Climate impacts
Boreal canopy lichens declined from several drivers
Open access · cc by · source: Europe PMC
Over a decade of Swedish forest inventory, hair lichens Alectoria, Usnea, and Bryoria became less common, with losses tied to forestry, nitrogen, and climate together—not one driver alone.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
NICHD Scandinavian SGA-study pairs found 55 of 412 children (12%) overweight or obese at age 5. Increasing maternal PFAS associated with higher BMI and triceps z-scores and with overweight, but associations differed by country and concentration; organochlorines were less consistent. Swedish NFI lichen occurrence, modeled 10 years apart, fell for three genera (Alectoria relative loss ~1.70%/year; more than half of Alectoria records lost in region 3) — presence/absence change, not human disease odds.
Evidence for the claim as stated.
Study at a glance
- Design
- Cohort — Repeat Swedish National Forest Inventory plots relating canopy-lichen change to forestry, N deposition, and climate
- N
- NFI plots measured ~10 years apart (1993–2002 vs 2003–2012) with at least one live Picea ≥150 mm DBH
- Population
- Filamentous lichens on spruce in productive Swedish boreal forest
- Outcome
- Large-scale canopy-lichen decline has multiple interacting drivers: logging cycles, nitrogen sensitivity, and warming/rain
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Boreal canopy lichens declined from several drivers
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Relative loss rates were 1.70%, 1.25%, and 0.50% per year for the three lichens.
This corresponds to 1.70%, 1.25% and 0.50% relative loss rates per year, assuming constant loss rates over the 10‐year period.
51.6% of Alectoria occurrences were lost in region 3.
More than half of the Alectoria occurrences (51.6%) was lost in region 3 (Figure ), followed by substantial decreases of Usnea in regions 3 (20.2%) and 4 (30.1%), whereas Bryoria decreased in regions 1 (13.6%) and 2 (6.3%).
Key findings
National occurrence fell for all three genera (Alectoria relative loss ~1.70%/year). More than half of Alectoria records were lost in region 3. Drivers interacted: logging cycles, N sensitivity, and warming/rain all mattered, and traits such as color and dispersal shaped which genus declined where.
Methodology
Authors used Swedish NFI plots measured 10 years apart (1993–2002 vs 2003–2012) to track occurrence and thallus length of three filamentous canopy lichens on spruce, then related changes to forestry, N deposition, and climate variables.
Limitations
NFI presence on host trees does not measure biomass in the upper canopy or prove which single driver would reverse the trend if managed alone.
Related papers in this topic
Same topic cluster — not a recommendation engine.