Ecological indicators applied to urban and suburban floras

Among the many approaches to ecological indicators, ecological indicators derived from the floristic composition of a site (i.e. Raunkiaer’s forms spectrum or the percentage of different geographical distribution types-chorotypes) are well established in botanical and ecological literature. Nonetheless their relationship with other indicators, such as Ellenberg’s ecological indicators, or the Grime model [Grime, J.P., 2002. Plant Strategies, Vegetation Processes and Ecosystem Properties. Wiley, Chichester] and the Hemeroby index [Kowarik, I., 1990. Some responses of flora and vegetation to urbanization in Central Europe. In: Sukopp, H., Hejny, S., Kowarik, I. (Eds.), Urban Ecology. Plants and plant communities in urban environments. SPB Academic Publishing, The Hague] is still poorly explored. We concentrated on an urban ecosystem because such areas, due to heir high degree of artificialization, are particularly well suited for studying the interaction of anthropical disturbance with other processes of the ecosystems. This paper attempts to select a small indicator frameset of many already proposed indicators which best express the variability of the sites studied. A floristic-ecological investigation has been carried out in 10 urban sites, of which 6 were archeological, located in the centre of Rome and 4 suburban, semi-natural, in the NE of the town. Ecological indicators have been calculated on this data set. The Pearson correlation test was then applied to verify whether the indicators were independent, while stepwise regression analysis was done to evaluate the statistical weight of each ecoindicator. Disturbance and temperature are the main factors shaping the composition of the sites studied. They are largely interacting and are well expressed with the help of a small subset of the initial set of 19 indicators, namely, by indicators related to life forms and to the geographical distribution of species: Therophytes/Hemicryptophytes, Mediterranean/large distribution, Eurasiatic/large distribution, Mediterranean/Eurasiatic species. The information provided by Ellenberg’s indicators values and Grime’s life strategies are largely summarized by these chorological indicators

Reliability and effectiveness of Ellenberg’s indices in checking flora and vegetation changes induced by climatic variations

Two methods are proposed to assess the significance of time-spanned local variations of Ellenberg’s indicator values in floristic and phytosociological data sets respectively. Both methods are based on frequencies and averages of the indicator values within and among data sets. Main goal of proposed methods is to determine the thresholds to consider significant the observed variations. In the aim to relate the observed floristic variations to recent climatic changes, attention was focused on the Ellenberg’s indices dealing with the main climatic variables: heliophany, temperature and precipitation. Study-cases from Zannone island (Pontine archipelago, Mediterranean region), Inferno valley (Rome, Mediterranean region) and Braulio valley (Stelvio National Park, Alpine region) are reported. For Mediterranean data-sets, integration and adjustments to the Ellenberg’s indicator values have been adopted

AVAILABLE SOIL WATER CAPACITY AS A DISCRIMINANT FACTOR IN MIXED OAK FOREST OF CENTRAL ITALY

Soil water content is a critical factor in Mediterranean forest vegetation, especially in areas subjected to prolonged summer drought where winter and autumn rainfall are the main sources of water. Available soil water capacity (AWC) is the maximum amount of water available for plants that a soil could possibly contain. Each soil has a specific available water capacity, however, most of the published literature on AWC refers 10 agricultural settings, although the interaction between the soil and the vegetation dynamics has long been recognized. The aim of this study was to investigate whether this edaphic factor could be discriminant in species assemblage of communities belonging to the thermophylous oak forest (order Quercetalia pubescentis). Thirty-two vegetation relevés and soil profiles were carried out in five different sites, with a similar pluvio-thermic regime, located in the sub-coastal belt of Latium, Central Italy. From the physical\-chemical analyses of soil profiles, the AWC values, of the related relevés, were calculated. Multivariate statistical analysis was applied to the vegetation surveys, using Cluster Analysis from which a classification in three different clusters was obtained; subsequently the AWC values were grouped according to the c1assification obtained. Analysis of variance was used to test similarity and the output pointed out a significant difference among the three clusters (F=6.35;

AVAILABLE SOIL WATER CAPACITY AS A DISCRIMINANT FACTOR IN MIXED OAK FOREST OF CENTRAL ITALY

Soil water content is a critical factor in Mediterranean forest vegetation, especially in areas subjected to prolonged summer drought where winter and autumn rainfall are the main sources of water. Available soil water capacity (AWC) is the maximum amount of water available for plants that a soil could possibly contain. Each soil has a specific available water capacity, however, most of the published literature on AWC refers 10 agricultural settings, although the interaction between the soil and the vegetation dynamics has long been recognized. The aim of this study was to investigate whether this edaphic factor could be discriminant in species assemblage of communities belonging to the thermophylous oak forest (order Quercetalia pubescentis). Thirty-two vegetation relevés and soil profiles were carried out in five different sites, with a similar pluvio-thermic regime, located in the sub-coastal belt of Latium, Central Italy. From the physical-chemical analyses of soil profiles, the AWC values, of the related relevés, were calculated. Multivariate statistical analysis was applied to the vegetation surveys, using Cluster Analysis from which a classification in three different clusters was obtained; subsequently the AWC values were grouped according to the c1assification obtained. Analysis of variance was used to test similarity and the output pointed out a significant difference among the three clusters (F=6.35;

Soil water content as a disriminant factor in forest vegetation: preliminary results on sub-coastal mixed oak woodlands in central-southern Latium (central Italy).

Water resources and Vegetation, Napoli