population biology of alien invasive plants

In the last two decades biological invasions have drawn increasing attention. Compared to other subjects of ecological investigation, studies related to biological invasions have almost exploded in number during the last years. The fact that an increasing number of ecologists gets caught up in the problem of biological invasions can be attributed to several reasons. First, biological invasions are increasingly recognized as one of the most important threats to biodiversity, i.e. biological invasions tend to homogenize the earths biota. Second, biological invasions can also pose severe environmental, economic and sometimes even health threats.

Invasive species affect native species and ecosystems by competing directly for resources that native species require, by altering ecosystem functions and processes such as nutrient and hydrologic cycles, and fire frequency and/or intensity. There are virtually no natural areas left that have not felt the impact of non-native invaders. Third, biological invasions represent great natural experiments for the ecologist whose investigation is extremely valuable for the understanding of population spread  and community- and landscape-level processes affecting the patterns and abundance of species at large spatial and temporal scales, i.e. scales which are otherwise hardly accessible for experimental ecologists. Furthermore, research is increasingly focusing on the problems related to global change, which include biological invasions because species invasions do not only respond to but are also an integral part of global change. In addition, biological invasions are still increasing due to increasing transport, commerce and changing land use regimes (Dietz & Steinlein 2003).

In our department we are currently working on: Prunus serotina and Heracleum mantegazzianum, two invasive species causing problems in pine forests in the "Senne"area and on ruderal sites in Bielefeld.

Publications:

Dietz, H. & Steinlein, T.  Recent advances in understanding plant invasions   Progress in Botany 65 (in press)

Steinlein, T. & Dietz, H. (2002) Don’t do anything!? Implications of intensive basic research for successful management of the invasive alien plant species Bunias orientalis L. (Brassicaceae). in: Kowarik, I & Strafinger, U (eds) Biologische Invasionen: Herausforderungen zum Handeln. Neobiota Band 1.

Dietz, H., Steinlein, T., Ullmann, I. (1999) Establishment of the invasive perennial herb Bunias orientalis L.: An experimental approach. Acta Oecologia 20: 621-632.

Dietz, H., Steinlein, T. (1998) The impact of anthropogenic disturbance on life stage transitions and stand regeneration of the invasive alien plant Bunias orientalis L. - In: U. STRAFINGER, K., EDWARDS, I., KOWARIK, M., WILLIAMSON (eds) Plant Invasions: Ecological Mechanisms and Human Responses p. 169-184 Backhuys Publishers, Leiden.