Habitat conditions of lignite mine waste dumps and the development of spontaneously colonizing vascular plant flora

Abstract How substrate conditions relate to spontaneous plant colonisation of lignite waste dumps remains poorly resolved in seasonally dry environments. We compared vascular plant records with mineralogical and physicochemical measurements from two lignite waste dumps near Lenger, southern Kazakhstan. The anthracite-like waste (A) was strongly acidic at its bare surface (pH 2.19–3.62) and had high electrical conductivity, whereas vegetated areas at the dump base were near neutral; at the dump margin, where Dodartia orientalis was found sporadically. Vegetation was sparse and patchy. Asteraceae and Poaceae dominated the herbaceous component, while Capparis spinosa formed sparse shrub patches on waste B; no trees were recorded. Centaurea virgata subsp. squarrosa (= Centaurea pseudosquarrosa ) Agropyron cristatum and Elymus repens were among the most abundant taxa. Waste samples A, taken from beneath the plants, contained more silt than adjacent bare samples, but this pattern was not universal. Paired microsite contrasts varied in direction; these descriptive observations do not establish a general plant–substrate relationship or a temporal succession rate.