Options for the Relationship Between Height and Projective Coverage of Certain Species of Herbal Plants on Environmental Gradients and Visually Homogeneous Areas of Landscape

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Within any area of terrain (landscape), the height and projective cover of individual plant species usually vary signifi cantly. This may be due to both the heterogeneity of the abiotic environment (the presence of microareas with good and bad growing conditions) and other reasons, for example, the incompleteness of the invasion process or biotic interactions. It can be expected that in the fi rst case there should be a good correspondence between the values of these characteristics (autand synecological). In other cases, the connection between them may be different, poorly expressed or absent. During the 2023 fi eld season, we assessed the nature of the relationship between height and projective plant cover in 43 local populations of key plant species in the low- and high-mountain zones of the Western Caucasus. The results showed that in most populations described in areas with clearly defi ned environmental gradients and undisturbed vegetation, a close relationship of an exponential or logistic type is observed between them. On the contrary, in most populations of key species in visually homogeneous areas of synanthropic vegetation (old fallow lands, wastelands, etc.) it was absent or poorly expressed, which may indicate instability of their spatial structure and the presence of prerequisites for changes in the participation of species in the future. In addition, in the populations of the three species, we found a discrepancy between their autecological and synecological optima (the highest coverage was observed in sites with an average height of individuals); for another fi ve species – poor correspondence between height and cover at the boundaries of their distribution or area of dominance with relatively “soft” environmental conditions (low cover with signifi cant height of individuals) in contrast to the situation at the boundaries with harsh conditions (low cover and small size of individuals). The last observation supports the hypothesis about the different roles of abiotic and biotic factors in determining the boundaries of species in the most and least severe growing conditions.