Dinamica spazio-temporale della respirazione eterotrofa del suolo in un sistema agrario mediterraneo

This study focuses on the relationship between land use and soil heterotrophic respiration (Rh) in a Mediterranean agroecosystem under different long term managements: tilled vineyard, grass covered vineyard, rotation of haycrop-pasture with scattered trees of cork oak. Within management we distinguished between microenvironments under or out tree soil canopy influence. Autotrophic respiration was excluded by trenching method. Rh, soil temperature (T) and soil water content (SWC) were measured at the same time, within an year with a frequency between once a week and once a month depending on weather variability, from 9:00 to 14:00 (solar time). Rh was measured with a portable and closed chamber connected to an IRGA. There was a strong seasonal variation in Rh with maximums in spring and autumn. Rh values were averaging higher in haycrop and pasture and lower in the tilled vineyard than in the grass covered vineyard. Moreover, in the pasture and haycrop, the dynamics were affected by positions with respect to woody plant canopy soil vertical projections. In fact, in spring, higher values were observed out tree canopy than under, while in autumn the opposite trend was observed. Rh seasonal variation was correlated to SWC and soil T, except at the maximums. Spatial variation in Rh was found to be correlated to soil organic matter content.