A review and statistical assessment of the criteria for determining cave significance

Determining the significance of caves is challenging due to a lack of consensus on which parameters to consider and their relative importance, in addition to difficulties in applying the parameters in a repeatable way. However, classifying caves by levels of significance is unequivocally important because it allows the prioritization of caves for future environmental protection. In countries where the subsurface belongs to the government, such as Brazil, the decision process is coordinated at the government level and a comprehensive approach balancing environmental protection and economic/social interests should be applied. Brazil has the most comprehensive set of criteria for assessing the significance of caves, encompassing parameters applied in other countries. A sample of 401 Brazilian caves in limestone and iron-rich rocks was analysed statistically to infer the relative frequency of each criterion in assigning significance to caves. The analysis included 70 parameters; 30 were present in caves, but on average less than five of these parameters occurred together at each cave. Subjective parameters tended to be less represented. Biotic parameters were dominant and both abiotic and biotic parameters displayed a correlation with length and area, suggesting that these parameters could be good indicators of cave significance. Applying the set of criteria proposed by the Brazilian government to our sample, there was no marked difference between caves in different rock types. A better approach to defining cave relevance is required, with an emphasis on science-based parameters.