Vegetation changes in a semiarid tropical savanna, northern Australia: 1973 - 2002

2003 ◽  
Vol 25 (1) ◽  
pp. 3 ◽  
Author(s):  
Gary Bastin ◽  
John Ludwig ◽  
Robert Eager ◽  
Adam Liedloff ◽  
Reginald Andison ◽  
...  
Keyword(s):  
Vegetation Change ◽  
Experimental Studies ◽  
Cattle Grazing ◽  
Dry Season ◽  
Perennial Grasses ◽  
Calotropis Procera ◽  
Research Station ◽  
Vegetation Changes ◽  
Northern Australia ◽  
Heteropogon Contortus

We measured vegetation changes inside and outside two exclosures built in 1973 on red calcareous loam soils located in Conkerberry Paddock on Victoria River Research Station in northern Australia. These two exclosures were unburnt since their establishment in 1973 until exclosure 1 was unintentionally burnt late in the dry season (October) of 2001. Data from permanent transects and examples from photopoints illustrate that from mostly bare soils in 1973, total pasture biomass recovered relatively rapidly both inside and outside exclosures (in about five years). This initial recovery was primarily due to the establishment of annual grasses and forbs. After this five year period, there was a consistent increase in the biomass of perennial grasses, such as Heteropogon contortus and Dichanthium spp. Also in the first five years after exclosure, the exotic shrub, Calotropis procera,invaded the study area, but then largely disappeared in a period of lower wet-season rainfall in the late 1980s. The density of native tree species, particularly Hakea arborescens, Eucalyptus pruinosa and Lysiphyllum cunninghamii increased in general, but more so inside one or other of the exclosures. Although the late dry-season fire of 2001 reduced the density of larger H. arborescens and L. cunninghamii inside the exclosure at Site 1, this effect was not apparent for smaller trees and for trees outside this exclosure. Our findings show that savanna vegetation can change massively in the medium term (29 years) and that exclosure from cattle grazing can contribute to our understanding of the role of livestock in such change. However, exclosures by themselves do not provide adequate information about the processes leading to vegetation change replicated experimental studies are needed. That substantial increase in the biomass and proportion of perennial grasses occurred with light to moderate cattle grazing implies that these rangelands can be managed for production, although control of woody vegetation is an issue.

Frequency and season of fires varies with distance from settlement and grass composition in Eucalyptus miniata savannas of the Darwin region of northern Australia

2009 ◽  
Vol 18 (1) ◽  
pp. 61 ◽  
Author(s):  
Louis P. Elliott ◽  
Donald C. Franklin ◽  
David M. J. S. Bowman
Keyword(s):  
Fire History ◽  
Fire Suppression ◽  
Fire Frequency ◽  
Dry Season ◽  
Perennial Grasses ◽  
Northern Australia ◽  
Landsat Images ◽  
Fire Cycle ◽  
Annual Grasses ◽  
Key Issues

In savanna environments, fire and grass are inextricably linked by feedback loops. In the Darwin area of northern Australia, flammable tall annual grasses of the genus Sarga (previously Sorghum1) have been implicated in a savanna fire-cycle. We examined the relationship between fire history, the grass layer and distance from settlement using LANDSAT images and plot-based surveys. Areas more than 500 m from settlement were burnt almost twice as often, the additional fires being concentrated late in the dry season and in areas dominated by annual Sarga and even more so where dominated by short annual grasses. Grass cover was a stronger correlate of fire frequency than grass biomass, the two showing a non-linear relationship. Sites dominated by short annual grasses had similar cover to, but markedly lower biomass than those dominated by annual Sarga or perennial grasses. Our results reflect the success of fire suppression in the vicinity of settlements, but little effective management of late dry-season wildfires in remoter areas. We evaluate several hypotheses for the association of frequent fire with annual grasses regardless of their growth form and conclude that fuel connectivity and possibly other fuel characteristics are key issues worthy of further investigation.

Grazing Management Strategies for Reseeded Rangelands in the East Kimberley Region of Western Australia.

1991 ◽  
Vol 13 (1) ◽  
pp. 14 ◽  
Author(s):  
RB Hacker ◽  
SB Tunbridge
Keyword(s):  
Management System ◽  
Management Strategies ◽  
Dry Season ◽  
Perennial Grasses ◽  
Grazing Management ◽  
Research Station ◽  
Stocking Rate ◽  
Perennial Species ◽  
Wet Season ◽  
Continuous Grazing

Grazing management strategies involving continuous grazing, wet season rest, dry season rest and a range of stocking rates of steers were evaluated on reseeded rangeland at Ord Regeneration Research Station by the use of temporary exclosures within continuously grazed paddocks. The rangeland is a patchwork of plant communities in various stages of regeneration. Under continuous grazing, liveweight gain in three of the four years of the trial was more closely related to botanical differences between paddocks than to stocking rate although all paddocks were confined to the one land unit. Animals generally selected those parts of the pasture where regeneration of perennial grasses was least advanced and the vegetation was characterized by short annual and semi-perennial species. Differences in the yield of these species between paddocks accounted for much of the variation in liveweight gain. Perennial species contributed most to animal production when seasonal conditions were poor. Over the study as a whole, year-in-year-out stocking rate was much more important than management system (proportion of wet season grazing) in determining vegetation changes. Nevertheless, selective grazing of the short grass patches will prevent the use of a continuous grazing strategy in these pastures. However, continued regeneration should be feasible under a tactical management system in which grazing is managed to ensure that a minimum level of cover is maintained on the short grass phase and that the end of dry season utilization level for the key perennial species does not exceed an average (over years) of about 30 per cent.

The response of weaner cattle grazing natural pastures in north western Australia to phosphoric acid, non protein nitrogen and sulphur in their drinking water.

1981 ◽  
Vol 3 (2) ◽  
pp. 133
Author(s):  
A.McR. Holm ◽  
AL Payne ◽  
PD Morgan ◽  
EJ Speijers
Keyword(s):  
Drinking Water ◽  
Phosphoric Acid ◽  
Western Australia ◽  
Cattle Grazing ◽  
Dry Season ◽  
Research Station ◽  
Wet Season ◽  
Protein Nitrogen ◽  
Nitrogenous Compounds ◽  
North Western

The study was designed to evaluate the effects of phosphorus and non protein nitrogen supplementation on weaner cattle grazing natural pastures on the Fitzroy Pastoral Research Station, north Western Australia. The study was repeated over the period July 1971 to April 1976, with four drafts of weaners which grazed Mitchell grass pastures during the dry season and curly spinifex-ribbon grass pastures during the wet season. In each year, one of four groups received either no supplement (control), urea plus sulphuric acid, phosphoric acid, or urea plus ammonium sulphate plus phosphoric acid. The supplements were measured into and mixed with the drinking water. Weaners given phosphoric acid gained between 10.5 and 21.7 kg a head more than those not given phosphorus. The response was significant in two of the four dry seasons, three of the four wet seasons and for every ye= when both seasons were considered together. Urea supplements increased liveweight gain over the dry season and depressed liveweight gain over the wet season. There was no advantage to urea when the two seasons were combined. Cattle given supplements through the drinking water drank less water and more of those given nitrogenous compounds died than those not receiving supplements.

scholarly journals Vegetation Dynamic Assessment by NDVI and Field Observations for Sustainability of China’s Wulagai River Basin

2021 ◽  
Vol 18 (5) ◽  
pp. 2528
Author(s):  
Panpan Chen ◽  
Huamin Liu ◽  
Zongming Wang ◽  
Dehua Mao ◽  
Cunzhu Liang ◽  
...  
Keyword(s):  
Species Diversity ◽  
River Basin ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Dynamic Assessment ◽  
Indicator System ◽  
Vegetation Changes ◽  
Vegetation Dynamic ◽  
Management Policies ◽  
The Impact

Accurate monitoring of grassland vegetation dynamics is essential for ecosystem restoration and the implementation of integrated management policies. A lack of information on vegetation changes in the Wulagai River Basin restricts regional development. Therefore, in this study, we integrated remote sensing, meteorological, and field plant community survey data in order to characterize vegetation and ecosystem changes from 1997 to 2018. The residual trend (RESTREND) method was utilized to detect vegetation changes caused by human factors, as well as to evaluate the impact of the management of pastures. Our results reveal that the normalized difference vegetation index (NDVI) of each examined ecosystem type showed an increasing trend, in which anthropogenic impact was the primary driving force of vegetation change. Our field survey confirmed that the meadow steppe ecosystem increased in species diversity and aboveground biomass; however, the typical steppe and riparian wet meadow ecosystems experienced species diversity and biomass degradation, therefore suggesting that an increase in NDVI may not directly reflect ecosystem improvement. Selecting an optimal indicator or indicator system is necessary in order to formulate reasonable grassland management policies for increasing the sustainability of grassland ecosystems.

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

Effect of cattle grazing on range perennial grasses in the Mendoza plain, Argentina

1996 ◽  
Vol 34 (2) ◽  
pp. 205-213 ◽  
Author(s):  
J.C. Guevara ◽  
C.R. Stasi ◽  
O.R. Estevez
Keyword(s):  
Cattle Grazing ◽  
Perennial Grasses

scholarly journals Soil Denitrifier Community Size Changes with Land Use Change to Perennial Bioenergy Cropping Systems

2016 ◽  
Author(s):  
Karen A. Thompson ◽  
Bill Deen ◽  
Kari E. Dunfield
Keyword(s):  
Land Use ◽  
16S Rrna ◽  
Land Use Change ◽  
Crop Production ◽  
Large Scale ◽  
Perennial Grasses ◽  
N2o Emissions ◽  
Research Station ◽  
N2o Production ◽  
Nirs Gene

Abstract. Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn-soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn-soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n = 30), with miscanthus and switchgrass grown alongside corn-soybean rotations at different N rates (0 and 160 kg N ha-1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011–2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA), and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn-soybean rotations regardless of management, indicating large-scale LUC from corn-soybean to miscanthus may be suitable in variable Ontario conditions while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRA) and denitrifying communities changed differently over time and in response to LUC, indicating varying controls on these communities.

scholarly journals Simulated climate variability in the region of Rapa Nui during the last millennium

2011 ◽  
Vol 7 (1) ◽  
pp. 381-395 ◽  
Author(s):  
C. Junk ◽  
M. Claussen
Keyword(s):  
Large Scale ◽  
Vegetation Change ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Easter Island ◽  
Ice Age ◽  
Vegetation Changes ◽  
Last Millennium ◽  
Climate Data ◽  
Climatic Fluctuations

Abstract. Easter Island, an isolated island in the Southeast Pacific, was settled by the Polynesians probably between 600 and 1200 AD and discovered by the Europeans in 1722 AD. While the Polynesians presumably found a profuse palm woodland on Easter Island, the Europeans faced a landscape dominated by grassland. Scientists have examined potential anthropogenic, biological and climatic induced vegetation changes on Easter Island. Here, we analyze observational climate data for the last decades and climate model results for the period 800–1750 AD to explore potential causes for a climatic-induced vegetation change. A direct influence of the ENSO phenomenon on the climatic parameters of Easter Island could not be found in the model simulations. Furthermore, strong climatic trends from a warm Medieval Period to a Little Ice Age or rapid climatic fluctuations due to large volcanic eruptions were not verifiable for the Easter Island region, although they are detectable in the simulations for many regions world wide. Hence we tentatively conclude that large-scale climate changes in the oceanic region around Easter Island might be too small to explain strong vegetation changes on the island over the last millennium.

scholarly journals The economics of phosphorus supplementation of beef cattle grazing northern Australian rangelands

2020 ◽  
Vol 60 (5) ◽  
pp. 683
Author(s):  
M. K. Bowen ◽  
F. Chudleigh ◽  
R. M. Dixon ◽  
M. T. Sullivan ◽  
T. Schatz ◽  
...  
Keyword(s):  
Economic Benefits ◽  
Dry Season ◽  
Cattle Herd ◽  
Annual Business ◽  
Northern Australia ◽  
Wet Season ◽  
P Deficiency ◽  
Business Profit ◽  
Dry Seasons ◽  
Land Types

Context Phosphorus (P) deficiency occurs in beef cattle grazing many rangeland regions with low-P soils, including in northern Australia, and may severely reduce cattle productivity in terms of growth, reproductive efficiency and mortality. However, adoption of effective P supplementation by cattle producers in northern Australia is low. This is likely to be due to lack of information and understanding of the profitability of P supplementation where cattle are P-deficient. Aims The profitability of P supplementation was evaluated for two dissimilar regions of northern Australia, namely (1) the Katherine region of the Northern Territory, and (2) the Fitzroy Natural Resource Management (NRM) region of central Queensland. Methods Property-level, regionally relevant herd models were used to determine whole-of-business productivity and profitability over 30 years. The estimated costs and benefits of P supplementation were obtained from collation of experimental data and expert opinion of persons with extensive experience of the industry. The economic consequences of P supplementation at the property level were assessed by comparison of base production without P supplementation with the expected production of P-supplemented herds, and included the implementation phase and changes over time in herd structure. In the Katherine region, it was assumed that the entire cattle herd (breeders and growing cattle) grazed acutely P-deficient land types and the consequences of (1) no P supplementation, or P supplementation during (2) the dry season, or (3) both the wet and dry seasons (i.e. 3 scenarios) were evaluated. In the Fitzroy NRM region, it was assumed that only the breeders grazed P-deficient land types with three categories of P deficiency (marginal, deficient and acutely deficient), each with either (1) no P supplementation, or P supplementation during (2) the wet season, (3) the dry season, or (4) both the wet and dry seasons (i.e. 12 scenarios). Key results In the Katherine region, year-round P supplementation of the entire cattle herd (7400 adult equivalents) grazing acutely P-deficient pasture resulted in a large increase in annual business profit (+AU$500000). Supplementing with P (and N) only in the dry season increased annual business profit by +AU$200000. In the Fitzroy NRM region, P supplementation during any season of the breeder herd grazing deficient or acutely P-deficient pastures increased profit by +AU$2400–AU$45000/annum (total cattle herd 1500 adult equivalents). Importantly, P supplementation during the wet season-only resulted in the greatest increases in profit within each category of P deficiency, comprising +AU$5600, AU$6300 and AU$45000 additional profit per annum for marginal, deficient and acutely P-deficient herds respectively. Conclusions The large economic benefits of P supplementation for northern beef enterprises estimated in the present study substantiate the current industry recommendation that effective P supplementation is highly profitable when cattle are grazing P-deficient land types. Implications The contradiction of large economic benefits of P supplementation and the generally low adoption rates by the cattle industry in northern Australia suggests a need for targeted research and extension to identify the specific constraints to adoption, including potential high initial capital costs.

Forage production for dairy farming in terms of the Research Station “Poyma”

2021 ◽  
pp. 8-16
Author(s):  
А.А. Анисимов ◽  
П.И. Комахин ◽  
В.Н. Золотарев
Keyword(s):  
Animal Husbandry ◽  
Perennial Grasses ◽  
Research Station ◽  
Forage Production ◽  
Forage Crops ◽  
Animal Product ◽  
Advanced Experience ◽  
Stable Production ◽  
Annual Grasses ◽  
Silage Production

Важнейшей проблемой продовольственной безопасности страны является уровень обеспеченности населения молочными продуктами. В связи с этим большое значение имеет опыт работы передовых хозяйств такого профиля в определённых почвенно-климатических и природно-экологических условиях. ФГБУ «Опытная станция «Пойма» является одним из наиболее эффективных хозяйств в Московской области по производству молока. Общая площадь сельскохозяйственных угодий составляет 6135 га, из них 2000 га пашни. В структуре посевных площадей 95% и более занимают кормовые культуры, в том числе 12–14% — однолетние травы, 68–70% — многолетние травы и природные кормовые угодья, 15–16% — кукуруза на силос. Основное производство кормов сосредоточено на высокоплодородных пойменных землях, на долю которых приходится 84% кормовых угодий. В статье изложены результаты системного применения достижений науки и передового опыта по стабильному производству высококачественных объёмистых кормов. Проведён анализ состояния кормопроизводства и животноводства хозяйства с 1982 по 2020 год, освещены научные подходы к увеличению производства кормов и животноводческой продукции. Системное освоение передовых научных разработок по созданию высокопродуктивных кормовых посевов и стабильному производству высококачественных объёмистых кормов, их рациональному хранению и использованию, техническая модернизация позволили увеличить среднегодовой надой на корову с 4079 до 9708 кг, или более чем в 2,3 раза, при одновременном снижении расхода кормов на 1 кг молока с 1,37 до 0,90 корм. ед. при повышении рентабельности с 16 до 28%. Food safety of the country is highly affected by the availability of milk products. Therefore, the experience of leading farms is of great importance under certain environmental conditions. The Research Station “Poyma” is one of the leading milk producers in the Moscow region. Its fields occupy around 6135 ha. The proportion of forage crops amounts to 95% including 12–14% of annual grasses, 68–70% of perennial grasses and natural forage lands as well as 15–16% of maize for silage production. 84% of the total cultivation area are high-fertile floodlands. This article focuses on the application of the latest scientific findings and advanced experience for stable production of high-quality bulk fodder. The efficiency of forage production and Animal Husbandry was analyzed in the period from 1982 to 2020. The methods and practices were reviewed to optimize forage and animal product resources. Average annual milk yield was improved from 4079 to 9708 kg per cow, or by more than 2.3 times due to the introduction of the latest findings into the production process including the cultivation of high-productive forage crops, stabilization of bulk fodder supplies, feed effective storage and use. Forage consumption dropped from 1.37 to 0.90 feed units for the production of 1 kg of milk, payback increased from 16 to 28%.

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