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Understanding of the hydrological cycle and processes such as interception span as far back as the times of the Renaissance, when Leonardo da Vinci (1452-1519) first described it. However, there remains a gap in the knowledge of both canopy and litter interception in South African forest hydrology. Interception is typically considered to constitute only a small portion of total evaporation and in some models is disregarded or merely lumped with total evaporation, and not considered as a separate process. Interception is a threshold process, as a certain amount of water is required before successive processes such as infiltration and runoff can take place. Therefore an error introduced in modelling interception, especially disregarding it, will automatically introduce errors in the calibration of subsequent models/processes. In this study, field experiments to assess these two poorly understood hydrological processes, viz. canopy and litter interception were established for the three main commercial forestry genera in South Africa, namely, Pinus, Acacia and Eucalyptus as well as an indigenous Podocarpus henkelii stand, thus, accounting for interception of “broad leaf”, “compound leaf” and “needle leaf” trees in order to provide further insight into these processes. The study took place at two locations in the KwaZulu-Natal Midlands over a period of three years. The first site is the Two Streams catchment, located in the Seven Oaks area, about 70km north-east of Pietermaritzburg where the study on the commercial plantation species took place. The second site was the Podocarpus henkelii stand in Karkloof near Howick, 40km north of Pietermaritzburg. From the field data collected (cf. Chapter 2) it was observed that canopy storage capacity, an important parameter governing interception, was not constant and changed with rainfall intensity, with lower intensity events resulting in a higher storage capacity. Building on these findings, a physically based canopy interception model that is based on the well known Gash model was developed, and is referred to herein as the “variable storage Gash model”. While canopy interception is dependent on many factors including the storage capacity, potential evaporation, rainfall intensity and rainfall duration, the litter interception is largely dependent on the storage capacity due to the evaporative drivers under the canopy such as radiation, temperature and wind speed being moderated by the above canopy. From these finding, a litter interception model based on idealised drying curves from litter samples collected at the study sites was also developed (cf. Chapter 3). From the field data, it was found that the canopy interception for Eucalyptus grandis, Acacia mearnsii and Pinus patula was 14.9, 27.7 and 21.4% of mean annual precipitation (MAP) respectively. The simulated canopy interception using the “variable storage Gash model” was 16.9%, 26.6% and 23.3% for E. grandis, A. mearnsii and P. patula respectively. The litter interception measured for E. grandis, A. mearnsii and P. patula was found to be 8.5, 6.6 and 12.1% of MAP respectively, while the simulated litter interception using the idealised drying curve model corresponded well with the measured results and were 10.1%, 5.4% and 13.4% for E. grandis, A. mearnsii and P. patula respectively. The idealised drying curve model is site and species specific and is therefore not transferable to other locations. Conversely, the “variable storage Gash model” is transferable as it is not site and species specific, and relies on readily measureable and available information. Building on field studies, this was then used to simulate the canopy interception for Eucalyptus, Acacia mearnsii and Pinus in South Africa (including Lesotho and Swaziland) for all quinary catchments in which commercial forestry could be grown, i.e. a mean annual precipitation of greater than 600 mm.year-1 (cf. Chapter 4). It was found that, depending on the location and genus, canopy interception loss can be as high as 100 to 300 mm per year or approximately 10% to 40% of MAP. This relates to a mean interception loss of between 1.0 and 3.0 mm per rainday, highlighting the spatial variability of canopy interception. To further investigate the spatial variability of canopy interception, at various spatial scales, remote sensing technology was applied to estimate leaf area index (LAI) for use in modelling/estimating canopy storage capacity and canopy interception (cf. Chapter 6). The NDVI, SAVI and Vogelmann 1 vegetation indices were used in the estimation of the LAI. It was found the Vogelmann 1 index produced the best results. As models to estimate canopy interception typically require LAI and storage capacity, it was calculated that the ability to estimate these parameters over large areas is valuable for water resources managers and planners. An often neglected consideration of canopy and litter interception is its role in determining the water use efficiency (WUE) of a forest stand (cf. Chapter 5). This component of the study was undertaken in an indigenous Podocarpus henkelii stand as well as a commercial Pinus patula stand in Karkloof in the KwaZulu-Natal Midlands. The sap flow (transpiration) was measured in both the P. henkelii and P. patula stands using the using the Heat Pulse Velocity (HPV) technique in order to determine the productive green water use. The canopy and litter interception was measured in the P. henkelii site, but was modelled in the P. patula site using the “variable storage Gash” and idealised drying curve models, in order to estimate the non-productive green water use. It was found that the canopy and litter interception for P. henkelii was 29.8% and 6.2% respectively, while the modelled canopy and litter interception for P. patula was 22.1% and 10.7% respectively. If only the productive green water use (transpiration) is considered, then the water use efficiency of P. henkelii and P. patula was found to be 7.14 g.mm-1 and 25.21 g.mm-1 respectively. However, from a water management perspective it is important to consider the total green water use efficiency (transpiration + interception), which reveals a significantly lower water use efficiency of 3.8 g.mm-1 and 18.8 g.mm-1 for P. henkelii and P. patula respectively. To extend the study to a globally relavent issue, the possible impact of climate change on canopy interception was investigated, as forests growth is critically linked to climate (cf. Chapter 7). To achieve this, the CABALA model was used to model LAI and transpiration of Eucalyptus grandis and Pinus patula under 9 different climate change scenarios, including changes in temperature, rainfall and atmospheric CO2. The simulated LAI values from the CABALA model for all 9 climate scenarios were then used to simulate canopy interception using the “variable storage Gash model”. Results show that LAI may increase by as much as 24% and transpiration may decrease by as much as 13%, depending on the scenario, location and tree species. However, it was found that canopy interception does not change greatly, leading to the conclusion that under climate change conditions, canopy interception may not become a more dominant component of the hydrological cycle than it currently is as the changes under climate change are likely to be less than the natural variability from year to year. However, canopy interception remains an important consideration for water resources management and planning both currently and in the future. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

I investigated oribatid mite assemblages in a beech-maple forest in southwestern Quebec. I first examined the effects of four forest stand types (American Beech (Fagus grandifolia) dominated, Sugar Maple (Acer saccharum) dominated, mixed deciduous and coniferous plantations) and three open site types (agricultural field, fallow pasture and unmanaged hay field) in structuring oribatid mite assemblages. My second study focused on the effects of changes in litter depth (a factor that varies by stand type) on the structure of oribatid assemblages. / Stand type was shown to be an important factor in determining oribatid mite abundances, species richness and assemblage composition. Results from the second study confirm this, but revealed no effect of changes in litter depth on oribatid mite assemblages. These findings serve to demonstrate that while examining specific environmental factors as determinants of oribatid mite diversity and distribution is important, more general factors such as habitat type cannot be ignored.

Alternative fuels are becoming more important as fossil fuels become more expensive. This thesis describes the production and properties of a bio-oil produced from waste biomass, in this case chicken litter. A higher quality fuel was produced through thermal and chemical upgrading of the raw bio-oil; this fuel is similar in some respects to fossil fuels, as it has a high hydrocarbon content and energy density comparable to gasoline. Combustion of liquid fuels commonly occurs in clouds of droplets, and studying the evaporation of single liquid drops provides information on the evaporation characteristics of the fuel as a whole. Droplet evaporation tests on the chicken litter fuel were carried out using the suspended droplet/moving furnace technique. For some tests, a fine wire thermocouple was used as the droplet suspension in order to measure the distillation characteristics of the fuel. An existing computational model based on continuous ther- modynamics was used to model the evaporation of the fuel. The modelled composition of the fuel was based on an existing pyrolysis field ionization mass spectrometry (Py-FIMS) analysis and used five major groups of compounds. The properties for these groups re- quired for the model were determined using several prediction methods and the values then used in a numerical model. Model predictions of droplet temperatures calculated for the fuel showed good agree- ment with the measured temperatures, indicating that the modelled composition gave an accurate picture of the fuel. Droplet evaporation histories also agreed well with mea- surements, but were not capable of reproducing the observed disruption of the droplet produced by internal boiling at higher temperatures, nor the formation of a solid residue at the end of evaporation. Further enhancements to the model should allow the prediction of residue formation.Model predictions of droplet temperatures calculated for the fuel showed good agree- ment with the measured temperatures, indicating that the modelled composition gave an accurate picture of the fuel. Droplet evaporation histories also agreed well with mea- surements, but were not capable of reproducing the observed disruption of the droplet produced by internal boiling at higher temperatures, nor the formation of a solid residue at the end of evaporation. Further enhancements to the model should allow the prediction of residue formation.

Eksperimentas buvo atliktas su 90 mišrūnių kiaulių, suskirstytų į bandomąsias grupes, atsižvelgiant į jų kilmę, lytį ir pradinį kūno svorį. Kiaulės buvo suskirstytos į šešias bandomąsias grupes (15 gyvūnų kiekvienoje grupėje): 1 grupė - gyvūnai šeriami visaverčiais pašarais ir laikomi ganykloje, 2 grupės - gyvūnai šeriami visaverčiais pašarais ir laikomi tvarte, garduose su kraiko pakratais, 3 grupė - gyvūnai šeriami visaverčiais pašarais ir laikomi tvarte, garduose be kraiko pakratų, 4 grupė - gyvuliai šeriami visaverčiais pašarais ir liucernos pašarais, laikomi lauke, grupė 5 - gyvuliai šeriami visaverčiais pašarais ir liucernos pašarais, laikomi tvarte, garduose su kraiko pakratais, 6 grupė - gyvuliai šeriami visaverčiais pašarais ir liucernos pašarais, laikomi tvarte, garduose be kraiko. Tyrimo objektas: penimų kiaulių elgsena atsižvelgiant į šėrimą ir laikymo būdus (tvarte ar vasaros stovyklose) Trimo tikslas: nustatyti laikymo sistemų (tvarte ar vasaros stovyklose) ir šėrimo (pilnavertis pašaras ir/arba papildytas liucernos pašaru) poveikį skirtingais amžiaus laikotarpiais penimų kiaulių elgsenai. Išvados. Analizuojant skirtingus penėjimo laikotarpius, nustatyti kiaulių elgsenos ypatumai ir ryšys su produktyvumu. Pirmoje ir antroje penėjimo fazėje (apie 50 kg ir 100 kg) nustatyti įtakojantys veiksniai produktyvumą susiję su poilsio periodų, judėjimo aktyvumų. Kiaulės augintos be kraiko, daugiau laiko skirdavo poilsiui, buvo mažiau aktyvios, ir agresyvesnės... [toliau žr. visą tekstą] / The experiment was performed on a total of 90 hybrid pigs divided into experimental groups based on their origin (litter), sex and initial body weight. The pigs were assigned to six experimental groups (15 animals per group): group 1 – animals fed a complete diet and kept freerange, group 2 – animals fed a complete diet and kept indoors in pens with litter bedding, group 3 - animals fed a complete diet and kept indoors in pens without litter bedding, group 4 – animals fed a complete diet and alfalfa forage, kept free-range, group 5 - animals fed a complete diet and alfalfa forage, kept indoors in pens with litter bedding, group 6 - animals fed a complete diet and alfalfa forage, kept indoors in pens without litter bedding. All management systems were animal welfare-friendly. Both at the first and second stage of fattening (approx. 50 kg and 100 kg BW, respectively), the experimental factors had a significant effect on the majority of behavior patterns in pigs. An increase in rest periods and a reduction in locomotor activity and other types of behavior were observed in older animals.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.

Thesis (M.Sc.) Uppsala : Sveriges lantbruksuniv.

O objetivo deste estudo foi avaliar a influência do número de leitões paridos e desmamados no primeiro parto, das reservas corporais ao parto e a perda das reservas corporais durante a lactação sobre a produção de leitões no segundo parto. Foram analisadas 1222 fêmeas que chegaram ao segundo parto sem interrupções como retorno ao estro, abortamento ou vazias ao parto. Foram medidos o peso corporal, espessura de toucinho (ET) e escore corporal visual (ECV), no máximo 24 horas pós-parto e no dia do desmame. Foram calculados a gordura e a proteína corporal ao parto e ao desmame para posteriormente serem obtidos os valores com relação às perdas destas reservas. O total de leitões nascidos no primeiro e no segundo partos e o número de leitões desmamados foram analisados de acordo com as características corporais e produtivas das fêmeas no primeiro parto e primeiro desmame. O tamanho de leitegada no primeiro e no segundo partos foram, respectivamente 12,4 leitões e o de 9,7 leitões nascidos totais. Na média as fêmeas apresentaram redução de 18,6 kg (9%) de peso corporal, 3,1mm de ET e 0,8 de ECV durante a lactação. O tamanho da leitegada no segundo parto não diferiu entre as classes das variáveis, peso, ET, ECV, gordura e proteína corporal no primeiro parto (P>0,05). As fêmeas com peso acima de 178kg, ET (≥16), ECV (≥3,0) e gordura corporal (≥21%) ao desmame tiveram maior leitegada no segundo parto e menor diferença no número de nascidos entre o primeiro e segundo parto (P<0,05). Fêmeas com maior percentual de proteína corporal ao desmame (≥15%) tiveram maior número de leitões nascidos na segunda leitegada. Houve maior diminuição no tamanho da segunda leitegada nas fêmeas com perdas de peso corporal acima de 10% (P<0,05). Perdas de proteína ou de gordura corporal acima de 10% e de 23%, respectivamente implicaram na maior diminuição no número de leitões nascidos no segundo parto (P<0,05). A perda de reservas corporais durante a lactação de primíparas influencia a redução do tamanho da leitegada no segundo parto. / The aim of this study was to evaluate the influence of body reserves at farrowing and the corporal reserves losses during the first lactation on the second litter size. A number of 1222 females that reached the second parity without interruptions as return to estrus, abortion or failing to farrow were analyzed. Measurements of body weight, backfat thickness (BT) and corporal condition (CC) were taken within 24-hours after farrowing and on the weaning day. Sow body fat and protein mass, at first farrowing and first weaning, were calculated and the values of these reserves losses were estimated. The total piglets at first and second farrowing and the number of weaned piglets were analyzed according to the females corporal and productive characteristics at first farrowing and first weaning.Litter size at first and second farrowing were respectively 12.4 and 9.7 total born piglets. In the average, the females demonstrated a reduction of 18.6 kg (9%) in body weight, 3.1mm BT and 0.8 CC during lactation. Second litter size did not differ between the categories body weight, BT, CC, body fat and body protein at first farrowing (P>0.05). Females with more than 178kg, BT (≥16), ECV (≥3.0) and body fat (≥21%) at weaning had largest second litters and less differences in the number of piglets born between first and second farrowing (P<0.05). Sow body protein mass at weaning (≥15%) had a higher effect on the number of piglets produced in the second litter. Females with weight losses during lactation above 10% showed the greatest reduction in second litter size (P<0.05). Protein or fat mass losses above 10% and 23%, respectively resulted in a high reduction in the number of total born piglets in second litter (P<0.05).Looses of corporal reserves during the first lactation influences the reduction in the second litter size.