Northern Great Plains Riverine Analysis 2013 Contents Overview 3 Aquatic Ecosystem Classification 3 Fish Species Richness 8 Ecological Condition Index 8 Analysis 9 Results 9 References 11 Appendix: Individual AES Types 13 2 analysis was not sufficient for evaluating the status Overview of aquatic systems; thus, the terrestrial analysis was Grasslands around the globe are among the least pro- complemented with this independent riverine analy- tected biomes, yet they provide important habitat for sis of the ecoregion. a diversity of species, as well as food, fuel, and fiber We were fortunate to discover that an in-depth, scien- to sustain human populations. The Northern Great tific study was completed for the Missouri River Ba- Plains ecoregion was chosen as one of World Wild- sin in 2010: A GAP Analysis for Riverine Ecosystems life Fund’s (WWF) 15 priority landscapes around the of the Missouri River Basin (Annis et al.). The study world due to its relative intactness, rich biodiversity, area of the GAP project covers nearly all of the U.S. and potential for conservation. portion of the Northern Great Plains Ecoregion (Fig- In 2004, WWF and partners published an assessment ure 1). Thus, we elected to use habitat and threats data of conservation opportunities in the Northern Great from the already-completed project instead of start- Plains ecoregion, entitled Ocean of Grass, which ing anew. Because the species distribution data used has guided the work of many organizations over the in the GAP analysis was non-shareable, we comple- past decade. However, the landscape has changed in mented the data with distribution data for 16 species many ways since data were gathered for the previous derived from a combination of NatureServe G1-G3 assessment. In 2012, we reassessed the ecoregion, listed species, endemic, keystone and focal species collecting up-to-date information on wildlife distri- (as listed in Forrest et al. [2004] and TNC [1999]; bution, geography, demographics, climate change, focal species identified by senior-level WWF staff). and threats. We identified “priority” areas within the Following Heiner et al. [2010] and Higgins (pers. ecoregion based on species richness and intact habi- comm.), we defined an analysis that would identify tat. However, we recognized that a terrestrial-based riverine conservation priority areas based on repre- sentation (species and habitat richness) and ecologi- cal condition (derived from Human Threats Index). If, in the future we choose to select a limited number of sites, we can incorporate additional criteria, con- nectivity and efficiency, to select the most opportu- nistic and effective areas to apply our resources. Aquatic Ecosystem Classification The GAP project used a hierarchical classification to delineate the Missouri River Basin into nested levels (as described below and in Table 1). The Northern Great Plains (NGP) portion of the Mis- souri River Basin is contained in one Zone - Nearc- tic, one Subzone - Arctic/Atlantic, and one Region - Mississippi. Within the NGP, there are eight Aquatic Subregions (Figure 2), 22 Ecological Drainage Units (Figure 3), and 24 Aquatic Ecological System Types (Figure 4). Figure 1. Missouri River Basin study area in comparison to the Northern Great Plains Ecoregion. 3 Table 1. Hierarchical framework for classifying the Missouri River Basin in the aquatic GAP project. Table from Sowa et al. [2007]. Defining Physical Defining Biological Level Description Features Features Six major zoogeographic zones of Continental boundaries Family-level patterns the world that resulted from distinct Global climate Endemism Zones evolutionary histories associated with plate tectonics Subcontinental zoogeographic strata Major river networks and Family-level patterns with relatively unique aquatic assem- basin boundaries Endemism Subzones blages created in large part by plate Regional climate tectonics, glaciation, and mountain building Subzone zoogeographic strata cre- Major river networks and Family- and species- ated in large part by drainage network basin boundaries level patterns patterns that determine dispersal Regional climate Endemism Regions routes and isolation mechanisms that Phylogenetics have resulted in different responses to long-term changes in climate Region stratification units. Large Regional climate Family- and species- areas of similar climate and physiog- Physiography level patterns raphy that often correspond to broad- General physiognomy of Endemism scale patterns in dominant vegetation vegetation Distinct foraging, repro- Aquatic Subregions ductive, and habitat-use guilds Distinct physiological tolerances Subregion zoogeographic strata. Ag- Drainage boundaries Family- and species- Ecological Drainage gregates of subdrainages with similar Physiography level patterns Units physiographic character and a com- Endemism mon evolutionary history. Phylogenetics Hydrogeomorphic subunits of Eco- Watershed boundaries Species-level patterns logical Drainage Units. Hydrologic Position within larger Distinct foraging, repro- units with similar physiographic drainage ductive, and habitat-use Aquatic Ecological character, basin morphometry, and Local and watershed guilds System Types position within the larger drainage. physiography Distinct physiological Represent ecological neighborhoods; Local climate tolerances each type contains similar combina- Basin morphometry tions of valley segment types. Hydrogeomorphic subunits of Aquatic Temperature Species-level patterns Ecological Systems. Aggregates of Stream size Distinct foraging, repro- stream reaches with broad similarities Permanence of flow ductive and habitat-use Valley Segment Types in fluvial processes, sediment trans- Position within drainage guilds port, riparian vegetation, and thermal network Distinct physiological regime. Valley geomorphology tolerances Hydrogeomorphic subunits of Valley Depth Species-level patterns Segment Types (e.g., riffle, pool, run). Velocity Distinct foraging, repro- Substrate ductive and habitat-use Habitat Unit Types Position within the chan- guilds nel Physical forming fea- tures 4 Figure 2. Aquatic subregions of the Northern Great Plains Ecoregion as delineated by Annis et al. [2010]. 5 Figure 3. Ecological drainage units of the Northern Great Plains Ecoregion as delineated by Annis et al. [2010]. 6 # Name 1 Jefferson River 2 Deep Creek 3 Belle Fourche River 4 Middle Yellowstone River 5 Sunlight Creek 6 Sun River 7 Clarks Fork Yellowstone River 8 Sage Creek 9 Horse Creek 10 Branch Knife River 11 Upper Republican River 12 Tongue River 13 Loup River 14 Rose Creek 15 Lower North Platte River 16 Laramie River 17 Smoky Hill River 18 Gooseberry Creek 19 West Plum Creek 20 Lower Musselshell River 21 Cannonball River 22 Lower Little White River 23 Missouri River 24 Choteau Creek Figure 4. Aquatic ecological system types of the Northern Great Plains Ecoregion as delineated by Annis et al. [2010]. Note: Each Aquatic ecological system may have multiple polygons (shown in the same color), however only the largest unit of each type is numbered. 7 Fish Species Richness Following the procedure for calculating terrestri- al species richness in the Ocean of Grass analysis [2012], we selected fish species from a combina- tion of NatureServe G1-G3 listed species, endemic, keystone and focal species (as listed in Forrest et al. [2004] and TNC [1999]; focal species identified by senior-level WWF staff). A total of 16 species were identified (Table 2). We combined current distribu- tion data (NatureServe 2010) for all species into one 1° grid of Species Richness (Figure 5). Distribution data was only available for the U.S. portion of the ecoregion, thus our current analysis is restricted to the United States. Table 2. List of species used to create Fish Species Richness layer. Common Name Scientific Name Lake sturgeon Acipenser fulvescens 7.5 Northern redbelly dace Chrosomus eos Brook stickleback Culaea inconstans Blue sucker Cycleptus elongates Iowa darter Etheostoma exile Figure 5. Fish Species Richness Index for the Northern Great Western silvery minnow Hybognathus argyritis Plains Ecoregion. Brassy minnow Hybognathus hankinsoni Plains minnow Hybognathus placitus Sturgeon chub Macrhybopsis gelida Sicklefin chub Macrhybopsis meeki Northern pearl dace Margariscus nachtriebi Hornyhead chub Nocomis biguttatus Fathead minnow Pimephales promelas Flathead chub Platygobio gracilis Paddlefish Polyodon spathula Pallid sturgeon Scaphirhynchus albus Ecological Condition Index A Human Threats to Ecological Integrity Index was developed as part of the Missouri River Basin GAP project in an attempt to quantify relevant threats to aquatic systems (Table 3, Annis et al. 2010). We up- dated the layer with more recent data for Cropland, Pasture, Impervious Surface, and Population Change 19.5 because of significant changes from the data used in the GAP analysis (Table 3). In our analysis, we used the threats index as a measure of ecological condi- tion, i.e. the area with a low threat score likely had Figure 6. Ecological Condition Index for the Northern Great higher ecological integrity than area with high threat. Plains Ecoregion. 8 Within the entire Missouri River Basin, ecological condition ranged from 12 (good) to 32 (poor). In the Analysis NGP (updated index), ecological condition ranged We rescaled the Fish Species Richness Index and from 10 (good) to 29 (poor, Figure 6). Ecological Condition Index using linear interpolation Table 3. Components used to create the Human Threat Index to, respectively,