The global climate is undergoing changes in temperature and precipitation that are altering the abundance and distribution of species around the world. Species that are important from conservation, ecological, cultural, and economic perspectives may face decline and extinction in coming decades. Phenology, the timing of biological events, has emerged as a key indicator of species response to global warming and other aspects of climate change. Phenology includes the flowering and leafing out dates of plants, first arrival dates of birds, and other events throughout the year. The ability of scientists to predict how climate change will affect species and biological communities remains very limited, especially at the scale of countries and continents. Researchers in this project will study the year-round phenological trends since 1953 of numerous plant and animal species using data from 176 meteorological sites across Japan and South Korea. These records cover more species, a longer time period, and more sites than any comparable data set from the United States, and can be used to develop innovative methods of analysis that can be applied to species in the United States and elsewhere. At field sites in Japan, the researchers will examine ecological interactions, e.g., between plants and pollinators, to determine the potential for ecological mismatches among species with different responses to climate change. The U.S. researchers will train undergraduate and graduate students and will work with scientists from Japan, South Korea, China, and Europe, and the new U.S. National Phenological Network, thereby strengthening international connections among climate change researchers.
The timing of species’ life history events, such as flowering, insect emergence or leaf color change has important ecological consequences. These phenological events influence individuals’ demographic performance (e.g., growth and survival), competition among individuals (e.g., crops vs weeds), trophic interactions (e.g., crops and insect pests), and ecosystem processes such as plant productivity (determined by the length of the growing season). These ecological consequences have made understanding and quantifying phenological responses to climate an important effort in ecology. However, doing so is complicated by the large geographic, temporal, and taxonomic variation in phenology arising from the complex set of factors that influence phenology. Although thermal forcing (commonly quantified as degree days-accumulation of heat) is understood to be a primary driver of many phenological events, additional weather events such as frosts and precipitation may also have important effects on phenology, but are less often considered. Non-climatic variables, such as photoperiod (day length), competition with neighbors, resource availability, and other site-specific conditions, can further affect phenology and may alter perceived relationships with climate. The relative importance of these different factors will depend on species’ evolutionary histories, but may also vary spatially due to environmental heterogeneity and genetic variability. Forecasting phenological shifts due to climate change requires understanding and quantifying how these multiple factors combine to affect phenology. However, current approaches to analyzing phenological data have a limited ability for quantifying multiple drivers simultaneously. Here, we use a novel statistical approach to estimate the combined effects of multiple variables, including local weather events, on the phenology of several taxa (plants, animals, and fungi). We found that thermal forcing had a significant positive effect on each species, frost events delayed the phenology of the tree and butterfly, and precipitation had a positive effect on fungal fruiting. Using data from sites across latitudinal gradients, we found that these effects are remarkably consistent across sites once latitude and other site effects are accounted for. This consistency suggests an underlying biological response to these variables that is not commonly estimated using data from field observations. This approach’s flexibility will be useful for forecasting ongoing phenological responses to changes in climate variability in addition to seasonal trends. Those forecasts have the potential of being highly valuable across a variaty of disciplines relying on organisms' phenological responses, such us agriculture (crop peak production, pest control, plant-pollinator interactions), conservation (timing of critical events for species of concern), tourism (peak flowering, leaf color change).
