The mean nutrient score rose, but the mean light score showed no clear change at 1,655 matched Swedish forest plots from 1999–2004 to 2019–2024

We tested changes in mean plant nutrient and light scores at fixed Swedish forest plots over 20 years. We used open National Forest Inventory records and EIVE 1.0 species scores. The main panel had 1,655 plots with full 100 square meter survey areas, productive forest land, visits 20 years apart, dates within 30 days of year, and at least five scored species at each visit. Mean nutrient score rose by 0.0217 on a 0–10 scale (approximate 95% spatial block interval +0.0077 to +0.0358). Mean light score changed by +0.0071 (−0.0219 to +0.0361). An exact partition showed positive recorded gain terms and negative recorded loss terms for both scores. The nutrient terms were +0.0526 and −0.0308; the light terms were +0.0332 and −0.0261. The nutrient change was within species-label shuffle ranges, both without groups and within baseline occupancy groups (two-sided probabilities 0.324 and 0.482). With at least ten scored species, its estimate fell to +0.0090 and the interval included zero. No planned selection check established a light-score decrease. A later check that added four supported synonyms gave similar mean-score results. These are changes in recorded species indices, not direct measurements of soil, canopy, or climate. Detection and recording change remain possible causes. The package has complete compact inputs, source hashes, code, all results, figures, a local plan, and independent checks.

forest vegetation · Sweden · plant indicators · species turnover · repeated surveys · EIVE · nutrient affinity · light affinity