Results presented in Table 7 show that during the last year there were significant seasonal differences. Removals were significantly higher during summer and autumn coinciding with the maximal plant growth. This is supported by results reported by Mandi et al. (1998) and Neralla et al. (1998). These seasonal differences were not observed during the first year (Table 6) because, as it has been already mentioned, the sampling period ranged from June to November.