Presentation on theme: "Table 2. Vegetative Species List by Site This species list was obtained using the Small Line Transect Method. The plant species at the tip of the right."— Presentation transcript:
Table 2. Vegetative Species List by Site This species list was obtained using the Small Line Transect Method. The plant species at the tip of the right toe was noted 0, 10, and 20 Thinking beyond the bluestem A Glance at how Range and Grassland Condition are Impacting our Prairie Streams INTRODUCTION Land use and land cover in watersheds can have an effect on both the water quality and diversity of biota in the streams which drain the watershed landscape. Grazing is a common land use in the Great Plains, within which exists a broad spectrum for both the intensity of grazing and management of grazed lands. Controlled and light to moderate grazing systems are used to sustain plant diversity and the overall health of the watershed, but heavy use and overgrazing can result in patches of bare ground and altered vegetative structure which increase runoff of surface sediment in streams. Livestock can also directly affect stream bank stability by walking along stream banks and compacting soils or tearing through the banks. The resulting bank destabilization and sedimentation have been shown to impact macroinvertebrate communities through decrease in frequency of taxa (Braccia and Voshell 2006), changes in community composition (Scrimgeour and Kendall 2003), and changes in species traits (e.g. reproductive barriers) of macroinvertebrates (Doledec et al. 2006). Thus, we expect increased intensity of grazing to alter vegetative structure and decrease vegetative diversity and cover, to increase sediment in streams, and decrease the diversity of stream biota. We combine aquatic ecology (which measures the response of stream water quality and biodiversity) and range ecology (measuring direct range condition) to explore the connection between stream biological assessment and range analysis in determining a direct effect of grazing pressure on stream health. Goc, C., J. Wimmer, L. Rech, and B. Hayford, Wayne State College METHODS: Stream data were collected following methods modified from the EPA Rapid Bioassessment Protocol (Barbour et al. 1999) as modified below. Macroinvertebrates: The specimens were collected from Dawes County using a D-frame net along the same thirty meter reach. Macroinvertebrates were loosened from the substrata by walking up the stream and with a garden claw and forcefully scrapping the sides and bottoms of substrates such as cobble, rocks, logs, and leaf litter. The insects were collected with the D-frame net downstream from the disturbance, catching the matter that became loose drifted downstream. Twenty D-net collections were made along the reach. When collection was complete, macroinvertebrates were placed in a pan containing water, were counted to 100, and transferred to a jar containing 80% ethanol and labeled by site. Stream Quality: Water quality was measured by submerging a probe into a relatively calm place near the middle of the stream. The probe recorded readings for temperature, conductivity, dissolved oxygen, pH, and salinity. The lower end of the transect was examined for the amount of boulders, cobble, gravel, sand, or silt present. A densitometer was used to calculate the amount of canopy cover. Observations of land cover were made in the visible area for forest, shrubs, forbs, grasslands, and other. The data were taken as percentages. Range: The range quality evaluation was conducted by randomly selecting three twenty meter transects which extended perpendicularly from a 30 meter stream length. Samples were taken at 0, 10, and 20 meters from the stream bed in an attempt to measure any gradients which might have resulted from distance from the stream bank. Both a traditional Daubenmire frame and the Small Line Transect Method from the Mongolian herder’s handbook were used in data collection. Variables were chosen to address species composition, vegetation structure, and level of disturbance. The Daubenmire frame consisted of one square meter, randomly tossed. Percent bare ground, ratio of forbs to grasses, number of cow pies, and number of hoofmarks found within the frame were recorded. The height of the closest grass and the closest forb to the lower left corner was recorded in centimenters. Vegetation density was recorded using a Roebel pole: the lowest visible decameter from 1 meter off the ground 5 paces from the pole was recorded. One Roebel measurement was taken from each direction and the four were averaged for final analysis. Litter height was also taken near the placement of the Roebel pole. Using the Small Line Transect Method (SLTM) the researcher would record presence or absence of bare ground, cow pies, and hoof marks, as well as plant type (grass, forb, woody shrub or invasive), plant height, plant name (to lowest level possible), and soil temperature found at the tip of his right toe at each stopping point. Analytical: Descriptive statistics were calculated and normality texts were conducted to determine whether variables met assumptions of normality before inclusion in the correlation analysis. Spearkman- rank correlation was performed with significance set at either P< 0.05 or Descriptive statistics were calculated using MS Excel and normality tests and spearman-rank correlation was performed using Number Crunching Statistical Software. SITE SELECTION Sites chosen for this study consisted of those previously used in other studies of streams in the Nebraska Pine Ridge region, including one site from Chadron State College’s P3 Project in the Pine Ridge area because previous analysis of these sites was available for calibration of methods. Sites studied ranged from heavily grazed to rested for several years. Nine different sites were evaluated in this area. Future sites to be evaluated are located in and around Wayne County in northeast Nebraska. Water Quality The mean conductivity was 0.39 with the highest conductivity 0.57 at Lower Trunk Butte Creek and the lowest 0.29 at Upper White River. Mean dissolved oxygen levels were 4.1 ppm with the highest levels at White River with 8.78 ppm and lowest at CCWMA with 1.9 ppm. Silt and cobble had a negative correlation at -0.89%. Forb LDB, mean litter height, and mean ratio of forbs to grass all correlated positively to gravel in the stream. Grassland and shrubs correlated negatively with forbs WS while grassland LDB and mean litter height correlated positively to forb WS. The mean ratio of forbs to grass correlated positively with forbs WS at 0.67%. Shrub LDB correlated positively with Grassland WS at 0.86%, mean litter height correlated negatively at -0.78%. Shrub RDG and Forb LDB correlated positively at 0.69%. Shrub LDB also correlated positively with shrub RDG at 0.71%. Forb LDB had positive correlations with mean height of forbs and mean roebel height. Grassland LDB also correlated positively with mean litter height at 0.75%. Mean height of grass had a positive correlation with mean Roebel at 0.97%. Mean litter height had a negative correlation with the mean ratio of forbs to grass at -0.69%. Table 1. Range Data with Significant Correlation to Conductivity Of the 13 quantitative measurements taken, these 6 showed significant or nearly significant correlation at the P<.1 level. (P<.1 was chosen instead of P<.05 as suggested by Peterman that.05 may be too low to detect environmental change when there aren’t many plots or there is high spatial variability. These results show that stream health is quantitatively most relevant to grassland structure (soil temperature being indicative of bare ground). Site Forb height in Immediate Riparian Zone (Daubenmire) Grass Height in Immediate Riparian Zone (Daubenmire) Litter Height in Immediate Riparian Zone (Daubenmire) 10 Meter Soil Temperatu re (SLTM) 20 Meter Soil Temperature (SLTM) Streamside Plant Height (SLTM)Conductivity P Value Unit cm Celsius cm TBL BBC CC-CSP CC-WMA EAC SQ WAC WRL WRU RESULTS Range Poaceae: Green Asteraceae: Red Fabaceae: Blue Other: Black Site ListStreamside10 meters20 meters White River LowerPoa pratensisTrifoliumPoa pratensis FabaceaeTrifoliumVerbascum thapsus FabaceaePoa pratensisPoaceae Squaw CreekPoa pratensisBromus inermis Lygodesmia junceaBromus inermis Poa pratensisBromus inermis West Ash CreekCalamovilfa longifoliaPoaceaePoa pratensis Glycyrrhiza lepidota Calamovilfa longifoliaEquisetum hymaleElytrigia intermedia East Ash CreekCarexPoa pratensisSheperdia CarexPoa pratensisAmbrosia Spartina pectinataAmbrosiaSheperdia White River UpperSpartina pectinataArtemisia absinthum CarexArtemisia absinthum CarexPoa pratensisArtemisia absinthum Trunk Butte Creek LowerBromus tectorumMelilotusPoa pratensis BrassicaceaeElytrigia intermedia Bromus inermisElytrigia intermediaBromus tectorum Chadron Creek WMAPoa pratensis Poaceae Poa pratensisElytrigia intermediaBrassicaceae Poa pratensis Rumex crispus Chadron Creek Chadron State ParkSpartina pectinataPoa pratensis Bromus inermisPoa pratensisTrifolium Big Bordeaux CreekCirsiumBromus inermis Poa pratensis Sheperdia Poa pratensis meters from the stream in an attempt to establish a species gradient with distance from streams. Sites with high occurrence of Poa or Bromus tended to have a more intense grazing or disturbance history. Sites (such as White River Upper) with a high composition of Artemisia absinthum tended to be under high current grazing pressure. Sites with a greater diversity of species seemed had seen either less grazing intensity or more intensive management. These results lead us to believe that site history may be correlated species composition. Future research will explore this question further. Macroinvertebrates The highest numbers of macroinvertebrate fauna fall under Ephemeroptera, Trichoptera, Diptera and Coleoptera. Trichopterans leading the way at every site except for Big Bordeaux Creek. Table 3. Partial list of macroinvertebrate taxa identified from the study sites in the Pine Ridge, NE. Common nameTaxonChadron CreekBig BordeauxSquaw CreekWhite RiverTrunk ButteEast Ash CreekWest Ash CreekTotal FlatwormsTricladida Aquatic wormsOligochaeta LeechesRhynchobdellida SnailsBasommatophora Fingernail clamsVeneroida ScudsAmphipoda DragonfliesOdonata StonefliesPlecoptera True bugsHemiptera MayfliesEphemeroptera CaddisfliesTrichoptera FliesDiptera BeetlesColeoptera Total611 By far the three most common taxa based on number collected are Ephemeroptera, Trichoptera, and Diptera. This shows at first glance that the sites were relatively low in disturbance because the Ephemeroptera and Trichoptera taxa collected tend to be sensitive to high disturbance of their habitat. The Diptera taxa represent the influence of spring flow in their habitat as Diptera dominate in spring fed aquatic habitat. Table 3. Spearman rank correlation of percent estimate habitat values and direct measurement values for stream sites in the Pine Ridge of Nebraska. These variables are those which were sampled and which met the assumptions of normality. Thus, they are a subset of all the variables estimated and measured. COBBGRVLSILTFORWSSHRBWSFRBSWSGRSSWSFORLDB SHRBLD BFRBSLDBGRSSLDBFORRDB SHRBRD G FRBSRD B GRSSRD BMNHOFMNHOG MNROE BMNLHMNRFG COBB 1.00 GRVL SILT FORWS SHRBWS FRBSWS GRSSWS FORLDB SHRBLDB FRBSLDB GRSSLDB FORRDB SHRBRDG FRBSRDB GRSSRDB MNHOF* MNHOG MNROEB MNLH MNRFG significant correlations at p < 0.05 Table XX. Descriptive statistics for water quality and habitat variables from stream study sites in the Pine Ridge of Nebraska. Habitat values are based on estimates made following methods modified from the U.S. EPA Rapid Bioassessment Protocol (Barbour et al. 1999). Range Code*MeanMedianMinMaxStDev. Water temp deg CNA Conductivity mS/cm DO ppm pH Salinity ppm Boulder > 256mm Cobble mm (COBB)* Gravel 2-64 mm (GRVL) Sand.06-2 mm Silt mm (SILT) % Riffle % Run % Pool Run Width Densiometer Land cover in the visible watershed % Forest (FORWS) % Shrubs (SHRBWS) % Forbs (FRBSWS) % Grasslands (GRSSWS) % Other0.00 Land use in the visible watershed % Grazing % Town0.00 % Ger0.00 % Mining0.00 % Natural % Other0.00 Land use/cover in the left descending bank % Forest (FORLDB) % Shrubs (SHRBLDB) % Forbs (FRBSLDB) % Grasslands (GRSSLDB) % Other Land use/cover in the right descending bank % Forest (FORRDB) % Shrubs (SHRBRDB) % Forbs (FRBSRDB) % Grasslands (GRSSRDB) % Other * Letters in capitals are the code used in the correlation analysis. * Range variable codes: MNHOF=Mean Height of Forbs MNHOG=Mean Height of Grass MNROEB=Mean Roebel MNLH=Mean Litter Height MNRFG=Mean Ratio Forbs to Grass DISCUSSION This project achieved its goals in producing a protocol by which to directly measure range condition along streams. Many of the percent estimate data were correlated to the directly measured range condition data. Range data showed that grazing related variables which affected stream quality were mainly those related to vegetative structure. Plant species composition was also impacted. Most sites were not currently being grazed at the time of sampling, but those that were (White River) did have lower numbers of disturbance sensitive macroinvertebrates. This evidence points to the conclusion that heavy grazing affects vegetative structure, which in turn affects stream sedimentation, which influences the macroinvertebrate community structure. Range Protocols and Future Directions Range evaluation protocols are traditionally used to evaluate a piece of land’s suitability or tolerance to different intensities of grazing, its health or level of integrity, or its value as habitat for certain grassland dependent species. Using this research to pinpoint which variables are directly correlated to stream health, we will attempt to create a protocol which evaluates grassland health in relation to its prairie ecosystem. This protocol ideally will be tailored to pinpoint which factors in any specific grassland are directly relevant to the health of its dependent streams. With further research we feel it could be possible to streamline this protocol for quick and easy use not only by science professionals but also the landowners who are directly dependent on these ecosystems. Future research extensions include a substantial increase in study sites from our current nine to an ambitious minimum of thirty with a focus on including a broader range of health and disturbance within study sites. Future protocols may include a more comprehensive look at species diversity as well as a ratio of native to non-natives. Because stream recovery rates are largely unknown digging deeper into site histories may provide valuable insights. Finally, a remote sensing project which maps out land use in the study area will attempt to take into account upstream influences. ACKNOWLEDGEMENTS We would like to thank the Wayne State College and the National Science Foundation for f equipment and funding to make this project possible. We would also like to thank the landowners in the Pine Ridge area who allowed us to access their land for this project. Figure 1. (Above) Measuring out the stream length along a less impacted site. Figure 2. (Below) Upper White River. An example of a heavily grazed site. Figure 3. Student research crew. Research Goals This project had the following goals: 1.To create a tool by which to directly measure range condition along streams. 2.To determine whether percent estimate watershed and riparian range data were correlated with directly measured range conditions data.