|| 要旨トップ | 本企画の概要 |
|日本生態学会第60回全国大会 (2013年3月，静岡) 講演要旨
シンポジウム S05-3 (Lecture in Symposium/Workshop)
Pulsed resource subsidies can have pronounced consequences for communities and ecosystem processes through the responses of recipient consumers. Theory has predicted that seasonal timing of the pulsed subsidies can be a critical component that determines the intensity of the cascading effects of the subsidies. However, the most empirical studies of subsidy effects have been done over very short-time scales, and less is known about the importance of subsidy timing in natural systems. We conducted a large-scale field experiment to test if the seasonal timing of the terrestrial invertebrate input into streams affects consumer responses to the subsidy, which can have cascading consequences for whole communities and ecosystem functions. We found cutthroat trout responded strongly to the invertebrate pulse in the early period (June to August), but responded less to the pulse during the late period (August to October). While these consumer responses seemed not to alter the trophic cascade strongly in either period, we found evidence of enhanced nutrient recycling by cutthroat trout in pulsed treatment reaches during the early period. Given the temporal changes in water discharge and temperature, our results suggest the temporal context of physical environment would be important to determining the effects of subsidy timing.