Reconciling Mining with the Conservation of Cave Biodiversity: A Quantitative Baseline to Help Establish Conservation Priorities.

Rodolfo Jaffé,Clóvis Maurity,Xavier Prous,Guilherme Oliveira,Vera L Imperatriz-Fonseca,Robson Zampaulo,Iuri V Brandi,Tereza C Giannini,José O Siqueira,Judi Hewitt

doi:10.1371/journal.pone.0168348

Abstract

Caves pose significant challenges for mining projects, since they harbor many endemic and threatened species, and must therefore be protected. Recent discussions between academia, environmental protection agencies, and industry partners, have highlighted problems with the current Brazilian legislation for the protection of caves. While the licensing process is long, complex and cumbersome, the criteria used to assign caves into conservation relevance categories are often subjective, with relevance being mainly determined by the presence of obligate cave dwellers (troglobites) and their presumed rarity. However, the rarity of these troglobitic species is questionable, as most remain unidentified to the species level and their habitats and distribution ranges are poorly known. Using data from 844 iron caves retrieved from different speleology reports for the Carajás region (South-Eastern Amazon, Brazil), one of the world's largest deposits of high-grade iron ore, we assess the influence of different cave characteristics on four biodiversity proxies (species richness, presence of troglobites, presence of rare troglobites, and presence of resident bat populations). We then examine how the current relevance classification scheme ranks caves with different biodiversity indicators. Large caves were found to be important reservoirs of biodiversity, so they should be prioritized in conservation programs. Our results also reveal spatial autocorrelation in all the biodiversity proxies assessed, indicating that iron caves should be treated as components of a cave network immersed in the karst landscape. Finally, we show that by prioritizing the conservation of rare troglobites, the current relevance classification scheme is undermining overall cave biodiversity and leaving ecologically important caves unprotected. We argue that conservation efforts should target subterranean habitats as a whole and propose an alternative relevance ranking scheme, which could help simplify the assessment process and channel more resources to the effective protection of overall cave biodiversity.

Highlights

Decisions about which lands to allocate for conservation often involve conflicting interests between industry, local communities, and environmental protection agencies [1]
While we found significant spatial autocorrelation in species richness across most of the analyzed spatial scales, the presence of rare troglobites, presence of troglobites, and presence of bat populations only showed significant spatial autocorrelation at small and intermediate spatial scales (Fig 2)
In all cases spatial autocorrelation decreased with increasing spatial scale, and did not differ from the random expectation when reaching the maximal extent of our study area (Fig 2)

Summary

Introduction

Decisions about which lands to allocate for conservation often involve conflicting interests between industry, local communities, and environmental protection agencies [1]. Such conflicts can be acute in the mining sector, given that mineral resources are not uniformly distributed but rather spatially clustered, implying that the allocation of conservation areas may be constrained [2]. Caves containing rare troglobitic species, for instance, are always defined as maximal relevance caves, which must be protected along with a buffer area of 250m [8]. On the other hand, can be impacted if appropriate compensation offsets are provided (i.e. preserving two similar caves)

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