Phenological traits of vegetation: examples of some phytocoenoses from selected vegetation series

The symphenological analysis of phytocoenoses allows us to assess the individual and collective rhythms of the growth, flowering and fruiting of plant communities. In the temperate zone, it can be assumed that the phenological timing is optimally adapted to the seasonal period favourable for growth and reproduction and that the natural selection acts by means of synchronising (temperature, rain, frost and drought risks) and asynchronizing factors (competition for resources, pollinators and seed dispersal). Species can be categorized into phenological types selected a priori or by agglomerative methods (clustering) (Puppi et al.1994, Fitosociologia 26). The symphenological pattern of a plant community is usually represented graphically by symphenograms, while the synchrony or the asynchrony (diversity) can be evaluated by numerical methods. Moreover, the analysis of phenological traits of a phytocoenosis can be compared and related with other features and criteria of classification (Taxonomy, Syntaxonomy, Chorology, pollination types, ecological and morpho-physiological traits ) in order to assess the relationship between seasonal timing and the other attributes of plants. Each phytocoenosis has a typical symphenological pattern, that is subject to variations (anomalies) depending on the weather and also on the stress and disturbance level. In Europe, climatic change has already caused a significant shift in phenophases timing: an advance of spring phases and an extension of the growing season. Moreover, species have been found to respond differently to climate change (Menzel et al. 2006, Global Change Biol. 12): pheno-anomalies can lead to variations in the fitness of some species and consequently the competitive relationships within a plant community will alter, possibly until the loss of biodiversity. In order to predict the consequences of climatic impact on plants it is important to assess the phenological fingerprints (Root et al. 2003, Nature 421) of the most sensitive phytocoenoses (an example on summit vegetation is given) and to construct pheno-climatic models suitable for forecasting future scenarios. Besides the climate, the disturbance too can produce \u201cpheno-anomalies\u201d (examples: the effect of mowing a grassland and of defoliation by grubs in a wood). Thus, the analysis of phenological traits of vegetation is a useful tool in characterizing ecological features of phytocoenoses and in predicting the plant responses to the natural and anthropic impact. In fact, a global view of plant communities both in descriptive and functional terms, increases their bio-indication value and their benefit in the applications for the sustainable management of ecosystems