Franca Sangiorgio

Inter- and intra-habitat variability of plant detritus decomposition in a transitional environment (Lake Alimini, Adriatic Sea)

A comparative analysis of inter- and intra-habitat variations of detritus decay rates across ecosystem types was carried out in the Lake Alimini complex (Italy) to assess the relevance of major structural ecosystem features on detritus processing rates. Reed (Phragmites australis) detritus decomposition was studied in a stream, a freshwater lake and a salt marsh on a seasonal basis at a total of 20 sampling stations using the leaf pack technique. Overall, the spatial variability of leaf decomposition rates was more pronounced than the temporal variability, decomposition rates in the stream being 3.6 and 5.2 times faster than in the freshwater lake and salt marsh, respectively. The intra-habitat spatial variability of leaf decay rates in the stream was also higher than in the other systems. Environmental features were relevant factors affecting intra- and inter-habitat variation of reed decay rates, and their relevance to leaf detritus decomposition showed a strong seasonal variation.

Influence of Drought and Abiotic Factors on Phragmites australis Leaf Decomposition in the River Pula, Sardinia, Italy

ABSTRACT Temporal and spatial patterns of Phragmites australis leaf decomposition and the relative influence of summer droughts and abiotic features were studied in a Mediterranean-type river basin, the River Pula. Reed processing rates varied among seasons and sites, being on average significantly faster in the cold seasons (i.e., winter-spring) than in the warm seasons (i. e., summer-fall) and in low rather than in high stream order reaches. On the other hand, at sites protected from summer drought events (i.e., wet sites), decay rates were faster in the warm than in the cold season. Along stream order, leaf decay rates were significantly faster at wet sites than at sites suffering from summer droughts. Summer drought events explained 44% of reed decay rate spatial variability, and major water abiotic parameters explained an additional 8%.