The negative impact of intentionally introduced Quercus rubra L. on a forest community

Abstract

<p>Some alien woody species used in commercial forestry become invasive and, as invaders, cause major problems in natural and semi-natural ecosystems. However, the deliberate introduction of aliens can bring unintended negative changes also within areas of their cultivation. This paper presents the effects of the intentional introduction of the North-American <em>Quercus rubra</em> in European mixed Scots pine-Pedunculate oak forests (POFs): <em>Querco roboris-Pinetum</em> (W. Mat. 1981) J. Mat. 1988. Phytosociological data from field research combined with GIS data analysis of the current distribution of Northern Red oak in the studied habitat were used to determine the composition and structure of forest communities in plots with and without <em>Q. rubra</em> participation. </p><p>The results show that <em>Q. rubra</em> significantly reduces native species richness and abundance, both in old-growth and in secondary (post-agricultural) forests. Not one resident vascular plant benefits from the introduction of Northern Red oak and only a few are able to tolerate its co-occurrence. The natural restocking of all native woody species is also strongly limited by this alien tree. </p><p>The introduction of Northern Red oak significantly limits the environmental functions of the POF ecosystem and weakens its economic and social aspects. However, its further cultivation is justified from an economic point of view, as the essential function of the studied forests is commercial timber production, and the introduction of this fast growing alien tree supports the provisioning ecosystem services. A clear description of the level of trade-off between the accepted negative and positive effects of the introduction of <em>Q. rubra</em> on forest ecosystem services requires further interdisciplinary studies.</p>