The impact of temperature on the northern distribution limits of the introduced species Fallopia japonica and Impatiens glandulifera in north-west Europe

This paper tests the predictions of sensitivity ana- lysis performed on two matrix population growth models, for annual and perennial vegetation (Woodward, 1988). Climatic correlations have been established for two intro- duced invasive plant species Fallopia japonica (Japanese knotweed) and Impatiens glandulifera (Himalayan balsam) in north-west Europe. These two species represent exam- ples of perennial and annual vegetation respectively. In accordance with the model predictions, the northern distri- bution limit of F. japonica was found to be controlled by two climatic variables-the length of the growing season, measured in day-degrees, and the minimum temperature- while for I. glandulifera only the length of the growing season was critical. Experimental verification of the results is crucial for understanding the mechanisms operating to limit plant distributions. By use of the predictions established by the climatic cor- relations for I. glandulifera and F. japonica, maps have been produced forecasting the potential northward spread of both species on the basis of a 1.5?C and a 4.5?C rise in global mean surface air-temperature. These temperatures represent the minimum and maximum increases predicted to occur by general circulation models for a doubling of CO2 concentration in the atmosphere. For a global tempera- ture increase of 1.5?C the maps demonstrate a maximum northward spread of F. japonica from a latitude of 63? to 68?N and for I. glandulifera from 64? up to 69?N. The greater temperature increase of 4.5?C indicates a consider- able potential for expansion in the range of F. japonica in Norway and Sweden but a distribution which was restricted along the eastern coast of Sweden and southern Finland. In contrast, I. glandulifera could colonize the whole of the Fennoscandinavian area. The predictions are made assum- ing no migrational lag and no soil 'incompatibility'. Geo- graphical differences in the patterns of spread between the species were explained with reference to the different factors affecting perennial and annual vegetation.

[1]  D. M. Gates.  Transpiration and Leaf Temperature , 1968 .

[2]  David J. Beerling,et al.  The effect of Riparian land use on the occurrence and abundance of Japanese knotweed Reynoutria japonica on selected rivers in South Wales , 1991 .

[3]  E. Maruta.  Growth and survival of current-year seedlings of Polygonum cuspidatum at the upper distribution limit on Mt. Fuji , 1983, Oecologia.

[4]  o. Prof. em. Dr. h. c. Heinrich Walter,et al.  Vegetation of the Earth and Ecological Systems of the Geobiosphere , 1983, Heidelberg Science Library.

[5]  Terry V. Callaghan,et al.  Effects on Ecosystems , 1992, Encyclopedia of Food and Agricultural Ethics.

[6]  C. Pigott.  Biological Flora of the British Isles. No. 174. Tilia cordata Miller. , 1991 .

[7]  Peter M. Vitousek,et al.  Biological invasions and ecosystem processes : towards an integration of population biology and ecosystem studies , 1990 .

[8]  A. Hansen,et al.  Biological Invasions in Europe and the Mediterranean Basin , 1990, Monographiae Biologicae.

[9]  A. Fitter.  An atlas of the wild flowers of Britain and northern Europe , 1978 .

[10]  A. J. Willis.  Plant diversity and change in a species-rich dune system , 1985 .

[11]  F. Woodward.  Climate and plant distribution , 1987 .

[12]  C. Pigott.  Fruit and Seed Production: Are the distributions of species determined by failure to set seed? , 1992 .

[13]  P. Kramer,et al.  Responses of Plants to Environmental Stresses , 1973 .

[14]  R. Schmid,et al.  Flowers of the Himalaya , 1985 .

[15]  Christophe Thébaud,et al.  Rapid invasion of Fraxinus ornus L. along the Herault River system in southern France: the importance of seed dispersal by water , 1991 .

[16]  A. P. Conolly,et al.  The distribution and history in the British Isles of some alien species of Polygonum and Reynoutria , 1977 .

[17]  D. Beerling,et al.  Impatiens Glandulifera Royle (Impatiens Roylei Walp.) , 1993 .

[18]  Alastair H. Fitter,et al.  Environmental physiology of plants , 1982 .

[19]  Woodward Fi.  Temperature and the distribution of plant species. , 1988 .

[20]  R. Lewin,et al.  Biological flora of the British Isles , 1948 .

[21]  Áskell Löve,et al.  Atlas florae Europaeae , 1977 .

[22]  Roger G. Barry,et al.  Mountain weather and climate , 1982 .

[23]  T. Saeki,et al.  TRANSPIRATION AND LEAF TEMPERATURE OF POLYGONUM CUSPIDATUM ON MT. FUJI , 1976 .

[24]  Brian Huntley,et al.  How Plants Respond to Climate Change: Migration Rates, Individualism and the Consequences for Plant Communities , 1991 .

[25]  A. Sakai.  Freezing Tolerance of Evergreen and Deciduous Broad-Leaved Trees in Japan with Reference to Tree Regions , 1979 .