Heterogeneous intra-annual climatic changes drive different phenological responses at two trophic levels

Abstract

A shift in a life cycle event of one species relative to other species in an ecosystem should be considered more relevant than an absolute shift in phenological dates. However, there is very little evidence regarding the differential effects of climate change on the phenologies of different trophic levels and their potential effects on ecosystem functioning. The Japan Meteorological Agency has monitored the flowering of 4 Prunus tree species and the appearance date of the butterfly Pieris rapae (a proxy for potential pollinators) in spring at Nagano, Japan, since 1953. Flowering tended to occur earlier over the last 3 decades, whereas the appearance of the butterfly was delayed. The effects of climate and the timing of the sensitive period differ between both trophic levels. The plants were strongly affected by temperature (r = -0.87) 30 to 40 d prior to flowering, whereas the butterfly was less affected by temperature (r = -0.50), and the effects mainly occurred during the 15 d prior to its appearance. The temperature during the plants' sensitive period has increased sharply since 1953, whereas the temperature during the butterfly's sensitive period has not changed significantly. The phenologies of the plants and butterfly are changing in opposite directions because they use different climatic cues with different temporal trends. This is the first documentation of differential effects of climate change between plant and insect phenology in Japan. © Inter-Research 2008.