Grass Establishment Research Articles

겉뿌림을 위한 오차드그라스와 톨페스큐 종자의 코팅 및 펠렛팅 기술 비교

초지조성과 개량에서 겉뿌림은 중요한 방법 중의 하나이다. 오늘날 겉뿌림 초지조성에서 종자피복기술은 관심이 높아지고 있다. 따라서 본 시험은 산지초지에서 겉뿌림조성시 목초의 출현율과 정착율을 높이기 위해 화본과목초종자의 피복기술을 개발하기 위하여 실시하였다. 종자 펠렛팅은 피복시간을 단축하고 단위시간당 피복량을 증가시킴으로서 종자피복의 새로운 기술로 평가되었다. 펠렛종자의 건조시간을 단축하고 건조온도를 낮춤으로서 화본과 목초종자의 발아세와 발아율이 증가하였다. 임간초지에서 펠렛종자는 종자의 출현, 정착 및 초기생육을 향상시켰다. 이상의 시험결과를 볼 때 임간초지에서 종자 펠렛팅 기술은 화본과목초의 정착과 초기생육 향상을 위한 새로운 기술로 평가되었다. Surface sowing method is one of the important methods to establish seeds in mountainous area. Seed-coating technique in the surface sowing method is increasing interest in the world today. An experiment was conducted to develope a technique for pelleting seeds of grass in woodland. Results showed that the seed pelleting was a useful technique than coating seeds because the pelleting reduced coating time and increased amounts of coated seeds per hour. As lowering temperature and reducing time for drying, germinating energy and germination rate of pelleted seeds were improved. And emergence, establishment and early growth of pelleted were also improved in pasture under woodland. Based on this study, we could conclude that the seed pelleting is a useful technique for the establishment and early growth of grass under woodland.

Field-Scale Assessment of Uncertainties in Drip Irrigation Lateral Parameters

Grass establishment on railway embankment steep slopes for erosion control in Central Queensland, Australia, is aided by drip lateral irrigation systems. The effective field values of the lateral parameters may be different from the manufacturer supplied ones due to manufacturing variations of the emitters, environmental factors, and water quality. This paper has provided a methodology for estimating drip lateral effective parameter values under field conditions. The hydraulic model takes into account the velocity head change and a proper selection of the friction coefficient formula based on the Reynolds number. Fittings and emitter insertion head losses were incorporated into the hydraulic model. Pressure measurements at some locations within the irrigation system, and the inlet discharges, were used to calibrate the lateral parameters in a statistical framework that allows estimation of parameter uncertainties using the Metropolis algorithm. It is observed that the manufacturer’s supplied parameters were significantly different from the calibrated ones, underestimating pressures within the irrigation system for a given inlet discharge, stressing the need for field testing. The parameter posterior distributions were found to be unimodal and nearly normally distributed. The emitter head loss coefficient distribution being very significant suggests the need to incorporate it into the hydraulic modeling. Although the example given in this paper relates to steep slopes, the methodologies are general and can be applied to any use of drip laterals.

On soil moisture–vegetation feedbacks and their possible effects on the dynamics of dryland ecosystems

Soil moisture is the environmental variable synthesizing the effect of climate, soil, and vegetation on the dynamics of water‐limited ecosystems. Unlike abiotic factors (e.g., soil texture and rainfall regime), the control exerted by vegetation composition and structure on soil moisture variability remains poorly understood. A number of field studies in dryland landscapes have found higher soil water contents in vegetated soil patches than in adjacent bare soil, providing a convincing explanation for the observed preferential establishment of grasses and seedlings beneath tree canopies. Thus, because water is the limiting factor for vegetation in arid and semiarid ecosystems, a positive feedback could exist between soil moisture and woody vegetation dynamics. It is still unclear how the strength of such a feedback would change under different long‐term rainfall regimes. To this end, we report some field observations from savanna ecosystems located along the south‐north rainfall gradient in the Kalahari, where the presence of relatively uniform sandy soils limits the effects of covarying factors. The data available from our field study suggest that the contrast between the soil moisture in the canopy and intercanopy space increases (with wetter soils under the canopy) with increasing levels of aridity. We hypothesize that this contrast may lead to a positive feedback and explore the implications of such a feedback in a minimalistic model. We found that when the feedback is relatively strong, the system may exhibit two stable states corresponding to conditions with and without tree canopy cover. In this case, even small changes in environmental variables may lead to rapid and largely irreversible shifts to a state with no tree canopy cover. Our data suggest that the tendency of the system to exhibit two (alternative) stable states becomes stronger in the more arid regions. Thus, at the desert margins, vegetation is more likely to be prone to discontinuous and abrupt state changes.

Evaluation of Herbicides for Restoring Native Grasses in Buffelgrass‐Dominated Grasslands

Abstract Buffelgrass (Pennisetum ciliare) is an exotic grass that threatens arid and semiarid ecosystems. The objective of this study was to determine effectiveness of several herbicides at reducing competition from buffelgrass to enhance establishment of planted native grasses. In Duval County, Texas, plots were delineated in two experiments in a buffelgrass‐dominated pasture and mowed on 2 September 2002. On 18 September 2002 and 7 October 2002, a 41% glyphosate (N‐(phosphonomethyl) glycine) herbicide was applied to all plots. A mixture of three native grasses—green sprangletop (Leptochloa dubia), plains bristlegrass (Setaria leucopila), and four‐flower trichloris (Chloris pluriflora)—was planted on 8 October 2002. On 9 October 2002, 1.12 and 2.24 kg/ha of a 80% tebuthiuron (N‐[5‐(1,1‐dimethyethyl)‐1,3,4‐thiadiazol‐2‐yl]‐N,N’‐dimethylurea) herbicide was applied preemergence to the first experiment, and all other herbicides were applied postemergence on 27 July 2003 to the second experiment. Percent canopy cover of vegetation was estimated with a 20 × 50–cm sampling frame during April, June, and October 2003 and August 2004. Postemergent herbicides had no significant effect on canopy cover of buffelgrass or planted species (p≥ 0.05). Canopy cover of native grasses did not exceed 8% on any treatment or sampling date, and buffelgrass cover returned to pre‐treatment conditions in less than 1 year; however, the 2.24 kg/ha rate of tebuthiuron suppressed (p < 0.05) canopy cover of buffelgrass compared with controls and increased (p < 0.05) native grasses almost 2 years past application. Tebuthiuron may have potential value in reducing buffelgrass canopy cover and increasing cover of native grasses, particularly Chloris spp.

Yard Waste Compost as a Stormwater Protection Treatment for Construction Sites

Runoff water quality improvement from three yard waste compost erosion control treatments were compared with two conventional treatments and an untreated control on plots of 3:1 slope during two growing seasons, using natural events and simulated rainfall. Runoff volume, suspended solids, nutrients, biomass, turf shear strength, and turfgrass color scale were monitored. The most effective compost treatment, a 5-cm thick blown compost blanket, produced 12.7 times less runoff and 9.8 times less sediment load than a straw mat and silt fence treatment. The compost treatments generated eight times more biomass than the straw mat treatments. Root development was significantly better on the compost treatments based on turf shear strength measurements. Tilled-in compost was not as effective as a compost blanket at reducing sediment loss, particularly before the establishment of grass on the plot. The cost of compost treatments was similar to that of straw mat with silt fence treatments.

RESTORING NATIVE GRASSES AS VEGETATIVE BUFFERS IN A COASTAL CALIFORNIA AGRICULTURAL LANDSCAPE

ABSTRACT We investigated changes in vegetation composition of different grass buffer strips in a fragmented coastal agricultural landscape to evaluate the potential for native grass restoration of sites that receive agricultural runoff. Vegetative buffers bordering Elkhorn Slough, draining into Monterey Bay, California, were either seeded with a non-native annual grass (Hordeum vulgare) or with a mix of native perennial grasses (Bromus carinatus, Deschampsia cespitosa, Nassella pulchra), and above-ground biomass and cover of vegetation were measured over a 4-yr period. Based on preliminary results, we initiated a second, smaller-scale experiment to test establishment of native perennial grasses (Bromus carinatus, Elymus glaucus, Hordeum brachyantherum) at different seeding densities with combinations of non-native annual grasses (H. vulgare or Lolium multiflorum and Vulpia myuros) to optimize erosion control. In the first experiment, plots seeded with non-native annual grasses had greater biomass than nat...

Using long time series of Landsat data to monitor fire events and post-fire dynamics and identify driving factors. A case study in the Ayora region (eastern Spain)

The Ayora region, situated about 60 km southwest of the city of Valencia/Spain, was chosen to demonstrate pathways of characterizing fire events and post-fire succession in Mediterranean ecosystems using multi-temporal satellite imagery. A corresponding time series of 6 Landsat MSS, 13 Landsat-5 TM and 1 Landsat-7 ETM + images, covering the period 1975—2000, was processed to account for geometric and radiometric distortions as well as sensor calibration. Spectral Mixture Analysis was applied to derive estimates of photosynthetic active green vegetation cover as a primary indicator. A combination of pixel-based linear trend analysis and diachronic thresholding was employed to procure a fire perimeter data base and characterize post-fire dynamics based on a temporally stratified trend analysis. The results were integrated with auxiliary information to evaluate driving factors and further interpreted in relation to field-based information on plant communities and post-fire succession patterns. Reflecting typical recovery phases with an initial establishment of grasses and herbaceous species, followed by a gradual development of a shrub layer and the subsequent colonization of tree individuals, temporal trajectories could be described by exponential functions and were related to plot-based botanical information.

Non-Composted Municipal Solid Waste Processing Byproduct Effect on Soil Reclamation

ABSTRACT A new garbage processing technology has been developed that sterilizes and separates inorganic and organic components of municipal solid waste. The non-composted byproduct of this process, Fluff®, has the potential to be utilized as a soil amendment to improve soil conditions in highly degraded soils. A study was initiated to evaluate Fluff as a soil amendment for establishing native grasses on disturbed US Army training lands. The Fluff was incorporated into a sandy loam soil at Fort Benning Military Reservation, GA on two sites: a moderately degraded and a highly degraded soil. The Fluff was incorporated at rates of 0, 18, 36, 72, and 143 Mg ha− 1 to assess the effects on soil properties for two growing seasons. The addition of Fluff improved available plant nutrients and soil pH levels at both sites. Also, Fluff reduced the level of soil bulk density and increased soil concentration of carbon (C) and nitrogen (N). Because no adverse environmental effects were detected and Fluff improved soil physical and nutrient conditions as well as improving perennial grass establishment with increasing application rates, land application of Fluff to degraded US Army training grounds could be considered a viable and beneficial alternative to current waste management practices.

Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland‐shrubland ecotones

AbstractQuestion: Does shrub invasion at ecotones indirectly limit grass establishment by increasing mammalian seedling herbivory?Location: Chihuahuan Desert, New Mexico, USA.Methods: We tested the hypothesis that herbivore‐related mortality of seedlings of the dominant perennial grass Bouteloua eriopoda would be highest in shrub‐dominated portions of grassland‐shrubland ecotones. We tested the hypothesis in two Chihuahuan Desert sites featuring similar shrub encroachment patterns but different shrub species, grass cover, and different abundances of small mammals. Within each site we transplanted B. eriopoda seedlings to grass‐dominated, middle, and shrub‐dominated positions of replicate ecotones during the time of year (mid‐summer) when they would naturally appear and monitored seedling fates. We estimated population size/activity of putative small mammal herbivores.Results: Seedlings were killed by mammals in greater numbers in shrubland than in grassland or middle ecotone positions at the site with large herbivore numbers. At the site with low herbivore numbers, most seedlings were killed in middle ecotone positions. The abundance patterns of herbivores did not parallel patterns of seedling herbivory across the ecotones or between sites.Conclusions: Seedling herbivory is an important process and is related to vegetation composition, but the mechanisms underlying the relationship are not clear. We speculate that variation in small mammal foraging behavior may contribute to seedling herbivory patterns. Restoration strategies in the Chihuahuan Desert need to account for the abundance and/or behavior of native herbivores.

Effects of Frequent Mowing on Survival and Persistence of Forbs Seeded into a Species‐Poor Grassland

Abstract Many early attempts at tallgrass prairie reconstruction failed to achieve the high species diversity of remnant prairies, and instead consist primarily of C4 grasses. We hypothesized that frequent mowing of established prairie grasses could create sufficient gaps in the aboveground and belowground environment to allow for the establishment of native forbs from seed. We studied forb seedling establishment in a 25‐year‐old prairie planting in northern Iowa that was dominated by native warm‐season grasses. In winter 1999, 23 species of native forbs were broadcast into the recently burned sod at a rate of 350 viable seeds/m2. Treatment plots were mowed weekly for either one or two growing seasons, and control plots were unmowed. Mowed plots had greater light availability than controls, especially when warm‐season grasses began to flower. Overwinter seedling mortality was 3% in mowed treatments compared to 29% in the controls. Forbs in mowed plots had significantly greater root and shoot mass than those in control plots in the first and second growing seasons but were not significantly more abundant. By the fourth growing season, however, forbs were twice as abundant in the mowed treatments. No lasting negative impacts of frequent mowing on the grass population were observed. Mowing a second year influenced species composition but did not change total seedling establishment. Experimental evidence is consistent with the idea that mowing reduced competition for light from large established grasses, allowing forb seedlings the opportunity to reach sufficient size to establish, survive, and flower in the second and subsequent years.

Plant functional group responses to fire frequency and tree canopy cover gradients in oak savannas and woodlands

Questions: How do fire frequency, tree canopy cover, and their interactions influence cover of grasses, forbs and understorey woody plants in oak savannas and woodlands? Location: Minnesota, USA. Methods: We measured plant functional group cover and tree canopy cover on permanent plots within a long-term prescribed fire frequency experiment and used hierarchical linear modeling to assess plant functional group responses to fire frequency and tree canopy cover. Results: Understorey woody plant cover was highest in unburned woodlands and was negatively correlated with fire frequency. C4-grass cover was positively correlated with fire frequency and negatively correlated with tree canopy cover. C3-grass cover was highest at 40% tree canopy cover on unburned sites and at 60% tree canopy cover on frequently burned sites. Total forb cover was maximized at fire frequencies of 4–7 fires per decade, but was not significantly influenced by tree canopy cover. Cover of N-fixing forbs was highest in shaded areas, particularly on frequently burned sites, while combined cover of all other forbs was negatively correlated with tree canopy cover. Conclusions: The relative influences of fire frequency and tree canopy cover on understorey plant functional group cover vary among plant functional groups, but both play a significant role in structuring savanna and woodland understorey vegetation. When restoring degraded savannas, direct manipulation of overstorey tree canopy cover should be considered to rapidly reduce shading from fire-resistant overstorey trees. Prescribed fires can then be used to suppress understorey woody plants and promote establishment of light-demanding grasses and forbs.

Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland-shrubland ecotones

Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland-shrubland ecotones

Predicting Need for Phosphorus Fertilizer by Soil Testing During Seeding of Cool Season Grasses

Recent changes in soil testing methodology, the important role of P fertilization in early establishment and soil coverage, and new restrictions on P applications to turf suggest a need for soil test calibration research on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb), and perennial ryegrass (Lolium perenne L.). Greenhouse and field studies were conducted for 42 days to examine the relationship between soil test P levels and P needs for rapid grass establishment using 23 NJ soils with a Mehlich-3 extractable P ranging from 6 to 1238 mg·kg–1. Soil tests (Mehlich-1, Mehlich-3, and Bray-1) for extractable P were performed by inductively coupled plasma–atomic emission spectroscopy (ICP). Mehlich-3 extractable P and Al were measured to evaluate the ratio of P to Al as a predictor of need for P fertilizer. Kentucky bluegrass establishment was more sensitive to low soil P availability than tall fescue or perennial ryegrass. Soil test extractants Mehlich-1, Bray-1, or Mehlich-3 were each effective predictors of need for P fertilization. The ratio of P to Al (Mehlich-3 P/Al %) was a better predictor of tall fescue and perennial ryegrass establishment response to P fertilization than soil test P alone. The Mehlich-1, Bray-1, and Mehlich-3 soil test P critical levels for clipping yield response were in the range of 170 to 280 mg·kg–1, depending on the soil test extractant, for tall fescue and perennial ryegrass. The Mehlich-3 P/Al (%) critical level was 42% for tall fescue and 33% for perennial ryegrass. Soil test critical levels, based on estimates from clipping yield data, could not be determined for Kentucky bluegrass using the soils in this study. Soil testing for P has the potential to aid in protection of water quality by helping to identify sites where P fertilization can accelerate grass establishment and thereby prevent soil erosion, and by identifying sites that do not need P fertilization, thereby preventing further P enrichment of soil and runoff. Because different grass species have varying critical P levels for establishment, both soil test P and the species should be incorporated into the decision-making process regarding P fertilization.

Variation in the establishment of a non-native annual grass influences competitive interactions with Mojave Desert perennials

Competition between native and non- native species can change the composition and structure of plant communities, but in deserts, the highly variable timing of resource availability also influences non-native plant establishment, thus modulating their impacts on native species. In a field experiment, we varied densities of the non- native annual grass Bromus madritensis ssp. rubens around individuals of three native Mojave Desert perennials—Larrea tridentata, Achnathe- rum hymenoides, and Pleuraphis rigida—in either winter or spring. For comparison, additional plots were prepared for the same perennial species and seasons, but with a mixture of native annual species as neighbors. Growth of perennials declined when Bromus was established in winter because Bromus stands had 2-3 months of growth and high water use before perennial growth began. However, water potentials for the peren- nials were not significantly reduced, suggesting that direct competition for water may not be the major mechanism driving reduced perennial growth. The impact of Bromus on Larrea was lower than for the two perennial grasses, likely because Larrea maintains low growth rates throughout the year, even after Bromus has completed its life cycle. This result contrasts with the perennial grasses, whose phenology com- pletely overlaps with (Achnatherum) or closely follows (Pleuraphis) that of Bromus. In compari- son, Bromus plants established in spring were smaller than those established in winter and thus did not effectively reduce growth of the perenni- als. Growth of perennials with mixed annuals as neighbors also did not differ from those with Bromus neighbors of equivalent biomass, but stands of these native annuals did not achieve the high biomass of Bromus stands that were neces- sary to reduce perennial growth. Seed dormancy and narrow requirements for seedling survivor- ship of native annuals produce densities and biomass lower than those achieved by Bromus; thus, impacts of native Mojave Desert annuals on perennials are expected to be lower than those of Bromus.

Soil Erosion Thresholds and Alternative States in Northeastern Patagonian Rangelands

In semiarid rangelands, continuous grazing may decrease vegetation cover, accelerating soil erosion and eventually causing a transition to an alternative, degraded state. State-and-transition models invoke process-based explanations of alternative states, but there are few examples that use empirical data on key factors and processes. We used rainfall simulation to determine 1) the relationships between soil surface characteristics and interrill erosion in 3 spatially related plant communities: stable grass with scattered shrubs (GS), degraded grass with scattered shrubs (DGS), and degraded shrub steppes (DSS), and 2) the site conservation threshold (SCT) of this rangeland. We also analyzed the effect of past erosion on soil and vegetation characteristics. In the GS, sediment production and sediment concentration were significantly lower (p < 0.05) than in the DGS and the DSS. The main soil protection factors in the GS and in the DGS were perennial grass and litter cover, while in the DSS, gravel cover became the main soil protection factor. The SCT, the point at which the rate of soil erosion increases markedly, corresponded to a plant-and-litter cover close to 90% and occurred within the DGS. Although this plant community may reverse back to the conserved GS, long-term accelerated erosion may result in enough soil loss to trigger irreversible changes and prompt the transition to the DSS. The threshold underlying this transition would be reached when the A horizon is severely reduced by erosion. Under these conditions, the soil hydrological properties are affected irreversibly, preventing perennial grass establishment. While the GS represents a resource conserving plant community, desirable for both forage production and soil protection, the DSS represents a dysfunctional state with a minimum forage value. The DGS represents an unstable and transitional community that, without management intervention to halt soil erosion, will likely change into the DSS. En los pastizales naturales semiáridos, el pastoreo continuo puede disminuir significativamente la cobertura de la vegetación, acelerar la erosión del suelo y eventualmente causar una transición hacia estados alternativos degradados. Los modelos de estados y transiciones generalmente explican estados alternativos en función de distintos procesos, sin embargo hay pocos ejemplos que usen datos empíricos. Nosotros empleamos lluvia simulada a los fines de determinar 1) las relaciones entre las características superficiales del suelo y la vegetación y la erosión laminar en 3 comunidades vegetales espacialmente relacionadas: una estepa herbácea con arbustos (EH), una estepa herbácea degradada con arbustos (EHD), y una estepa arbustiva degradada (EAD), y 2) el umbral de conservación del sitio (UCS) en éste pastizal. También analizamos el efecto de la erosión histórica sobre las características superficiales del suelo y la vegetación. En la EH la producción y la concentración de sedimentos fueron significativamente más bajos (p < 0.05) que en la EHD y la EAD. Los principales factores de protección del suelo en la EH y la EHD, fueron los pastos perennes y el mantillo, mientras que en la EAD, la cobertura de gravas fue el principal factor de protección del suelo. El UCS, definido como el punto donde la tasa de erosión de suelo aumenta notablemente, se correspondió con una cobertura de pastos perennes y mantillo cercana al 90% y ocurrió dentro de la EHD. Si bien ésta comunidad puede revertir hacia la EH, la erosión acelerada mantenida durante largo tiempo puede producir una pérdida de suelo tan importante como para provocar cambios irreversibles e iniciar la transición hacia la EAD. El umbral subyacente a la transición se alcanzaría cuando, como consecuencia de la pérdida de suelo, el horizonte A es severamente reducido. Bajo estas condiciones, las propiedades hidrológicas del suelo son afectadas irreversiblemente, limitando el establecimiento de pastos perennes. Mientras que la EH tiene una alta capacidad para conservar los recursos del suelo, representa la comunidad vegetal deseable tanto para la producción de forraje como para la protección del suelo, la EAD representa una comunidad con baja capacidad para conservar los recursos del suelo y bajo valor forrajero. La EHD es una comunidad inestable y transicional que, sin un plan de manejo tendiente a detener la erosión acelerada del suelo, cambiará irreversiblemente a una estepa arbustiva degradada.

The tolerance of newly emerged broadleaved tree seedlings to the herbicides clopyralid, cycloxydim and metazachlor

Summary In direct-seeded woodlands and nursery seed-beds, weeds can rapidly invade newly sown areas, leading to death or suppression of tree seedlings. Hand weeding is usually expensive, and the safe use of broad-spectrum contact herbicides is seldom possible. Hence in the work reported here, the tolerance of young tree seedlings to the potentially more selective, post-emergence herbicides clopyralid, cycloxydim and metazachlor, was tested. Seedlings of Fraxinus excelsior L. (ash) with two to four expanded true leaves (2 – 4 ETL), Fagus sylvatica L. (beech) (2 – 4 ETL), Acer pseudoplatanus L. (sycamore) (4 – 6 ETL), Prunus avium L. (cherry) (6 – 8 ETL) and Quercus robur L. (oak) (6 – 8 ETL) appeared to tolerate applications of cycloxydim at a rate of 0.45 kg a.i. ha − 1 . Applications of 0.2 kg a.i. ha − 1 clopyralid or 1.25 kg a.i. ha − 1 metazachlor also appeared to be generally tolerated, but did cause some suppression of annual growth increment in Q. robur , P. avium , F. sylvatica and A. pseudoplatanus , particularly where repeat applications were made to the earliest growth stages. Seedling survival was unaffected by any herbicide treatment. Mixtures of all three herbicides were no more damaging than the same herbicides applied separately. Therefore, depending on tree species and growth stage, it appears that clopyralid could potentially be safely used to control a range of herbaceous weed species, metazachlor a variety of seedling or germinating weeds and cycloxydim a range of established grass weed species, in direct sown woodlands or nursery seed-beds, although further research is advisable to confi rm crop safety.

POTENTIAL FOR SUCCESSIONAL THEORY TO GUIDE RESTORATION OF INVASIVE-PLANT-DOMINATED RANGELAND

Ecologists are searching for models, frameworks, and principles that provide a bridge between theory and the practice of restoration. Successional management has been proposed as a useful model for managing and restoring invasive-plant-dominated rangeland because it provides a framework in which ecological processes can be manipulated by managers to achieve a desired plant community. Successional management identifies three general causes of succession (site availability (disturbance), species availability (colonization), and species performance) and suggests that managers address the ecological process influencing each general cause in a coordinated fashion to direct plant community dynamics. We tested successional management using various techniques to restore invasive-weed-dominated rangeland. Our hypothesis was that successively modifying the factors influencing the causes of succession in an integrated fashion would favor the establishment and abundance of native grasses over singularly applied treatments. Thus, we anticipated that the majority of responses to multiple treatments would be explained by higher order interactions, especially in the final year of the study (2004). To test this hypothesis, we used a model system within a Festuca campestris/Pseudoroegneria spicata habitat among pothole wetlands dominated by Centaurea maculosa and Potentilla recta, two invasive species. We used three herbicide treatments (none, 2,4-D, and picloram) to influence species performance; two seeding methods (imprinting, i.e., creating a small depression and broadcasting, and no-till drilling) to influence disturbance; three seeding rates (977, 1322, and 1557 seeds/m 2 ) to influence colonization; and two cover crop treatments (with and without Triticum aestivum) to influence soil N and favor native grasses. Treatments were factorially arranged and replicated four times in a randomized complete block design in 2001 and sampled in 2002 and 2004. As predicted, plant response to treatments was dominated by two- and three-way interactions in 2004. The highest seeding rate (colonization) combined with no-till drilling (disturbance) produced the highest native grass density in 2002. These effects persisted into 2004 for P. spicata, but not for F. campestris or F. idahoensis. Combining picloram with no-till drill seeding also produced a high density of P. spicata. Drill seeding at 977 seeds/m 2 favored F. idahoensis density, while no-till drilling at 1322 seeds/m 2 favored its biomass in 2004. F. idahoensis established well after drill seeding with a cover crop and applying 2,4-D. Herbicides reduced native forb density and/or biomass, with early season forbs being more sensitive to picloram and summer forbs being more sensitive to 2,4-D. Herbicides increased exotic grasses' density and biomass but had no effect on native grasses. In most cases, integrating treatments that addressed multiple causes of succession favored a desired plant community. Thus, we accomplished our goal of using successional management to direct plant communities toward native desired species, but the treatments used did not improve species richness. Since naturally occurring native forbs did not respond favorably to any treatment combination, ecological restoration using successional management may best be thought of as an iterative procedure where various components and processes of the system are methodically repaired or replaced over time.

Effects of an Uncomposted Municipal Waste Processing By‐Product on Prairie Grass Establishment

A garbage processing technology has been developed that sterilizes and separates inorganic and organic components of municipal solid waste. A study was initiated to evaluate the uncomposted organic by‐product of this process as a soil amendment for establishing native prairie grasses on disturbed Army training lands. The waste was incorporated into sandy soils at Fort Benning Military Reservation on two sites: a moderately degraded and a highly degraded soil. The waste material was applied at rates of 0, 17.9, 35.8, 71.6, and 143 Mg ha−1 and seeded with native prairie grasses to assess its effects on vegetation for two growing seasons, with an additional unseeded control treatment for comparison to natural recovery. The addition of uncomposted waste increased percent composition and basal cover of switchgrass (Panicum virgatum L.) at both sites and percent composition of big bluestem (Andropogon gerardii Vitman) at one site. Indiangrass [Sorghastrum nutans (L.) Nash] was negatively affected by the addition of the waste material at both sites. Biomass in the 143 Mg ha−1 treatment increased 4180% compared to the seeded control at the highly degraded site. Plant uptake of P and Na increased at both sites and an apparent Fe toxicity problem was alleviated at the highly disturbed site with increasing application rates. Because perennial grass establishment improved so dramatically with increasing application rates, land application of this uncomposted waste material could be considered a viable and beneficial alternative to current waste management practices for degraded Army lands.

Recovery of Rare Species: Case Study of the Masked Bobwhite

Recovery of threatened and endangered species under the Endangered Species Act (ESA) is accomplished via federally mandated recovery plans. Unfortunately, many recovery plans are limited in effectiveness because they suffer from various limitations; one of which is the lack of scientific data. Because recovery plans for endangered species are inherently plagued by lack of biological data of focal species, new approaches are warranted in recovery-plan development to use what little data are available more effectively. The use of academic–agency partnerships has been suggested as a means to accomplish this objective; academics contribute scientific knowledge, and agency personnel contribute federal regulation expertise. We used the masked bobwhite (Colinus virginianus ridgwayi), the only endangered quail in North America, as a case study to illustrate how such partnerships can be employed to incorporate the latest scientific knowledge into recovery planning. Because the case study of the masked bobwhite embodies many of the difficulties associated with endangered species recovery (e.g., lack of biological data, limited personnel, limited resources), our approach to linking biology, ecology, and management can serve as a general model for recovery planning of other endangered species. We began with a comprehensive review and synthesis of masked bobwhite literature. Based on this information, we then interpreted existing masked bobwhite knowledge within the context of current ecological understanding of quail demography. This integrated knowledge provided the foundation to discuss demographic, habitat, and genetic challenges facing masked bobwhites from the perspective of general population phenomena. Our synthesis led to the conclusions that masked bobwhite populations probably 1) experience chronic low reproduction resulting from living in a desert environment, 2) have not been negatively impacted by the historic conversion of grasslands to brushlands, and 3) have not been as detrimentally impacted as other avian species by the establishment of nonnative grasses within their range because these plants possess functional value for masked bobwhites. We also identified 4 immediate conservation needs: recognition of the significant role México possesses in masked bobwhite conservation and proactive involvement in international collaboration, the need for a reconnaissance of masked bobwhite habitat and populations in México, and the implementation and recognition of the critical role habitat management plays in masked bobwhite recovery efforts. These objectives must be accomplished if recovery is to succeed. Currently, the future of masked bobwhite is precarious. Masked bobwhite recovery inevitably will involve international collaboration as well as partnerships between agency biologists, private landowners, and research scientists.

EVALUATION OF EROSION CONTROL PRODUCTS WITH AND WITHOUT ADDED POLYACRYLAMIDE1

ABSTRACT: Polyacrylamide (PAM) has been demonstrated to greatly reduce erosion in furrow irrigation, but much less is known about its effectiveness on the much steeper slopes typical of construction sites. The purpose of this study was to determine if anionic PAM would enhance erosion control either alone on bare soil or in combination with four types of ground covers commonly used for grass establishment: straw, straw erosion control blanket (ECB), wood fiber, and mechanically bonded fiber matrix (MBFM). Tests were conducted under natural rainfall and vegetation on a 4 percent slope (bare soil, straw, ECB, and MBFM) or using a rainfall simulator (bare soil, straw, wood fiber, MBFM) on either 10 percent or 20 percent slope on three different soil substrates. All ground cover treatments were evaluated with and without PAM applied in solution at 19 kg/ha. The straw, ECB, and MBFM significantly reduced runoff volume, average turbidity, and total sediment lost over five rainfall events on the vegetated plots. The addition of PAM to ground covers only occasionally had significant effects on runoff parameters but did significantly increase vegetative coverage overall. The rainfall simulator tests produced similar results after four events, with the straw, wood fiber, and MBFM all having significantly lower turbidity than the bare soil. The PAM significantly reduced turbidity for both the first and second events but did not consistently improve runoff quality after multiple rainfall events for any ground cover‐soil combinations tested. Separate tests of PAM applied before or after straw did not indicate a clear advantage of either approach, but runoff turbidity was often significantly reduced with PAM, especially at the 20 percent slope. Turbidity reductions were attributed to flocculation of eroded sediment.