Ecological aspects of meadow phytocenoses
Abstract
The article states that meadow phytocenoses are distinguished from others (forest, steppe, desert, water and others) by the dependence of the composition and structure (structure) of meadow communities on environmental conditions. At the same time, onions differ from agrophytocenoses on arable lands. On arable land, in the process of crop rotation every year (or with a break of one year in the chain of peren-nial grasses), the existence of phytocenosis is disturbed by the agricultural machinery used to cultivate the soil. Therefore, crops of grain or row crops are always available for the spread of weeds. In order to control their number, it is necessary to use an integrated system of plant protection, which includes agrotechnical measures, and biological and chemical methods of control. The meadow, unlike such agrophytocenosis, is closed to the spread of weeds, since there are competitive relationships between the plant populations that are part of it. It is substantiated that as a result of competition and differentiation of niches, the structure of the meadow phytocenosis is formed – the height difference of the aerial parts and the depth of the root systems. There are no clear layers of it above ground or below ground in meadow grass stands, but sometimes stable combinations of species are formed on the meadow, which are repeated like spots. Such spots are called micro groups, and the phenomenon itself is called mosaicism. However, mosaicism is not very common and is usually associated with the distribution of leguminous components, which have a stronger impact on the environment than other species. Leguminous grasses are known to enrich the soil with nitrogen as a result of the activity of nitrogen fixers symbiotically associated with them, and in favorable years they form many leaves, which can limit the growth of light-loving species. It was noted that the peculiarity of meadow phytocenoses is the correspondence of their composition and structure to the smallest changes in environmental conditions, which in forest phytocenoses will be leveled as a result of the strong influence of trees, and in arable land they are somewhat leveled by the system of soil cultivation, application of fertilizers and sowing. However, rapid spatial variability is only one of the many qualities of these plastic communities. Meadow phytocenoses can change over time quite quickly. At the same time, it is worth distinguishing 2 types of changes – reversible and irreversible. In the first case, changes in the composition of meadow phytocenosis are associated with seasonal changes, with fluctuations in weather conditions in different years, with the intensity of pasture use, outbreaks of the number of certain types of meadow grasses, or the spread of nematodes or pest insects on meadow grasses. In the second case, meadow communities change under the influence of anthropogenic factors (hay mowing or fertilization) or, on the contrary, self-restore after the cessation of the influence of a certain factor. It should be noted that usually 2 main variants of successions can be observed on meadow phytocenoses: caused by internal causes (autogenic) and external (allogenic). However, it should be noted that the main successions in meadows are allogenous, which are related to changes in environmental conditions or the mode of use. Most often, the root cause of these changes is the human factor. Autogenous changes are most often restorative in nature.
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