Species status assessment and monitoring in the Belgian continental region: general options & examples from insects Philippe Goffart & Marc Dufrêne (Ministère de la Région wallonne / CRNFB)
Introduction Context The assessment of species status is required every six years within the context of the Habitat Directive and the Natura 2000 network Needs It implies the development of : appropriate monitoring schemes adapted and reliable method to estimate trends
General options Range mapping Data selected within one of three windows periods according to the completeness of the data so as to fit to the rhythm of 6 years for the reporting: 2001-2006 (6 years) first choice, if possible 1995-2006 (12 years) next choice 1989-2006 (18 years) last choice, if poor sampling
General options Trends analysis General monitoring Comparison of data from two six year periods, if possible Otherwise, expert judgement General monitoring Minimum required: visit to the known localities... ...at the right time of the year… ...once every six years all of them if < 60 localities 80% of them if 60 - 90 localities 70% of them if 90 - 120 localities 60% of them if > 120 localities
Trends analysis Development of a new method Principles To estimate changes in: range size observation rate per visit …between two six years periods of a survey or a monitoring scheme. Comparison achieved on grid cells visited at the right time at both periods (to neutralize the spatio-temporal heterogeneity of sampling).
Results for butterflies Table 1. Trend analysis with classical and new methods of comparisons for three N2000 butterfly species (G test for goodness of fit).
Specific monitoring schemes Designed for some species with restricted range and fluctuant (meta)populations Example: Marsh Fritillary (Euphydryas aurinia) Monitoring by counts of caterpillar nests at the end of summer in main colonies (13 years)
Marsh Fritillary (Euphydryas aurinia) 1995 - 2000 2001 - 2006 Range rather stable between the two 6-year periods (Δ% = 0%)... But strong fluctuations within individual colonies and important decline during the last two seasons Example of two populations
Other species ... similar approach when data available are or expert judgment many problems for mammal species (bats and others species from Annex 4 and 5) that are indeed not well known. Only beaver is well monitored.