Population characteristics of giant reed (Arundo donax L.) in cultivated and naturalized habitats

• Density, morphology and biomass were significantly varied among habitats.
• Cultivated population had the maximum values for most measured parameters.
• Height, branches number and panicle length were positively correlated with density.
• Increased salinity was associated with decrease in shoot height and biomass.
• Simple equations were developed for predicting the shoot biomass of A. donax.

In the present study, we analyzed the variability among naturalized and cultivated giant reed (Arundo donax L.) populations in terms of density, morphology and primary production along the prevailing environmental gradient in Nile Delta, Egypt. For this purpose, a sampling was carried out in homogeneous and monospecific A. donax stands in Nile Delta. The samples were collected to represent the cultivated populations (planted habitat) and the naturalized populations in four habitats (canal banks, waste lands, road and railway sides). Each habitat was represented by 3 stands; and in each stand, density, morphology and biomass were recorded using five randomly distributed quadrats (each of 0.5 × 0.5 m). The results had indicated a significant variation in density, morphological and biomass parameters between naturalized and cultivated populations. Generally, naturalized populations along the railway and road sides (the less moist habitats) had the minimum values for most measured population parameters, while the cultivated populations (the moistest habitat) had the maximum. The dependence of shoot height, number of branches and panicle length on shoot density indicated the density-size effects. Density, morphology and biomass of A. donax were correlated significantly with some soil properties such as salinity, pH, organic matter and nitrogen. The regression technique was applied to develop equations for predicting the biomass of A. donax shoots from more easily determined shoot height and shoot basal diameter. These methods were time-saving, so the equations might be useful in evaluating management techniques which were used for monitoring A. donax.