Paola Ganis

Toward a framework of integrated knowledge of terrestrial vegetation system: The role of databases of phytosociological relevés

Abstract In this article, we consider the meaning of the phytosociological relevé of the Braun-Blanquets approach as a source of biodiversity matrices. We stress the importance of phytosociological relevé for the integrated vegetation studies dedicated to understand the vegetation system and its ecosystem role at different hierarchical levels. We review the state of the art of building databases of the Italian vegetation under the perspective to develop a knowledge database of Italian vegetation based on formal ontologies. This would constitute a node in the possible network of knowledge databases of European Union and of the world that is proposed within the International Association of Vegetation Science.

Riparian Salix alba: Scrubs of the Po lowland (N-Italy) from an European perspective

Abstract This paper deals with riverine Salix alba – scrubs of the Po plain (northern Italy). They were compared with analogous formations of many other European countries to study similarities and differences. Demographic concentration and intense human activities (agriculture, industry) in the basin of the Po River are among the highest in Europe, with the remarkable consequence that all hygrophilous woods and bushes contain a high number of alien species. The units dominated by Salix alba were analyzed. Their originality in comparison with the similar associations of Mediterranean, central- and SE-Europe was emphasized.

Airborne pollen calendar for Trieste (Italy), 1990–2004

Daily airborne pollen grains were collected in Trieste (1990–2004) using a Hirst‐type trap. A large quantity of pollen grains was found, the mean annual total being 48 082 grains. Daily counts were particularly high between March and June, the highest values being recorded between April and May. A total of 123 different pollen taxa from 80 families were identified. Almost half of the total pollen content came from introduced trees and shrubs, one fifth from natural woodlands, and one quarter from herbaceous taxa. This composition reflects the ornamental and ruderal flora of the town, as well as the natural vegetation surrounding the urban area. The pollen richness of both mesophilous and thermophilous taxa reflects the complexity of this zone, considered a “crossroad” of species of different chorological types. Total daily pollen concentrations were positively correlated with temperatures only in the pre‐peak period. The main taxa, except for Urticaceae, Pinus and Gramineae, displayed positive correlations with temperatures both in the main pollen season and in the pre‐peak period. The annual pollen sum of Ostrya was negatively correlated with total rainfall of the previous summer, and that of Pinus was negatively correlated with the winter severity.

Probabilistic Methods in Classification: A Manual for Seven Computer Programs

The aim of a general-purpose classification may be expressed as the definition of a set of classes such that class membership is highly predictive of as many attributes as possible. Instead of having to describe each object by listing the values of each of its attributes, one aims to encapsulate as much as possible of this description in the simple statement that the object is a member of this or that class.

A diachronic approach to assess alien plant invasion: the case study of Friuli Venezia Giulia (NE Italy).

Abstract Direct experimental methods for measuring plant invasiveness based on generative vs. vegetative reproductive mechanisms have already been proposed in the literature. In the present work, an indirect method to measure plant species invasion using historical and current data from various sources is described. This method involves a diachronic approach whereby the speed of plant invasion can be measured as the rate of new site colonisation by species over time. The study was conducted in Friuli Venezia Giulia (NE Italy). Field data, herbarium collections and data from the literature since the late 19th century were used to gather information on the presence or absence of some alien species through time, and a simple index to measure the invasion rate in the territory was developed. Results show that the diachronic approach allowed the identification of species that are generally recognised as more invasive already in other studies.

On the application of numerical and computer methods in plant taxonomy and plant geography: an integrated information system for data banking and numerical classifications and ordinations

Abstract The most relevant problems in plant taxonomy and geography for which numerical taxonomy is used are briefly discussed. The attention is focused to the problems of geographic variation within species and clinal variations in respect to ecological factors. Examples of applications to morphological data of Euphrasia proved the existence of a clear geographical pattern of variation within E. minima which shows a decrement of sharpness of the leaves teeth along an East-West gradient and along an elevation gradient. The pattern of distribution of Italian species of Euphrasia in respect to three factors—light, elevation and soil drainage—reflects very well the ordination and the classification obtained by numerical methods based on morphological characters. A software for phytogeographic data is illustrated with an example of application to a floristic data bank of the Italian Karst region. It allows to cluster geographic units and to define the discriminating species at different hierarchical levels.

The role of vegetation analysis by remote sensing and GIS technology for planning sustainable development: A case study for the Santos estuary drainage basin (Brazil)

The role of vegetation analysis by remote sensing (RS) and Geographical Information System (GIS) technology to support plans for sustainable development is discussed through a proposal of an index of ecosystem “integrity” or of regeneration capacity. The index is based on the vegetation “mass” of a given land cover type and the capacity that such mass has to contrast soil erosion. The index is therefore taking into account the effects of human activities and not merely the state of ecosystems in terms of their components. It would be very difficult, if not impossible, to calculate the proposed index without RS and GIS techniques. These allow, respectively, to collect and to analyze the spatial data at relative low cost and in relatively short times. Time and money are the limiting factors for all the management plans. As an example of application, we have calculated the index for the Santos estuary drainage basin (Brazil) selected as a case study within the ECOMANAGE project funded by European Commission. The area was chosen because of its great economic importance and for relevant environmental problems (industrial pollution and urbanization pressure) that could limit the development. For estimating the relative vegetation mass, we have used the Leaf Area Index, while for the soil erosion, we have used the revised universal soil loss equation model. The maps of ecosystem integrity produced by the application of the index may be very useful to guide the planners in the development of the urbanization process that is threatening the “Mata Atlantica” and the mangrove forests.

Improving knowledge of urban vegetation by applying GIS technology to existing databases

ABSTRACT Question: Can we improve the knowledge of urban vegetation using data from ongoing floristic and management projects with a data mining approach? We have two questions: 1. How strong is the relationship between land cover pattern and the species composition of vegetation? 2. What is the relationship between land cover pattern and species richness? Location: Trieste, northeastern Italy. Methods: Using land cover maps and GIS we characterized the cells of a floristic project grid by percentage cover of land cover types. We applied Canonical Correlation Analysis to test the correlation between floristic composition of the cells and land cover. We classified the cells by clustering methods, based on land cover description. With these clusters, we analysed the variation of species composition of urban vegetation along a gradient of urban density. We used Jaccards similarity index to compare floristic composition of the clusters with the floristic composition of the homogeneous cells with respect to the land cover types. To answer question 2, we calculated land cover heterogeneity with the Shannon index and correlated the number of species in clusters with land cover heterogeneity and urban density. Results: Each land cover type contributes to species richness and species composition of the clusters. Species richness decreases significantly and linearly as urban density increases and land cover heterogeneity decreases in the clusters. Conclusions: A data mining approach can combine different existing projects to improve knowledge of the urban vegetation system. The methods we have applied offer tools to answer the specific questions mentioned above. Nomenclature: Poldini et al. (2001).

Measuring the effects of human impact on vegetation by integrating phytosociology and remote sensing in a fuzzy set approach

Abstract The response of fragmented vegetation to human impact has been analysed in degraded and degrading areas in Tanzania (Lake Manyara). Phytosociology was integrated with GIS and remote sensing data as follows: (1) a land cover/land use map was obtained by analysing remote sensing data and conducting field verification; (2) phytosociological relevés were randomly sampled in woodland vegetation patches using the map; (3) the pattern of land cover/land use around the relevés was described; (4) gradients of land use intensity (human impact) were obtained based on the descriptions; (5) the response of vegetation types to impacts of gradients was calculated using fuzzy set theory. Two complementary gradients of human impact were defined based on land cover/land use analysis of the remotely sensed data: one related to cultivation intensity and the other to grazing intensity. Response functions of vegetation types (defined by numerical classification) to these gradients demonstrated that the vegetation types are strongly related to the degree of human impact and that the corresponding vegetation patches show different degrees of permeability to the species of the surrounding landscape. Nomenclature: Anon. 1954–.

Pedodiversity deserves attention in plant biodiversity research

We suggest that pedodiversity, an expression of environmental heterogeneity, should deserve the attention of plant ecologists interested to study the spatial pattern of plant biodiversity at different scales. Using the FAO pedological and the IUCN-WCMC biological data bases of the world countries, we show that the prediction on plant biodiversity (number of vascular plants) improves significantly when the extent of the area is combined with pedodiversity in a multiple polynomial regression. Partial correlation analysis proves that, by removing the effect of pedodiversity, the correlation “number of species–area” remains statistically significant for the tropical countries while it loses significance for the countries outside the tropics.