Advances in Serpentine Geoecology: A Retrospective

Abstract

Serpentine loosely refers to a broad group of minerals associated with the weathering of ultramafic (high iron and magnesium-rich) rocks found along continental margins and orogenic belts. Soils associated with such rocks often differ from more widespread soils, being less fertile and having high concentrations of some heavy metals. The unique geochemistry of serpentine soils generates habitats worldwide that are biologically unique, providing model settings for research on how geology and soils can shape the biotic world around us. Serpentine outcrops worldwide are known to harbor high rates of plant endemism (Brooks 1987, Kruckeberg 2002). For example, of the 1410 plant species endemic to California, 176 (12.5%) are restricted to serpentine (Safford et al. 2005), a substrate covering less than 1.5% of the state. This number is remarkably high given only 669 taxa are associated with serpentine soils in California. Thus, it is no surprise that serpentine floras are well-studied in California and other parts of western North America (Alexander et al. 2007, Harrison and Viers 2007), not only for their taxonomic value but also for their usefulness in testing ecological and evolutionary scenarios. Additional examples include the tropical islands of New Caledonia and Cuba, which also provide remarkable cases of serpentine endemism (Boyd et al. 2004, Brooks 1987, Kruckeberg 2002). In New Caledonia, 3178 taxa, approximately half the native fl ora, are endemic to serpentine soils (Jaffré 1992). In Cuba, 920 species, approximately one-third of the taxa endemic to Cuba, are found solely on serpentine soils (Borhidi 1992). Similar restrictions and notable floristic associations are also found in serpentine areas of the Mediterranean,

A global forum on ultramafic ecosystems: from ultramafic ecology to rehabilitation of degraded environments

“…Their scientific expertise ranges from soil science to evolutionary ecology and applied agronomy. Each conference was held in an ultramafic region with outstanding biodiversity: California in 1991 (Baker et al 1992), New Caledonia in 1995(Jaffre´et al 1997, Mpumalanga (South Africa) in 1999 (Balkwill 2001), Cuba in 2003 (Boyd et al 2004), Tuscany (Italy) in 2006 (Chiarucci and Baker 2007), Maine and eastern Canada in 2008 (Rajakaruna and Boyd 2009), Tras-o´s-Montes (Portugal) in 2011 (with a number of articles that appeared in Plant Ecology and Diversity) and Sabah (Malaysia) in 2014 (van der Ent et al 2015b).…”

Elemental composition of plants from the serpentine soil of Sugashima Island, Japan

“…In contrast, exchangeable Ni concentrations were low and ranged from 1.81 to 11.5 mg kg À1 . It is typical for serpentine soils (Brooks 1987;Roberts and Proctor 1992;Brady et al 2005;Rajakaruna and Boyd 2009; Harrison and Rajakaruna 2011), and soils from Sugashima Island, to contain high concentrations of Cr and Co. When compared with 'normal' soils (Asami 2001), concentrations of Ni, Cr and Co were 116, 62.8 and 45.8 times higher in the Sugashima Island soils, respectively.…”

“…High Ni toxicity, low Ca : Mg quotient and low nitrogen (N) and phosphorus (P) nutritional status influence the ecology of plants growing on serpentine soils (Brooks 1987;Roberts and Proctor 1992;Brady et al 2005;Rajakaruna and Boyd 2009;Harrison and Rajakaruna 2011). In addition, the high pH of serpentine soils may bias the plant community composition towards the presence of alkalophilic plants and the absence of acidophilic plants.…”

Natural revegetation potential of Japanese wild thyme (Thymus quinquecostatus Celak.) on serpentine quarries

“…However, the quantity available is small and it is difficult to keep it on the steep slopes once it has been returned. Furthermore, several characteristics of serpentine soil, such as high pH, aridity, low Ca:Mg quotient, and low nitrogen (N) and phosphorus (P) levels, also inhibit plant growth (Proctor and Woodell 1975;Brooks 1987;Kruckeberg 1992;Brady et al 2005;Rajakaruna and Boyd 2009;Safford and Mallek 2011). It is important to find candidate plants that are not only native to the serpentine area of Sugashima Island but also are adapted to the poor rocky soil, with high growth rates and reproductive output.…”