Experiments Are Necessary in Process-Based Tree Phenology Modelling

• Published in: Trends in plant science Vol. 24; no. 3; pp. 199 - 209
• Main Authors: Hänninen, Heikki, Kramer, Koen, Tanino, Karen, Zhang, Rui, Wu, Jiasheng, Fu, Yongshuo H.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2019; Elsevier BV
• Subjects: Air temperature; bud burst; Climate Change; Climate effects; Climate models; Computer simulation; dormancy; Environmental assessment; Environmental factors; Experimental research; Mathematical models; Models, Theoretical; Phenology; Physiology; process-based modelling; Seasons; Spring (season); Temperature; Trees; process-based modelling; bud burst; dormancy; phenology; climate change
• ISSN: 1360-1385; 1878-4372
• DOI: 10.1016/j.tplants.2018.11.006

In boreal and temperate trees, air temperature is a major environmental factor regulating the timing of spring phenological events, such as vegetative bud burst, through underlying physiological processes. This has been established by experimental research, and mathematical process-based tree phenology models have been developed based on the results. The models have often been applied when assessing the effects of climate change. Currently, there is an increasing trend to develop process-based tree phenology models using only observational phenological records from natural conditions. We point out that this method runs a high risk of producing models that do not simulate the real physiological processes in the trees and discuss experimental designs facilitating the development of biologically realistic process-based models for tree spring phenology. Studies addressing spring phenology of trees are increasingly topical because of the ongoing climate change. Spring phenology of trees is often studied with process-based mathematical models, which simulate physiological processes underlying the timing of phenological events, such as vegetative bud burst. Process-based tree phenology models are often used in computer simulations for projecting the effects of future climate warming on trees and forest ecosystems. Traditionally models have been developed with the aid of growth chamber and greenhouse experiments, which have facilitated the determination of environmental responses of the physiological processes. However, nowadays models are often developed without experimental research, using observational long-term phenological records, or remote-sensed data, gathered in natural conditions as the only biological information.