A variant of the dry‐weight rank method for botanical analysis of grassland with dominance‐based multipliers

Abstract

A new variant of the dry‐weight rank method for botanical investigation of grassland is described and its usefulness evaluated. Multipliers proportional to the dominance percentages of the three species with the highest dominance percentages are used instead of fixed multipliers. The method is theoretically more valid and applicable to a broader range of grasslands than the variants with fixed multipliers. It does not involve more costs and gives as good or better predictions of the dry‐weight percentages than the variants with fixed multipliers.

Effects of including forage herbs in grass–legume mixtures on persistence of intensively managed pastures sampled across three age categories and five regions

“…Briefly, this method involves visually ranking the three most dominant vegetation classes present in each quadrat with respect to their contribution to standing DM. Standard multipliers are then used to estimate the contribution of these vegetation classes to total pasture DM (Jones & Hargreaves 1979;Tothill et al 1992;Nijland 2000). This method may lead to an underestimate of the contribution of minor species (Lavorel et al 2008), which are better detected in ground cover assessments.…”

Botanical survey of perennial ryegrass-based dairy pastures in three regions of New Zealand: implications for ryegrass persistence

“…The proportion of perennial ryegrass, other sown grasses, unsown grasses, legumes, sown herbs and unsown broadleaved weeds in the pasture at the time of sampling was estimated using the BOTA-NAL method (Tothill et al 1992;Nijland 2000) in …”

Integrating models of relative abundance of species with the dry‐weight‐rank method for the botanical analysis of forest understorey vegetation

“…This effect can be identified in the differences of m q values across k ‐values in vegetation zones for large values of Q (Table 5) . Adjustments in the values of the DWR coefficients due to the dominance exerted by the most abundant species have been proposed by Scott (1986) and Nijland (2000). The k‐ values for the Power‐fraction model in this study are representing highly diverse plant communities, where the dominance percentage of the most dominant species is 9–18% (Figure 1).…”

“…The principal shortcoming of the DWR method is that scoring three ranks cannot satisfactorily explain the distribution of species in plant communities where the dominance level of the most abundant species is lower than in typical grassland swards. The variant of the DWR method described by Nijland (2000) utilizes coefficient values proportional to the abundance percentages of the three most abundant species. Although this approach improves the accuracy of the DWR method in predicting the botanical composition of grassland swards, it is considered that it would neglect the least abundant species in plant communities where the dominance of the most abundant species is low.…”