Effect of Drought and Defoliation on the Susceptibility of Eucalypts to Cankers Caused by Endothia gyrosa and Botryosphaeria ribis

1990 ◽  
Vol 38 (6) ◽  
pp. 571 ◽  
Author(s):  
KM Old ◽  
R Gibbs ◽  
I Craig ◽  
BJ Myers ◽  
ZQ Yuan
Keyword(s):  
Water Stress ◽  
Soluble Carbohydrates ◽  
Eucalyptus Regnans ◽  
South Eastern ◽  
Eastern Australia ◽  
Branch Dieback ◽  
Crown Dieback ◽  
Canker Development ◽  
Insect Attack ◽  
South Eastern Australia

Seedlings, saplings and mature eucalypts were susceptible to infection by Endothia gyrosa and Botryosphaeria ribis. Eucalyptus regnans and E. delegatensis were more susceptible than E. grandis and E. saligna. In trees not subjected to stress, cankers were limited in extent and often healed. When trees were defoliated, either manually or by severe insect attack, stem concentrations of both starch and soluble carbohydrates were reduced and canker development in some pathogen/host combinations was increased. Seedlings subjected to water stress were not predisposed to canker formation. The association of E. gyrosa with branch dieback of rural eucalypts suffering from chronic defoliation suggests that canker fungi contribute to the crown dieback syndrome in south-eastern Australia.

Use of nest trees by the mountain brushtail possum (Trichosurus caninus) (Phalangeridae : Marsupialia). IV. Transitions between den trees

1998 ◽  
Vol 25 (6) ◽  
pp. 611 ◽  
Author(s):  
A. H. Welsh ◽  
D. B. Lindenmayer ◽  
C. F. Donnelly ◽  
A. Ruckstuhl
Keyword(s):  
Statistical Models ◽  
Brushtail Possum ◽  
Simulation Studies ◽  
Eucalyptus Regnans ◽  
South Eastern ◽  
Eastern Australia ◽  
Mountain Ash ◽  
Central Highlands ◽  
Individual Based Simulation ◽  
South Eastern Australia

Statistical models of the patterns of den-tree choice by the mountain brushtail possum (Trichosurus caninus) at Cambarville in the mountain ash (Eucalyptus regnans) forests of the central highlands of Victoria, south-eastern Australia are presented. These models enable us to predict, for a particular possum, the choice of den tree on the basis of patterns of recent den-tree usage and are required for individual-based simulation studies. The models show that the pattern of den-tree use is more complicated than might have been expected, in the sense that it is animal-specific, and that old animals exhibit more complicated patterns of den-tree choice than young ones.

On which timescale(s) do optimal adjustments to vegetation function confer resilience? A case study in South-Eastern Australia

2021 ◽  
Author(s):  
Manon Sabot ◽  
Martin De Kauwe ◽  
Andy Pitman ◽  
Belinda Medlyn ◽  
Silvia Caldararu ◽  
...  
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Optimality Theory ◽  
Land Surface ◽  
Future Climate Change ◽  
Leaf Biomass ◽  
Plant Hydraulics ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

<p>Droughts have been implicated as the driver behind recent vegetation die-off across a variety of hydroclimates and are projected to drive greater mortality under future climate change. Predicting ecosystem resilience to future drought requires a predictive capacity, which is currently lacking in state-of-the-art land surface models (LSMs) that rely on simplified empirical relationships to represent the impacts of water stress on vegetation. Novel approaches that optimise stomatal conductance with respect to plant photosynthetic and hydraulic functions have been shown to reduce the biases of LSM gas exchange predictions during drought. These approaches also offer a pathway to further develop mechanistic optimality theory, e.g. pertaining to leaf drought deciduousness. But on what timescale(s) does vegetation function adjust to maximise resource investment? We explore the following timescales of optimality within a simple LSM: (i) instantaneous (regulating canopy gas exchange); (ii) monthly (regulating the investment of nitrogen in photosynthetic capacity); and (iii) seasonal to annual (water stress legacies on plant hydraulics). We use observations from a temperate woodland in South-Eastern Australia to test which optimisation timescales and processes are best supported and whether competing timescales can operate together, both under well-watered conditions and during a severe multi-year drought, and from the leaf-scale to the ecosystem-scale. The insights gained help us characterize how adjoined allocation processes, like leaf biomass adjustment, relate to leaf carbon uptake and plant water status through time (e.g. leaves can be shed to mitigate drought stress or built from structural storage pools when water is not limiting), therefore conferring additional resilience.</p>

Long-season canola (Brassica napus L.) cultivars offer potential to substantially increase grain yield production in south-eastern Australia compared with current spring cultivars

2013 ◽  
Vol 64 (9) ◽  
pp. 901 ◽  
Author(s):  
Brendan Christy ◽  
Garry O'Leary ◽  
Penny Riffkin ◽  
Tina Acuna ◽  
Trent Potter ◽  
...  
Keyword(s):  
Water Stress ◽  
Grain Filling ◽  
Superior Performance ◽  
Yield Potential ◽  
Average Yield ◽  
South Eastern ◽  
Eastern Australia ◽  
Spring Type ◽  
Short Season ◽  
South Eastern Australia

Average yield of canola in the high-rainfall zone (HRZ) of southern Australia are about half the predicted potential yield based on seasonal water supply. Current cultivars of canola that are available to growers were not bred specifically for the HRZ and tend to be short-season types aimed at escaping water stress during grain filling in the drier regions of the cropping belt. In the HRZ, these cultivars fail to utilise all available growing-season water due to early maturity. Field experimentation and crop simulation studies across the HRZ landscape of south-eastern Australia were used to determine the increased yield potential of longer-season canola cultivars compared with short-season cultivars. In this study the Catchment Analysis Tool spatial modelling framework was used to determine the expected canola yields of three cultivars across the entire HRZ of south-eastern Australia. Hyola50 (‘spring-short’) was used to represent the current recommended spring-type canola cultivar within the HRZ and was evaluated against an unreleased long-season spring-type cultivar CBI8802 (‘spring-long’) and a newly released winter-type cultivar Taurus (‘winter’). Spring-long outperformed spring-short across much of the study area. Yield advantages of winter over spring-short were mainly confined to the coastal fringe of Victoria and Tasmania and small pockets in New South Wales where at one location the average yield over 50 growing seasons exceeded spring-short by up to 60% or 1.4 t/ha. The superior performance of spring-long, (up to 17% or 0.9 t/ha at one location) was over a wider area than winter (26.4 compared with 8.8 million ha for winter) and although the magnitude of the yield increase over spring-short was not as great as winter at some locations, the overall result determined that spring-long had the greater production potential. The superior performance of spring-long beyond the HRZ challenges the trend of selecting earlier maturing cultivars by current breeders following the abnormal sequence of dry years in an attempt to minimise yield loss due to water stress during grain filling. This study has provided breeders, growers and advisors with information on where in the HRZ a longer-season canola cultivar can be grown to improve overall crop productivity. It has also provided evidence that new canola types may be required to maximise grain yields not only for the HRZ but potentially also in lower rainfall regions.

Changing patterns of pasture production in south-eastern Australia from 1960 to 2015

2020 ◽  
Vol 71 (1) ◽  
pp. 70
Author(s):  
Ruchika S. Perera ◽  
Brendan R. Cullen ◽  
Richard J. Eckard
Keyword(s):  
Water Stress ◽  
Growth Rates ◽  
Seasonal Pattern ◽  
Growth Patterns ◽  
Wagga Wagga ◽  
Stress Growth ◽  
Pasture Production ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

The seasonal pattern of pasture production and its variability from year to year are important for pasture-based livestock production systems in south-eastern Australia because they influence key strategic decisions such as stocking rate and timing of the reproductive cycle. In this study, the effects of observed climate variations over the period 1960–2015 on pasture growth patterns were investigated by using a biophysical modelling approach. Pasture growth rates were simulated using DairyMod biophysical software at five sites ranging from high-rainfall, cool temperate at Elliott in Tasmania to medium-rainfall, warm temperate at Wagga Wagga in southern New South Wales. Annual pasture yields showed a small increasing rate of 50 kg DM/ha.year at Elliott and 40 kg DM/ha.year at Ellinbank (P < 0.05), whereas other sites showed no significant trend over time. A cross-site analysis of seasonal average pasture growth rates predicted under four different discrete periods of 14 years each showed that winter growth has increased steadily through time (P = 0.001), and spring pasture growth rate has decreased (P < 0.001) in 2002–15 compared with the earlier periods. Year-to-year pasture yield variability (coefficient of variation) during autumn and spring seasons has also increased (P < 0.05) across sites in the period 2002–15 compared with 1998–2001. At each site, the number of spring days with water stress (growth limiting factor_water <0.7) was ~10 times greater than the number of days with temperature stress (growth limiting factor_temperature <0.7). There was an increase in the number of days with water stress at Wagga Wagga, and increased heat stress at Wagga Wagga and Hamilton (P < 0.05) in the most recent period. These results highlight the importance of incorporating more heat-tolerant and deep-rooting cultivars into pasture-based production system. Although previous studies of climate-change impact have predicted increasing winter growth rates and a contraction of the spring growing season in the future (2030), this study provides clear evidence that these changes are already occurring under the observed climate in south-eastern Australia.

The use of nest trees by the mountain brushtail possum (Trichosurus caninus) (Phalangeridae : Marsupialia). V. Synthesis of studies

1998 ◽  
Vol 25 (6) ◽  
pp. 627 ◽  
Author(s):  
D. B. Lindenmayer ◽  
A. Welsh ◽  
C. F. Donnelly
Keyword(s):  
Brushtail Possum ◽  
Adult Males ◽  
Eucalyptus Regnans ◽  
South Eastern ◽  
Eastern Australia ◽  
Mountain Ash ◽  
Central Highlands ◽  
General Synthesis ◽  
South Eastern Australia

A general synthesis is presented of the key results of a series of studies of den tree use by the mountain brushtail possum (Trichosurus caninus) at Cambarville in the mountain ash (Eucalyptus regnans) forests of the central highlands of Victoria, south-eastern Australia. The project produced a range of unexpected results including (1) the number of den trees used, (2) the extent of den sharing, especially among adult males, (3) the overlap in denning ranges of animals, and (4) the predictability of transitions between den trees. Possible reasons for these findings are outlined. We also discuss the limitations of our study, how it could be improved if it were to be repeated, and some of the important implications of the findings for the management of forests where T. caninus occurs.

Use of Den Trees by Leadbeater's Possum (Gymnobelideus Leadbeateri)

1996 ◽  
Vol 44 (6) ◽  
pp. 625 ◽  
Author(s):  
DB Lindenmayer ◽  
RA Meggs
Keyword(s):  
Radio Tracking ◽  
Eucalyptus Regnans ◽  
Breeding Female ◽  
South Eastern ◽  
Risk Of Predation ◽  
Eastern Australia ◽  
Mountain Ash ◽  
Central Highlands ◽  
Leadbeater's Possum ◽  
South Eastern Australia

The results of a radio-tracking study of the uses of den trees by Leadbeater's possum (Gymnobelideus leadbeateri McCoy) at Cambarville in the mountain ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, south-eastern Australia, are described. Animals were radio-tracked for three periods of 5-20 days in July 1990, November 1990 and July 1991. A total of 14 individuals was tracked and they occupied 11 different trees with hollows on the 10-ha study site. Preliminary findings showed that some animals moved between hollows in different trees, and most animals used two or more trees. The distances between utilised trees usually exceeded 50 m. Possible reasons for the den-swapping behaviour include attempts to either or both relieve burdens of ecto-parasites and to reduce the risk of predation. There were several examples, in each of the three radio-tracking periods, of two or more radio-collared adult breeding female animals simultaneously co-occupying the same nest tree. This result was different from some of the general findings of an earlier study of G. leadbeateri at Cambarville.

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