Spatial structure of the vegetation cover of the Abrau Peninsula (on the example of the Vodopadnaya Shchel)

Abstract

The uniqueness of the Abrau Peninsula (Fig. 1) is determined by a high level of floristic and phytocoenotic diversity and the relict nature of the vegetation cover. Сomplex spatial organization of the vegetation cover is reviled for this mountain territory (Sus­lova, Petrushina, 2007; Ogureeva et al., 2020). It is associated with heterogeneity of ecotopes. In this paper, a cartographic method has been tested to assess the vegetation cover of a mountainous territory through the identification of its spatial structure. Based on the coupled analysis of field data (geobotanical descriptions) and Earth remote sensing materials (multispectral satellite images, digital terrain model) using the classification of spectral features of communities by the maximum likelihood method using etalons and discriminant analysis, a cartographic model of a key area of the Vodopadnaya Shchel valley was obtained (Fig. 3). It reflects the diversity of basic vegetation formations and types of vegetation and the heterogeneous structures formed by their plant communities. The key factors of vegetation cover formation and its connection with the landscape structure of the territory were determined based on the spectral brightness variables of the images and relief features (Kozlov et al., 2008; Rocchini et al., 2013). The calculated relative diversity indices (Shannon and Simpson indices) made it possible to quantify the main factors determining the spatial structure of the vegetation cover of the Abrau Peninsula. The created large-scale (S. 1 : 50 000) inventory vegetation map of the Vodopadnaya Shchel reflects the actual vegetation cover, represented by a diversity of vegetation communities, belonging to hemixerophytic sub-Mediterranean and mesophytic nemoral formations (Fig. 6). The change of background communities along the high-altitude spectrum determines the allocation of two belts. The lower belt of hemixerophytic forests and woodlands is located at altitudes of 0–150 (200) m a. s. l. It is characterized by the development of pistachio-juniper (Juniperus excelsa, Pistacia mutica) forests and woodlands, oak (Quercus pubescens) forests, as well as serial vegetation with shrub and dwarf semi-shrub-herb communities. This belt is characterized by a high level of floristic and phytocoenotic diversity and a complex spatial structure associated with the contrast of ecotopes. The belt of mesophytic broad-leaved forests is located at altitudes of 150 (200)–450 m a. s. l. It is formed by pine-oak (Quercus petraea, Pinus kochiana) and polydominant broad-leaved (Carpinus betulus, Tilia begoniifolia, Acer campestre) forests. The spatial structure of the vegetation cover is formed under the influence of the altitudinal gradient and, within the belts – a variety of ecotopic factors under the conditions of seismic-gravity processes (Petrushina, Merekalova, 2017). There is a gradual transition from one belt to another, as a result of which the position of the boundaries of the altitudinal belts varies depending on the type of morphostructures, the steepness and exposure of the slopes. Spatial patterns in the distribution of phytocoenotic diversity within and between altitudinal belts are associated with a complex of conditions, the gradients of which are expressed between different landforms and in connection with changes in morphometric characteristics, as well as the dynamic status of communities. The closest connections were found with the indicators of absolute height, the exposure of slopes, as well as in accordance with the catenary structure of the territory. The closest connections were found with absolute altitude, slope exposure, as well as with different geochemical positions of catena. Cartographic analysis revealed the main gradients of the spatial structure of the vegetation cover of the Abrau Peninsula. They are associated with an integral altitudinal gradient, under the influence of which an increased variety of sub-Mediterranean formations of the lower belt is formed. The increase in moisture supply determines the tendency to increase the diversity from eluvial to accumulative positions of catena in both altitudinal belts (Table 4). The revealed spatial patterns are important in understanding the formation of orobiomes presented on the map “Biomes of Russia” (Biomy …, 2018) and the mountain ecosystems formed by them within the altitudinal belts of vegetation.