The influence of microclimatic differences in the city of Arzamas on phenological processes
Authors:   National Research State University of Nizhny Novgorod named after N. I. Lobachevsky, S. Lyubov Mikhail , I. Nedoseko Olga ,   National Research State University of Nizhny Novgorod named after N. I. Lobachevsky, A. Shemanaev Valery ,   National Research State University of Nizhny Novgorod named after N. I. Lobachevsky, I. Miticheva Tatyana ,   National Research State University of Nizhny Novgorod named after N. I. Lobachevsky
Published: February 2025

Background. Phenological processes in living and inanimate nature develop differently depending on location, relief features, microclimate and other factors. Such dynamics become especially noticeable in a city with different ecological and geographical conditions. Identification of differences in the dynamics of seasonal processes and phenomena allows for rational implementation of city improvement works, its landscaping, etc. At the same time, this information is very useful for the population living in specific environmental conditions of the city. It should be noted that there are relatively few studies in the scientific literature on the topic of the influence of the urban environment and urban microclimate on the dynamics of phenological processes in the context of a rapidly changing climate in the 21st century. The issue of the influence of hypsometric forms of urban relief on the timing of the onset of certain phenological phenomena remains insufficiently studied. The purpose of the work is to identify differences in the dynamics of phenological processes in the areas of the city of Arzamas, Nizhny Novgorod region with heterogeneous microclimatic conditions. Materials and methods. The main seasonal phenomena and key phenoobjects of living and inanimate nature were selected for the analysis by seasons of the year. For example, the dates of the first snow cover falling and forming, the transition of the average daily air temperature through 0 °C, the beginning of active destruction of the snow cover, the beginning of flowering of some primrose plants (coltsfoot), the appearance of leaves on the birch, the beginning of flowering of common bird cherry, common lilac, May rose, small-leaved linden, the be ginning of yellowing of foliage, etc. were recorded. At the same time, the dates of the onset of phenological phenomena in the lower and upper parts of the city of Arzamas, which have different microclimates, were recorded. Results. Analysis of observations shows that the difference in altitude between the upper and lower parts of the city of 40–60 m creates, under conditions of an anticyclonic state of the atmosphere, a temperature inversion of up to 10 °C or more during the dark hours of the day. This temperature contrast creates noticeable differences in the average daily air temperature in the upper and lower parts of the city. At the same time, the lower part of the city turns out to be somewhat colder than the upper one. These differences are most clearly evident in the spring, when the vegetation cover is not yet sufficiently developed and the state of the atmosphere is often anticyclonic. This in turn causes some delay in vegetation processes (beginning of flowering, appearance of foliage, etc.) in plants in the lower part of the city, on average by 2–3 days. In the summer and autumn periods, microclimatic differences in the upper and lower parts of the city are less noticeable, and, accordingly, the differences in the onset of dates of phenological phenomena are not so great and amount to an average of 1–2 days. Conclusions. The obtained observation results show a significant contrast in the dynamics of phenological processes in the lower and upperparts of the city. Moreover, such noticeable differences can be traced both in the dynamics of living nature and in the dynamics of inanimate nature.