Plant Pathology Commons^™

Valuing The Pasture Resource - Importance Of Perennials In Higher Rainfall Regions Of South Eastern Australia, P. M. Dowling, R. E. Jones, David R. Kemp, D. L. Michalk

IGC Proceedings (1977-2023)

The premature decline of perennial grass based pastures in southern temperate Australia results in poor productivity and unstable pastures that allow invasion by less desirable weedy species and the potential for soil degradation. The loss of perennial species is attributed to overgrazing arising from an undervaluation of the pasture resource. Resowing pastures is largely uneconomic so maintenance of, or increasing the perennial, is dependent on improved grazing and pasture management practices. A key to changing perceptions is valuing the true worth of the perennial component. Results are presented from a model that takes into account the seasonality of production of …

Using ‘Traps’ (Transect Recording And Processing System) In Woody Weed Control Studies In Australia, P. V. Back

IGC Proceedings (1977-2023)

The ‘TRAPS’ (Transect Recording And Processing System) methodology has proven to be a powerful and versatile tool for studying the effects of various woody weed control strategies in studies carried out in Queensland, Australia. ‘TRAPS’ allows the tracking of individual woody plants even when destructive control techniques such as bulldozing, ploughing and burning are used. This methodology also allows the investigator to discriminate between plants present before any treatment is imposed and plants recruited after the treatment.

Importance Of Haresfoot Clover (Trifolium Arvense) As A Nitrogen Fixer In Semi-Arid Grasslands Of New Zealand, C. C. Boswell, W. L. Lowther, P. R. Espie

IGC Proceedings (1977-2023)

The aim of the study was to determine the distribution of annual haresfoot clover (Trifolium arvense) in a depleted indigenous short tussock grassland catchment in the dry subhumid MacKenzie Basin, South Island, New Zealand. Haresfoot clover was present on all landscapes, and widely distributed on lower sunny aspects, suggesting that it is an important component of the nitrogen cycle in these environments even in the absence of fertiliser application. The study was conducted during an atypically moist summer when a bloom of the annual clover occurred. Nitrogen inputs will vary with landscape and spring/summer rainfall and it is …

The Future For Savanna And Tropical Grasslands: A Latin American Perspective, R. R. Vera

IGC Proceedings (1977-2023)

The objective of the paper is to briefly review the main trends in the tropical lowlands of Latin America and the Caribbean (LAC) with particular emphasis in the neotropical savannas. These tropical native grasslands cover occupy approximately 210 million hectares, and constitute major portions of the territory of Bolivia, Brazil, Colombia, Guyana and Venezuela. Many analysts consider that intensification of their use is a valid alternative to the expansion of the livestock and crop industries into the rainforest.

The evidence reviewed shows that since the late 1980s, the LAC agricultural sector has shown dynamism not seen for many years. Despite …

Ecophysiology And Management Response Of The Subtropical Grasslands Of Southern South America, E. J. Berretta

IGC Proceedings (1977-2023)

The subtropical grasslands of Southern South America (campos) are located approximately in the range of 24° S to 37° S latitude. These grasslands are dominated by C₃ and C₄ grasses, and in a lesser extent to herbaceous plants, shrubs and dispersed trees, with some exceptions in particular regions. Previous to the introduction of large herbivores, at the beginning of the XVII century, like cattle and horses, shrubs and tall grasses dominated the vegetation. Then, associated with greater grazing pressure and partially due to fire, the original campos are maintained, actually in a pseudo-climax herbaceous phase. These native communities …

Goats To Control The Encroachment Of Undesirable Brush And Woody Species In Cattle Pastures, J-M. Luginbuhl, J. T. Green Jr., M. H. Poore, A. C. Conrad

IGC Proceedings (1977-2023)

Field studies were initiated in an abandoned, overgrown 8.4 ha orchard left untouched for 15 years to evaluate the effectiveness of using goats (Capra hircus hircus) to manage undesirable vegetation. Goats alone (G: 30 does/ha) or cattle (Bos taurus) with goats (GC:17 does/ha and 3 steers/ha) were mob-grazed twice a year during four grazing seasons. Multiflora rose (Rosa multiflora Thunb.) canopy area decreased from 12 to 2.5 m² in grazed pastures and multiflora rose live canes were 100% in the control, 0% in G, and only 8% in GC at the completion of the …

Herbaceous Vegetation Dynamic After Cut And Burn Shrub Plants In Southern Brazil, A. M. Girardi-Deiro, M. L. Porto, J. Riboldi

IGC Proceedings (1977-2023)

A savanna area at "Serra do Sudeste" in southern Brazil, was studied during four years to evaluate the influence of cutting and burning shrub plants on dynamic of herbaceous vegetation. The cover of each species in 44 permanent quadrats (0,25 m²) and in each area (cut and burned) was evaluated. The results suggested that grasses and legumes were favored by cutting shrub plants. Burning favored forbs in the first years after disturbance and retarded the development of native forage species desirable for grazing.

Characterization Of Forage Selected By Cattle On Communal Range In Manhiça, Mozambique, O. Faftine, A. Alage, J. P. Muir

IGC Proceedings (1977-2023)

Forage selection by 10 cattle herds was observed monthly over 2 years on a communal rangeland. Plants grazed were hand-plucked as representative of both species and plant portions being cropped by cattle. Herds were led to green pasture year-round. Nutrient concentration of species and plant portions selected by cattle indicated adequate crude protein and calcium but phosphorus deficiency during the dry season. Well-drained escarpments and uplands were more important during the rains while upland depressions and the Nkomati valley were essential for adequate forage intake during the dry seasons.

Deforestation For Pasture Development – Has It Been Worth It?, W. H. Burrows

IGC Proceedings (1977-2023)

Differing scenarios leading to deforestation for pasture development in savanna (woodland) and closed forest communities in the tropics – sub-tropics are compared and contrasted. Australian and Brazilian examples are highlighted. No simple answer is given to the question of whether deforestation for pasture development has been worth it, since both commercial and non-commercial values have equal validity and need to be taken into account. These issues are addressed in the context of land assigned by governments for agricultural purposes. It is concluded that technology and ecological understanding are now available to maintain sustainable production from converted forest systems. However emphasis …

Back To The Future – Pastoral Land Use In A Forest Land – Sustainability Challenges For The 21St Century, J. Morgan Williams

IGC Proceedings (1977-2023)

To contribute meaningfully to a session entitled “Deforestation” with a proposed paper title of “Trees in Pastoral Zones; Landuse Standards in the 21^st Century” necessitates I carefully define the scope of my contribution. My paper will draw on my experiences as an ecologist working in the pastoral lands of New Zealand in roles that have led me to delve increasingly into what constitutes sustainability (of people, land and economy) for a tiny multicultural nation maturing amidst the remnants of a unique Gondwanaland ecosystem. As New Zealand’s Parliamentary Commissioner for the Environment (PCE) I now examine a very wide range …

Carbon Accumulation In Soils Under Brachiaria Pastures In The Atlantic Forest Region Of The South Of Bahia, Brazil, R. M. Tarré, R. Macedo, R. B. Cantarutti, C. De P. Rezende, J. M. Pereira, E. Ferreira, B. J. R. Alves, S. Urquiaga, R. M. Boddey

IGC Proceedings (1977-2023)

The objective of this study was to investigate the change in carbon stocks in soil following deforestation of the Atlantic forest in the South of Bahia State (Brazil) and replacement with productive pastures of Brachiaria humidicola either in monoculture or with the introduction of the forage legume Desmodium ovalifolium. Carbon stocks in the 0-30 cm layer were 44.5 Mg ha^-1 under the original forest and found to be approximately 42 Mg ha^-1 C 10 years later. At this time pastures of B. humidicola with or without the presence of D. ovalifolium were formed and grazed continuously for …

Potential Role Of Native Bush In The Chaco For Mitigation Of Dryland Salinity In Grassland, A. Glatzle, R. Schultze-Kraft, R. Mitlöhner

IGC Proceedings (1977-2023)

There is a zone of some 3.000.000 ha with an elevated dryland salinity risk in the Paraguayan Chaco due to a shallow saline ground water table. Evidence is shown of the crucial role native bush seems to play in keeping the water table at a low level and reducing therefore the risk of soil salinisation. In this paper a planned field experiment is outlined to define the tolerable level of deforestation and pasture establishment for a sylvopastoral production system in the Chacoan zone prone to dryland salinity.

Initial Effects Of Deforestation On Herbaceous Species Composition In Grassy Woodlands Of The Northern Tablelands, Nsw Australia, Chris R. Chilcott, N. Reid, R. D. B. Whalley

IGC Proceedings (1977-2023)

Limited information on the initial effects of clearing and thinning on herbaceous vegetation of grassy temperate eucalyptus forests exists. The aim of this investigation is to study the initial changes in species composition following clearing and thinning. A deforestation experiment was established where clearing, thinning of 50% of canopy cover and control treatments were established. In the open-forests, patterns in herbaceous species composition were strongly influenced by the presence of trees, with weeping wheat grass (Microlaena stipoides) dominant, whereas wiregrass (Aristida ramosa) dominated interspaces and canopy gaps. Immediately following clearing, significant changes in the herbaceous species …

The Influence Of Large Animal Diversity In Grazed Ecosystems, M. G. Murray, D. R. Baird

IGC Proceedings (1977-2023)

Field observations in the Serengeti National Park, Tanzania have revealed several modes of grazing system, including migration, sustained-yield grazing and grazing succession which contribute on the one hand to ecological separation of herbivores by habitat choice, but on the other hand to positive association of species on wet season pastures known as hot spots. Drawing from results of experimental field studies, we consider what is known about resource competition and facilitation, the two key ecological processes underlying these grazing systems, and specify the shape of the relationship between species richness and pasture height that is predicted depending on which process …

Grassland Use And Plant Diversity In Grazed Ecosystems, V. A. Deregibus, E. J. Jacobo, O. E. Ansin

IGC Proceedings (1977-2023)

Earth biomes are being deconstructed, through unprecedented rates of species disappearance or invasion (McCann 2000). This, added to the threat of global environmental change and changes in values of a developed society, caused that biodiversity became a topic that has captured the attention of the public as well as the scientific community. Such concern on the importance of biodiversity is based in four basic reasons clearly described by West (1993): (i) morality, that aims for the protection of species; (ii) aesthetics, as people desire to see and appreciate the living parts of nature; (iii) economics and, (iv) the array …

The Effect Of Phosphorus Fertilization On Botanical Composition And Production In Temperate Pastures In Argentina, E. J. Jacobo, A. M. Rodríguez, M. F. Garbulsky, P. Scardoni, V. A. Deregibus

IGC Proceedings (1977-2023)

The objective of this paper is to evaluate floristic changes and above-ground primary production in native grasslands and old pastures dominated by tall fescue (Festuca arundinacea) that were fertilized with different levels of phosphorus. For this, aerial biomass was sequentially harvested from November 1998 to October 1999. Above-ground production of native grassland more than doubled (from 3000 to 7300 kg DM/ha) with the highest level of P through the increment of three naturalized species: the winter annual ryegrass (Lolium multiflorum) and two legumes: white clover (Trifolium repens) and lotus (Lotus corniculatus). In …

Determining Pasture Biodiversity With Nirs, K. J. Moore, D. J. Barker

IGC Proceedings (1977-2023)

Research was conducted to assess the potential of using near infrared reflectance spectroscopy (NIRS) to determine botanical composition and measures of species diversity in pasture samples. Samples were collected from six hill country (Ballantrae) and two lowland (Aorangi) pastures in New Zealand. Samples were collected in summer (March) and Autumn (May) and subsamples were dissected to determine botanical composition and species diversity. Measures of diversity included species richness, Shannon’s index, and Simpson’s index. Reflectance data were collected from a second subsample that had been dried and finely ground. Calibrations were developed using modified partial least squares. Acceptable calibration equations were …

Vegetation Changes In Southeast Australian Temperate Grasslands, D. L. Garden, T. P. Bolger

IGC Proceedings (1977-2023)

In temperate areas of southeast Australia, the combined effects of tree clearing, grazing, application of fertilizer and the introduction of exotic species have modified the original grasslands. This paper describes these changes and attempts to explain them in terms of ecological principles derived from North American grasslands. Stability of the original grasslands appears to have been due to the lack of disturbance and the slow rates of nitrogen (N) cycling within them. Increased N cycling after disturbance has allowed invasion of species better adapted to higher N status, particularly exotic annual grasses and weeds. The present composition of grasslands, in …

The Effects Of Grazing Management And Fertilization On Grassland Diversity And Productivity, Warren Mcg. King, David R. Kemp

IGC Proceedings (1977-2023)

The effects of management practices on plant species diversity and productivity within a naturalised grassland was studied as part of a large-scale experiment designed to investigate issues of sustainability in temperate Australia. Fertiliser increased the production but reduced the diversity of the sward. The main decline was in exotic weed species. Strategic grazing resulted in a small increase in pasture diversity but a reduction in productivity. There was a consistent decline in diversity as productivity increased, across all treatments.

Pasture Dynamics After Sodseeding Cool Season Species With Or Without Glyphosate In Subtropical Natural Grasslands, Luciana M. Rizo, E. L. Moojen, Fernando L. F. De Quadros, F. E. Schlick, F. L. Correa

IGC Proceedings (1977-2023)

This trial was conducted to evaluate vegetation dynamics of natural grasslands fertilized and sodseeded with the cool season species Italian ryegrass (Lolium multiflorum), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus) with or without glyphosate. Treatments that included herbicide spraying on natural vegetation caused a substitution of perennial grasses by undesirable species, and did not show a significant contribution of introduced species. Andropogon lateralis, Paspalum notatum, Paspalum dilatatum and Paspalum plicatulum almost disappeared, and were replaced by Chaptalia nutans and Apium spp, among others.