Ecological-coenotic strategy of floral elements of park phytocoenoses

The process of natural development of park phytocoenoses mainly depends on ecological-coenotic strategy of their components and specifics of their space and allopatric interaction. Floral specifics of park phytocoenoses are stipulated by existance of populations of autochthonous forest, meadow and stocking plants of different ecological-coenotic strategy. According to Mr. L.G. Ramenskiy (1971) there are three types of ecological-coenotic strategy of plants (phytocoenotypes) – dominant (plants which are edificators of plant groups), tolerant (plants which are adopted to life under condition of constant phytocoenotic stress, for example, in shadow) and exploratory (plants with low compatibility, but with property of quick seizing the emptied territories).

The research of park phytocoenoses of different age allowed to reveal peculiarities of ecological-coenotic  strategy for 90 wood and brush species. The specially elaborated five-point system of evaluation has been used. (Table 2).

Table 2

Evaluation scale of dominant, tolerant and exploratory properties of units, unit groups (coeno-populations) of wood and brush species in park plantations  

Evalua -tion in points	Ecological-coenotic property
	Dominant	Tolerant	Exploratory
5 – very high	Trees of the first size with wide tight crown which are distinguished by their quick growth. Win in competitive fight for life resources	Can be grown under tight canopy of plantations and create tangle	Widely propagated by vegetative and seed, capable to seize free space completely during 1-2 years
4 – high	Trees of the first size with narrow tightness  or wide open-work crown. Essentially  influence forming of subordinated storeys  of flora.	Can be grown under tight canopy of plantations, but do not create tangle	Widely propagated by generative way, capable to seize free space completely during 2-5 years
3 – average	Trees  of the second and third size, shade resistant. Their wide open-work crown permit other tree development which in the course of time can achieve  the first storeys.	Can be grown under tight canopy  of plantations for long time (10-20 years) . Growth is rather slow, but vital capacity is high	Periodically form new growth    which can gradually seize free space
2 – low	Trees  of the third size or high brushes which never form canopy, but essentially influence development of brush and grass storeys.	Can be grown under tight canopy of plantations for some time (5-10 years) . Growth is rather slow and vital capacity is low	New growth  develops well under conditions of free space, create numerous additions to groups of explerents
1 – very low	Single trees  of the third size or brushes which incidentally influence development of brush and grass storeys	Can be grown under tight canopy  of plantations for short time (1-3 years) . Vital capacity is low	Existing new growth  is  better developed under conditions  of free space, but do not seize free territories

The tree species which are remarkable for maximum dominance and which  at the same time are characterized by high tolerance and exploratory proprerties include Acer pseudoplatanus, Acer platanoides, Picea abies (L.) Karst., Quercus borealis, Fagus sylvatica.  Other strongly dominant plants reveal less tolerance and exploratory properties. They are: Aesculus hippocastanum L., Alnus glutinosa (L.) Gaertn. Juglans regia L., Populus tremula, Fraxinus excelsior, Fraxinus lanceolata, Fraxinus pensylvanica Marsh., Betula pendula Roth., Quercus robur, Populus nigra L. They are capable to reproduce by seed natural renovation, but they are not numerous, and under condition of under-canopy shading they are considerably oppressed and often rot. Such species as Acer negundo, Acer saccharinum, Alnus incana (L.) Moench, Abies concolor (Gord.) Hildebr., Salix alba (L.). yield above mentioned kinds by aggressive capability. But they are at the same time strongly tolerant and exploratory. Other 35 species, mostly trees of the second-third size and high brushes reveal themselves as average and weak dominants, tolerants and explorants. They are, for example: Acer campestre L., Acer ginnala Maxim., Buxus sempervirens L., Caragana arbores­cens Lam., Crataegus monogyna, Gleditschia triacanthos L., Padus racemosa (Lam.) Gilib., Philadelphus coronarius L., Prunus divaricata, Rhododendron luteum Sweet, Rosa canina L., Salix caprea L., Salix triandra L., Sambucus nigra, Sorbus aucuparia, Syringa vulgaris, Taxus baccata L.

Such brushes as  Cotoneaster horizontalis Decne., Forsythia intermedia Zab., Forsythia suspensa (Thunb.) Vahl, Juniperus communis L., Juniperus sabina L. do not reveal remarkable dominant, tolerant and exploratory properties. It is connected with restricted habitus of their crown and low capability to autonomous renovation. Actually these bushes can be grown in park composition under conditions of proper attendance and artificial removal of competitors.

Grasses are not aggressive under canopy of park wood stand, but explerent properties of such species as Impatiens parviflora, Urtica dioica, Salvia glutinosa are evident. The species Geum urbanum, which is more widely spread in park phytocoenoses,  is able to form considerably tight root rosette, but is not capable to produce agressive pressure in seizing certain life space.

Sometimes a number of typical forest patients, such as: Anthriscus nemorosa, Galeopsis pubescens, Lysimachia nummularia, Glechoma hederacea, Galeobdolon luteum, Geranium robertianum, Carex sylvatica, Dryopteris filix-mas, Equisetum sylvaticum, Oxalis acetosella L., Stellaria holostea L., Hedera helix, Lamium purpureum L., Circaea alpina L., Asarum europaeum L., Pyrola rotun­difolia L., Pulmonaria obscura Dumort., Viola canina L. are found in park phytocoenoses.  

The following meadow species: Taraxacum officinale, Cirsium vulgare, Poa pratensis, Achillea millefolium, Poa nemoralis, Fragaria vesca, Poa trivialis, Potentilla erecta (L.) Raeusch., Plantago major L., Trifolium pratense, Trifolium sativum, Chelidonium majus L., are characterized by restricted tolerance properties, which is fairly rarely found under the canopy  of wood stand.

The above mentioned species interacting with each other, create certain coenosis-formed and stable groups in the course of time depending on their ecological-coenotic strategy. According to dominant phytocoenotic system the following variants can be singled out:

1.     Acer pseudoplatanus + Robinia pseudoacacia + Sambucus nigra + Geum urbanum;

2.     Betula pendula + Acer platanoides + Dactylis glomerata + Impatiens parviflora;

3.     Alnus glutinosa + Dactylis glomerata + Geum urbanum;

4.      Quercus robur + Quercus borealis + Acer platanoides + Geum urbanum;

5.     Acer pseudoplatanus + Acer platanoides + Sambucus nigra + Geum urbanum + Dactylis glomerata + Impatiens parviflora;

6.     Tilia cordata + Acer pseudoplatanus + Geum urbanum + Aegopodium podagraria;

7.     Larix decidua Mill. + Pinus sylvestris L. (Picea abies) + Acer pseudoplatanus +      Sambucus nigra + Geum urbanum + Urtica dioica.

Each of these variants is characterized by certain species satiety, structure, availability of relevant under-canopy hypersynusias.

Within the range of investigated park plantations of different ages the prevailing tendencies of forming and long stable existance of phytocoenoses with domination of autochthonous wood-brush and grass species were revealed: Alnus glutinosa, Acer platanoides, Acer pseudoplatanus, Betula pendula, Pinus sylvestris, Picea abies, Quercus robur, Tilia cordata, Sambucus nigra,  Aegopodium podagraria, Geum urbanum, Dactylis glomerata, Impatiens parviflora, Urtica dioica.  Among new introductions the dominant role is played  by  Robinia pseudoacacia, Larix decidua, Quercus borealis.