Functional traits of a broad-niched metallophyte along a toxicity gradient: disentangling intra and inter-population variation

Abstract

A B S T R A C TStudies on the relative contribution of inter-and intra-population trait variations in broad-niched species along edaphic gradients are still scarce. Here, we explore the variation of eight traits in five populations of Cyanotis longifolia, a broad-niched metallophyte thriving on very broad gradients of soil copper concentration in Central Africa. Variation at species level was decomposed into covariation with copper, variation among sites, and residual variation. The proportion of the variance explained by the site and by the local copper gradient in each site ranged from 10 to 32% and between 5 and 51% respectively, depending on trait. At the species level, specific leaf area decreased and leaf Cu and Co concentrations increased with increasing soil Cu concentration. Surprisingly, traits related to plant size show a quadratic response with higher values on both high and low soil Cu concentrations. This could be accounted for by population-specific patterns of covariation with soil copper. Population specific traits responses were found, with some populations exhibiting no significant response while the others sometimes show opposing variation patterns. The reasons for such idiosyncratic patterns are discussed in terms of interactions with other soil factors influencing Cu availability and toxicity. In further studies on trait variation along toxicity gradients, we recommend to investigate the small scale edaphic variability and to measure traits at the population level to capture the diversity of functional responses. contents or functional traits values (Lefebvre, 1974;Lange et al., 2017b;Stein et al., 2017;Frérot et al., 2018). Although metallophytes tolerance

Geochemistry of Terrestrial Plants in the Central African Copperbelt: Implications for Sediment Hosted Copper-Cobalt Exploration

“…Biologically essential elements (P, Ca, K, Mg, Na, S, Cu, Fe, Mo, Se, and Zn) are selectively taken up by vegetation. Beneficial and non-essential elements including those that are potentially toxic are also taken up and may closely reflect the composition of the soil and regolith [14,[100][101][102]. Cu is an essential plant micronutrient forming part of the protein structure for a range of enzymes that drive electron transport and redox reactions in plant organelles, including mitochondria, chloroplasts, cell walls and the cytoplasm of plant cells [83,103].…”

“…Aeolanthus biformifolius 3920 2820 [27] Annona senegalensis 2889 2650 [102] Ascolepis metallorum 1200 - [21] Buchnera henriquessi 3520 2435 [106] Bulbostylis mucronata 7783 2130 [13] Becium homblei 2051 - [105] Crotalaria cobalticola -3010 [6] Guternbergia cupricola 5095 2309 [107] Haumaniastrum Katangese 8356 2240 [84] Haumaniastrum robertii 8500 4000 [122] Haumaniastrum rosulatum 1089 - [19] Ipomoea alpina 12,300 - [27] Lupinus perennis 9322 2300 [101] Rendlia cupricola 1560 - [65] Parinari curatellifolia [102] Experimental work has supplemented some of the field ecological studies in which two-month-old plants collected from seeds were exposed to soluble Cu and Co salts mixed with soil and used in simulating natural conditions [27]. The results of these experiments suggest that H. robertii may be tolerant to soil Cu and Co concentrations of up to 8500 mg•Kg −1 and 4000 mg•Kg −1 , respectively [19].…”