Water Potential and Stomatal Conductance of Three Eucalyptus Species in the Mount Lofty Ranges, South Australia: Responses to Summer Drought

1980 ◽  
Vol 28 (6) ◽  
pp. 499 ◽  
Author(s):  
R Sinclair
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
South Australia ◽  
Late Summer ◽  
Distribution Patterns ◽  
The Other ◽  
Late Winter ◽  
Eucalyptus Species ◽  
Summer Drought ◽  
Factors Affecting

Water potential and stomatal conductance were measured for three eucalypt species: Eucalyptus obliqua L'Hérit., E. fasciculosa F. Muell. and E. leucoxylon F. Muell. Field sites were located in the Mt Lofty Ranges, S.A., near the lower altitudinal limits of the E. obliqua population, where this species begins to be replaced by one or other of the other two. Pairs of trees, one pair of each species, were selected at each site growing within a few metres of each other. Measurements were made in late winter 1977 and during the unusually dry summer of 1977-78. In late winter E. obliqua and E. fasciculosa results were similar. Both had dawn water potential maxima of approximately -0.4 MPa, and stomatal conductance was high throughout the day. By mid summer E. obliqua was suffering water stress. Dawn water potential maxima of -1.93 and -4.35 MPa were measured, and stomatal conductance was low, but not zero, throughout the day. Adjacent E. fasciculosa showed few signs of stress; dawn maximum water potential was -0.7 MPa, and stornatal conductances were high. By late summer both water potentials and stornatal conductances of E. obliqua were much lower than those of adjacent trees of either of the other two species. The significance of these differences is discussed in relation to factors affecting eucalypt distribution patterns.

Factors affecting the productivity of irrigated annual pastures. 1. Time of first irrigation in late summer-early autumn

1986 ◽  
Vol 26 (3) ◽  
pp. 297 ◽  
Author(s):  
CR Stockdale
Keyword(s):  
Nitrogen Content ◽  
Irrigation Treatment ◽  
Subterranean Clover ◽  
Late Summer ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Factors Affecting ◽  
Autumn And Winter ◽  
Clover Content

The influence of time of first irrigation (mid-February, early March, or late March) on the productivity of an annual pasture was studied for 3 years in northern Victoria. Beginning the irrigation of annual pastures in late summer instead of at the normal time of late March- April provided additional herbage in autumn and winter and did not adversely affect herbage production in late winter-early spring; up to 2.3 t/ha DM of additional herbage was obtained by mid June and 4.3 t/ha DM over the whole season. Earlier irrigation also increased the subterranean clover content of the pasture, resulting in herbage that was lower in digestibility and higher in nitrogen content than that in the other treatments. The benefit of early irrigation in increasing clover content may be offset by invasion by weeds. In this experiment, a potential weed problem in the earliest irrigation treatment appeared at the beginning of year 3.

Frost hardiness of commercial Eucalyptus species at different elevations

1989 ◽  
Vol 19 (10) ◽  
pp. 1235-1239 ◽  
Author(s):  
P. M. Hallam ◽  
J. B. Reid ◽  
C. L. Beadle
Keyword(s):  
Late Summer ◽  
Frost Hardiness ◽  
Late Winter ◽  
Eucalyptus Species ◽  
Good Growth ◽  
Significant Difference ◽  
Maximum Temperatures

Six Eucalyptus species, E. regnans F. Muell., E. delegatensis R.T. Bak., E. globulus Labill., E. nitens (Deane & Maid.) Maid., E. pauciflora Sieb. ex Spreng, and E. grandis Hill ex Maid., were sampled for determination of frost hardiness in March (late summer) and August (late winter) 1985 from trial plantings at four elevations in southern Tasmania. In March, there was a statistically significant difference between sites, but not between species or provenances. In August, significant differences between species, and for E. delegatensis between provenances, had developed. The species ranked in order of increasing frost hardiness as follows: E. regnans < E. grandis < E. globules = E. delegatensis (Maydena provenance) < E. pauciflora < E. nitens < E. delegatensis (Guildford provenance). Greatest frost hardiness was developed at the 60-m site (elevation), followed by (in decreasing order) the 650-m site, the 440-m site, and the 240- m site. This order corresponded to the minimum temperatures experienced at the sites. Conversely, greatest growth occurred at the 60-and 240-m sites followed by the 440-m site and then the 650-m site, corresponding to decreasing maximum temperatures. It is argued that good growth and productivity are possible on quite frost prone sites, provided suitable provenances are selected for planting.

Periodicity of Fine Root Growth in Jarrah (Eucalyptus marginata Donn Ex Sm.)

1983 ◽  
Vol 31 (3) ◽  
pp. 247 ◽  
Author(s):  
B Dell ◽  
IM Wallace
Keyword(s):  
Root Growth ◽  
Fine Root ◽  
Phytophthora Cinnamomi ◽  
Late Summer ◽  
Late Winter ◽  
Summer Drought ◽  
Root Pathogen ◽  
Eucalyptus Marginata ◽  
Fine Root Growth ◽  
Mycorrhizal Roots

The timing of new surface root growth in jarrah (Eucalyptus marginata) was followed for a 15-month period in the field. The periodicity of new root growth was similar for long roots, non-mycorrhizal and mycorrhizal root clusters. Root growth was initiated during two peak periods in spring (September-October) and following autumn rain (May-June). Little new root activity was recorded in late winter (August) or during summer drought. Rapid root growth occurred within 2 days of a storm (47 mm rain) in February. In addition, short roots formed after very light showers of rain (<5 mm) in late summer. Much of the framework for fine feeder roots was built up after autumn rain. In contrast to new long root growth which was equally spread between spring and late autumn, the majority of new mycorrhizal roots were produced from May to July. Root growth ceased when warm surface soils dried out and commenced when the soils were moist after rain. Much of the new root growth in jarrah occurred when the root pathogen Phytophthora cinnamomi was active in the soil.

scholarly journals Seasonal variations of snow chemistry at NEEM, Greenland

2011 ◽  
Vol 52 (58) ◽  
pp. 193-200 ◽  
Author(s):  
Takayuki Kuramoto ◽  
Kumiko Goto-Azuma ◽  
Motohiro Hirabayashi ◽  
Takayuki Miyake ◽  
Hideaki Motoyama ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Seasonal Variations ◽  
Ice Core ◽  
Late Summer ◽  
The Other ◽  
Late Winter ◽  
Surface Mass ◽  
Snow Chemistry ◽  
Double Peaks ◽  
Stable Isotopes Of Water

AbstarctWe conducted a pit study in July 2009 at the NEEM (North Greenland Eemian Ice Drilling) deep ice-coring site in northwest Greenland. To examine the seasonal variations of snow chemistry and characteristics of the drill site, we collected snow/firn samples from the wall of a 2 m deep pit at intervals of 0.03 m and analyzed them for electric conductivity, pH, Cl–, NO3–, SO42–, CH3SO3– (MSA), Na+, K+, Mg2+, Ca2+ and stable isotopes of water (δ18O and δD). Pronounced seasonal variations in the stable isotopes of water were observed, which indicated that the snow had accumulated regularly during the past 4 years. Concentrations of Na+, Cl– and Mg2+, which largely originate from sea salt, peaked in winter to early spring, while Ca2+, which mainly originates from mineral dust, peaked in late winter to spring, slightly later than Na+, Cl– and Mg2+. Concentrations of NO3– showed double peaks, one in summer and the other in winter to spring, whereas those of SO42– peaked in winter to spring. The winter-to-spring concentrations of NO3– and SO42– seem to have been strongly influenced by anthropogenic inputs. Concentrations of MSA showed double peaks, one in spring and the other in late summer to autumn. Our study confirms that the NEEM deep ice core can be absolutely dated to a certain depth by counting annual layers, using the seasonal variations of stable isotopes of water and those of ions. We calculated the annual surface mass balance for the years 2006–08. The mean annual balance was 176 mm w.e., and the balances for winter-to-summer and summer-to-winter halves of the year were 98 and 78 mm, respectively. Snow deposition during the winter-to-summer half of the year was greater than that during the summer-to-winter half by 10–20mm for all three years covered by this study.

DISTRIBUTION AND DENSITY OF CARABID BEETLES (COLEOPTERA) IN A PEST MANAGEMENT APPLE ORCHARD

1979 ◽  
Vol 111 (7) ◽  
pp. 759-770 ◽  
Author(s):  
N. J. Holliday ◽  
E.A.C. Hagley
Keyword(s):  
Pest Management ◽  
Cover Crop ◽  
Late Summer ◽  
Distribution Patterns ◽  
Horizontal Distribution ◽  
Apple Orchard ◽  
Soil Sampling ◽  
Carabid Beetles ◽  
Late Winter ◽  
The North

AbstractTwo soil sampling techniques were used over a 2 year period to examine the distribution of carabid beetles in a pest management apple orchard in southern Ontario. Soil coring was the most suitable technique for investigating temporal and vertical distribution patterns. Horizontal distribution of individual carabid species was best examined by sampling the rhizosphere of the cover crop only. Comparison of the soil sampling results with those obtained from pitfall traps showed that in late summer carabid larvae are subterranean in habit, as are adults of Bradycellus rupestris Say and Amara spp. Carabid density was highest (289.1 m−2) in late summer and fall, and lowest in late winter. In most samples carabid density was greatest in the rhizosphere of the cover crop and decreased rapidly with increasing depth: few beetles were found at depths greater than 30 cm. In August, densities of the commonest adult carabids were greatest close to trees in the orchard and decreased with increasing distance from trees. The distribution of carabid larvae was not related to distance from the tree, but densities of larvae were higher to the south of trees, and lower to the north.

scholarly journals Effect of Irrigation on Crabapple Growth and Water Relations During Field Production with In-Ground Fabric Containers

1994 ◽  
Vol 12 (2) ◽  
pp. 108-111
Author(s):  
R. Kjelgren ◽  
C. Spihlman ◽  
B.R. Cleveland
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Area ◽  
Water Relations ◽  
Osmotic Potential ◽  
Management Practices ◽  
Summer Drought ◽  
Irrigation Frequency ◽  
Trunk Diameter

Abstract Growth and water relations of irrigated and non-irrigated Malus sieboldii var. zumi produced with and without in-ground fabric containers in a field-nursery setting were investigated. Predawn and midday leaf water potential and midday stomatal conductance were measured periodically through the season, and trunk increment, leaf area, root growth, and osmotic potential were measured in late season. Water potential became more negative and stomatal conductance decreased in non-irrigated treatments during an extended mid-summer drought that resulted in less trunk diameter growth and leaf area. Trees grown in fabric-containers, both irrigated and non-irrigated, exhibited no detectable differences in water relations over the season. These trees did have fewer roots and less leaf area than the trees grown without fabric containers, indicating that in-ground fabric containers can limit growth even when irrigated. Non-irrigated trees in fabric containers were nonetheless affected by water stress as they had the least trunk growth and most negative osmotic potential of all treatments. Careful management practices would suggest increased irrigation frequency during production with in-ground fabric containers to avoid water stress.

Factors affecting the relative distribution of Atriplex vesicaria and Kochia sedifolia (Chenopodiaceae) in the arid zone of South Australia

1965 ◽  
Vol 13 (3) ◽  
pp. 419 ◽  
Author(s):  
BB Carrodus ◽  
RL Specht
Keyword(s):  
Experimental Approach ◽  
Surface Soil ◽  
Arid Zone ◽  
South Australia ◽  
The Other ◽  
Relative Distribution ◽  
Factors Affecting ◽  
Heavy Clay ◽  
Detailed Work ◽  
Normal Rainfall

The factors controlling the relative distribution of Atriplex vesicaria and Kochia sedifolia were obscure, and explanations in the literature unsatisfactory. This paper describes the results of an experimental approach to an understanding of these factors. A survey of the soils on which A. vesicaria and K. sedifolia are found in the arid zone of South Australia revealed that the distribution of the two species is usually correlated with the depth to which the soil is wetted by the normal rainfall. K. sedifolia, a deep-rooted species, is frequently found on soils which can be wetted to a depth of 2 ft or more. A. vesicaria, a shallow-rooted species, is found on soils in which a heavy clay subsoil or hardpan impedes penetration of water beyond 12 in. From experimental evidence it appears that: (1) either species can grow successfully in pots of the surface soil associated with the other species; (2) each community utilizes water at the same rate; (3) there is no difference between the two species in the rate of defoliation in response to drought conditions, when held at night either in a dry atmosphere or in one with a relative humidity exceeding 85 %; (4) A. vesicaria can reduce the percentage moisture in the soil to a significantly lower level than can K. sedifolia when subjected to drought. These observations are discussed in relation to field conditions, and hypotheses are proposed to explain why these two species are usually found in distinct communities. More detailed work is necessary to test these hypotheses. I.

Population and demographic patterns of rabbits (Oryctolagus cuniculus) at Roxby Downs in arid South Australia and the influence of rabbit haemorrhagic disease

1998 ◽  
Vol 25 (6) ◽  
pp. 655 ◽  
Author(s):  
Zoë Bowen ◽  
John Read
Keyword(s):  
Oryctolagus Cuniculus ◽  
South Australia ◽  
Late Summer ◽  
Early Summer ◽  
Myxoma Virus ◽  
Late Winter ◽  
Virus Vectors ◽  
Rabbit Haemorrhagic Disease ◽  
Demographic Patterns ◽  
Haemorrhagic Disease

Rabbit populations and demography were surveyed at Roxby Downs in arid South Australia from 1989 to 1997. Rabbit numbers typically peaked in late summer following breeding from late winter to early summer. After initial declines attributable to burrow flooding and increased populations of virus vectors, rabbit numbers increased by approximately 400% after significant rains. Introductions of Spanish rabbit flea, a vector of Myxoma virus, did not influence rabbit numbers but rabbit haemorrhagic disease (RHD) had a dramatic and sustained influence on rabbit numbers. The optimum times for release of RHD are discussed.

scholarly journals Seasonal population dynamics of Octopus vulgaris in the eastern Mediterranean

2006 ◽  
Vol 63 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Stelios Katsanevakis ◽  
George Verriopoulos
Keyword(s):  
Eastern Mediterranean ◽  
Late Summer ◽  
Main Peak ◽  
Octopus Vulgaris ◽  
Late Winter ◽  
Visual Census ◽  
The Common ◽  
Specific Growth Rates ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Abstract The population density of Octopus vulgaris was measured by visual census with scuba diving in coastal areas in Greece (eastern Mediterranean). A time-variant, stage-classified, matrix population model was developed to interpret the seasonal variation of octopus stage densities and to estimate several life cycle parameters. An annual and a semi-annual periodic cycle were found in the stage densities. A main peak of benthic settlement was observed during summer and a secondary, irregular one during late autumn. Two spawning peaks were estimated, a main one during late winter–spring and a secondary one during late summer–early autumn. More than 50% of the just-settled individuals will eventually die after 3 months. Mortality rate declines, as individuals grow larger, reaches a minimum approximately 6 months after settlement, and then grows again probably because of terminal spawning. The life expectancy of recently settled individuals (<50 g) during their summer peak is approximately 5 months. The lifespan of the common octopus is estimated to be between 12 and 15 months. The octopuses' mean specific growth rates (±s.d.) in their natural environment were 1.61 ± 0.30 d−1 for 50–200 g individuals and 1.19 ± 0.31 d−1 for 200–500 g individuals.

Factors Affecting Stomatal Conductance of Bracken Below a Forest Canopy

1984 ◽  
Vol 21 (2) ◽  
pp. 643 ◽  
Author(s):  
J. Roberts ◽  
J. S. Wallace ◽  
R. M. Pitman
Keyword(s):  
Stomatal Conductance ◽  
Forest Canopy ◽  
Factors Affecting
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