Festuca Octoflora Research Articles

Biocrusts do not differentially influence emergence and early establishment of native and non‐native grasses

AbstractBiological soil crusts (biocrusts) cover the soil surface of global drylands and interact with vascular plants. Biocrusts may influence the availability and nature of safe sites for plant recruitment and the susceptibility of an area to invasion by non‐native species. Therefore, to investigate the potential role of biocrusts in invasive species management, we sought to determine whether native and non‐native grass recruitments in two North American deserts were differentially affected by biocrusts. We conducted a series of coordinated experiments in field, semi‐controlled, and controlled environment settings in the Colorado Plateau and Sonoran Desert using contrasting biocrust and grass functional types. Experiments in field environments focused on early establishment of grass seedlings whereas controlled environment experiments focused on seedling emergence. Within each experiment, we compared responses (frequency, magnitude, and timing of emergence/establishment) both across species (biocrust types pooled) and across species and levels of biocrust development. Native grasses varied by experiment and included Aristida purpurea, A. purpurea var. longiseta, Bouteloua gracilis, and Vulpia octoflora. Emergence of non‐native Bromus tectorum was similar to that of native grasses on the Colorado Plateau. Differences in emergence of native vs. non‐native grasses in the Sonoran Desert were species‐ and response‐specific. Emergence of the non‐native Bromus rubens was comparable to that of native grasses whereas emergence frequency and magnitude of the non‐native Pennisetum ciliare was lower compared with two of four native species. Within a grass species, emergence was higher and faster on bare soil compared with biocrusts in the Sonoran Desert semi‐controlled and greenhouse environment experiments. However, the pattern was not consistent across other experiments. When comparing across Colorado Plateau and Sonoran Desert biocrusts in greenhouse experiments, we found that emergence of native grasses was higher on Colorado Plateau biocrusts. Based on the lack of consistent results across our experiments, grass recruitment on biocrusts appears to be driven more by species‐specific traits than species provenance. Our greenhouse experiments suggest that biocrust topographic relief is an important safe site trait influencing plant recruitment.

Seasonal Timing of Fire Alters Biomass and Species Composition of Northern Mixed Prairie

Fire plays a central role in influencing ecosystem patterns and processes. However, documentation of fire seasonality and plant community response is limited in semiarid grasslands. We evaluated aboveground biomass, cover, and frequency response to summer, fall, and spring fires and no fire on silty and clayey sites in semiarid, C3-dominated grassland. The magnitude of change in biomass between years was greater than any differences among fire treatments. Still, differences existed among seasons of fire. Summer fire reduced non-native annual forb frequency (3% vs. 10% ± 2%) and Hesperostipa comata, reduced native annual forbs the first year, increased Poa secunda and bare ground, and increased Vulpia octoflora the second year. Fall fire increased grass biomass (1224 vs. 1058 ± 56 kg∙ha−1), but fall fire effects were generally similar to those of summer fire. Spring fire effects tended to be intermediate between no fire and summer and fall fire with the exception that spring fire was most detrimental to H. comata the first growing season and did not increase bare ground. All seasons of fire reduced litter, forb biomass, and frequency of Bromus japonicus and Artemisia spp., and they reduced H. comata, V. octoflora, and native annual forbs the first year, but increased basal cover of C3 perennial grasses (2.2% vs. 0.6% ± 0.4%). Fire during any season increased dominance of native species compared with no fire (6.6% vs. 2.0% ± 1.0% basal cover) and maintained productivity. Seasonal timing of fire manipulated species composition, but increased C3 perennial grass cover and native species dominance with fire during any season indicated that using fire was more important than the season in which it occurred. In addition, fire effects on the vegetation components tended to be counter to previously observed effects of grazing, suggesting fire and grazing may be complementary.

Dormant-Season Fire Inhibits Sixweeks Fescue and Enhances Forage Production in Shortgrass Steppe

Semiarid rangelands experience substantial interannual variability in precipitation, which can determine the relative abundance of species in any given year and influence the way that fire affects plant community composition and productivity. Long-term studies are needed to examine potential interactions between fluctuating community composition and the role of fire in these ecosystems. Here, we report on an 11-year (2006 to 2016) study of annual and triennial dormant-season prescribed fires in the semiarid shortgrass steppe of Colorado, USA. Productivity of the dominant C4 shortgrasses was not reduced by dormant-season burns in any year. The C3 annual grass, six-weeks fescue (Vulpia octoflora [Walter] Rydb.) was rare during the first 7 years (2006 to 2012) but, following drought in 2012, increased dramatically in unburned plots (2013 to 2016). Both spring and autumn annual burns reduced fescue biomass during 2014 to 2016 by an average of 87%. Autumn triennial burns prior to the 2013 and 2016 growing seasons similarly reduced fescue (86%), while spring triennial burns implemented prior to the 2012 and 2015 growing seasons did not. Results indicate that burning during fescue establishment can prevent proliferation, but burning two years later when fescue had reached peak abundance was ineffective. All three burn treatments that suppressed fescue subsequently enhanced C4 grass production. We suggest that rangeland managers be aware of the potential for sixweeks fescue germination and establishment during warm, wet winters that follow drought years, and consider the use of dormant-season prescribed fire to adaptively reduce negative impacts on forage production.

Negative impacts of invasive plants on conservation of sensitive desert wildlife

AbstractHabitat disturbance from development, resource extraction, off‐road vehicle use, and energy development ranks highly among threats to desert systems worldwide. In the Mojave Desert, United States, these disturbances have promoted the establishment of nonnative plants, so that native grasses and forbs are now intermixed with, or have been replaced by invasive, nonnative Mediterranean grasses. This shift in plant composition has altered food availability for Mojave Desert tortoises (Gopherus agassizii), a federally listed species. We hypothesized that this change in forage would negatively influence the physiological ecology, immune competence, and health of neonatal and yearling tortoises. To test this, we monitored the effects of diet on growth, body condition, immunological responses (measured by gene transcription), and survival for 100 captive Mojave tortoises. Tortoises were assigned to one of five diets: native forbs, native grass, invasive grass, and native forbs combined with either the native or invasive grass. Tortoises eating native forbs had better body condition and immune functions, grew more, and had higher survival rates (>95%) than tortoises consuming any other diet. At the end of the experiment, 32% of individuals fed only native grass and 37% fed only invasive grass were found dead or removed from the experiment due to poor body conditions. In contrast, all tortoises fed either the native forb or combined native forb and native grass diets survived and were in good condition. Health and body condition quickly declined for tortoises fed only the native grass (Festuca octoflora) or invasive grass (Bromus rubens) with notable loss of fat and muscle mass and increased muscular atrophy. Bromus rubens seeds were found embedded in the oral mucosa and tongue in most individuals eating that diet, which led to mucosal inflammation. Genes indicative of physiological, immune, and metabolic functions were transcribed at lower levels for individuals fed B. rubens, indicating potential greater susceptibility to disease or other health‐related problems. This study highlights the negative indirect effects of invasive grasses, such as red brome, in desert ecosystems, and provides definitive evidence of a larger negative consequence to health, survival, and ultimately population recruitment for Mojave Desert tortoises than previously understood.

CO2ENRICHMENT REDUCES THE ENERGETIC COST OF BIOMASS CONSTRUCTION IN AN INVASIVE DESERT GRASS

To examine how global change could influence species invasions, we compared the responses of energetic processes and growth of invasive and native grass species to atmospheric CO2 enrichment in an intact Mojave Desert ecosystem. Combined with its modest influence on photosynthetic activity, elevated atmospheric CO2 was associated with a significant reduction in the energetic cost of aboveground biomass construction in invasive Bromus madritensis spp. rubens (red brome) without a concurrent cost reduction in native Vulpia octoflora (six-weeks fescue). Consequently, the invasive grass species grew faster, grew bigger, and produced more seeds with atmospheric CO2 enrichment than the native grass species. As a physiological mechanism of invasive species success driven by CO2 enrichment, such alterations in biomass construction costs combined with increased photosynthetic activity could trigger a shift in the species composition of this ecosystem, and potentially that of other invaded ecosystems, toward increa...

Are Mojave Desert annual species equal? Resource acquisition and allocation for the invasive grass Bromus madritensis subsp. rubens (Poaceae) and two native species

Abundance of invasive plants is often attributed to their ability ot outcompete native species. We compared resource acquisition and allocation of the invasive annual grass Bromus madritensis subsp. rubens with that of two native Mojave Desert annuals, Vulpia octoflora and Descurainia pinnata, in a glasshouse experiment. Each species was grown in monoculture at two densities and two levels of N availability to compare how these annuals capture resources and to understand their relative sensitivities to environmental change. During >4 mo of growth, Bromus used water more rapidly and had greater biomass and N content than the natives, partly because of its greater root-surface area and its exploitation of deep soils. Bromus also had greater N uptake, net assimilation and transpiration rates, and canopy area than Vulpia. Resource use by Bromus was less sensitive to changes in N availability or density than were the natives. The two native species in this study produced numerous small seeds that tended to remain dormant, thus ensuring escape of offspring from unfavorable germination conditions; Bromus produced fewer but larger seeds that readily germinated. Collectively, these traits give Bromus the potential to rapidly establish in diverse habitats of the Mojave Desert, thereby gaining an advantage over coexisting native species.

The Regeneration Potential of a Threatened Southern Illinois Shale Barren

MCCALL, R. K. AND D. J. GIBSON. The regeneration potential of a threatened southern Illinois shale barren. J. Torrey Bot. Soc. 126:226-233. 1999.-The soil seedbank of a threatened shale barren community was monitored for one year to determine the regeneration potential of the site following restoration efforts by the Illinois Department of Natural Resources. Sixty-four soil samples were collected from sixteen 50 m2 circular plots distributed equally between restored and unrestored sections of the barren. Data were analyzed using a MannWhitney test and detrended correspondence analysis (DCA). A total of 50 taxa were identified from the seedbank. All but four species were native to southern Illinois and fourteen differed significantly between restored and unrestored portions of the barren. The distribution of plots along the first two axes of two detrended correspondence analyses, based upon the seedbank or aboveground vegetation, showed a clear separation of restored and unrestored plots. Soil moisture and overstory canopy coverage appeared to be the two main variables influencing species' distribution along these axes. Comparison of the seedbank with previous site inventories indicated a shift in species composition in the restored portion of the shale barren since restoration began. It is anticipated that, as restoration efforts continue, the site will shift from a mesic to a xeric association of vegetation, such as Schizachyrium scoparium and Vulpia octoflora, representative of barrens communities.

Vegetation Biomass Dynamics and Patterns of Sexual Reproduction in a Northern Mixed-Grass Prairie

The sustainability of natural grasslands is in large part dependent upon the successful ingress and propagation of alien plant species. We attempted to characterize the propagation potential of the dominant plant species of a southeastern Montana mixed-grass prairie community including two introduced grasses, Bromus japonicus and B. tectorum. Aboveground standing crops and densities of seeds were estimated on 10 dates between September 1991 and August 1993 and seedling densities were estimated on 21 dates between September 1991 and July 1993. Total aboveground standing crop ranged from about 110 to 340 g m−2 and was dominated by three grasses: Bouteloua gracilis, a warm-season, perennial; Pascopyrum smithii, a cool-season, perennial; and B. japonicus, a cool-season, annual grass. Seed production was dominated by B. japonicus (∼10,400 seeds m−2). Bouteloua gracilis and P. smithii seed production was negligible with maximum densities of about 120 and 25 seeds m−2, respectively. Density of seedlings was greatest for B. japonicus (∼2100 seedlings m−2), Festuca octoflora (∼1100 seedlings m−2), and Plantago patagonica (∼350 seedlings m−2). Maximum number of B. gracilis seedlings was 25 m−2. No P. smithii seedlings were observed during the study. Temporal differences in seedling densities were closely tied to late summer-early fall precipitation patterns. Although community-level seed production and seedling establishment processes were dominated by B. japonicus, the overwhelming presence of herbage produced by the two vegetative propagating species, B. gracilis and P. smithii, casts doubt on a trend in ecological succession toward an annual grass-dominated community.

Influence of cryptobiotic soil crusts on elemental content of tissue of two desert seed plants

Soil surface growths dominated by cyanobacteria and the lichen Collema in southeastern Utah are shown to be associated with greater tissue content of several bio‐essential elements in two co‐occurring seed plants (Festuca octoflora, Poaceae, and Mentzelia multiflora, Loasaceae). The elements N, P, K, Ca, Mg, and Fe were present in significantly greater concentrations in Festuca growing on soils heavily encrusted with cyanobacteria and cyanolichens than in plants on the same soil where foot traffic had destroyed the cryptobiotic crusts. With Mentzelia, N, Mg, and Fe were present in significantly greater concentrations in plants from sites with encrusted soil surfaces than on blow‐sand sites. The cryptobiota appeared to compete vigorously with Mentzelia for available P: Mentzelia plants from crusted sites contained significantly smaller concentrations of P than plants grown on soils where wind action precluded development of surface crusts. These cryptobiotic crusts fix considerable amounts of N, which apparently becomes available to associated seed plants via decomposition and cellular secretion processes. Other macronutrients are apparently accumulated in forms available to seed plants as the crusts develop in interspaces between higher plants. The trace element Fe appears to be rendered more available to higher plants by the cryptobiotic growth. That effect may be related to chelating compounds known to be present in the mucilaginous sheaths of cyanobacteria. Other possible reasons are discussed for the enhanced nutrient uptake of seed plants growing in cryptobiotic crusts.

Tracked Vehicle Impacts on Vegetation at the Pinon Canyon Maneuver Site, Colorado

AbstractThe effects of military tracked vehicle maneuvers on the vegetation of the Pinon Canyon Maneuver Site (PCMS), southeastern Colorado, were assessed from 1985 to 1987. Tracking decreased plant basal and litter cover and increased bare ground. The immediate effect of tracking was to reduce perennial warm‐season grasses [primarily blue grama, Bouteloua gracilis (H.B.K.) Lag. ex. Griffith] followed by the invasion of annual cool‐season grasses [sixweeks grass, Vulpia octoflora (Walt.) Rybd., and little barley, Hordeum pusillum Nutt.] and annual warm‐season forbs [sunflower, Helianthus annuus L., russian thistle, Salsola iberica Sennen & Pau, and kochia, Kochia scoparia (L.) Schrab.]. In untracked areas, herbaceous plant composition did not change; however, litter increased and bare ground and basal cover decreased. Changes in cover in untracked areas was attributed to above average precipitation and the cessation of domestic livestock grazing. Overall (tracked plus untracked areas), total cover increased on PCMS, but the proportion of annual cover also increased. Woody plant density decreased an average of 9% from 1985 to 1987. Long‐term management of the soil and vegetative resources of PCMS are discussed.

Effects of Short-Duration Grazing on Winter Annuals in the Texas Rolling Plains

A study was conducted in the Texas Rolling Plains to test the hypotheses that short-duration grazing increases plant density and diversity in grasslands. Densities of 9 species of winter annual forbs and 2 species of annual grass were compared in short-duration grazed and ungrazed areas for 2 years. Livestock grazing in spring and early summer affected density of 8 winter annuals the following winter. Densities of 2 grasses [little barley (Hordeum pusillum Nutt.) and six-weeks fescue (Vulpia octoflora [Walt.] Rydb.)] and 3 forbs [common broomweed (Xanthocephalum dracunculoides [DC.]), Gordon's bladderpod (Lesquerella Gordonii [Gray] Wats.), and Texas filaree (Erodium texanum Gray.)] were higher in grazed areas; 3 forbs [bitterweed (Hymenoxys odorata DC.), spurge (Euphorbia sp.), and woolly plaintain (Plantago patagonica Jacq.) were more abundant in exclosures. Richness and diversity of winter annuals generally were not affected by grazing. Increased precipitation during germination and establishment greatly increased the density of winter annuals.

Responses of Desert Annual Plants to Ozone and Water Stress in anin situExperiment

Desert winter annual plants: Camissonia claviformis, C. hirtella, Caulanthus cooperi, Chaneactis carphoclinia, C. stevioides, Cryptantha angustifolia, C. pterocarya, Erodium cicutarium, Festuca octoflora, Lupinus concinnus, Oenothera californica, Plantago insularis, Platystemon californica, Salvia columbariae, Thelypodium lasiophyllum, and Thysanocarpus curvipes growing on irrigated and non-irrigated plots were exposed in situ to elevated levels of ozone dispensed from an open air exposure system. Plants were exposed intermittently to a gradient of ozone of concentrations ranging between 44 and 133 ppb (nL L−1) for 35 h over a total of 216 h. Only three species were injured by ozone at the highest ozone concentrations. Leaf injury to C. claviformis—2 percent total foliar injury (TFI), C. hirtella—1 percent TFI, and Erodium cicutarium—2 percent TFI, developed at the highest ozone concentrations. Leaf injury to these species was similar on the irrigated and nonirrigated plots. Leaf water potential and stoma...

L-tryptophan transaminase of a bacterium isolated from the rhizosphere of Festuca octoflora (graminae)

Cell-free extracts of a rhizobacterial isolate from Festuca octoflora Walt. contained a soluble α-ketoglutarate-dependent L-tryptophan (L-TRP) transaminase which catalyzes the conversion of L-TRP to indole-3-pyruvic acid (IPyA). The enzyme was purified 35-fold with protamine sulfate and ammonium sulfate (45–65%) precipitation. The IPyA released in the reaction mixture was trapped and partially stabilized as an enol-borate-arsenate complex and measured spectrophotometrically. IPyA production was directly proportional with time (up to 120min) and protein concentration in the ranges employed. The optimum pH and temperature for the catalytic conversion was pH 8.0 and 40°C, respectively. Using L-TRP as the substrate in the presence of α-ketoglutarate (as an amino-group acceptor) and pyridoxal phosphate (as a coenzyme), the average K m was 1.22 mM and the activation energy 21.0 kJ mol −1. The role of this enzyme in the microbial synthesis of auxins and its possible influence on plant growth and development are discussed.

Effects of Ozone or Sulfur Dioxide on Annual Plants of the Mojave Desert

Forty-seven species of annual plants from the Mojave Desert were grown in pots and exposed in open-top field chambers located at Riverside, California to test their relative sensitivity to SO2 and 0 3 . Exposures were 8 h/day for four or five days at 0,0.05, 0.1, 0.2, 0.3 and 0.4 ppm O3 or 0, 0.2, 0.5, 0.6, 0.8, 1.0 and 1.5 ppm SO2. Species differed widely in their response to the pollutants. Three species, Camissonia claviformis, Camissonia hirtella and Cryptantha nevadensis, were quite sensitive to both pollutants, exhibiting leaf injury when exposed to 0.1 ppm O3 or 0.2 ppm SO2. Two species: Festuca octoflora and Lepidium lasiocarpum were tolerant to both pollutants, exhibiting no leaf injury with concentrations of 0.3 ppm O3 or 1.5 ppm SO2. The other species were intermediate in sensitivity, with O3 sensitivity not always corresponding to SO2 sensitivity. Total sulfur concentration analysis indicated that for 8 of 11 species tested, plants exposed to 0.2 ppm SO2 had a higher sulfur concentration than nonexposed plants. Baileya pleniradiataand Perityle emoryi had the greatest increases in sulfur concentration for exposed versus control plants. To test for effects of the environmental and exposure system on plant sensitivity, 29 of the species exposed in the open-top chambers were grown in the ground and exposed with a modified chamberless zonal air pollution (ZAP) system to SO2 in the Mojave Desert area near Daggett, California. Exposures were for a total of 37 h over six days to 0, 0.4, 0.8 and 1.0 ppm SO2 with exposures only during periods with due west winds. Most of the species were not injured with any of the S02 exposure concentrations used with the ZAP system; only Camissonia claviformis showed injury at 0.8 ppm SO2 and Oenothera californica exhibited injury at 1.0 ppm SO2.

Effect of Range Condition on the Diet and Performance of Steers Grazing Native Sandhills Range in Nebraska

Effect of Range Condition on the Diet and Performance of Steers Grazing Native Sandhills Range in Nebraska

Response of Western North Dakota Mixed Prairie to Intensive Clipping and Five Stages of Development

Response of Western North Dakota Mixed Prairie to Intensive Clipping and Five Stages of Development

Factors Affecting Seed Reserves in the Soil of a Mojave Desert Ecosystem, Rock Valley, Nye County, Nevada

During 1972, a 2nd year of low herb production, there was a significant variation of seed reserves in the upper 2 cm of soil, with a doubling from February to June and a density-independent halving by October. In October 1972 there were 8 X 106 seeds/ha (5.3 kg/ha). After very high herb production in the spring, seed densities in October 1973 were 10-16 times greater under shrubs and 23-27 times greater in exposed areas (max 187.5 X 106 seeds/ha, 84.3 kg/ha). The increase was principally by the winter annual grass, Festuca octoflora. In 1972, when there was a small difference in rodent density between two plots (0.8:1.0), there was no effect of rodents on seed density. In 1973, when there was a 1:17.8 ratio of rodent densities, there was a significant effect on seeds under shrubs. Then from October 1973 to October 1974, seed reserves in exposed areas between shrubs decreased by 20% in the plot with few rodents, and by 40% in the plot with many rodents. Eating of seeds by rodents accounted for 30 to 80% of the seed reserve decreases observed. Germination losses were no more than 25%. There is slight evidence that pocket mice selectively decrease abundance of the heavier species of seeds. Seed density was at least five times greater under shrubs than in exposed areas ; density was significantly correlated with the size of shrub canopy. There was also a significant effect of the species of shrub on the density of seeds. During years of low production, under-shrub areas are a refuge for herb seed production, and in such years shrub seeds form a larger portion of the seed crop and new reserves. The difference in response of shrubs and herbs to weather increases the stability of seed reserves. In May 1973 the number of herbs per 100 seeds in the previous October was 16.8 under shrubs and 43.6 in exposed areas; this implies a minimum germination of 24% of seeds over the whole habitat. It takes an exceptional coincidence of events, even in deserts, to cause a severe depletion of seed reserves.

Controlling Sixweeks Fescue on Shortgrass Range

Controlling Sixweeks Fescue on Shortgrass Range

The prehistoric and historic role of the cool-season grasses in the southwest

The Navajo Indian, always an astute observer of the natural world, called Festuca octoflora "the grass that feared the summer." We recognize this species and others as cool-season grasses, or ones that utilize winter and spring moisture to promote their growth. In the grasslands and the pinyon-juniper woodlands of the Southwest many people accept the sparsity of cool-season grasses as a condition of long standing. The present obscurity of the cool-season grasses belies a time when deer, antelope, and buffalo grazed on the more abundant blades, and people depended on the grain for sustenance. The cool-season grasses mature in early summer, a critical time of year for the hunter-gatherer and the agriculturalist. For each, stored food supplies descend to their lowest annual level. New crops are immature. The cool-season grass grain provides a ready source of abundant calories that can be immediately consumed and also stored. Harvested grain bridges the growing season until the first of the wild fruits mature in the summer. Both cliff shelters and caves in the Southwest preserve evidence of prehistoric utilization of cool-season grasses. The dry interior of Tularosa cave in westcentral New Mexico saved mutton grass (Poa fendleriana) from decay. Large amounts of chaff, piles of panicles with grains missing, and knotted bundles of

Aerial Photography and Statistical Analysis for Studying Behaviour Patterns of Grazing Animals

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