Phenological shifts in plant species are one of the most conspicuous signs of climate change impact on the biosphere. Modeling phenological variations of plant species over broad regions is challenging because of the varied climatic requirements of geographic populations due to local adaptation. In this study, we developed an empirical method to calibrate phenological models of temperate trees using latitude as a predictor to account for local adaptation of populations to a N–S temperature gradient. Fourteen widely distributed tree species in the eastern U.S.A. were investigated using data from the USA-National Phenology Network. We implemented the method in a basic thermal time bud break model to introduce the algorithm of the method and test its effectiveness. For each species, dates of breaking leaf buds were first predicted using a traditional non-spatial model and then with a spatial model that has the critical thermal forcing requirements calibrated for different populations at varied latitudes. As anticipated, non-spatial model predictions that assumed a uniform forcing requirement across latitudes showed consistent and systematic biases at both higher (overestimation-predictions being later) and lower (underestimation-predictions being earlier) latitudes. Spatial models that have been calibrated using our method removed the geographic biases and yielded latitudinal gradients that more closely matched those of the observations. The spatial models also reduced the overall prediction errors from an average root mean square error (RMSE) of 32.2 days to 20.4 days for the training dataset and an average root mean square error for prediction (RMSEP) of 32.2 days to 19.9 days for the testing dataset. This paper is focused on introducing the new calibration method as a preparatory step toward developing operational models that may potentially predict large-scale and range-wide phenological responses of various plant species to climatic changes with improved local accuracy.
|Number of pages||14|
|Journal||International Journal of Biometeorology|
|State||Published - Nov 2021|
Bibliographical noteFunding Information:
We would like to thank Dr. Heikki Hänninen for providing insightful feedback on this research. Phenological data used in this study were provided by the USA National Phenology Network and the many participants who contribute to its Nature’s Notebook program. The study was partly supported by a USDA-NIFA hatch fund SD00H694-20 to JW. We also thank the two anonymous reviewers for their helpful comments.
© 2021, ISB.
- Climate adaptation
- Nature’s Notebook
- climate change
- phenological forecasting
- spring phenology
ASJC Scopus subject areas
- Atmospheric Science
- Health, Toxicology and Mutagenesis