A widely used approach for inferring species’ phenological responses to climate change is to obtain long-term phenological data. However, observational data on leaf-out times are limited and until now based on a small sample of species. To obtain longer time series, I am using herbarium specimens, which for suitable species yield data as far back as 140 years. The “herbarium method” opens up the possibility to study species’ phenological behavior in their native ranges and within-species phenological variations along latitudinal gradients, at least for species frequently collected.
Zohner C.M., Renner S.S. 2014. Common garden comparison of the leaf-out phenology of woody species from different native climates, combined with herbarium records, forecasts long-term change. Ecology Letters 17, 1016–1025.