FEATURES OF LIFE FORMS OF PLANTS OF THE LOWER LAYER OF FOREST ECOSYSTEMS

Abstract

The problem of classification of life forms and their evolutionary relationships has attracted the attention of many researchers. The term “life form” was introduced in the 80-ies of the 19th century by famous Danish botanist Eugen Warming, one of the founders of plant ecology. The classification of life forms proposed by the great Danish botanist Christen C. Raunkiær received the greatest popularity not only among ecologists. The scientist distinguished from a set of features of life forms one extremely important one that characterizes plant adaptation to survive the unfavorable season, be it cold or dry. This feature is position of reproductive bud on the plant as to the level of substrate and snow cover. Raunkiær linked it with the protection of buds in the adverse season.

According to Christen C. Raunkiær, life forms of plants can be divided into five main types: phanerophytes (Ph), chamephytes (Ch), hemicryptophytes (PC), cryptophytes (K) and therophyte (Th) (from the Greek “phaneros” – open, manifest (“come to light”); “chame” – low, grounded; “hemi” – semi; “cryptos” – hidden; “theros” – summer; “phyton” – plant).

M. Lavrenko (1964) proposed the concept of ecobiomorpha for integrated assessment of plant adaptation to the environment. Ecobiomorpha is a set of species similar in morphological, biological and ecological-physiological characteristics, and their habitats.

We studied groups of species of lower layers of forest ecosystems in the north-east of Ukraine. On the basis of personal geobotanical descriptions in the forests of Novgorod-Siversky Polissya and literature data, 32 species (Actaeaspicata L., L. Aegopodiumpodagraria, Ajugareptans L., L. Asarumeuropaeum, etc.) were selected as model species of a group of vegetative-mobile plants of lower layers of forest ecosystems (as characteristic and the most common ones for the major plant communities, but not typical for the forests of the region) .

C. Raunkiær’s system of life forms is the most useful and informative one for the forests of moderate climate. Groups of species of lower layer of forests in the north-east of Ukraine are characterized by predominance of hemicryptophytes, normally comprising over 60% of plant species. Long-rhizomatous, short-rhizomatous, bunch-rhizomatous, bulbous and tuberous forms are registered in the lower layer of these forests in order of decreasing representation.

The composition of life forms of grass and subshrub layer of forest ecosystems demonstrates the high adaptability of these plant species to growing conditions. These species have mainly the overwintering parts, which are deep in the soil or on the soil surface and covered with a layer of leaf litter.

An important adaptive ability of plants of lower layers of forests is change of life form and morphological organization during successive or anthropogenic transformation of forest ecosystems.