Abstract
Phenological responses to changing temperatures are known as “fingerprints of climate change,” yet these reactions are highly species specific. To assess whether different plant characteristics are related to these species‐specific responses in flowering phenology, we observed the first flowering day (FFD) of ten herbaceous species along two elevational gradients, representing temperature gradients. On the same populations, we measured traits being associated with (1) plant performance (specific leaf area), (2) leaf biochemistry (leaf C, N, P, K, and Mg content), and (3) water‐use efficiency (stomatal pore area index and stable carbon isotopes concentration). We found that as elevation increased, FFD was delayed for all species with a highly species‐specific rate. Populations at higher elevations needed less temperature accumulation to start flowering than populations of the same species at lower elevations. Surprisingly, traits explained a higher proportion of variance in the phenological data than elevation. Earlier flowering was associated with higher water‐use efficiency, higher leaf C, and lower leaf P content. In addition to that, the intensity of shifts in FFD was related to leaf N and K. These results propose that traits have a high potential in explaining phenological variations, which even surpassed the effect of temperature changes in our study. Therefore, they have a high potential to be included in future analyses studying the effects of climate change and will help to improve predictions of vegetation changes.
Highlights
Changes in phenology are observable indicators for climate change, as especially spring phenology is susceptible to warming temperatures (Menzel & Fabian, 1999; Parmesan & Yohe, 2003; Root et al, 2003)
We investigate whether the species-specific differences in the intensity of observed shifts in first flowering day (FFD) along elevational gradient can be explained with functional traits
To test whether we find similar patterns for growing degree days to start FFD (GDDFFD), the same models analyzing the difference GDDFFD in along the elevational gradient between species, gradients, and year of observation were set up using GDDFFD as dependent variable instead of FFD
Summary
Changes in phenology are observable indicators for climate change, as especially spring phenology is susceptible to warming temperatures (Menzel & Fabian, 1999; Parmesan & Yohe, 2003; Root et al, 2003). Most studies have focussed on relating phenological shifts to temperature changes, but a few have explored the variation in species response with respect to their functional traits (e.g., Fitter & Fitter, 2002; König et al, 2018; Sun & Frelich, 2011). We investigate whether the species-specific differences in the intensity of observed shifts in FFD along elevational gradient can be explained with functional traits. We used elevational gradients to investigate the association between changes in flowering phenology in response to changing environments (i.e., air temperature) and plant functional traits. Studying the phenology of herbaceous plants complements our knowledge on vegetation responses to environmental changes, and the output of this study may serve as a first step to understand the role of trait values for variations in flowering phenology and to improve predictions of vegetation changes
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