Ultramafic vegetation and soils in the circumboreal region of the Northern Hemisphere

The paper summarizes literature on climate, soil chemistry, vegetation and metal accumulation by plants found on ultramafic substrata in the circumboreal zone (sensu Takhtajan, Floristic regions of the world, 1986) of the Northern Hemisphere. We present a list of 50 endemic species and 18 ecotypes obligate to ultramafic soils from the circumboreal region of Holarctic, as well as 30 and 2 species of Ni and Zn hyperaccumulators, respectively. The number of both endemics and hyperaccumulators are markedly lower compared to that of the Mediterranean and tropical regions. The diversity of plant communities on ultramafics soils of the circumboral region is also described. The underlying causes for the differences of ultramafic flora between arctic, cold, cool temperate and Mediterranean and tropical regions are also discussed. © 2018, The Ecological Society of Japan

Nickel localization on tissues of hyperaccumulator species of Phyllanthus L. (Euphorbiaceae) from ultramafic areas of Cuba

20 pages.-- ISI Article Identifier: 000244284900007.Two species of perennial Phyllanthus (Euphorbiaceae) (Phyllanthus orbicularis and Phyllanthus discolor, both endemic to ultramafic areas of Cuba, and their natural hybrid, Phyllanthus xpallidus) were selected for metal localization microanalysis. Different plant tissues were analyzed by X-ray fluorescence, inductively coupled plasma—atomic emission spectroscopy, and scanning electron microscopy coupled with an energy-dispersive X-ray probe. All of the studied taxa are nickel (Ni) hyperaccumulators and significant concentrations of this element were found in different leaf and stem tissues. The highest Ni content was found in the laticifer tubes, whereas leaf epidermis Ni content resulted to be much more relevant in terms of total metal storage. Calcium and magnesium were found more evenly distributed in leaf and stem tissues.Peer reviewe

Global Distribution and Ecology of Hyperaccumulator Plants

International audienceA large body of analytical data is available on the inorganic composition of many thousands of plant species, for which typical concentration ranges have been tabulated for major, minor, and trace elements. These elements include those that have been shown essential for plant growth, as well as others that lack this status, at least universally. Metalliferous soils, having abnormally high concentrations of some of the elements that are generally present only at minor (e.g. 200–2000 μg g−1) or trace (e.g. 0.1–200 μg g−1) levels, have attracted increasing attention during the last 50 years. The effects vary widely, depending on the species, the relevant elements, and soil characteristics that collectively influence the availability of metals to plants. Some of these soils are toxic to all or most higher plants. Others have hosted the development of specialized plant communities consisting of a restricted and locally characteristic range of metal-tolerant species. These typically show a slightly elevated concentration of the elements with which the soil is enriched, but in places a species may exhibit extreme accumulation of one or more of these elements, to a concentration level that can be hundreds or even thousands of times greater than that usually found in plants on the most common soils. These plants, now widely referred to as hyperaccumulators, are a remarkable resource for many types of fundamental scientific investigation (plant systematics, ecophysiology, biochemistry, genetics and molecular biology) and for applications such as phytoremediation and agromining. Systematic analysis of herbarium specimens by X-ray Fluorescence, combined with auxiliary collection data, can provide insights into phylogenetic patterns of hyperaccumulation, and has the potential to complement and add insights to biogeographical and phylogenetic studies