Standing crop of Sagittaria in the Upper Mississippi River

1985 ◽  
Vol 63 (8) ◽  
pp. 1453-1457 ◽  
Author(s):  
William R. Clark ◽  
Robert T. Clay
Keyword(s):  
Particle Size ◽  
Water Depth ◽  
Mississippi River ◽  
Standing Crop ◽  
Open Water ◽  
Growing Season ◽  
Upper Mississippi River ◽  
Sagittaria Latifolia ◽  
Average Water ◽  
Water Depths

Aboveground and belowground standing crops of Sagittaria latifolia and Sagittaria rigida were related to water depths and substrate particle-size distribution, in differing parts of Pool 9 of the Upper Mississippi River. Average water depth during the growing season was greater in stands in open-water areas (30.1 ± 2.1 cm) than in backwaters (16.5 ± 1.5 cm). The average water depth of 35.1 in S. rigida stands was deeper than the average of 26.4 cm in S. latifolia beds. Sediments in backwaters had significantly greater proportions of clay- and silt-sized particles than sediments in open waters. Density of S. latifolia in open water was 31.0 ± 1.3 compared with 22.7 ± 1.6/m2 in backwaters. Peak aboveground standing crop of S. latifolia in open water (683.4 ± 41.4 g/m2) was greater than in backwaters (430.9 ± 25.7 g/m2) and varied directly with differences in water depths in stands among years. Belowground standing crop of S. latifolia in open water (58.6 ± 4.3 g/0.25 m2) was also greater than in backwaters (40.9 ± 6.6 g/0.25 m2). During the growing season, approximately 46% of the belowground standing crop of this species was composed of tubers. Peak aboveground standing crop of S. rigida in open water (498.2 ± 35.5 g/m2) was greater than in backwaters (422.1 ± 26.3 g/m2), but a correlation with water depth was not found. Belowground standing crop of S. rigida in open water (39.3 ± 4.0 g/0.25 m2) was greater than in backwaters (25.6 ± 3.3 g/0.25 m2). Tubers constituted 61% of belowground standing crop of S. rigida, which was greater than the proportion for S. latifolia. Shallower water depth and finer particle size caused by siltation in backwater Sagittaria beds result in stands which are less productive.

scholarly journals Soil spatial variability and the estimation of the irrigation water depth

2001 ◽  
Vol 58 (3) ◽  
pp. 549-553 ◽  
Author(s):  
Klaus Reichardt ◽  
José Carlos de Araújo Silva ◽  
Luis Henrique Bassoi ◽  
Luís Carlos Timm ◽  
Julio Cesar Martins de Oliveira ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Soil Water ◽  
Water Depth ◽  
Irrigation Water ◽  
Field Capacity ◽  
Phaseolus Vulgaris L ◽  
Water Value ◽  
Average Water ◽  
Water Contents ◽  
Water Depths

The effects of soil water spatial variability previous to irrigation and of the field capacity on the estimation of irrigation water depth are evaluated. The experiment consisted of a common bean (Phaseolus vulgaris L.) crop established on a Kandiudalfic Eutrudox of Piracicaba, SP, Brazil, irrigated by central pivot, in which soil water contents were evaluated with a depth neutron gauge, in a grid of 20x4 points with lag of 0.5 m. In a given situation, the 80 calculated irrigation water depths presented a coefficient of variation of 29.3%, with an average water value of 18 mm, maximum of 41mm and minimum of 9 mm. It is concluded that the only practical way of irrigation is the use of an average water depth, due to the inherent variability of the soil, and that the search for better field capacity values does not imply in better water depth estimates.

Vegetation changes in shallow marsh wetlands under improving moisture regime

1973 ◽  
Vol 51 (8) ◽  
pp. 1443-1457 ◽  
Author(s):  
J. B. Millar
Keyword(s):  
Species Composition ◽  
Water Depth ◽  
Plant Cover ◽  
Open Water ◽  
Growing Season ◽  
Vegetation Changes ◽  
Moisture Regime ◽  
Complete Elimination ◽  
Normal Water ◽  
Emergent Species

Changes in species composition and plant cover were studied in relation to moisture regime over a 10-year period in 71 shallow marsh wetlands in the grassland and parkland regions of Saskatchewan. Decreases in density of the shallow marsh emergents Polygonum coccineum, Carex atherodes, Scolochloa festucacea, and Eleocliaris palustris occurred with greater-than-normal water depth at the start of the growing season but 2 or more years of continuous flooding were required to eliminate emergent cover completely and convert the wetland to open water. Repeated autumn reflooding also resulted in complete elimination of emergent species. Changes in species composition occurred when basins were grazed and as vegetation reestablished after cultivation but no changes followed mowing or burning. Alopecurus aequalis, Beckmannia syzigachne, Glyceria grandis, and G. pulchella are designated as "disturbance" species on the basis of their response to soil-exposing events. Presence of small amounts of deep marsh emergents in shallow marsh wetlands is not considered a reliable indicator of wetter moisture regime. Species composition of rooted submergents in a wetland can be used as an indicator of its moisture regime. Shallow marsh wetlands in basins of 1 ac (0.41 ha) or less experienced little year-long flooding and converted to open water only under atypical conditions. Larger wetlands required basin depths in excess of 36 in. (96.4 cm) to have any amount of year-long flooding and to convert to open water. These basin size and depth criteria have applications in habitat evaluation by waterfowl managers.

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