Herbarium records are reliable sources of phenological change driven by climate and provide novel insights into species' phenological cueing mechanisms

Abstract

Our findings support the use of herbarium records for understanding plant phenological responses to changes in temperature, and also importantly establish a new use of herbarium collections: inferring primary phenological cueing mechanisms of individual species (e.g., temperature, winter chilling, photoperiod). These latter data are lacking from most investigations of phenological change, but are vital for understanding differential responses of individual species to ongoing climate change.

Shifts in frog size and phenology: Testing predictions of climate change on a widespread anuran using data from prior to rapid climate warming

“…Because wood frogs have explosive breeding events, with reports showing up to 80% of breeding occurring within 3 days, for example (Petranka & Thomas, 1995; Waldman, 1982), and because they are typically collected during the breeding season, we considered Julian day of collection to be synonymous with breeding events. Although we know of no study which has previously used collection date as a proxy for breeding date in frogs, collection date has been used to measure change in phenology for other taxa (Davis, Willis, Connolly, Kelly, & Ellison, 2015; Scharlemann, 2001). Additionally, given that male and female wood frogs arrive at breeding sites within a few days of each other (Howard, 1980; Waldman, 1982), we believe collection date combined with natural history knowledge can be used as a proxy for breeding in this species.…”

Studying plant–pollinator interactions in a changing climate: A review of approaches

“…To determine whether herbarium specimens are a valid approach for assessing change in flowering phenology in response to climate, two formal analyses have compared herbarium specimens to long-term field observations (Robbirt et al, 2011; Davis et al, 2015). Comparison of temperature (3-mo mean) and peak flowering time using herbarium specimens (1848–1958) of an orchid revealed the same relationship (slope) with mean temperatures as recorded observations of peak flowering from 1975–2006 in one site (Robbirt et al, 2011).…”

“…Comparison of temperature (3-mo mean) and peak flowering time using herbarium specimens (1848–1958) of an orchid revealed the same relationship (slope) with mean temperatures as recorded observations of peak flowering from 1975–2006 in one site (Robbirt et al, 2011). Comparing these approaches for plant communities, Davis et al (2015) compared estimates of flowering onset from herbarium specimens (late 1800s to mid-1900s) with several field observation data sets of flowering onset (1852–2013) for 20 species near Concord, Massachusetts, USA. Analyses of the slope of individual species from a regression of temperature and flowering onset from specimens or field observations (as the response variable) did not reveal any significant differences.…”

Calling attention to the new Brown University Herbarium

“…A more recent review of the use of herbarium specimens (Lavoie, 2013) documented their use in studies focused on biogeographical patterns, collection biases, plant diseases, and climate change-induced impacts on plant distribution. Herbarium specimens have also been part of studies investigating changes to atmospheric ozone concentrations (Ryan et al, 2009) and are critical components of studies examining changing patterns of chronological events (Primack et al, 2004;Calinger et al, 2013;Everill et al, 2014;Hart et al, 2014;Park and Schwartz, 2015;Davis et al, 2015). All these studies indicate a growing interest in using herbarium collections for environmental and ecological research.…”