So it is necessary to select groups of organisms that can give adequate information and sampling methods that are reliable, rapid and economical.

Abstract

A A b b s s t t r r a a c c t t

The depths changes brought by the rapid economical development, that took place in the second half of the twentieth century, caused the transformation of the natural and seminatural environments with the consequent decay of the biodiversity. The evaluation of such parameter become, therefore, a pressing theme. Accordingly, the question of studies is increasing, but, on the other hand money and time resources to be employed are very limited.

So it is necessary to select groups of organisms that can give adequate information and sampling methods that are reliable, rapid and economical.

Arthropods are considered a good indicators of biodiversity, because they are a key component of the earth habitats. They answer very quickly to the environmental changes and, generally, they comprise suprageneric taxa with a great number of species. In the light of this, it is been decided, for the present research, to study a particular group of Insects, the dung beetles. Moreover the consortium IUBS-UNESCO listed dung beetles among key-groups for the inventory and the monitoring of the terrestrial environments biodiversity in the program Diversitas promoted to world level.

The sampling took place in the Regional Park of the Maremma, a natural area characterized by the presence of wild and semi-wild bovine and equine breeding, therefore particularly proper for the analysis. Five places characterized by a different vegetable coverage were chosen inside the Park. Six pitfall-traps (three baited with bovine dung and three with equine dung) were placed in three localities usually frequented by the livestock. In the remaining two stations, sporadically frequented only, but interesting by an environmental point of view, were placed two traps only, one baited with bovine dung and the other with equine dung. The traps were serviced fortnightly and the collected beetles have been determined and preserved not mounted in special couches. The research lasted one year, from June 2003 to May 2004 and it is intended to:

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verify that the sample was representative of the population and appropriate for the study of the space-time distribution;

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relief meaningful differences among the five sites of sampling by analyzing the structure of each population;

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notice possible differences in the traps if they were baited with different types of dung, always making reference to the structure of the population.

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Abstract

The data were analyzed by developing a first quantitative study on the number of taxa (56) and of individuals (36779), which has underlined a seasonal course that presents a high trend in spring and autumn and a low trend in winter and summer. The examined populations have also been characterized using the Shannon-Weaver index: the calculated value for the principal three sites showed a good biodiversity (H’=2.77, 2.45, 2.24 respectively) and the open pasture results to have a high biodiversity (H’=2.77). For the other two sites we have had a good approximation of the faunistic situation in both of them, even if the lower number of placed traps could have invalidated the result.

Non parametric analysis (Multidimensional Scaling and Cluster Analysis) and statistical test (Kruskal-Wallis test) allow us to affirm that the peculiar environmental characteristics but not the type of dung used for bating the traps, affect the population present in the environment.

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