Abstract
Accumulated growing degree-days (aGDD) are widely used to predict phenological stages of plants and insects. It has been shown in the past that the best predictive performance is obtained when aGDD are computed from hourly temperature data. As the latter are not always available, models of diurnal temperature changes are often employed to retrieve the required information from data of daily minimum and maximum temperatures. In this study, we examine the performance of a well-known model of hourly temperature variations in the context of a spatial assessment of aGDD. Specifically, we examine whether a generic calibration of such a temperature model is sufficient to infer in a reliable way spatial patterns of key phenological stages across the complex territory of Switzerland. Temperature data of a relatively small number of meteorological stations is used to obtain a generic model parameterization, which is first compared with site-specific calibrations. We show that, at the local scale, the predictive skill of the generic model does not significantly differ from that of the site-specific models. We then show that for aGDD up to 800 °C d (on a base temperature of 10 °C), phenological dates predicted with aGDD obtained from estimated hourly temperature data are within ± 3 days of dates estimated on the basis of observed hourly temperatures. This suggests the generic calibration of hourly temperature models is indeed a valid approach for pre-processing temperature data in regional studies of insect and plant phenology.
Highlights
Air temperature is the main determinant of plant and insect growth (Huey and Stevenson 1979; Deutsch et al 2008), a well-known fact that led to the development of conceptual models relating plant and insect phenology to temperature already in the middle of the eighteenth century (Allen 1976; Wilson and Barnett 1983)
Important in this context is the total amount of heat required for an organism to develop from one point to another in its life cycle (Baskerville and Emin 1969). This is usually expressed in terms of accumulated growing degree-days, that is to say, the integral over a given period of time of the daily excess of temperature over a lower developmental threshold, the so-called base temperature (Baskerville and Emin 1969; Prentice et al 1992)
We adopted the model of Parton and Logan (1981) but with improvements concerning (i) the phase shift of the sinusoid invoked to simulate day-time temperature variations, (ii) the exponential decay at night, and (iii) the specification of temperature at sunset and minimum temperature to model the exponential decay in the early morning hours and the late evening hours
Summary
Air temperature is the main determinant of plant and insect growth (Huey and Stevenson 1979; Deutsch et al 2008), a well-known fact that led to the development of conceptual models relating plant and insect phenology to temperature (as a measure of heat availability) already in the middle of the eighteenth century (Allen 1976; Wilson and Barnett 1983) Important in this context is the total amount of heat required for an organism to develop from one point to another in its life cycle (Baskerville and Emin 1969). The approach has been adopted for climate change impact
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
