Possible effects of removal of Mulga on rangeland stability in South Western Queensland.

1976 ◽  
Vol 1 (1) ◽  
pp. 24 ◽  
Author(s):  
AJ Pressland
Keyword(s):  
Basal Area ◽  
Rangeland Management ◽  
Property Management ◽  
Nutrient Losses ◽  
Livestock Management ◽  
Run Off ◽  
Acacia Aneura ◽  
Complete Clearing

Thinning or complete clearing of dense mulga (Acacia aneura) woodlands in south western Queensland may lead to undesirable rangeland conditions unless sound property management is practised. Even ten years after thinning, ground storey vegetation in an ungrazed situation is still in a state of flux. Livestock management following clearing can markedly influence pasture composition and mulga regeneration. Poor rangeland management may lead to reductions in pasture basal area sufficient to reduce productivity and accelerate degeneration through soil and nutrient losses in run-off waters.

scholarly journals Rangeland Management Series: Livestock Management During Drought

2001 ◽  
Author(s):  
Neil K McDougald ◽  
William E Frost ◽  
Ralph L Phillips
Keyword(s):  
Rangeland Management ◽  
Livestock Management

LOSSES OF ORGANIC MATTER AND NUTRIENTS BY WATER EROSION IN CASSAVA-BASED CROPPING SYSTEMS

1997 ◽  
Vol 33 (4) ◽  
pp. 487-498 ◽  
Author(s):  
M. RUPPENTHAL ◽  
D. E. LEIHNER ◽  
N. STEINMÜLLER ◽  
M. A. EL SHARKAWY
Keyword(s):  
Organic Matter ◽  
Cropping Systems ◽  
Water Erosion ◽  
Nutrient Losses ◽  
Runoff Water ◽  
Natural Rainfall ◽  
Run Off ◽  
Exchangeable Magnesium ◽  
Runoff Control ◽  
Phosphorus Runoff

Erosion trials under natural rainfall were conducted at two locations in the Andean hillsides of south-west Colombia on moderate slopes. Sediment-bound losses of seven cassava (Manihot esculenta) cropping systems per cropping period ranged from 26 to 1726 kg ha−1 for organic matter, 0.9 to 65.5 kg ha−1 for total nitrogen, 0.03 to 2.1 kg ha−1 for exchangeable magnesium, 0.04 to 2.8 kg ha−1 forexchangeable potassium and 0.004 to 0.8 kg ha−1 for Bray-II phosphorus. Runoff water contributed substantially to total available potassium, magnesium and phosphorus losses. Concentrations of soluble phosphorus in runoff water from heavily eroded continuously clean-tilled fallow plots were slightly higher than from cropped and fertilized plots. Enrichment ratios for sediments from these highly aggregated Inceptisols were low. Sand-sized particles were selectively removed by water erosion. The higher proportion of nutrient losses with run-off water in our study stressed the importance of runoff control along with attempts to control soil losses and thus diminish both nutrient losses and surface water eutrophication.

Inability of fire to control vegetation dynamics in low-productivity mulga (Acacia aneura)-dominated communities of eastern Australia

2017 ◽  
Vol 26 (10) ◽  
pp. 896 ◽  
Author(s):  
J. L. Silcock ◽  
J. Drimer ◽  
J. Fraser ◽  
R. J. Fensham
Keyword(s):  
Vegetation Structure ◽  
Seedling Recruitment ◽  
Fire Severity ◽  
Basal Area ◽  
Fire Frequency ◽  
Historical Record ◽  
Livestock Grazing ◽  
Eastern Australia ◽  
Australian Continent ◽  
Acacia Aneura

Reduced fire frequency and severity associated with livestock grazing are cited as a cause of woody plant encroachment and thickening in rangelands, but such paradigms are difficult to test experimentally owing to limited opportunities to burn. Mulga (Acacia aneura) dominates 25% of the Australian continent and epitomises this quandary. We measured the effect of rare wildfires on tree and shrub mortality and subsequent regeneration in mulga-dominated communities to critically examine prevailing but unsubstantiated paradigms of vegetation structural change. Mortality of mature mulga trees was positively correlated with fire severity, which was negatively correlated with tree basal area per hectare. High-severity fires killed the majority of mulga, but only occurred in more open areas, whereas low-severity fires typical of many mulga communities did not kill substantial proportions of mature mulga. The majority of mulga saplings were killed across all sites regardless of fire severity. Seedling germination was stimulated by fire, but not dependent on it. Green turkey bush (Eremophila gilesii) was the only shrub species with >50% mortality across all sites. Combined with the rarity of fire events in the historical record, our results, particularly limited fire mortality and enhanced post-fire seedling recruitment, suggest that the role of fire in shaping vegetation structure in mulga-dominated communities has been overstated. The decoupling of fire and vegetation structure is consistent with emerging regional studies in low-productivity semiarid environments.

Herbage Production Following Rainfall Redistribution in a Semi-Arid Mulga (Acacia Aneura) Woodland in Western New South Wales.

1998 ◽  
Vol 20 (2) ◽  
pp. 206 ◽  
Author(s):  
JC Noble ◽  
RSB Greene ◽  
WJ Muller
Keyword(s):  
Soil Water ◽  
New South ◽  
Water Storage ◽  
Rainfall Event ◽  
Soil Water Storage ◽  
Stocking Rate ◽  
South Wales ◽  
Run Off ◽  
Acacia Aneura ◽  
Semi Arid

The effects of stocking rate (nominally ranging from 0.3 up to 0.8 dry sheep equivalents per ha) on rainfall redistribution, soil-water storage and herbage production were studied in three contiguous geomorphic zones (run-off, interception and run-on zones) in a semi-arid mulga (Acacia aneura) woodland in western New South Wales. The amount of rainfall redistribution increased directly with rainfall but there was no significant effect of stocking rate on the amount of soil-water stored in various zones. while soil-water storage differed little between zones following a minor rainfall event (11.9 mm), it was significantly higher (P < 0.001) in the run-on zone following a major rainfall event (42.7 mm). The interception zone was by far the most productive herbage zone contributing a significantly (P < 0.01) disproportionate amount of forage (c. 90% of total paddock production at low stocking rates) despite this zone only occupying a relatively small proportion (c. 12%) of landscape catenae. Herbage in the interception zone principally comprised palatable C3 perennial grasses such as Thyridolepis mitchelliana (mulga grass) and Monachather paradoxa (bandicoot grass). Experimental manipulation confirmed the fundamental importance of rainfall redistribution as a landscape process mediating herbage production in these semi-arid plant communities. Dry matter production by Eragrostis eriopoda (woollybutt) was significantly enhanced (P < 0.05) in the run-off zone when incident rainfall was retained in situ by metal barriers. Conversely, production by Thyridolepis mitchelliana in the lower interception zone was significantly depressed (P < 0.01) where similar barriers prevented access by overland flow. The results are discussed in the context of developing conservative management strategies designed to maintain effective landscape processes in these extensive ecosystems.

Land Condition in the Tropical Tallgrass Pasture Lands. 1. Effects on Herbage Production.

1995 ◽  
Vol 17 (1) ◽  
pp. 69 ◽  
Author(s):  
John G. Mcivor ◽  
Andrew J. Ash ◽  
Garry D. Cook
Keyword(s):  
Basal Area ◽  
Nutrient Status ◽  
Condition Index ◽  
Perennial Grasses ◽  
Individual Species ◽  
Growing Seasons ◽  
North East ◽  
Linear Relationships ◽  
Run Off ◽  
Land Condition

A quantitative condition index based on vegetation (botanical composition and basal area of perennial grasses) and soil characteristics (erodibility, nutrient status and availability, partitioning of rainfall into infiltration and run-off) was developed for tropical tallgrass pastures near Charters Towers (north-east Queensland) and Katherine (Northern Territory). Herbage growth and the responses of individual species at 10 sites over two growing seasons were related to the index. At all sites there were significant linear relationships between herbage growth and condition index although the values differed between sites. Annual grasses increased and most perennial grasses decreased as condition declined but Bothriochloa pertusa and Bothriochloa ewartiana were most abundant at intermediate condition levels. The response of Chrysopogon fallax varied widely between sites. The lower herbage production on poor condition sites will result in lower carrying capacity.

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