Palouse Research Articles

When the prairie varies: the importance of site characteristics for strategising insect conservation

Abstract. 1. The bunchgrass prairies of the Palouse region in eastern Washington state and adjacent Idaho have been mostly converted to agriculture in the past century. Prairie habitat currently exists only on small remnants scattered across the landscape.2. The invertebrate fauna of these habitat remnants is poorly known, both in terms of species diversity and community composition.3. Baited pitfall traps were used to sample carrion‐attracted beetles during June and July of 2003 from high‐quality prairie remnants of varying size and soil characteristics.4. Twenty‐three beetle species in five families were found. Species richness and Shannon‐Wiener diversity were not significantly correlated with habitat area or perimeter–area ratio.5. Beetle abundance and community structure were strongly correlated with soil characteristics. Deeper, loessal soils had greater overall beetle abundance than shallower, rocky soils, although some species were more frequently captured in shallower, rocky soil sites.6. Conservation plans emphasising only remnant size and condition do not sufficiently capture variability in insect communities across Palouse prairie remnants.

Plowed Under: Agriculture and Environment in the Palouse

Plowed Under: Agriculture and Environment in the Palouse

Influence of Soil and Site Characteristics on Palouse Prairie Plant Communities

The structure of grassland communities can vary widely in response to heterogeneous habitat variables. In this study we document plant communities, soil types, and site characteristics for 12 Palouse prairie remnants in southeastern Washington and northern Idaho. We used general linear models to test the predictive value of 6 biophysical variables (slope, aspect, distance from edge, edge type, vegetation structure, and soil type) on 3 plant community metrics: species richness, Simpson's diversity index, and the dominance of exotic species. From full models including all variables, we used Akaike's information criterion (AIC) to select the best model for each metric. Aspect and vegetation structure were significant predictors of species richness (R2 = 0.08) and diversity (R2 = 0.09), while aspect, soil type, distance from edge, and edge type (type of adjacent matrix habitat) influenced the dominance of exotic species (R2 = 0.28). Additional soil sampling determined that the depth to a restrictive layer also had significant impacts on the dominance of exotic species (R2 = 0.31). This study confirms that biophysical characteristics influence Palouse prairie plant communities and may help set research and conservation priorities for isolated and uninventoried remnants.

Plowed under: agriculture & environment in the Palouse

Plowed under: agriculture & environment in the Palouse

Myrmecochory of the Exotic Plant,Centaurea maculosa: A Potential Mechanism Enhancing Invasiveness

Abstract We hypothesized that the elaiosomes of seeds of the invasive plant, Centaurea maculosa (spotted knapweed), elicit seed-dispersing behavior by native ants (myrmecochory), potentially providing a mechanism enhancing its invasiveness into native plant communities. Elaiosomes are small nutrient-rich nodes produced on seeds of some plants. Ants collect and disperse elaiosome-bearing seeds, later consuming the elaiosome, but usually discarding the seed intact away from the parent plant. The seeds of C. maculosa possess elaiosomes, suggesting that the dispersal of its seeds and its ability to rapidly spread into native habitats may be enhanced by myrmecochory. We tested for myrmecochory at two Palouse prairie sites in Montana by presenting seeds of C. maculosa and two native dominants, Balsamorhiza sagittata (a forb) and Psuedoroegneria spicata (a bunchgrass). Seeds were presented in choice (seeds of all three plants) and no choice (seeds of only one plant) treatments. At both study sites, ants readily ...

Southwick Soil of the Idaho Palouse

Southwick Soil of the Idaho Palouse

Wildfire-resistant biological soil crusts and fire-induced loss of soil stability in Palouse prairies, USA

Frequent low-intensity fires are a natural component of the ecology of the Palouse prairies of northwestern North America. To study the effects of fire upon biological soil crusts (BSCs) occurring in these grasslands, we sampled three burned (in 2000) sites and three unburned sites in the Hell’s Canyon area (OR, USA) ∼1 year post-fire. We measured vascular plant and BSC cover, soil microbe pigmentation, texture and chemistry, and soil surface physical properties (stability and rugosity). Festuca idahoensis was two times more abundant in unburned plots ( P=0.0006), and vascular plant and litter cover were generally higher in unburned plots. At the community scale, there was no difference in the lichen and moss species composition, suggesting much less drastic effects of fire on BSCs than reported in other systems. Soil surface stability (measured using slake value) was significantly lower in burned sites than unburned sites (median value=5 versus 6, P=0.008), a result which is likely due to the greater density of lichens and mosses encountered in the unburned plots. Soil microbe pigmentation was lower in burned plots ( P=0.03), suggesting that the biomass of photosynthetic microbes had decreased; however, the presence of intra- and extracellular pigments in burned soils indicates that microorganisms were not eradicated. Pigments most strongly associated with cyanobacteria were more abundant in unburned sites, suggesting that cyanobacteria may have been more strongly impacted by the fire than other BSC components. Composition of nutrients and surface rugosity did not differ significantly between treatments. We hypothesize that Palouse prairie soil crusts are relatively resistant to wildfire because of low fire intensity and their occupation of space away from the vascular plant fuel load.

Effects of Water Quality on Cattle Performance

Water is an important nutrient for livestock production and is often provided on rangelands directly from ponds or dugouts. Cattle may defecate and urinate into the water thereby adding nutrients and reducing palatability. A study was conducted to examine the effects of water source on cattle production and behavior, to determine the relationship of selected chemical and biological constituents on the observed response and to test the effect of fecal contamination on water consumption. Four dugouts or ponds were selected at 4 sites: 2 in the Fescue Prairie near Stavely in southwestern Alberta, 1 in the Mixed Prairie at Onefour in southeastern Alberta, and 1 in the Palouse Prairie near Kamloops, British Columbia. Yearling Herefords were tested at 3 sites and Hereford cow-calf pairs at 1 Stavely site. At each site, three paddocks radiated from the pond that were stocked with 10 yearlings or cow-calf pairs randomly assigned to either clean water (water delivered to a trough from a well, river, or pond), pond water pumped to a trough (pondtrough), or direct access into the pond (ponddirect). The trials were repeated at each site for 3 to 6 years. Observations were made on cattle weight gains, cow backfat thickness, and activity budgets. Fecal samples were analyzed for selected parasites and pathogens. Other experiments were conducted to determine the effects of manure-contaminated water on feed and water consumption and water selection. Calves, with cows drinking clean water, gained 9% more ( P < 0.10) weight than those with cows on ponddirect but cow weight and backfat thickness were not affected. Yearling heifers having access to clean water gained 23% (P = 0.045) and 20% (P = 0.076) more weight than those on ponddirect and pondtrough, respectively. Cattle avoided water that was contaminated with 0.005% fresh manure by weight when given a choice of clean water. Cattle that had access to clean water spent more time grazing and less time resting than those that were offered pond trough or pond direct . Cattle management must consider water quality together with forage conditions in order to achieve optimal production from rangeland.

Perennial Wheat Germ Plasm Lines Resistant to Eyespot, Cephalosporium Stripe, and Wheat Streak Mosaic.

A perennial wheat cropping system on the Palouse Prairie of eastern Washington may provide an alternative to the Federal Conservation Reserve Program and reduce soil erosion while providing a harvestable crop for growers. Twenty-four perennial wheat germ plasm lines resulting from crosses between wheat and wheatgrass were evaluated under controlled environment conditions for resistance to Wheat streak mosaic virus (WSMV), Cephalosporium gramineum, and Tapesia yallundae (anamorph Pseudocercosporella herpotrichoides var. herpotrichoides). Perennial wheat lines SS452, SS103, SS237, MT-2, and PI 550713 were resistant to all three pathogens. Eight lines (33%) were resistant to WSMV at 21°C and 25°C; AT3425 was resistant to WSMV at 21°C but not at 25°C. Thirteen lines (54%) were highly to moderately resistant to C. gramineum. Thirteen lines (54%) were resistant to T. yallundae in each experiment, but the reactions of four lines differed between experiments. The wheatgrasses Thinopyrum intermedium (PI 264770) and Thinopyrum ponticum (PI 206624) are reported as new sources of resistance to T. yallundae. Perennial wheat must have resistance to these diseases in order to be feasible as a crop in the Pacific Northwest.

Effects of water quality on cattle performance

Water is an important nutrient for livestock production and is often provided on rangelands directly from ponds or dugouts. Cattle may defecate and urinate into the water thereby adding nutrients and reducing palatability. A study was conducted to examine the effects of water source on cattle production and behavior, to determine the relationship of selected chemical and biological constituents on the observed response and to test the effect of fecal contamination on water consumption. Four dugouts or ponds were selected at 4 sites: 2 in the Fescue Prairie near Stavely in southwestern Alberta, 1 in the Mixed Prairie at Onefour in southeastern Alberta, and 1 in the Palouse Prairie near Kamloops, British Columbia. Yearling Herefords were tested at 3 sites and Hereford cow-calf pairs at 1 Stavely site. At each site, three paddocks radiated from the pond that were stocked with 10 yearlings or cow-calf pairs randomly assigned to either clean water (water delivered to a trough from a well, river, or pond), pond water pumped to a trough (pond(trough)), or direct access into the pond (pond(direct)). The trials were repeated at each site for 3 to 6 years. Observations were made on cattle weight gains, cow backfat thickness, and activity budgets. Fecal samples were analyzed for selected parasites and pathogens. Other experiments were conducted to determine the effects of manure-contaminated water on feed and water consumption and water selection. Calves, with cows drinking clean water, gained 9% more (P &lt; 0.10) weight than those with cows on pond(direct) but cow weight and backfat thickness were not affected. Yearling heifers having access to clean water gained 23% (P = 0.045) and 20% (P = 0.076) more weight than those on pond(direct) and pond(trough), respectively. Cattle avoided water that was contaminated with 0.005% fresh manure by weight when given a choice of clean water. Cattle that had access to clean water spent more time grazing and less time resting than those that were offered pond(trough) or pond(direct). Cattle management must consider water quality together with forage conditions in order to achieve optimal production from rangeland.

Identification of Regional Soil Quality Factors and Indicators II. Northern Mississippi Loess Hills and Palouse Prairie

Diversity of soil series present in a region may hinder identification of soil quality factors and indicators at a regional scale. Our objectives were (i) to identify soil quality factors for a diverse population of soils at the regional scale, (ii) to determine which factors vary significantly with land use, (iii) to select indicators from these factors that can be used with the National Resource Inventory (NRI) for monitoring soil quality, and (iv) to compare these results to a similar study involving only a single soil series. One hundred eighty‐six points representing 75 soil series in the Northern Mississippi Valley Loess Hills and 149 points representing 58 soil series in Palouse and Nez Perce Prairies were sampled from a statistically representative subset of NRI sample points and analyzed for 20 soil attributes. Factor analysis was used to identify soil quality factors and discriminant analysis was used to identify factors and indicators most sensitive to land use within each region. In the Northern Mississippi Valley Loess Hills, five soil quality factors were identified. Discriminant analysis selected potentially mineralizable N (PMN), microbial biomass C (MBC), water stable aggregates (WSA), and total organic C (TOC) as the most discriminating attributes between land uses. In the Palouse and Nez Perce Prairies, six factors were identified. Discriminant analysis selected TOC and total N as the most discriminating attributes between land uses. The soil quality factors were similar among three of the four regions, but TOC was the only indicator common to all regions for distinguishing among land uses.

AN ECOLOGICAL STUDY OF A REGULATED PRAIRIE STREAM IN WESTERN MONTANA

Longitudinal and seasonal changes in biophysical variables were examined in this seminal study of an intermountain (Palouse) prairie stream. Hypolimnial releases from an irrigation reservoir controlled discharge, temperature and other habitat variables, thereby influencing distribution and abundance of zoobenthos. Dramatic changes in turbidity and nutrient concentrations occurred during the spring runoff and summer irrigation periods and following wind-driven sediment resuspension in the reservoir. Seasonal changes in the relative dominance of certain macroinvertebrate taxa were correlated with physical and chemical dynamics. Based on detrended correspondence analysis (DCA), specific conductance, temperature, dissolved oxygen and nitrates + nitrites were the variables most associated with seasonal macroinvertebrate biomass. Changes in taxa composition downstream from the dam were mainly related to species additions from site to site. Changes in pH and substratum were associated with longitudinal changes in biomass. For instance, the observed bimodal distribution of Cheumatopsyche sp. was correlated with percentage boulder substratum among the sites. On the other hand, DCA performed on macroinvertebrate densities emphasized pH, total ammonia, discharge and substratum. Species composition throughout the prairie segment of the stream was very different from that in the mountain canyon segment. The effects of regulation ameliorated significantly in a downstream direction from the dam. Presence of warm water species (e.g. Helicopsyche sp.) upstream and downstream of the reservoir were indicative of the native stream fauna of the intermountain prairies. Faunal responses to the ‘recovery’ gradient downstream from the dam provided a basis for the development of remedial management actions.

Long-Term Population Analysis of Gray Partridge in Eastern Washington

Recent studies reported that gray partridge (Perdix perdix) populations have declined throughout Europe and Asia. Gray partridge on the Palouse Prairie of Washington also have been reported to be in decline. Therefore, we analyzed densities of gray partridge on the Palouse Prairie of Washington to determine long-term population trends (1940-92). We also tested for density dependence in recruitment and fall-and-winter mortality rates and attempted to relate annual variation in recruitment and mortality to weather and habitat variables. Spring and/or fall estimates of density were available for 33 of 53 years and varied from 1.3 to 23.2 birds/km 2 in the spring and from 0.1 to 28.6 birds/km 2 in the fall. The population's return point from 1940 to 1954 was 3.45 birds/km 2 versus 6.72 birds/km 2 from 1982 to 1992, indicating that density was higher in the more recent period. Surprisingly, this result contrasts with a series of reports that indicated that the population was in serious decline. We detected density-dependent effects on recruitment rate, fall-and-winter mortality rate, and annual change in population size. Density dependence had the strongest effects on recruitment rate. Recruitment rate averaged 1.55 (SE = 0.27) but ranged widely (0.38-3.38). Fall-and-winter mortality averaged 0.29 (SE = 0.06). We were not able to explain variation in population-growth rate or fall-and-winter mortality rate using habitat and/or weather variables (P > 0.11). Under current habitat conditions, density typically will be 6.7 birds/km 2 in the spring and 10.4 birds/km 2 in the fall and can be expected to vary markedly independent of density. By combining available datasets, we developed a lengthy time series adequate for investigating long-term population dynamics. Such an approach may be possible and informative for other populations.

Dynamics of two Montana grasshopper populations: relationships among weather, food abundance and intraspecific competition.

The population dynamics of two grasshoppers (Melanoplus femurrubrum and M. sanguinipes) were studied using experimental microcosms over 8 years at a Palouse prairie site in Montana. Grasshopper density, survival and reproduction in the experimental populations responded in a density-dependent fashion to natural and experimental changes in food availability for all grasshopper developmental stages, both within and between all years. We observed that field populations of the grasshoppers at the site exhibited density, survival and reproductive responses similar to the experimental populations over the period of the study. Because we could not identify any differences between the field and microcosm environments or the grasshopper individuals in them, we contend that field populations were ultimately limited by food within and between years. Density-dependent food limitation occurred for all age categories over the entire summer, because food abundance declined relative to grasshopper food requirements over the summer. Food limitation occurred between years, because in years with the lowest food abundance, the populations produced more hatchlings for the next year than could be supported by the highest observed food abundance. Finally, the observed annual changes in food abundance were correlated with the annual variation in weather (rainfall and temperature), which indicated that the long established relationship between grasshopper densities and weather conditions does not imply population limitation by density-independent processes.

Life history variation in blue flax (Linum perenne: Linaceae): seed germination phenology

Linum perenne L. is a nonclonal perennial herb widely distributed across a range of habitats. Variation in seed germination patterns was examined for 21 Intermountain collections and for the commercial cultivar ‘Appar’. Collections from sites with long, snowy winters were largely dormant at harvest and responded positively to chilling. Collections from middle elevation sagebrush‐grassland sites were generally nondormant and contained a fraction induced into secondary dormancy by chilling. Collections from palouse prairie and pinyon‐juniper sites were generally nondormant and unaffected by chilling, as was ‘Appar’. When seeds of contrasting populations were planted in seed retrieval experiments at low, middle, and high elevation sites, their field germination phenology was predictable from laboratory experiments. In common garden experiments, there were significant among‐sibship differences in germination for each garden‐grown wild accession but not for ‘Appar’, suggesting that differences both among and within populations may be genetically based. Garden‐grown seeds were generally less dormant than wild‐collected seeds, possibly because of selection during propagation. Results demonstrated the existence of ecologically relevant among‐population and within‐population variation in germination phenology for blue flax. Seeds of high‐montane populations are spring‐emerging and have little provision for between‐year carryover. Populations from lower elevation habitats with less predictable weather have seeds with contrasting germination patterns, allowing for emergence in both fall and spring as well as for seed bank carryover. ‘Appar’ seeds lack these predictive and carryover mechanisms.

Life History Variation in Blue Flax (Linum perenne: Linaceae): Seed Germination Phenology

Linum perenne L. is a nonclonal perennial herb widely distributed across a range of habitats. Variation in seed germination patterns was examined for 21 Intermountain collections and for the commercial cultivar ‘Appar’. Collections from sites with long, snowy winters were largely dormant at harvest and responded positively to chilling. Collections from middle elevation sagebrush-grassland sites were generally nondormant and contained a fraction induced into secondary dormancy by chilling. Collections from palouse prairie and pinyon-juniper sites were generally nondormant and unaffected by chilling, as was ‘Appar’. When seeds of contrasting populations were planted in seed retrieval experiments at low, middle, and high elevation sites, their field germination phenology was predictable from laboratory experiments. In common garden experiments, there were significant among-sibship differences in germination for each garden-grown wild accession but not for ‘Appar’, suggesting that differences both among and within populations may be genetically based. Garden-grown seeds were generally less dormant than wild-collected seeds, possibly because of selection during propagation. Results demonstrated the existence of ecologically relevant among-population and within-population variation in germination phenology for blue flax. Seeds of high-montane populations are spring-emerging and have little provision for between-year carryover. Populations from lower elevation habitats with less predictable weather have seeds with contrasting germination patterns, allowing for emergence in both fall and spring as well as for seed bank carryover. ‘Appar’ seeds lack these predictive and carryover mechanisms.

Simulation of Soil Erosion from Winter Runoff in the Palouse Prairie

ABSTRACT A soil erosion simulation study was conducted to help understand the severe soil loss from agricultural lands in the Palouse prairie of the Pacific Northwest. Soil erosion models are seldom written for or used in areas where snowmelt and frozen soils are prominent in aggra-vating erosion by rainfall impact and overland flow. A physically based soil erosion model was developed and coupled with the University of Idaho version of the USDAHL watershed model. The main factors used to calculate rill development and sheet erosion on upland areas as well as channel erosion are precipitation, over-land flow, streamflow, snowmelt, organic materials (crop residues and mulches), soil properties, and soil moisture. The soil loss from each hydrologic zone is cascaded to a lower area and finally to the channel. The erosion model obtains all runoff and watershed definitions from USDAHL and, therefore, follows the same cascading scheme. The use of this cascading system shows the amount and location, in terms of hydrologic zones, where erosion and deposition occur. Channel erosion is negligible compared with upland erosion for the smaller of two test agricultural watersheds. For the larger water-shed, channel erosion is a significant source of soil loss but upland erosion is still dominant. The erosion model cannot be adequately calibrated without acceptable run-off simulation, especially for the overland flow com-ponent. The monthly, yearly, and most daily simulated soil losses were deemed acceptable when compared with the observed values. Some daily simulations did not show good correspondence to observed values. As the simula-tion components of both the runoff and erosion models are better defined, the erosion model can serve to evalu-ate or determine soil erosion problems or to support other erosion related studies.

Winter Food Habits of Short-Eared Owls in the Palouse Prairie

Winter Food Habits of Short-Eared Owls in the Palouse Prairie

A Method of Estimating Carcass Fat and Fat-Free Weights in Migrant Birds from Water Content of Specimens

this seemed to be the northern limit of their range for at least another decade. The eventual expansion that now extends throughout the Palouse Prairie country of northern Idaho and eastern Washington and into the Spokane area, while well known to local ornithologists, has apparently never been thoroughly documented. There is now evidence that a similar invasion has reached the vicinity of Missoula in western Montana. The AOU Check-list (1957), in outlining the range of this species, mentions Montana only as follows: In winter . . . casual north to Alberta (Topaz Lake) and Montana (Santon Lake). Davis, in his checklist of the birds of Montana (Proc. Montan Acad. Sci. 16:5, 1956) mentio s sight records of Hou e Finches in Helena and Bozeman. Additional Montana recor s include the following by Dr. P. L. Wright, Department of Zoology, U iversity of Montana, and myself. Wright's observations were near his home in southeastern Missoula, while mine included both residential and rural areas near the southern outskirts of the city (table 1). From these records there seems to be little doubt that the House Finch is well on the way toward becoming an established resident in this area.

Mule Deer and Elk Food Habits on the National Bison Range

The reduction program of surplus elk and mule deer on the National Bison Range in western Montana in 1951 and 1952 provided an opportunity to determine the relative food habits of these two game species (Cervus canadensis and Odocoileus hemionus) on a range that is predominantly grassland. The Pauline pasture was selected as a source of animals. It is 5,566 acres in size. It contains the principal forage species and plant-cover types of the Bison Range and is accessible throughout the year. Fig. 1 illustrates the extent and distribution of the main cover types. The grassland consists largely of Palouse Prairie vegetation, with bluebunch wheatgrass (Agropyron spicatum) as the principal species. The forested portion of the pasture is predominantly Douglas-fir (Pseudotsuga menziesii [P. taxifolia]) on northern exposures and ponderosa pine (Pinus ponderosa) on the southern exposures. Swales and drainage courses contain snowberry (Symphoricarpos occidentalis) and hawthorn ( Crataegus douglasii). Rocky outcrops and stony areas give rise to scattered stands of chokecherry (Prunus demissa), serviceberry (Amelanchier alnifolia), and mockorange (Philadelphus lewisii). Rocky Mountain maple (Acer glabrum) is commonly found as an understory species in the forest type. Ninebark (Physocarpus malvaceus) is abundant at the margins of the Douglas-fir type. Fig. 2 shows the arrangement of types relative to the topography of the pasture.