The influence of weather on the quality of tropical legume pasture during the dry season in Northern Australia. II. Moulding of standing hay in relation to rain and dew

1981 ◽  
Vol 32 (4) ◽  
pp. 589 ◽  
Author(s):  
RL McCown ◽  
BH Wall
Keyword(s):  
Relative Humidity ◽  
Leaf Litter ◽  
Bulk Sample ◽  
Dry Season ◽  
Northern Australia ◽  
Mould Growth ◽  
Tropical Legume ◽  
Dry Tropics

Naturally desiccated legume pasture is valuable forage in the dry season but is very vulnerable to moulding, which drastically reduces its acceptability to cattle. At a network of sites in the wet-dry tropics of Australia, trends in mouldiness of standard leaf 'litter' samples were monitored in relation to rain, dew, and rates of drying. Although heavy dews occurred frequently at some sites, only the immediate top layer of fallen leaf moulded. This had a very small effect on the mouldiness of the bulk sample. Appreciable moulding occurred only after at least 2 mm rain, but in some cases there was no mould growth after over 10 mm rain; the amount of rain accounted for only 23 % of the variation in mouldiness. The duration of wetness of the leaf litter, as indicated by the duration of 95 % relative humidity 10 cm above the ground after rain, accounted for 91 % of the variation in mouldiness. At the more humid sites, material which was exposed for several weeks before rain moulded more rapidly after rain than did recently exposed material, even though at the time of rain there were no visible differences. Differences in causation of moulding of conventional hay and of 'standing hay' are discussed.

The influence of weather on the quality of tropical legume pasture during the dry season in northern Australia. III. Effects of digestibility and chemical composition

1989 ◽  
Vol 40 (3) ◽  
pp. 573 ◽  
Author(s):  
RL McCown ◽  
BH Wall
Keyword(s):  
Dry Matter ◽  
Mediterranean Climate ◽  
Dry Season ◽  
In Vitro Digestibility ◽  
Northern Australia ◽  
Pasture Legumes ◽  
Dry Matter Digestibility ◽  
Dry Tropics

In the semi-arid tropics, accumulated shed leaf of certain pasture legumes can provide highly nutritious feed for cattle in the dry season. Previous papers in this series have dealt with the fungal spoilage of leaf of Caribbean stylo in response to dew and unseasonal rainfall and the threat to acceptability by cattle. This paper focuses on the effects of varying degrees of moulding and leaching on dry matter digestibility of leaf of this legume. Uniform leaf material of high digestibility was exposed at six locations during the dry season and samples retrieved at 4-weekly intervals. From initial values of 75%. in vitro digestibility dropped to as low as 50%. Degree of moulding, as indicated by a quantitative index of discoloration, accounted for about 80�/o of loss. Moulding was much more important than leaching. This latter finding in the winter-dry tropics contrasts with previous findings in the summer-dry Mediterranean climate.

The influence of weather on the quality of tropical legume pasture during the dry season in Northern Australia. I. Trends in sward structure and moulding of standing hay at three locations

1981 ◽  
Vol 32 (4) ◽  
pp. 575 ◽  
Author(s):  
RL McCown ◽  
BH Wall ◽  
PG Harrison
Keyword(s):  
Leaf Litter ◽  
Nutritive Value ◽  
Environmental Control ◽  
Dry Season ◽  
Weather Data ◽  
Northern Australia ◽  
Seasonally Dry ◽  
Actual Contribution ◽  
Tropical Climates

In seasonally dry tropical climates, animal production is severely constrained during the dry season by the low nutritive value of dry grass forage. Introduction of a legume such as Caribbean stylo can provide a valuable alternative forage during this period, mainly in the form of leaf litter and accompanying seed. The actual contribution of dry legume is closely dependent on its moisture regimen, which determines the degree of mould growth, an important palatability factor. This paper reports a 2-year study conducted at Katherine, Darwin and Townsville of the environmental control of both the timing and rate of leaf shed and of the subsequent moulding of leaf litter. At Katherine and Darwin, leaf was shed early and rapidly; at Townsville, much lower evaporation rates and small rainfalls delayed and prolonged leaf shed by several weeks. The data provide a model for predicting leaf shed by using standard weather data to aid the assessment of the risk of forage damage by precipitation.

Seasonal diet preferences of chital deer in the northern Queensland dry tropics, Australia

2020 ◽  
Vol 42 (3) ◽  
pp. 211
Author(s):  
Kurt Watter ◽  
Greg Baxter ◽  
Michael Brennan ◽  
Tony Pople ◽  
Peter Murray
Keyword(s):  
Dry Season ◽  
Wet Season ◽  
Variable Environment ◽  
Dry Tropics ◽  
Plant Groups ◽  
Axis Axis ◽  
Plant Group ◽  
Diet Preference ◽  
Dry Seasons

Chital deer (Axis axis) were introduced to the Burdekin dry tropics of north Queensland, Australia, in the late 1800s. Here rainfall and plant growth are highly seasonal and a nutritional bottleneck for grazing animals occurs annually before the wet season. This study describes the seasonal changes in diet and diet preference of chital in this seasonally-variable environment. Rumen samples were taken from 162 deer from two sites over the wet and dry seasons of two consecutive years and sorted macroscopically for identification. Relative seasonal availability of plant groups was estimated using step point sampling of areas grazed by chital. Chital alter their diet seasonally according to availability and plant phenology. Chital utilised 42 plant genera including grasses, forbs, subshrubs, shrubs, trees and litter. Grass consumption ranged from 53% of biomass intake during the dry season to 95% during the wet season. The predominance of grass in the wet season diet exceeded relative availability, indicating a strong preference. Although grass contributed more than half of the dry season diet it was the least preferred plant group, given availability, and the least actively growing. Shrubs were the preferred plant type in the dry season, and least subject to seasonal senescence. Composition and quantity of seasonal pastures vary markedly in north Queensland, and chital alter their diet by consuming those plants most actively growing. The increased dry season intake of non-grass forage appears to be a strategy to limit the detriment resulting from the progressive deterioration in the quality of grass.

Ground Surface Features Attributable to Feral Buffalo, Bubalus bubalis I. Their Distribution relative to Vegetation Structure and Plant Lifeform

1984 ◽  
Vol 11 (2) ◽  
pp. 303 ◽  
Author(s):  
JA Taylor ◽  
GR Friend
Keyword(s):  
Leaf Litter ◽  
Vegetation Structure ◽  
Ground Surface ◽  
Bubalus Bubalis ◽  
Dry Season ◽  
Northern Australia ◽  
Wet Season ◽  
Surface Features ◽  
Dense Vegetation ◽  
Lower Elevation

Relationships among ground surface features attributable to feral buffalo (viz. wallows, trails, pug marks and dung pats), vegetation structure, and lifeform spectrum were examined in both dry and wet seasons in a tropical monsoonal area of northern Australia. In the dry season, the frequency of pug marks was negatively correlated with the number of trails and dung pats, and positively correlated with the number of wallows. In the wet season only dung pats and wallows were significantly correlated. In the dry season, wallows were not associated with any vegetation structure or lifeform attribute, but in the wet season they were associated with dense foliage <1 m high. Trails occurred in areas of low dense vegetation (<0.5 m) in the dry season, but in the wet were uncommon and positively associated with lianas. Pug marks occurred mainly in the lower-elevation, treeless areas dominated by forbs. Whereas the nature and strength of the relationships of pug marks to plant lifeform or vegetation structure remained constant from season to season, those involving dung pats changed seasonally. In the dry season, dung pats were associated with the higher-elevation areas where trees, lianas, dense mid-level foliage (1.5-2.5 m) and leaf-litter were common. In the wet, they were associated with low vegetation (<1 m) dominated by forbs, and were negatively correlated with the factors important in the dry.

The effect of a phosphorus supplement on the performance of steers grazing Townsville stylo-based pasture in north Queensland

1977 ◽  
Vol 17 (86) ◽  
pp. 357 ◽  
Author(s):  
L Winks ◽  
FC Lamberth ◽  
PK O'Rourke
Keyword(s):  
Dry Season ◽  
Wet Season ◽  
Dry Tropics ◽  
Stylosanthes Humilis ◽  
Native Pasture ◽  
Weight Gains ◽  
Annual Grasses ◽  
Townsville Stylo

The effect of phosphorus supplementation on the performance of steeres grazing unfertilized native pasture and Townsville stylo (Stylosanthes humilis) with andwithout superphosphate fertilizer on the subcoastal spear grass region of the dry tropics of north Queensland was studied over a period of 40 months. Liveweight gains in the absence of supplementation on fertilized Townsville stylo pastures were greater than on unfertilized Townsville stylo, where performance was similar to that recorded on untreated native pasture. Phosphorus supplementation increased weight gains during the wet season on both unfertilized Townsville stylo and native pasture but had no significant effect on dry season performance or performance on fertilized Townsville stylo. Fertilized areas became dominated by annual grasses, Digitaria ciliaris and Brachiaria milliiformis, and legume yields were higher on unfertilized than on fertilized areas. Fertilizer improved the quality of available pastures.

The influence of weather on the quality of tropical legume pasture during the dry season in northern Australia. IV. Geographic variation in risk of spoilage of standing hay

1989 ◽  
Vol 40 (3) ◽  
pp. 579 ◽  
Author(s):  
BH Wall ◽  
RL McCown
Keyword(s):  
Geographic Variation ◽  
Dry Season ◽  
Soil Water Storage ◽  
Northern Australia ◽  
Considerable Time ◽  
Nutritional Strategy ◽  
Leaf Shedding ◽  
Dry Seasons ◽  
Rate Of Evaporation

This paper assesses the geographic variation in northern Australia of the risk of deterioration to the point of 'spoilage', including both the beneficial and the deleterious effects of rain. The procedure is a modified water balance in which leaf shedding is driven by decline in soil water storage, and moulding is governed by the rate of evaporation following a rainfall of 2 mm or more.For 28 stations, from the West Kimberley to Central Queensland, an average of 40 dry seasons have been analysed for the periods when the legume would have been green, dry but unspoilt, and spoilt. A 'dry leaf' nutritional strategy is feasible where the dry seasons are reliably rainless. Even in regions with a high risk of rain, if green leaf is maintained for a considerable time in the dry season there is also a low risk of spoilage, and the use of non-deciduous legume species in these regions and elsewhere is discussed.

Resource partitioning among five sympatric species of freshwater turtles from the wet–dry tropics of northern Australia

2017 ◽  
Vol 44 (3) ◽  
pp. 219 ◽  
Author(s):  
Michael A. Welsh ◽  
J. Sean Doody ◽  
Arthur Georges
Keyword(s):  
Resource Partitioning ◽  
Niche Overlap ◽  
Sympatric Species ◽  
Dry Season ◽  
Gut Contents ◽  
Microhabitat Use ◽  
Freshwater Turtles ◽  
Northern Australia ◽  
Dietary Shift ◽  
Dry Tropics

Context Resource partitioning of diet and microhabitat was examined for five sympatric species of freshwater turtles in the Daly River in the northern end of Northern Territory (Top End) in Australia. The Daly River supports a high diversity of freshwater turtles, making it the ideal place to study a freshwater turtle community. Aims To determine the dry-season diet and microhabitat use of Carettochelys insculpta, Elseya dentata, Chelodina oblonga, Emydura victoriae and Emydura subglobosa worrelli and examine intraspecific and interspecific niche overlap and ontogenetic dietary shift. Methods Gut contents were collected by stomach flushing, and microhabitat use was determined by recording where each turtle was first seen before capture. Diet and microhabitat use were compared using an index of relative importance. Niche overlap was measured with Horn’s overlap index. Key results Carettochelys insculpta is an opportunistic omnivore that feeds mostly on ribbonweed (Vallisneria spiralis) and aquatic snails. Elseya dentata is herbivorous, feeding primarily on aquatic algae. The diets of C. insculpta and E. dentata overlapped moderately, but the overall niche overlap was low because they occupied different microhabitats within the river. Chelodina oblonga fed very little, and may use the Daly River as a dry-season refuge. Emydura victoriae is molluscivorous, consuming more molluscs as it grows. This ontogenetic dietary shift was associated with megacephaly (extreme broadly expanded head that is too large to fit into the carapace) and expanded triturating surfaces. This specialisation allows adult E. victoriae to feed exclusively on molluscs and so their diet overlapped little with other species. Emydura subglobosa worrelli was omnivorous, consuming mostly freshwater sponge and apparently preferring more lentic water. Conclusions The freshwater turtles of the wet–dry tropics are usually reported as being heavily reliant on the seeds, fruits and leaves of riparian vegetation; however, the present study showed that the dry-season diet in perennial rivers is primarily of aquatic origin. Implications The study suggested that populations of C. insculpta, E. dentata and E. victoriae could be threatened by broad-scale development in northern Australia if there were substantive impacts on aquatic macrophytes and molluscs in the Daly River system.

Reproductive seasonality in the tropical butterfly Hypolimnas bolina (Lepidoptera: Nymphalidae) in northern Australia

2001 ◽  
Vol 17 (4) ◽  
pp. 483-494 ◽  
Author(s):  
DARRELL J. KEMP
Keyword(s):  
Reproductive Activity ◽  
Dry Season ◽  
Northern Australia ◽  
Breeding Phenology ◽  
Reproductive Seasonality ◽  
Leaf Quality ◽  
Tropical Environments ◽  
Dry Tropics ◽  
Nymphalid Butterfly ◽  
The Tropics

Because seasonality in tropical environments is driven by variation in rainfall, phytophagous tropical organisms are expected to exhibit mechanisms of escape in space and time that allow them to synchronize their breeding efforts with suitably wet periods of the year. This hypothesis was addressed by studying the breeding phenology of the nymphalid butterfly Hypolimnas bolina (L.) in the Australian wet-dry tropics. This species favours small, herbaceous larval foodplants that either die off annually or exhibit marked declines in leaf quality during the dry season. As expected, reproductive activity in H. bolina was broadly correlated with both rainfall and humidity, with individuals spending part of the dry season (early April to late August) sheltering in overwintering sites in a state of reproductive diapause. The timing of the overwintering period was similar between the 2 years, which suggests that individuals respond to seasonally predictable cues such as photoperiod. At least in 1998, the exit of butterflies from overwintering sites was relatively sudden and coincided with the first spring rainfall event. These findings suggest that H. bolina copes with seasonal adversity in the tropics by means of a regularly timed diapause.

A comparison of hygrothermal simulation results derived from four simulation tools

2021 ◽  
pp. 174425912098876
Author(s):  
Maurice Defo ◽  
Michael Lacasse ◽  
Abdelaziz Laouadi
Keyword(s):  
Relative Humidity ◽  
Outer Layer ◽  
Growth Index ◽  
Mould Growth ◽  
Simulation Tools ◽  
Assembly Design ◽  
Hygrothermal Simulation ◽  
Moisture Performance ◽  
Wood Frame ◽  
Wall Assembly

The objective of this work was to compare the hygrothermal responses and the moisture performance of four wood-frame walls as predicted by four hygrothermal (HAM) simulation tools, namely: DELPHIN, WUFI, hygIRC and COMSOL. The four wall systems differ only in their cladding type; these were fibreboard, vinyl, stucco and brick. Three Canadian cities having different climates were selected for simulations: Ottawa, Ontario; Vancouver, British Columbia and Calgary, Alberta. In each city, simulations were run for 2 years. Temperature and relative humidity of the outer layer of OSB sheathing were compared amongst the four simulation tools. The mould growth index on the outer layer of the OSB sheathing was used to compare the moisture performance predicted by the respective hygrothermal simulation tools. Temperature profiles of the outer layer of the OSB sheathing were all in good agreement for the four HAM tools in the three locations. For relative humidity, the highest discrepancies amongst the four tools were found with stucco cladding where differences as high as 20% could be found from time to time. Mould growth indices predicted by the four HAM tools were similar in some cases but different in other cases. The discrepancies amongst the different HAM tools were likely related to: the material property processing, how the quantity of wind-driven rain absorbed at the cladding surface is computed and some implementation details. Despite these discrepancies, The tools generally yielded consistent results and could be used for comparing the impacts of different designs on the risk of premature deterioration, as well as for evaluating the relative effects of climate change on a given wall assembly design.

The use of regional and alluvial groundwater by riparian trees in the wet‐dry tropics of northern Australia.

2021 ◽  
Author(s):  
Caroline A. Canham ◽  
Clément Duvert ◽  
Leah S. Beesley ◽  
Michael M. Douglas ◽  
Samantha A. Setterfield ◽  
...  
Keyword(s):  
Northern Australia ◽  
Dry Tropics ◽  
Riparian Trees ◽  
Alluvial Groundwater
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