Prairie marshes in western Canada, with specific reference to the ecology of five emergent macrophytes

Abstract

Prairie marshes in western Canada occur in the Manitoba, Saskatchėwan, and Alberta plains, from 49 to between 50 and 53° N. They are dynamic habitats characterized by fluctuations in water levels and water chemistry. Marsh habitats form an east–west gradient that involves a decrease in precipitation (525 – 350 mm year−1) and an increase in its variability. Within the region, water salinity ranges from fresh to hypersaline. Water levels and chemistry coupled with life history features influence the distribution and successional role of emergent macrophytes. Five dominant emergents have aboveground standing crops of between 425 (Scirpus lacustris ssp. glaucus) and 1750 g m−2 (Typha latifolia). They vary in reproductive strategy and tolerance to water levels and salinity. Scirpus lacustris ssp. glaucus grows in deep water with conductivities < 15 mS cm−1, and spreads vegetatively. Typha latifolia, tolerant of water fluctuations and salinity < 10 mS cm−1, spreads both vegetatively and by seed, particularly under drawdown. Phragmites australis tolerates a wide range of moisture conditions and salinities (< 20 mS cm−1). It propagates primarily by rhizomes and runners. Scirpus lacustris ssp. validus thrives under unstable water regimes but is saline intolerant (< 2 mS cm−1). It is short lived (±3 years) and reproduces primarily by seed. Scirpus maritimus var. paludosus, which dominates western wetlands, tolerates hypersaline conditions (±45 mS cm−1), prefers changing water levels, and spreads both vegetatively and by seed. These environmental and life history features help elucidate wetland dynamics.

Long-term effects of a Phragmites australis invasion on birds in a Lake Erie coastal marsh

“…Introduced P. australis can grow in a wide range of water depths, from areas where the water table is a meter below the soil surface to standing water greater than 50 cm deep (Shay and Shay, 1986). Experiments growing P. australis in variable water depths, reaching up to 230 cm, have revealed developmental plasticity in P.…”

“…In deep water, 70 -75 cm, P. australis allocates less biomass belowground and makes fewer, taller shoots which serve to increase gas exchange but can make the plant more vulnerable to wave action (Vretare et al, 2001). This may be the reason that introduced P. australis in natural settings seems limited to water depths less than 100 cm and its growth is restricted under prolonged flooding (> 100 days) (Hudon et al, 2005;Shay and Shay, 1986). …”

“…The diameters of native rhizomes are less than 15 mm, while introduced rhizomes are flatter and greater than 15 mm in diameter (Mal and Narine, 2004). Introduced P. australis allocates 60 -70% of its total biomass to roots and rhizomes (Mal and Narine, 2004;Shay and Shay, 1986), creating extensive networks that capture soil nutrients. Rhizomes can mobilize resources and allocate them to younger, smaller shoots during the early growing stage to achieve a more uniform final stand structure (Hara et al, 1993).…”

Migrating and breeding bird use of restored shallow lakes in Iowa

“…On the other hand, bulrushes (Schoenoplectus sp.) can grow in deep water (Shay and Shay 1990), but we seldom encountered these species. Along with the sampling technique, this could also be related to wetland condition or competition with other dominant emergent species (Day et al 1988, Green and.…”

“…Along with the sampling technique, this could also be related to wetland condition or competition with other dominant emergent species (Day et al 1988, Green and. Bulrushes can grow in a range of water depths and conditions, but prolonged flooding may cause this group to decline over time Marshall 1963, Shay andShay 1990). They may also be outcompeted from Typha sp.…”