Thermal Time, Chill Days and Prediction of Budburst in Picea sitchensis

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 132.174.254.159 on Wed, SUMMARY(1) The dates of budhurst of lateral shoots on 2to 10-year old trees of Picea sitchensis were recorded on fourteen occasions at sites near meteorological stations in lowland and upland Britain between 1960 and 1980.(2) The following relationship accounted for 92% of the variation in thermal time from 1 February to the date of budburst among the fourteen observations: thermal time = 67.4 + 4401.8 exp (-0.042 x chill days)where thermal time was day degrees > 5 IC accumulated from 1 February, and chill days were the number of days <5 "C counted from 1 November, both based on mean daily air temperature ((max. + min.)/2). This model may be used to estimate the date of budburst on young P. sitchensis of most provenances growing in upland Britain.(3) The following features or assumptions of the model were examined with reference to the literature and/or by experimentation: the small effect of provenance; linearity in the relationship between bud growth rate and temperature; the large effect of chilling on thermal time to budhurst; the omission of daylength and soil temperature as variables; the choice of starting dates for effective chilling and thermal time; and the use of simple fixed base temperatures.(4) The model was applied to mean daily temperatures at Eskdalemuir for the period 1912-82. The predicted dates of budburst ranged from 23

Climatic determinants of budburst seasonality in four temperate‐zone tree species

“…The Spring-Warming model (Cannell & Smith, 1983), SeqSar and Par1Sar models (Chuine et al, 1999) were used in the present analysis because they have been shown to be the most effective models among the different ones proposed in the literature. The Spring-Warming model assumes that budburst occurs when a critical sum of degree-days (more generally named forcing units, F *) above a certain threshold (Tb), cumulated from a fixed date (t " ) is attained ( Table 1).…”

Assessment of Biological and Environmental Phenology at a Landscape Level from 30 Years of Fixed-Date Repeat Photography in Northern Sweden

“…For each site, three trees were monitored weekly and scored according to Tenow et al (2001) phenophases for birch buds/leaf development. However, because Tenow et al (2001) phenophases could not be accurately judged from the landscape scale photographs; six clearly identifiable phenophases were assigned (see Supplementary Table), and matched to those described by Tenow. Thermal requirement for full foliage cover was calculated according to Cannell and Smith (1983) for each year. Base temperatures of 0, 0.5, 1, 1.5 and 2°C were considered; with accumulations beginning 1st March (no instances of positive temperatures occurred prior to this date).…”

Estimating sowing and harvest dates based on the Asian summer monsoon

“…The effective temperature is a function of air or leaf temperature and differs between models. The integrated effective temperature in each development stage is referred to as the thermal time of that development stage (Cannell and Smith, 1983;McMaster and Wilhelm, 1997); there may also be an additional photoperiod length dependence. The thermal time in each development stage is typically set by the user and can be calibrated to simulate different varietal properties.…”