Influences of species, latitudes and methodologies on estimates of phenological response to global warming

Abstract

New analyses are presented addressing the global impacts of recent climate change on phenology of plant and animal species. A meta-analysis spanning 203 species was conducted on published datasets from the northern hemisphere. Phenological response was examined with respect to two factors: distribution of species across latitudes and taxonomic affiliation or functional grouping of target species. Amphibians had a significantly stronger shift toward earlier breeding than all other taxonomic/functional groups, advancing more than twice as fast as trees, birds and butterflies. In turn, butterfly emergence or migratory arrival showed three times stronger advancement than the first flowering of herbs, perhaps portending increasing asynchrony in insect-plant interactions. Response was significantly stronger at higher latitudes where warming has been stronger, but latitude explained o4% of the variation. Despite expectation, latitude was not yet an important predictor of climate change impacts on phenology. The only two previously published estimates of the magnitude of global response are quite different: 2.3 and 5.1 days decade À1 advancement. The scientific community has assumed this difference to be real and has attempted to explain it in terms of biologically relevant phenomena: specifically, differences in distribution of data across latitudes, taxa or time periods. Here, these and other possibilities are explored. All analyses indicate that the difference in estimated response is primarily due to differences between the studies in criteria for incorporating data. It is a clear and automatic consequence of the exclusion by one study of data on 'stable' (nonresponsive) species. Once this is accounted for, the two studies support each other, generating similar conclusions despite analyzing substantially nonoverlapping datasets. Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade À1 . This is the first quantitative analysis showing that data-sampling methodologies significantly impact global (synthetic) estimates of magnitude of global warming response.

Geographical pattern in first bloom variability and its relation to temperature sensitivity in the USA and China

“…Therefore, at high latitude, the contribution of stronger warming to advancing trend in spring phenophases can be partly or totally offset by the weaker temperature sensitivity there. This explains why the latitude is not an important predictor of the strength of phenological trends, as suggested by previous studies (Ge et al 2014a;Matsumoto 2010;Parmesan 2007).…”

Terrestrial biosphere models need better representation of vegetation phenology: results from the North American Carbon Program Site Synthesis

“…Analyses of diverse data sets provide compelling evidence for phenological shifts toward earlier spring onset and delayed autumn senescence over the last four decades (Peñ uelas et al, 2002;Badeck et al, 2004;Schwartz et al, 2006;Parmesan, 2007;Parry et al, 2007). These patterns have largely been attributed to climate change, particularly recent warming trends.…”

Reconsidering the Loss of Evolutionary History: How Does Non-random Extinction Prune the Tree-of-Life?

“…With warming, plants might adapt by shifting their phenologies -the timing of life history strategies -for example fl owering earlier and losing leaves later (Parmesan 2007 ). Recent work indicates signifi cant phylogenetic conservatism in fl owering phenology , suggesting that there might be some evolutionary constraints to species adaptive responses.…”