Habitat change at a multi-species goose breeding area on Southampton Island, Nunavut, Canada, 1979–2010

Foraging by hyperabundant Arctic-nesting geese has significant impacts on vegetation of Arctic and subarctic coastal lowlands, but long-term data sets documenting these changes are rare. We undertook intensive surveys of plant communities at East Bay and South Bay, Southampton Island, Nunavut, Canada, in July 2010. Lesser Snow Geese, Ross’s Geese, Cackling Geese, and Brant nest and rear young at these sites; the first three have experienced up to 10-fold increases since the 1970s. At East Bay, we found significant declines in graminoids over the 31-year span, as well as significant declines in lichen and willow cover, and significant increases in rock cover. Transect data indicated graminoids were present at only 15%–36% of points at East Bay, whereas at South Bay, graminoids were present at 28%–90% of points. Moss was more prominent in transects at South Bay than at East Bay (40%–85% vs. 19%–42%), but quadrat data indicated much more of the moss cover at South Bay apparently was dead than at East Bay. Puccinellia phryganodes (Trin.) Scribn. & Merr. exceeded 1% in only two transects. Our data demonstrate a striking decline of preferred forage species and increases in non-forage cover, consistent with the hypothesis that changes resulted from persistent long-term foraging by the four species of breeding geese between spring arrival and late summer departure.

Systematics of three North American polyploid arctic alkali grasses (Puccinellia, Poaceae): morphology, ploidy, and AFLP markersThis paper is one of a selection of papers published in the Special Issue on Systematics Research.

We used flow cytometry, amplified fragment length polymorphisms (AFLP), and macromorphology from field and common garden specimens to delimit and identify parental taxa of three polyploid species of Puccinellia from the North American Arctic. Tetraploid Puccinellia bruggemannii T.J. Sørensen, hexaploid Puccinellia angustata (R. Br.) E.L. Rand & Redfield, and octoploid Puccinellia andersonii Swallen were generally separable based on ploidy and AFLP pattern, and showed allopolyploid origin. All three shared AFLP bands with at least two diploids and with Puccinellia phryganodes (Trin.) Scribn. & Merr., shown here to have both triploid and tetraploid populations in Canada. Approximately 10% of hexaploid individuals had AFLP patterns that were intermediate between P. angustata and P. bruggemannii, or P. angustata and P. andersonii, and occupied corresponding intermediate positions in morphological ordinations. Geographic distributions provide better support for introgression than for multiple polyploid events to account for these intermediate patterns. In common garden experiments, half of the characters had significantly different values between field and common garden specimens, but these plastic characters varied depending on the species pair analyzed and between experiments. Moreover, several characters were significantly different among species, but these characters were also different in each of the two experiments. Given this variation, we pooled the field and common garden data to determine important key characters by discriminant analysis of species pairs.

Genetic variation within and between populations of the asexual plant Puccinellia × phryganodes

Puccinellia × phryganodes (Trin.) Scriber and Merr is widely distributed in Arctic salt marshes. In North America the species, which is capable of extensive clonal growth, appears to be a sterile triploid (2n = 21); seed set has never been observed. Consequently it was predicted that the level of genetic variation would be low, both within and between populations. Examination of electrophoretic mobilities of isozymes of 12 enzyme systems in plants from three widely separated populations in Arctic Canada indicated a high level of variability both within and between the populations. The unexpected discovery of significant amounts of genetic variability suggests that sexual processes occur in this species.

Net aerial primary production of a James Bay, Ontario, salt marsh

Aboveground plant biomass and litter measurements were made at four intervals between mid-June and late August 1977 on a subarctic salt marsh located at North Point on the southwestern shore of James Bay, Ontario. We sampled six salt marsh zones ranging from a lower intertidal flat dominated by the grass Puccinellia phryganodes to the edge of willow thickets characterized by Juncus balticus.Peak aboveground biomass was reached in nearly all zones by early August, and ranged from 119.3 to 240.4 g dry weight∙m−2. Litter accumulated in all zones except the lower two zones which were subjected to tidal flows. The highest zone where Juncus balticus occurred had the highest litter mass, 572.8 g dry weight∙m−2, while the lowest, 24.7 g∙m−2, occurred in the lowest zone. Estimates of net aerial primary productivity using Smalley's method ranged from 119.3 g∙m−2 in the upper salt marsh to 384.0 g∙m−2 in the zone dominated by Juncus balticus. The mean marsh net aerial primary productivity was 227.7 g∙m−2 which was low compared with other salt marsh data. The 1977 aboveground biomass was lower in 1976, probably as a result of a cooler summer.

Vegetational development and the effect of geese on vegetation at La Pérouse Bay, Manitoba

The salt marshes at La Pérouse Bay, Manitoba, are described. Unconsolidated, water-saturated sediment is colonized by Hippuris tetraphylla, Puccinellia phryganodes, and Carex subspathacea. These sediments undergo frost heave, and on elevated mounds, Elymus arenarius var. mollis and Salix brachycarpa become established. This last species is the dominant one of the low willow tundra, which is the characteristic vegetation of the coastal strip. Where drainage is impeded in the upper marsh, relatively high salinities occur and species such as Salicornia europaea agg. and Triglochin maritima are present.A population of 10 000 to 20 000 lesser snow geese (Anser caerulescens) feed, in summer, on Puccinellia phryganodes, Carex subspathacea, Potentilla egedii, and Elymus arenarius var. mollis. The birds strip the shallow turf of Puccinellia in low lying areas between clumps of willow. This terracing of the surface creates depressions which become filled with water and ice. The role of geese in producing these ponds in the upper levels of salt marshes in the Arctic does not appear to have been reported previously. The ponds are subsequently colonized by Carex aquatilis and Triglochin maritima. The salt marsh gives way to an extensive fresh water marsh dominated by species of Salix, Eriophorum angustifolium, Calamagrostis neglecta, and Dupontia fisheri. The results are compared with data from other salt marshes in Hudson Bay and in the Arctic.

The vegetational zonation of the East Pen Island salt marshes, Hudson Bay

The extensive salt marshes at East Pen Island in Hudson Bay are described in quantitative terms and the well-marked sequence of species is characterized. The lower marsh is dominated by Puccinellia phryganodes and Carex subspathacea, with Hippurus vulgaris and Senecio congestus abundant in the salt pans. The midmarsh has well-developed swards of Dupontia fisheri and Celamagrostis neglecta, which give way to stands of Carex aquatilis in a well-developed freshwater marsh below the first beach ridge. The results are compared with other arctic salt marshes, and the development of a wide freshwater marsh in the upper zone of the salt marsh is described. This feature is perhaps unique to the Hudson Bay marshes and is a function of meltwater runoff from the surface of the permafrost table. This results in the high, standing water table at the top of the marsh, which is maintained by the permafrost table of the salt marsh itself.A transit survey of the marsh relates the quadrat samples to a high-tide datum point and allows interpretation of the vegetation sequence in terms of saltwater inundation. The depth of the active layer of the salt marsh is also described.