Identifying indicator assemblages as surrogates for conservation planning

Background/Question/Methods

Identification of appropriate conservation surrogates is essential to the design of effective protected area networks. Indicator species have been frequently used as surrogates, but their selection often requires detailed biological data that is time consuming or expensive to collect. Here we present a technique based on formal concept analysis (FCA) that bypasses these requirements and allows conservation planners to select appropriate surrogates based on easily measure landscape attributes and presence/absence data for potential indicator species. FCA utilizes order theory to clustering potential indicator species into groups based on these data. We applied this method using Nymphalid inventories carried out in seven localities of tropical dry forest in northeastern Colombia, differing in the type of human activities. We treated the 11 butterfly subfamilies as objects and six human activities as attributes and used FCA to identify potential indicator subfamily assemblages. We subsequently ranked these groups using Hasse Diagram Technique (HDT) in order to select the most suitable Nymphalid subfamily assemblage for conservation planning.

Results/Conclusions

FCA of the Nymphalid data resulted in 11 non-trivial groups, each corresponding to a particular subfamily assemblage appearing under certain human activities. Ranking criteria for HDT were the number of human activities, the number of non-indicative human activities, and the number of absent human activities, included for each group. Two groups were identified as suitable for conservation planning according to HDT. The highest ranked group included eight subfamilies, which occurred in areas close to human settlements but where any other human activities are absent. The second group corresponded to subfamilies present in areas where crops and cattle were absent. High human impact on the area made it challenging to find an assemblage that could indicate no human activity. However, the top ranked groups identified here can be used as indicators of less disturbed habitats, which makes them suitable surrogates for conservation planning. FCA combined with the HDT represents a valuable tool for identification of indicator assemblages, requiring only basic information on the presence of taxa and general attributes of the area occupied by them.