Competitive abilities of native European and non-native North American populations of Lythrum salicaria L.
2007
Edwards, K. R., University of South Bohemia, České Budějovice (Czech Republic). Faculty of Biological Sciences. Department of Ecology | Květ, J., Academy of Sciences of the Czech Republic, Třeboň (Czech Republic). Institute of Systems Biology and Ecology | Adams, M. S., University of Wisconsin, Madison, Wisconsin (USA). Department of Botany
As expressed by the evolution of increased competitive ability (EICA) hypothesis, non-native invasive plants are larger than plants of the same species growing in their native range as a result of changed dry weight allocation patterns. This should result in a greater competitive ability for the non-native populations. Competitive abilities and dry weight allocation patterns for North American non-native and native European Lythrum salicaria populations were tested against each other in a three-year common garden experiment using a replacement series design. Plants were grown across a range of nutrient and water levels to determine differential environmental effects of these two factors. Shoot height, stem number and flowering phenology were measured annually. The plants were harvested after three years and their dry weight allocation patterns determined. Shoot heights and stem numbers were positively related to nutrient levels but few significant between-population differences were found. The non-native North American plants flowered significantly later than those from native European populations. Competitive ability, measured as relative yield and relative yield total, was also not significantly different in most cases. Differences in dry weight allocation patterns depended upon the particular populations being analysed. The results of this study do not support the predictions of the EICA hypothesis for this species under the tested conditions. Other factors, such as where a population falls along environmental and latitudinal gradients, day length, or adaptation to local conditions, may be more important in explaining the greater growth and later flowering phenology seen in the non-native populations.
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