JME 2003 2
Patterns of landbird species composition in Italy: A chorological approachfocusing on trends and contra-trends along the peninsula
Corrado Battisti, Anna Testi
The aim of this study was to analyse chorological patterns of breeding landbirds to find ecogeographical factors responsible fortrends, contra-trends and discontinuities along the Italian peninsula. The study was conducted in continental (northern) and penin-sular (central-southern) Italy. Italy was subdivided into 27 latitude bands from North to South. For each band, the proportionsamong the breeding landbird species belonging to different chorotypes was calculated and correlated with the latitude, the maxi-mum altitude and the area of Mediterranean climate. The Cluster Analysis and the Correspondence Analysis performed on thechorotypes matrix showed a clear subdivision into two groups, i.e. the two main Italian bioclimatic regions (Eurosiberian andMediterranean). Along the Italian peninsula, the proportion of northern chorotypes (Holarctic, Eurasiatic, Eurosiberian, Eurocen-tral-asiatic, European) was positively correlated with latitude and maximum altitude, and negatively with the area of Mediterra-nean climate. The southern chorotypes (Eastern-Palearctic, Olopalearctic, Eurocentralasiatic-Mediterranean, Euroturanic-Medi-terranean, Mediterranean) behave in specular fashion. The European species represent the intermediate chorotype between thenorthern group and the southern one.The two main chorological groups divide Italy into two sectors: One continental, north of the bioclimatic boundary between Medi-terranean and Eurosiberian regions, and the other peninsular, to the south. Calabrian subpeninsula is chorologically separate fromthe rest of the Italian peninsula. Furthermore, areas with large changes in bird community composition emerged both in the Corre-spondence Analysis and in the Diversity Indices: 1) at the level of the bioclimatic boundary; 2) at the Southern tip of the AbruzzoApennines; and 3) at the border of the Calabrian subpeninsula.ninsulas from mainland to the
Keywords: Chorology, Italy, landbirds, peninsula effect.
Community dynamics of serpentine vegetation in relation to nutrient additionand climatic variability
Alessandro Chiarucci, Ilaria Bonini, Lorenzo Fattorini
To investigate the effects of nutrients and climate on community composition and structure of serpentine vegetation in Tuscany,Italy, a fertilization experiments was carried out over a period of six years. Response curves of vegetation to the addition ofnitrogen, phosphorous and potassium were analyzed by a permutation-based approach. Phosphorus addition induced a significantincrease in vegetation cover, and the observed changes in total plant cover persisted years after the cessation of fertilization. Plantspecies richness showed marked fluctuations during the experiment, but these were not related to any treatment. Although six yearsdid not allow a robust test of the relations between climate and vegetation, some interesting observations were obtained. Totalvegetation cover, a surrogate measure for community biomass, was positively related to the amount of rainfall in the whole periodof the growing season, an often observed relationship in Mediterranean-type ecosystems. Species richness was positively related tothe mean temperature of spring, and negatively related to mean spring temperature indicating that a warm and xeric spring seasonmay induce local extinction of some species. Species of the community responded differently in relation to climate and phosphorusaddition. Many species were positively influenced by phosphorus addition; however, in some annual species the effect disappearedwith the cessation of fertilization, whereas in some perennial species it persisted in the following years.
Keywords: climate, drought, serpentine soil, species diversity
Variation in shrub structure and species co-occurrence in the Mediterranean maquis
Loretta Gratani, Antonio Bombelli, Francesca Covone
The structure of the Mediterranean maquis developing inside the Presidential Estate of Castelporziano (S-SW of Rome) was due tomixture of different evergreen species. On an average six species co-occurred in shrub formation, the highest frequency being ofCistus incanus (80%), Erica multiflora (73%), Smilax aspera (53%) and Quercus ilex (50%). Discriminant analysis indicated thatshrub volume was the most discriminating trait among the analysed shrub traits (height, volume, crown height, crown depth, majoraxis and minor axis of the crown, crown projection at soil, crown volume, leaf area index). On the base of shrub volume, threedifferent sizes of shrubs were defined by cluster analysis: small (S), medium (M) and large (L) shrubs and they were characterisedby a volume of 1.9±1.5m3, 13.1±4.8 m3 and 34.9±8.8 m3 respectively. The considered maquis stand was constituted by 1050±300shrubs ha-1, corresponding to a total shrub volume of 7793±1401 m3 ha-1; the frequency of S, M and L shrubs was 63%, 31% and 6%respectively. Number of species increased from S to L shrubs: S were constituted by 4.8±1.7 species, M by 7.4±1.6 and L shrubs by8.3±0.8. Cistus incanus, Daphne gnidium, Erica multiflora, Pistacia lentiscus and Rosmarinus officinalis of small height (< 1 m)occurred mainly in S shrubs, while Arbutus unedo, Erica arborea, Phillyrea latifolia and Quercus ilex (height = 1.4±0.3 m) inmedium and large shrubs. The impact of shrub size on the Mediterranean maquis resulted in a patchiness of microclimatic varia-tions showing the buffering effect of the shrub size: 78% of the study area was covered by shrubs having 4% and 94% reduction ofair temperature and light transmittance respectively, and 10% and 165% increase of air humidity and soil water content respecti-vely. The remaining 22% of the study area was uncovered and directly subjected to the climate of the zone.
Keywords: shrub structure, leaf area index, Mediterranean maquis, microclimate.
Ecological study of the vegetal component in the terrestrial ecotones of central Italy
F. Rastelli, L. Staffolani, K. Hruska
Ecological analysis of the flora of central Italian terrestrial ecotones demonstrates two flows of species in opposite directions alongthe gradient of anthropization in order to connect the anthropized areas with the natural ones. The single species reacts to thechanges of the ecological conditions with morphological and anatomical adaptations. Reduction of habitus and shortening of thelife cycle took place. The flows can be identified as the results of dynamic processes of apophytization and of anthropophytization.The first assures the survival of natural ecotone species and fosters their movements towards anthropized ecotones. The secondfacilitates the spread of plants with wide distribution and that of species with multiple ecological strategies from strongly anthro-pized ecotones to seminatural and natural ones. The establishment of the latter causes the banalization of the ecotonal flora andthe presence of fairly homogeneous patches dominated by some populations of the Graminaceae and the Compositae families. Inthe ecotones with strong human disturbance, the species with multiple strategies are selected. Continous exchanges of speciesbetween the ecotones support the connectivity among settlements exposed to different intensity of the human impact. The linkbetween these exchanges of species and the biodiversity of the ecotones is confirmed. The greates richness in species is observedin the moderately anthropized ecotones as the result of the coexistence of plants coming from different ecosystems.
Keywords: diversity, ecological analysis, ecological strategies, ecotones, flora, human impact, Italy