Dynamic and prognosis of development of park phytocoenoses, control of their structure

 One of the most important reasons of  change of appearance and structural-functional peculiarities of park plantations is dynamics of their volumetric-space structure which depends on growth rate of plants, their ecological-coenotic  strategy, in particular, capability to seize space of ecological gaps. The design of park complex has to foresee development of flora in time perspective of 20,40, 60 and more years. This prognosis can be performed by building up of relevant prognosis models which represent numerical characteristics and quality peculiarities of phytocoenoses at different stages of age development. In the course of time biometric parameters of separate coenopopulations are also changed in phytocoenoses (Table 3). 

Table 3

            Model of  development of wide spread park phytocoenoses with the following participation:   Acer                platanoides, Tilia cordata, Carpinus betulus, Robinia pseudoacacia, Aesculus hippocastanum,                                                                 Fraxinus excelsior

 In the process of natural development of park phytocoenoses the low-comfort hypersynusias with participation of Sambucus nigra and  Urtica dioica are formed. The broad-leaved autochthonous trees and introduced species acquire more edificator sense within composition of wood stand. As a rule, the species of conifer trees lose competitition and are oppressed. It results in decrease of sanitary-hygienic value of park plantations.

The given model is not complete, but visually illustrates some most important aspects of development of park phytocoenoses. Such models also have to take into account the processes of dropout of explorants, tolerants and wood species of shorter life span. Their further upgrading requires carrying out of special biometric research of growth progress and development of wide spectrum of wood and brush species under conditions of individual or group growth.  

In this regard it is necessary to stress out that the brush species with insignificant dominant, tolerant, and exploratory properties are not advisable to plant together with plants which are strong dominants and which will occupy the bigger part of vital space in the near future.  It results in oppression and extinction of highly decorative plants.

Strong dominants which are capable of forming the first storey of wood stand are advisable to plant together with weaker dominants which are distinguished by high shade tolerance, and thus can form the second storey of wood stand or brush canopy interesting in decorative respect .

From wood and brush species which have average and weak dominant, tolerant, and exploratory properties it is advisable to form bio-groups of open spaces at sufficient distance from strong dominants. For such groups periodic attendance is required.

The wood and brush plants with high exploratory properties should be used in limited numbers for forming of park plantations since they represent a threat for new  plantings.

From the point of view of aesthetics and comfort of park landscape the availability of formed under-canopy hypersynusia with participation of  Sambucus nigra and  Urtica dioica is not desirable here. It is better to fill their ecological gaps with other coenopopulations introducing hemi-cryptophytic species with high tolerance which are distinguished at the same time by high decorative value and are capable of adding more psycho-physical comfort to the park planting. The practice of introduction showed that for this purpose the more promising are ferns Dryopteris filix-mas, Matteuccia struthiopteris (L.) Tod., Athyrium filix-femina, Pteridium aquilinum (L.) Kuhn, Polystichum aculeatum (L.) Roth, Polystichum braunii (Spenn.) Fee. They are capable of forming powerful synusias in  plantings with light-requiring species under Carpathian and Roztochja conditions. Their phytomass fills up the under-canopy space replacing other grass species and supplementing composition of park landscapes owing to their bright green color. The special effect in park plantings can be produced by grass plant ephemers  Leucojum vernum L., Helleborus purpurascens Waldst. et Kit., Anemone nemorosa L., soil-covering creeping semi-brushes and liana  Hedera helix, Vinca major, bio-groups of perennials Hepatica nobilis Mill., Asarum europaeum L., Symphytum cordatum, shadow-resistant grass introducents Hosta ventricosa Stearn and Hosta lancifolia Engl., as well as their decorative cultivars and forms.

Periodically (once every 10-15 years) it is advisable to perform pruning for forming of crowns in park wood stand. Beginning from 50-year old age the planting should be pruned for forming landscape and removing short-life trees (birch, black locust, bird cherry trees, apple-trees etc). The clear cuttings that will appear at the place of removed trees will promote forming of semi-open landscape. The close synusias of grass plants and brush will be formed at the cuttings, which will add ornamental value to park plantings. Keeping semi-closed wood stands in the parks will ensure forming of specific insulation mode of semi-shading which is especially favorable for growth, development and spread of wide spectrum of autochthonous and stocking  species of plants, promoting support and spread of plant bio-variety of urbanized landscapes.

Penetration of rare kinds of plants such as  Epipactis atropurpurea into urban plantings is extremely interesting phenomenon in ecological aspect and desirable in floral regard. In general, the supervision over maintenance and expansion of plant bio-variety of urbanized landscapes has to be a part of local ecological monitoring.