Soil seed densities and emergence patterns in pastures in the seasonally dry tropics of northeastern Australia

1991 ◽  
Vol 16 (2) ◽  
pp. 159-169 ◽  
Author(s):  
JOHN G. McIVOR ◽  
CHRISTOPHER J. GARDENER
Keyword(s):  
Seasonally Dry ◽  
Dry Tropics ◽  
Emergence Patterns

Acacia crassicarpa (northern wattle).

2021 ◽  
Author(s):  
Nick Pasieczni ◽  
Duncan McDonald
Keyword(s):  
Imperata Cylindrica ◽  
Low Fertility ◽  
Soil Types ◽  
Weed Species ◽  
Root Nodulation ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Acacia Crassicarpa ◽  
Round Timber ◽  
Pulp Production

Abstract A. crassicarpa is one of the fastest-growing acacias for planting on degraded sites in the seasonally-dry tropics. It tolerates a range of soil types, particularly those of low fertility. It is a nitrogen-fixing tree that produces abundant natural root nodulation. It is fire resistant and competes favourably against weed species such as Imperata cylindrica. It has the potential to produce a dense hardwood that can be used in industrial pulp production, as sawn or round timber for construction or as fuelwood.

Diet selection by cattle grazing Stylosanthes-grass pastures in the seasonally dry tropics: effect of year, season, stylo species and botanical composition

1996 ◽  
Vol 36 (7) ◽  
pp. 781 ◽  
Author(s):  
DB Coates
Keyword(s):  
Cattle Grazing ◽  
Diet Selection ◽  
Dry Season ◽  
Major Influence ◽  
Botanical Composition ◽  
Wet Season ◽  
Seasonally Dry ◽  
Dietary Preference ◽  
Dry Tropics ◽  
Opportunity For Selection

The dietary preference of cattle grazing Stylosanthes-based pastures in the seasonally dry tropics of North Queensland was studied using faecal carbon ratios (S13C) to determine grass-legume proportions. Estimates were made at monthly intervals for several years in 1 experiment to determine the effect of year, season and botanical composition on dietary stylo proportions. In another experiment, the effect of stylo cultivars (Verano and Seca) on dietary preference was monitored for 17 months. Where pastures provided ample opportunity for selection, cattle showed a strong preference for grass in the early wet season and in the late dry season. The proportion of stylo in the diet increased during the wet season and reached peak proportions (as high as 80%) in the late wet season or early dry season. Dietary stylo proportions decreased as pastures dried off and as the stylo shed leaf or became more stemmy. The length of the wet season and the amount and distribution of rainfall had a major influence on the seasonal pattern of diet selection. Stylo rarely fell below 20% in the diet. On an annual basis, stylo accounted for about 45% of the diet which was appreciably higher than the proportion of stylo in the pasture. Dietary stylo proportions were higher on Seca-based pasture than on Verano-based pasture. The avoidance of stylo in the early wet season was less pronounced with Seca compared with Verano. Later in the season Seca was the dominant dietary component for a much longer period than Verano. The effect of botanical composition on dietary grass-legume proportions varied between and within years. Correlations between grass-legume proportions in the pasture and in the diet were highest in the late dry season and early wet season when preference for grass was strongest. At the end of the wet season when cattle preferred stylo, dietary stylo was not related to pasture stylo content except in a drought year. Averaged over the full year, dietary stylo content was significantly correlated with pasture stylo content in all years and the correlation was highest in a drought year when there was a high level of utilisation and less opportunity for selection. A simple model relating dietary stylo to pasture stylo was developed and is discussed.

The assessment of seasonal yield using some Stylosanthes guyanensis accessions in humid tropical and sub-tropical environments

1977 ◽  
Vol 17 (86) ◽  
pp. 425 ◽  
Author(s):  
LA Edye ◽  
WT Williams ◽  
RL Burt ◽  
B Grof ◽  
SL Stillman ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
Growth Period ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Growth Patterns ◽  
Seasonal Growth ◽  
Seasonally Dry ◽  
Tropical Environments ◽  
Dry Tropics

The seasonal growth patterns of some S. guyanensis accessions were compared in three humid environments at South Johnstone (extended rainfall tropics), 'Heathlands' (seasonally dry tropics) and Cooroy (humid sub-tropics). The accessions were selected mainly for their productivity in previously described small mown sward experiments over three years at each site. Previous methods of presenting seasonal growth patterns are reviewed, and a new, simpler method of presentation is defined. Growth was highly seasonal at all sites. There was no growth during July to November at 'Heathlands' and Cooroy due to moisture and temperature limitations respectively. At South Johnstone growth was continuous but depressed in August and December with limitations due to both soil moisture and temperature: the maximum growth rate was 22 times the minimum growth rate. The accessions differed markedly in their growth patterns at each site. In general, the yield differences between accessions were greater at the beginning and end of the growing season than during the peak growth period. The highest yielding accessions at each site had high growth rates spread over a long period. The yield distribution and persistence of Q8231 and 46589C seemed superior to existing cultivars in tropical and sub-tropical environments respectively

The annual variation in yield of pastures in the seasonally dry tropics of Queensland

1974 ◽  
Vol 14 (68) ◽  
pp. 328 ◽  
Author(s):  
RL McCown ◽  
P Gillard ◽  
LA Edye
Keyword(s):  
Water Balance ◽  
Dry Matter ◽  
Annual Variation ◽  
Water Balance Model ◽  
Actual Evapotranspiration ◽  
Balance Model ◽  
Dry Matter Yield ◽  
Seasonally Dry ◽  
Dry Tropics

Dry matter yield of three vegetation-fertilizer combinations was found to be closely related to actual evapotranspiration estimated using simple water balance model. Cumulative actual evapotranspiration was estimated for each of 69 years of rainfall records and a description of annual variation in yields obtained using yield/actual evapotranspiration regressions.

Soil respiration in the seasonally dry tropics near Townsville, North-Queensland

Soil Research ◽  
1990 ◽  
Vol 28 (5) ◽  
pp. 737 ◽  
Author(s):  
JA Holt ◽  
MJ Hodgen ◽  
D Lamb
Keyword(s):  
Soil Respiration ◽  
Root Respiration ◽  
Respiratory Activity ◽  
Major Effect ◽  
Wet Season ◽  
Untreated Soil ◽  
Seasonally Dry ◽  
Respiration Rates ◽  
Dry Tropics ◽  
Total Soil Respiration

The contribution of root respiration to total soil respiration has been examined in an Australian tropical semi-arid woodland. Respiration rates were estimated by measuring CO2 released from untreated soil and from soil where roots had been severed and were extensively decomposed. The amount of C released as CO2 by soil respiration was estimated to be 3800 kg ha-1 year-1, and by root respiration to be 1500 kg C ha-l year-1. Soil moisture was found to have a major effect on soil respiration, with temperature being less significant. Consequently, most respiratory activity in the soil was confined to the relatively short wet season, with respiration rates being much lower during the dry season.

Sustainability of holistic and conventional cattle ranching in the seasonally dry tropics of Chiapas, Mexico

2013 ◽  
Vol 120 ◽  
pp. 38-48 ◽  
Author(s):  
Bruce G. Ferguson ◽  
Stewart A.W. Diemont ◽  
Rigoberto Alfaro-Arguello ◽  
Jay F. Martin ◽  
José Nahed-Toral ◽  
...  
Keyword(s):  
Cattle Ranching ◽  
Seasonally Dry ◽  
Dry Tropics

Limited impact of irrigation on the phenology of Brachychiton megaphyllus: a deciduous shrub that flowers while leafless during the tropical dry season

2015 ◽  
Vol 31 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Patricia J. Bate ◽  
Donald C. Franklin
Keyword(s):  
Soil Moisture ◽  
Reproductive Activity ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Wet Season ◽  
Canopy Development ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Tap Root ◽  
Leaf Flush

Abstract:A suite of woody plants inhabiting the seasonally dry tropics flower while leafless during the dry season, raising intriguing questions about the role of moisture limitation in shaping their phenology. Brachychiton megaphyllus is one such species, a shrub of open forests and savannas in northern Australia. We documented leaf and reproductive phenology of 14 shrubs, and irrigated a further 15, to determine if soil moisture affected leafiness and reproductive activity. Brachychiton megaphyllus showed first flower buds shortly after the cessation of wet-season rains, and budded and flowered throughout the dry season. In some plants, leaf flush occurred prior to the first rains. Rates of fruit set and maturity were very low. Irrigation did not significantly influence leaf shoot or subsequent canopy development. Contrary to expectation, irrigation decreased the production of buds and flowers though it had no impact on the production of fruit, a response for which we suggest a number of hypotheses. Phenological responses to irrigation may have been limited because B. megaphyllus responds primarily to cues other than soil moisture and is buffered against seasonal drought by a large tap root. This suggests mechanisms by which flowering while leafless may occur in a range of species.

Australian Rock-Mammals: A Phenomenon of the Seasonally Dry Tropics

Biotropica ◽  
1988 ◽  
Vol 20 (1) ◽  
pp. 70 ◽  
Author(s):  
W. J. Freeland ◽  
J. W. Winter ◽  
S. Raskin
Keyword(s):  
Seasonally Dry ◽  
Dry Tropics

Diet composition of cattle grazing Stylosanthes - grass pastures in the seasonally dry tropics: the effect of phosphorus as fertiliser or supplement

1998 ◽  
Vol 38 (1) ◽  
pp. 7 ◽  
Author(s):  
D. B. Coates ◽  
R. P. Le Feuvre
Keyword(s):  
Diet Composition ◽  
Isotope Analysis ◽  
Cattle Grazing ◽  
Diet Selection ◽  
Wet Season ◽  
Seasonally Dry ◽  
Stylosanthes Hamata ◽  
Dry Tropics ◽  
Extractable P ◽  
Induced Changes

Summary. The effect of phosphorus (P) on diet selection in cattle grazing pastures based on Stylosanthes hamata cv. Verano andS. scabra cv. Seca in the seasonally dry tropics was studied in 3 grazing trials on soils with inherently low P status ( 5 µg/g bicarbonate-extractable P). The contribution of Stylosanthes (stylo) to diets was estimated at regular intervals (approximately monthly) using carbon isotope analysis of faeces. Feeding P supplement increased the proportion of stylo in the diet but the effect was seasonal and variable, being most pronounced during the late wet and early dry seasons when dietary stylo proportions are usually highest. The results indicated that P supplement influenced diet selection through its effect on dietary P status such that cattle with a deficiency of dietary P select a lower proportion of stylo than those with higher P intakes. The effect of fertiliser P on dietary stylo content was also variable. The dominant effect was via fertiliser-induced changes in pasture botanical composition. Higher stylo proportions in the diet of heifers grazing unfertilised pasture compared with those grazing fertilised pasture were associated with increasing stylo dominance in unfertilised pastures as opposed to grass dominance in fertilised pastures. At the same time there was evidence of a fertiliser treatment effect that was consistent with dietary P status influencing diet composition. In the grass-dominant pastures, unsupplemented cattle on low P pasture selected less stylo than those grazing pastures of higher P status due to more frequent fertilising but there was no difference where P supplement was fed. A strong seasonal preference for grass early in the wet season, reinforced by a generally reduced preference for stylo in cattle with diets deficient in P, probably hastened the development of stylo dominance in unfertilised pasture where P supplement was not fed.

Sign in / Sign up

Export Citation Format

Share Document