Phytoindication as a Unique Ecological Tool for Assessing the Response of Biotic Systems to Environmental Factors

Phytoindication represents a long-established ecological approach; however, its conceptual basis remains contested, particularly concerning whether it is merely a surrogate for measuring environmental factors or a distinct method for assessing biotic system responses. In this study, we analysed vegetation communities of the sandy terrace in the Dnipro–Oril Nature Reserve (Ukraine) using ecological indicator values, naturalness, and hemeroby indices. A dataset of 1,079 relevés was collected and classified into 24 associations, and multivariate analyses (MANOVA, CCA, partial CCA) were applied. We found that indicator values were not independent but strongly intercorrelated, reflecting integrated biotic responses rather than methodological artefacts. Two major patterns of variability were identified: the first described the coordinated dynamics of natural factors (soil moisture and nutrient availability positively correlated with decreasing light, temperature, continentality, and soil reaction), while the second reflected anthropogenic influence expressed in the hemeroby–naturalness gradient. These synthetic gradients explained vegetation structure at both meso- and fine-scale levels, with plant associations capturing the explanatory power of natural factors, whereas anthropogenic drivers remained less specific. Our findings support the view that phytoindication is not a simplified or less precise substitute for instrumental measurements but a unique ecological tool for assessing the integrated response of ecosystems to environmental drivers.