Hopp til hovedinnholdet

Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2025

To document

Abstract

In 2024, our sample remained stable with 27 participating countries and the largest number of assessed plots since 2019. We witnessed a very slight increase of 0.2 percentage points (%p) in mean defoliation as compared to 2023, mainly due to an increase of 0.5%p for broadleaves, while defoliation of conifers remained almost unchanged (0.1%p decrease). The strongest increase in defoliation occurred in deciduous (sub-) Mediterranean oaks (+2.1%p), while the strongest decrease was recorded in Norway spruce (-0.8%p). Deciduous temperate oaks had the highest (29.7%) and Norway spruce the lowest (22.4%) mean defoliation. Trend analyses show a considerable increase in defoliation of evergreen oaks (7.1%p), common beech (6%p), Norway spruce (5.5%p), and deciduous temperate oaks (5%p) over the past 20 years. The increase in defoliation for Scots pine and Mediterranean lowland pines (3.7 and 3.3%p, respectively) was more moderate. The results of the trend analyses were not significant for deciduous (sub-) Mediterranean oaks and Austrian pine. The percentage of trees with damage symptoms (48.6%) was almost the same as in 2023 (-0.5%p). As in previous years, the number of damage symptoms per assessed tree was substantially higher for broadleaves than for conifers (0.86 vs. 0.55, respectively). Insects, abiotic causes, and fungi were the most common damage agent groups for all species, comprising altogether more than half of all damage records. Tree mortality in 2024 was 1.1% (1 145 trees), i.e. at the same level as in the year before. While mortality rates for the main species and species groups ranged from 0.6 to 1.6%, mortality of Betula spp. and European ash was higher with 2.4% and 7% respectively.

To document

Abstract

Aim Species coexistence is based on resource partitioning and modulates biodiversity patterns across climates, latitudes and altitudes. Resource partitioning can occur via niche size or separation in the geographic range or ecological niche. While resource partitioning promotes biodiversity, the impact of different partitioning strategies on species richness remains largely unexplored. Location Two ecosystems with similar climates and ages are the species‐rich tropical alpine ecosystem in the South American Andes and the more species‐poor tropical alpine ecosystem in the eastern African mountains. Time Period Present‐day distribution and climatic conditions, integrating phylogenetic information extending back to the last 7 million years maximum. Major Taxa Studied Six lineages from the Asterales; three in each ecosystem, respectively. Methods We test whether geographic range and climatic niche partitioning strategies may explain differences in species richness between two ecosystems. We combine phylogenomic data with occurrence records and estimate metrics of size and overlap for climatic niche and geographic range. Results We show that the Andean species have larger climatic niches than the African species, suggesting that niche size is not explaining higher species richness in the Andes. Instead, a striking pattern for species with overlapping geographic ranges emerged: the Andean species show less climatic niche overlap than the African species, indicating more effective niche separation among Andean species. Main Conclusions We hypothesise that differences in resource partitioning, specifically increased niche separation among geographically overlapping species in the Andes compared to the eastern African mountains, contribute to the species richness difference between these tropical alpine biodiversity hotspots.