• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 13
  • 9
  • 5
  • 3
  • 1
  • Tagged with
  • 37
  • 37
  • 19
  • 16
  • 10
  • 9
  • 8
  • 8
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Water Use of Four Commonly Planted Landscape Tree Species in a Semi-Arid Suburban Environment

Bunnell, Michael Cameron 01 December 2015 (has links)
Native plant communities and agricultural land are commonly converted to urban areas as cities across the Western United States continue to grow and expand. This expansion is typically accompanied by afforestation where a common goal among communities is to maximize shade tree composition. Planted forests in these regions are commonly composed of introduced tree species native to mesic environments and their ability to persist is dependent on consistent irrigation inputs. Many potential ecosystem services may be derived from planting trees in urban and suburban areas; however, there are also costs associated with extensive afforestation, and shade tree cover may have significant implications on municipal water budgets. In this study I evaluate variation in daily and seasonal water use of regionally common suburban landscape tree species in the Heber Valley (Wasatch County, Utah). I had two primary objectives: (1) to identify and understand the differences in transpiration between landscape tree species in a suburban setting and (2) to assess the sensitivity of sap flux and transpiration to variation in vapor pressure deficit, wind speed, and incoming shortwave radiation. I used Granier's thermal dissipation method to measure the temperature difference (ΔT) between two sap flux probes. The empirical equation developed by Granier was used to convert ΔT into sap flux density (Jo) measurements, which were then scaled to whole-tree transpiration. There were consistent and substantial differences in sap flux between tree species. I found that Picea pungens under irrigated growing conditions, on average, had Jo rates that were 32% greater and whole tree water use (ET) rates that were 550% greater than all other species studied. The findings of Jo may be partially explained by xylem architecture and physiological control over stomatal aperture. However, the rate of water flux in the outermost portion of sapwood does not necessarily determine the magnitude of whole tree transpiration. Rather, ET in this study was largely explained by the combined effects of irrigation, tree size, and sapwood to heartwood ratio.
22

Ecologia funcional de árvores na Mata Atlântica = o papel de atributos morfológicos, grau de exposição da copa e altitude sobre o uso de água das espécies / Functional ecology of trees at the Atlantic Rain Forest : the roleof morphological attributes, crown exposure and altitude on water use

Rosado, Bruno Henrique Pimentel 17 August 2018 (has links)
Orientadores: Marcos Pereira Marinho Aidar, Rafael Silva Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T23:16:33Z (GMT). No. of bitstreams: 1 Rosado_BrunoHenriquePimentel_D.pdf: 5546425 bytes, checksum: c44175517f96f35f31d721d7439b5cfa (MD5) Previous issue date: 2011 / Resumo: O entendimento de como espécies de plantas utilizam água, requer a caracterização dos fatores que afetam o fluxo de água no contínuo solo-planta-atmosfera (SPA). Desta forma, esta tese reúne trabalhos nos quais investiguei como variações no uso de água de espécies arbóreas na Floresta Atlântica estão relacionadas a atributos morfológicos, grau de exposição da copa (EC) e à variação de fatores abióticos em função da altitude na Mata Atlântica. As altitudes estudadas, 100 e 1000 metros de altitude acima do nível do mar, correspondem às Florestas Ombrófila Densa de Terras Baixas (FODTB) e Montana (FODM). A maior radiação solar (RS) e demanda evaporativa do ar (DPV) associada à menor pressão atmosférica na FODM favoreceriam uma maior transpiração, criando situações de maior vulnerabilidade à variação na disponibilidade hídrica. No entanto, não se pode descartar que mesmo espécies que co-ocorrem em um mesmo ambiente podem apresentar diferentes capacidades de regular o uso de água devido ao papel de atributos morfofisiológicos sobre o SPA. Foram estudados alguns dos componentes do contínuo SPA tais como a densidade de comprimento de raízes finas (DCR) e repelência hídrica foliar (RHF), além de medidas diretas de fluxo de água do xilema. Variações em atributos funcionais e seu reflexo no uso de água das espécies se deram em função da EC e da variação dos fatores abióticos conforme aumento da altitude. Maiores DCR e RHF na FODM; regulação da transpiração noturna na FODM além de menores condutâncias totais associadas a atributos morfológicos indicaram ajustes associados ao uso da água. Estes resultados trazem novas contribuições para o entendimento do funcionamento de floresta tropicais chuvosas ao evidenciar que luz e nutrientes não podem ser considerados como os únicos fatores limitantes destes ambientes / Abstract: Understanding how different plant species and / or functional types use water requires characterization of the factors that affect the continuous soil-plant-atmosphere (SPA). This thesis presents a number of studies in which I investigated how changes in water use of tree species in the Atlantic Forest are related to morphological attributes, crown exposure (CE) and the variation of abiotic factors as a function of altitude in the Atlantic. The altitudes studied, 100 and 1000 meters above sea level, correspond to the lowland ombrophilous dense forest (LODF) and Montane (MODF). Potentially, the higher solar radiation, higher vapor pressure déficit and lower atmospheric pressure at the MODF, would drive higher transpiration rates leading to higher vulnerability to variation in water availability in comparison to the LODF. However, we can not disregard that even co-occurring species may show different abilities to regulate water use due to the role of morpho-physiological traits on the SPA. Were studied components that are part of the continuum SPA such as fine root length density (RLD), which indicates efficiency water absorption, leaf water repellency (LWR) and wood density, besides measurements of sap flow. Variations in functional attributes and its reflection on water use species that have were associated to CE and the variation of abiotic factors according to altitude. Higher RLD and LWR at the MODF; regulation of nighttime transpiration at the MODF and trend of lower total conductance in relation to the LODF indicate adjustments associated with the water use. These results provide important contributions to understanding tropical rain forest functioning and indicate that light and nutrients can not be considered as the only limiting factors at these environments / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal
23

Relações hídricas e crescimento do pequizeiro irrigado e adubado / Water relations and growth of souari nut trees irrigated and fertilized

Miranda, Raiane Ferreira de 17 February 2017 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2017-03-07T13:55:58Z No. of bitstreams: 2 Dissertação - Raiane Ferreira de Miranda - 2017.pdf: 9029827 bytes, checksum: 6b8f8f4ddaa3080a5d3e06d7971b47da (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-03-07T15:14:53Z (GMT) No. of bitstreams: 2 Dissertação - Raiane Ferreira de Miranda - 2017.pdf: 9029827 bytes, checksum: 6b8f8f4ddaa3080a5d3e06d7971b47da (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-07T15:14:53Z (GMT). No. of bitstreams: 2 Dissertação - Raiane Ferreira de Miranda - 2017.pdf: 9029827 bytes, checksum: 6b8f8f4ddaa3080a5d3e06d7971b47da (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-17 / The souari nut tree, native of the Brazilian Savannah, presents adaptation to the dry season and to poor soils. However, it is believed that in conditions of absence of water deficit and good soil fertility, the plant can develop better than in natural conditions, making commercial cultivation possible. Thus, the present study had as objective to evaluate the water relations and the growth of the souari nut trees in function of irrigation and organic fertilization. For this, 120 souari nut trees (from the 6 to the 8 year-old), spaced at 5.0 x 5.0 m were used in a randomized block experiment with six blocks and 16 plants per block, where four Treatments (IA: Irrigated and fertilizated, IN: Irrigated and no-fertilizated, SA: no-irrigated and fertilizated, SN: no-irrigated and no-fertilizated) in the scheme of subdivided plots. In Nov / 2014 the fertilization was of 12.5 kg of organic composting and 1.0 kg of Yorim, and in Nov / 2015, 5 kg of bovine manure and 2.5 kg of chicken manure per plant. The irrigation system used was a microsprinkler with a emitter per plant (Pressure = 10 mca, q = 43 L h-1, wet radius = 2 m), whereby, during the dry season, an average of 116.95 and 92,24 L plant-1 day-1 were applied in 2015 and 2016, respectively. Water relations evaluation consisted of foliar temperature monitoring (nov/2015 to jun/2016) and transpiration by means of sap flow density (out/2015 to may/2016) in irrigated and non-irrigated plants. As growth variables, the height and perimeter of the stem were evaluated monthly, crown area and root density at 6.5 and 7.1 year-old, respectively. The results showed that when irrigated the leaf temperature of the plant remains below the mean air temperature, regardless of the dry or rainy period, while without irrigation the plant presents in water deficit during the dry season. In dry conditions the mean perspiration of the souari nut tree is 24.09 L plant-1 day-1 and if irrigated on average 42.29 L plant-1 day-1. In spite of water supply and fertilization, the plant does not respond in growth in terms of height and stem perimeter. On the other hand, irrigation influences the canopy area, providing trees with larger canopy areas. When irrigated the souari nut tree presents distance and effective depth of the root system (80%) up to 2.00 m, and in dry conditions the roots are horizontally closer to the plant up to 1.60 m, in depth also concentrate up to 2,00m. / O pequizeiro, nativo do bioma Cerrado, apresenta adaptação à estação seca e a solos pobres. Entretanto, acredita-se que em condições de ausência do déficit hídrico e boa fertilidade do solo, a planta pode se desenvolver melhor que em condições naturais viabilizando seu cultivo comercial. Assim, o presente estudo teve como objetivo avaliar as relações hídricas e o crescimento do pequizeiro em função da irrigação e adubação orgânica. Para isso, foram utilizadas 96 plantas de pequi (do 6º. ao 8º. ano de idade), espaçadas a 5,0 x 5,0 m em experimento conduzido em blocos ao acaso com seis blocos e 16 plantas por bloco, onde foram avaliados quatro tratamentos (I.A.: Irrigação com adubação, I.N.: Irrigação sem adubação, S.A.: Sem irrigação e com adubação e S.N.: Sem irrigação e sem adubação) no esquema de parcelas subdivididas. Em Nov/2014 a adubação consistiu de 2,5 kg de material de compostagem e 1,0 kg de Yorim, e em nov/2015 foram aplicados 5 kg de esterco bovino curtido e 2,5 kg de cama de frango por planta. O sistema de irrigação utilizado foi microaspersão, com um microaspersor por planta (Pressão =10 mca, q = 43 L h-1, raio molhado = 2 m), pelo qual foram aplicados, no período de estiagem, em média 116,95 e 92,24 L planta-1 dia-1 em 2015 e 2016, respectivamente. A avaliação das relações hídricas consistiu no monitoramento da temperatura foliar (nov/2015 a jun/2016) e a transpiração por meio da densidade do fluxo de seiva (out/2015 a mai/2016) nas plantas irrigada e não irrigada. Como variáveis de crescimento avaliou-se a altura e perímetro do caule mensalmente, área da copa e densidade de raízes aos 6,5 e 7,1 anos de idade do pomar, respectivamente. Os resultados mostraram que quando irrigada a temperatura foliar da planta mantém-se abaixo da temperatura média do ar, independentemente do período seco ou chuvoso, enquanto que sem irrigação a planta apresenta-se em déficit hídrico durante a estação seca. Em condições de sequeiro a transpiração média do pequizeiro é de 24,09 L planta-1 dia-1 e se irrigada em média 42,29 L planta-1 dia-1. A despeito do fornecimento de água e adubação, a planta não responde em crescimento em termos de altura e perímetro do caule. Por outro lado, a irrigação influencia na área da copa, proporcionando árvores com áreas de copas maiores. Quando irrigado o pequi apresenta distância e profundidade efetiva do sistema radicular (80%) até 2,00 m, e em condição de sequeiro as raízes apresentam-se horizontalmente mais próximas à planta até 1,60 m e em profundidade concentram-se igualmente, até 2,00m.
24

ESTIMATION OF EVAPOTRANSPIRATION OF COTTONWOOD TREES IN THE CIBOLA NATIONAL WILDLIFE REFUGE, CIBOLA, ARIZONA

JETTON, AMITY J. 29 May 2008 (has links)
No description available.
25

Water Use of Hybrid Poplar (Populus deltoides Bart. ex Marsh × P. nigra L. “AF2”) Growing Across Contrasting Site and Groundwater Conditions in Western Slovakia

Fontenla‑Razzetto, Gabriela, Tavares Wahren, Filipa, Heilig, Dávid, Heil, Bálint, Kovacs, Gábor, Feger, Karl-Heinz, Julich, Stefan 22 March 2024 (has links)
The water use by short rotation coppices (SRC) has been a focus of ongoing research in the last decades. Nevertheless, investigations that consider site factors and present long-term monitoring of the components of the water balance are rare. This research quantified the tree-based transpiration in the 4th growing season of uncoppiced 1st rotational hybrid poplar stands (Populus deltoides Bart. ex Marsh × P. nigra L. “AF2”) in western Slovakia. The aim of the study was to determine the influence of meteorological and soil-related site conditions on transpiration rates. Three experimental plots were located in the Morava River floodplains, on loamy sand-textured soils with different groundwater accessibilities: higher, low, and fluctuating groundwater level. We measured sap flow (Heat Ratio Method), volumetric water content, matric potential, groundwater level, and meteorological variables throughout the growing season in 2019. The results indicated that transpiration in the three sites was almost constant during that period, which was characterized by distinct conditions. The average cumulative transpiration at the site with a higher groundwater level (1105 mm) was larger than at the site with a lower groundwater level (632 mm) and the site with fluctuating groundwater (863 mm). A principal component analysis (PCA) and correlation analysis identified that the contribution of meteorological and soil-related site variables to transpiration differed among the sites. Soil water availability and groundwater accessibility are critical variables for the water use of poplar SRC. We concluded that the combination of site conditions needs to be reconsidered for the expansion of sustainable short rotation plantations in Europe.
26

Experimentelle Untersuchung der Wasseraufnahme und der hydraulischen Eigenschaften des Wurzelsystems von sechs heimischen Baumarten / Experimental investigation of water uptake and hydraulic properties of the root system of six European tree species

Korn, Sandra 25 June 2004 (has links)
No description available.
27

Untersuchungen zur Dynamik des Nährstofftransports im Xylem von Pappeln unter besonderer Berücksichtigung der Stickstoffversorgung des Sprosses / Dynamic of the nutrient transport in the xylem of poplar

Siebrecht, Sylke 07 November 2000 (has links)
No description available.
28

Impact of tree species diversity on water and carbon relations in European forests / Impact de la diversité en espèces d'arbres sur les relations hydriques et carbonées dans les forêts européennes

Grossiord, Charlotte 02 October 2014 (has links)
La biodiversité favorise un grand nombre de fonctions et services écosystémiques des écosystèmes forestiers tels que la production de bois ou la résistance aux attaques d’insectes et aux maladies. Cependant l’impact de la diversité sur l’acquisition et l’utilisation de l’eau et du carbone reste largement méconnu dans ces écosystèmes. De plus, dans le contexte actuel de changement climatique, l’influence de la diversité sur la réponse des écosystèmes forestiers à des événements climatiques extrêmes tels que la sécheresse reste à étudier. L’objectif de ce travail est donc de déterminer l’impact de la diversité en espèces d’arbre sur d’importantes fonctions du cycle de l’eau et du carbone telles que la transpiration, la composition isotopique du carbone ou la profondeur d’extraction de l’eau à l’échelle de l’arbre et de l’écosystème sous des conditions contrastées dedisponibilité en eau du sol. Ce travail a été réalisé dans le cadre du projet FunDivEUROPE sur un réseau de parcelles forestières ainsi que dans des plantations expérimentales le long d’un gradient Nord-Sud en Europe afin de couvrir une importante gamme de conditions climatiques. Nos travaux ont montré une importante variabilité de la réponse à la diversité à l’échelle de l’arbre et de l’écosystème en termes de relations hydriques et carbonées à travers l’Europe. La diversité en espèces ne semble pas influencer les relations hydriques et carbonées des espèces et des écosystèmes forestiers dans des conditions non limitantes de disponibilité en eau. Cependant, un fort effet de la diversité a été observé en conditions de sécheresse pour certains types forestiers. A partir de ces résultats, je discute des mécanismes d’interaction entre espèces qui peuvent expliquer les effets observés. Nos données ont montré que l’influence de la diversité en espèces est fortement dépendante du contexte et peut êtremodifiée par les conditions environnementales locales et les conditions climatiques. En terme de gestion forestière, je suggère que pour certaines régions en Europe, promouvoir la diversité en espèces ainsi que contrôler la densité des parcelles doit être recommandé afin d’adapter les écosystèmes forestiers aux futures conditions climatiques / Biodiversity is known to support and boost a wide range of forest ecosystem functions and services like productivity and resistance against insect pests and diseases. However, whether tree species diversity also promotes water and carbon acquisition and use in forest ecosystems is still unclear. Furthermore, in the current context of global warming, information on how tree species diversity can influence the response of forest ecosystems to extreme climatic events such as drought are urgently needed. In this framework, the objective of my PhD thesis was to determine how tree species diversity influences important functions of the water and carbon cycle including transpiration, carbon isotope composition and water extraction depth at the tree- and ecosystem-Scale under contrasting soil water conditions. My work was conducted within the FunDivEUROPE project in a network of permanent forest stands and tree plantations across a North-South gradient in Europecovering a wide range of climatic conditions. I found considerable variability among species or forest types in the response of transpiration and carbon isotope composition at the tree- and ecosystem-Scale across Europe. Species diversity did not affect the water and carbon relations of tree species and forest ecosystems under non-Limiting soil water conditions. However, a strong effect of species diversity was observed under drought conditions in some forest types. Based on these data, I discuss the potential mechanisms of species interactions that may explain the observed patterns. I also point out that the influence of species diversity is highly context-Dependent, and changes with local environmental and climatic conditions. In terms of forest management applications, I suggest that, at least in some regions, controlling for tree species diversity along with stand density and total basal area could be recommended to help forests adapt to drier conditions
29

Hydrologické procesy a jejich dynamika v měnícím se klimatu a prostředí: Zkušenosti z výzkumu na různých časových a prostorových škálách / Hydrological processes and dynamics in the changing climate and environment: Lessons learned from multiple temporal and spatial scales

Su, Ye January 2019 (has links)
Hydrological processes and dynamics in the changing climate and environment: Lessons learned from multiple temporal and spatial scales Ye Su ABSTRACT Climate change, along with the changes in land use and land cover (LULC), is the key factor driving the changes in hydrological processes and dynamics in a basin. This thesis emphasized on understanding the impact of both long-term climate change and abrupt anthropogenic driven agricultural intensification or natural driven insect-induced forest disturbance on hydrological processes and dynamics at varying spatial and temporal scales in two diverting terrestrial environment. Two pattern-based investigations, one case study in a forest region in Central Europe and another in a semi-arid region in Central Asia, were aimed to answer the main research question "what are the responses of hydrological dynamics and the related hydro-geochemical conditions to climate change and certain changes in LULC at a basin-scale?". The long-term hydro-climatic dataset was used for conducting statistical analyses and establishing hydro-climatic modelling at the basin scale. We further conducted process-based studies, attempting to understand how and why the specific hydrological dynamics were altered at smaller spatial and temporal scales: (i) a catchment-scale tracer-based...
30

Water Fluxes in Soil-Pavement Systems: Integrating Trees, Soils and Infrastructure

de la Mota Daniel, Francisco Javier 31 January 2019 (has links)
In urban areas, trees are often planted in bare soil sidewalk openings (tree pits) which recently are being covered with permeable pavements. Pavements are known to alter soil moisture and temperature, and may have implications for tree growth, root development and depth, drought resilience, and sidewalk lifting. Furthermore, tree pits are often the only unsealed soil surface and are important for water exchange between soil and atmosphere. Therefore, covering tree pits with pavement, even permeable, may have implications for the urban water balance and stormwater management. A better understanding of permeable pavement on tree pavement soil system functioning can inform improved tree pit and street design for greater sustainability of urban environments. We conducted experiments at two sites in Virginia, USA (Mountains and Coastal Plain) with different climate and soil. At each location, we constructed 24 tree pits in a completely randomized experiment with two factors: paved with resin-bound porous-permeable pavement versus unpaved, and planted with Platanus x acerifolia 'Bloodgood' versus unplanted (n = 6). We measured tree stem diameter, root growth and depth, and soil water content and temperature over two growing seasons. We also monitored tree sap flow one week in June 2017 at the Mountains. In addition, we calibrated and validated a soil water flow model, HYDRUS-1D, to predict soil water distribution for different rooting depths, soil textures and pavement thicknesses. Trees in paved tree pits grew larger, with stem diameters 29% (Mountains) and 51% (Coastal Plain) greater. Roots developed faster under pavement, possibly due to the increased soil water content and the extended root growing season (14 more days). Tree transpiration was 33% of unpaved and planted pit water outputs, while it was 64% for paved and planted pits. In June 2016, planted pits had decreased root-zone water storage, while unplanted pits showed increased storage. A water balance of the entire experimental site showed overall decreased soil water storage due to tree water extraction becoming the dominant factor. HYDRUS-1D provided overall best results for model validation at 10 cm depth from soil surface (NSE = 0.447 for planted and paved tree pits), compared to 30- and 60 cm depths. HYDRUS-1D simulations with greater pavement thickness resulted in changes in predicted soil water content at the Coastal Plain, with higher values at 10- and 30-cm depths, but lower values at 60-cm depth. At the Mountains, virtually no difference was observed, possibly due to different soil texture (sandy vs clayey). Tree pits with permeable pavement accelerated tree establishment, but promoted shallower roots, possibly increasing root-pavement conflicts and tree drought susceptibility. Paved tree pits resulted in larger trees, increasing tree transpiration, but reduced soil evaporation compared to unpaved pits. Larger bare soil pits surrounded by permeable pavement might yield the best results to improve urban stormwater retention. Also, HYDRUS 1D was successful at simulating soil water content at 10-cm depth and may be valuable to inform streetscape design and planning. / PHD / Trees in cities are often planted in pavement cutouts (tree pits) that are usually the only available area for water exchange between soil and atmosphere. Tree pits are typically covered with a variety of materials, including permeable pavement. Pavements are known to modify soil water distribution and temperature, affecting tree growth, rooting depth, drought resilience, and sidewalk lifting. A better understanding of this system can inform tree pit and street design for greater sustainability. We constructed 24 tree pits at each of two regions in Virginia, USA (Mountains and Coastal Plain). These tree pits were paved with permeable pavement or unpaved, and planted with London Plane or unplanted. We measured stem diameter, root growth, and soil water content and temperature over two years and tree sap flow for one week in summer (Mountains only). We also used a soil water flow model, HYDRUS-1D, to predict water distribution for different rooting depths, soil textures and pavement thicknesses. After the first growing season trees in pavement were larger, with stem diameters 29% (Mountains) and 51% (Coastal Plain) greater. Roots developed faster under pavement, possibly due to increased soil water content and a 14-day increase in root growing season. Also, in June 2017, tree transpiration was 33% of unpaved-and-planted pit water outputs, and 64% of paved-and-planted pits. In June 2016, root-zone water storage decreased in planted pits but increased in unplanted pits. When considering the entire experimental site, soil water storage decreased, with tree water extraction being the dominant factor. HYDRUS-1D performed better at 10-cm soil depth than at 30- and 60-cm depths. At the Coastal Plain, HYDRUS-1D predicted higher soil water content at 10- and 30-cm depths with increased pavement thickness, but lower values at 60-cm depth. At the Mountains, there was no effect, possibly due to higher clay content. Permeable pavement accelerated tree establishment, but promoted shallower roots, increasing drought susceptibility and risk for root-pavement conflicts. Pavement resulted in larger trees and greater transpiration, but reduced soil evaporation. Larger bare-soil pits surrounded by permeable pavement might optimize stormwater retention.

Page generated in 0.061 seconds