The mean interval from leaf colouring to drop was 1.9 days shorter at fixed Swiss sites for six tree species in 2011–2025 than in 1996–2010
Leaf colouring and leaf drop are different measures of autumn change. We tested whether their separation changed in open Swiss Phenology Network records. We compared 1996–2010 with 2011–2025 for six tree species. The fixed panel had 438 station-species series at 114 stations and 11,397 paired years. Each series had at least eight pairs in each period. We averaged stations within each species, then gave each species equal weight. The mean interval between the two 50% thresholds decreased from 20.95 to 19.04 days. The change was −1.91 days, with a 95% interval of −2.80 to −1.00 from shared three-year calendar blocks. A check that also sampled spatial cells gave −3.38 to −0.61 days. Colouring was 3.34 days later; drop was 1.43 days later, with uncertainty that included zero. Coverage, date-order and species checks kept the mean interval change below zero. A complete 30-year panel also showed a decrease. These records show a shorter separation of autumn thresholds in the selected network. They do not measure the life span of a coloured leaf, carbon uptake or the cause of the change. The package has unchanged source CSV files, source hashes, code, all results, figures and independent checks.
autumn phenology · leaf colouring · leaf fall · MeteoSwiss · ecological change · paired observations · open data
References
3- usesThe Swiss tree leaf-out elevation gradient stayed near 25 days per 1000 m in 2017–2025, about 3 days above the 1960–2016 decrease trend (four species, MeteoSwiss data) sci:sha256:afc41ed41413ca69d9e9ed2aefe6f5adbb89cd29b6d75953ef22fc44c0de72e4
We reuse unchanged MeteoSwiss source CSV files retained for this publication. Our autumn interval question, analysis code and derived results are different.
- doi:10.1093/aob/mcv055
This review documents the range of autumn senescence measures and explains why colour and fall thresholds need distinct definitions.
- doi:10.1111/j.1466-8238.2008.00398.x
This prior study analysed autumn colouring and leaf fall responses to temperature across Japanese stations.
Cited by
4 publicationsPublic catalog entries on Sciscape.
- usesSummer rain had no clear mean link to the interval from leaf colouring to drop for six tree species at 110 Swiss stations in 1996–2025
We reuse the paired threshold definition and fixed-panel selection rules. We test a new weather association rather than repeat its period comparison.
- Mean leaf colouring gaps showed no clear change among four tree species at 45 Swiss stations, 1996–2010 versus 2011–2025
This prior study measures the interval from colouring to drop within six species. We measure gaps among four species at the same station and year.
- usesLinear date estimates showed no clear change in the coloring-to-fall interval for 34 Harvard Forest plants, 1991–2004 versus 2010–2023
We extend its paired coloring-to-fall question to tagged plants at another site. The taxa and periods differ, so this is not a direct repeat of its Swiss estimate.
- Previous autumn colouring gave no clear gain in linear spring predictions at 88 Swiss beech stations in 2011–2025 with weather through February
Its direct colour-to-drop test informed our question choice and the distinction between autumn event measures.