Sporobolus Airoides Research Articles

Prescribed fire and exotic plant responses in phreatophytic Sarcobatus vermiculatus rangelands with contrasting degradation

The effects of fire seasonality and prescribed burning on exotic species invasion are poorly understood in black greasewood (Sarcobatus vermiculatus) plant communities of North America. The impacts of reintroducing fire in the fall and spring on community composition and current-year biomass were evaluated at two such sites, one dominated by exotic annual C3 grasses in Miles City, Montana, USA, and one dominated by native perennial C4 grasses in Laramie, Wyoming, USA. Study sites were assessed based on existing Ecological Site Description (ESD) and State-and-Transition Models (STMs) and the Montana site was determined to be more degraded than the Wyoming site. Experimental design was a randomized complete block design with burns conducted in the fall of 2020 and spring of 2021. Exotic species such as Bromus arvensis were reduced by 56% in spring burned plots the following year and by 25% in the fall burned plots over the course of the study in Montana (58.3–43.5%) and Bromus tectorum did not increase in spring or fall burned plots in Wyoming. Accordingly, the proportion of native species in both plant communities remained constant and native perennial C4 grasses such as Sporobolus airoides were resilient to fire. Moreover, burn treatment had no negative effects on plant species richness, evenness, or diversity in either location. Fire treatments had variable effects on current-year biomass with variable influences of drought and season of burn. Prescribed fire, regardless of season, did not exacerbate exotic plant species spread or reduce native species dominance in either location – suggesting that phreatophytic S. vermiculatus rangelands near the eastern terminus of their range are resilient to anthropogenic burning. Future research should investigate the use of prescribed fire with other methods such as revegetation and herbicide application for reducing exotic plant dominance and increasing native plant species.

Forage and vegetal characterization of three native mexican grasses in Tulancingo de Bravo, Hidalgo

Objective: To carry out an agronomical assessment and a quantitative description of the yield components of switchgrass (Panicum virgatum), eastern gamagrass (Tripsacum dactyloides), and alkali sacaton (Sporobolus airoides) under rainfed conditions in Tulancingo, Hidalgo, Mexico.
 Design/Methodology/Approach: A completely randomized block design was used in 31-month-old pastures to determine forage production, morphological composition, seed yield, and weight of 1,000 caryopses. The plants were characterized in 7-month-old pastures, recording (per plant) the number of total and floral stems, as well as the basal twigs in alkali sacaton and switchgrass. Meanwhile, in the case of eastern gamagrass, the dome number and androecium sections were recorded.
 Results: The highest forage dry matter production was observed in switchgrass: 9,322 kg ha-1 (P < 0.05). Eastern gamagrass had a higher leaf ratio (1:3). The highest number of seeds was recorded in alkali sacaton: 211 kg ha-1, with 43% physical purity. After 7 months of sowing, a total of 250, 355, and 280 stems and 193, 150, and 87 floral stems were recorded in switchgrass, alkali sacaton, and eastern gamagrass, respectively.
 Study Limitations/Implications: Eastern gamagrass produces a low number of seeds; therefore, it must be propagated by plant material. In rainfed soils, grasses help to recover pasture areas, since rainfed agriculture poses a risk in many places as a result of poor rainfall distribution or early frosts.
 Findings/Conclusions: The three grasses studied are productive due to the amount of forage accumulated. Alkali sacaton produces more seeds.

TRADITIONAL AND UPDATED EVALUATION OF THE RANGELAND SITE AND CONDITION IN THE SEMIARID SCRUB OF THE HIGH PLATEAU

In Mexico, the concepts of rangeland site and condition are not well known. For this reason, most of the rangelands of private ranches on the high plateau of San Luis Potosí and Zacatecas are undergoing a process of severe generalized deterioration. The purpose of this study was to survey and characterize multi-branched rangeland sites of three beef cattle ranches on the San Luis Potosí-Zacatecas High Plateau, as well as to assess their condition using a quantitative ecological method complemented by updated technological tools. The hypothesis proposed was that the site and condition of rangeland evaluated with the quantitative ecological method (used for grasslands and soil), complemented by updated technology, are also identifiable in multi-branched rangelands of this type of production units on the San Luis Potosí-Zacatecas High Plateau. Based on a Landsat satellite image, an unsupervised classification process was performed for the three ranches, which was then confirmed by field observations. A total of 11 sites were surveyed, three on each ranch (microphyll desert scrub, predominantly Bouteloua gracilis; microphyll desert scrub, with predominance of Sporobolus airoides; and an ecotone between microphyll desert scrub and rosetophile desert scrub) and two exclusive locations (crassicaule scrub and rosetophile desert scrub with predominance of Muhlenbergia villiflora). Rangeland condition was evaluated by measuring density and volume (volumetric biomass) of the main plant species, categorized by forage value, and the actual state of the soil surface was assessed in terms of bare soil and vegetation, litter, feces and rock cover. The data were ordered and classified with the DECORANA and TWINSPAN modules from the PC-ORD program. Site and condition evaluation under this approach was satisfactory for surveying the state of the rangelands of the three private cattle ranches studied on the San Luis Potosí-Zacatecas High Plateau.

Versatile Native Grasses and a Turf-Alternative Groundcover for the Arid Southwest United States

Abstract Water use limitations offers new opportunities for utilization of low-input native grasses and groundcovers for the landscapes of southwest USA. Two field studies were conducted with eleven plant species for two years in Scottsdale and Sun City West, AZ to evaluate rate of emergence, ground surface coverage, plant height, and overall plant quality. In the laboratory, Eragrostis tef at 86% and Eragrostis intermedia at 85% were showing higher percentage of germination compared to other species. Within eight weeks, ten species exhibited an average of 81% emergence at Scottsdale while nine species showed only 58% emergence at Sun City West. Sporobolus cryptandrus grew to greater than 76 cm (30 in) in height while kurapia (Lippia nodiflora) grew to about 5 cm (2 in). The performances of the groundcover kurapia and the native grasses tested demonstrated excellent potential in the low desert southwest U.S., with low rates of water use, applying fertilizer only at planting, and less frequent mowing requirements. Lippia nodiflora, Sporobolus airoides, Bouteloua gracilis, Eragrostis intermedia, and Muhlenbergia asperifolia remained green throughout the year when mowed twice a year. Lippia nodiflora, Hilaria rigida, and Bouteloua gracilis exhibited the highest ground surface coverage and uniformity in growth. Index words: groundcover, landscape, low input, native grasses, plant species. Species used in this study: Blue grama, Bouteloua gracilis (Kunth) Lag. ex Griffiths; bufflograss, Buchloe dactyloides (Nutt.) Engelm.; plains lovegrass, Eragrostis intermedia A.S. Hitchc.; teff, Eragrostis tef (Zucc) Trotter; big galleta, Hilaria rigida (Thurb); Kurapia, Lippia nodiflora (L.) Greene; alkali muhly, Muhlenbergia asperifolia (Nees & Meyen ex Trin.) Parodi; alkali sacaton, Sporobolus airoides (Torr.) Torr.; spike dropseed, Sporobolus contractus A.S. Hitchc.; sand dropseed, Sporobolus cryptandrus (Torr.) A. Gray; and desert zinnia, Zinnia acerosa (DC.) A. Gray.

Variations in Groundwater Level and Microtopography Influence Desert Plant Communities in Shallow Aquifer Areas

An improved understanding of the relationships among vegetation, groundwater level, and microtopography is crucial for making well-informed management decisions in areas with shallow groundwater resources. We measured plant species abundance/composition and richness in relation to depth to groundwater (DTW) and microtopography in Owens Valley, California, particularly in areas where DTW ranged from 0 to 4 m. Sampling occurred along 67 vegetation transects across three community types. Relationships between DTW and community composition were evaluated using non-metric multidimensional scaling (NMS), while non-parametric multiplicative regression was used to relate DTW and microtopography to species abundance. The dominant gradient in species composition (NMS Axis 1) explained ~51% of variation in our distance matrix and was most strongly associated (r = 0.55) with DTW. The graminoids Juncus arcticus, Leymus triticoides, and Distichlis spicata had strong affinities toward areas with the shallowest DTW (<1.5 m). One salt-adapted species Sporobolus airoides and one shrub Ericameria nauseosa dominated areas with intermediate DTW (1.5-2.0 m), whereas the shrubs Atriplex torreyi, Sarcobatus vermiculatus, and Artemisia tridentata were dominant in areas with deeper DTW (>2.0 m). Variation in microtopography affected species abundance and increased species richness for vegetation communities at either extreme of the water table gradient, shallow, and deep DTW but not the intermediate DTW. Findings indicate that desert plant communities from shallow aquifers have adapted to different DTW and microtopography conditions and that considering those adaptations may be important to manage groundwater and vegetation resources in these areas.

Germination and early establishment of dryland grasses and shrubs on intact and wind-eroded soils under greenhouse conditions

AimsGrassland-to-shrubland transition is a common form of land degradation in drylands worldwide. It is often attributed to changes in disturbance regimes, particularly overgrazing. A myriad of direct and indirect effects (e.g., accelerated soil erosion) of grazing may favor shrubs over grasses, but their relative importance is unclear. We tested the hypothesis that topsoil “winnowing” by wind erosion would differentially affect grass and shrub seedling establishment to promote shrub recruitment over that of grass.MethodsWe monitored germination and seedling growth of contrasting perennial grass (Bouteloua eriopoda, Sporobolus airoides, and Aristida purpurea) and shrub (Prosopis glandulosa, Atriplex canescens, and Larrea tridentata) functional groups on field-collected non-winnowed and winnowed soils under well-watered greenhouse conditions.ResultsNon-winnowed soils were finer-textured and had higher nutrient contents than winnowed soils, but based on desorption curves, winnowed soils had more plant-available moisture. Contrary to expectations, seed germination and seedling growth on winnowed and non-winnowed soils were comparable within a given species. The N2-fixing deciduous shrub P. glandulosa was first to emerge and complete germination, and had the greatest biomass accumulation of all species.ConclusionsGermination and early seedling growth of grasses and shrubs on winnowed soils were not adversely nor differentially affected comparing with that observed on non-winnowed soils under well-watered greenhouse conditions. Early germination and rapid growth may give P. glandulosa a competitive advantage over grasses and other shrub species at the establishment stage in grazed grasslands. Field establishment experiments are needed to confirm our findings in these controlled environment trials.

Nutrient uptake and gas exchange of Great Basin plants provide insight into drought adaptations and coexistence

Abstract Aims Although increases in precipitation variability in arid ecosystems are projected due to climate change, the response of desert shrub communities to precipitation change has not been fully elucidated. Such knowledge is important since drought-adapted plants exhibit varied mechanisms of survival that may contribute to species coexistence. Methods We tested the responses of eight drought-adapted plants, a mix of graminoids, shrubs and forbs to three summer precipitation scenarios (1.3, 2.6 and 3.9 cm per month) in a common garden experiment in the Great Basin (Owens Valley, California). Changes in mineral nutrient uptake (carbon, nitrogen, phosphorus, potassium, calcium, magnesium, manganese, copper, boron, zinc, iron and sodium) and gas exchange parameters (photosynthetic rate and stomatal conductance) were investigated in the studied species. Important Findings Two graminoids (Sporobolus airoides and Leymus triticoides) and one salt tolerant shrub species (Atriplex confertifolia) responded to increased water availability with increases in photosynthetic rate and/or stomatal conductance. There was a significant correlation between water availability and uptake of nutrients for five out of eight species. Artemisia tridentata, with higher rates of photosynthesis, contained greater amounts of potassium, copper and boron, while Juncus arcticus, with higher rates of photosynthesis, contained greater amounts of magnesium and iron, and less sodium. Juncus arcticus and three salt-adapted species (A. confertifolia, Distichlis spicata and S. airoides) exhibited correlations with stomatal conductance and concentrations of nutrients. Results indicate that differential physiological response mechanisms to increased moisture and associated nutrient uptake strategies in drought-adapted species may mediate coexistence under increased summer precipitation.

Cooperation between Sporobolus airoides and associated arbuscular mycorrhizal fungi for phosphorus acquisition under drought conditions in an oligotrophic desert ecosystem

Plants from phosphorus (P) limited environments have developed various strategies for acquiring P from the soil, and for maintaining P homeostasis within the plant. We analyzed the mechanisms of phosphorus acquisition used by the grass Sporobolus airoides-rhizosphere microbiota during two years with contrasting annual rainfall in an extreme P-oligotrophic ecosystem. We determined arbuscular mycorrhizal fungi (AMF) root and soil colonization, and the activity of three P-related eco-enzymes over two consecutive years. We also determined C, N, and P concentrations and ratios in plant biomass, microbial biomass and soil for assessing nutrient homeostasis of soil microbial community and plants. S. airoides invested more carbon in the AMF symbiosis in the drought year in the site more limited by P (Pozas Azules site). Additionally, the specific activity of phosphomonoesterases was higher in this site, suggesting that the microbial community invests more energy to produce this enzyme to release P from organic molecules. In conclusion, our results show evidence of the importance of AMF symbiosis for S. airoides to cope with P and water limitations in a highly oligotrophic ecosystem.

Apparent Seed Digestibility and Germination of Seeds After Passage Through the Digestive System of Northern Bobwhite (Colinus virginianus)

Limited information is available regarding the digestibility or germination of seeds after passage through the digestive system of northern bobwhites (Colinus virginianus), especially of plants associated with the sand sagebrush (Artemisia filifolia)–mixed prairie community. Thus, our objectives were to determine the apparent digestibility of seeds of 45 plant species associated with the sand sagebrush–mixed prairie community and the germination of seeds before and after passage through the digestion system of bobwhites. Seeds of 12 of 45 species fed to bobwhites were found to pass through the digestive system intact. The apparent seed digestion pattern of the 12 plant species with incomplete digestion of seeds was legumes > forbs > grasses > shrubs. At the end of a 7-d germination period, the digestion of seeds by bobwhites reduced seed germination of alkali sacaton (Sporobolus airoides), black-eyed Susan (Rudbeckia hirta), and western yarrow (Achillea millefolium var. occidentalis) but increased the germination of white prairie clover (Dalea candida) seeds (P ≤ 0.05). However, the germination percentage of predigestion seeds of white prairie clover exceeded that of postdigestion seeds (P < 0.05) by the end of a 21-d germination period. Averaged across species, the 21-d seed germination of postdigestion seeds was lower than predigestion seeds (P < 0.05). Viable seeds found in feces are disseminated by quail onto the landscape. Plant species that have been lost from overgrazing or the application of herbicides might be reintroduced onto landscapes through dissemination by bobwhites via food plots, feeding stations, or both if the seeds are deposited onto a suitable germination substrate with suitable seed germination conditions.

Potential Consequences of Repeated Severe Drought for Shortgrass Steppe Species

Future climate projections indicate temperatures in the shortgrass steppe region are likely to increase up to 3°C by midcentury, with a corresponding reduction in soil moisture even without precipitation deficit. Although periodic drought is a natural disturbance in shortgrass rangeland, negative effects on characteristic shortgrass species are possible as the frequency and severity of drought events increase in comparison with recent historic norms. As part of a study intended to detect vegetation changes at a shortgrass steppe site on Colorado’s eastern plains, frequency and canopy cover percentage were measured in 37 permanently marked plots over a period of 17 yr. The study period included the two lowest total annual precipitation yr (2002 and 2012) in the period of record for regional weather stations, exceeding even the driest years of the extended 1930s drought. Growing season mean temperatures during those drought years were 1°C and 1.6°C above the 1971−2000 average, respectively. Three of the six perennial grass species monitored showed a decline over the period of the study. Blue grama (Bouteloua gracilis), a dominant and important forage species in the shortgrass steppe, declined in both cover and frequency, while alkali sacaton (Sporobolus airoides), not an important forage species, slightly increased. In addition to changes in graminoid dominance, we observed an increase in cholla (Cylindropuntia imbricata) and a decrease in sandsage (Artemisia filifolia) densities between 1999 and 2015. Even if total productivity of the shortgrass steppe is maintained under warming and drying conditions, changes in species composition have implications for rangeland quality with regard to its use for livestock grazing and use by wildlife such as small mammals and songbirds.

Candidate halophytic grasses for addressing land degradation: Shoot responses of Sporobolus airoides and Paspalum vaginatum to weekly increasing NaCl concentration

ABSTRACTIn many arid and semiarid regions worldwide, high levels of soil salinity is a key driver of land degradation, as well as a key impediment to re-establishing plant cover. Combating land degradation and erosion associated with soil salinity requires experimental determination of plant species that can grow in soils with high levels of salinity and can be used to re-establish plant cover. Herein, we evaluated the responses of untested candidate cultivars of two halophytic grass species to high soil salinity: alkali sacaton (Sporobolus airoides Torr.) and seashore paspalum (Paspalum vaginatum Swartz). We evaluated the growth responses of both species in a greenhouse under control (no-salt) and various levels of NaCl salinity (EC 8, 16, 24, 32, 40, and 48 dSm−1) using Hoagland solution in a hydroponics system in a randomized complete block design trial. At all salinity levels, sacaton grass had a greater shoot height, shorter root length, lower shoot fresh and dry weights, and poorer color and general quality compared to seashore paspalum. The shoot fresh and dry weights of both grasses were greatest at the low to medium levels of salinity, with the greatest response observed at EC 16 dSm−1. At the highest level, salinity significantly reduced shoot fresh and dry weights of both grasses. Because growth of both halophytic species exhibited high tolerance to salinity stress and were stimulated under low to medium levels of salinity, both species could be considered suitable candidates for re-establishing plant cover in drylands to combat desertification and land degradation associated with high levels of soil salinity.

Relative habitat- and browse-use of native desert mule deer and exotic oryx in the greater San Andres Mountains, New Mexico

Introduced oryx (Oryx gazella gazella) have expanded into the San Andres Mountains of south-central New Mexico, but little is known of concurrent habitat used by oryx and desert mule deer (Odocoileus hemionus crooki); the latter in New Mexico is a species of special concern that has declined signifi cantly since the introduction of oryx. We used fecal-pellet and browse surveys in combination with presence modeling to identify differences in relative use of habitat types, distribution, and browsing of highly palatable, highly preferred (hereafter, key) plant species during 2004 to 2006 to assess the potential for direct competition in use of resources in the San Andres Mountains. Numbers of pellet groups per transect (hereafter referred to as relative use) of oryx was greatest in sandsage (Artemisia fi lifolia) shrublands and alkali sacaton (Sporobolus airoides) grasslands, whereas mule deer-use was greatest in oak- (Quercus spp.) mountain mahogany (Cercocarpus montanus) shrublands, and pinyon- (Pinus edulis) juniper (Juniperus spp.) woodlands. Use of key mule deer browse species was low (<4.0% of current annual growth browsed) in all habitat types. Relative use of oryx accounted for 42% of the variation in browse percentages in pinyon-juniper woodlands and 58% of the variation in mesquite (Prosopis glandulosa) shrublands, whereas mule deer-use accounted for 79% of the variation in oak-mountain mahogany shrublands and 27% in pinyon-juniper woodlands. Presence models similarly indicated that deer distribution was most positively associated with oak-mountain mahogany shrublands and pinyon-juniper woodlands, while oryx distribution was most positively associated with alkali sacaton grasslands, mixed lowland scrub, and sandsage shrublands. Presence models also indicated that areas closer to roads were positively associated with presence of mule deer and oryx, as were southern aspects for oryx and higher elevations for mule deer. Relationships with roads were likely driven by other attributes (e.g., water sources, arroyos, and canyons) associated with these areas in the San Andres Mountains. Current management strategies aimed at limiting oryx numbers in woodland and shrubland habitat types located in mountainous areas of the San Andres Mountains that show highest use by mule deer should continue to aide in recovery of mule deer populations.

Impacts of Imazapyr and Triclopyr Soil Residues on the Growth of Several Restoration Species

Herbicides are frequently used in natural systems to control invasive plants, but nontarget impacts from persistent soil residues can result in unintended ecosystem effects. Imazapyr and triclopyr are herbicides that are widely used in noncrop areas such as rangelands to manage perennial weeds, especially woody species such as tamarisk (saltcedar). Due to widespread environmental and anthropogenic changes in the American southwest, tamarisk, which is commonly thought to co-occur only with riparian plants, is increasingly being found in communities of upland rangeland species. Using an in vitro study combined with high-performance liquid chromatography (HPLC) analyses, imazapyr and triclopyr degradation rates were determined in six Colorado soils. In addition, the relative sensitivity of desirable species to the two herbicides was determined in a field dose response study. Exponential decay models estimated that triclopyr degradation (half-lives of 5−16 days) was 20 times more rapid than imazapyr degradation (half-lives of 82−268 days). All species tested were sensitive to imazapyr residues, but the degree of sensitivity was strongly dependent on soil properties. Sensitive species (alkali sacaton and western wheatgrass) were tolerant of imazapyr residues in some soils 20−23 months after applications. Relatively insensitive species (slender wheatgrass) were tolerant of imazapyr residues in the same soils 10 months after applications. American licorice was sensitive to triclopyr residues up to 89 days after applications, and several grasses (including sideoats grama) showed minor sensitivity. Our study indicates that there is an interaction between the spatial variability in herbicide degradation driven by edaphic properties and the sensitivity of plants to a herbicide, which could be exploited by management practitioners to aid in site rehabilitation. Specifically, managers could stagger planting of species temporally on the basis of their sensitivity to herbicide residues or could target areas of treated sites for planting that are known to have soil types facilitating relatively rapid herbicide degradation.

New experimental hosts of Barley yellow dwarf virus among wild grasses, with implications for grassland habitats

Barley yellow dwarf virus (BYDV), an economically important virus, infects small grain cereal crops and over 150 other Poaceae species. BYDV infection plays an important role in competition among grasses in non‐managed systems, but many grasses remain unexamined as potential BYDV hosts. This study examined grass species that have not been reported as BYDV hosts but are commonly encountered in non‐managed grasslands throughout the United States and Canada. Laboratory inoculations with BYDV‐PAV using the aphid vector Rhopalosiphum padi were performed to examine the ability of 13 grass species and barley to be infected with the virus; eight of the grass species were not documented previously as virus hosts. Serological and molecular assays were used to confirm BYDV‐PAV infection. Plant height, number of leaves, number of tillers and weight were recorded to evaluate susceptibility or sensitivity to BYDV. Infection with BYDV was experimentally achieved for the first time on Achnatherum lettermanii, Achnatherum occidentale, Achnatherum thurberianum, Danthonia intermedia, Poa fendleriana, Sporobolus airoides and Sporobolus cryptandrus, but not on Alopecurus pratensis and Elymus wawawaiensis. Infection was confirmed in Bromus inermis, Elymus elymoides, Poa bulbosa, Poa secunda and Hordeum vulgare, which served as controls. BYDV infection caused reductions in plant height on P. bulbosa and P. fendleriana. BYDV‐infected P. secunda had more leaves per plant compared to healthy plants of the same species. BYDV‐infected A. lettermanii exhibited reduced dry weight in both below‐ground and above‐ground tissue. These findings have implications for the management and conservation of grassland habitats.

Patterns of Water Use by Great Basin Plant Species Under Summer Watering

We analyzed temporal and spatial patterns of water use by a functionally-diverse group of Great Basin plant species and determined their water use rates at the whole-plant and individual-leaf scales under variable summer watering. Species studied were the desert grasses Distichlis spicata and Sporobolus airoides, the desert shrubs Artemisia tridentata, Ericameria nauseosa, and Atriplex confertifolia; the wetland/riparian plants Juncus arcticus, Leymus triticoides, and Salix exigua; and the annual exotic Salsola tragus. Plant species were individually grown in 5.8 m2 plots in a common garden in eastern California. Three irrigation treatments in the form of monthly pulses were applied during the summer: low (1.3 cm), medium (2.6 cm), and high (3.9 cm), in addition to a nonirrigated control. Whole-plant water uptake characteristics were determined by soil water depletion at different soil depths, while leaf transpiration was determined by gas exchange. Whole-plant water extraction and leaf transpiration varied similarly among species. Desert shrubs had low water extraction (35 to 395 g m−2 day−1) and were not affected by irrigation. The desert grasses and riparian/wetland species had higher water extraction, increasing with irrigation levels. L. triticoides and J. arcticus had the highest water extraction overall (>2,000 g m−2 day−1). Desert shrubs relied 10 times more on deeper water sources than herbaceous species. The average T/ET was 31%, but varied by species. Summer available water in environments such as the Great Basin favors desert grasses and riparian/wetland species, but not desert shrubs. The observed species differences provide alternatives for water and vegetation management.

Vegetation Response in a Colorado Grassland-shrub Community to Extreme Drought: 1999–2010

We examined vegetation changes in a mixed grassland-shrub community in eastern Colorado between 1999–2010, a period that encompassed both extreme drought and moisture recovery, as well as slightly higher than long term average temperatures. Shrub cover significantly increased while grass cover significantly decreased following the drought years of 2002–2003. Grass cover had still not fully recovered 7 y after the drought, primarily due to the slow recovery of blue grama (Bouteloua gracilis). Blue grama was no longer dominant in this community, becoming secondary in importance to alkali sacaton (Sporobolus airoides). Increase in shrub cover and density were especially notable in rabbitbrush (Ericameria nauseosa) and tree cholla (Cylindropuntia imbricata). Although rabbitbrush density declined in the drought, overall cover of remaining individuals increased, even during the drought. Cholla density increased by nearly 200 plants/ha from 543 plants/ha to 726 plants/ha, all post drought.

Fate and movement of selenium from drainage sediments disposed onto soil with and without vegetation

Disposal options for salty and selenium-laden agricultural drainage sediments are needed to protect the agricultural ecosystem in Central California. Thus, a 7-year pilot-scale field study evaluated the effects of disposing Se-laden drainage sediment onto soil that was planted with either salado grass (Sporobolus airoides ‘salado’) or cordgrass (Spartina patens ‘Flageo’), or on soil left bare with and without irrigation. Significant decreases in salinity and water-extractable and total soil Se concentrations were observed in all treatments to a depth 30 cm, while water extractable Se and salinity increased most significantly between 30 and 60 cm. Total yields increased over time for both species, while plant Se concentrations were ≈10 and 12 mg kg−1 DM for salado and cordgrass, respectively. The results show that Se and soluble salts disposed of as Se-laden drainage sediment onto light textured soils will significantly migrate to lower depths with or without vegetation.

Factors Influencing Foraging Habitats of Mule Deer (Odocoileus hemionus) in the San Andres Mountains, New Mexico

Abstract We documented characteristics of habitats and related these to foraging needs of mule deer (Odocoileus hemionus) in the San Andres Mountains, Dona Ana, Sierra, and Socorro counties, New Mexico. Cover by forbs was related positively to rainfall during the primary growing season in mixed-lowland scrub, sand sagebrush (Artemisia filifolia), alkali sacaton (Sporobolus airoides), and creosotebush (Larrea tridentata) habitats. Cover by palatable and preferred forages was low (≤8.6%) in 2004, 2005, and 2007, years of average rainfall, and increased slightly in 2006 (≤9.3%) during above-average rainfall. During years of average rainfall, cover by forbs was related negatively to percentage cover by shrubs, to density of honey mesquite (Prosopis glandulosa), sand sagebrush, and grama grass (Bouteloua), and to canopy and density of trees in pinyon–juniper (Pinus–Juniperus) woodlands. Important species of browse were in all habitats, but only grama grass (n = 9), pinyon–juniper (n = 12), and oak–mountain mah...

Native Grasses Collected from Invasions Demonstrate Invasion Resistance

Native grasses can persist in areas dominated by invasive species, yet resistance to invasion by the selected remaining natives is largely unknown. We examine native grass lineages differing in history of survival within invasions, when transplanted into association with 2 invasive perennials. Invaded plants were collected from Russian knapweed ( Rhaponticum repens ) invasions, and non-invaded plants were collected outside invasions. We assess growth and reproduction of alkali sacaton ( Sporobolus airoides ) in the presence of Russian knapweed (the original invader) and Canada thistle ( Cirsium arvense ), an invasive species to which the grasses lacked exposure. On 2 field sites (Crowheart, WY and Cheyenne, WY) and in an environmentally controlled lab at the University of Wyoming, we monitored plant growth (longest leaf, basal circumference, and tiller production) of grass lineages from the 2 histories with and without the presence of the invaders. We monitored invasive species recruitment, grass seedling germination, and grass seedling establishment to determine grass fecundity and resistance to invasive encroachment. At Crowheart, when competing with Russian knapweed, invaded plants were larger than non-invaded plants, irrespective of sampling date. At Cheyenne, invaded plants competing with Canada thistle grew larger than non-invaded grasses irrespective of sampling date. In the controlled growth chamber, growth of the 2 histories differed on few dates, yet non-invaded lineages had greater leaf growth, and seedling germination was greater for invaded grasses. Lines of native grasses collected from within historic invasions display competitive growth traits in field transplants that may be useful for reclamation.

Growth, water productivity, and biomass allocation of Great Basin plants as affected by summer watering

ABSTRACTThis study measured water‐use efficiency of wildland vegetation at the whole‐plant level during two contrasting years to better understand ecosystem responses to precipitation fluctuations in the Great Basin, USA. Biome‐representative species included grasses (Distichlis spicata, Leymus triticoides, and Sporobolus airoides), desert shrubs (Artemisia tridentata, Atriplex confertifolia, and Ericameria nauseosa), wetland/riparian plants (Glycyrrhiza lepidota, Juncus arcticus, and Salix exigua), and an exotic annual (Salsola tragus). Plants were grown in 5·8 m2 plots in a common garden in eastern California. Four watering treatments were applied monthly during two summers: control (no water other than natural precipitation), low (1·3 cm), medium (2·6 cm), and high (3·9 cm). Water‐use efficiency, here termed water to production (WTPa), was the ratio of water transpired to aboveground biomass produced. Biomass production was 50% lower and WTPa was five times higher during 2009 than 2010. WTPa decreased with watering during 2009 but increased with watering during 2010. Year differences determined vegetation productivity and response to summer watering and were related to the lower winter/spring precipitation during 2009 than 2010. Desert shrubs were more drought tolerant than grasses and wetland plants. Yet, an increase in summer precipitation would primarily benefit herbaceous species and not desert shrubs. Desert shrubs achieved greater standing crop but lower root‐to‐shoot ratio (RSR) than herbaceous species. Nonetheless, the grass S. airoides had the greatest standing crop overall, mainly because of its greater root production (RSR 5·5). Species differences in growth, WTPa, and biomass allocation should be considered in land management and conservation practices. Copyright © 2012 John Wiley &amp; Sons, Ltd.