Managing for rainfall variability: impacts of grazing strategies on perennial grass dynamics in a dry tropical savanna

2011 ◽  
Vol 33 (2) ◽  
pp. 209 ◽  
Author(s):  
D. M. Orr ◽  
P. J. O'Reagain
Keyword(s):  
Carrying Capacity ◽  
Rainfall Variability ◽  
Perennial Grasses ◽  
Heteropogon Contortus ◽  
Heavy Grazing ◽  
Average Rainfall ◽  
Sustainable Grazing ◽  
Grazing Strategies ◽  
The Impact

Rainfall variability remains a major challenge to sustainable grazing management in northern Australia with perennial grasses the key to the stability of the resources that maintain a sustainable grazing industry. This paper describes the dynamics of five perennial grasses – Bothriochloa ewartiana (Domin) C.E. Hubb., Chrysopogon fallax S.T. Blake, Aristida spp., Panicum effusum R. Br. and Heteropogon contortus (L.) P. Beauv. ex Roem. & Schult. in relation to three grazing strategies – moderate stocking at long-term carrying capacity, heavy stocking and rotational wet season spelling. The research was conducted in permanent quadrats on the predominant land type in an extensive grazing study in an Aristida-Bothriochloa pasture in north Australia between 1998 and 2010. Summer rainfall was above average for two periods – 1998 – 2001 and 2008 – 2010 with drought and below-average rainfall from 2002 to 2007. Low rainfall affected the dynamics of all grasses by reducing survival and basal area through its effect on plant size; this impact was most noticeable for the shorter-lived Aristida spp., P. effusum and H. contortus. The impact of grazing was greatest on the long-lived B. ewartiana and C. fallax; this effect was accentuated by the 2002–07 drought. Heavy grazing during this period further reduced the survival and size of B. ewartiana in comparison with the moderate stocking and rotational spell treatments. In contrast, the survival of C. fallax was reduced in the moderate stocking and rotational spelling treatment during drought, relative to that under heavy grazing. The density of B. ewartiana declined even under moderate grazing and despite two sequences of above-average rainfall because seedling recruitment failed to offset mature plant death. Results from this study emphasised the importance of maintaining the existing populations of key long-lived species such as B. ewartiana through good management. These results also supported the overall findings from the grazing study indicating that stocking at the long-term carrying capacity is sustainable in managing for climate variability.

scholarly journals Entre 117 e 1344: qual o limite diário recomendável para a visitação da caverna Santana (PETAR-SP)?

2017 ◽  
Vol 10 (3) ◽  
Author(s):  
Heros Augusto Santos Lobo
Keyword(s):  
Carrying Capacity ◽  
Secondary Data ◽  
Natural Protected Areas ◽  
Current Limit ◽  
Show Caves ◽  
Monitoring Protocols ◽  
The Impact ◽  
Capacity Method ◽  
Made In

A capacidade de carga turística (CCT) é um conceito amplamente utilizado na gestão do turismo em áreas naturais. Em cavernas turísticas brasileiras, a CCT vem sendo utilizada quase que unicamente para limitar a quantidade diárias de visitas em uma caverna. Na caverna Santana, diferentes limites diários de visitação foram obtidos em estudos desta natureza, trazendo incerteza para a gestão do atrativo. O objetivo deste artigo é apresentar uma análise dos estudos de CCT realizados na caverna Santana, com base em revisão bibliográfica e documental e focando nos métodos utilizados, bem como suas lacunas e os resultados obtidos. Os resultados evidenciaram uma variação significativa nos estudos de CCT da caverna Santana, com limites diários de 117, 132, 135, 242, 270, 327, 378 e 1344 visitas por dia. Três destes resultados foram obtidos com o uso de métodos desenvolvidos especificamente para a caverna Santana (327, 378 e 1344 visitas/dia). Por outro lado, nenhum destes resultados foi validado com o uso de monitoramentos de longo prazo do ambiente cavernícola em relação aos impactos da visitação. Considerando os aspectos analisados pesquisa, as conclusões recomendam que o limite atual de 117 visitas/dia seja alterado por outro mais bem ajustado à realidade ambiental e social desta caverna turística. O limite atual deve ser substituído pelo resultado obtido no estudo mais preciso sobre CCT realizado na caverna – 378 visitas/dia –, bem como devem ser estabelecidos protocolos de monitoramento das principais variáveis recomendadas no método de capacidade de carga do Plano de Manejo Espeleológico da caverna: temperatura do ar, dióxido de carbono e a distribuição da fauna subterrânea. Estas modificações sugeridas poderão ajudar aos pesquisadores e gestores na obtenção de uma resposta mais acurada sobre os limites de visitação da caverna Santana. Between 117 and 1344: what is the tourist carrying capacity of Santana cave (PETAR, SP, Brazil)? ABSTRACT Tourist carrying capacity (TCC) is a concept widely applied to management of tourism in natural areas. In Brazilian show caves, TCC is used just to limit the daily number of visitors. In Santana cave, different limits of visitors were obtained in several studies, giving uncertainty to the cave managers. The purpose of this article is to show an analysis of all studies about TCC in Santana cave, based in secondary data and focusing in the used methods and related gaps and results of each research. The results show a range of variation of 117, 132, 135, 242, 270, 327, 378 and 1344 visitors per day in Santana cave. Three of these numbers were obtained using methods that were developed specifically to Santana cave (327, 378 and 1344 visitors/day). Otherwise, any of these limits were still analyzed using long-term monitoring of environment in relation to the impact of visitors. Considering this, it was recommended to change the present daily limit of 117 visitors/day for another one which gives a better adjustment with the environmental and social aspects of this show cave. The current limit should be replaced for the result obtained in the most accurate study made in the cave – 378 visitors/day – and establish monitoring protocols of the main variables recommended in the carrying capacity method of the Plan of Speleological Management of the cave: air temperature, carbon dioxide and subterranean fauna distribution. These modifications could help the researchers and managers to improve the answer to the question about the limit of visitation of Santana cave. KEYWORDS: Ecotourism; Tourism in Caves; Tourist Carrying Capacity; Show Caves; Natural Protected Areas.

Demography of three perennial grasses in a central Queensland eucalypt woodland

2009 ◽  
Vol 31 (4) ◽  
pp. 427 ◽  
Author(s):  
P. Jones ◽  
P. Filet ◽  
D. M. Orr
Keyword(s):  
Life Span ◽  
Seedling Recruitment ◽  
Negative Impact ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Seasonal Rainfall ◽  
Severe Drought ◽  
Heteropogon Contortus ◽  
Heavy Grazing ◽  
Eucalypt Woodland

The population dynamics of the palatable, perennial grasses Bothriochloa ewartiana (Domin) C.E.Hubb. (desert Mitchell grass), Chrysopogon fallax S.T.Blake (golden beard grass) and Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. (black speargrass), were studied in an extensive grazing study conducted in a eucalypt woodland within the Aristida–Bothriochloa pasture community in central Queensland between 1994 and 2000. Treatments were three grazing pressures based on light, medium and heavy utilisation of forage available at the end of summer and two timber treatments (trees intact and trees killed). Seasonal rainfall throughout this study was generally favourable for plant growth with no severe drought periods. Grazing pressure had a greater overall impact on plant dynamics than timber treatment, which had minimal impact. Grazing pressure had a large impact on H. contortus dynamics, an intermediate impact on B. ewartiana and no impact on C. fallax. Fluctuations in plant density of both B. ewartiana and C. fallax were small because both species were long lived with low levels of seedling recruitment and plant death, whereas fluctuations in H. contortus density were relatively high because of its relatively short life span and higher levels of both recruitment and death. Heavy grazing pressure increased the recruitment of B. ewartiana and H. contortus in some years but had no impact on that of C. fallax. Heavy grazing pressure reduced the survival of the original plants of both B. ewartiana and H. contortus but not of C. fallax. For H. contortus, the size of the original plants was larger where trees were killed than where trees were left intact and plants of the 1995 seedling cohort were larger in 1998 at heavy compared with those at light and medium grazing pressure. Grazing had a minor negative impact on the soil seed bank of H. contortus. Populations of all three species remained stable throughout this study, although the favourable seasonal rainfall experienced and the short duration of this study relative to the life span of these species may have masked longer term, deleterious impacts of heavy grazing pressure.

scholarly journals Sustainable grazing management for temporal and spatial variability in north Australian rangelands – a synthesis of the latest evidence and recommendations

2014 ◽  
Vol 36 (3) ◽  
pp. 223 ◽  
Author(s):  
Peter O'Reagain ◽  
Joe Scanlan ◽  
Leigh Hunt ◽  
Robyn Cowley ◽  
Dionne Walsh
Keyword(s):  
Key Management ◽  
Rainfall Variability ◽  
Grazing Management ◽  
Economic Modelling ◽  
Infrastructure Development ◽  
Northern Australia ◽  
Wet Season ◽  
Sustainable Grazing ◽  
Patch Burning

Rainfall variability is a major challenge to sustainable grazing management in northern Australia, with management often complicated further by large, spatially-heterogeneous paddocks. This paper presents the latest grazing research and associated bio-economic modelling from northern Australia and assesses the extent to which current recommendations to manage for these issues are supported. Overall, stocking around the safe long-term carrying capacity will maintain land condition and maximise long-term profitability. However, stocking rates should be varied in a risk-averse manner as pasture availability varies between years. Periodic wet-season spelling is also essential to maintain pasture condition and allow recovery of overgrazed areas. Uneven grazing distributions can be partially managed through fencing, providing additional water-points and in some cases patch-burning, although the economics of infrastructure development are extremely context-dependent. Overall, complex multi-paddock grazing systems do not appear justified in northern Australia. Provided the key management principles outlined above are applied in an active, adaptive manner, acceptable economic and environmental outcomes will be achieved irrespective of the grazing system applied.

How hot? How often? Getting the fire frequency and timing right for optimal management of woody cover and pasture composition in northern Australian grazed tropical savannas. Kidman Springs Fire Experiment 1993–2013

2014 ◽  
Vol 36 (4) ◽  
pp. 323 ◽  
Author(s):  
Robyn A. Cowley ◽  
Mark H. Hearnden ◽  
Karen E. Joyce ◽  
Miguel Tovar-Valencia ◽  
Trisha M. Cowley ◽  
...  
Keyword(s):  
Fire Regime ◽  
Vegetation Type ◽  
Fire Frequency ◽  
Perennial Grasses ◽  
Tropical Savannas ◽  
Heteropogon Contortus ◽  
Pasture Degradation ◽  
Annual Grasses ◽  
Woody Cover ◽  
The Impact

A long-term (1993–2013) experiment in grazed semiarid tropical savannas in northern Australia tested the impact of varying the frequency (every 2, 4 and 6 years) and season (June – EDS versus October – LDS) of fire compared with unburnt controls on woody cover and pasture composition, in grassland and open woodland. Over an 18-year period, woody cover increased by 4% (absolute) in the woodland even with the most severe (i.e. frequent, late dry season) fire treatments. With less severe or no fire, woody cover increased by 12–17%. In the grassland, woody cover remained static when subjected to LDS fires every 2 or 4 years, but increased by 3–6% under other fire treatments, and by 8% when unburnt. Major shifts in understorey species composition occurred at both sites regardless of fire regime. The effect of fire on herbage mass and composition was compounded by higher grazing after fires. The herbage mass of perennial grasses declined and that of annual grasses and forbs increased following early or frequent fires. Brachyachne convergens, Gomphrena canescens and Flemingia pauciflora increased in response to fire while Aristida latifolia and Heteropogon contortus decreased. Four-yearly LDS fire provided the most effective management of woody cover and pasture composition. Although EDS fire is recommended for biodiversity management and reducing greenhouse gas emissions in wet tropical savannas, on grazed pastoral land, it can promote woodland thickening and pasture degradation. Optimal fire management, therefore, depends on vegetation type, land use and the prevailing seasonal timing and frequency of fire.

Comparing fixed and flexible stocking as adaptations to inter-annual rainfall variability in the extensive beef industry of northern Australia

2016 ◽  
Vol 38 (1) ◽  
pp. 85 ◽  
Author(s):  
Lester Pahl ◽  
Joe Scanlan ◽  
Giselle Whish ◽  
Robyn Cowley ◽  
Neil MacLeod
Keyword(s):  
Carrying Capacity ◽  
Rainfall Variability ◽  
Full Range ◽  
Herd Size ◽  
Annual Rainfall ◽  
Northern Australia ◽  
Beef Industry ◽  
Growing Seasons ◽  
Stocking Rates

Many beef producers within the extensive cattle industry of northern Australia attempt to maintain a constant herd size from year-to-year (fixed stocking), whereas others adjust stock numbers to varying degrees annually in response to changes in forage supply. The effects of these strategies on pasture condition and cattle productivity cannot easily be assessed by grazing trials. Simulation studies, which include feedbacks of changes to pasture condition on cattle liveweight gain, can extend the results of grazing trials both spatially and temporally. They can compare a large number of strategies, over long periods of time, for a range of climate periods, at locations which differ markedly in climate. This simulation study compared the pasture condition and cattle productivity achieved by fixed stocking at the long-term carrying capacity with that of 55 flexible stocking strategies at 28 locations across Queensland and the Northern Territory. Flexible stocking strategies differed markedly in the degree they increased or decreased cattle stocking rates after good and poor pasture growing seasons, respectively. The 28 locations covered the full range in average annual rainfall and inter-annual rainfall variability experienced across northern Australia. Constrained flexibility, which limited increases in stocking rates after good growing seasons to 10% but decreased them by up to 20% after poor growing seasons, provides sustainable productivity gains for cattle producers in northern Australia. This strategy can improve pasture condition and increase cattle productivity relative to fixed stocking at the long-term carrying capacity, and its capacity to do this was greatest in the semiarid rangeland regions that contain the majority of beef cattle in northern Australia. More flexible stocking strategies, which also increased stocking rates after good growing seasons by only half as much as they decreased them after poor growing seasons, were equally sustainable and more productive than constrained flexibility, but are often impractical at property and industry scales. Strategies with the highest limits (e.g. 70%) for both annual increases and decreases in stocking rates could achieve higher cattle productivity, but this was at the expense of pasture condition and was not sustainable. Constrained flexible stocking, with a 10% limit for increases and a 20% limit for decreases in stocking rates annually, is a risk-averse adaptation to high and unpredictable rainfall variability for the extensive beef industry of northern Australia.

scholarly journals Rainfall diagnosis in context of cereal yields in Gujarat

MAUSAM ◽  
2021 ◽  
Vol 67 (4) ◽  
pp. 919-926
Author(s):  
DEEPA B. HIREMATH ◽  
R. L. SHIYANI ◽  
K. K. DAKHORE
Keyword(s):  
Agricultural Production ◽  
Management Practices ◽  
Rainfall Variability ◽  
Insurance Coverage ◽  
Mitigation Strategies ◽  
Annual Average ◽  
Climatic Zones ◽  
Average Rainfall ◽  
The Impact ◽  
Cereal Yields

The present study was undertaken to analyze annual average rainfall in Gujarat in order to classify and define the targeted zones and to know the impact of rainfall variability on agriculture in the state. The results revealed that the Northwest Agro-climatic zone was the most vulnerable zone among all the agro-climatic zones due to extreme deviations in rainfall pattern. This was followed by north Saurashtra, South saurashtra and Middle Gujarat Zone. The southern hills zone had the least per cent of years with extreme deviations. Water management practices such as drip irrigation, deepening wells, constructing check-dams; integrated watershed management as well as insurance coverage and microfinancing facilities have been suggested as mitigation strategies to overcome the adverse impact of rainfall variability on agricultural production.  

scholarly journals Tropical Rainfall Variability on Interannual-to-Interdecadal and Longer Time Scales Derived from the GPCP Monthly Product

2007 ◽  
Vol 20 (15) ◽  
pp. 4033-4046 ◽  
Author(s):  
Guojun Gu ◽  
Robert F. Adler ◽  
George J. Huffman ◽  
Scott Curtis
Keyword(s):  
Rainfall Variability ◽  
Volcanic Eruptions ◽  
Linear Change ◽  
Tropical Ocean ◽  
Tropical Rainfall ◽  
Enso Events ◽  
Time Period ◽  
The Tropics ◽  
The Impact

Abstract Global and large regional rainfall variations and possible long-term changes are examined using the 27-yr (1979–2005) Global Precipitation Climatology Project (GPCP) monthly dataset. Emphasis is placed on discriminating among variations due to ENSO, volcanic events, and possible long-term climate changes in the Tropics. Although the global linear change of precipitation in the dataset is near zero during the time period, an increase in tropical rainfall is noted in the dataset, with a weaker decrease over Northern Hemisphere middle latitudes. Focusing on the Tropics (25°S–25°N), the dataset indicates an upward linear change (0.06 mm day−1 decade−1) and a downward linear change (−0.01 mm day−1 decade−1) over tropical ocean and land, respectively. This corresponds to an about 5.5% increase (ocean) and 1% decrease (land) during the entire 27-yr time period. The year 2005 has the largest annual tropical total precipitation (land plus ocean) for the GPCP record. The five highest years are (in descending order) 2005, 2004, 1998, 2003, and 2002. For tropical ocean the five highest years are 1998, 2004, 2005, 2002, and 2003. Techniques are applied to isolate and quantify variations due to ENSO and two major volcanic eruptions during the time period (El Chichón, March 1982; Mount Pinatubo, June 1991) in order to examine longer-time-scale changes. The ENSO events generally do not impact the tropical total rainfall, but rather induce significant anomalies with opposite signs over tropical land and ocean. The impact of the two volcanic eruptions is estimated to be about a 5% reduction in tropical rainfall over both land and ocean. A modified dataset (with ENSO and volcano effects removed) retains the same approximate linear change slopes, but with reduced variances, thereby increasing the statistical significance levels associated with the long-term rainfall changes in the Tropics. However, although care has been taken to ensure that this dataset is as homogeneous as possible, firm establishment of the existence of the discussed changes as long-term trends may require continued analysis of the input datasets and a lengthening of the observation period.

scholarly journals Managing for rainfall variability: long-term profitability of different grazing strategies in a northern Australian tropical savanna

2011 ◽  
Vol 51 (3) ◽  
pp. 210 ◽  
Author(s):  
Peter O'Reagain ◽  
John Bushell ◽  
Bill Holmes
Keyword(s):  
Sustainable Management ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Seasonal Forecasts ◽  
Variable Environment ◽  
Poor Condition ◽  
Product Value ◽  
Grazing Strategies ◽  
Stocking Rates

Several grazing strategies are recommended to manage sustainably for rainfall variability in northern Australia, but there is little objective data on their profitability relative to less sustainable management systems such as heavy stocking. In 1997, a large cattle grazing trial was initiated in northern Queensland to quantify the relative performance of a range of grazing strategies in a variable climate. These strategies were (i) moderate stocking (MSR) stocked at the calculated long-term carrying capacity (LTCC), (ii) heavy stocking (HSR) at twice LTCC, (iii) rotational wet-season spelling (R/Spell) at 1.5 LTCC, (iv) variable stocking (VAR), with stocking rates adjusted in May based on available forage and (v) a southern oscillation index (SOI)-variable strategy, with stocking rates adjusted in November based on available forage and SOI-based seasonal forecasts. Rainfall varied over the 12-year trial period, with sequences of dry and wet years. Gross margins (GM) in the HSR were initially high but collapsed in drier years due to high costs and reduced product value. GMs only recovered in later years with a reduced stocking rate and increased rainfall. The VAR and SOI were also initially very profitable, but GMs plunged as rainfall declined due to reduced animal performance and the sale of poor-condition cattle. This sharp cut in stocking rates nevertheless allowed GMs to recover well in subsequent years. In the MSR, GMs remained relatively constant across most years due to low costs and a higher product value. The R/Spell also performed relatively well despite being compromised by an ill-timed fire, drought and the subsequent sale of poor-condition cattle. Net present value (NPV) after 12 years was highest in the VAR ($11 962/100 ha), followed by the MSR ($11 873/100 ha), the SOI ($11 167/100 ha) and the R/Spell ($10 665/100 ha). NPV was by far the lowest in the HSR ($6930/100 ha). Profitability also varied the most in the HSR, with a negative GM in 6 of the 12 years. Incorporating the costs of natural resource decline would further reinforce the case against heavy stocking. These results challenge the assumption that sustainable management in a variable environment is unprofitable.

scholarly journals 137Cs accumulation in the yield of agricultural crops depending on the impact of agrochemical factors

2016 ◽  
pp. 140-145
Author(s):  
O. Stupenko ◽  
P. Vytrykhovs’kyy ◽  
V. Hirnyk
Keyword(s):  
Carbohydrate Metabolism ◽  
Crop Yields ◽  
Sandy Soils ◽  
Perennial Grasses ◽  
Nitrogen Fertilizers ◽  
Agricultural Crops ◽  
Phosphorus And Potassium ◽  
The Impact ◽  
Flax Crop

We summarized the results of long-term research of fertili zing system and chemical melioration on radio cesium transition info yield of agricultural crops. The effect of such heavy fertilizer elements as magnesium and sulfur, participating in the nitrogen, phosphoric and carbohydrate metabolism in plants, on the crop formation and quality is studied. The influence of liming, level of providing soil with phosphorus and potassium, doses of nitrogen fertilizers in top-dressing, on buildup of radionuclide in crop yields is shown. The influence of the complex nitrogen-free fertilizer «Ekoplant» and its inclusion doses on the straw flax crop is defined. It has been shown the possibility of using the angustifolins lupine on sod-podzolic sandy soils with 10 Ci/km2 radio cesium contamination. It has been shown the dependence of radionuclide accumulation on perennial grasses hay harvest that were grown on sod-podzolic sandy soils of Polissia with 10 Ci/km2 radio cesium contamination.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

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