Sacred natural sites and biodiversity conservation: a systematic review

Sacred natural sites (SNS) have gained recognition from conservationists, and are regarded as the oldest form of habitat protection in human history. Many case studies and literature reviews have been published on the subject. However, an updated and global-level synthesis on the effect of SNS on biodiversity conservation is still lacking. Here, we provide the first systematic review on SNS and biodiversity conservation, aiming to evaluate the effect of SNS across different: (i) continents; (ii) taxa; (iii) metrics. We checked 2750 papers and by applying inclusion criteria we selected 27 relevant papers. From these, we extracted descriptive data and 131 comparisons between SNS and Reference Sites. We applied vote-counting, multinomial and binomial post-hoc tests to the 131 comparisons. We found strong evidence that SNS have a positive effect on biodiversity, but also strong geographical and taxonomical biases, with most research focusing on Asia and Africa and on plants. We found that SNS have mainly positive effects on taxonomical diversity, vegetation structure and cultural uses of biodiversity. Our results strongly support the view that SNS have positive effects on biodiversity across continents and geographical settings, as found in a number of local studies and earlier overviews. These effects should be given official recognition in appropriate conservation frameworks, together with the specific forms of governance and management that characterize SNS. At the same time, further efforts are also required to fill the geographical and taxonomical gaps here highlighted, and to advancing our knowledge of SNS through more systematic research.