Introducing an abundance index for assessing weed flora in survey studies

Abstract

This study was carried out to propose a simple abundance index (AI) of weed species, to describe the ranking of weeds in weed communities, and to evaluate weed flora. Based on a 4 year weed survey program conducted in Tehran province, the Thomas methodology for determining the relative abundance (RA) in weed communities was applied and a new, improved method (called the AI method) was introduced. Sixty-one irrigated wheat fields were selected using a stratified sampling procedure.The boundaries of each county in the province formed the strata. For the Thomas method, the data were summarized for each county using five quantitative measures for determining the RA of each species. For the AI method, three quantitative measures were used, including frequency, uniformity, and mean field density. In the Thomas method, the mean field density had a significant role in determining the RA of a species, while the frequency and uniformity had a less significant role. However, for determining the AI, the frequency and uniformity had a higher value than the mean field density. Higher values for these two parameters for a particular species indicates that this species was more compatible with the soil and climate conditions in which it was growing, while higher values for the mean field density for a particular species indicates that the species had a higher competitive or reproductive ability than other species. In the Thomas method, the weed species with a low mean density were less abundant and not a serious weed for agroecosysytems but, in the AI method, an invasive weed could be detected before the colonization stage.

Regional Mapping of Perennial Weeds in Cotton with the Use of Geostatistics

“…Thomas (1985) introduced weed relative abundance (RA), which is estimated by summing relative frequency, relative uniformity, and relative density so as to assess weed importance. Moeini et al (2008) proposed the abundance index (AI) in order to introduce a methodology capable of demonstrating the compatibility of weeds with soil and climatic conditions that other indexes failed to show until then. Furthermore, this index evaluates the weed populations and describes the weed ranking in an area.…”

Observation of Weed Species, Frequency and Density in Common Barley (Hordeum vulgare L.) Fields of Diyarbakir, Turkey: A Case Study

“…Identification of weed distribution can be a significant point in the weed control in the common barley production. Monitoring weeds in the studied areas will help to define the implementation of appropriate management preventions (Moeini et al 2008). Veisi & Moeini (2015) found that C. arvense and C. depressa species, also Avena, Galium, and Vicia, a genus which is the prominent weeds in Kermanshah common barley areas, observed in the Diyarbakir too, this indicates that these weeds can be a trouble in different ecosystems.…”

Weeds distribution and abundance in irrigated fields of White Nile State

“…Mean field density (MFD), frequency (F) and uniformity (U) were the only quantitative measures used for abundance index (AI) determination (Moeini et al, 2008 Abundance Index (AI k ) = MFD k + F k + U k…”

“…High value of MFD of species illustrate it has more competitive ability than other species, while the high value of Frequency and Uniformity characterize its compatibility with the soil and climate conditions (Moeini et al, 2008).…”

“…25, 25.56 and 22.16 Relative Dominance were the most important weeds. Moeini et al, (2008) showed that 87 weed species were observed within irrigated wheat fields in Tehran province. The most important broadleaved weed species were Descurania sophia, Polygonum aviculare, Fumari availlantii Loisel.…”