Synonyms

Ammophila breviligulata

  Basis for Listing

Ammophila breviligulata ssp. breviligulata (beachgrass) is typically a species of the Atlantic coastal region. Its inland distribution is limited to active dune habitats along the shores of the Great Lakes, reaching its western range limit in Minnesota. The only population in Minnesota occurs on Minnesota Point in Duluth at the western-most tip of Lake Superior (North Shore Highlands Subsection). Minnesota Point is part of one of the longest freshwater sandbars in the world. It stretches for more than 15 km (9.3 mi.) across Lake Superior from Duluth, Minnesota to Superior, Wisconsin. The portion that occurs in Minnesota is about 9 km (5.6 mi.) long and 0.5 km (0.3 mi.) wide. At one time, the sandbar provided continuous dune habitat. Most of this habitat has since been eliminated by residential, recreational, and commercial development. Today, probably no more than 3 km (1.9 mi.) of this habitat remains undeveloped. Pressures on the remaining habitat can be expected to increase and keep the future of A. breviligulata ssp. breviligulata in Minnesota uncertain.

There is a similar species native to Europe (A. arenaria [European beachgrass]) that has been introduced to North America. It is sometimes planted in sandy areas and dunes, but there are no records of it occurring in Minnesota. Recently, however, a strain of A. breviligulata obtained from a commercial source in Michigan was introduced on Minnesota Point for the purpose of stabilizing sand dunes. A published report (Holmstrom et al. 2009) has concluded that the Michigan introductions have a genetic advantage over the native Minnesota strain; it grows taller, produces more seeds, has longer rhizomes, and is more resistant to insect damage than the local strain, raising concern that it might displace the native strain. For these reasons, Ammophila breviligulata ssp. breviligulata was listed as a threatened species in Minnesota in 1984.

  Description

Ammophila breviligulata ssp. breviligulata is a distinctive, coarse, stiff perennial grass up to 1 m (39 in.) tall with long creeping rhizomes. Leaves are glaucous, stiff and rough, and the blades are in-rolled with long attenuate tips (Lakela 1965). The spikelet is one-flowered, awnless, and in a spike-like panicle. Lemmas have short hairs at their base.

Ammophila breviligulata ssp. breviligulata is distinguished from the similar Calamovilfa longifolia var. longifolia (prairie sandreed) in having glumes nearly equal in length, slightly exceeding the lemma and palea, with a cylindrical panicle. The short truncate ligule of A. breviligulata ssp. breviligulata differentiates it from the European A. arenaria.

  Habitat

The A. breviligulata ssp. breviligulata population on Minnesota Point occurs on sand dunes on the shore of Lake Superior. Its extensive rhizome system binds the sand, leading to additional dune formation. Minnesota Point appears to be the only place in Minnesota where suitable habitat exists. The North Shore of Lake Superior, as it occurs in Minnesota, is rocky or gravelly, which does not allow the establishment of this species. In contrast, the southern shore of Lake Superior, as it occurs in Wisconsin and Michigan, has broad sandy beaches that support a number of discontinuous populations.

  Biology / Life History

Ammophila breviligulata ssp. breviligulata is considered an “ecosystem engineer” because of its influence on the community and ecosystem by creating or altering the physical structure of its habitat (Emery et al. 2015). It does this by stabilizing sand dunes, thus altering the physical habitat of the whole plant community. This is accomplished by a remarkable system of underground rhizomes aided by an endophytic mycorrhizal fungus present in the habitat (Emery et al. 2015). It also produces seeds, but its primary method of spreading within its habitat is by growth of rhizomes. Rhizome fragments created by ice or storm events can also serve as propagules, because they have the ability to produce new shoots from dormant buds when they lodge in a new location (Maun 1984).

  Conservation / Management

Although a portion of the A. breviligulata ssp. breviligulata population was recently damaged by an airport expansion project, there are greater threats. For example, in an effort to protect residential dwellings that were built upon the dunes, non-native trees and shrubs were planted on the previously treeless dunes to try to minimize erosion. This failed to achieve its intended purpose but succeeded in degrading the natural qualities of the dunes. There is also a potentially serious threat caused by a non-native strain of A. breviligulata that was introduced from Michigan. It apparently has the capacity to outcompete the native strain and may eventually displace it. Plant surveys across Minnesota Point have found that the non-native genotype has already spread beyond its documented restoration areas and into native stands, particularly in foredune environments (Anderson 2006). All introduction of non-native strains of this species should end, and the continued advance of the non-native plants should be closely monitored. If it is ever deemed feasible, the non-native plants should be removed.

  Best Time to Search

The best time to identify Ammophila breviligulata ssp. breviligulata is from late June through September, when the inflorescence is fully developed.

  Conservation Efforts in Minnesota

A portion of the single A. breviligulata ssp. breviligulata population occurs in a state Scientific and Natural Area, which should protect it from development projects. However, this may not protect it from the potential threat posed by the non-native strain of beachgrass.

  Authors/Revisions

Welby R. Smith (MNDNR), 2021

(Note: all content ©MNDNR)

  References and Additional Information

Anderson (Holmstrom), R. M. 2006. The use of nonlocal propagules for habitat restoration: implications for a threatened population of Ammophila breviligulata in Minnesota. Thesis, University of Minnesota, Duluth.

Emery, S. M., and J. A. Rudgers. 2014. Biotic and abiotic predictors of ecosystem engineering traits of the dune building grass, Ammophila breviligulata. Ecosphere 5(7):1-18.

Emery, S. M., L. Bell-Dereske, and J. A. Rudgers. 2015. Fungal symbiosis and precipitation alter traits and dune building by the ecosystem engineer, Ammophila breviligulata. Ecology 96(4):927-935.

Holmstrom, R. M., J. R. Etterson, and D. J. Schimpf. 2010. Dune restoration introduces genetically distinct American beachgrass, Ammophila breviligulata, into a threatened local population. Restoration Ecology 18(2):426-437.

Laing, C. C. 1954. The ecological life history of the Ammophila breviligulata community on Lake Michigan dunes. Dissertation, University of Chicago, Chicago, Illinois. iv + 107 pp.

Lakela, O. 1965. A flora of northeastern Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 541 pp.

Maun, M. A. 1984. Colonizing ability of Ammophila breviligulata through vegetative regeneration. Journal of Ecology 72(2):565-574.