Environmental Management (1995): 19(2) pp. 225-231
INTERACTIONS BETWEEN LYTHRUM SALICARIA AND NATIVE ORGANISMS:
A CRITICAL REVIEW
Mark G. Anderson
Department of Plant Biology
University of New Hampshire
Durham, New Hampshire 03824, USA
ABSTRACT
Seventy-one articles concerning Lythrum salicaria (purple loosestrife), a European herb introduced to North America, were reviewed for evidence of utilization by North American fauna and the effect of loosestrife on native plant species. In contrast to popular claims, 29 species of organisms were found to utilize this plant, and no evidence of species declines due to purple loosestrife were found. Evidence that loosestrife out-competes cattails and other plant species was found to be lacking or contradictory. Thus detailed, quantitative data are needed to understand loosestrife's natural history, population dynamics, and impacts on native ecosystems if we are to effectively manage this plant.
Proceedings of the Entomological Society of Washington (1986); 88(4): 748-759
INSECTS ASSOCIATED WITH PURPLE LOOSESTRIFE (Lythrum salicaria L.) IN EUROPE
S. W. T. Batra*, D. Schroeder, P. E. Boldt, and W. Mendl
*Beneficial Insect Laboratory, BBII
Agricultural Research Service, USDA
Beltsville, Maryland 20705
ABSTRACT
In Europe, 120 species of phytophagous insects, including 14 species apparently restricted to Lythrum, and 64 species of floral visitors were found associated with purple loosestrife (L. salicaria L.) Of potential value for the biological control of this aggressive alien weed in North American wetlands are: Dasineura salicariae (Cecidomyiidae); Hylobius transversovittatus, Nanophyes marmoratus, N. brevis (Curculionidae); Pyrrhalta calmariensis, P. pusilla, Aphthona lutescens, Altica lthri (Chrysomelidae); and Acleris lorquiniana (Tortricidae). Ecological, bionomic, and host-specificity investigations of these natural enemies are needed.
Journal of Ecology (1995) 83: 887-889
EVOLUTION OF INCREASED COMPETITIVE ABILITY IN INVASIVE NONINDIGENOUS PLANTS: A HYPOTHESIS
B. Blossey and R. Nötzold
New York Cooperative Fish and Wildlife Research Unit
Department of Natural Resources
Cornell University , Fernow Hall
Ithaca, New York 14853
NO ABSTRACT
Proc. VII. Int. Symp. Biol. Contr. Weed, 6-11 March 1988, Rome, Italy
Delfosse, E. S. (ed.) 1st Sper. Patol. Veg. (MAF), pp. 269-278. 1990.
AVAILABLE FEEDING NICHES IN POPULATIONS OF Lythrum salicaria (PURPLE LOOSESTRIFE) IN THE NORTHEASTERN UNITED STATES
Stephen D. Hight
United States Department of Agriculture
Agricultural Research Service, Beneficial Insects Laboratory
Building 476, BARC-East
Beltsville, Maryland 20705 USA
ABSTRACT
Lythrum salicaria, purple loosestrife, a native of Eurasia, was introduced into northeastern North America in the early 19th century. The plant has spread westward into the Great Plains and far West invading wetlands and displacing native emergent vegetation. Biological control is being explored as a control approach. Surveys of natural enemies present on L. salicaria were conducted in the northeastern U.S.A., and 59 species of phytophagous insects were collected: 50 species on foliage, three species on stems, six species on reproductive parts and no species on roots. None of these arthropods reduced populations of L. salicaria or caused appreciable damage to the plant. Therefore, all observed niches of L. salicaria studied are available for exploitation by introduced natural enemies.
Journal of Ecology (1986) 74: 133-141
GERMINATION OF TEN SHORELINE PLANTS IN RELATION TO SEED SIZE, SOIL PARTICLE SIZE AND WATER LEVEL: AN EXPERIMENTAL STUDY
P. A. Keddy and P. Constabel
Department of Biology
University of Ottawa
Ottawa, Ontario, Canada K1N 6N5
SUMMARY
(1) Lakeshore plants are distributed along a gradient of exposure to waves, from sheltered bays to exposed shorelines. Soil particle sizes vary along this gradient, and may influence germination and early establishment. We therefore tested whether species with different sized seeds germinate at different positions along a particle-sized gradient. In particular, we tested whether there was a shared preference over all species for one position on this gradient.
(2) Seeds of ten wetland plants (Acorus calamus, Alisma plantago-aquatica, Bidens cernua, B. vulgata, Cyperus aristatus, Lythrum salicaria, Polygonum punctatum, Sagittaria latifolia, Scirpus americanus, Typha angustifolia) were vernalized and then sown along a particle-size gradient with seven stages ranging from 0.125-0.250 to 8-16 mm. Two water levels, 1 cm and 4 cm below the soil surface, were provided. The proportion of seeds producing established seedlings was determined for each particle size and each species (n=5 replicates).
(3) In the drier treatment, nine out of ten species germinated differentially (P<0.05) along the gradient. In the wetter treatment, only three out of ten species so responded. Thus, soil particle size had most influence during drier conditions.
(4) In both wet and dry treatments, those species which did respond significantly (P<0.05) to the gradient had a shared preference for the fine soil (P<0.01). The single exception was Acornus calamus in the dry treatment.
(5) The species with the smallest seeds generally showed the greatest response to the gradient. Large-seeded species therefore had the broadest tolerances for variation in soil particle sizes.
(6) On lakeshores, the fine particle associated with sheltered bays would allow the highest recruitment irrespective of seed size. These effects would be most pronounced during periods of low water. The zonation of adult plants is apparently not produced by species with different-sized seed requiring different soil particle sizes for maximum germination.
Canadian Journal of Plant Science (1992); 72: 1305-1330
THE BIOLOGY OF CANADIAN WEEDS. 100. Lythrum salicaria
Tarun K. Mal1, Jon Lovett-Doust*, Lesley Lovett-Doust*, and G. A. Mulligan**
*Biological Sciences, University of Windsor
Windsor, Ontario, Canada, N9B 3P4
**Agriculture Canada, Research Branch
Center for Land and Biological Resources Research
Wm. Saunders Bldg., Ottawa, Ontario, Canada K1A 0C6
ABSTRACT
Lythrum salicaria is a serious weed in the wetlands of Canada, particularly in Ontario and Quebec. Indeed some assessments suggest that this exotic is now responsible for the conversion of more wetland habitat than is current human development pressure! Lythrum is a heterostylous species and clones by means of root buds. Despite its tristylous breeding system, Lythrum is a successful colonizer, and can produce prodigious numbers of seeds. It is likely that control can be achieved by hand-pulling in low-density populations, but once the species is established it generally becomes abundant and often approaches a monoculture. This species is particularly difficult to control because of its strong competitive ability, the extreme sensitivity of wetland habitats, and the likelihood of serious repercussions for wetland wildlife and fisheries if herbicides are used to control it. We see better possibilities for control through cultural techniques (e.g., manipulation of water levels to favor native species), enhancement of North American herbivores, and possibly, the introduction of biological control agents from Europe and Asia.
New York Fish and Game Journal (1984): 31(1); 81-87
ECOLOGICAL RELATIONSHIPS AMONG PURPLE LOOSESTRIFE, CATTAIL, AND WILDLIFE AT THE MONTEZUMA NATIONAL WILDLIFE REFUGE
Thomas J. Rawinski
Research Assistant
New York Cooperative Wildlife Research Unit
Cornell University; Ithaca, New York 14853
Richard A. Malecki
Assistant Leader
New York Cooperative Wildlife Research Unit
Cornell University; Ithaca, New York 14853
ABSTRACT
Interrelationships among purple loosestrife, cattail, and wildlife were studied at the Montezuma National Wildlife Refuge in central New York from 1978 to 1980. Stem densities of loosestrife increased in comparison with cattail when water levels were low and mud flats were exposed for seedling establishment. Permanent standing water (mean depth 40 centimeters) decreased loosestrife density, as did heavy interspersion with cattail. Muskrat activity favored expansion of loosestrife by selectively removing cattail. Grazing by white-tailed deer had little effect on loosestrife. Muskrats and long-billed marsh wrens used cattail stands almost exclusively, while red-winged blackbirds clearly preferred loosestrife. The ecological consequences of loosestrife invasion are discussed.
Journal of Ecology (1977) 65: 55-70
COMPARATIVE ECO-PHYSIOLOGY OF Epilobium hirsutum L. AND Lythrum salicaria L. III. MINERAL NUTRITION
S. R. A. Shamsi and F. H. Whitehead
Department of Botany
Imperial College
London, Ontario
SW7 2BB
SUMMARY
When plants of Epilobium hirsutum and Lythrum salicaria were grown in a standard nutrient solution and a series of its dilutions, it was found that at greater dilutions the growth of Epilobium hirsutum was reduced more than that of Lythrum salicaria. Moreover, L. salicaria responded to each successive dilution by an increase of root/shoot ratio. This proportionate increase in the root was at the expense of the stem rather than the leaves.
In a further experiment in which concentrations of individual elements were varied separately, growth of L. salicaria was found to be more affected by nitrogen than by phosphorus and potassium deficiency. In Epilobium hirsutum nitrogen and potassium deficiency had an equally depressing effect on growth and in extreme conditions potassium deficiency caused widespread necrosis and root malformation.
Reproductive development in the two species was also differently affected. While in Lythrum salicaria there was a progressive reduction in flowering and fruiting with increase in the deficiency of N, P and K, in Epilobium hirsutum even a moderate potassium deficiency completely suppressed flower and rhizome production.
These results are discussed in relation to patterns of ecological distribution of the two species. It is concluded that potassium deficiency may play a crucial and differentiating role in their establishment and growth.
United States Department of the Interior Fish and Wildlife Service
Fish and Wildlife Research 2, 1987
SPREAD, IMPACT, AND CONTROL OF PURPLE LOOSESTRIFE (Lythrum salicaria) IN NORTH AMERICAN WETLANDS
Daniel Q. Thompson*, Ronald L. Stuckey, and Edith B. Thompson
*Wildlife Editor (retired)
Editorial Office
U.S. Fish and Wildlife Service
Colorado State University
Fort Collins, Colorado 80523
ABSTRACT
Purple loosestrife (Lythrum salicaria L.) is an emergent aquatic plant of Eurasian origin; with the rise of marine commerce, it became established on all mid-latitude continents, except South America. L. salicaria arrived along the northeastern maritime coast early in the 19th century and has subsequently spread across mid-latitude North American wetlands. Several modes of colonization or escape were probable, including ship's ballast, livestock bedding and forage, wool and purposeful import as seeds or rootstocks for early gardens and herb beds. The gene pool shared by these immigrants accumulated over 50 years or more from a wide climatic and geographic range across Europe and Asia Minor. Rapid gene flow is inferred from the more or less equal distribution of three forms of flowers (short-, mid-. and long-style) occurring over Europe and North America. Purple loosestrife's plant associates in North America are cattails (Typha, spp.), reed canarygrass (Phalaris arundinacea), sedges (Carex, spp.), bulrushes (Scirpus, spp.), willows (Salix, spp.), and horsetail (Equisetum fluviatile), in the order mentioned. All of these plants have conspecifics (or nearly identical taxa) that are native to Eurasia, suggesting that L. salicaria was strongly preadapted to be a successful immigrant.
The bisexual flowers of purple loosestrife are insect-pollinated. Self-pollination is possible, but cross-pollination prevails. The period of bloom in most areas is from late June to early September. An old plant can produce more than 2 million seeds per growing season; sexual reproduction is of overwhelming importance. Seed dispersal is largely by drift in moving water; long distance spread is possible by seeds imbedded in mud or on water birds, trucks or off-road vehicles, or in the cooling systems of outboard motors. Erratic spread can also occur by purposeful introduction as a honey bee forage plant or by accidental escape from horticultural plantings. Seed samples from commercial suppliers of wildlife cover and prairie restoration plants have contained purple loosestrife seeds as an impurity. Seed longevity is at least 3 years with viability of 80 + %. Floating seeds or propagules must lodge on open, moist soil or saturated organic debris to take root. Once established, purple loosestrife can survive with 50% of full sun, but declines in vigor at low light levels. The plants can grow on a wide range of substrates, but are most sucessful on slightly acidic or neutral soils. L. salicaria has many ways of adapting to a wide range of habitats. It responds to soil nutrient (P and N) deficiencies by increasing the root to shoot ratio, to rising water levelrs by the growth of aerenchyma in submerged stem tissue, and to trampling, cutting or crushing or stems with root and shoot buds at the site of damage.
The spread and dominance of purple loosestrife in North American wetlands has shown a pattern of exponential increase that corresponds to the rate of exploitation of these habitats. With the construction of the eastern canal systems, and the extension of marine commerce into the Great Lakes, L. salicaria colonized the glacial marshes of the Midwest by 1900. By 1940, it was established in the Pacific Northwest and had begun to spread onto the Great Plains; by 1985, Alaska and Montana were the only states north of the 35 th parallel that had not reported purple loosestrife.
The impact of purple loosestrife on native vegetation has been disastrous, with more than 50% of the biomass of some wetland communities displaced. Monospecific blocks of this weed have maintained themselves for at least 20 years. Impacts on wildlife have not been well studied, but indicate serious reductions in waterfowl and aquatic furbearer productivity. Several declinng species of vertebrates are threatened with further degradation of their breeding habitats with the continued expansion of purple loosestrife. The plant's low palatability to livestock makes it a problem in wetland pastures in the West; it also threatens riparian hay meadows and off-water swlaes in irrigated areas in the West. Although L. salicaria can invade relatively undisturbed habitat, the spread and dominance of this weed have been greatly accelerated in distrubed habitats. Despite early control efforts in Quebec, and subsequent work in the United States, little research on purple loosestrife ecology and control has been done. Glyphosate has been used sucessfully, but no effort has been made to measure the impact of this broad-spectrum herbicide on native plant communities. Enough preliminary work has been done with biological control of purple loosestrife to suggest that this promises to ba a valuable approach.
On both regional and local scales, the rate of spread of L. salicaria has followed the logistic curve. At present, coping with purple loosestrife hinges on early recognition of the arrival of the weed and a conservation pattern of marsh management that avoids stressing native plant communities. Early detection allows local eradication to be carried out with minimum damage to the native plant community. Some form of integrated control is needed. California, Illinois, Ohio, Minnesota, and Wisconsin have taken prompt action to deal with this weed.
Aquatic Botany 38 (1990):303-309
SEED BANK DYNAMICS OF Lythrum salicaria L.: IMPLICATIONS FOR CONTROL OF THIS SPECIES IN NORTH AMERICA
Charles H. Welling and Roger L. Becker
Department of Agronomy and Plant Genetics
University of Minnesota
1991 Buford Circle
St. Paul, Minnesota 55108 U.S.A.
ABSTRACT
The seed bank of Lythrum salicaria L. was studied in wetlands of mid-continent North America where this Eurasian species is considered a nuisance. Recruitment under conditions chosen to promote high rates of germination did not exhaust the seed bank in a 1-cm deep layer of wetland soil in experimental flats. Emergence of seedlings from experimentally buries seed decreased linearly (P=0.0001, R2=0.89) from 90% at the soil surface to 0% at 2 cm. In the wetlands studied, there were 410 000 L. salicaria seeds m-2 in the top 5 cm of the soil; 37% of these were found below a depth of 2 cm. The implications of these results for the control of this species are discussed.
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