Evaluating weed diversity with indices of varying complexity in north‐eastern Italy

Abstract

Weed diversity is one of the focuses of attention of researchers, and it can be evaluated with different indices, mainly based on species richness and community evenness. In intensive cropping systems, much of the diversity is concentrated in semi-natural areas in the neighbouring habitats of arable fields. This study assessed weed diversity for seedbank and vegetation in an organically farmed valley in north-eastern Italy. Assessment was carried out with indices based on species abundance, together with Rényi diversity that also considers abundance distribution and Rao’s quadratic entropy, which considers dissimilarity between species. A complete quadratic entropy approach for weeds is described. It is known that landscape context may affect community structure, and as an example of application of diversity indices in weed research, the correlation with the surrounding landscape complexity was evaluated. Results show that a community can be relatively balanced with even just a few species. With diversity indices based on species abundance only, it is therefore difficult to quantify balance. The Rényi diversity can overcome this limit, and the quadratic entropy can isolate extreme communities. In conclusion, the diversity of a weed community can be better evaluated using more diversity indexes, and the quadratic entropy can provide new criteria for ranking the diversity and combine a number of traits into a single numerical descriptor. The correlation between landscape complexity and weed diversity is low but confirms that agro-environmental schemes should consider the management of fields and landscape together

Weed species diversity in organic and integrated farming systems

“…High species richness is expected to be positively correlated with high diversity and low dominance. However, a comparison of the number of species and species diversity in weed communities does not always give consistent results [37] and this was also found in our study. Diversity profiles (Rényi entropy) quantify diversity as a multidimensional concept with the use of the parameter [39].…”

“…According to popular belief, more diverse weed communities are less harmful to crops and easier to control [36,37]. In the exact sense, species diversity is defined as a combination of the number of species and their relative abundance [38].…”

“…One assemblage is more diverse than another if its diversity has been confirmed at all levels of If their profiles intersect, assemblages are incomparable and cannot be ordered with respect to biodiversity, because one of them is more diverse due to the presence of rare species (characterized by low abundance) than the other, and vice versa with regard to dominant species [41]. The Rényi profiles have been successfully used to assess the biodiversity of plant communities, while only a few authors have applied this method to compare weed communities [14,37,41] in different farming systems [42]. In a study conducted in Hungary, Z a l a i [42] used the Rényi diversity profiles to compare weed flora of organic and conventional maize and wheat fields.…”

Landscape complexity has limited effects on the genetic structure of two arable plant species, Adonis aestivalis and Consolida regalis

“…Our findings do not support the assumption that higher landscape heterogeneity always improves the genetic structure and increases the genetic diversity of arable plant populations. This corresponds to a recent study that failed to find any correlation between landscape structure and, in that case, functional diversity of arable plants (Otto et al ., ). (ii) The species populations of all studied regions exhibited hardly any genetic differentiation.…”

Effects of surrounding crop and semi-natural vegetation on the plant diversity of paddy fields

“…Environmental factors and management are the most important general drivers of plant species richness, abundance, and composition in agroecosystems [1][2][3][4]. Weeds, defined here as non-cultivated plants of crop fields, may hamper land management and food production but support biological diversity, diversify food webs and potential food resources, and improve soil health [5,6].…”