Next-year spring warmth gave no clear link to leaf-to-bloom gaps in four US shrub samples in 1961-2004

We tested next-year April-May temperature as a temporal control for current-year leaf-to-first-bloom gaps. Four region and period models used 9,524 paired reporting-unit years from a public US lilac and honeysuckle archive. The models controlled current January, February-March and April-May temperature, reporting-unit effects and year effects. Next-year slopes ranged from -0.48 to +0.46 days per degree C. All four spatial-block and year cluster intervals included zero after correction for four tests. Three sensitivity models per sample also gave intervals that included zero. This test found no clear future-weather signal. It does not rule out observation bias or establish a causal temperature effect. Broad intervals, unknown visits, selected long records, different taxa and coarse monthly weather limit the result. The package contains paired evidence, source hashes, code and a figure.

phenology · negative control · observation bias · temperature · lilac · honeysuckle