Fajszáma

Fajszáma is a Hungarian term that denotes the number of distinct species observed in a defined area, sample, or data set. In ecological work it is the basic expression of species richness, recording how many different species are present without regard to their abundances. The concept is widely used in Hungarian biodiversity studies to characterize the diversity of plants, animals, fungi, or other taxonomic groups within a given scope.

The meaning of fajszáma varies with the spatial scale. It can refer to local species count (alpha fajszáma), a broader regional total (gamma fajszáma), or comparative counts across different habitats. Because the value depends on how intensively researchers search and which taxa are included, comparisons between sites or times require standardization of sampling effort and taxonomic effort. Methods such as standardized surveys, species inventories, and the use of rarefaction or extrapolation techniques help make fajszáma more comparable across studies.

Measurement typically involves defining the sampling frame, conducting surveys or compiling lists of observed species, and ensuring consistent taxonomic treatment. Limitations include uneven detectability among species, cryptic taxa, and varying taxonomic expertise, all of which can under- or overestimate the true fajszáma. Despite these caveats, fajszáma remains a practical and widely used indicator of biodiversity.

Applications encompass conservation planning, environmental impact assessments, and long-term biodiversity monitoring. As a straightforward metric, it is often complemented by other measures of diversity (such as evenness, functional diversity, or phylogenetic diversity) to provide a fuller picture of ecological health.