Perennial Grass Plants Research Articles

Effects of sowing method and competitor species and presence on Phalaris and Austrodanthonia establishment and persistence.

Two experiments were conducted on plots sown in autumn 1992, at Tamworth in northern New South Wales. The first compared the establishment of 3 perennial grasses when sown as monocultures or with competitors in either broadcast-sown swards or alternate row-sown plots. Sowing rate and species of competitor were also examined as factors affecting perennial grass establishment. Perennial grasses were Austrodanthonia richardsonii (synonym Danthonia richardsonii) cv. Taranna, A. bipartita (synonym D. linkii) cv. Bunderra, and Phalaris aquatica cv. Sirosa. Competitors were Trifolium subterraneum var. brachycalycinum cv. Clare, T. repens cv. Haifa, and Lolium rigidum cv. Wimmera. In spring 1992, competitors were removed from 144 of the 288 plots to prevent them from seeding. A second experiment compared the longer-term (1993–96) dry matter yield and persistence of these perennial grasses under continuous grazing in plots were the competitor was present in year 1 (1992) or in all years (1992–96). In spring 1992, mean dry matter yield of perennial grass was higher (P<0.001) in row-sown plots then those sown by broadcasting. Mean dry matter yield of perennial grass was lowest at low sowing rate, but not significantly different at medium and high sowing rates (about 350 kg DM/ha). Compared with the monocultures, the presence of a competitor reduced mean perennial grass dry matter yields by 48, 69 and 85%, respectively for white clover, subterranean clover and annual ryegrass. Perennial grass plant numbers were highest (P<0.001) in the medium and high sowing rates of the monocultures and in white clover competitor plots and lowest (P<0.001) in all broadcast-sown plots, where annual ryegrass was the competitor. By spring 1996, white clover and annual ryegrass had declined to a low level in the pasture in all plots and the only major competitor was subterranean clover (1200 kg DM/ha, 40% plant frequency). Mean dry matter yields were highest (P<0.001) for Sirosa in 1993, but with dry conditions in 1994 and continuous grazing they were highest for Bunderra in all other years. The implications of these data for devising sowing strategies to maximise the establishment of perennial grasses and their long-term persistence in this environment are discussed.

Shrub-Grassland Small Mammal and Vegetation Responses to Rest from Grazing

Between 1989-1991, I studied the effects of livestock grazing on vegetation and small mammals in semiarid shrub-grassland habitats of south-central Utah. Responses were measured at 2 spatial habitat scales; patches and macrohabitats. Patch-scale data were obtained from 4 small (<1 ha) livestock exclosures and nearby grazed areas. Macrohabitat-scale data were collected at 4 actively grazed sites and 4 comparable, excellent condition sites, ungrazed for 30+ years. Ungrazed patch and macrohabitat sites had more surface litter, greater perennial grass cover, and taller perennial grass plants, but treatment response varied among sites. Small mammal responses were apparent only at the macro-habitat scale, where ungrazed sites had 50% greater species richness and 80% higher abundance. Small mammal reproductive activity and biomass were not affected by rest from grazing at either scale. Small mammal community composition varied greatly among sites and within treatments. This variability has important implications for ecological monitoring efforts involving these species.

Spread of introduced Lehmann lovegrass Eragrostis lehmanniana Nees. in Southern Arizona, USA

Through seeding and subsequent spread, Lehmann lovegrass Eragrostis lehmanniana Nees. has transformed the structure and function of at least 145 000 ha of semi-desert grassland in southern Arizona since its introduction in 1932. Our study of its spread on the Santa Rita Experimental Range since 1954 showed that by 1989 it was present on >85% of 75 relatively widely dispersed non-seeded permanent plots and accounted for >40% of all perennial grass plants on these plots. In addition, it represented >50% of the perennial grass plants on sites <16 years after colonization, livestock grazing was not necessary for its spread, and it can account for >90% of the grass biomass and produce 2–4 times more biomass annually than native grass vegetation. In the future, strong consideration of these plant composition changes, and the likely decrease in wildlife diversity and increase in fire frequencies accompanying Lehmann lovegrass dominance, should be made before seeding the species.

Herbicide Treatment and Vegetation Response to Treatment of Mesquites in Southern New Mexico

Mesquite (Prosopk juliifrora) is a major unwanted plant in the Southwest This study evaluated the herbage responses obtained from various aerial applications of 2,4,5-T on mesquites in southem New Mexico. The dead plants on the various areas ranged from 7-64% of the mesquite. Yields of perennial grasses ranged from 3-1931 kg/ha on the untreated controls and 11-2696 kg/ha on the areas sprayed with 2,4,5-T. In dense stands of mesquite, about 30% of the mesquites must be kIIled before grass yields are significantly increased. There are an estimated 38 million ha of land infested with mesquite [Prosopis julifroru (Swartz) DC.] in the United States (Platt 1959). An estimated 4 million ha occur in New Mexico (Sampson and Schultz 1956). Although mesquite is an indigenous plant, it has invaded large areas and has become dominant on some of these in the last 100 years (Norris 1950, Wright 1960, Paulsen and Ares 1962, Buffington and Herbel 1965, York and DickPeddie 1969). The invasion and increase of mesquites have resulted in a decrease in cover and production of the perennial grass plants that once dominated these areas. As mesquites become established, an area devoid of herbaceous vegetation develops around the maturing mesquite plants. As the herbaceous cover is depleted wind erosion becomes more severe, particularly on sandy rangelands of the Southwest. Eventually, the “A” horizon and part of the “B” horizon is deposited around the mesquite or removed from the area entirely, resulting in a further decrease of the desirable perennial herbaceous plants and a build-up of sand dunes. Because of the competition for soil water by mesquite, few herbaceous plants become established on the eroded soils unless the mesquite is controlled. associations, the Upton-Simona association (shallower soils) and the Kermit-Maljamar-Berino association (Maker et al. 1970). The soils of the Jomada site are in the Simona-Harrisburg association (Bulloch and Neher 1980). These soils have a sandy surface that are quite susceptible to wind erosion. The surface relief is undulating or duned. The vegetation on the deeper sands in southeastern New Mexico is dominantly tall and mid-grasses, mesquite, sand shinnery oak [Quercus havurdi Rydb.)] and sand sagebrush [ArtemisiuJilifolia (Torr.)]. The more shallow soils support short and mid-grasses, mesquite, broom snakeweed [Xunthocephulum surothe (Pursh) Shinners] and some creosotebush [Lurreu tridentutu (DC.) Cov.]. The average annual precipitation varies from 258 mm at the Ochoa Weather Station in the southeast portion of the study area to 3 13 mm at Roswell. The study site on the Jornada Experimental Range is dominated by mesquite, broom snakeweed, and short and mid-grasses. The average precipitation is 225 mm.

Environmental Factors Influencing Semidesert Grassland Perennial Grass Demography

Long-term chart quadrat records from the Jornada Experimental Range in south-central New Mexico were photographed, the negatives analyzed with a flying-spot scanner, and the information converted for computer analyses. Some 35 quadrats with data from about 30 to 50 years duration were used giving records on the life-span of 12,437 perennial grass plants of seven species. Maximum life spans varied from 28 years for Bouteloua eripoda to only 7 years for Hilaria mutica. Mean life span for plants living at least 1 year varied from 3.8 to 3.0 years for these species. Average age-specific survival rates for seven perennial grasses increased from 0.39 at age 1 up to a maximum of 0.68 at age 7 and down to 0.48 at age 12. The level of grazing over the past years had little effect on plant survival, but cattle movement and trampling caused the death of some newly es- tablished grasses. A water-budget model produced results that could be readily interpreted in understanding plant survival. The relationship between the number of days of effective moisture in a given time period and the age-specific survival rates for each age class was pronounced. The period between the second and fourth age classes was most critical as regards availability of water. For newly established plants with shallow root systems, the precipitation of the immediate growing season was more important than precipitation for longer antecedent intervals. Continuous, reliable data, spanning long time periods are extremely rare for plant communities, particularly for herbaceous plants. Data on individual plants, necessary for examining many aspects of life history, are even more scarce. One of the major sources of such in- formation for herbaceous communities has been through chart quad- rat records in which permanently established quadrats are charted accurately over a period of years. Only limited amounts of such in- formation are reported in the literature. For humid and subhumid grasslands Harper (1960, 1967) has reported on demographic charac- teristics of Lemma minor and Salvina natans and Kerster (1968) reported on Liatris aspera. For semiarid and arid areas Nelson (1934)

SEASONAL GROWTH OF GRASS ROOTS

American Journal of BotanyVolume 28, Issue 6 p. 486-491 Article SEASONAL GROWTH OF GRASS ROOTS Irene H. Stuckey, Irene H. Stuckey Rhode Island Agricultural Experiment Station, Kingston, Rhode IslandSearch for more papers by this author Irene H. Stuckey, Irene H. Stuckey Rhode Island Agricultural Experiment Station, Kingston, Rhode IslandSearch for more papers by this author First published: 01 June 1941 https://doi.org/10.1002/j.1537-2197.1941.tb10966.xCitations: 37AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume28, Issue6June 1941Pages 486-491 RelatedInformation