Vegetation patterns in James Bay coastal marshes. II. Effects of hydrology on salinity and vegetation

1988 ◽  
Vol 66 (12) ◽  
pp. 2586-2594 ◽  
Author(s):  
Jonathan S. Price ◽  
Kern Ewing ◽  
Ming-ko Woo ◽  
Kenneth A. Kershaw

The vegetation of a coastal marsh in southern James Bay was examined in reference to the salinity and hydrological processes. Regional hydrologic influences related to the freshwater budget of James Bay reduce the local salinity so that the vegetation typifies that of a fresh to brackish marsh system, in contrast to the Hudson Bay salt marshes reported in the literature. Thus species that thrive in areas of higher salinity have only limited occurrence at the study site. Infrequent tidal inundation of low salinity bay water diminishes surface salinity, which is primarily controlled by the interaction of marsh hydrology with fossil salt diffusing upward from postglacial deposits. The soil water salinity increases with depth and distance inland. However, local hydrologic gradients near raised beach ridges and incised stream channels affect surface runoff and groundwater recharge and discharge, producing further distinct spatial variations in salinity. These processes thus control the distribution of saline water in the rooting zone and hence the patterns of vegetation.


1986 ◽  
Vol 64 (1) ◽  
pp. 217-226 ◽  
Author(s):  
Kern Ewing ◽  
K. A. Kershaw

Coastal wetlands of the Hudson Bay Lowlands along southern James Bay are generated by a positive water balance, low relief, and a rising land surface. Marshes, dominated by sedges and grasses, and separated by beach ridges, occur between unvegetated intertidal flats and the inland boreal forest. Bay waters, affected by currents, shallow depths, and large freshwater inputs from major rivers in the Hudson Bay drainage, are brackish. Off the coast at the Harricanaw River, surface salinity in the bay is <4 ppt while soil water salinities in the adjacent marsh are higher. Standing water and tidal water in contact with vegetation often measure 0 ppt salinity. Plant communities adapted to brackish water have developed. Using two-way indicator species analysis classification, twelve widespread community types were recognized. Ordination using detrended correspondence analysis revealed gradients of salinity, elevation, drainage, vegetation development, complexity, and peat formation, and separated coastal from estuarine communities. An inverse salinity gradient, which has been reported elsewhere in James Bay, was not found; explanations are proposed for isolated areas of high salinity.



2006 ◽  
Vol 84 (11) ◽  
pp. 1732-1739 ◽  
Author(s):  
P. C. O ◽  
P. M. Kotanen ◽  
K. F. Abraham

In coastal marshes on James Bay and southern Hudson Bay, Canada, the grass Festuca rubra L. is heavily used for forage by both Snow (Chen caerulescens caerulescens (Linnaeus)) and Canada Geese ( Branta canadensis (Linnaeus)). On Akimiski Island, James Bay, this grass occurs in a mosaic of short, heavily grazed patches and tall, lightly grazed patches. We investigated whether short plants are primarily a plastic morphological response to grazing by geese. Over two growing seasons, we measured growth of short patches protected from grazing and of tall patches subjected to mowing treatments, with unmanipulated short and tall controls. Protection resulted in rapid conversion from a short growth form to a tall form, similar in height and biomass to plants in tall control plots. Mowed tall plants also rapidly recovered to near tall control values for height and biomass. A single 3 week treatment episode often permitted nearly full recovery to tall form. In some cases, more sustained protection was required, but repeated mowing ultimately may have reduced growth rates. These results indicate that the morphology of individual plants of Festuca rubra plastically recovers from changes in defoliation pressure. Consequently, short patches likely represent grazing lawns maintained by intensive foraging by geese.



1987 ◽  
Vol 65 (7) ◽  
pp. 1410-1419 ◽  
Author(s):  
S. L. Wolff ◽  
R. L. Jefferies

Morphological and electrophoretic variation has been documented within and among populations of Salicornia europaea L. (s.l.) in northeastern North America. Univariate and multivariate analyses (discriminant analyses) of measurements of floral and vegetative characters delimited three morphologically distinct groups of populations: Atlantic coast tetraploids (2n = 36), Hudson Bay diploids, and Atlantic coast and James Bay diploids (2n = 18). The two diploid groups were morphologically distinct from the midwestern diploid, S. rubra Nels., based on anther length, width of the scarious border of the fertile segment, and the overall width of the fertile segment. Electrophoretic evidence supported the delimitation of the three distinct morphological groups of populations of S. europaea with the exception of the population from James Bay, which had electrophoretic patterns identical with those of plants from Hudson Bay but resembled the Atlantic coast diploids morphologically. Most enzyme systems assayed were monomorphic. Only homozygous banding patterns were detected in diploid plants and electrophoretic variation was not observed within populations of S. europaea or S. rubra but was detected between groups of populations. Four multilocus phenotypes were evident; these corresponded to the major groups recognized on the basis of ploidy level and morphology. Reasons that may account for the paucity of isozymic variation are discussed.





1989 ◽  
Vol 67 (10) ◽  
pp. 2967-2974 ◽  
Author(s):  
J. C. Earle ◽  
K. A. Kershaw

Plant zonations and selected environmental variables were studied in a subarctic coastal marsh at Ekwan Point, James Bay, Ont. Eight distinct community types were identified using two-way indicator species analysis classification (TWINSPAN). These were interpreted as a primary successional sequence. The eight communities were found to conform closely to the classical marsh zonations based on elevation and tidal influence: (1) lower salt marsh, (2) middle salt marsh, (3) upper salt marsh, (4) saline meadow, (5) freshwater meadow, and (6) freshwater fen. Environmental data collected along the vegetation transects indicated that changes in elevation and soil-water salinity probably influence species distributions. A species ordination using detrended correspondence analysis (DECORANA) revealed several trends in plant distribution patterns. Consideration of the environmental affinities of species separated along three ordination axes suggested that salinity and elevation, water content, and soil texture were probably important factors influencing successional processes in the marsh during at least the last century. An inverse salinity gradient, which has been reported at many sites along the west coast of Hudson and James bays, was not found at Ekwan Point.



1932 ◽  
Vol 7 (1) ◽  
pp. 91-118 ◽  
Author(s):  
H. B. HACHEY

The waters of Hudson bay differ markedly from the waters of Hudson strait and the waters of the open ocean. Intense stratification in the upper twenty-five metres, decreasing as the waters of the open ocean are approached, gives Hudson bay the character of a large estuary. Below fifty metres the waters are for all purposes dynamically dead, thus resulting in a cold saline body of water which probably undergoes very little change from season to season. The movements of the waters at various levels are dealt with to show that the inflow of waters from Fox channel and the many fresh-water drainage areas control the hydrographic conditions as found. The main water movement is from the James bay area to Hudson strait and thence to the open ocean.





1984 ◽  
Vol 3 (2) ◽  
pp. 191-200 ◽  
Author(s):  
S.J. Prinsenberg
Keyword(s):  


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