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Articoli di riviste sul tema "Temperate pastures"
1
Kemp, D. R., e P. M. Dowling. "Towards sustainable temperate perennial pastures". Australian Journal of Experimental Agriculture 40, n. 2 (2000): 125. http://dx.doi.org/10.1071/ea98003.
Testo completoAbstract (sommario):
Naturalised pastures across the higher rainfall (>600 mm) perennial pasture zone of south-eastern Australia are less productive than they were, while sown pastures fail to maintain their initial levels of production. Several factors have contributed to this, including lack of knowledge of suitable grazing practices, weed invasion, increasing acid soils, rising water tables and poor management practices during droughts. A key issue in each case is the decline in perennial grass species which is both a cause and effect of the decline in productivity and sustainability of these ecosystems. This paper introduces a volume devoted to the largest collaborative study done to evaluate tactics for better grazing management and to improve the sustainability of perennial pasture ecosystems. Grazing practices to manage the composition of pastures have been largely neglected in pasture research, but are an important first step in improving pasture sustainability. This paper also outlines a new, open communal grazing experimental design which was developed and used across 24 sites on farms in New South Wales, Victoria, Tasmania and South Australia, to evaluate tactics for grazing management. The general aim across these experiments was to maintain (if adequate) or enhance (if degraded), the proportion of desirable perennial grasses in the sward to achieve more sustainable pastures. The results will provide the basis for building more sustainable grazing systems.
2
Pearson, C. J., R. Brown, W. J. Collins, K. A. Archer, M. S. Wood, C. Petersen e B. Bootle. "An Australian temperate pastures database". Australian Journal of Agricultural Research 48, n. 4 (1997): 453. http://dx.doi.org/10.1071/a96095.
Testo completoAbstract (sommario):
A census of pasture types and their composition and attributes (e.g. purpose and carrying capacity) was carried out throughout southern Australia from June to October 1994. This paper describes the survey process and subsequent creation of an Australian temperate pastures database. Data were created for 562 local government areas (LGAs) from ‘desk estimates’ by trained agriculturists. They identified about 2500 pasture types, which were grouped into 120 standardised pasture categories. Some findings from the data are identified, namely the high relative importance on an area basis of unimproved native pastures, the importance of weedy species (e.g. Vulpia), and the marked decline with increasing rainfall in importance of annual medics compared with subterranean clover. This paper provides examples of the data and their use for assessment of the regional economic impact of increases in productivity of pasture species.
3
Eyles, Alieta, Garth Coghlan, Marcus Hardie, Mark Hovenden e Kerry Bridle. "Soil carbon sequestration in cool-temperate dryland pastures: mechanisms and management options". Soil Research 53, n. 4 (2015): 349. http://dx.doi.org/10.1071/sr14062.
Testo completoAbstract (sommario):
Permanent pastures, which include sown, native and naturalised pastures, account for 4.3 Mha (56%) of the national land use in Australia. Given their extent, pastures are of great interest with respect to their potential to influence national carbon (C) budgets and CO2 mitigation. Increasing soil organic C (SOC) mitigates greenhouse gases while providing other benefits such as pasture productivity, soil health and ecosystem services. Several management approaches have been recommended to increase C sequestration in pasture-based systems; however, results have proved variable and often contradictory between sites and years. Here, we present an overview of the processes and mechanisms responsible for C sequestration in permanent pastures. In addition, we discuss the merits of traditional and emerging pasture-management practices for increasing SOC in pastures, with a focus on dryland pasture systems of south-eastern Australia. We conclude by summarising the knowledge gaps and research priorities for soil C-sequestration research in dryland pastures. Our review confirms that soils under a range of pasture types have considerable potential for sequestration of atmospheric CO2 in Australia, and that the magnitude of this potential can be greatly modified by pasture-management practices. Although the shortage of long-term studies under Australian conditions limits our ability to predict the potential of various management approaches to sequester soil C, our review indicates that prevention of erosion through maintenance of groundcover and adoption of options that promote deep C sequestration are likely to confer broad-scale maintenance or increases in SOC in pasture soils over a decade or longer. We acknowledge that the evidence is limited; therefore, confidence in the recommended practices in different locations and climates is largely unknown.
4
Lattimore, MAE. "Pastures in temperate rice rotations of south-eastern Australia". Australian Journal of Experimental Agriculture 34, n. 7 (1994): 959. http://dx.doi.org/10.1071/ea9940959.
Testo completoAbstract (sommario):
Legume-based pastures have long been an integral part of rice growing in the southern New South Wales irrigation areas and still offer potential to improve the productivity, profitability, and sustainability of the temperate rice-cropping system.This paper reviews both historical and current aspects of pastures in temperate rice rotations in southern New South Wales and highlights the importance of pastures in sustaining this cropping system as environmental pressures increase. Topics discussed include pasture species and rotations, their role in improving soil fertility and sustainability, the value of pastures in weed control, and their management for maximum profitability.
5
Vere, D. T., R. E. Jones e M. H. Campbell. "Long-term change in the economic productivity of four major pasture categories on the south-eastern Tablelands of New South Wales". Rangeland Journal 23, n. 2 (2001): 148. http://dx.doi.org/10.1071/rj01002.
Testo completoAbstract (sommario):
The perception of change or decline in the productivity of temperate pastures in south-eastern Australia is an important concern to livestock producers and pasture scientists. Much of this concern relates to reductions in the proportions of desirable species in the composition of pasture systems as a result of increased soil and weed problems. The purpose of this paper is to investigate trends in the long-term economic productivity of four categories of temperate pastures (all introduced pastures, introduced perennial grasses, introduced legumes and all native pastures) on the central and southern tablelands of New South Wales. The results provide evidence of economic productivity decline in the all introduced pastures category in relation to sheep production, but this has been due to productivity decline in the dominant legume component of the introduced pastures. In contrast, there has been strong growth in the economic productivity of the introduced perennial grass pastures. Abnormally high beef cattle numbers in the mid-1970s appear to have created an illusion of high productivity and subsequent decline in all introduced pastures. In contrast, the economic productivity of the native pastures which are the bulk of the region's grazing areas, has fallen substantially.
6
Vere, D. T., R. E. Jones e M. H. Campbell. "The economics of temperate pasture systems on the central and southern Tablelands of New South Wales". Rangeland Journal 23, n. 2 (2001): 159. http://dx.doi.org/10.1071/rj01003.
Testo completoAbstract (sommario):
Pastures are the basis of most forms of agricultural production on the New South Wales central and southern tablelands. Pastures occupy the bulk of the region's landmass and pasture-based livestock production annually contributes more than three-quarters of the regional gross value of rural production. Throughout the region, there is substantial variation in pasture composition, ranging from high quality introduced perennial grasses and legumes to pastures comprising mainly low quality native species. This paper examines the economics of the main categories of temperate pastures over a range of soil fertility-rainfall environments on the south-eastern tablelands areas of New South Wales. Using a linear programming model and discounted development budgets, the results demonstrate the strong influence of the environment on the economics of the individual pasture systems. The highest economic returns in both the short and longer-terms were to the introduced perennial grass pastures in most of the environments. Pastures based on introduced legumes and the high quality native species also generated sound economic returns, although there are recognised problems with the persistence of the legume pastures. Over time, the returns to the better quality native pastures compare favourably with the introduced legumes and are better suited to acidic soils than the perennial grasses. Low quality native species produced relatively poor economic returns in all environments and unfortunately, are the main pasture type in the region's less favourable environments.
7
Jones, Roger A. C. "Virus diseases of pasture grasses in Australia: incidences, losses, epidemiology, and management". Crop and Pasture Science 64, n. 3 (2013): 216. http://dx.doi.org/10.1071/cp13134.
Testo completoAbstract (sommario):
This paper reviews current knowledge for Australia over the occurrence, losses caused, epidemiology, and management of virus diseases of pasture grasses. It also reviews all records of viruses in wild grasses likely to act as alternative host reservoirs for virus spread to nearby pastures or crops. Currently, 21 viruses have been found infecting 36 pasture or forage grass species and 59 wild grass species. These viruses are transmitted by arthropod vectors (mites or insects) or, in one instance, via grass seeds. Their modes of transmission are critical factors determining their incidences within pastures in different climatic zones. Large-scale surveys of perennial grass pastures growing in regions with temperate–Mediterranean climates revealed that Barley yellow dwarf virus (BYDV), Cereal yellow dwarf virus (CYDV), and Ryegrass mosaic virus (RyMV) sometimes reach high infection incidences. The same was true for BYDV and CYDV when perennial pasture grasses and wild grasses growing outside pastures were surveyed to establish their occurrence. Smaller scale surveys of grasses growing both inside and outside annual pastures found that Wheat streak mosaic virus (WSMV) infection could also reach high incidences in some annual grass species. Herbage yield loss data are available demonstrating potentially serious impacts on pasture production under Australian conditions from BYDV infection in perennial ryegrass swards, and from RyMV infection in both perennial and Italian ryegrass swards. Also, infection with BYDV or RyMV diminished the ability of infected pasture grass plants to compete with pasture legumes or weeds. Host resistance to BYDV, CYDV, and/or RyMV has been identified within a few temperate–Mediterranean pasture grasses, and is available for use in Australian pasture breeding programs. Integrated Disease Management tactics involving phytosanitary, cultural, chemical, and host resistance measures were devised against BYDV, CYDV, and RyMV infection in mixed species pasture, but no field experiments were undertaken with pasture grasses to validate their inclusion. Several other grass viruses that occur in other countries, but have not been looked for in Australia, are potentially important, especially in temperate–Mediterranean pasture grass species. With few exceptions, research on viruses of perennial or annual tropical–subtropical pasture or wild grass species growing within or outside pastures has focussed only on virus identification and characterisation studies, and information on incidences in pastures, losses caused, epidemiology, and management is lacking. Critical research and development gaps that need addressing are identified.
8
McPhee, M. J., J. F. Ayres e M. L. Curll. "Growth periodicity of introduced pastures on the northern tablelands of New South Wales". Australian Journal of Agricultural Research 48, n. 6 (1997): 831. http://dx.doi.org/10.1071/a96176.
Testo completoAbstract (sommario):
This paper reports on the growth periodicity of introduced temperate perennial pastures in a summer-rainfall environment in the high-rainfall zone of eastern Australia. Data were derived from an experiment (1985-87) directed at evaluating pasture cultivars when sown in binary mixtures grazed by sheep. The data were also simulated by using the decision support system SheepO (Version 4·0) and validated by visual techniques, deviance measures, and statistical tests. The model simulated pasture growth rate and total biomass with acceptable accuracy. The study provided a quantification of the growth rhythm of temperate perennial pastures in this environment. The data show that growth rhythm comprises a high growth rate (>50 kg DM/ha·day) during the primary growth cycle in spring, a moderate growth rate (20-50 kg DM/ha·day) during the secondary growth cycle in summer-autumn, and low growth rate (<20 kg DM/ha·day) in winter. The growth performance of introduced pastures based on cv. Demeter tall fescue (Festuca arundinacea) exceeded that of pastures based on cv. Sirosa phalaris (Pharlaris aquatica) in all seasons, at low and high stocking rates, and in all 3 years. The results highlight the potential for pasture cultivars with enhanced seasonal growth rate to increase the pasture feed supply for grazing animals.
9
King, K. L., e K. J. Hutchinson. "Pasture and grazing land: assessment of sustainability using invertebrate bioindicators". Australian Journal of Experimental Agriculture 47, n. 4 (2007): 392. http://dx.doi.org/10.1071/ea05270.
Testo completoAbstract (sommario):
Impacts of practices frequently used to manage Australian pastures are reviewed with the aim of determining which groups are responsive to changes in grazing regime, fertiliser use, pasture types, tree clearing, pesticide use, liming and irrigation. Invertebrate groups sensitive to pasture management regimes may be potential candidates for use as bioindicators of ecological sustainability of these pasture types. This review concentrates on the more intensively utilised temperate pastures of southern Australia, as very little work has been done on the impact of the grazing animal and pasture management on invertebrate fauna on the extensive rangelands of the arid and semiarid zones. Background to the relative importance of invertebrates in the functioning of the pasture ecosystem is given. This has culminated in the construction of food webs for two temperate perennial pastures (an unfertilised, native and a fertilised, sown pasture) at Armidale, NSW, for which there is comprehensive data available. Invertebrate bioindicators of pasture sustainability emerged from the consideration of grazing lands and invertebrate responses. Currently, only four groups would seem to be likely candidates as bioindicators of sustainability of pastures. These are soil nematodes, earthworms, protozoa and Collembola. The main difficulty in monitoring these groups is that it requires specialist expertise, and services provided by commercial laboratories for routine biological soil tests are still in their infancy. There are gaps in our knowledge of how invertebrate fauna react to the pressing issues of soil acidity and salinity.
10
Fulkerson, WJ, e K. Slack. "Estimating mass of temperate and tropical pastures in the subtropics". Australian Journal of Experimental Agriculture 33, n. 7 (1993): 865. http://dx.doi.org/10.1071/ea9930865.
Testo completoAbstract (sommario):
The feasibility of estimating, with acceptable precision, temperate and tropical pasture mass in a subtropical environment was evaluated. For the tropical grasses kikuyu (Pennisetum clandestinum) and setaria (Setaria ancepts), 3 different pasture meters were calibrated against 1 of 3 dry matter (DM) estimates. Temperate pastures (predominantly Lolium perenne and Trifolium repens) were evaluated using the Ellinbank rising plate meter (RPMl) calibrated against DM to ground level. A single regression equation was developed for syegrass-white clover pasture from data pooled within season over first- and second-year swards. The s.e. of estimate (s.e.e.) for assessing tropical grass pasture mass using RPMl was similar to that for a heavier Ellinbank meter and substantially lower than that for the electronic pasture probe. Using RPMl, separate regression equations were required for early (November-February) and late (March-May) season determinations for both kikuyu and setaria. The regression equations were based on calibrations against shoot DM (>5 cm stubble height for kikuyu and 6 cm for setaria) and are only applicable to well-managed and highly utilised pastures. Calibrations of all pasture meters over all months to green DM (senescent leaf and stem removed) gave a lower s.e.e. than total DM (kikuyu 138 v. 177 kg DM/ha, n = 171; setaria 211 v. 224 kg DM/ha, n = 177) whilst shoot DM gave a more substantial reduction in s.e.e. (kikuyu 95 v. 147 kg DM/ha; setaria 140 v. 193 kg DM/ha).
Tesi sul tema "Temperate pastures"
1
Thulin, Susanne Maria, e smthulin@telia com. "Hyperspectral Remote Sensing of Temperate Pasture Quality". RMIT University. Mathematical and Geospatial Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090507.163006.
Testo completoAbstract (sommario):
This thesis describes the research undertaken for the degree of Doctor of Philosophy, testing the hypothesis that spectrometer data can be used to establish usable relationships for prediction of pasture quality attributes. The research data consisted of reflectance measurements of various temperate pasture types recorded at four different times (years 2000 to 2002), recorded by three hyperspectral sensors, the in situ ASD, the airborne HyMap and the satellite-borne Hyperion. Corresponding ground-based pasture samples were analysed for content of chlorophyll, water, crude protein, digestibility, lignin and cellulose at three study sites in rural Victoria, Australia. This context was used to evaluate effects of sensor differences, data processing and enhancement, analytical methods and sample variability on the predictive capacity of derived prediction models. Although hyperspectral data analysis is being applied in many areas very few studies on temperate pastures have been conducted and hardly any encompass the variability and heterogeneity of these southern Australian examples. The research into the relationship between the spectrometer data and pasture quality attribute assays was designed using knowledge gained from assessment of other hyperspectral remote sensing and near-infrared spectroscopy research, including bio-chemical and physical properties of pastures, as well as practical issues of the grazing industries and carbon cycling/modelling. Processing and enhancement of the spectral data followed methods used by other hyperspectral researchers with modifications deemed essential to produce better relationships with pasture assay data. As many different methods are in use for the analysis of hyperspectral data several alternative approaches were investigated and evaluated to determine reliability, robustness and suitability for retrieval of temperate pasture quality attributes. The analyses employed included stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR). The research showed that the spectral research data had a higher potential to be used for prediction of crude protein and digestibility than for the plant fibres lignin and cellulose. Spectral transformation such as continuum removal and derivatives enhanced the results. By using a modified approach based on sample subsets identified by a matrix of subjective bio-physical and ancillary data parameters, the performance of the models were enhanced. Prediction models from PLSR developed on ASD in situ spectral data, HyMap airborne imagery and Hyperion and corresponding pasture assays showed potential for predicting the two important pasture quality attributes crude protein and digestibility in hyperspectral imagery at a few quantised levels corresponding to levels currently used in commercial feed testing. It was concluded that imaging spectrometry has potential to offer synoptic, simultaneous and spatially continuous information valuable to feed based enterprises in temperate Victoria. The thesis provide a significant contribution to the field of hyperspectral remote sensing and good guidance for future hyperspectral researchers embarking on similar tasks. As the research is based on temperate pastures in Victoria, Australia, which are dominated by northern hemisphere species, the findings should be applicable to analysis of temperate pastures elsewhere, for example in Western Australia, New Zealand, South Africa, North America, Europe and northern Asia (China).
2
Johnston, William Henry, University of Western Sydney, of Science Technology and Environment College e School of Environment and Agriculture. "The role of Eragrostis curvula (Schrad.) Nees. complex in temperate pastures in southeastern Australia". THESIS_CSTE_EAG_Johnston_W.xml, 2003. http://handle.uws.edu.au:8081/1959.7/29.
Testo completoAbstract (sommario):
This thesis examines the hypothesis that, in southern New South Wales and northeast Victoria, Australia, palatable taxa of E. curvula offer advantages that complement those of the species that are traditionally sown in temperate pastures in a landscape context.This hypothesis was based on a review of literature showing that, prior to European settlement, the vegetation, the landscape and the climate were broadly in balance, and the wateruse pattern of the vegetation of southeastern Australia resulted in water being used more-or-less completely by the end of summer. This maximised the capacity of the soil to take up and store water during autumn and winter.Three grazing experiments and one spaced-plant species evaluation study were used to assess the role of summer-growing, C4 Eragrostis curvula in pastures in the temperate zone of southeastern Australia.Issues relating to pasture production and the productivity of wool-growing sheep were investigated. Factors affecting the sustainability of the pastures and their potential on and off site impacts were emphasised.Modelling was used to explore issues of water use, arising from the grazing experiments. It is concluded that the persistence, production, water use patterns, and the adaptability of palatable varieties of E. curvula make it a useful and complementary addition to the range of species that are currently available for use as sown pastures in southern Australia.Doctor of Philosophy (PhD)
3
Johnston, William Henry. "The role of Eragrostis curvula (Schrad.) Nees. complex in temperate pastures in southeastern Australia /". View thesis View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030506.100204/index.html.
Testo completo
4
Wallace, Richard Paul, e n/a. "Effects of trees on temperate native pasture productivity". University of Canberra. Applied Science, 1999. http://erl.canberra.edu.au./public/adt-AUC20061113.160245.
Testo completoAbstract (sommario):
The goal of this work was to quantify the effects of eucalypt woodland blocks on the
productivity of native pastures. This research was conducted on the Southern Tablelands
of New South Wales. Tree planting or retention is seen by many as an important tool in
addressing the problems of soil degradation resulting from clearing and pasture
improvement that threaten the sustainability of pasture systems. In particular these are
dry land salinity and erosion, both of which affect large areas of agricultural lands in the
south east of Australia. Whilst native tree cover remains over substantial portions of
Australian pasture lands, mainly on steeper slopes and poorer soils, little has been done
to measure the effects of trees on pasture productivity and soil fertility on the Southern
Tablelands. Previous studies in other areas have shown a range of effects�from
facilitation to inhibition�of pasture growth in the presence of trees. Soil fertility
beneath trees has been shown by a number of workers to be elevated in comparison with
situations in the open. Given that the range of effects may be highly site dependent,
application of results from one area to another may not be valid. Thus it is necessary to
measure tree effects on a regional scale if results are to be reliable.
Pasture productivity was assessed over a two year period on four sites in the vicinity of
Bungendore, New South Wales. A pair of plots was selected on each site, one plot in a
block of eucalypt woodland, and the other nearby in an exposed, open situation. Plots
were chosen to be as similar to each other as possible with the exception of tree cover.
Treed plots had a tree basal area of between 10 and 20 m2 ha-1 and plots had an area of
900 m2. Two of the sites were on granitic soils and had a tree cover consisting
predominantly of Eucalyptus pauciflora. The remaining two sites were on soil derived
from sedimentary rocks with tree cover consisting mainly of E. mannifera, E. dives and
E. melliodora. Perennial native pasture species present were similar across all sites,
although their relative contributions to standing biomass varied between sites. As the
plots were grazed during the period of measurement, productivity and offtake were
measured seasonally using exclosure cages on each plot. Pasture standing biomass was
assessed using the comparative yield technique.
Microclimate was monitored in each plot by automatic weather stations. Soil moisture
to a depth of 45 cm was measured by time domain reflectometry using permanent
probes in each plot. Ten additional survey plots on each site, covering the range of tree
basal area from 0 - 30 m2 ha-1, were assessed each season in the second year for standing
biomass, soil fertility and pasture quality; expressed by nitrogen content and dry matter
digestibility. Pasture floristics were measured using the dry-weight-rank method. These
additional plots were chosen to be as representative of the paddocks as possible.
Over the two years that productivity was measured, it was found to be higher under
trees than in the open. This was predominantly due to higher winter and spring growth
within treed plots. Grazing offtake was also found to be higher under trees, partly
accounting for lower standing biomass found in the treed plots.
Wind run, evapotranspiration and photosynthetically active radiation were all reduced
by the presence of trees. Beneficial effects of shelter from winds may largely explain
the higher productivity observed in the treed plots, and could outweigh negative effects
of below ground competition and radiation interception by tree canopies at low to
moderate tree densities. Soil moisture was not affected by the presence of trees. Soil
fertility also did not differ between treed and open plots nor was there any difference in
pasture nitrogen content or dry matter digestibility.
On the sites where soils were derived from sedimentary rocks, pasture floristics were
found to be related to tree basal area. Themeda ausfralis biomass was negatively related
to tree basal area, and was partially replaced by large tussock species such as Poa
sieberiana and Chionochloa pallida. A reduction of pasture quality resulted, particularly
as the latter species is not grazed to any significant extent.
Given the desirability of having deep rooted perennial components in grazing lands, the
results of this study indicate that it may be possible to utilise trees to assist in preventing
or reducing a range of adverse environmental consequences arising from agricultural
activities, without unduly compromising pasture productivity. Additionally, the wide
range of environmental conditions provided by a mix of treed and open pasture
promotes a higher degree of heterogeneity of the herbaceous layer. This may assist in
maintaining productivity over a greater range of climatic conditions than would be the
case with a more homogeneous pasture.
5
Slaughter, Lindsey C. "SOIL MICROBIAL COMMUNITY RESPONSE TO CLIMATE CHANGE: RESULTS FROM A TEMPERATE KENTUCKY PASTURE". UKnowledge, 2012. http://uknowledge.uky.edu/pss_etds/8.
Testo completoAbstract (sommario):
Climate change is likely to alter plant species composition and interactions between plants and soil microbes that together dictate the quantity and quality of forage produced in pastures, the base of animal production in central Kentucky. This study assessed the seasonal dynamics of soil microbes and their response to increased temperature (+3oC) and growing season precipitation (+30% of the mean annual). Total soil microbial biomass, community composition, enzyme activities, potential carbon mineralization, and catabolic responses to selected substrates were measured seasonally in the different climate treatments. In this system, seasonal variability was a dominant driving factor for all the soil microbial characteristics that I investigated. Summer maxima and winter minima were identified in the active microbial biomass, while soil microbial community structure differed between each season. Extracellular enzyme activities were generally highest in either the spring or summer, while seasonal patterns for each substrate were unique across catabolic response profiles. Climate treatments produced few significant main or interactive effects on the soil microbial biomass and function. This resiliency, coupled with evidence of functional redundancy, suggests that central Kentucky pasture ecosystems may be well-equipped to handle future environmental stress associated with climate change and to maintain critical ecosystem services.
6
Fletcher, Donald Bryden, e N/A. "Population Dynamics of Eastern Grey Kangaroos in Temperate Grasslands". University of Canberra. Resource, Environmental & Heritage Sciences, 2006. http://erl.canberra.edu.au./public/adt-AUC20070808.152438.
Testo completoAbstract (sommario):
This thesis is about the dynamics of eastern grey kangaroo (Macropus giganteus) populations
and their food supplies in temperate grasslands of south-eastern Australia. It is based on the
study of three populations of eastern grey kangaroos inhabiting �warm dry�, �cold dry�, and
�warm wet� sites within the Southern Tablelands climatic region. After a pilot survey and
methods trial in early 2001, the main period of study was from August 2001 to July 2003.
The study populations were found to have the highest densities of any kangaroo populations,
450 to 510 km-2. Their density was the same at the end of the two year study period as at the
beginning, in spite of a strong decline in herbage availability due to drought. The eastern grey
kangaroo populations were limited according to the predation-sensitive food hypothesis.
Fecundity, as the observed proportion of females with late pouch young in spring, was high,
in spite of the high kangaroo density and restricted food availability. Age-specific fecundity
of a kangaroo sample shot on one of the sites in 1997 to avert starvation was the highest
reported for kangaroos. Thus, limitation acted through mortality rather than fecundity.
Population growth rate was most sensitive to adult survival but the demographic rate that had
the greatest effect in practice was mortality of juveniles, most likely sub-adults. The
combination of high fecundity with high mortality of immatures would provide resilience to
low levels of imposed mortality and to fertility control.
The normal pattern of spring pasture growth was not observed in the drought conditions and
few of the recorded increments of growth were of the magnitude considered typical for sites
on the southern and central tablelands. Temperature was necessary to predict pasture growth,
as well as rainfall, over the previous two months. The best model of pasture growth (lowest
AICc) included negative terms for herbage mass, rainfall over the previous two months, and
temperature, and a positive term for the interaction between rainfall and temperature. It
accounted for 13% more of the variation in the data than did the simpler model of the type
used by Robertson (1987a), Caughley (1987) and Choquenot et al. (1998). However this was
only 63% of total variation. Re-evaluation of the model based on measurements of pasture
growth in more typical (non-drought) conditions is recommended. Grazing had a powerful
influence on the biomass of pasture due to the high density of kangaroos. This is a marked
difference to many other studies of the type which have been conducted in semi-arid
environments where rainfall dominates.
The offtake of pasture by kangaroos, as estimated on the research sites by the cage method,
was linear on herbage mass. It was of greater magnitude than the more exact estimate of the
(curved) functional response from grazedowns in high�quality and low�quality pastures.
The widespread recognition of three forms of functional response is inadequate. Both the
theoretical basis, and supporting data, have been published for domed, inaccessible residue,
and power forms as well (Holling 1966; Noy-Meir 1975; Hassell et al. 1976, 1977; Short
1986; Sabelis 1992). Eastern grey kangaroos had approximately the same Type 2 functional
response when consuming either a high quality artificial pasture (Phalaris aquatica), or dry
native pasture (Themeda australis) in autumn. Their functional response rose more gradually
than those published for red kangaroos and western grey kangaroos in the semi-arid
rangelands, and did not satiate at the levels of pasture available. This gradual behaviour of
the functional response contributes to continuous stability of the consumer-resource system,
as opposed to discontinuous stability.
The numerical response was estimated using the ratio equation, assuming an intrinsic rate of
increase for eastern grey kangaroos in temperate grasslands of 0.55. There is indirect
evidence of effects of predation in the dynamics of the kangaroo populations. This is
demonstrated by the positive relationship between r and kangaroo density. Such a
relationship can be generated by predation. A desirable future task is to compile estimates of
population growth rate and simultaneous estimates of pasture, in the absence of predation,
where kangaroo population density is changing, so that the numerical response can be
estimated empirically.
The management implications arising from this study are numerous and a full account would
require a separate report. As one example, kangaroos in these temperate grasslands are on
average smaller, eat less, are more numerous, and are more fecund, than would be predicted
from other studies (e.g. Caughley et al. 1987). Thus the benefit of shooting each kangaroo, in
terms of grass production, is less, or, in other words, more kangaroos have to be shot to
achieve a certain level of impact reduction, and the population will recover more quickly, than
would have been predicted prior to this study.
Secondly, of much importance to managers, the interactive model which can readily be
assembled from the products of Chapters 4, 5 and 8, can be used to test a range of
management options, and the effect of variation in weather conditions, such as increased or
decreased rainfall. For example, the model indicates that commercial harvesting (currently
under trial in the region), at the maximum level allowed, results in a sustainable harvest of
kangaroos, but does not increase the herbage mass, and only slightly reduces the frequency of
crashes when herbage mass falls to low levels. (To demonstrate this with an ecological
experiment would require an extremely large investment of research effort.) However, an
alternative �national park damage mitigation� formula, which holds kangaroo density to about
1 ha-1, is predicted to increase herbage mass considerably and to reduce the frequency of
crashes in herbage mass, but these effects would be achieved at the cost of having to shoot
large numbers of kangaroos. Thus, aside from many specific details of kangaroo ecology, the
knowledge gained in this study appears to have useful potential to illustrate to managers the
dynamic properties of a resource-consumer system, the probabilistic nature of management
outcomes, and the consequences of particular kangaroo management proposals.
7
Lima, Luís Otávio da Costa de. "Lisina e metionina na dieta de vacas de alta produção mantidas em pastagens de azevém (Lolium multiflorum Lam.) e suplementadas com concentrado de baixo teor proteico". Universidade Federal de Santa Maria, 2017. http://repositorio.ufsm.br/handle/1/11676.
Testo completoAbstract (sommario):
Current research looked into the effects of supplementing essential amino acids L-lysine and DL-methionine to lactating dairy cows, grazing annual ryegrass and receiving a low protein concentrate meal. Twenty Holstein cows were managed in a 2x2 crossover experimental design, with two treatments and two periods. Cows received the same diet in both treatments, except for the inclusion of 20g lysine and 60g methionine in one treatment. This aimed at supplying 6.92% and 2.34% of the metabolizable protein in lysine and methionine, respectively, as suggested by the Cornell Net Carbohydrate and Protein System (CNCPS). No significant differences were found in milk (36,19 vs. 35,97kg), total crude protein (1,14 vs. 1,15kg) and lactose (1,62 vs. 1,66kg) yields, casein content (2,55 vs. 2,55%), somatic cell count (309 vs. 363cél.mL-1), milk urea nitrogen (12,40 vs. 12,15mg.dL-1), and blood urea (25,01 vs. 25,09mg.dL-1) for the control and the amino acid supplemented treatments, respectively. The amino acid supplemented treatment presented a lower milk fat content (3,58 vs. 3,39%), but no differences yield (1,29 vs. 1,21kg), which led to the same 4% milk fat corrected milk yield (33,8 vs. 32,6kg). The lower milk fat content resulted in a lower total milk solids content (12,56 vs. 12,26%) in the amino acid supplemented treatment, in spite of this treatment presenting similar crude protein (3,17 vs. 3,20%) and lactose (4,48 vs. 4,61%) contents. Animals receiving the amino acid supplementation also presented lower creatinine blood (0,74 vs. 0,89mg.dL-1) suggesting a lower muscle tissue mobilization, in spite of their similar urine urea nitrogen test (264,15 vs. 351,30 mg.dL-1) and urine creatinine (42,46 vs. 38,04mg.dL-1). Rumen-protected lysine and methionine supplementation did not affect milk yield but did affect milk composition and reduced serum creatinine.Neste trabalho, avaliou-se os efeitos da adição dos aminoácidos essenciais L-lisina e DL-metionina na dieta de vacas em lactação, mantidas em pastagens de azevém anual e suplementadas com concentrado de baixo teor proteico. Foram utilizadas 20 vacas da raça holandesa em um delineamento experimental crossover (2x2), submetidas a dois tratamentos e dois períodos. Ambos tratamentos receberam dietas iguais, com exceção da inclusão ou não de 20 e 60g dos aminoácidos lisina e metionina, respectivamente, buscando atingir os níveis de 6,92% de lisina e 2,34% de metionina na proteína metabolizável, sugeridos pelo Cornell Net Carbohydrate and Protein System (CNCPS). Não foram encontradas diferenças significativas para produção de leite (36,19 vs. 35,97kg), produção total de proteína bruta (1,14 vs. 1,15kg) e de lactose (1,62 vs. 1,66kg), teor de caseína (2,55 vs. 2,55%), contagem de células somáticas (309 vs. 363cél.mL-1), nitrogênio ureico no leite (12,40 vs. 12,15mg.dL-1) e ureia no sangue (25,01 vs. 25,09mg.dL-1) para os grupos controle e com adição de lisina e metionina, respectivamente. O grupo que recebeu a suplementação apresentou menor teor de gordura no leite (3,58 vs. 3,39%), mas igual volume de gordura produzido (1,29 vs. 1,21kg), não interferindo na produção de leite quando esta variável foi corrigida para 4% de gordura (33,8 vs. 32,6kg). O teor menor de gordura fez com que o teor de sólidos totais fosse menor no grupo que recebeu os aminoácidos (12,56 vs. 12,26%), embora este tenha apresentado teor igual de proteína (3,17 vs. 3,20%) e superior de lactose (4,48 vs. 4,61%). Os animais que receberam os aminoácidos também apresentaram teores inferiores de creatinina no sangue (0,74 vs. 0,89mg.dL-1) sugerindo uma mobilização menor de tecidos musculares, embora tenham apresentado níveis semelhantes de ureia na urina (264,15 vs. 351,30 mg.dL-1) e creatinina na urina (42,46 vs. 38,04mg.dL-1). O fornecimento dos aminoácidos lisina e metionina protegidos na degradação ruminal, não influenciou a produção total de leite, mas sim sua composição, além de reduzir os níveis de creatinina sérica.
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Mills, Annamaria. "Understanding constraints to cocksfoot (Dactylis glomerata L.) based pasture production". Phd thesis, Lincoln University. Agriculture and Life Sciences Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20070717.161658/.
Testo completoAbstract (sommario):
This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05.
The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N.
The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and N pastures, relative to fully irrigated control pastures.
Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures.
The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures.
Differences between the yields of +N and N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI).
In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.
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Khan, Shabana. "Factors affecting nitric oxide and nitrous oxide emissions from grazed pasture urine patches under New Zealand conditions". Lincoln University, 2009. http://hdl.handle.net/10182/1570.
Testo completoAbstract (sommario):
New Zealand is dominated by its agricultural industry with one of the most intensive farming practices being that of intensive dairying. New Zealand currently has approximately 5.3 million dairy cows that excrete up to 2.2 L of urine, per urination event, up to 12 times per day. This equates to 5.1 x10¹⁰ L per year or enough urine to fill over 1.2 million milk tankers. This sheer volume of urine and its associated N content has implications for the cycling of N within the pasture soils utilised, and New Zealand’s greenhouse gas budget due to the emission of N₂O from urine affected areas. The emission of nitric oxide (NO) from agricultural systems is also receiving increasing attention due to concerns about alterations in the balance of atmospheric trace gases and sinks. Worldwide there is a dearth of information with respect to the emissions of NO from urine-N deposition onto soils with only two in situ studies and no studies on the effects of soil pH, environmental variables or urine-N rate on NO fluxes. This present study has provided some fundamental information on the factors and processes affecting the emission of NO from bovine urine applied to pasture soils. Five experiments were performed in total; three laboratory experiments and two field experiments. The first laboratory experiment (chapter 4) examined the effect of the initial soil pH on NOx emissions from urine-N applied at 500 kg N ha⁻¹. Soil was treated to alter the initial soil pH over the range of 4.4 to 7.6. Initial soil pH affected rates of nitrification which in turn affected the decline in soil pH. Emissions of NO increased with increasing soil pH. However, a strong positive linear relationship was established between the NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity. The NO-N fluxes were higher under the more acidic soil conditions where N turnover was lower. The fluxes of N₂O did not follow the same pattern and were attributed to biological mechanisms. In experiment two (chapter 5) the objectives were to concurrently examine the effects of varying the soil temperature and the water-filled pore space (WFPS) on NOx emissions from urine-N. In this experiment increasing the soil temperature enhanced both the rate of nitrification and the rate of decrease in soil pH. The relationship between the net NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity was again demonstrated at the warmest soil temperature (22°C) where soil acidification had progressed sufficiently to enable abiotic NO formation. The NO-N fluxes increased with decreasing soil moisture and increasing soil acidity indicating abiotic factors were responsible for NO production. The Q10 response of the NO flux between 5 to 15°C decreased from 4.3 to 1.5 as WFPS increased from 11% to 87% respectively. Fluxes of N₂O increased with increasing WFPS and temperature indicating that denitrification was the dominant process. Results from experiments 2 and 3 indicated that the rate of nitrification had a direct bearing on the ensuing soil acidity and that it was this in conjunction with the available inorganic-N pools that affected NOx production. Therefore the third experiment examined the effect of urine-N rate on NOx emissions, with urine-N rate varied over 5 levels from 0 to 1000 kg N ha⁻¹, the highest rate being that found under maximal urine-N inputs to pasture. Rates of nitrification were diminished at the highest rates of urine-N applied and decreases in soil acidity were not as rapid due to this. Again significant but separate linear relationships were developed, for each urine-N rate used, between the NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity. The slope of these relationships increased with increasing urine-N rate. The NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, versus soil acidity was higher under 1000 kg N ha⁻¹, despite the lower soil acidity in this treatment. This indicated that the enhanced inorganic-N pool was also playing a role in increasing the NO flux. The N₂O fluxes were of limited duration in this experiment possibly due to conditions being disadvantageous for denitrification. In the field experiments two urine-N rates were examined under both summer and winter conditions at two urine-N rates. The emission factors after 71 days for NO-N in the summer were 0.15 and 0.20% of the urine-N applied for the 500 and 1000 kg N ha⁻¹ rates respectively while the respective N₂O-N fluxes were 0.14 and 0.16%. Under winter conditions the emission factors after 42 days for NO-N were <0.001% of the urine-N applied regardless of urine-N rate while the N₂O-N fluxes were 0.05 and 0.09% for the 500 and 1000 kg N ha⁻¹ urine-N rates respectively. The relationships and predictors of NO-N flux determined in the laboratory studies did not serve as strong indicators of the NO-N flux under summer conditions. Low emissions from urine-N over winter were due to the low soil temperatures and high WFPS. These studies have demonstrated that soil chemical and environmental variables influence the production of NOx and N₂O emissions from urine-N applied to soil and that seasonal effects have a significant impact on the relative amounts of NO-N and N₂O-N emitted from urine patches. Suggestions for future work are also made.
10
Kabine, Ezekiel Simon. "Evaluation of different temperature winter fodder species (Festulolium hybrids, dactylis species, lolium hybrids) and grass-legume mixtures in the warmer summer rainfall areas of South Africa". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1808.
Testo completoAbstract (sommario):
Thesis (MSc. (Pasture Science)) -- University of Limpopo, 2016South Africa is regarded as a semi-arid area; only 28% of the country receives more than 600 mm rainfall recorded annually. Sustainable utilization of cool season fodder grasses in summer rainfall areas to produce winter animal feed remains a major problem. Farmers are affected by a shortage of adequate, good quality herbage for livestock during winter and dry periods on commercial farms. The study aimed to evaluate and compare the production potential of six Festulolium hybrids, three Dactylis species, and five Lolium hybrids and three grass-legume mixtures in the summer rainfall area. A total of 17 cultivars were evaluated for their DM production under the treatment of different fertilizer levels on three planting dates (16 March 2011, 21 April 2011 and 4 April 2012). The study was carried out at Hygrotech Seed Company (Experimental site), Dewagensdrift in Moloto Village outside Pretoria in the Gauteng Province. Data was collected on a monthly basis from sub-plots of 1 m x 1 m (m2) in 51 plots of 1.5 m x 6 m (9 m2), with nine rows that were 10 cm apart arranged under RCBD with three replicates per cultivar. Harvested fresh samples were taken, weighed, dried at 60ºC until they reached a constant dry weight and weighed to determine DM content. A Fischer’s protected LSD at the 5 % level was performed to compare the treatment means. Over a period of three years of study, it shows that the low fertilizer level resulted in the lowest DM production, with no significant difference occurring between medium and high fertilizer levels. To achieve optimum DM production with minimum cost medium fertilizer is recommended. The cultivars responded differently to the three different planting dates. The time of planting had an effect on DM production in winter. It is recommended that Festulolium hybrids and Lolium hybrids be planted earlier (March) for better DM production in winter.
National Research Foundation (NRF)
Libri sul tema "Temperate pastures"
1
Peeters, Alain. Temperate grasses: Description, ecology and agronomic properties. Oxford: Blackwell Science, 2003.
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2
J, Rook A., Penning P. D e British Grassland Society, a cura di. Grazing management: The principles and practice of grazing, for profit and environmental gain, within temperate grassland systems ; poceedings of the British Grassland Society conference held at the Cairn Hotel, Harrogate, 29 February-2 March 2000. [Reading?]: British Grassland Society, 2000.
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3
International Workshop on Genetic Resources of Cool-season Pasture, Forage, and Food Legumes for Semi-arid Temperate Environments (1987 Aleppo, Syria). Legume genetic resources for semi-arid temperate environments: Proceedings of an International Workshop on Genetic Resources of Cool-season Pasture, Forage, and Food Legumes for Semi-Arid Temperate Environments, Cairo, Egypt, 19-2r June 1987. A cura di Smith Alan, Robertson Larry, United Nations Development Programme e International Center for Agricultural Research in the Dry Areas. Aleppo, Syria: International Center for Agricultural Research in Dry Areas, 1991.
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4
International Workshop on Genetic Resources of Cool-season Pasture, Forage, and Food Legumes for Semi-arid Temperate Environments (1987 Cairo, Egypt). Legume genetic resources for semi-arid temperate environments: Proceedings of an International Workshop on Genetic Resources of Cool-season Pasture, Forage, and Food Legumes for Semi-arid Temperate Environments, Cairo, Egypt, 19-24 June 1987. A cura di Smith Alan, Robertson L. D, United Nations Development Programme e International Center for Agricultural Research in the Dry Areas. Aleppo, Syria: ICARDA, 1991.
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5
(Contributor), Cecile Vanbellinghen, e John Frame (Contributor), a cura di. Wild And Sown Grasses: Profiles of a Temperate Species : Ecology, Biodiversity and Use. Food & Agriculture Organization of the UN (FA, 2004.
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6
David, Chapman, Rosemary Collins, Athole Marshall, Olivier Huguenin-Elie e Agustin Del Prado. Improving Grassland and Pasture Management in Temperate Agriculture. Burleigh Dodds Science Publishing Limited, 2018.
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7
Collins, Rosemary, e Athole Marshall. Improving Grassland and Pasture Management in Temperate Agriculture. Burleigh Dodds Science Publishing Limited, 2019.
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8
Collins, Rosemary, e Athole Marshall. Improving Grassland and Pasture Management in Temperate Agriculture. Burleigh Dodds Science Publishing Limited, 2019.
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9
Wheeler, J. L. Temperate Pastures: Their Production, Use and Management (Australian Wool Corporation Technical Publication). CSIRO Publishing, 1987.
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Marshall, Athole. Improving grassland and pasture management in temperate agriculture. Burleigh Dodds Science Publishing, 2018. http://dx.doi.org/10.1201/9781351114561.
Testo completoCapitoli di libri sul tema "Temperate pastures"
1
Reed, K. F. M., M. J. Mathison e E. J. Crawford. "The Adaptation, Regeneration, and Persistence of Annual Legumes in Temperate Pasture". In Persistence of Forage Legumes, 69–89. Madison, WI, USA: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/1989.persistenceofforagelegumes.c6.
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Spangenberg, German, Michael Emmerling, Ulrik John, Roger Kalla, Angela Lidgett, Eng K. Ong, Tim Sawbridge e Tracie Webster. "Transgenesis and Genomics in Molecular Breeding of Temperate Pasture Grasses and Legumes". In Plant Biotechnology 2002 and Beyond, 497–502. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-2679-5_103.
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Mabhuye, Edmund B., e Pius Z. Yanda. "Locally based responses to impacts of climate change in pastoral landscapes of Northern Tanzania." In Climate change impacts and sustainability: ecosystems of Tanzania, 101–21. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242966.0101.
Testo completoAbstract (sommario):
Abstract The impacts of climate change and variability have manifested themselves throughout the world, but considerable temporal and spatial variations exist across various places and countries. Given the variation in vulnerability, this study was undertaken in pastoral landscapes in northern Tanzania to assess the impacts of climate change, adaptation strategies and their implications to communities' livelihoods and ecosystem integrity. It examined: (i) climate trends and associated impacts on communities' livelihood options; (ii) climate change coping and adaptation strategies adopted by selected communities to reduce the severity of climate change impacts; and (iii) the challenges associated with climate change adaptation strategies in the pastoral landscape. Primary data were collected using household surveys, interviews with key informants, focus group discussions, direct field observation using transect walks and institutional analysis. Secondary data were obtained through documentary review and theme-content analysis. Results indicate that there are slight increases in temperature and wind speed as well as decreasing trends and erratic patterns of rainfall which cause drought and extended dry spells. Fluctuation in temperature and rainfall patterns affects livestock keeping through recurrent drought that has negative implications on pasture and water availability. Communities are responding to the changes through traditional response mechanisms and have embraced a few new adaptation strategies against these climate extremes, particularly drought. Generally, strategies for adaptation are likely to be successful in the near future, subject to review and harmonization of policies, institutional and legal frameworks to harness existing opportunities for management of natural resources for sustainable development and build the long-term balance between ecosystem integrity and human needs.
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Beinart, William, e Lotte Hughes. "Sheep, Pastures, and Demography in Australia". In Environment and Empire. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199260317.003.0011.
Testo completoAbstract (sommario):
Succeeding phases of British economic growth prompted strikingly different imperatives for expansion, for natural resource exploitation, and for the social organization of extra-European production. In the eighteenth century, sugar, African slaves, and shipping in the Atlantic world provided one major dynamic of empire. But in the nineteenth century, antipodean settlement and trade, especially that resulting from expanding settler pastoral frontiers, was responsible for some of the most dramatic social and environmental transformations. Plantations occupied relatively little space in the new social geography of world production. By contrast, commercial pastoralism, which took root most energetically in the temperate and semi-arid regions of the newly conquered world, was land-hungry but relatively light in its demands for labour. The Spanish Empire based in Mexico can be considered a forerunner. By the 1580s, within fifty years of their introduction, there were an estimated 4.5 million merino sheep in the Mexican highlands. The livestock economy, incorporating cattle as well as sheep, spread northwards through Mexico to what became California by the eighteenth century. Settler intrusions followed in the vast landmasses of southern Latin America, southern Africa, Australia, and New Zealand. Australia was one of the last-invaded of these territories, and, in respect of the issues that we are exploring, was in some senses distinctive. Unlike Canada and South Africa, there was no long, slow period of trade and interaction with the indigenous population; like the Caribbean, the Aboriginal people were quickly displaced by disease and conquest. The relative scale of the pastoral economy was greater than in any other British colony. Supply of meat and dairy products to rapidly growing ports and urban centres was one priority for livestock farmers. Cattle ranching remained a major feature of livestock production in Australia. Bullock-carts, not dissimilar to South African ox-wagons, were essential for Australian transport up to the 1870s. But for well over a century, from the 1820s to the 1950s and beyond, sheep flooded the southern lands. Although mutton became a significant export from New Zealand and South America, wool was probably the major product of these pastoral hinterlands—and a key focus of production in Australia and South Africa. The growth in antipodean sheep numbers was staggering.
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W. Alison, Montgomery, William D. Pitman, Glen E. Aiken e Kun-Jun Han. "Potential for Use of a Perennial C3 Grass in a Warm-Temperate Region with Pastures Dominated by C4 Grasses". In Grasses as Food and Feed. IntechOpen, 2018. http://dx.doi.org/10.5772/intechopen.79231.
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Casler, Michael D., e Daniel J. Undersander. "Identification of Temperate Pasture Grasses and Legumes". In Horse Pasture Management, 11–35. Elsevier, 2019. http://dx.doi.org/10.1016/b978-0-12-812919-7.00002-0.
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"Biological weed control in temperate grasslands". In Improving grassland and pasture management in temperate agriculture, 303–44. Burleigh Dodds Science Publishing, 2019. http://dx.doi.org/10.1201/9781351114561-15.
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Bourdôt, Graeme W., e Michael G. Cripps. "Biological weed control in temperate grasslands". In Improving grassland and pasture management in temperate agriculture, 283–324. Burleigh Dodds Science Publishing, 2018. http://dx.doi.org/10.19103/as.2017.0024.14.
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"Balancing pasture productivity with environmental and animal health requirements". In Improving grassland and pasture management in temperate agriculture, 257–72. Burleigh Dodds Science Publishing, 2019. http://dx.doi.org/10.1201/9781351114561-12.
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"Planning and sowing grasslands Shannon Williams and Sarah Baker, University of Idaho, USA". In Improving grassland and pasture management in temperate agriculture, 145–90. Burleigh Dodds Science Publishing, 2019. http://dx.doi.org/10.1201/9781351114561-8.
Testo completoAtti di convegni sul tema "Temperate pastures"
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"Impacts of a two degree increase in temperature on pasture growth in the Northern Tablelands of New South Wales". In 19th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc., 2011. http://dx.doi.org/10.36334/modsim.2011.b1.powell.
Testo completoRapporti di organizzazioni sul tema "Temperate pastures"
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Leis, Sherry, e Lloyd Morrison. Plant community trends at Tallgrass Prairie National Preserve: 1998–2018. National Park Service, ottobre 2022. http://dx.doi.org/10.36967/2294512.
Testo completoAbstract (sommario):
The Heartland Inventory and Monitoring Network monitors plant communities at Tallgrass Prairie National Preserve and evaluates a variety of environmental variables that affect vegetation patterns, including climate and ecological disturbances such as fire and grazing. Here we report on 2002–2018 trends in management actions (fire and grazing) and key plant community indicators. Temperature has increased over the past 50 years in the region. Precipitation and a standardized precipitation-evapotranspiration index included a high degree of interannual variability and did not demonstrate directional change. We documented a decline in disturbance intensity (i.e., less frequent prescribed fire and lower stocking rates) since 2006. A preserve goal is to maintain 30 to 60% of the area as bare ground (soil and rock) for ideal greater prairie-chicken habitat. Bare areas have been in decline and minimally meet the goal preserve wide. Bare areas vary by pasture and year, with bare areas exceeding the threshold in earlier years and Big Pasture and Red House Pasture falling short in some recent years. Although the preserve-scale mean minimally met the objective, there was a great deal of heterogeneity across monitoring sites. Litter cover and depth were greater than ecological recommendations for the greater prairie-chicken, especially in 2018. Litter depth demonstrated a great deal of variability and included deep litter. Woody plants were targeted to remain below 5% cover. Preserve- and pasture-scale cover means were well below this threshold but are increasing. Species richness on a per site basis (alpha diversity) and preserve-wide richness (gamma diversity) showed no apparent directional change when corrected for differences in sample size. Comparison of native species composition between 2002 and 2018 revealed a 36.9% difference in the Sørensen Index, although observer error accounted for almost 2/3 of this apparent change. The preserve continues to have characteristic tallgrass prairie species, and nonnative species continue to be low. Similar to targeted invasive plant monitoring, we found the target species Kentucky bluegrass to be below park thresholds. Continued evaluation of fire frequency and grazing intensity will be critical to achieving ecological goals including conserving the greater prairie-chicken. Development of a grazing plan may assist with prescribing stocking rates that are consistent with the preserve’s ecological and cultural objectives and could include alternative herbivores, such as goats or expansion of bison.
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Schwarte, Kirk A., e James R. Russell. Microclimate Effects on the Temperature/Spatial Distribution of Beef Cows Grazing Cool-Season Grass Pastures by Different Management Practices (A Progress Report). Ames (Iowa): Iowa State University, gennaio 2009. http://dx.doi.org/10.31274/ans_air-180814-612.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman e Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, aprile 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
Testo completoAbstract (sommario):
Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.