Abstract
QuestionsEffects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response?LocationEastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate.MethodsWe analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale).ResultsThe soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.ConclusionUsing annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability) and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically observed as a consequence of strong environmental filtering, as for instance on sites affected by industrial activities.
Highlights
Understanding of species responses to well-defined environmental gradients is fundamental to developing and testing ecological theory, improving methods of community analysis and use of indicator species in environmental assessments, and predicting the impacts of global change on vegetation [1]
The differentiation of weed vegetation along the soil gradient was achieved by a remarkable shift in dominance relations, and not by a prominent presence/absence turnover
Of the total of 84 weed species recorded in the survey, 63% were present on both relatively undamaged calcareous soils of the Zone 1 and on the most severely altered acidic soils where substantial reduction of crop growth occurs in Zone 4 (Table S2)
Summary
Understanding of species responses to well-defined environmental gradients is fundamental to developing and testing ecological theory, improving methods of community analysis and use of indicator species in environmental assessments, and predicting the impacts of global change on vegetation [1]. Community ecology has had little success in revealing general ecological principles, in particular in explaining why communities change in a systematic way across space; this is bringing about a shift of research focus towards explicit environmental gradients and ecophysiological plant traits [4]. A remarkable feature of spontaneous vegetation developing on post-mining land is the occurrence of new, surprising combinations of species that bear little resemblance to the assemblages on non-affected soils [11], [12]. This has broadly been recognized in the emerging concept of ‘‘novel ecosystems’’ which arise as a consequence of anthropogenic degradation [13]-
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