Vulnerability to Copper Smelter Emissions in Species of the Herb–Dwarf Shrub Layer: Role of Differences in the Type of Diaspore Dispersal

Abstract

The type of diaspore dispersal may have a significant effect on the vulnerability of herbaceous plants to anthropogenic transformation of ecosystems. However, there is still no unified opinion on the relationship between the type of diaspore dispersal and the processes of extinction and colonization. Here, descriptions of vegetation performed in the zone of impact from the Middle Ural Copper Smelter in the periods of high and low emission levels (1995–1998 and 2014–2016, respectively) have been analyzed to test two hypotheses: (1) the type of diaspore dispersal has an effect on plant vulnerability, with the species whose diaspores are dispersed farther being less vulnerable to habitat transformation; and (2) irrespective of the type of dispersal, recolonization is less intense under high than under low pollution levels. It has been found that the species richness of all plant groups highly varies in space: it decreases sharply in the zone of heavy toxic loads, but localities with high species richness occur even under conditions of heavy pollution. With the increasing pollution level, the species diversity within plant groups on a mesoscale (hundreds of meters) decreases more strongly than that on a macroscale (kilometers). Species with different types of diaspore dispersal differ from each other both in sensitivity to pollution and in the capacity for recolonization after reduction of emissions, but the relationship between vulnerability and the distance of diaspore dispersal is ambiguous. High sensitivity to pollution and low recolonization capacity have been revealed in species characterized by either the lowest (autochores) or the highest dispersal distance (epi- and endozoochores), with anemochores being the least vulnerable. The diversity of most groups in the zone of heavy pollution has remained low over the past 20 years; some positive shifts have occurred in myrmecochores and typical anemochores, with the dynamics of the latter being independent of pollution level.