Current and lagged climate affects phenology across diverse taxonomic groups

Abstract

The timing of life events (phenology) can be influenced by climate. Studies from around the world tell us that climate cues and species' responses can vary greatly. If variation in climate effects on phenology is strong within a single ecosystem, climate change could lead to ecological disruption, but detailed data from diverse taxa within a single ecosystem are rare. We collated first sighting and median activity within a high-elevation environment for plants, insects, birds, mammals and an amphibian across 45 years (1975-2020). We related 10 812 phenological events to climate data to determine the relative importance of climate effects on species' phenologies. We demonstrate significant variation in climate-phenology linkage across taxa in a single ecosystem. Both current and prior climate predicted changes in phenology. Taxa responded to some cues similarly, such as snowmelt date and spring temperatures; other cues affected phenology differently. For example, prior summer precipitation had no effect on most plants, delayed first activity of some insects, but advanced activity of the amphibian, some mammals, and birds. Comparing phenological responses of taxa at a single location, we find that important cues often differ among taxa, suggesting that changes to climate may disrupt synchrony of timing among taxa.

Keywords: climate change; lags; long-term; montane; phenological mismatch; phenology.

Figure 1.

Potential phenological responses to climate. Colours represent the season in which a cue or response occurs: green = spring, yellow = summer, red = fall and blue = winter. (a) Both within and across species, one cue might lead to multiple responses, or several cues might lead to a single response. Examples of one cue influencing several responses are A1) temperature cueing both flower and fruiting timing within the same species or A2) snowmelt date cueing first day of activity of small mammals and insects. Examples of several cues leading to a single response are A3) temperature and precipitation jointly initiating bird song or A4) first activity of insects responding to temperature while first activity of salamanders responds to precipitation. For a particular cue such as precipitation, species may respond to (b) different aspects of the cue e.g. mean, minimum, maximum, variance or growing season total or (c) the season in which the cue occurs, such as winter temperature cueing tree flowering whereas spring temperature cues butterfly activity.

Figure 2.

Estimated regression coefficients (β) from best-fit multiple linear regressions of environmental correlates on (a) first and (b) median emergence or sighting dates of plant, insect, mammal, amphibian and bird species at the RMBL. Each point represents a separate species or life stage. Parentheses next to taxa show the number of species used. Information on first and median phenology were available for different insect species (see Methods); we denote the groups with A and B. Subscripts next to covariates indicate either the year of sampling (t), or the year prior to sampling (t − 1) as a test for lagged effects of climate on phenology metrics. See electronic supplementary material, figure S2 for lagged timeframes and Methods for calculation of cold severity index. Different letters next to boxplots represent significant differences in pairwise comparisons across taxonomic groups (p < 0.05). Absence of letters next to boxplots for a climate cue indicates lack of significantly different responses across taxonomic groups. Points to the left of zero indicate advances in phenology and those to the right indicate delays. Colours denote the season of a given weather variable: green = spring, yellow = summer, red = fall and blue = winter.

Figure 3.

Principal components analysis ordination of (a) first and (b) median emergence or sighting dates of plant, insect, mammal, amphibian and bird species at the RMBL. Each point represents estimated regression coefficients for a species or life stage. Vectors indicate the direction and magnitude of correlations of climatic cues determining phenology (electronic supplementary material, table S13). Ellipses are the 95% confidence interval surrounding the centroid for each taxon's phenology. Too few points were available to calculate 95% ellipses for amphibian first activity or mammal first and median activity.