Wrack Burial Limits Germination and Establishment of Yellow Flag Iris (Iris pseudacorus L.)

Abstract

Seed burial under wrack, mats of water-transported plant debris, can limit recruitment of seedlings in wetlands. In a greenhouse experiment, we studied the effects of wrack burial (0, 1, 2, 4, 8 cm depths) on germination and emergence of the macrophyte Iris pseudacorus, native to Europe, Mediterranean Basin, and western Asia, that has invaded wetlands in nearly every global ecozone. We recorded the percentages of germinating, senescent, and quiescent seeds and evaluated seedling establishment and growth relative to substrate environmental variables. Seedling emergence of I. pseudacorus was reduced from >80% in controls without burial to <40% even at minimal wrack depths of 1 cm. Few I. pseudacorus seedlings were able to emerge from wrack burial of up to 8 cm in depth. We also found greater numbers of both quiescent seeds and germinated seeds that did not emerge from wrack burial. Reduced seedling emergence and increased seed quiescence with wrack burial were primarily explained by a reduction in daily temperature variation within the substrate. No senescent seedlings were observed with any depth of wrack burial. In view of our results, the management of I. pseudacorus invasion will be a long-term challenge, requiring continued control due to persistent seeds in wrack-buried seed banks.

Resolving the Puzzle of Iris maackii (Iridaceae): A Morphological Insight into Its Taxonomy

“…For this reason, the study of the morphological characters of I. maackii, as determined by its nomenclatural type, will contribute to the understanding of its taxonomy. This circumstance can undoubtedly improve the monitoring of the species' invasion and help adjust the biocontrol program for I. pseudacorus [40][41][42]. Regarding I. pseudacorus, it is necessary to pay special attention to some of its biological characteristics.…”

Plant Invasion Ecology

“…Several articles within the topic deal with reproductive traits, which are known to play a substantial role in the spread and establishment of alien taxa [4]. Potential fecundity was studied in Cytisus scoparius (Fabaceae) within its native and alien ranges [5], while seed germination under different conditions was investigated for Iris pseudacorus (Iridaceae) [6], Prosopis juliflora [7], and Acacia mearnsii [8] (both Fabaceae).…”