Wetlands measure the percent change in wetlands, which are essential for healthy freshwater ecosystems. Unfortunately, a huge number of wetlands have been lost since European settlement and these essential ecosystems continue to decline in Michigan, despite efforts to restore and create new ones (MI wetlands). Protecting remaining wetlands is critical for watershed sustainability. This indicator assesses the percent change in wetland area from 2016–2019.
How is it scored?
The percent difference in wetland area between 2016 and 2019 was calculated. Percent change was converted to the report card scale using the equation, y = 20x + 50, with a loss 2.5% scored a 0 and a gain of 2.5% scored a 100 (Table 1). Scores were capped at 0 or 100. Watershed scores were area-weighted to calculate an overall region score.
Table 1. Scoring thresholds used for the wetland loss indicator. The equation to convert % change to a report card score was, y = 20x + 50.
% Wetland Change | Score | Letter Grade |
-2.5 to -1.5 | 0–20 | F |
-1.5 to -0.5 | 20–40 | D |
-0..5 to 0.5 | 40–60 | C |
0.5 to 1.5 | 60–80 | B |
1.5 to 2.5 | 80–100 | A |
Data source: (MRLC NLCD EVA Tool) https://www.mrlc.gov/eva/.