Pattern and process in invasion ecology
Article first published online: 25 DEC 2001
Global Ecology and Biogeography
Volume 9, Issue 1, pages 93–94, January 2000
How to Cite
Thompson, K. (2000), Pattern and process in invasion ecology. Global Ecology and Biogeography, 9: 93–94. doi: 10.1046/j.1365-2699.2000.00211.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
Brock, J.H., Wade, M., Pysek, P. & Green, D. (eds) (1997) Plant invasions: studies from North America and Europe. Backhuys Publishers, Leiden. viii + 224 pp, figs, tables, photos, index. Paperback: Price: US $52.75. ISBN 9 073 34823 4.
Books on plant invasions seem to have become rather invasive themselves in recent years. In addition to a number of one-man efforts, there have been a series of volumes edited by Max Wade and any three others — first de Waal et al. (1994) , then Pysek et al. (1995) , and now the present volume, which derives from a workshop at Arizona State University in 1995. As well as partly sharing a stable of editors, the three volumes also share many authors. Six authors in the present volume have appeared in all three, while another six have appeared in one of the previous books. This book, then, must be seen in context as one of a series. The first book was restricted to the ecology and management of just five riparian aliens, the second was much more wide-ranging, and the new one is somewhere in the middle.
Four authors (Caffrey, Darby, Philp and Tiley) who wrote about Heracleum mantegazzianum in the first book return to the topic here. The earlier papers were concerned largely with control measures, but here we learn a lot more about the biology and dynamics of H. mantegazzianum. To me, the most surprising news was that this species, although it continues to spread to new sites in Northern Ireland, is dying out at existing sites at a higher rate. Nobody seems to have any idea why.
The book opens with an interesting general chapter by Max Wade. The fact that this chapter is called Predicting plant invasions: making a start suggests (correctly) that we are still a long way from being able to do this with any great accuracy. There is nothing here about the biology of invasions that has not been said before, but it is useful to be reminded of some particularly difficult questions. For example, is there some inherent biological reason why most invasive plants spend years or decades in a lag phase before becoming invasive, or is the invasive stage triggered by some external event (a topic covered at length by Kowarik in the 1995 book)? Just why is it that of all the Impatiens species imported to the UK, I. glandulifera is the only one to have become a real problem? Wade also makes some useful points about the attitudes of government and NGO’s to invasive plants. Thus, although Crassula helmsii was correctly predicted to be a potential problem years ago (and now is a problem), there is no infrastructure for dealing with potential invaders in the UK (or anywhere else). He also points out the benefits of more international cooperation, as plants that are actively invasive in one country may still be in the lag phase elsewhere, and thus more easily controlled or even eradicated. We are reminded of this later in a short paper by Seiger, which makes the point that Fallopia japonica is not yet the problem in the USA that it is in Europe, but it soon will be.
The north American theme continues in a series of largely descriptive papers on riparian aliens in Phoenix (by Brock and Farkas and by Green and Baker) and elsewhere in Arizona (Stromberg, Gengarelly and Rogers), two papers on Lepidium latifolium (Young, Palmquist and Wotring, and Blank and Young), Schinus terebinthifolius in the Everglades (Jones and Doren), Arundo donax in California (Bell) and Tamarix ramosissima in New Mexico (Duncan). The Americans get their own back in two papers on New World aliens in Europe: Bidensfrondosa (Keil) and Prunus serotina (Starfinger). Together these papers begin to build up a picture of the worst invasive species: large size, high growth rate, clonal growth, vigorous regrowth after damage, ability to establish from root or rhizome fragments and often copious seed production. They also highlight the importance of river corridors for dispersal and establishment, although the paper by Andersen illustrates that this need not always be the case. In SW Denmark most aliens of seminatural habitats are trees and shrubs invading heathland, a pattern which presumably reflects the high invasibility of this habitat following the relaxation of traditional management. Two more papers return to the human dimension of weed spread and control. Pysek and Mandak report the huge increase in aliens in the flora of several Czech villages between 1980 and 1995, which they attribute largely to several different effects of the arrival of private enterprise. Child and de Waal show how a GIS can help local authorities to keep track of Fallopia and prevent its spread by incorporating its distribution into the planning process. Finally, a rarity in this area — an experimental paper. Bastl, Kochar, Prach and Pysek show both how difficult it is to predict invasibility, and how poor at invading some classic invaders actually are. Which all points, I suspect, to the key roles of repeated introductions and, most importantly, planting in the invasion process.
A book which should be read, at least in part, by all those interested in invasive plants.