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Wang H.,CAS Institute of Botany | Wang H.,Beijing Academy of Agriculture and Forestry Sciences | Wang H.,CAS Research Center for Eco Environmental Sciences | Zhao P.,CAS Institute of Botany | And 5 more authors.
Journal of Plant Ecology | Year: 2012

Aims: Nighttime sap flow of trees may indicate transpiration and/or recharge of stem water storage at night. This paper deals with the water use of Acacia mangium at night in the hilly lands of subtropical South China. Our primary goal was to reveal and understand the nature of nighttime sap flow and its functional significance. Methods: Granier's thermal dissipation method was used to determine the nighttime sap flux of A. mangium. Gas exchange system was used to estimate nighttime leaf transpiration and stomatal conductance of studied trees. Important Findings: Nighttime sap flow was substantial and showed seasonal variation similar to the patterns of daytime sap flow in A. mangium. Mean nighttime sap flow was higher in the less precipitation year of 2004 (1122.4 mm) than in the more precipitation year of 2005 (1342.5 mm) since more daytime transpiration and low soil water availability in the relatively dry 2004 can be the cause of more nighttime sap flow. Although vapor pressure deficit and air temperature were significantly correlated with nighttime sap flow, they could only explain a small fraction of the variance in nighttime sap flow. The total accumulated water loss (EL) by transpiration of canopy leaves was only ∼2.6-8.5% of the total nighttime sap flow (Et) during the nights of July 17-18 and 18-19, 2006. Therefore, it is likely that the nighttime sap flow was mainly used for refilling water in the trunk. The stem diameter at breast height, basal area and sapwood area explained much more variance of nighttime water recharge than environmental factors and other tree form features, such as tree height, stem length below the branch, and canopy size. The contribution of nighttime water recharge to the total transpiration ranged from 14.7 to 30.3% depending on different DBH class and was considerably higher in the dry season compared to the wet season. © 2012 he Author. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China. All rights reserved.

Xia K.,CAS Kunming Institute of Botany | Daws M.I.,Energy Resources of Australia Ltd. | Hay F.R.,International Rice Research Institute | Chen W.-Y.,CAS Kunming Institute of Botany | And 2 more authors.
South African Journal of Botany | Year: 2012

The fruit biology of Quercus subgenus Quercus has received considerable attention. However, considerably less is known about the fruit (hereafter referred to as seed) biology of subgenus Cyclobalanopsis which is distributed mainly in tropical and sub-tropical Asia. Consequently, we investigated the responses to desiccation of seeds of 11 species from subgenus Cyclobalanopsis and compared these with responses of 11 species from subgenus Quercus from both China and Europe. Similar to species in the subgenus Quercus, we found that all 11 subgenus Cyclobalanopsis species had desiccation-sensitive (recalcitrant) seeds. For the 22 species, which had seed dry masses spanning 0.57 to 6.41. g, there were wide differences in drying rates, but drying rate was not related to either seed dry mass or oil content. Drying rates also varied across the individual seeds within a species. These differential drying rates within a seed resulted in some individual seeds remaining significantly moister than the mean water content which may explain the apparent ability of some seeds of several species e.g. Quercus schottkyana to tolerate desiccation. © 2011 Elsevier B.V.

Hart B.T.,Water Science Pty Ltd | Taylor M.,Macquarie University | Iles M.,Energy Resources of Australia Ltd | Kyle G.,Gundjehmi Aboriginal Corporation | Sinclair G.,Energy Resources of Australia Ltd
Australasian Journal of Environmental Management | Year: 2015

Conflicts between indigenous people and mining companies have occurred in many countries and over many years, with the pressure for mining companies to improve their performance leading to a growth of corporate social responsibility concepts. Energy Resources of Australia and the Gundjeihmi Aboriginal Corporation (representing the Mirarr people) sought to resolve a number of long-standing issues relating to surface water management and monitoring associated with the Ranger Uranium Mine. This article summarises the process adopted and discusses the main factors that underpinned the success of the project. © 2015 Environment Institute of Australia and New Zealand Inc.

Ma L.,South China Agricultural University | Rao X.,CAS South China Botanical Garden | Lu P.,Energy Resources of Australia Ltd | Huang S.,South China Agricultural University | And 3 more authors.
Journal of Soils and Sediments | Year: 2015

Purpose: Large areas of land have been impacted by acidic mine drainage. These sites could potentially be re-vegetated for growing energy plants. Conventional phytoremediation method may fail because the pH of some mine drainage and contaminated soils can reach 2.0. Thus, it is necessary to screen acid-tolerant plants as pioneers to rehabilitate those severely acidified areas. Materials and methods: In the first phase of this study, seven levels of low pH media were used to estimate the acid-tolerant ranges of three plant species for 1 month. In the second phase, 50 commonly cultured plant species from 17 families, native in Guangdong Province of China or introduced from Australia, were evaluated for acid tolerance at three pH levels which were chosen based on results in the first phase. Results and discussion: We found that Acacia auriculiformis could survive and nodulate at pH ≥2.0, Acacia confusa and Melaleuca armillaris could survive at pH ≥2.5 but A. confusa nodulate at pH >3.5. In the second phase, 12 plant species, in addition to A. auriculiformis, can survive in pH 2.0 media. Conclusions: No family or genus commonality in acid tolerance was found. Two of these tolerant species, i.e., A. auriculiformis and Jatropha carcas, could potentially be planted as an economically and ecologically viable option for acid mine remediation due to their potential function as biofuel feedstock. © 2015, Springer-Verlag Berlin Heidelberg.

Ma L.,State Key Laboratory for Conservation and Utilization of Subtropical Agro bioresources | Rao X.,CAS South China Botanical Garden | Lu P.,Energy Resources of Australia Ltd | Bai S.H.,Griffith University | And 5 more authors.
Environmental Science and Pollution Research | Year: 2015

Eucalyptus spp. is a dominant tree genus in Australia and most Eucalyptus spp. are canopy dominant species. In Australian natural forests, Eucalyptus spp. commonly are associated with understorey legumes which play a crucial role for ecological restoration owing to their nitrogen (N) fixing ability for replenishing the soil N lost after frequent prescribed burning. This study aimed to explore to what extent physiological responses of these species differ 7 and 12 years after last fire. Two most common understorey Acacia spp., Acacia leiocalyx and A. disparrima, as well as one non-leguminous Eucalyptus resinifera, were studied due to their dominance in the forest. Both A. leiocalyx and A. disparrima showed higher carbon (C) assimilation capacity, maximum photosynthetic capacity, and moderate foliar C/N ratio compared with E. resinifera. A. leiocalyx showed various advantages compared to A. disparrima such as higher photosynthetic capacity, adaptation to wider light range and higher foliar total N (TNmass). A. leiocalyx also relied on N2-fixing ability for longer time compared to A. disparrima. The results suggested that the two Acacia spp. were more beneficial to C and N cycles for the post burning ecosystem than the non-N2-fixing species E. resinifera. A. leiocalyx had greater contribution to complementing soil N cycle long after burning compared to A. disparrima. © 2015, Springer-Verlag Berlin Heidelberg.

Lu P.,Darwin Lab | Lu P.,Energy Resources of Australia Ltd.
Acta Horticulturae | Year: 2013

Water status in trees is commonly studied by measuring leaf water potential with a pressure bomb, but due to mango's excessive latex exudation, leaf water potential measurements can not be reliably measured this way. We have measured xylem sap flow in the tree trunk, microvariation of branch diameter (microdendrometry), and leaf gas exchange to study mango water relations. The main Australian mango cultivar 'Kensington Pride' is very sensitive to air dryness, more so than most Florida cultivars. Both sap flow (tree water use) and twig/branch shrinkage have been shown to be good plant-based indicators of plant water status and been successfully used to control irrigation. However, at the present time, both techniques are far from being practical or economical enough to be used by growers for their irrigation scheduling. A low cost, farmer friendly tool for irrigators, 'FullStop' wetting front detectors, was developed by CSIRO in Australia. 'FullStop' is a simple device buried in the ground in the rooting zone, which will tell the irrigators when to switch off irrigation. This system has great potential as an aid to irrigation decision making. © ISHS 2013.

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