I have two data sets that may be used to make predictions regarding wetlandvegetation changes in Lake Michigan-Huron in response to different regulationplans during low supply periods when lake levels fall after highs.

Example years include: 1909-1911, 1918-1926, 1929-1937, 1952-1959,1960-1964, 1974-1978, 1986-1992,1997-2006

73.5

74.0

74.5

75.0

75.5

76.0

1860

1870

1880

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

Lake

Lev

el

(met

ers,

IGLD

198

5)

Lake Michigan-Huron

Six years of elevation-specific data from Fish Point wetland in Saginaw Bay of Lake Huron

500m-long transects 1-6 follow contours at elevations of 176.3, 176.55, 176.65, 176.9, 177.24, and 177.34 m IGLD1985

Distance between transects, creating 220-500m1-2 = 180m topo/bath platform2-3 = 10m3-4 = 25m4-5 = 10m5-6 = 5m

Figure 2. Map of Fish Point wetland study area in Saginaw Bay of Lake Huron, Michigan, USA showing approximate placement of seven sampling transects that follow elevation contours.

Plant communities characterized across years by NMDS ordination show distinct groupings of transects/year that reflect response of vegetationto hydrologic history of transects and elevation above water level in the year sampled.

Model derived demonstrating these relationships.

Wilcox and Nichols. 2008. Wetlands 28:487-501

These relationships might be used to predict the percentage of wetland in each vegetationtype based on the 220-500m geometric modeland the portions of the wetland that fall into specific time-dewatered and elevation classes.

Comparisons would be made in responses to different regulation plans.

for any given year: ∑ X1 …+… X7 = 100

X1 = % wetland under water Veg Type I

X2 = % wetland first year dewatered Veg Type II

X3 = % wetland dewatered 1 yr [1-15cm] Veg Type III

X4 = % wetland dewatered 1 yr [16-40 cm] Veg Type IV or 2 yr [10-40 cm]

X5 = % wetland dewatered 2 yr [41-80 cm] Veg Type V or 3 yr [35-70 cm] or 4 yr [30-65 cm] or 5 yr [25-50 cm]

X6 = % wetland dewatered 3 yr [71+ cm] Veg Type VI or 4 yr [66+ cm] or 5 yr [51+ cm] or 6 yr [40+ cm]

X7 = % wetland not flooded Veg Type VII

transect:year

Veg Type I 1:88, 2:88

Veg Type II 2:89, 3:88

Veg Type III 3:89

Veg Type IV 2:90, 2:90, 4:88, 4:89

Veg Type V 4:90, 4:91, 4:92, 5:88, 5:89

Veg Type VI 5:90, 5:91, 5:92, 5:93

Veg Type VII 6:88, 6:89, 6:90

dominants

Veg Type I N. flexilis, N. marina, Chara, M. sibiricum

Veg Type II Chara, N. flexilis, P. gramineus, H. dubia

Veg Type III Chara, P. gramineus, N. flexilis, S. tabernaemontani

Veg Type IV Chara, S. pungens, T. angustifolia, S. tabernae.

Veg Type V S. pungens, E. perfoliatum, T. ang., C. canadensis

Veg Type VI E. graminifolia, C. canadensis, S. exigua, S.pungens

Veg Type VII I. capensis, T. angustifolia, C. canadensis, E. perfol.