Submitted to: Restoration Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/9/2003
Publication Date: 3/1/2004
Citation: Whiting, S.N., Reeves, R.D., Richards, D., Johnson, M.S., Cooke, J.A., Malaisse, F., Paton, A., Smith, J.A., Angle, J.S., Chaney, R.L. 2004. Research priorities for conservation of metallophyte biodiversity and its sustainable uses in ecological restoration and site remediation. Restoration Ecology. 12(1):106-116. Interpretive Summary: Plants have evolved on metal rich soils and may have very high metal resistance by excluding metals at the root, or accumulate very high levels of metals by compartmentation of metals in vacuoles. Such highly metal tolerant plants offer tools to remediate contaminated soils, either by use of metal-resistant plants to stop soil erosion, or metal accumulator plants to phytoextract metals from the soil. In either case, it will be important to conserve these wild plants and improve our understanding of the mechanisms they use to resist or hyperaccumulate the metals. This paper is the outcome of a Workshop on Metallophytes held at the Kew Royal Botanic Garden in 2002 to summarize knowledge of these plants, including how they can be used in environmental protection and how they can be conserved. Plants with the ability to hyperaccumulate Ni, Co, Zn, Cd, As, Mn, and Se to levels which could give significant annual removal for phytoextraction are known. One species, Alyssum murale, has been developed to become the first commercial technology of phytoextraction, for Ni from contaminated or mineralized soils. Important research needs for understanding how plants resist or hyperaccumulate metals were listed. One of the important institutional aspects of these plants is the likelihood that mining companies will make useful plants extinct before they recognize the value of these plants for revegetation of their mine sites. Advice for preservation of local diverse metallophytes is provided to the mining industry. Some of these local metallophytes may have wide adaptation and may be developed in cultivars for conservation plantings at contaminated soils.
Technical Abstract: Plants that have evolved to survive on metal-rich soils ' metallophytes ' have key values that must drive research of their unique properties and ultimately their conservation. The ability of metallophytes to tolerate extreme metal concentrations commends them for revegetation of mines and metal-contaminated sites. Metallophytes can also be exploited in environmental technologies, e.g., phytostabilization, phytoremediation and phytomining. Actions towards conserving metallophyte species are imperative, as metallophytes are increasingly under threat of extinction from mining activity. Whilst many hundreds of papers describe both the biology and applications of metallophytes, few have investigated the urgent need to conserve these unique species. This paper identifies the current state of metallophyte research, and advocates future research needs for the conservation of metallophyte biodiversity and the sustainable uses of metallophyte species in restoration ecology, contaminated site remediation and nascent phytotechnologies. Six fundamental questions are addressed: 1) Is enough known about the global status of metallophytes to ensure their conservation? 2) Are metallophytes threatened by the activities of the minerals industry, and can their potential for the ecological restoration of disturbed land be realized? 3) What problems exist in gaining prior informed consent to access metallophyte genetic resources and how can the benefits arising from their uses be equitably shared? 4) What potential do metallophytes offer as a resource base for phytotechnologies? 5) Can genetic modification be used to 'design' metallophytes to use in the remediation of contaminated land? 6) Does the prospect of using metallophytes in site remediation and restoration raise ethical issues?