Complex Of Abiotic Factors Research Articles

Flora and syntaxonomy of communities including <i>Juniperus oblonga</i> M. Bieb. on the Gunib Plateau

Aim. To identify and describe communities which include Juniperus oblonga on the Gunib Plateau. To conduct a taxonomic, geographical, biomorphological analysis of the flora of these communities.Material and Methods. The research was carried out by the method of the laying of trial plots. 15 geobotanical descriptions were undertaken. Office data processing was carried out using tabular ecological‐phytocenotic analysis. Analysis of the flora of the communities was carried out according to generally accepted methods of floristic research.Results. The flora of the juniper woodlands of the Gunib Plateau is represented by 185 species from 124 genera and 41 families. According to the results of geographical analysis, 19 geoelements were identified from 4 geotypes, of which the species of the boreal group (53.8%) of the Caucasian geoelement (31.9%) are the most represented. There are present rare and disappearing (2.7%), endemic (28.1%) and relict species (14.1%). An ecological‐phytocenotic classification of communities with the participation of Juniperus oblonga on the Gunib Plateau was developed and 4 associations, 5 subassociations and 5 variants were identified. A prodromus was compiled.Conclusion. Sparse juniper forests are one of the main types of vegetation of the Gunib Plateau, constituting a third of the flora of the plateau with a high degree of uniqueness and a complex of abiotic factors that change along the altitudinal gradient, microrelief and slope exposures, which are decisive when dominants change in communities of sparse juniper forests.

Bioenvironmental characteristics of Robinia pseudoacacia steppe plantations in dependence to changes in some climatic factors

Сlimatic factors play the most important role in the plant associations formation. Sunlight is one of the leading factors that determine the appearance of a particular community and very often plays the limiting factor role. In the conditions of the Steppe Dnipro Region, its limiting role can be expressed only in its excess. The great majority of autochthonous steppe flora plant species has strongly pronounced adaptations to excessive solar insolation. With the development of forest biogeocenology and steppe forestry, more and more attention is paid to the issues of forest climatology. It is shown that climatic factors have an imperative effect on the formation of soils, plant associations, fauna and ecosystems in general. Artificial plantations consisting of fast-growing hardwoods, such as Robinia pseudoacacia, have been studied. The complex of abiotic factors in robinia plantations and in open areas has its own characteristics. The processes of reflection, transformation and accumulation of solar energy in tree plantations have a slightly different character than in forest-free areas. In the Dnipropetrovsk region, the populations of Robinia pseudoacacia are represented mainly by young plants that have already entered the phase of active fruiting. No plants older than 100 years were found in the populations. Thus, the price spectrum of the age composition of the population of Robinia pseudoacacia in the Dnipropetrovsk region has a pronounced left-sided character, ie shifted towards young individuals that are actively fruiting. This indicates that the processes of expansion of Robinia pseudoacacia to natural biogeocenoses will be actively continued. Despite the fact that this breed has a number of positive qualities (excellent medonis, root mycorrhiza with azotobacter, high gas resistance, etc.), the processes of uncontrolled active settlement of this species is a matter of serious concern. This breed is capable of rapid spread and disruption of successional processes occurring in the area. In the conditions of the forecasted climate changes towards temperature increase and precipitation decrease this breed receives more and more advantages.

Where a springhead becomes a springbrook a regional zonation of springs

Springs are important freshwater habitats that provide specific abiotic conditions for many species. These conditions may change very rapidly downstream. Limnologists tend to treat spring sources and their adjacent springbrooks as a unity because of the lack of clear criteria to separate these sections. In this study, we investigated the longitudinal distribution of macroinvertebrate assemblages in ten undisturbed springs in north-western Switzerland at three different distances from the source. Using non-metric multidimensional scaling and analysis of similarities, we detected significant differences between the macroinvertebrate assemblages of the investigated sections in all spring ecosystems, even over short distances. These results stress the importance of distinguishing between the sequential habitats in this upper region of headwaters. Although a complex of abiotic factors is responsible for the distribution of macroinvertebrates, we consider temperature to be of special importance. Based on our faunistic data, we propose that the rheocrene-like springs in the Jura Mountains consist of two sections: the springhead and the springbrook, with the springhead consisting of the source and the upper part of the adjacent downstream section. In accordance with literature and our faunistic and temperature data, we place the beginning of the springbrook at approximately 5 m from the springhead. With this distinction, we justify that springheads and springbrooks are unique, discrete ecosystems, and as such must be considered in conservation legislation.