Investigating the photosynthetic and hydraulic trade-off during drought recovery in eucalypts

Thesis (PhD)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Stomatal regulation plays a vital role in maintaining the water status of a plant by minimising water loss, however, decreases in stomatal conductance can lead to reductions in carbon uptake. The stomata balance a trade-off between water loss and carbon gain. The hydraulic system and stomatal conductance are closely linked but play opposing roles within a plant. The hydraulic system ensures that there is a sufficient water supply to leaves, while stomatal conductance regulates the loss of water from the leaves. During periods of drought, reductions in hydraulic conductance due to embolism formation can be seen, however stomatal regulation can help reduce embolism formation or prevent runaway cavitation during drought. Understanding how plant hydraulics and stomatal regulation influence production rates is becoming more important to model stomatal responses in a changing climate, especially for Eucalyptus species which is often grown in drought prone environments. Plants use a wide range of strategies to reduce or mitigate the negative impact of embolism formation, with this study focusing on the strategies utilised by commercially significant Eucalyptus hybrids. Two Eucalyptus hybrids, E. grandis X camaldulensis (GC) and E. urophylla X grandis (UG), where subjected to a drought-recovery treatment where they were periodically droughted. During the experimental period the stomatal responses, together with transpiration rates, photosynthetic capacity and biomass allocation was measured. Hydraulic measurements together with CT-scan imaging was also utilised to determine whether these plants can recover lost hydraulic pathways post-drought, and what the underlying mechanism for this might be. During the study two distinct hydraulic strategies were observed. GC was more resistant to embolism formation compared to UG, however GC showed lower levels of hydraulic recovery after rewatering. The drought responses could also be split into a resilient v. a resistant response, with the more resilient hybrid, UG, maintaining stomatal conductance throughout drought periods running the risk of hydraulic failure, however with the ability to recover lost hydraulic pathways through refilling post- drought. This is in comparison with the resistant strategy seen in GC, where water loss during drought was minimised, however this also reduced carbon uptake and production. From this study the stomatal responses could also be accurately modelled using a gain-risk model that assumes stomata optimise the trade-off between water loss and carbon gain. It was however clear, that the strategy used by plants need to be considered when using a gain-risk model, with the gain-risk model performing better for the Eucalyptus hybrid that utilised a resistant strategy, since plants that uses a resilient strategy will maintain stomatal conductance during drought, regardless of the hydraulic risk. The use of alternative models was also investigated during this study, with Machine Learning models being able to accurately predict stomatal responses on a global scale. Major increases in tree mortality are predicted due to changes in climate. To properly predict these changes, accurate models of plant responses to water limitations and other environmental changes are therefore becoming increasingly important for effective forest management. Understanding how hydraulic traits and stomatal regulation covary, can help model drought-induced tree mortality in a changing climate.AFRIKAANSE OPSOMMING: Die regulasie van gaswisseling deur die huidmondjies is belangrik aangesien dit nie net die verlies van water deur transpirasie reguleer nie, maar ook die opname van CO2 wat nodig is vir fotosintese en produksie. Die hidroulise sisteem van ‘n plant en huidmondjies is gekoppel, maar speel teenoorgestelde rolle. Die hidrouliese sisteem beheer hoeveel water beskikbaar is vir die plant, terwyl die huidmondjies water verlies deur transpirasie beheer. Tydens droogtes, word die hidrouliese geleiding van water deur die plant bellemer deur die vorming van embolisme/lugborrels. Die huidmondjies kan wel die verspreiding van hierdie lugborrels verminder of verhoed deur water verlies te beheer. Dit is dus belangrik om te verstaan wat die interaksie tussen die huidmondjies en die hidrouliese sisteem van ‘n plant is om akurate modelle van gaswisseling te bou, veral vir Eucalyptus spesies, aangesien hulle gereeld in droogte geteisterde areas geplant word. Plante geskik van ‘n verskeidenheid van strategieë om die negatiewe impak van embolisme te vermider. Die studie het dus gefokus op die strategieë wat Eucalyptus kruise gebruik. Die gaswisseling en groei was gemeet van twee Eucalyptus kruise, E. grands X camaldulensis (GC) en E. urophulla X grandis (UG), tydens ‘n droogte eksperiment waar die plante vir sekere periodes nie water ontvang het nie. Meetings van die hidroulise geleiding en hidroulise einskappe was ook gemeet deur gebruik te maak van beide traditionele metodes, sowel as rekenaartomografie-skanderings, om te bepaal of die plante van die embolisme/lugborrels in die hidrouliese sisteem kan vul na ‘n droogte. Tydens die studie was dit duidelik dat die twee Eucalyptus kruise twee verskillend hidrouliese strategieë benut. GC was meer bestand teen droogte en die vorming van embolisme in vergelyking met UG, maar GC kon nie die embolisme in die hidroulises sisteem weer vul met water na die droogte nie. Die strategieë wat benut was kon ook beskryf word as ‘n weerstandbiedige strategie teenoor ‘n veerkragtige strategie. UG het ‘n veerkragtige strategie benut, waar gaswisseling gehandhaaf was tydens droogte, maar het ‘n hoër risiko gehad dat die hidrouliese sisteem misluk, terwyl GC ‘n weerstandbiedige strategie gehandhaaf het, waar gaswissinling and water verlies deur transpirasie verminder was, maar so ook CO2 opname. Tydens die study kon ons ook die gaswisseling voorspel deur ‘n wins-risiko model te gebruik wat aaneem dat die huidmondjies ‘n balans vind tusen water verlies en CO2 opname. Dit was egter duidelik dat die hidrouliese strategieeë in ag geneem moet word, aangesien die model meer akuraat was vir plante wat ‘n weerstandbiedige strategie benut. Dit is aangesien ‘n plant wat ‘n veerkragtige strategie benut gaswisseling sal handhaaf tydens droogte, ongeag die hidrouliese risiko. Ondersoek was ook ingestel om alternatiewe modelle te gebruik om gaswisseling te modelleer en dit was gevind dat masjienleermodelle ook gebruik kan word. Grootskaalse sterftes van bome word verwag asgevolg van klimaats verandering. Om die impak van dit te voorspel, is dit dus belangrik om akkurate modelle van gaswisseling in reaksie tot klimaats verandering te ontwikkel. As ons verstaan hoe die hidrouliese en gaswisseling sisteme van plante reageer, kan ons beter modelle bou om boom streftes te voorspel.Doctora

Module 1. Renewable energy and local development

To start the course, we will initially focus on the nature and characteristics of three natural and renewable resources: the sun, the wind, and the biomass. Although basically the three of them are obtained from the sun (solar rays themselves, movements of air caused by the heat of the sun, and energy to grow plants) their characteristics differ substantially from each other and this strongly defines the technology used to make them profitable

Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm

Abstract— Online transportation has become a basic requirement of the general public in support of all activities to go to work, school or vacation to the sights. Public transportation services compete to provide the best service so that consumers feel comfortable using the services offered, so that all activities are noticed, one of them is the search for the shortest route in picking the buyer or delivering to the destination. Node Combination method can minimize memory usage and this methode is more optimal when compared to A* and Ant Colony in the shortest route search like Dijkstra algorithm, but can’t store the history node that has been passed. Therefore, using node combination algorithm is very good in searching the shortest distance is not the shortest route. This paper is structured to modify the node combination algorithm to solve the problem of finding the shortest route at the dynamic location obtained from the transport fleet by displaying the nodes that have the shortest distance and will be implemented in the geographic information system in the form of map to facilitate the use of the system. Keywords— Shortest Path, Algorithm Dijkstra, Node Combination, Dynamic Location (key words

Climate Change and Environmental Sustainability-Volume 1

Climate change has been widely recognised as a major challenge to the world, with significant environmental, economic and social consequences. Given this, addressing climate change is an urgent and profound task of society, a complex and difficult mission of several generations. To address the challenge of climate change, there is a need to develop a holistic climate change mitigation and adaptation framework that can cover as many climate-related topics as possible and connect as many stakeholders as possible across the globe. This book is an important one, bringing together key climate-related topics, including climate-induced impact assessment, environmental vulnerability and resilience assessment, greenhouse gas emission dynamics and sequestration, climate change mitigation and adaptation strategies in addition to climate-related governance. Results reported in this book are conducive to a better understanding of the climate emergency, climate-related impacts and the solutions. We expect the book to benefit decision makers, practitioners and researchers in different fields such as climate modelling and prediction, forest ecosystems, land management, urban planning and design, urban governance in addition to institutional operation. Prof. Bao-Jie He acknowledges Project NO. 2021CDJQY-004, supported by the Fundamental Research Funds for the Central Universities. We appreciate the assistance from Mr. Lifeng Xiong, Mr. Wei Wang, Ms. Xueke Chen and Ms. Anxian Chen at the School of Architecture and Urban Planning, Chongqing University, China

The occurrence and origin of salinity in non-coastal groundwater in the Waikato region

Aims The aims of this project are to describe the occurrence, and determine the origin of non-coastal saline groundwater in the Waikato region. High salinity limits the use of the water for supply and agricultural use. Understanding the origin and distribution of non-coastal salinity will assist with development and management of groundwater resources in the Waikato. Method The occurrence of non-coastal groundwater salinity was investigated by examining driller’s records and regional council groundwater quality information. Selected wells were sampled for water quality analyses and temperatures were profiled where possible. Water quality analyses include halogens such as chloride, fluoride, iodide and bromide. Ratios of these ions are useful to differentiate between geothermal and seawater origins of salinity (Hem, 1992). Other ionic ratio approaches for differentiating sources and influences on salinity such as those developed by Alcala and Emilio (2008) and Sanchez-Martos et al., (2002), may also be applied. Potential sources of salinity include seawater, connate water, geothermal and anthropogenic influences. The hydrogeologic settings of saline occurrence were also investigated, to explore the potential to predict further occurrence. Results Numerous occurrences of non-coastal saline groundwater have been observed in the Waikato region. Where possible, wells with relatively high total dissolved solids (TDS) were selected for further investigation. Several groundwater samples are moderately saline and exceed the TDS drinking water aesthetic guideline of 1,000 g m-3 (Ministry of Health, 2008). Selected ion ratios (predominantly halogens) were used to assist in differentiating between influences on salinity such as seawater and geothermal. Bromide to iodide ratios, in particular, infer a greater geothermal influence on salinity, although other ratios are not definitive. The anomalously elevated salinity observed appears natural but nevertheless has constrained localised groundwater resource development for dairy factory, industrial and prison water supply use. Further work may show some relationship with geology or tectonics, which could assist prediction of inland saline groundwater occurrence

Renewable Energy

Renewable Energy is energy generated from natural resources - such as sunlight, wind, rain, tides and geothermal heat - which are naturally replenished. In 2008, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood burning. Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generation), followed by solar hot water/heating, which contributed with 1.3%. Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided some 0.8% of final energy consumption. The book provides a forum for dissemination and exchange of up - to - date scientific information on theoretical, generic and applied areas of knowledge. The topics deal with new devices and circuits for energy systems, photovoltaic and solar thermal, wind energy systems, tidal and wave energy, fuel cell systems, bio energy and geo-energy, sustainable energy resources and systems, energy storage systems, energy market management and economics, off-grid isolated energy systems, energy in transportation systems, energy resources for portable electronics, intelligent energy power transmission, distribution and inter - connectors, energy efficient utilization, environmental issues, energy harvesting, nanotechnology in energy, policy issues on renewable energy, building design, power electronics in energy conversion, new materials for energy resources, and RF and magnetic field energy devices

Cyber-Human Systems, Space Technologies, and Threats

CYBER-HUMAN SYSTEMS, SPACE TECHNOLOGIES, AND THREATS is our eighth textbook in a series covering the world of UASs / CUAS/ UUVs / SPACE. Other textbooks in our series are Space Systems Emerging Technologies and Operations; Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD); Disruptive Technologies with applications in Airline, Marine, Defense Industries; Unmanned Vehicle Systems & Operations On Air, Sea, Land; Counter Unmanned Aircraft Systems Technologies and Operations; Unmanned Aircraft Systems in the Cyber Domain: Protecting USA’s Advanced Air Assets, 2nd edition; and Unmanned Aircraft Systems (UAS) in the Cyber Domain Protecting USA’s Advanced Air Assets, 1st edition. Our previous seven titles have received considerable global recognition in the field. (Nichols & Carter, 2022) (Nichols, et al., 2021) (Nichols R. K., et al., 2020) (Nichols R. , et al., 2020) (Nichols R. , et al., 2019) (Nichols R. K., 2018) (Nichols R. K., et al., 2022)https://newprairiepress.org/ebooks/1052/thumbnail.jp