drivers of soil respiration of root and microbial ... - Unitus DSpace

explain diurnal and seasonal changes in root-derived respiration. Laboratory experiments with a
single plant species have shown however that the observed time lag is not stable during the plant
ontogenesis, and vary depending on the plant growing stage. The same photosynthetic activity
could also result in different magnitude of root respiration, depending on the type of nutrient supply
(ex: N in form of NH + 4 or NO - 3). All these finings suggest that root respiration is a complex
process, tightly coupled to plant canopy activity and could not be explained simply by changes in
soil temperature and moisture. Further studies are needed to verify the bonds between aboveground
and belowground processes for different species and vegetation types, as well as for various plant
growing stages.
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Soil temperature and soil water content exerted a significant effect on microbial component
of soil respiration. Being a larger part of total CO2 efflux from soil at Amplero (≈ 70%), these
factors influenced also total soil respiration dynamic on different time scales. Introduction of a
management regime have modified however the activity of microbial community by an increase of
the quantity of easily available C substrates from the rhizodeposition process, resulting in a general
suppression of microbial enzymatic activity and further decrease C mineralization rates.
Combination of laboratory studies and in situ measurements is necessary for understanding of the
effect of changing substrate quality, nutrient and moisture conditions on microbial activity and its C
use efficiency.