Soil Moisture Redistribution as Affected by Throughfall and Stemflow in an Arid Zone Shrub Community

1976 ◽  
Vol 24 (5) ◽  
pp. 641 ◽  
Author(s):  
AJ Pressland
Keyword(s):  
Soil Moisture ◽  
Arid Zone ◽  
Tree Density ◽  
Ground Flora ◽  
Infiltration Rates ◽  
Close Proximity ◽  
Stem Flow ◽  
Survival And Growth ◽  
Ecological Importance ◽  
Acacia Aneura

Changes in soil moisture under various densities of mulga (Acacia aneura F. Muell.) were followed from December 1971 to October 1973. Stemflow was instrumental in storing water at depth in the soil, being particularly noticeable with medium falls of rain (~ 75 mm); heavy (~ 160 mm) falls tended to mask the effect. Throughfall increased linearly with aggregate rainfall, and percentage throughfall decreased with increasing tree density. Of incoming precipitation, 94% was partitioned as throughfall under a tree density of 40 trees/ha-1 compared with 86% at a density of 4000 trees/ha. No distinct soil moisture patterns due to throughfall were found. Infiltration rates of water into the soil decreased with increasing distance from trees, being 46, 22 and 17 mm/h-1 after 10 min at distances 0.25, 0.5 and 2 m from a tree bole respectively, thus demonstrating that stemflow waters are absorbed at close proximity to the tree bole.The results are discussed in terms of the ecological importance of stem flow and soil moisture patterning to the survival and growth of mulga and associated ground flora.

Effect of Stand Density on Water Use of Mulga (Acacia aneura F.muell.) Woodlands in South-Western Queensland

1976 ◽  
Vol 24 (2) ◽  
pp. 177 ◽  
Author(s):  
AJ Pressland
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Stand Density ◽  
Tree Density ◽  
Pan Evaporation ◽  
Permanent Wilting Point ◽  
The Mean ◽  
Acacia Aneura ◽  
Soil Moisture Status ◽  
Wilting Point

The important Australian fodder tree mulga (Acacia aneura F. Muell.) was thinned to densities ranging between 0 and 4000 trees ha-1 near Charleville, Queensland. Water use by the ensuing communities was studied from December 1971 to October 1973. Evapotranspiration over this 22 month period increased with tree density from 814 mm for the totally cleared plots to 852 and 891 mm for those plots supporting 4000 and 640 trees ha-1 respectively. Regression analysis was used to relate soil moisture to time since rain; it was established that the soil had dried to its permanent wilting point within 60 days of rain sufficient to recharge the soil to a depth of 135 cm. The mean apparent maximum evapotranspiration of the mulga communities was 4.7 mm day-1. The ratios of evapotranspiration to pan evaporation (Et/Eo) were influenced by both soil moisture status and tree density. Et/Eo ratios ranged between 0.55 and 0.07 in the summer of 1972, and between 1.05 and 0.05 the following summer. In the winters of 1972 and 1973 Et/Eo ratios ranged between 0.92 and 0.04, and 1.33 and 0.09 respectively. The significance of the results to production and management of mulga lands in south-western Queensland is discussed.

Influence of Fire and Edaphic Factors on Germination of the Arid Zone Shrubs Acacia aneura, Cassia nemophila and Dodonaea Viscosa

1990 ◽  
Vol 38 (3) ◽  
pp. 269 ◽  
Author(s):  
KC Hodgkinson ◽  
RE Oxley
Keyword(s):  
Soil Moisture ◽  
Arid Zone ◽  
Moisture Level ◽  
Fuel Load ◽  
Dodonaea Viscosa ◽  
Shrub Species ◽  
Soil Moisture Level ◽  
Germination Response ◽  
Acacia Aneura ◽  
Semi Arid

The germination of some shrub species may be enhanced following fire in shrublands and woodlands. This paper reports the germination response of Acacia aneura, Cassia nemophila and Dodonaea viscosa - common shrub species in semi-arid and arid woodlands - to laboratory fires over a range of intensities and durations. Seeds were subjected to fires of different intensities in the controlled environment of a glasshouse. Depth of seed placement in the soil, soil moisture level and amount and type of fuel influenced the percentage of seeds that germinated. Amounts of shredded paper fuel, equivalent to typical grass fuel levels in semi-arid woodlands did not enhance the germinability of seeds of any of the species, except for A. aneura on a moist or wet soil surface. A high, dense fuel load (simulating slow burning, low- intensity litter fires) either increased or decreased the germinability of surface and buried seeds of all species, depending upon soil moisture level and depth of seeds. The germination response to the heat of fires differed significantly between species: A . Aneura germination increased substantially at low levels of peak temperature up to 60°C whereas germination of C. nemophila increased to a lesser extent and D. viscosa was not affected at all over this low temperature range. Seeds of all species were killed by slow burning litter fires when the temperature exceeded 80°C. These results confirm the view that fire- promoted germination does not result from the burning of fine fuels per se but occurs only where there is litter buildup and when the soil temperature does not exceed the lethal threshold of 70-80°C.

Effect of Bearmat (Chamaebatia foliolosa) on Soil Moisture and Ponderosa Pine (Pinus ponderosa) Growth

Weed Science ◽  
1982 ◽  
Vol 30 (1) ◽  
pp. 98-101 ◽  
Author(s):  
John C. Tappeiner ◽  
Steven R. Radosevich
Keyword(s):  
Acetic Acid ◽  
Soil Moisture ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Tree Height ◽  
Wood Production ◽  
Pine Seedlings ◽  
Survival And Growth ◽  
Dichlorophenoxy Acetic Acid

An experiment was established in 1961 to determine the influence of bearmat (Chamaebatia foliolosa Benth.) competition on ponderosa pine (Pinus ponderosa Laws.) survival and growth. Ponderosa pine seedlings were planted in bearmat which was: (A) untreated, (B) sprayed with a mixture of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], and (C) eliminated by a combination of herbicide, clipping sprouts, and trenching to prevent root and rhizome invasion. Ponderosa pine survival after 19 yr averaged 9%, 66%, and 90%, respectively, for the three treatments. Tree height after 19 yr averaged 1.6, 1.9, and 5.7 m for treatments A, B, and C, respectively. Soil moisture use was initially less on the herbicide-treated than on the untreated plots, but bearmat quickly sprouted after application to compete with the pine seedlings for moisture. After 19 yr the bearmat was more dense and appeared to be more vigorous on the sprayed plots than on those receiving no treatment. We estimate that 75% reduction in net wood production could result after 50 yr on this site from bearmat competition.

Determination of the water use of two pairs of soybean isolines differing in stomatal frequency using a heat balance stem flow gauge

1995 ◽  
Vol 75 (1) ◽  
pp. 99-103 ◽  
Author(s):  
C. S. Tan ◽  
B. R. Buttery
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Heat Balance ◽  
Sap Flow ◽  
Stomatal Frequency ◽  
Flow Rates ◽  
High Soil Moisture ◽  
Stem Flow ◽  
Glycine Max L

Using heat-balance stem flow gauges, we were able to measure directly and continuously the sap flow rates in two pairs of soybean [Glycine max (L.) Merr.] isolines differing in stomatal frequency. Plants with high stomatal frequency transpired significantly more water than the low stomatal frequency plants at high soil moisture levels. Under low soil moisture levels, the water use rate decreased greatly for the high stomatal frequency plants. Plants with low stomatal frequency were able to maintain greater sap flow rates than those with high stomatal frequency. Higher leaf temperatures associated with the low stomatal frequency plants were likely due to lower transpiration rates which reduced evaporative cooling especially under well-watered conditions. Key words:Glycine max (L.) Merr., transpiration, water deficits

Contributions to the Biology of Mulga. II. Germination

1971 ◽  
Vol 19 (1) ◽  
pp. 39 ◽  
Author(s):  
PB Preece
Keyword(s):  
Arid Zone ◽  
New South ◽  
Germination Rate ◽  
Ambient Air ◽  
Laboratory Studies ◽  
South Wales ◽  
Carbon Dioxide Concentrations ◽  
Germination Behaviour ◽  
One Year ◽  
Acacia Aneura

Investigations into the germination behaviour of seed of the widespread Australian arid zone leguminous tree Acacia aneura Benth. are described. Hardseededness has been overcome in routine laboratory studies, but attempts to understand the mechanism by which it is overcome in nature were unsuccessful. The seed germinates equally well in the dark and in the light within the temperature range 15-36°C. Temperatures between 20 and 30° are optimal for germination, and carbon dioxide concentrations up to 5 % increase the germination rate above that displayed in ambient air. A simple model has been developed which suggests that seed of this species should have been available and should have germinated in c. one year in every nine, since records began in parts of western New South Wales where mulga regeneration is absent.

INFILTRATION CHARACTERISTICS OF A GUELPH LOAM SOIL FROM ANALYSIS OF HYDROLOGIC DATA

1965 ◽  
Vol 45 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. J. Percy ◽  
H. D. Ayers ◽  
L. R. Webber
Keyword(s):  
Soil Moisture ◽  
Management Practices ◽  
Graphical Analysis ◽  
Bare Ground ◽  
Infiltration Rates ◽  
Continuous Corn ◽  
Hydrologic Data ◽  
Loam Soil

Graphical analysis of 9 years of hydrologic data was used to derive 46 infiltration curves for 0.05-acre plots of Guelph loam. The rankings of infiltration rates under four management practices were: continuous corn < bare ground < oats after corn < corn after 2 years of hay. Mass infiltration decreased as soil moisture increased, and increased as the amount of rain during a storm increased.Mass infiltration tended to decrease with time on a plot planted continuously to corn for 9 years.

Ecological Studies of the Endangered Rutidosis leptorrhynchoides. II. Patterns of Seedling Emergence and Survival in a Native Grassland

1995 ◽  
Vol 43 (1) ◽  
pp. 13 ◽  
Author(s):  
JW Morgan
Keyword(s):  
Soil Moisture ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Moisture Stress ◽  
Seedling Mortality ◽  
Themeda Triandra ◽  
Established Plant ◽  
Survival And Growth ◽  
Growth Of Seedlings

The emergence, survival and growth of seedlings of the endangered Rutidosis leptorrhynchoides F.Muell. were followed in a Themeda triandra grassland during 1991 and 1992. The effect of summer irrigation on seedling survival was also investigated. Seedling emergence occurred in both years within 2 weeks of the 'autumn break' when soil moisture rose above 20%. Ninety percent of emergence was observed within 4 weeks of the onset of germination and 87% of seedlings were within 20 cm of an established plant. No emergence was observed after 8 weeks. Thirteen percent of the 1991 cohort survived for 14 months. Mortality of most seedlings (63%) was attributed to soil moisture stress in summer. Small seedlings (Ͱ4 3 leaves) were no more susceptible to drought than larger seedlings. Seventy two percent of the 1991 cohort produced four leaves before subsequently dying. In 1992, however, most early seedling mortality was amongst cotyledonary seedlings. No seedlings flowered in their first year. Above-ground growth was slow and by 14 months, 60% of surviving seedlings had seven or fewer live leaves. Irrigation in a year of below-average rainfall had no significant effect on the survival and growth of seedlings. This suggests that seedling recruitment is not restricted to climatically favourable years (i.e. is not episodic) but rather, is potentially on-going provided suitable microsites are available for seedling survival.

The growth and survival of young Mulga (Acacia aneura F. Muell) trees under different levels of grazing.

1985 ◽  
Vol 7 (2) ◽  
pp. 143 ◽  
Author(s):  
RF Brown
Keyword(s):  
Grazing Intensity ◽  
Growth And Survival ◽  
Continuous Grazing ◽  
Annual Consumption ◽  
C Stock ◽  
Complete Exclusion ◽  
Survival And Growth ◽  
Acacia Aneura ◽  
Possible Cause ◽  
Different Levels

The effects on the survival and growth of young mulga trees exposed to five levels of sheep graztng were monitored over bur years. The levels ranged from complete exclusion of domest~c stock to continuous grazing at a projected annual consumption rate of 20%, 35%, 50%, or 80% of the total available forage (grass, herbage, and accessible mulga leaf). Innially, all trees were less than 90 cm tall. Four years later, the ungrazed trees had more than doubled in he~ght whereas thegrazed trees were not significantly taller, irrespective of grazing intensity. Over 90% of the ungrazed trees had grown above the upper limit of sheep browsing (I20 cm) and their growth was considered unlikely to be prejudiced by subsequent grazing. Stem diameters nearly trebled in ungrazed mulga but much smaller Increases (averagmg25%) occurred in grazed plants. Overall, 36% of the young trees died. Most deaths occurred during the winter of 1980 and summer of 1982183 after protracted periods of dry weather. Grazing had little or no e,ffect on death rates. Even the lightest grazing arrested mulga growth and prevented the transition from low mulga to the tailer forms used for drought feeding. This is discussed as a possible cause of reported declines in drought reserves of mulga. The results of this study illustrate the need to ensure that grazing strategy is compatible with uninterrupted replacement of umbrella mulga (5-8 m high) cut for drought fodder.

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