Micro-spatial variation of soil metal pollution and plant recruitment near a copper smelter in Central Chile Rosanna Ginocchio a,b, *,Gasto´nCarvallo a , Ignacia Toro a , Elena Bustamante b , Yasna Silva b ,NancySepu´lveda b a Departamento de Ecologı´a, P. Universidad Cato ´lica de Chile, Casilla 114-D, Santiago, Chile b Centro de Investigaciones Mineras y Metalu ´rgicas,Av. Parque Antonio Rabat 6500, Vitacura, Santiago, Chile Received 18 February 2003; accepted 25 August 2003 ‘‘Capsule’’: Metal availability was different under shrub canopies than in open spaces. Abstract Soil chemical changes produced by metal smelters have mainly been studied on a large scale. In terms of plant survival, deter- mination of small scale variability may be more important because less toxic microhabitats may represent safe sites for successful recruitment and thus for plant survival. Three dominant microhabitats (open spaces and areas below the canopy of Sphaeralcea obtusiloba and Baccharis linearis shrubs)weredefinedinaheavilypollutedareanearacoppersmelterandcharacterisedintermsof microclimate, general soil chemistry, total and extractable metal concentrations in the soil profile (A 0 horizon, 0–5 and 15–20 cm depth), and seedling densities. Results indicated a strong variability in microclimate and soil chemistry not only in the soil profile but also among microhabitats. Air/soil temperatures, radiation and wind speed were much lower under the canopy of shrubs, particularly during the plant growth season. Soil acidification was detected on top layers (0–5 cm depth) of all microhabitats while higher concentrations of N, Cu and Cd were detected on litter and top soil layers below shrubs when compared to open spaces; however, high organic matter content below shrubs decreased bioavailability of metals. Plant recruitment was concentrated under shrub canopies; this may be explained as a result of the nursery effect exerted by shrubs in terms of providing a more favourable microclimate, along with better soil conditions in terms of macronutrients and metal bioavailability. # 2003 Elsevier Ltd. All rights reserved. Keywords: Spatial heterogeneity; Copper pollution; Avoidance mechanisms; Environmental heterogeneity; Abiotic factors 1. Introduction Soil chemical changes produced by metal smelters have mainly been studied on a macro-scale (e.g. kilo- metres, hundred metres), and thus mean metal values for an area have been more representative parameters than any measure of variability inside the area. How- ever, from the plant point of view, small-scale varia- bility in soil chemistry (e.g. metres, centimetres) in highly polluted areas may also be important; less toxic microhabitats may represent safe sites for successful recruitment and establishment of non-metal tolerant or sensitive plant species. Although metal tolerant plants havebeenfrequentlyconsideredthedominantspeciesat metal smelter polluted sites (e.g. Cox and Hutchinson, 1980; Rauser & Winterhalder, 1985; Lolkema et al., 1986; Winterhalder, 1995), sensitive species have also been found in heavily polluted areas near a copper smelter in central Chile (Ginocchio, 1999) where mean total copper concentrations may reach up to 1500 mg kg 1 (Gonza´lez & Ite, 1992; Pozo, 1993). Climatic and edaphic factors can show great small- scale heterogeneity in many habitats, thus providing contrasting environments for plants in terms of resource supply (Skousen et al., 1990; Marshall and Price, 1997). Metalsmelterpollutedsitesarenoexception;greatvaria- bilityinmetallevelsmaybefoundbetweenmicrohabitats and within the soil profile. However, there are few reported studies where the small-scale heterogeneity of edaphic factors in metal rich areas has been carefully 0269-7491/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2003.08.020 Environmental Pollution 127 (2004) 343–352 www.elsevier.com/locate/envpol * Corresponding author. Fax: +56-2-364 3570. E-mail address: rginocc@cimm.cl (R. Ginocchio).