Grass-like Species Research Articles

A roof of one's own: choice and access in global thatch sustainability

This paper examines global patterns of human-plant relationships related to the provisioning of roof thatch for human housing, encouraging greater understanding of the basic material and social conditions needed to support human well-being. I identify 205 species used for roof thatch in 60 countries around the world, with an additional 27 taxa identified to genus level. Grass-like species are by far the most common roof thatch material globally, followed by palm-like species (particularly in South America). However, this review was hindered by a persistent lack of attention to specific plant identities and their biological and ecological characteristics. Roof thatch is both a subsistence and commercial product, and is often considered an ecosystem service of secondary importance. As such, thatch has played a hidden role in the global economy to this point, and its cultural importance has been obscured. Mischaracterizing all subsistence use of thatch as poverty, without careful attention to human preferences for particular plant characteristics, is an over-simplification that ignores the complexity and dignity of land-based livelihoods. National and international markets, wealth, land ownership, skilled knowledge (both material and spiritual), skilled labor (both human and nonhuman), and new technologies all influence peoples’ equitable and sustainable access to roof thatch. This review demonstrates that access to preferred roof thatch is a critical aspect of human well-being, inextricably linked to the identities and sovereignty of rural and Indigenous communities. Long-term, place-based transdisciplinary work that seeks to understand and foster human-thatch relationships in specific contexts holds great potential for promoting future roof thatch sustainability in equitable ways.

Simulated herbicide spray retention of commonly managed invasive emergent aquatic macrophytes

AbstractInvasive emergent and floating macrophytes can have detrimental impacts on aquatic ecosystems. Management of these aquatic weeds frequently relies upon foliar application of aquatic herbicides. However, there is inherent variability of overspray (herbicide loss) for foliar applications into waters within and adjacent to the targeted treatment area. The spray retention (tracer dye captured) of four invasive broadleaf emergent species (water hyacinth, alligatorweed, creeping water primrose, and parrotfeather) and two emergent grass-like weeds (cattail and torpedograss) were evaluated. For all species, spray retention was simulated using foliar applications of rhodamine WT (RWT) dye as a herbicide surrogate under controlled mesocosm conditions. Spray retention of the broadleaf species was first evaluated using a CO2-pressurized spray chamber overtop dense vegetation growth or no plants (positive control) at a greenhouse (GH) scale. Broadleaf species and grass-like species were then evaluated in larger outdoor mesocosms (OM). These applications were made using a CO2-pressurized backpack sprayer. Evaluation metrics included species-wise canopy cover and height influence on in-water RWT concentration using image analysis and modeling techniques. Results indicated spray retention was greatest for water hyacinth (GH, 64.7 ± 7.4; OM, 76.1 ± 3.8). Spray retention values were similar among the three sprawling marginal species alligatorweed (GH, 37.5 ± 4.5; OM, 42 ± 5.7), creeping water primrose (GH, 54.9 ± 7.2; OM, 52.7 ± 5.7), and parrotfeather (GH, 48.2 ± 2.3; OM, 47.2 ± 3.5). Canopy cover and height were strongly correlated with spray retention for broadleaf species and less strongly correlated for grass-like species. Although torpedograss and cattail were similar in percent foliar coverage, they differed in percent spray retention (OM, 8.5± 2.3 and 28.9 ±4.1, respectively). The upright leaf architecture of the grass-like species likely influenced the lower spray retention values in comparison to the broadleaf species.

Responses of Ornamental Grass and Grasslike Plants to Saline Water Irrigation

Ornamental grasses are popular in urban landscapes in Utah and the Intermountain West United States, one of the driest and fastest growing regions in the United States. This experiment evaluated the responses of five ornamental grass species [blue grama (Bouteloua gracilis), indian sea oats (Chasmanthium latifolium), ‘Blue Dune’ sand ryegrass (Leymus arenarius), pink muhly grass (Muhlenbergia capillaris), ‘Foxtrot’ fountain grass (Pennisetum alopecuroides)] and two ornamental grasslike species [fox sedge (Carex vulpinoidea), common rush (Juncus effusus)] to saline irrigation water in a greenhouse. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m–1 (control) or saline solutions at an EC of 5.0 or 10.0 dS·m–1. At the first harvest (9 weeks after the initiation of treatment), sand ryegrass, pink muhly grass, and fountain grass irrigated with solutions at an EC of 5.0 and 10 dS·m–1 had good visual quality with no or minimal foliar salt damage; however, the remaining species exhibited slight or moderate foliar salt damage. There were no significant differences in shoot dry weight (DW) among treatments within any species, except fox sedge and fountain grass. At the second harvest (18 weeks after the initiation of treatment), sand ryegrass, pink muhly grass, and fountain grass still had no or minimal foliar salt damage, and indian sea oats and fox sedge exhibited slight or moderate foliar salt damage. Compared with the control, all species irrigated with solutions at an EC of 10.0 dS·m–1 had reduced shoot DWs with the exception of blue grama. However, only common rush and pink muhly grass irrigated with solutions at an EC of 5.0 dS·m–1 had lower shoot DWs than the control. These results demonstrated that seven ornamental grass or grasslike species had a very strong tolerance to the salinity levels used in the 4-month experiment. Although plant growth was inhibited as a result of saline irrigation, plant visual quality of sand ryegrass, pink muhly grass, and fountain grass was still acceptable. These three species appear to be more suitable for landscapes in which saline irrigation water is used. Further research is needed to evaluate more ornamental grasses for landscapes in salt-prone areas and nearby coastal regions.

Guanaco’s diet and forage preferences in Nothofagus forest environments of Tierra del Fuego, Argentina

Aim of study: Guanaco (Lama guanicoe Müller), is a South American native ungulate widely distributed in Patagonia, which in the island of Tierra del Fuego (TF), extends its habitat into Nothofagus spp. forests. Within these forests, guanacos consume lenga (Nothofagus pumilio) leaves and twigs, and other understory species. The aim of this work was to determine: 1) the spring and summer diet of free ranging guanacos, and 2) which plants, grown in the forest understory, guanacos do prefer, or avoid, in these seasons of great forage abundance.Area of study: Tierra del Fuego (Argentina), on three representative areas which combined Nothofagus forests and adjacent meadows (vegas).Material and Methods: Guanacos’ diet was determined by comparing epidermal and non-epidermal plant fragments with micro-histological analyses of feces. The analysis was made from composite samples of fresh feces, collected at the seasons of maximum forage productivity (spring and summer).Main results: During spring, 48% of guanacos’ diet was composed of lenga leaves, 30% of grass-like species, 15% of grasses, and less than 7% of herbs, shrubs, and lichens. In summer, 40% of the diet was composed of grasses, 30% of lenga leaves, 25% of grass-like species and the rest corresponded to herbs, shrubs, and lichens. Within the forest understory, guanaco selected lenga leaves and twigs, grass species were consumed according to their availability (or sometimes rejected), while other herbs were not consumed at all.Research highlights: Guanacos’ consumption preference for lenga, even considering the high availability of other forages, could adversely affect forest regeneration.

Phytoremediation potential of indigenous Ghanaian grass and grass-like species grown on used motor oil contaminated soils

This study investigated the ability of Bothriochloa bladhii (Retz.) S.T. Blake (Poaceae), Cyperus ligularis L. (Cyperaceae), Commelina erecta L. (Commelinaceae), Mariscus umbellatus (Rottb.) Vahl (Cyperaceae), Fimbistylis miliacea L. (Cyperaceae) and Torulinium odoratum L. (Cyperaceae) to clean up various levels of used motor oil (UMO) contaminated soils. The plants were grown in 2 kg garden soils treated to 0%, 1%, 5% and 10% levels of UMO contamination. The plant growth parameters, chlorophyll contents and dry weight of test plants were measured. The phytoremediation ability of these test plants were assessed by measuring the uptake of hydrocarbons in terms of total hydrocarbon content (THC) as well as their percentage degradation values. There was significant ( P < 0.05) reduction in leaf chlorophyll contents and dry weights of the test plant species planted in UMO contaminated soils. THC as well as the percentage uptake (or degradation) of hydrocarbons were both lowest in C. ligularis but highest in T. odoratum in all cases. The phytoremediation potential of test plants was highest in soils contaminated with 5% UMO. Based on the results of this study, all test plants with the exception of C. ligularis were potentially capable of undertaking phytoremediation. However, B. bladhii and T. odoratum proved most effective in the uptake and degradation of UMO.

The Influence of Cow Age on Botanical Composition of Diets in Mountain Riparian Areas in Eastern Oregon of the United States

&lt;p&gt;The objective of this study was to evaluate the effect of cow age on botanical composition of diets in mountain riparian areas. Treatments consisted of 30 first-calf heifers, and 30 mature cows randomly assigned to four pastures (2 pastures/treatment, average 21.5 ha) in a 2-year study with a cross-over design. Botanical composition of diets was determined in fecal samples obtained from 10 animals in each treatment (5 per pasture) on the fourth week of 35 to 42-days grazing periods using the microhistological technique. Crude protein (CP) content and &lt;em&gt;in vitro&lt;/em&gt; dry matter digestibility (IVDMD) were determined, and correction factors were calculated for 22 major plant species. In digested samples, grasses were overestimated, whereas, all forbs but northern bedstraw (&lt;em&gt;Galium boreale &lt;/em&gt;L.), were underestimated, and all shrub species were overestimated except common snowberry (&lt;em&gt;Symphoricarpos albus &lt;/em&gt;L.). Ponderosa pine (&lt;em&gt;Pinus ponderosa &lt;/em&gt;Dougl.) was highly overestimated after digestion. There was no difference between cattle age class in the total number of plant species found in the diets (&lt;em&gt;p&lt;/em&gt; &amp;gt; 0.10) averaging in 41 species. Most individual grass and grasslike species made up more than 5% of the diets, while all individual forb, shrub, and tree species were minor components, not exceeding 5%, except ponderosa pine. Western wheatgrass (&lt;em&gt;Agropyron smithii &lt;/em&gt;Rybd.) and tufted hairgrass (&lt;em&gt;Deschampsia caespitosa &lt;/em&gt;(L.) Beauv.) accounted for over 10% of the diets. Heifers consumed more (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.05) grasses and fewer (&lt;em&gt;p &lt;/em&gt;&amp;lt; 0.10) shrubs and trees compared to mature cows. The diet of heifers contained more western wheatgrass, Baltic rush (&lt;em&gt;Juncus balticus &lt;/em&gt;Willd.), and pinegrass (&lt;em&gt;Calamagrostis rubescens &lt;/em&gt;Buckl.) (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.10), but less Kentucky bluegrass (&lt;em&gt;Poa pratensis &lt;/em&gt;L.) (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.01), than the diet of mature cows. The proportion of ponderosa pine needles was higher in the diet of mature cows (&lt;em&gt;p&lt;/em&gt; &amp;lt; 0.10), than in the diet of first calf heifers. In summary, mature cows appeared to have selected a diet that contained less grasses and more shrubs and trees compared to younger cows.&lt;/p&gt;

What do domestic livestock eat in northern Patagonian rangelands?

The Patagonian rangelands are dominated by steppes interspersed with meadows (locally called mallines), which are small but permanently humid areas, characterised by high spring–summer quality and productivity of grasses and grasslikes. The region’s main economic activity is sheep ranching, either alone or mixed with goats and/or cattle, using horses as transportation animals. Overstocking has been signalled as one of the causes of rangeland degradation in this region. Knowledge of botanical composition of livestock diets provides valuable information helping in the design of management strategies to improve or maintain the forage resource. With this objective we studied the dietary botanical composition of domestic livestock on Patagonian ranches with and without mallines, at different seasons. It was found that the differences between diets of the same herbivore species on ranches with and without mallines were greater than the differences among the diets of the different herbivores species grazing in the same type of ranch. Grasses were the forage class most consumed by livestock in 76% of ranches without mallines and in 38% of the diets of ranches with them, with Stipa spp. being the main species consumed. Grass-like species were important in ranches with mallines, specially Juncus spp., and woody plants (Chuquiraga spp. as the most consumed) in ranches without mallines. Forbs hardly exceeded 10% in some spring diets of sheep, at both ranch types. Grasslikes constituted the major component of the spring and summer cattle diets, and constituted one-third of winter diets. For the rest of the herbivores studied, this forage class was important in spring–summer diets, but insignificant in the winter samples. Goats showed a greater use of the shrub in the less productive ranches and they were the most important consumers of shrubs on ranches with mallines during winter, which is the critical season of forage production. We conclude that the presence of mallines strongly condition the diet composition of the studied domestic herbivores. And, since the use of forage classes is different between these animal species, given a ranch type, the replacement of single-species grazing by mixed grazing can achieve the optimal possible use of the Patagonian rangelands.

Herbaceous Plants and Grasses in a Mountain Longleaf Pine Forest Undergoing Restoration: A Survey and Comparative Study

The Berry College Longleaf Pine Management Area consists of old-growth fire-suppressed mountain Pinus palustris (Longleaf Pine) stands embedded within an encroaching matrix of mixed pines and hardwoods. Since 2001, portions of this area have been subjected to restoration efforts involving logging followed by burning, foliar herbicide application, and planting, as well as burning and hardwood control using herbicides in unlogged old-growth stands. To document the herbaceous plants and grasses of this site and to begin to address questions concerning the short-term impacts of management practices on these species, flowering specimens were systematically collected in managed and unmanaged stands in 2008 and 2009. We recorded 201 species in 35 families, including 70 species of Asteraceae, 35 species of Poaceae, 17 species of Fabaceae, and 10 grass-like species other than Poaceae (Cyperaceae, Iridaceae, and Juncaceae). Native herbaceous plants most commonly found included: Houstonia caerulea, Hypoxis hirsuta, Solidago odora, Oxalis stricta, Coreopsis major, Hypericum hypericoides, Lespedeza procumbens, Hieracium venosum, and Packera paupercula. While only 14 species were found in unmanaged old growth, 127 were found in managed old growth, and 167 in logged areas. Fire suppressed old-growth mountain Longleaf Pine forests are generally virtually devoid of understory plant diversity; these results suggest that reduction in canopy density and leaf litter can substantially recover herbaceous and grass species diversity. However, the extent to which understory diversity can be fully recovered in any specific site remains in question, particularly if local propagule sources have vanished during the period of fire suppression. A comparison with historical species lists at our site, and with other mountain Longleaf Pine forests in various stages of fire maintenance, is presented to help define characteristic understory species for mountain Longleaf Pine forests.

The Nearctic-Caribbean species Leptotrachelus dorsalis (Fabricius, 1801): Larval descriptions with a diagnosis of immature Ctenodactylini and natural history notes on the genus and tribe (Coleoptera, Carabidae)

Adults and larvae of Leptotrachelus dorsalis (Fabricius), the Sugarcane Savior Beetle, live in association with grasses, the larvae in the appressed leaf axils. Both adult and larval Leptotrachelus dorsalis eat larvae of the Sugarcane Borer, Diatraea saccharalis (Fabricius), and perhaps other insects living in the confines of the leaf sheaths of that and other grass-like species. The geographic range of Leptotrachelus dorsalis extends from Kansas in the west to the Atlantic seaboard, north as far as Ontario, Canada and south to Cuba; it is an eastern species of North America and the Caribbean. Larval character attributes that are shared with a related ctenodactyline, Askalaphium depressum (Bates), provide a preliminary basis for characterization of the immatures of tribe Ctenodactylini.

An international terminology for grazing lands and grazing animals

Preface 2 Members of the committee 3 Acknowledgements 3 An International Terminology for Grazing Lands and Grazing Animals 1. Grazing land terms 4 2. Vegetation: descriptive terms 6 3. Forage growth and harvest 8 4. Forage nutritive value and intake 9 5. Management of grazing lands 12 6. Land–forage–animal relationships 15 7. Stocking methods 16 References 18 Appendix I. References and additional information for selected terms 21

Metabolite fingerprint of “capim dourado” (Syngonanthus nitens), a basis of Brazilian handcrafts

Syngonanthus nitens is a grass-like species, whose flower stems assume a beautiful golden colour when dried, hence their common name “capim dourado”. This plant represents an important source of income for rural communities, especially in Jalapão region, being the scapes used in the craft industry to make, together with buriti palm strips, traditional handcrafts from their coils. Therefore, considering that scapes and not flowerheads are used, we carried out an analytical study to define the metabolite fingerprint of both S. nitens parts, with the aim, on one hand, to identify the molecules responsible for the characteristic golden colour of the capim dourado herb and, on the other hand, to identify the occurrence of interesting constituents in S. nitens flowerheads to increase the value of this part of the plant, considered a waste matter of golden grass handcrafts. Therefore an HPLC–ESI-MSn method, based on high-performance liquid chromatography coupled to electrospray negative ionization multistage ion trap mass spectrometry, was developed to rapidly identify and guide the isolation of the secondary metabolites occurring in flowers and scapes. On the basis of the on-line HPLC–ESI-MSn screening, 17 compounds, including 6 new molecules, were isolated, and their structures were unambiguously elucidated by NMR spectroscopic data.

Ceropegia thailandica (Asclepiadoideae-Ceropegieae), a spectacular new Thai species

A new species from Thailand, Ceropegia thailandica Meve (Apocynaceae-Asclepiadoideae-Ceropegieae) is described and illustrated. The new species is related to the Indian C. spiralis, and belongs to a group of tuberous, non-twining, grass-like species that are widespread on the Indian subcontinent. The single, exeedingly long-stalked flowers with ovoid basal inflations and very long, tightly spiralled corolla lobes, leaving only small and characteristically auriculate openings for insect visitors, make the new species an unrivalled appearance in Ceropegia.

Do graminoid and woody invaders have different effects on native plant functional groups?

Summary 1 While there are numerous studies of impacts by individual invader species, there are few syntheses of invader impacts on plant community structure and composition. We sought to identify native plant functional groups (PFGs) which are under-represented in post-invaded compared with non-invaded environments to determine whether different invader morphologies consistently suppressed native species richness within particular PFGs. 2 We conducted a meta-analysis of 20 international studies to analyse the effects of graminoid (grass and grass-like species) and woody (shrub or tree species) invaders on species richness within growth form, longevity and seed mass native PFGs. 3 Graminoid and woody invaders could not be distinguished by their effects on native PFGs: in most cases, native PFGs were negatively affected by both graminoid and woody invaders. However, within the growth form classification, we found that negative invader effects were greater for native graminoid than tree species. Perennial rather than short-lived species appeared more affected by invasion (particularly graminoid invasion). Species with small seed masses appeared more negatively affected than those with large seed masses, particularly by graminoid invaders. 4 Synthesis and applications. Despite different morphologies of graminoid and woody invaders, they had similar negative effects on species richness within a range of native plant functional groups (PFGs). Further, the response of many PFGs to graminoid invaders in particular was highly variable. In consequence, managers cannot rely on invader morphology to distinguish impacts and prioritize control efforts. While graminoid and woody invaders had similar impacts, they had particularly adverse effects on small herbaceous (especially graminoid) and perennial species. Managers should focus monitoring activities on these potentially under-represented PFGs following control of both woody and graminoid invaders. Native species belonging to herbaceous and perennial PFGs may require focused reintroduction following control efforts.

Ornamental Landscape Performance of Native and Nonnative Grasses under Low-input Conditions

Full sun trial gardens (full sun) were established at Leon County (LC) and Santa Rosa County (SRC), Florida, to evaluate the effect of site on horticultural performance traits pertinent to landscape use (long-term growth, flowering, vigor, overall quality, and survival) of native and nonnative warm season grasses when grown under low-input landscape conditions over a 3-year period. The gardens contained landscape fabric- (LC) or plastic (SRC)-covered rows, with the synthetic mulch at each site covered by 4 inches of hardwood chip mulch. Fifteen native and eight nonnative grass species, and cultivars were evaluated as were the two grass-like species black flowering sedge (Carex nigra) and narrowleaf silkgrass (Pityopsis graminifolia), a native dicot with grass-like foliage. Many of the native species were derived from seeds or plants collected from naturally occurring populations in Florida, and other species or cultivars were obtained from commercial sources. Based on quality ratings and survival, a majority of the species and cultivars were rated as at least being marginally acceptable for 2 years or more, but only six species and cultivars were rated as excellent or good over all 3 years. Four of these six species were native, with 100% survival at both sites occurring only for purpletop tridens (Tridens flavus). The other three native species, gulf hairawn muhly, (Muhlenbergia capillaris var. filipes), ‘Alamo’ switchgrass (Panicum virgatum), and indian woodoats (Chasmanthium latifolium) had high rates of survival. Porcupine grass (Miscanthus sinensis ‘Strictus’) and ‘Cabaret’ silver grass (M. sinensis ssp. condensatus) were the only two nonnative species demonstrating potential for long-term performance in a low-input landscape at both sites. Three of the four cultivars of miscanthus (Miscanthus spp.) survived the entire evaluation period in SRC, while two cultivars suffered losses only in LC, demonstrating the importance of site effects on the long-term performance of individual species or cultivars of grasses. Chalky bluestem (Andropogon capillipes) (Orange County, FL), sand lovegrass (Eragrostis trichoides), giant silver grass (Miscanthus ×giganteus), and bamboo muhly (Muhlenbergia dumosa) each survived 3 years at one site but only 1 year at the other site. Pineland threeawn (wiregrass) (Aristida stricta), ‘Red Baron’ cogon grass (japanese blood grass) (Imperata cylindrical), ‘Hameln’ fountain grass (Pennisetum alopecuroides), black flowering fountain grass (P. alopecuroides ‘Moudry’), and ‘Feesey Form’ ribbon grass (Phalaris arundinaceae) were categorized as marginal for low-input landscapes and could only be considered short-term perennials under the conditions of this test. ‘Morning Light’ silver grass (M. sinensis), coastal bluestem (Schizachyrium maritimum), and ‘Lometa’ indiangrass (Sorghastrum nutans) had good 2-year landscape performance and survived at least 2 years at both sites. Bigtop lovegrass (Eragrostis hirsuta), silver plumegrass (Saccharum alopecuroides), and lopsided indiangrass (Sorghastrum secundum) were categorized as having excellent 1-year landscape performance and have potential for short-term performance under low-input conditions. Chalky bluestem (Andropogon capillipes) (SRC), black flowering sedge, ‘Heavy Metal’ switchgrass (Panicum virgatum), and narrowleaf silkgrass were categorized as having good 1-year landscape performance.

Weed cover in hybrid poplar ( Populus) plantations on Quebec forest soils under different lime treatments

Fast-growing trees such as hybrid poplars ( Populus) have the potential to decrease rotation length (time to harvest) and thus produce wood products more quickly from smaller areas of land. Several forest companies in Quebec currently plant hybrid poplar on formerly logged forest sites, rather than on agricultural land as is more common elsewhere. The forest sites often have acidic soils, and lime addition has been proposed to improve hybrid poplar growth. In addition, forest sites present challenges with regard to control of competitive vegetation, particularly in jurisdictions such as Quebec where use of herbicides in forests is banned or restricted. Our study investigated the impacts of lime treatments (0, 2000 or 4000 kg ha −1) on non-crop vegetation on forest sites planted to hybrid poplar. Soil and plant data were obtained from 270 experimental plots in southern Quebec, divided between two study sites. Soil pH before treatment ranged from 3.9 to 5.7, with means of 4.7 and 5.0, respectively, at the two sites. Weed data were obtained 2 years after treatment from 20 microsites per plot (5400 in total). Parameters included total cover by all weeds combined and cover by particular subcategories. Hybrid poplar growth and nutrition were also measured. Lime increased soil pH, soil exchangeable calcium and hybrid poplar growth. Total weed cover did not differ significantly by lime treatment, nor did cover by major subgroups such as grasses and grasslike plants, forbs or woody species. Soil pH (both pre- and post-treatment) was positively correlated with post-treatment weed height, grass cover, forb cover and hybrid poplar growth. It was negatively correlated with cover by woody non-crop plants. The relationships between pH and particular weed groups suggest that more intensive liming, and/or greater time since lime application, could favour certain vegetation types over others (e.g., grasses and grasslike species over woody non-crop plants), although no large-scale shifts were detectable within the scope of our study.

Selective herbivory by mammals on 19 species planted at two densities

The impact of mammalian herbivory, particularly macropods, upon seedling establishment in a post-fire environment was studied experimentally at Whiteman Park Reserve, Perth, Western Australia. Nineteen plant species of contrasting morphology and chemistry were established at low and high densities in protective exclosures, and half of the plants later exposed to herbivores. After one year of exposure, 16 species showed evidence of greater mortality and/or reduced shoot mass due to mammal herbivory. Two species had reduced shoot mass at high density (competition) and two had the reverse (facilitation), both annulled in the presence of herbivores due to poor growth at both densities. There was no preference by herbivores for high over low density plots. A general preference (high percentage plants eaten, large difference between biomass inside and outside exclosures) for species high in K, N or P and leaf mass: area, and low in initial shoot mass, spinescence, moisture and height was evident from principal components and canonical variates analyses. Grass-like species were more vulnerable to herbivory than seedlings of shrubs.

Planting density effects and selective herbivory by kangaroos on species used in restoring forest communities

We used exclosures to assess 16 plant species for the effects of planting density and kangaroo herbivory at two recently rehabilitated bauxite mines in eucalypt forests of southwestern Australia. Despite significant climate differences the browsing trends at both mines were similar. By the first harvest (2 months after establishment) there were significant reductions in shoot mass and survival for five species exposed to browsing, while plants at high density were 25% smaller than widely spaced plants. By the second harvest (10 months), this increased to 7 of the 16 species, while spacing effects diminished. We showed the effects of herbivory to be profound, while interactions at the seedling stage were minimal. Species with higher levels of protein were not favoured, while those highest in tannins, salts and sulfur were usually avoided. As with other medium-sized herbivores, plant architecture (leaf shape) was a prominent selective agent: in this case, grasses and grasslike species were most likely to be selected and adversely affected, though some dicots were readily consumed. Browsing optimization (benefiting from herbivory) was identified in three native legumes with high growth rates. In our study, herbivore choice often equated to herbivore impact; however, future planting in rehabilitated areas should allow for resilience and compensation by some species. We offer suggestions aimed at broad silviculture practices: we showed that some species benefit from herbivory and suggest these be identified by land managers as they may serve as diversions for nearby rare or vulnerable species.

Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community

Evapotranspiration rates and the ground water component of evapotranspiration at a site in Colorado's San Luis Valley that is dominated by shrubby phreatophytes (greasewood and rabbitbrush) were compared before and after a water table drawdown. Evapotranspiration (ET) rates at the site were first measured in 1985–1987 (pre-drawdown) when the mean water table depth was 0.92 m. Regional ground water pumping has since lowered the water table by 1.58 m, to a mean of 2.50 m. We measured ET at the same site in 1999–2003 (post-drawdown), and assessed physical and biological factors affecting the response of ET to water table drawdown. Vegetation changed markedly from the pre-drawdown to the post-drawdown period as phreatophytic shrubs invaded former wetland areas, and wetland grasses and grass-like species decreased. Lowering the water table reduced estimated total annual ET from a mean of 409.0 to 278.0 mm, a decrease of 32%, and the ground water component of ET (ET g), from a mean of 226.6 to 86.5 mm, a decrease of 62%. Two water table depth/ET models that have been used in the San Luis Valley overestimated the reduction in ET g due to lowering the water table by as much as 253%. While our results corroborate the generally observed negative correlation between ET rates and water table depth, they demonstrate that specific models to estimate ET as a function of water table depth, if not verified, may be prone to large errors. Both the water table drawdown and the vegetation change are continuing 20 years after the drawdown began, and it is unclear how site ET rates and processes will differ after the water table has stabilized and vegetation has adjusted to the new site hydrologic conditions.

Biological Control of Leafy Spurge with Introduced Flea Beetles (Aphthona spp.)

Astract Flea beetles ( Aphthona spp.) were introduced into leafy spurge (E u p h o r b i a e s u l a L.)-infested rangeland in east-central North Dakota. The study objectives were to evaluate the effects of the introduced insects on leafy spurge cover, density, and yield, and grass and grass-like yield of associated plant communities. A p h t h o n a spp. were released in 1988 and 1989 at 2 sites near Valley City, N.D. Aboveground vegetative sampling for leafy spurge cover, density and yield, and grass and grass-like yield was conducted between 1993 and 1995. Belowground sampling of root density, dry weight and root buds was conducted between the release date and 1995. A p h t h o n a spp. reduced aboveground cover, density and yield of leafy spurge and increased yield of grass and grass-like species. Leafy spurge root density, weight, and number of root buds decreased on insect release sites between release dates and 1995. Reduced stem density of leafy spurge and increased grass and grass-like yield, should enhance cattle use and production from these sites.

Biological control of leafy spurge with introduced flea beetles (Aphthona spp.)

Flea beetles (Aphthona spp.) were introduced into leafy spurge (Euphorbia esula L.)-infested rangeland in east-central North Dakota. The study objectives were to evaluate the effects of the introduced insects on leafy spurge cover, density, and yield, and grass and grass-like yield of associated plant communities. Aphthona spp. were released in 1988 and 1989 at 2 sites near Valley City, N.D. Aboveground vegetative sampling for leafy spurge cover, density and yield, and grass and grass-like yield was conducted between 1993 and 1995. Belowground sampling of root density, dry weight and root buds was conducted between the release date and 1995. Aphthona spp. reduced aboveground cover, density and yield of leafy spurge and increased yield of grass and grass-like species. Leafy spurge root density, weight, and number of root buds decreased on insect release sites between release dates and 1995. Reduced stem density of leafy spurge and increased grass and grass-like yield, should enhance cattle use and production from these sites.