Seasonal variability of soil respiration in multiple ecosystems under the same physical-geographical environmental conditions in central Japan

We investigated the relationships between soil respiration and environmental factors during foliation and defoliation periods in three ecosystems under the same physical-geographical environmental conditions in central Japan. These ecosystems comprised deciduous broad-leaved forest (Quercus crispula dominated, site Q), deciduous needle-leaved forest (Larix kaempferi dominated, site L), and grassland (Zoysia japonica dominated, site Z). Field measurements of soil respiration were made using a closed chamber method with an infrared gas analyzer at monthly intervals in the snow-free seasons from May 2010 to November 2011. Soil respiration began to increase in May, peaked rapidly in summer (July to September), and decreased in November. The seasonal patterns of soil respiration and soil temperature were nearly parallel among the three sites, with one exception, which may have been caused by the decrease in soil water content during summer months (July to September). Although Q(10) values based on the entire measurement period in 2010 were roughly the same as those in 2011 at the three sites, there was a large difference in Q(10) between the foliation and defoliation periods in both years, especially at the two forest sites. These differences among the three sites may be caused by differences in soil temperature dynamics and precipitation activity. To better understand the relationship between soil respiration and environmental factors, continuous observations are needed of soil respiration, environmental factors, and biological activities both below ground and above ground under the same physical-geographical environmental conditions.