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Without robust and unbiased systems for monitoring, changes in natural systems will remain enigmatic for policy makers, leaving them without a clear idea of the consequences of any environmental policies they might adopt. Generally, biodiversity-monitoring activities are not integrated or evaluated across any large geographic region. The EuMon project conducted the first large-scale evaluation of monitoring practices in Europe through an on-line questionnaire and is reporting on the results of this survey. In September 2007 the EuMon project had documented 395 monitoring schemes for species, which represents a total annual cost of about 4 million, involving more than 46,000 persons devoting over 148,000 person-days/year to biodiversity-monitoring activities. Here we focused on the analysis of variations of monitoring practices across a set of taxonomic groups (birds, amphibians and reptiles, mammals, butterflies, plants, and other insects) and across 5 European countries (France, Germany, Hungary, Lithuania, and Poland). Our results suggest that the overall sampling effort of a scheme is linked with the proportion of volunteers involved in that scheme. Because precision is a function of the number of monitored sites and the number of sites is maximized by volunteer involvement, our results do not support the common belief that volunteer-based schemes are too noisy to be informative. Just the opposite, we believe volunteer-based schemes provide relatively reliable data, with state-of-the-art survey designs or data-analysis methods, and consequently can yield unbiased results. Quality of data collected by volunteers is more likely determined by survey design, analytical methodology, and communication skills within the schemes rather than by volunteer involvement per se.

Monitoring of biodiversity at the level of habitats is becoming increasingly common. Here we describe current practices in habitat monitoring based on 150 schemes in Europe. Most schemes were initiated after 1990 in response to EU nature directives or habitat management/restoration actions, with funding mostly from European or national sources. Schemes usually monitor both the spatial distribution and the quality of the habitats, and they frequently collect data on environmental parameters and potential causes of changes. Many schemes are local or regional rather than national or international in scope, and sampling effort varies greatly across spatial and temporal scales. Experimental design is used in half of the schemes, however, data are rarely analysed by advanced statistics. Most schemes require two months or less per year in manpower and are typically run by professionals rather than by volunteers. Estimated salaries plus equipment costs average 650,000 Euro per year per scheme, and add up to 80 million Euros annually. Costs are particularly high for schemes based on European or international law and for schemes funded by European or national sources. Costs are also high in schemes in which sampling sites are selected subjectively rather than based on sampling theory, and in schemes that do not use field mapping or remote sensing to document spatial variation in habitats. Our survey demonstrates promising developments in European habitat monitoring but also underlines the need for better spatial coverage, documentation of spatial variaton, improved sampling design and advanced data analysis. Such improvements are essential if we are to judge progress towards the 2010 biodiversity targets.