Intercalibration of assessment methods for macrophytes in lowland streams: direct comparison and analysis of common metrics

Abstract

The results of four macrophyte assessment methods (French Indice Biologique Macrophytique en Rivie`re, German Reference Index, British Mean Trophic Rank and Dutch Macrophyte Score) were compared, based on plant survey data of medium-sized lowland streams in Central Europe. To intercalibrate the good quality class boundaries two alternative methods were applied: direct comparison and the use of ''common metrics''. While the French and British methods were highly related (R 2 >0.75), the German RI showed less (0.20<R 2 <0.55) and the Dutch DMS least correlation (R 2 <0.10) with other methods. Of 70 macrophyte metrics tested only Ellenberg_N was considerably related to three of the national assessment methods, thus representing a potential common metric for intercalibration. Comparison of quality class boundaries via regression analysis using both intercalibration approaches revealed major differences between classifications of the French, German and British methods, which are, in addition, related in a nonlinear way.

The Macrophyte Index for Rivers (MIR) as an Advantageous Approach to Running Water Assessment in Local Geographical Conditions

“…It should be noted that the tested macrophyte methods were developed this century to evaluate the ecological status of water according to the requirements of the WFD [48]. The development of these methods was mainly focused on monitoring of the main factors responsible for the degradation of surface waters in Europe, which include eutrophication and, to a lesser extent, the hydromorphological factor [6,8,15,21,49]. It should be pointed out that the pH gradient in the studied rivers was very narrow, as the sandy lowland rivers of the whole Eastern European Lowlands have a rather uniform geology.…”

“…The results were based on the category of small and medium lowland rivers, but the correlations demonstrated can also be expected to apply to other types of rivers in Poland and abroad. Our analysis focused on this category because it represents a widespread type of rivers in Europe [28,49]. Moreover, the biodiversity of rivers of this type is higher than that of other rivers [37], and analyses based on rich biological material can better reflect the processes taking place in ecosystems.…”

The search for reference conditions for stream vegetation in northern Europe

“…Furthermore, pressure-impact relationships may not cover all types of single or combined pressures affecting biological communities. For example, stream macrophytes are well known for their response to nutrient pollution (see Birk, Korte & Hering, 2006), but the effect of other types of impairment are less well studied (Baattrup- Pedersen & Riis, 1999;Wright et al, 2003;Daniel, Bernez & Haury, 2006;O'Hare et al, 2006;Pedersen, Baattrup-Pedersen & Madsen, 2006). Consequently, the establishment of screening criteria and reliable thresholds for the selection of MDC or LDC sites for macrophyte assemblages is difficult.…”

“…Second, it is difficult to avoid subjectivity when using expert judgement. Thus limited knowledge on reference assemblages implies that the perception of what the reference condition represents differs among experts (Birk et al, 2006).…”

Patterns of aquatic macrophyte species composition and distribution in Bulgarian rivers

“…As stipulated by the European Water Framework Directive (WFD) 2000/60/EC (European Union, 2000) they are an obligatory element in the monitoring of ecological river quality. Macrophytes were included in assessment methods: French Indice Biologique Macrophytique en Riviere, German Reference Index, British Mean Trophic Rank, and Dutch Macrophyte Score (Birk et al, 2006). While high ecological status is determined via dominance of reference species in typespecific vegetation density, it is very important to determine whether patterns of aquatic macrophyte composition and distribution including cases of depopulation are a result of anthropogenic pressure or natural habitat variables.Local habitat characteristics determine river macrophyte communities, particularly light availability, current velocity, sediment patterns, and nutrient supply (Birk & Willby, 2010).…”