Evaluating Stocking Rate Impacts in Rangelands: Animals Don't Practice What We Preach.

1996 ◽  
Vol 18 (2) ◽  
pp. 216 ◽  
Author(s):  
AJ Ash ◽  
DMS Smith
Keyword(s):  
New Zealand ◽  
Temporal Variability ◽  
Simulation Models ◽  
Animal Production ◽  
Policy Framework ◽  
Government Printing ◽  
Spatial And Temporal Variability ◽  
United States Department ◽  
Stocking Rate ◽  
The Impact

paper session 29: Molecular biology - forage quality. In: Proc. XVII International Grassland Congress, pp. 1105-6. Keeling and Mundy Ltd., Palmerston North, New Zealand. United States Department of Agriculture. (1980). Report and recommendations on organic farming. U.S. Government Printing Office, Washington, DC. VanTassel, L. W., Heitschmidt, R.K. and Conner, J.R. (1987). Modeling variation in range calf growth under conditions of environmental uncertainty. J. Range. Manage. 40: 310-4. Walker, B.H. (1993). Stability in rangelands: ecology and economics. In: Proc. XW International Grassland Congress, pp. 1885-90. Keeling and Mundy Ltd., Palmerston North, New Zealand. Walker, J.W. (1994). Multispecies grazing: the ecological advantage. Sheep Res. J. Special Issue: 52-64. Walker, A.B., Frizelle, J.A. and Morris, S.D. (1994). The New Zealand policy framework for sustainable agriculture and some implications for animal production research. Proc. N. Z. Soc. Anim Prod. 54: 369-72. Walker, J.W., Heitschmidt, R.K., DeMoraes, E.A., Kothmann, M.M. and Dowhower, S.L. (1989). Quality and botanical composition of cattle diets under rotational and continuous grazing treatments. J. Range Manage . 42: 239-42. Whitson, R.E., Heitschmidt, R.K., Kothmann, M.M. and Lundgren, G.K. (1982). The impact of grazing systems on the magnitude and stability of ranch income in the Rolling Plains of Texas. J. Range Manage .35: 526-32. Wight, J.R. and Hanson, C.L. (1993). Simulation models as decision aids for management of rangeland ecosystems. In: Proc. XVII International Grassland Congress, pp. 770-1. Keeling and Mundy Ltd., Palmerston North, New Zealand. Wilson, A.D., Harrington, G.N. and Beale, I.F. (1984). Grazing management. In: Management of Australia's rangelands (Eds G.N. Harrington, A.D. Wilson and M.D. Young) pp. 129-40. Commonwealth Scientific and Industrial Research Organization, Australia. Wood, W.R. and Thiessen, T.D. (Eds) (1985). Early fur trade on the Northern Plains: the narratives of John Macdonnell, David Thompson, Francois-Antoine Laraocque and Charles McKenzie. University of Oklahoma Press, Norman, Oklahoma. Manuscript received 4 April 1996, accepted 30 July 1996. Rangel. J. 18(2) 1996, 216-43 EVALUATING STOCKING RATE IMPACTS IN RANGELANDS: ANIMALS DON'T PRACTICE WHAT WE PREACH A.J. Ash1 and D.M. Stafford Smith2 'CSIRO Division of Tropical Crops and Pastures, PMB, Aitkenvale, Qld 4814 2CSIR0 Division of Wildlife and Ecology, PO Box 2111, Alice Springs, NT 0871 Abstract Stocking rate is the most important management variable affecting productivity and stability in rangelands. In this paper we examine the relevance of stocking rate research to the complex and highly variable ecosystems that make up most rangeland enterprises. We review a number of stocking rate experiments that have been conducted in both rangelands and more intensively grazed, improved pastures and demonstrate a fundamental difference in the nature of the stocking rate - animal production relationship between the two environments. Animal production in rangelands is less sensitive to increases in utilisation rate than in improved pastures, at least in the short to medium time frame of most experiments. These differences can largely be explained by factors relating to the much greater spatial and temporal variability of rangelands such as: inter-annual and seasonal fluctuations in vegetation composition and quality; long-term vegetation changes; and spatial and temporal patterns of diet selection in complex vegetation. Together, these factors limit the application of linear stocking rate models to complex rangeland environments for prediction of animal production responses. We suggest that dynamic simulation models, which incorporate the spatial and temporal variability of rangelands, may be the best way of developing simple but useful management principles for setting stocking rates that are more appropriate than simplified regression relationships.

scholarly journals The influence of riparian woodland on the spatial and temporal variability of stream water temperatures in an upland salmon stream

2004 ◽  
Vol 8 (3) ◽  
pp. 449-459 ◽  
Author(s):  
I. A. Malcolm ◽  
D. M. Hannah ◽  
M. J. Donaghy ◽  
C. Soulsby ◽  
A. F. Youngson
Keyword(s):  
Thermal Regime ◽  
Temporal Variability ◽  
Heat Budget ◽  
Riparian Forest ◽  
Stream Water ◽  
Spatial And Temporal Variability ◽  
Substantial Impact ◽  
Site Specific ◽  
The Impact ◽  
Riparian Woodland

Abstract. The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment), Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours) and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm

scholarly journals The influence of a new water infrastructure development on the relative abundance of two Australian freshwater turtle species

2018 ◽  
Vol 66 (1) ◽  
pp. 57 ◽  
Author(s):  
Natalie J. Clark ◽  
Courtenay E. Mills ◽  
Nicolette A. Osborne ◽  
Kerry M. Neil
Keyword(s):  
Relative Abundance ◽  
Temporal Variability ◽  
Monitoring Program ◽  
Freshwater Turtle ◽  
Spatial And Temporal Variability ◽  
Main Body ◽  
Water Infrastructure ◽  
Turtle Species ◽  
Australian Freshwater ◽  
The Impact

Development of water infrastructure benefits water security and agriculture but poses risks to habitat and aquatic fauna. Wyaralong Dam was constructed on Teviot Brook in 2010 to provide future urban water supplies for South East Queensland, Australia. Construction of the dam created a large impoundment area and environmental impact assessment predicted significant impacts upon resident freshwater turtle species and their habitats. Differences in habitat requirements, life-history characteristics and sensitivity to change between the Macquarie River turtle (Emydura macquarii macquarii) and the common saw-shelled turtle (Myuchelys latisternum) were expected to influence the impact of the dam on the spatial and temporal abundance of these species. The relative abundance of each species was monitored at sites located within, upstream and downstream of the impoundment across wet and dry seasons during the dam’s first five years of operation. The results of this monitoring program indicate that spatial and temporal variability in the relative abundance of E. macquarii macquarii and M. latisternum occurred during the study but not all expected impacts were realised. Contrary to expectation, the relative abundance of E. macquarii macquarii did not increase over time within, upstream or downstream of the dam. M. latisternum showed greater temporal variability at some sites; however, no clear relationship between relative abundance and operational years was observed during the monitoring program. Spatial variability in relative abundance between sites was dependent upon season, with trends generally consistent across both turtle species. Where differences between species were observed, these are suspected to have resulted from the influence of environmental conditions on species-specific movement behaviours. The monitoring program confirmed the use of the upper limits of the impoundment and the plunge pool below the dam wall by both turtle species but relative abundance within the main body of the impoundment remained low throughout monitoring. The results of the study allow for consideration of the suitability of predefined management measures and the development of recommendations for future monitoring programs prescribed for water infrastructure developments.

scholarly journals Approaches to evaluate spatial and temporal variability of deep marine sediment characteristics under the impact of dense water formation events

2020 ◽  
Author(s):  
XAVIER DURRIEU de MADRON ◽  
MARION STABHOLZ ◽  
LARS-ERIC HEIMBÜRGER-BOAVIDA ◽  
DOMINIQUE AUBERT ◽  
PHILIPPE KERHERVÉ ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Temporal Variability ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Geochemical Composition ◽  
Dense Water ◽  
Water Formation ◽  
Dense Water Formation ◽  
Northwestern Mediterranean Sea ◽  
The Impact

Dense shelf water cascading and open-ocean convection frequently occurs in the Gulf of Lions, northwestern Mediterranean Sea. These intense dense water formation events are capable of supplying large amounts of particulate matter as well as remobilizing and dispersing local sediments and, therefore, are thought to leave an imprint on superficial deposits. Here, we compared the spatial variability of the superficial sediment composition (grain size, organic parameters, and metals) at different scales (from decimetric to kilometric) on the continental slope and rise with the temporal variability linked to the occurrence of intense dense water formation events. The spatial and temporal variability of the geochemical composition of deep sediments was assessed using multivariate and geostatistical analysis. The results indicate that, on the outer reach of the Cap de Creus Canyon, where both processes interact, no clear relation was found between the temporal variability of the superficial sediment and the deep-water formation events, and that the small-scale spatial variability of the sediment is masking the temporal variability. Measurements across the southern slope indicate the presence of a somehow distinct geochemical signature that likely results from the influence of recurrent intense, dense water formation events as well as an unabating bottom trawling activity.

scholarly journals Spatial and temporal variability of water-filled crevasse hydrologic states along the shear margins of Jakobshavn Isbrae, Greenland

2017 ◽  
Author(s):  
Casey A. Joseph ◽  
Derrick J. Lampkin
Keyword(s):  
Temporal Variability ◽  
Large Strain ◽  
Water Injection ◽  
Greenland Ice Sheet ◽  
Spatial And Temporal Variability ◽  
Strain Rates ◽  
Ice Streams ◽  
Lower Elevation ◽  
Melt Water ◽  
The Impact

Abstract. The impact of melt water injection into ice streams over the Greenland Ice Sheet is not well understood. Water-filled crevasses along the shear margins of Jakobshavn Isbræ are known to fill and drain, resulting in weakening of the shear margins due to reduced basal friction. Seasonal variability in the hydrologic dynamics of these features has not been quantified. In this work, we characterize the spatial and temporal variability in the hydrological state (filled or drained) of these water-filled crevasse systems. A fusion of multi-sensor optical satellite imagery was used to examine hydrologic states from 2000 to 2015. The monthly distribution of crevasse systems observed as water filled is unimodal with peak number of filled days during the month of July at 329 days, while May has the least at 15. Over the study period the occurrence of drainage within a given season increases. Inter-seasonal drain frequencies over these systems ranged from 0 to 5. The frequency of multi-drainage events are correlated with warmer seasons and large strain rates. Over the study period, summer temperatures averaged from −1 and 2 °C and tensile strain rates have increased to as high as ~ 1.2 s-1. Intermittent melt water input during hydrofracture drainage responsible for transporting surface water to the bed is largely facilitated by high local tensile stresses. Drainage due to fracture propagation may be increasingly modulated by ocean-induced calving dynamics for the lower elevation ponds. Water-filled crevasses could expand in extent and volume as temperatures increase resulting in regional amplification of ice mass flux into the ice stream system.

scholarly journals ANÁLISE COMPARATIVA DO REGIME HÍDRICO E TÉRMICO DE DOIS SÍTIOS EXPERIMENTAIS NO PAMPA

2016 ◽  
Vol 38 ◽  
pp. 209
Author(s):  
Cláudio Alberto Teichrieb ◽  
Pablo Eli Soares de Oliveira ◽  
Tamires Zimmer ◽  
Cristiano Maboni ◽  
Daniel Michelon dos Santos ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Thermal Conductivity ◽  
Water Content ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Natural Field ◽  
Field Extensions ◽  
Pampa Biome ◽  
The Impact

In the last 15-20 years has greatly increased research on the problem of climate change, necessitating a demand for reliable measurements of absorption and emission of carbon dioxide, methane, as well as the impact on water resources. In the biome Pampa are the largest continuous natural field extensions, requiring a monitoring of water and temperature regime on the ground. The water content of the soil has spatial and temporal variability affecting many hydrological processes and determining this is needed since the soil store and provide the water and nutrients for the plants, thus involving relationships water-soil-plant-atmosphere. In this work, we compared the water content behavior of the soil at depths of 10, 30 and 50 cm, the temperature of the soil at depths of 5, 15 and 30 cm, heat flux in soil installed 10 cm deep and the thermal conductivity was determined in two experimental sites in the Pampa biome, for the period 01.01.2015 to 06.31.2015. It was found that there are differences between the sites in the capacity to retain moisture in the soil and in the ability to store energy in the soil for the study period.

scholarly journals Ergovaline, an endophytic alkaloid. 2. Intake and impact on animal production, with reference to New Zealand

2016 ◽  
Vol 56 (11) ◽  
pp. 1775 ◽  
Author(s):  
A. M. Nicol ◽  
J. L. Klotz
Keyword(s):  
New Zealand ◽  
Daily Intake ◽  
Late Summer ◽  
Animal Production ◽  
Deterrent Effect ◽  
Welfare Implications ◽  
The Mean ◽  
Supplementary Feed ◽  
The Impact ◽  
The Relationship

On the basis of published reports, the daily intake of the alkaloid ergovaline from the consumption of endophyte-containing ryegrass in New Zealand ranges from 0.008 to 0.287 mg ergovaline/kg LW0.75.day. Most of the reports are based on the use of standard endophyte-containing ryegrass and, thus, it is difficult to disassociate the impact of ergovaline consumption from that of lolitrem B. However, physiological effects of ergovaline consumption, such as reduced circulating prolactin concentration, vasoconstriction and elevated core temperature, have been detected at fairly low ergovaline intake, whereas decreased feed intake, liveweight gain and milk production have not generally been observed in animals at an intake below 0.07 mg ergovaline/kg LW0.75.day. Intakes above this value represent only 17% of published values. There are insufficient data to suggest a threshold ergovaline intake associated with heat stress with animal-welfare implications. The relationship between published ergovaline intake and the corresponding ergovaline concentration in pasture is poor (R2 = 0.48), but on average an intake of 0.07 ergovaline/kg LW0.75.day is associated with an ergovaline concentration in ryegrass of 0.70 mg/kg DM. About 16–18% of published ergovaline concentrations in ryegrass pasture exceed this value. The ergovaline concentration in ryegrass is greater in the basal parts of the plant than in the leaf and during the late summer–autumn than in spring. Animals grazing in the lower sward horizons (horizontal grazing plane) are more at risk of high ergovaline intake, although the reduction in grazing intake induced by grazing at low pasture height aids in limiting ergovaline intake. As pasture growth rates decline in late summer, supplementary feed may be used to maintain stocking rate and, if such feeds have zero ergovaline concentration, they serve to dilute the mean dietary ergovaline intake. Ergovaline-containing ryegrass pastures are widely used in New Zealand. It appears that farmers consider the risks of depressed animal production on these pastures to be less than the benefits ergovaline bestows through its deterrent effect of specific insect attack and thus greater survival and pasture persistence.

scholarly journals Variability in glacier albedo and links to annual mass balance for the gardens of Eden and Allah, Southern Alps, New Zealand

2020 ◽  
Vol 14 (10) ◽  
pp. 3425-3448
Author(s):  
Angus J. Dowson ◽  
Pascal Sirguey ◽  
Nicolas J. Cullen
Keyword(s):  
New Zealand ◽  
Mass Balance ◽  
Temporal Variability ◽  
Conservation Status ◽  
Regional Climate ◽  
Southern Alps ◽  
Spatial And Temporal Variability ◽  
Climate Signal ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
High Consistency

Abstract. The gardens of Eden and Allah (GoEA) are two of New Zealand's largest ice fields. However, their remote location and protected conservation status have limited access and complicated monitoring and research efforts. To improve our understanding of the spatial and temporal changes in mass balance of these unique ice fields, observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors are used to monitor annual minimum glacier-wide albedo (α¯yrmin) over the period 2000–2018. The α¯yrmin for 12 individual glaciers ranges between 0.42 and 0.70 and can occur as early as mid-January and as late as the end of April. The evolution of the timing of α¯yrmin indicates a shift to later in the summer over the 19-year period on 10 of the 12 glaciers. However, there is only a weak relationship between the delay in timing and the magnitude of α¯yrmin, which implies that albedo is not necessarily lower if it is delayed. The largest negative departures in α¯yrmin (lower-than-average albedo) are consistent with high snowline altitudes (SLAs) relative to the long-term average as determined from the End of Summer Snowline (EOSS) survey, which has been the benchmark for monitoring glaciers in the Southern Alps for over 40 years. While the record of α¯yrmin for Vertebrae Col 25, an index glacier of the EOSS survey and one of the GoEA glaciers, explains less than half of the variability observed in the corresponding EOSS SLA (R2=0.43, p=0.003), the relationship is stronger when compared to other GoEA glaciers. Angel Glacier has the strongest relationship with EOSS observations at Vertebrae Col 25, accounting for 69 % of its variance (p<0.001). A key advantage in using the α¯yrmin approach is that it enables variability in the response of individual glaciers to be explored, revealing that topographic setting plays a key role in addition to the regional climate signal. The observed variability in individual glacier response at the scale of the GoEA contrasts with the high consistency of responses found by the EOSS record across the Southern Alps and challenges the suggestion that New Zealand glaciers behave as a unified climatic unit. MODIS imagery acquired from the Terra and Aqua platforms also provides insights about the spatial and temporal variability in clouds. The frequency of clouds in pixels west of the Main Divide is as high as 90 % during summer months and reaches a minimum of 35 % in some locations in winter. These complex cloud interactions deserve further attention as they are likely a contributing factor in controlling the spatial and temporal variability in glacier response observed in the GoEA.

scholarly journals Spatial and Temporal Variability of Ice Algal Trophic Markers—With Recommendations about Their Application

2020 ◽  
Vol 8 (9) ◽  
pp. 676
Author(s):  
Eva Leu ◽  
Thomas A. Brown ◽  
Martin Graeve ◽  
Jozef Wiktor ◽  
Clara J. M. Hoppe ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Sea Ice ◽  
Temporal Variability ◽  
Climate Change Impacts ◽  
Isotope Ratios ◽  
Arctic Sea Ice ◽  
Stable Isotope Ratios ◽  
Spatial And Temporal Variability ◽  
Web Studies ◽  
The Impact

Assessing the relative importance of sea ice algal-based production is often vital for studies about climate change impacts on Arctic marine ecosystems. Several types of lipid biomarkers and stable isotope ratios are widely used for tracing sea ic-associated (sympagic) vs. pelagic particulate organic matter (POM) in marine food webs. However, there has been limited understanding about the plasticity of these compounds in space and time, which constrains the robustness of some of those approaches. Furthermore, some of the markers are compromised by not being unambiguously specific for sea ice algae, whereas others might only be produced by a small sub-group of species. We analyzed fatty acids, highly branched isoprenoids (HBIs), stable isotope ratios of particulate organic carbon (POC) (δ13C), as well as δ13C of selected fatty acid markers during an Arctic sea ice algal bloom, focusing on spatial and temporal variability. We found remarkable differences between these approaches and show that inferences about bloom characteristics might even be contradictory between markers. The impact of environmental factors as causes of this considerable variability is highlighted and explained. We emphasize that awareness and, in some cases, caution is required when using lipid and stable isotope markers as tracers in food web studies and offer recommendations for the proper application of these valuable approaches.

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