Występowanie drzew obcego pochodzenia na tle zróżnicowania lasów Polski południowej

Anna Gazda

Abstract

The major aim of different ecological studies is to understand the processes underlying success of some alien species as a species spontaneously spreading into a new environment, far from the limits of its natural range. Knowledge and understanding of the processes of invasiveness of alien species as well as invasibility of native habitats is now one of the most important problems of modem ecology. Despite many studies on invasive plant, undertaken in different countries, it is very difficult to resolve many problems tightly connected with invasive ecology. Till now there are much more data collected on grasses and forts in grassland ecosystems in comparison to tree species in forest ecosystems. Planted alien trees and shrubs are present in Polish forests for many years. Woody species are not considered to be a very invasive species, although many alien trees were planted around the world. Last time many non-native woody species have spontaneously spread into natural ecosystems. In recent years, it was noted that for some alien species that their expansion may lead to significant changes, through the dominance and displacement of native species with some natural habitats. A very important factor influencing the success of alien plant is diversity of native plants and the degree of vegetation naturalness. More natural and divers forests covered protected areas in southern part of Poland are considered to he much more resistant to plant invasions than managed forests in lowland. This study was focused mainly on qualitative and quantitative relation between native and non-native tree species occurred within temperate forests differed by a function. The first one is a. managed forest and the second one is located within protected area. Because of the aim of the study this research represents an important contribution to study the impact of: I) altitude, 2) number of mature alien trees ('propagule pressure'), 3) naturalness or 4) diversity on invasibility of polish forests. Researches were conducted in the forests of southern part of Poland (Fig. 1, Appendix). Data were collected on almost 1000 sample plots (100 m2). Within every sample plots there were measured: diameter at breast height of all trees with DBI-I 7.0 cm, height of trees; next there were identified and counted seedlings (divided into two groups: one-year old seedlings, and older seedlings but individuals did not exeed 50 cm in height) and saplings (individuals exceeded 50 cm in height but with DBH < 7cm), at last there were identified all herbaceous and woody species within forest floor layer and it was estimated its percentage cover. This method of data collection allowed us to compare the dynamics of natural regeneration of alien species to the dynamics of native species. In this way we can describe in number intensity of the observed processes. From the standpoint of risk assessment it is important to compare the dynamics of the same processes but for a different species: native and non-native in the same temporal and spatial scale. The most frequent and abundant alien tree species in Polish forests are: northern red oak, black locust, Wejmuth pine and horse chestnut among the woody plants. Alien tree species are the most numbered in uplands and almost absent in montane forests. Very often it was assumed that northern red oak is unable to regenerate under a canopy consisted of the same species. Now it is observed that within a new area it is usually 'facilitated' by mature tree. Quercus nibra used to regenerate under canopy composed of at least one individual of the same species with a high probability. However it is moved to new areas by birds (Eurasian Jay), too. It is able to colonize new sites; in comparison to stands with a mature individuals of this species it was noticed a few times, often within stands without any mature individuals in a forest canopy. Seedlings and saplings of northern red oak were more abundant within Ojcow National Park due to individuals present in a stand located very close to the border of this area. Non-native tree species are able to colonize new areas and to converse properties of occupied habitats. Sometimes it is very easy to cut all mature individuals in occupied area but very often it is difficult to remove all diaspores. In European forests the most invasive species is Rictus serotina. It is moved by birds into new areas. After cutting of all individuals it is able to come back. Under this species native tree species regenerate very rare. Northern red oak is not so invasive yet, but it is able to change soil feature. Under this species forest floor is very poor: usually it is described as nudurn or consisted only of gasses. Non-native tree species are not so frequent and abundant as native species. But their contribution is increasing in a spatial and temporal scale. In order to test the next hypotheses we gave the rank of the degree of forest naturalness based primarily on the species composition of tree layer (was this the same as in the natural forest-potential vegetation), the origin of the tree species (natural regeneration or artificial), form and intensity of forest use in the past and the structure of the tree layer. We concluded that the habitat transformed by human activities was a more invasisible than a more natural habitat. At least we conducted testing the Stohlgrens hypothesis, analyzed the effect of species richness on the number of alien species that inhabit a given area. On the basis of these studies we determined that native species richness affects the settlement of non-native plants in our forest following Stohlgren hypothesis ('rich get richer'). We ought to prepare special kind of strategies to control alien species mainly in protected areas. To be able to create this plan we have to: at first assess pressure of alien species (their names, number, frequency and distribution) within any protected area as well as within areas surrounding these areas as potential sources of seed or fruit of non-native plants, then know how to prevent spread of a new alien species, which is present outside protected area, but within the area which is located very close to a protected area; third one we want to describe predictive model of spreading of invasive or potential invasive species both in natural forest and in managed forest. The prevention of alien species is a very important activity against invasive species. This is the most efficient approach to protect all natural values of a protected area from the harmful effects of invasive plants. Prevention is closely related with the identification of both invasive species and invasion pathways.
Other language title versionsDistribution of alien tree species in various forest communities of southern Poland
Book typeMonograph
Other categories ROZPRAWA_HABILITACYJNA
Author Anna Gazda (FoF / IoEaS)
Anna Gazda,,
- Institute of Forest Ecology and Silviculture
PublisherUniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW [80]
Publishing place (Publisher address)Kraków
Issue year2013
Book series /Journal (in case of Journal special issue)Zeszyty Naukowe Uniwersytetu Rolniczego im. Hugona Kołłątaja w Krakowie. Rozprawy, ISSN 1899-3486, (0 pkt)
Vol512
No389
Pages117
Publication size in sheets9.5
Internal identifierWL/16/9
Languagepl polski
Score (nominal)25
Citation count*4 (2020-04-10)
Additional fields
UwagaIlość ark.wyd. ustalono na podst informacji umieszczonej w stopce redakcyjnej
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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