Quantifying the effects of nutrient addition on community diversity of serpentine vegetation using parametric entropy of type α (original) (raw)
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Quantifying the effects of nutrient addition on the taxonomic distinctness of serpentine vegetation
Plant Ecology, 2005
Traditional diversity indices summarize the information about the relative abundances of species within a community without regard to differences between species. However, intuitively, a community composed of dissimilar taxa is more diverse than a community composed of more similar taxa. Therefore, useful indices of diversity should account for taxonomic relations among species. In this paper, a new parametric diversity index that combines species relative abundances and their taxonomic distinctiveness is used to quantify the way in which soil fertilization affects the diversity of a garigue community on ultramafic soils of Tuscany (central Italy). Results show that, while ultramafic soils generally host plant communities of limited taxonomic diversity with respect to similar communities on other substrates, fertilization significantly enhances the biomass production of species that are not exclusive to ultramafic soils. As a consequence, if diversity is measured combining species relative abundances with their taxonomic distinctiveness, nutrient addition tends to increase the diversity of ultramafic communities.
2003
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 of nitrogen, phosphorous and potassium were analyzed by a permutation-based approach. Phosphorus addition induced a significant increase in vegetation cover, and the observed changes in total plant cover persisted years after the cessation of fertilization. Plant species richness showed marked fluctuations during the experiment, but these were not related to any treatment. Although six years did not allow a robust test of the relations between climate and vegetation, some interesting observations were obtained. Total vegetation cover, a surrogate measure for community biomass, was positively related to the amount of rainfall in the whole period of the growing season, an often observed relationship in Mediterranean-type ecosystems. Species richness was positively related to the mean temperature of spring, and negatively related to mean spring temperature indicating that a warm and xeric spring season may induce local extinction of some species. Species of the community responded differently in relation to climate and phosphorus addition. Many species were positively influenced by phosphorus addition; however, in some annual species the effect disappeared with the cessation of fertilization, whereas in some perennial species it persisted in the following years.
Agriculture, Ecosystems & Environment, 2003
Direct measurement of soil biodiversity is expensive, and therefore a substitution of measurement by indication is desirable. We analysed three large datasets for the potential to predict the diversity of soil faunal groups from other parameters. The datasets represent different spatial scales, namely grassland nematodes on an European scale, forest collembola on a regional scale, and grassland ants on a local scale. We tested two groups of parameters as possible surrogates for species richness: (1) environmental parameters, such as climate, soil and vegetation characteristics, and (2) community parameters, such as higher taxon richness, indicator taxa, and maximum dominance.
Effects of Nutrient Addition on Community Productivity and Structure of Serpentine Vegetation
Plant Biology, 1999
The effects of a nutrient addition experiment on the plant biomass of garigue vegetation on ultramafic (serpentine) soils in Tuscany, Italy, were investigated. Although community composition was not significantly changed, fertilization had a significant positive influence on biomass production. The most affected species groups were woody species (chamaephytes and phanerophytes), annual grasses and annual forbs; the biomass increase of the perennial grasses and perennial forbs was statistically not significant. Soil extractable elements differed for calcium and potassium in the plots where they were added; sodium and nickel extractabilities were reduced by calcium addition due to the increased soil pH. Biomass production was linked more to major nutrient addition than to reduced nickel extractability, confirming that serpentine vegetation of Tuscany is mainly affected by nutritional stress rather than soil heavy metal content. The addition of calcium had a low effect on primary production of these ultramafic soils.
Plant Biosystems, 2011
The present study deals with the grassland complex of communities which may be found on the limestones in the south-eastern Alps; these communities show in fact a particular interest for their high biodiversity degree and for their importance for the traditional land-use economy of the south-European mountain regions. Phytosociological relevés corresponding to well-defined plant associations have been used in order to get information on the relationships among plant species diversity, biomass, chorotypes, pollination types, functional strategies and soil characteristics. The analysis was carried out both along an altitudinal and a soil evolution gradient. The analysis of the correlations among the variables and the application of the principal component analysis shows a positive correlation between soil parameters and biomass, eurichory, anemogamy and C- and R-strategies; on the contrary, a negative correlation among stenochory, entomogamy and S-strategy with the soil evolution seems to be present. This article shows how the phytosociological approach can be used to get information and knowledge on the correlations between several variables useful to understand the complex nature of the plant communities in order to support management plans.
Comparison of diversity indices applied to macrophyte incidence-based data
Brazilian Archives of Biology and Technology, 2012
In this work, a recently proposed diversity index based on Patil and Taillie parametric diversity measure (or Tsallis entropy), S q* , was applied to samples (presence-absence data) of macrophytes from the Itaipu Reservoir, Brazil. This new index was the value of the family of indices S q for a specific evenness of a sample. Results demonstrated that the Shannon index and species richness showed expressively high correlation with the S q* ; however, the evenness had low correlation coefficients with the index S q* , indicating that S q* was particularly sensitive to rarity and species richness. On the other hand, the weak correlations of this index with evenness demonstrated that it was less sensitive to species relative abundances.