Mining in New Caledonia: environmental stakes and restoration opportunities

Abstract

New Caledonia is a widely recognised marine and terrestrial biodiversity hot spot. However, this unique environment is under increasing anthropogenic pressure. Major threats are related to land cover change and include fire, urban sprawling and mining. Resulting habitat loss and fragmentation end up in serious erosion of the local biodiversity. Mining is of particular concern due to its economic significance for the island. Open cast mines were exploited there since 1873, and scraping out soil to access ores wipes out flora. Resulting perturbations on water flows and dramatic soil erosion lead to metal-rich sediment transport downstream into rivers and the lagoon. Conflicting environmental and economic aspects of mining are discussed in this paper. However, mining practices are also improving, and where impacts are inescapable ecological restoration is now considered. Past and ongoing experiences in the restoration of New Caledonian terrestrial ecosystems are presented and discussed here. Economic use of the local floristic diversity could also promote conservation and restoration, while providing alternative incomes. In this regard, Ecocatalysis, an innovative approach to make use of metal hyperaccumulating plants, is of particular interest.

Biodiversity hotspots and Ocbil theory

“…New Caledonia is also well known for its relative abundance of ancient lineages and the persistence of a suite of palaeoendemics (Pillon 2012), providing support for the Ocbil hypothesis concerning increased rarity and endemism, although New Caledonia's endemism may also be due to its insular nature. Additionally, the vegetation is highly sensitive to soil removal (Losfeld et al 2015), which is another prediction of Ocbil theory (Hopper 2009). …”

“…New Caledonia is a global biodiversity hotspot facing extreme environmental degradation due to land cover change, fire, urban sprawl and mining (Wulff et al 2013;Losfeld et al 2015). Pillon (2012) suggested that 'because of the abundance of low fertility soils, New Caledonia may be considered to be an old, climatically buffered and infertile landscape (OCBIL; Hopper 2009), similar to the Cape and to south-west Australia, but its climatic stability remains to be proven.'…”

“…The vulnerability of Ocbil communities to topsoil removal is now evident in the campo rupestre (Le Stradic et al 2014a, b), New Caledonia (Losfeld et al 2015) and in metal-rich grasslands in Congo (Le Stradic et al 2016), as well as in the SWAFR. In campo rupestre, natural regeneration struggles to return even after decades following soil removal .…”

“…Because the geographic range of species is the most reliable predictor of extinction risk, it is clear why plants from Ocbils are increasingly joining the IUCN Red List as extinct (Martinelli and Moraes 2013). This fact indicates that restoration ecology deserves focused attention for the conservation of these endemic and threatened biotas, such as the Brazilian iron-rich canga in the Brazilian cerrado (Jacobi et al 2007), cobalt-rich grasslands in Congo (Faucon et al 2010), nickel-rich vegetation in New Caledonia (Wulff et al 2013, Losfeld et al 2015, and banded ironstone outcrops in the SWAFR (Gibson et al 2012). Moreover, granitic inselbergs interspaced throughout several Yodfels in biodiversity hotspots are under increasing rates of quarrying (Porembski and Barthlott 2000).…”

Dynamics of Suspended Sediments during a Dry Season and Their Consequences on Metal Transportation in a Coral Reef Lagoon Impacted by Mining Activities, New Caledonia

“…With about 85% endemism among terrestrial plants, 24 different species of mangroves among the 70 listed throughout the world, about 2800 species of molluscs and the second longest barrier reef in the world [10][11][12][13][14][15], New Caledonia's ecosystems and biodiversity are highly sensitive to anthropogenic activities (e.g., [16][17][18][19][20][21][22][23] for its lagoons). Since the beginning of mining in New Caledonia, more than 160 × 10 6 tonnes of ore have been extracted.…”