BIOLOGY - Health Scores

Component Level Scores

For each of the five components, their health index scores are combined to create an average overall component health score.

What does the Biology score show?

The combined four biology indices reveal a pattern of lower scores within the Minnesota and Red River basins. The very low Terrestrial Habitat Quality scores appear to be the primary driver of this trend. The overall range statewide is quite narrow particularly when viewing the mean scores.

Biology Component Mean Health Score

Biology Index - Mean Health Score (major scale)

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Creating the Index

Data Inputs

Terrestrial Habitat Quality:

National Land Cover Dataset (NLCD, 2001)
MN County Biological Survey - Biodiversity Significance
Roads (MN DOT, 2010)
National Agricultural Statistic Service (NASS, 2007)

Stream Species Quality:

Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
MN DNR Statewide Mussel Survey Database (MN DNR, 1989-2010)

Species Richness:

Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
Statewide  Mussel Survey Database (MN DNR, 1989-2010)
Breeding Bird Survey (BBS, 1995-2008)

At-Risk Species Richness:

Species of Greatest Conservation Need (MN DNR Wildlife Conservation Strategy 2006)
Indicators of Biotic Integrity Stream Survey Database (PCA, 1996-2006)
MN DNR Statewide  Mussel Survey Database (MN DNR, 1989-2010)
Breeding Bird Survey (BBS, 1995-2008)

Mean biology health rankings

Four biology index values (below) are combined into one mean (average) biology score for each watershed. The overall mean score for Biology reveals statewide trends in system health. Although it may mask any extreme values, it illustrates an overall gradient in results by basin and region. The mean can also be used to compare similar watersheds, such as upstream or downstream within the same basin.  View the mean score together with the index scores to discover how different index values influence the overall mean.   

Biology Index Inputs:

Terrestrial Habitat Quality

Biology Index - Terrestrial Habitat Quality (major scale)

Stream Species Quality

Biology Index - Stream Species Quality (major scale)

Species Richness         

Biology Index - Animal Species Richness (major scale)

At-Risk Species Richness

Biology Index - At Risk Animal Species Richness (major scale)

Index Results

Pattern of results

The mean biology scores generally decrease from north to south and from east to west across Minnesota, although the range of values is quite narrow. The pattern by index is more variable, with the largest range in results in the Terrestrial Habitat Quality index. Very low Terrestrial Habitat Quality scores are predominant throughout the Red River, Minnesota and Lower Mississippi major river basins. Stream Species and Species Richness scores are slightly higher in these same basins. At-Risk Species Richness scores are higher in the St. Croix basin and the southeast blufflands. Northern Minnesota scores are only slightly higher than the other regions of Minnesota, in part due to a low richness of At-Risk Species in those watersheds.

Interpreting results

In many parts of Minnesota, the lack of quality terrestrial habitat is extensive. This lack of habitat may be limiting species distribution and richness as reflected in the other indices.

The Species Richness scores include both terrestrial and aquatic species and show a trend toward higher richness in east central Minnesota. The higher scores reflect the increase in richness related to unique niche habitats found in the St. Croix Basin; as well as the breeding bird survey pattern of increased species counts through central Minnesota.

Conversely, the Minnesota River Basin received very low At-Risk Species Richness scores, following the pattern of very low Terrestrial Habitat Quality scores.

The highest Terrestrial Habitat Quality scores in north central Minnesota also received the highest Stream Species Quality and Species Richness scores.

Next Steps

Future enhancements

Currently, this component does not include data on the health status of Minnesota's many lakes. An aquatic habitat quality index is planned and this may incorporate aquatic lake IBI (index of biotic integrity) data as well as other habitat parameters. This work will be coordinated with a planned update to the terrestrial habitat quality model. The habitat model is scheduled to be refined and recalculated with newer land cover data. The refinement will include reducing the negative impact of lakes causing "fragmentation" of terrestrial habitat in modeling results.

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