivity are expected to increase progressively. Yet, some ecosystems appear to acclimate to multiyear drought, with constant or diminishing reductions in productivity as drought duration increases. We quantified the combined effects of drought duration and intensity on aboveground productivity in 74 grasslands and shrublands distributed globally. Ecosystem acclimation with multiyear drought was observed overall, except when droughts were extreme (i.e., ≤1-in-100-year likelihood of occurrence). Productivity losses after four consecutive years of extreme drought increased by ~2.5-fold compared with those of the first year. These results portend a foundational shift in ecosystem behavior if drought duration and intensity increase, from maintenance of reduced functioning over time to progressive and profound losses of productivity when droughts are extreme.