Dissertations / Theses on the topic 'Shelterbelts'

In Ukraine, the largest user of natural resources is the agricultural complex. About 60% of the country's lands are used for agricultural purposes. During the years of independence, the system of land use in agriculture has completely changed. Emergence of a large number of owners and lessees of farmland increases the range of stakeholders in Agriculture and Natural Resources. New land users, in most cases, have no agronomic knowledge and take land and agro-ecosystems as a source of quick profits. Farmland cannot be considered only as an economic object, place to work and receive products or food. Fields, pastures, fallow and other farmland with surrounding elements and components of the ecosystem are a dynamic complex of vegetation, animals and microorganisms with nonliving environment interacting as a functional unit. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/31699

The spatial distribution of local evaporation from ground-based sources behind solid and porous windbreaks was studied in laboratory models for steady state and intermittent flows. Field observations of wind and turbulence characteristics (turbulence intensity, power spectra and integral length scale L) over surfaces whose zero displacement (d) and roughness length (z$ sb0$) had also been determined, were used to scale the laboratory simulations. Scaling parameters were z/z$ sb0$, $ sigma$/U, L/z$ sb0$ and Uz$ sb{0}$/K, where z, U, $ sigma$ and K are height, wind speed, standard deviation of velocity fluctuations and turbulent diffusivity, respectively. The 50% porosity barrier was found to be the most effective single-barrier set-up for the reduction of moisture loss.
Conditional sampling of fluctuations w' and q' of the wind and moisture, respectively, with sonic anemometer and fast-response Krypton hygrometer behind solid and porous windbreaks in the field, revealed frequency of occurrence, duration and intensity of those turbulent structures primarily responsible for moisture transfer.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on September 25, 2009) Thesis advisor: Dr. Mary Grigsby. Includes bibliographical references.

Thesis (M.S.) University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 20, 2007) Vita. Includes bibliographical references.

The research objective was to calibrate a model to simulate odour dispersion downwind from natural windbreaks and then, use this model to observe the effect of windbreak characteristics and climatic conditions on the size of the odour dispersion plume. Computational fluid dynamic (CFD) models were used for the simulations because of their capability in reproducing turbulent wind conditions. The model was initially calibrated to ensure the proper velocity recovery ratio (VRR), and then to reproduce odour plumes measured in the field by three groups of four panellists.
The visual and statistical analysis of the field panellist observations indicated that a windbreak with an optical porosity of 0.35 could reduce by 21% the length of the odour dispersion plume, as compared to a site without a windbreak. Also, these analyses indicated that the site with a windbreak offering an optical porosity of 0.55 had no significant impact on the length of the odour plume, as compared to the site without a windbreak.
The models selected for the simulations were the Fluent 6.2 standard k-epsilon and SST k-o models. Their odour dispersion calibration indicated that both models can accurately reproduce the field measured odour hedonic tone and odour concentration by transforming the odour mass fraction computed by the models into the hedonic tone with a power function, and then into the odour concentration with an exponential function. The correlations between the simulated and measured absolute HT and between the simulated and measured odour concentrations were statistically significant (P < 0.01). However, the SST k-o was preferred over the standard k-epsilon because it could physically better reproduce the high turbulence conditions created by the windbreak.
The SST k-o model simulations indicated that odour plume length was mostly affected by windbreak porosity and height, as well as distance from the source. In terms of climatic conditions, odour plume size was mostly affected for atmospheric stability conditions which generally established ambient wind speed and rate of change of temperature. Wind direction has an impact on the length of the odour plume and the formation of a fin intensifying odour concentration near the windbreak, where an angle of 45º produces the shortest odour plume and the largest fin.
Key words: Simulation; odour; dispersion; natural Windbreak; CFD.

The purpose of this thesis is the determination of a minimum market price for Short-Rotation Forestry (SRF) willow biomass grown in monoculture and windbreaks in Quebec and Ontario. Full cost budgeting was used and developed on a Microsoft Excel spreadsheet. Harvest cycles of 3 and 4 years for monoculture plantations, and 8 years for windbreaks were investigated. Estimates for establishment and other preharvest costs were obtained from mid-sized (5 hectares) commercial SRF willow plots in Quebec and Ontario.
For the monoculture plantations, irrespective of cycle length, and using the base case figures, the final delivery cost of willow biomass ranged between 74-126 $/odMg and 63--109 $/odMg based on current and projected costs respectively. These hold for yields between 7 and 11 odMg/ha/yr. Moreover, the 4-year cycle was revealed to be more economically efficient than a 3-year cycle. Along with yield, the main cost factors affecting the economics of SRF monoculture plantations are: harvesting, transportation to a processing plant, land lease management. For the two major energy markets, ethanol and electricity production (biomass in replacement of coal), SRF willow biomass in monoculture plantations does not appear to be a viable feedstock given present technology and yields. In the short run, a more promising outlet for willow biomass is space heat production for small buildings, farm complexes, etc. In this market, many potential buyers can afford to pay a higher price for biomass than ethanol or electricity utilities.
In the windbreak system, biomass could be produced for between 44 and 68 $/odMg, assuming that yields between 12 to 20 odMg/ha/yr can be achieved. At this price, windbreak biomass is not a competitive feedstock for ethanol or electricity generation, but is attractive for space heat production. (Abstract shortened by UMI.)

There is growing evidence that the achievement of biodiversity conservation objectives at the regional scale will have to take into account not only habitats within reserves, but also the contribution of semi-natural habitats in production landscapes. This requires knowledge of the conditions that maintain or enhance biodiversity in these suboptimal habitats. I focused on a system of forest patches and hedgerows in an agricultural landscape as habitats for dispersal-limited native forest herbs to (1) identify species-specific traits that appear to either limit or facilitate survival or colonization of forest herbs in hedgerows compared to forest patches, and (2) to evaluate the relative contribution of landscape and local variables in explaining patterns of forest herb species richness, abundance, and diversity in hedgerows. A fourth-corner analysis revealed that traits such as early spring flowering, ant dispersal or a lack of vegetative propagation can reduce the likelihood of native forest species to benefit from hedgerows. Conditional autoregressive models showed that landscape variables, specifically hedgerow age and neighboring forest area, largely account for species diversity in hedgerows.

Thesis (MScFor)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: The windbreak species near Wolseley (WoSl and WoS3) was Casuarina cunninghamiana. The windbreak species near Saron (SaSl) and Villiersdorp (ViSl) was Eucalyptus cladocalyx and Pinus radiata respectively. A shelter effect was indicated at ViSI (from northerly winds in winter/early spring 1999), and WoS3 (from southerly winds in late spring 1999). Wind speeds were consistently reduced in the leeward sheltered zone ofViSl and WoS3. To improve the correlation of the shelter effect, mild contaminating winds (comprising approximately 28% of the total data recorded at each site) were excluded for the prediction equations of the shelter effect at each site. Compared to the more exposed wind speeds at 1.0 H to the windward side, wind speeds at ViS] were reduced by 32% at 3.0 H. Compared to 11.0 H, wind speeds at ViSl were reduced by 49 and 46% at 3.0 and 1.0 H respectively. With r2 values above 93%, accurate linear prediction equations were produced. The early barley damage assessments indicated that damage was absent or negligible at 11.1 H to the lee, and significantly highest (X < 0.05) at 13.7 H to the lee and beyond. The crop shelter effect significantly increased (p < 0.05) barley head number, transformed proportion of total barley head mass from above-ground mass, potato tuber mass, potato above-ground mass total potato tuber number, small tuber number, and disproportionate tissue damage to the windward section of each plant. For WoS3, the shelter effect became pronounced with severe south-easterly winds. The average hourly wind speeds at 3.0 H dropped from 0.9 m / s (in the previous and less windy sampling period) to 0.8 m / s, despite the sharp increase in exposed wind speeds. Compared to 13.0 H, wind speeds were reduced by 73 and 32% at 3.0 and 7.0 H respectively. With r2 values above 94%, accurate linear prediction equations were produced. The crop shelter effect significantly increased (p < 0.05) sub-sample mass of lOO grains. At WoS3, strong and sustained wind speeds caused leeward soil temperature increases of up to 4°C at 3.0 H, compared to 11.0 H. Brief strong winds (characteristic of winds at ViSl) had little effect on the soil temperature differences. At ViSl, a deviation of soil moisture content between 3.0 and 11.0 H, following periods of recharge, indicated a potential soil-moisture conservation effect in the sheltered zone. This did not occur at WoS3, due partly to a very low soil moisture content that had little scope for variation; From the crop variations and the microclimate variations at both ViS 1 and WoS3, the maximum shelter effect extended to approximately 4.0 H, followed by an intermediate zone of diminishing shelter that extended to approximately 9.0 H. For ViSl, WoS3 and SaSl, a shading effect significantly reduced yields (p<0.05) at 1.0 H from the respective northern windbreak, compared to yields at 2.0 H. At ViS 1 and WoS3, soil probes did not indicate a depletion of soil moisture resulting from the respective windbreaks. Soil moisture competition was indicated on the northern side of the WoSl windbreak with drier conditions; where soil moisture levels at 1.0 and 3.0 H diverged from a negligible level to a 22% lower level (p > 0.05) at 1.0 H, compared to 3.0H.
AFRIKAANSE OPSOMMING: Die boomsoorte wat as windbreke gedien het was Casuarina cunninghamiana naby Wolseley (WoS 1 en WoS3), en Eucalyptus cladocalyx en Pinus radiata by Saron (SaS 1) en Villiersdorp (ViS 1) respektiewelik. Beskutting is aangetoon by ViS 1 (teen noordelike winde in winter/vroee lente 1999) en WoS3 (teen suidelike winde in laat lente 1999). Windspoed is konsekwent aan die lykant sones van ViS 1 en WoS3 verminder. Ten dien einde die korrelasie van die beskuttings effek te verbeter, is matige kontaminerende winde (ongeveer 28% van die totale waargenome data by elke plek) buite berekening gelaat vir die voorspellingsvergelykings van die beskuttingseffek. In vergelyking met die meer blootgestelde windspoede by 1.0 H aan die windkant, is windspoede by ViSl met 32% verminder by 3.0 H. In vergelyking met 11.0 H is windspoede by ViSl met 49 en 46% by 3.0 en 1.0 H respektiewelik verminder. Met r2 waardes hoer as 93%, is akkurate lineere voorspellingsvergelykings verkry. Die vroee gars skade opnames het aangetoon dat geen of minimale skade by 11.1 H aan die lykant aangerig is, en beduidend die hoogste (x< 0.05) by 13.7 Hen verder aan die lykant was. Die gewas beskuttins effek het beduidende toenames (p< 0.05) in garsare, getransformeerde verhouding van totale gars-are massa van bo-grondse massa, aartappelknol massa, aartappel bo-grondse massa, totale aantal aartappeiknolle, en oneweredige weefsel beskadiging aan die windkant van elke plant tot gevolg gehad. Vir WoS3 het die beskuttingseffek beduidend geword met baie sterk suidoostelike winde. Die gemiddelde uurlike windsnelhede by 3.0 H het van 0.9/ (in die vorige en minder winderige toetstydperk) tot 0.8 m/" verminder, ten spyte van die skerp toename in blootgestelde windsnelhede. In vergelyking met 13.0 H is windsnelhede met 73 en 32% by 3.0 en 7.0 H respektiewelik verrninder. Met r2 waardes hoer as 94% 15 akkurate lineere voorspellingsvergelykings verkry. Die gewas beskuttingseffek het sub-monster massa van 100 graankorrels beduidend (p< 0.05) verbeter. By WoS3 het sterk en volgehoue windsnelhede grondtemperature aan die lykant met tot 4°C by 3.0 H verhoog in vergelyking met 11.0 H. Kortstondige sterk winde (tipiese winde by ViS1) het weinig uitwerking op grondtemperatuursverskille gehad. By ViS1 het 'n afwyking van grondwaterinhoud tussen 3.0 en 11.0 H na tydperke van aanvulling, 'n potensiele grondwaterbewaringseffek in die beskutte gebied getoon. Soortgelyke tendense het nie by WoS3 voorgekom nie, gedeeltelik as gevolg van 'n baie lae grondwater inhoud wat nie veel kon varieer nie. Van die variasies wat in gewasse en mikroklimaat voorgekom het, by beide ViSl en WoS3, kan afgelei word dat maksimum beskutting tot by ongeveer 4.0 H verleen is, gevolg deur 'n intermediere sone van verminderende beskutting tot ongeveer 9.0 H. Vir ViS1, WoS3 en SaSl het 'n skadu-effek gewasopbrengs beduidend (p< 0.05) by 1.0 H verminder in vergelyking met opbrengste by 2.0 H. By ViS 1 en WoS3 het grondwater strooiingspeilers nie 'n uitputting van grondwater as gevolg van die windbreke getoon nie. Kompetisie vir grondwater is getoon aan die noordelike kant van die WoS1 windbreek met droer toestande. Grondwatervlakke by 3.0 H het minimaal maar by 1.0 H met 22% beduidend (p> 0.05) teenoor 3.0 H gedaal.

Shelterbelts were established in the Canadian Prairies as a means to protect soil from wind erosion. Knowledge gaps remain about shelterbelts' ecosystem services to the agro-landscape, hence hiding farmers' trade-offs in a changing agriculture. This research first investigated shelterbelts' effect on soil biological activity and fertility. Soil samples were collected in September 2012 from sheltered and non-sheltered fields in the Rural Municipality of Stanley, Manitoba. Results showed that shelterbelts promote higher soil biological activity, potentially correlated to the enhanced organic matter and micro-climate adjacent to shelterbelts. A survey was then conducted to explore shelterbelts' cultural services to the local community. Results indicated that while shelterbelts were perceived to significantly benefit community well-being, they were mainly recognised for agricultural functions. We conclude that shelterbelts are a significant element of both supporting and cultural ecosystem services, contributing to the prairie agro-system resilience. Further research and quantification of shelterbelts' socio-ecological services is recommended.

The role of shelterbelts within prairie agriculture is changing. In the past, shelterbelts have been promoted and adopted for soil stabilization and their ability to protect farmsteads and livestock from harsh prairie climates. In today’s agricultural landscape advances in production technology, an increase in farm size, and changes to policy have changed the circumstances in which decisions related to shelterbelts are made. The objective of this research is to identify the costs, benefits and the barriers to adoption and retention of shelterbelts that influence agricultural producers and landowners’ management decisions related to shelterbelts in the Canadian Prairies. In the summer of 2013, surveys of producers and landowners from throughout the province of Saskatchewan (and several from Alberta) were conducted. Using the information collected in the surveys, the costs and benefits (both economic and non-economic), and potential barriers to adoption and retention of shelterbelts that influence producer’s management decisions were identified and analyzed. This research identified that overall shelterbelts removal is increasing and that there are many barriers to adoption and retention for agricultural producers related to the economic costs. In addition, it was found that many of the benefits of shelterbelts are non-economic and more difficult for producers and landowners to recognize within their operations. Going forward, shelterbelts have the potential to play a major role in climate change mitigation by sequestering significant amounts of atmospheric carbon dioxide (CO2) into the soil and as biomass carbon in aboveground and belowground parts of planted shelterbelt trees or shrubs within the agricultural landscape. In addition, shelterbelts provide many ecological goods and services to landowners and society. In conclusion, understanding the context in which producers are making decisions related to shelterbelts within their operations is important from an agricultural production, climate change, and policy perspective.

Agroforestry systems are well known to enhance provision of multiple ecosystem services (e.g. wind speed reduction, habitat provision, carbon sequestration). These ecosystem services deliver both public and private benefits at a range of scales. For example, well-designed agroforestry systems enhance livestock productivity at the paddock scale by providing shelter from extreme temperatures, while also contributing to biodiversity conservation and climate change mitigation at broader scales. Despite growing global awareness of these benefits, adoption, particularly in some temperate industrialised agricultural landscapes including those in Australia, remains constrained. To encourage adoption of agroforestry and inform optimal design of agroforestry systems, new approaches are required to measure and communicate the broad range of benefits provided by agroforestry. Communication of farm-scale benefits is particularly important, as decisions relating to adoption and design of agroforestry in these landscapes generally fall to individual landowners. Natural capital accounting (NCA), a process of accounting for natural resources underpinned by ecosystem service valuation, could provide the framework for such an approach. While NCA is currently effectively applied at regional and national scales, this thesis examined whether NCA concepts can be usefully and practically applied at finer scales, such as individual farms or paddocks, to improve farm-scale decision-making and encourage adoption of agroforestry. The first of three research questions asked: can measurement and valuation of multiple ecosystem services, within the NCA framework, be usefully and practically applied for the purpose of encouraging adoption of agroforestry? To answer this question, existing concepts and methods for ecosystem service measurement and valuation were reviewed to assess their suitability for application in this context (Chapter 2). The review found that while some existing concepts (e.g. ecosystem service classification systems) are readily transferrable to agroforestry, established methods for ecosystem service measurement and valuation require adaptation (namely in how they deal with scale and choice of beneficiary) in order to be usefully applied to encourage adoption of agroforestry and inform decision-making. A discrete choice experiment (DCE) survey was also conducted with farmers from areas of Australia that hold potential for expansion of temperate agroforestry (Chapter 6). Results of this survey highlighted the importance of demonstrating ‘value for money’, or a return on investment in agroforestry, and revealed that farmers value a wide range of ecosystem services in agroforestry systems. These findings confirm the need for agroforestry valuation methods that incorporate multiple ecosystem services and acknowledge different forms of ‘value’. Ecosystem service valuation within the NCA framework provides this flexibility and is therefore useful in an agroforestry context. The second research question explored the issue of scale: which scale is most appropriate when applying NCA concepts for the purpose of encouraging agroforestry adoption and informing decision-making, and what implications does this choice of scale have for ecosystem service measurement and valuation? A review of the literature (Chapter 2) showed that because farmers are the key decision makers, NCA concepts should be applied at the farm or paddock scale and focus on farmers (or their investors) as the key beneficiaries. Chapter 2 also identified that there are significant gaps in the evidence base for measurement of ecosystem services by agroforestry assets at fine scales, particularly in the case of biodiversity-related services. Field experiments conducted in shelterbelt systems in the Midlands region of Tasmania, Australia (Chapters 3, 4, and 5), addressed several of these gaps. Chapter 3 showed that paddock-scale provision of a range of ecosystem services (wind speed reduction, wood production, carbon sequestration, and habitat provision) can be predicted based on measurement of vegetation structural characteristics. Chapters 4 and 5 found that shelterbelts support invertebrate communities that differ significantly from those in open pasture, and that they improve potential for pollination in adjacent paddocks. These findings contribute to the expanding evidence base for ecosystem service provision in agroforestry, at scales that are useful for informing decision-making by farmers. The third research question focused on the critical NCA concept of ‘condition’, asking: is vegetation structure a suitable and practical metric for assessing the condition of agroforestry assets? Results from the DCE (Chapter 6) showed that farmers had strong preferences for particular agroforestry design attributes (e.g. tree species selection) and further, that farmers are motivated to make design choices that will maximise benefits in alignment with their objectives. Many of the ecosystem services identified as being important to farmers (e.g. wind speed reduction) are influenced by vegetation structure (e.g. shelterbelt porosity). Chapter 3 examined whether vegetation structure offers a practical solution to the issue of condition assessment, by quantifying the impact of shelterbelt tree species selection (Pinus radiata, Eucalyptus nitens, and mixed native species) on specific structural attributes (e.g. height, porosity, and floral diversity) that determine fine-scale provision of key ecosystem services. Species selection, in addition to shelterbelt age, was found to significantly affect structure, and therefore delivery of services and benefits at fine scales. However, Chapters 4 and 5 found that shelterbelt tree species selection, and therefore structure, had relatively low influence on composition of invertebrate communities within and adjacent to shelterbelts. Findings from Chapters 3-5 show that while structure serves as a practical condition metric that is useful for informing agroforestry design, tracking flows of some services (e.g. biodiversity) may require consideration of broader landscape-scale condition metrics such as connectivity and complexity. Overall, this thesis demonstrates that with some adaptation, NCA concepts (e.g. condition assessment, ecosystem service measurement, and valuation) can be practically and usefully applied to agroforestry systems at the farm scale. The thesis shows that NCA concepts can be used to highlight the wide range of values provided in agroforestry systems, thereby building a more holistic business case for agroforestry that will appeal to a wider range of farmers and investors. Ultimately, this will assist in increasing adoption of agroforestry by farmers. The thesis also shows that application of NCA concepts to agroforestry will assist in informing design decisions (e.g. tree species selection), enabling farmers to design systems which maximise benefits that are important to them. Expanding this approach to consider both private and public values could also be useful in guiding development of policies aimed at enhancing broader benefits of agroforestry, such as biodiversity conservation and climate change mitigation.