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No description available.

No description available.

The thesis examines land-use changes in a selected area of the Niagara Fruit Belt between 1954 and 1978. Part of the former township of Louth was chosen for investigation because it is located in the centre of the fruit belt, and is an area affected by several urban influences. Two detailed land-use maps were produced from aerial photograph interpretation. These maps reveal the many exchanges among agricultural land uses and the actual loss to urban and urban-related uses which occurred during the time span investigated. They indicate the loss of fruit land to non-agricultural uses is less than was anticipated. Increases in grape acreages have been implemented relatively close to the city of St. Catharines and the lost peach acreage is not entirely due to urbanization. A land-use change index was developed, based on total change per lot, for use in the quantitative analysis. The 1954 assessment roll provided the data on individual properties. Eight hypotheses were developed to account for the land-use changes. These were rejected, and it was suggested that the study area was undergoing a "normal” process of change, resulting from a combination of agricultural and urban forces. Further research is needed in order to understand more fully, the processes of land-use change in an area such as Louth. / Thesis / Master of Science (MS)

Many land systems experience massive ecological pressure due to ongoing land use changes for the increasing demand for food, but also need to sustain essential ecosystem services. Computer-based model scenarios help to anticipate the consequences of different socio-economic future transition pathways for humans and nature and evaluate trade-offs between various demands on land. In many grassland ecosystems, the processes of agricultural abandonment in less attractive regions coexist with agricultural intensification in others. At the same time, the ecological value of natural grassland is rarely considered in decision making. By using the CLUMondo land use modelling framework I mapped the future composition of the land system of Orenburg province under five socio-economic scenarios with different ranges of food production intensification. The outcomes allowed me to identify hotspot areas for arable land expansion, grassland restoration, and agricultural abandonment. Most agricultural expansion is prevalent in three scenarios with high ambition for food production, and, without active policy interventions, some natural grassland areas in northern parts of the province are likely to be converted to cropland. In a scenario with low demand for food production, large areas in southern parts could be abandoned creating good opportunities for grassland restoration on former cropland, but possibly having negative socio-economic consequences, such as people’s migration to northern parts of the province. In a scenario with lesser ambition for crop production, but an increase in meat production, agricultural abandonment is less widespread and will even include some additional conversion of cropland to pasture. With appropriate policies aimed at supporting sustainable grazing practices (together with favourable global socio-economic conditions), such scenario can provide an opportunity for satisfying demands for food, providing livelihoods, and ensuring the flow of ecosystem services by grassland ecosystems.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Forests in South Africa have had a long history of human utilization and disturbance, and are under threat from a variety of anthropogenic land use changes. Foremost of these are deforestation and forest degradation, impacting the species native to these forests. The aims of this study were to determine changes in the distribution of forest dependent bird species according to the South African Bird Atlas Project; to relate these changes to changes in land-use; to identify links between these changes; to determine the extent, location and causes of the decline of each forest dependent bird species; and to identify current risks to forest dependent bird species in South Africa. Range data on 57 forest dependent bird species from SABAP1 (1987-1992) and SABAP2 (2007-present) were analyzed. Of these, 28 species were found to have declining ranges. Thirty sites across South Africa were identified as being most at risk, with all having experienced a loss of more than 10 of the 57 forest dependent bird species between SABAP1 and SABAP2. The range change data of the 28 species with decreasing ranges were correlated with data on changes in land cover over the same time period to infer relationships between changes in land use and change in bird ranges. Occupancy modelling was done to determine which land cover types affect extinction and initial presence. Individual species characteristics were analyzed to determine links between characteristics and response to land use change. A pan-European trait-based risk assessment framework was applied to all 57 species to identify habitats and species most at risk, as well as the most important threats to species persistence. Results showed that natural vegetation decreased in 67% of sites, while plantations and cultivation increased in 50% of sites. Occupancy modelling showed extinction likelihood to increase with plantations in some species, while plantations mitigated extinction likelihood in other species. Urbanization and cultivation likewise mitigated extinction likelihood in some species. Natural vegetation was replaced by cultivation, while cultivation was replaced by urbanization. The number of species lost increased with a loss of natural vegetation. Twenty two of the thirty sites experienced deforestation of indigenous forests between 2000 and 2013/2014; changes in natural vegetation in these sites can be attributed primarily to deforestation, and a loss of plantations. While most at-risk sites were in the Eastern Cape, there was no geographic grouping of species loss or of land use change. Most species lost were birds of prey or insectivores, and species characteristics and habitat preferences determined the sites from which they were lost. The Cape parrot (Poicephalus robustus), rufous-chested sparrowhawk (Accipiter rufiventris) and the migratory Eurasian golden oriole (Oriolus oriolus) suffered the largest declines in range size and are thought to be most at risk. Montane forests were found to be more at risk than other forest types. The major risks facing montane forests were increased abundance of small predators, increased fire suppression, increased soil management, removal of deadwood and reduced diversity of tree species. These threats are all products of plantation forestry and local harvesting. Nesting risk was higher than foraging risk for all species, indicating that nesting habitat should be better preserved. Half of South Africa’s forest dependent bird species have declining ranges, with the loss of these species most prominent in the Eastern Cape. Natural vegetation loss, comprising mostly recent deforestation; increased cultivation and urbanization; and changes in plantation cover are thought to be the main factors determining these declines. Montane forests in particular should be better protected to preserve forest dependent species, and the negative effects of plantation forestry and local harvesting should be mitigated. / AFRIKAANSE OPSOMMING: Suid-Afrika het ‘n lang geskiedenis van woude wat deur mense gebruik, asook vernietig word. Woude word bedreig deur verskeie menslike grondgebruike en veranderinge. Die mees vooraanstaande van die bedreigings is ontbossing en woud verdunning, wat ‘n invloed het op inheemse spesies in die woude. Die doelwitte van hierdie studie was om veranderinge in die verspreiding van bos-afhanklike voëlspesies vas te stel volgens die Suid Afrikaanse Voël Atlas Projek; om hierdie veranderinge te verband met veranderinge in grondgebruik; om verbande tussen hierdie veranderinge te identifiseer; om die mate, die plek en die oorsake van die agteruitgang van elke bos-afhanklike voëlspesies te bepaal; en om huidige risiko's aan die bos afhanklik voëlspesies in Suid-Afrika te identifiseer. Trefwydte inligting oor 57 woud afhanklike voëlspesies van SABAP1 (1987-1992) en SABAP2 (2007-nou) was geanaliseer. Daar was gevind dat vanuit die spesies, het 28 ‘n afneming in trefwydte ervaar. Dertig terreine in Suid-Afrika was uitgeken as dié met die hoogste risiko, met ‘n verlies van meer as 10 van die 57 woud afhanklike voëlspesies tussen SABAP1 en SABAP2. Die trefwydte inligting van die 28 spesies met ‘n afnemende trefwydte was gekorreleer met inligting oor veranderinge in grond bedekking oor dieselfde tydperk om verhoudings tussen veranderinge in grond gebruik en veranderinge in voël trefwydtes aftelei. Besetting modellering was gedoen om te bepaal watter tipes grond bedekking beinvloed uitwissing en aanvanklike teenwoordigheid. Kenmerke van individuele spesies is ontleed om verbande tussen kenmerke en reaksie op verandering in grondgebruik te bepaal. ‘n Pan-Europese eienskap gebaseerde risiko-analise raamwerk is toegepas op die 57 spesies om die spesies en habitatte met die grootse risiko te identifiseer, asook die belangrikste bedreigings vir spesies-volharding. Die resultate het gewys dat natuurlike plantegroei het verminder in 67% van terreine, terwyl plantasie en verbouing vermeerder het in 50% van terreine. Besetting-modellering het gewys dat waarskynlikheid van uitwissing vermeerder met plantasies in sommige spesies, terwyl plantasies die waarskynlikheid van uitwissing verminder het in ander spesies. Verstedeliking en verbouing het ook die waarskynlikheid van uitwissing verminder in sommige spesies. Natuurlike plantegroei was vervang deur verbouing, terwyl verbouing vervang is deur verstedeliking. Die aantal spesies verlies het vermeerder met die vermindering van natuurlike plantegroei. Twee en twintig van die dertig terreine het ontbossing van inheemse woude ervaar tussen 2000 en 2013/2014. Veranderinge in natuurlike plantegroei in die terreine is meestal as gevolg van ontbossing, en ‘n vermindering van plantasies. Terwyl meeste van die hoë risiko terreine in die Oos-Kaap was, was daar geen geografiese groepering van spesies vermindering of grondgebruik veranderinge nie. Meeste spesies wat vernietig is was roofvoëls of insectivore, en spesies kenmerke en habitat voorkeure het die terreine bepaal waaruit hulle verloor is. Die grootpapegaai (Poicephalus robustus), rooiborssperwer (Accipiter rufiventris) en die trekvoël Europese wielewaal (Oriolus oriolus) het die grootste vermindering in trefwydte grootte ervaar, en is vermoedelik die grootste risiko. Bergwoude was gevind om meer in gevaar te wees as ander woud tipes. Die grootste risikos wat bergwoude beïnvloed het was ‘n toenemende hoeveelheid klein roofdiere, verhoogde vuur onderdrukking, verhoogde grondbestuur, verwydering van dooie hout, en verlaagde diversiteit van boomspesies. Hierdie bedreigings is almal as gevolg van plantasie bosbou en plaaslike oes. Nes-risiko was hoër as kos soek risiko vir alle spesies, wat aandui dat nes-habitat beter bewaar moet word. Die helfte van Suid-Afrika se woud-afhanklike-voëlspesies het dalende trefwydtes, met die verlies van hierdie spesies mees opvallend in die Oos-Kaap. Die verlies van natuurlike plantegroei, as gevolg van onlangse ontbossing; verhoogde verbouing en verstedeliking; en veranderinge in plantasie bedekking is vermoedelik die hooffaktore wat die vermindering van voëlspesies veroorsaak. Veral bergwoude moet beter beskerm word om woud-afhanklike-voëlspesies te bewaar en die negatiewe invloede van plantasiebosbou en plaaslike oes te verminder.

The management of New Zealand’s freshwater resources has come under increasing pressure from different industrial and environmental stakeholders. Land use change and the pressure it can put on water resources has been a significant issue regarding resource management in New Zealand. A significant mechanism driving land use change has been the growth of forestry, dairy farming, and other agricultural industries. Improvements in agricultural and forestry science and irrigation techniques have allowed new, previously less arable areas of New Zealand to be subject to land use change, such as the conversion of tussock grassland to pasture in steep, mountainous regions in the South Island. Studies regarding the effects of land use change in such catchments, especially with focus on flood hydrology, appear to be limited, despite the importance of managing catchment headwaters to minimise flood risk downstream. The TopNet model was used in this research project to evaluate the potential effects of land use change on flood hydrology in mountain catchments. It is a semi-distributed continuous rainfall-runoff model developed by the National Institute of Water and Atmospheric Research (NIWA). It has been widely used in New Zealand, and applications have included modelling water yield and the effect of climate change in catchment networks. However, it was not developed specifically for predicting flood flows. Hence, testing the model for flood peak prediction in mountainous catchments was also performed, and may show that TopNet can be a useful tool in resource management in New Zealand. The Ahuriri and Pelorus River catchments were used in this investigation. Both are steep catchments located in the South Island. The Ahuriri River catchment, in the Waitaki Basin on the eastern side of the Southern Alps, is a semi-arid catchment dominated by tussock grassland. The surrounding catchments are heavily influenced by infrastructure for hydroelectric power (HEP) generation and more recently irrigation for dairy farming. The Pelorus River catchment is located at the northern end of the South Island. It is primarily covered in native forest, but adjacent catchments are subject to agricultural and forestry development. The ability of the TopNet model for each catchment to predict flood flows were tested using a selection of historical flood events. Rainfall input to the model was at a daily timestep from the virtual climate station network (VCSN), and the method of disaggregating the daily estimate into an hourly rainfall series to be used by the model was found to have a significant influence on flood prediction. Where an accurate historical rainfall record was provided from a rainfall gauge station within the catchments, the disaggregation of the daily rainfall estimate based on the station data produced a significantly more accurate flood prediction when compared to predictions made using a stochastic disaggregation of the daily rainfall estimate. The TopNet models were modified to reflect land use change scenarios: the conversion of tussock grassland to pasture and the afforestation of tussock in the Ahuriri River catchment, and the conversion of forested land to pasture and the harvest of plantation forestry in the Pelorus River catchment. Following a past study into modelling the effects of land use change using TopNet, three key model parameters were modified to reflect each land use scenario: saturated hydraulic conductivity KS, canopy storage capacity, and the canopy enhancement factor. Past studies suggested a wide range of suitable values for KS, although also acknowledged that KS depends heavily on the specific catchment characteristics. A sensitivity analysis showed that KS had a significant influence on flood peak prediction in TopNet. It is recommended that further investigation be conducted into suitable values for KS. TopNet appeared to predict the effect of land use change on flood magnitude in mountainous catchments conservatively. Past studies of land use change suggested that the effect on flood flows should be significant, whereas TopNet generally predicted small changes in flood peaks for the scenarios in each catchment. However, this may suggest that the topography, geology, and soil properties of steep catchments are more important to flood hydrology than land cover. Further investigation into the effect of such catchment characteristics is recommended. Nevertheless, TopNet was shown to have the potential to be a useful tool for evaluating and managing the effects of land use change on the flood hydrology of mountainous catchments in New Zealand.

No description available.

Alterations to the land surface can be attributed to both human activity and natural variability. Human activities, such as urbanization and irrigation, can change the conditions of the land surface by altering albedo, soil moisture, aerodynamic roughness length, the partitioning of net radiation into sensible and latent heat, and other surface characteristics. On the other hand, natural variability, manifested through changes in atmospheric circulation, can also induce land surface changes. These regional scale land surface changes, induced either by humans or natural variability, can effectively modify atmospheric conditions through land-atmosphere interactions. However, only in recent decades have numerical models begun to include representations of the critical processes driving changes at the land surface, and their associated effects on the overlying atmosphere. In this work we explore three mechanisms by which changes to the land surface–both anthropogenic and naturally induced–impact the overlying atmosphere and affect regional hydroclimate. The first land-atmosphere interaction mechanism explored here is land-use and land-cover change (LULCC) due to urban expansion. Such changes alter the surface albedo, heat capacity, and thermal conductivity of the surface. Consequently, the energy balance in urban regions is different from that of natural surfaces. To evaluate the changes in regional hydroclimate that could arise due to projected urbanization in the Phoenix–Tucson corridor, Arizona, my first study applied the Weather Research and Forecasting (WRF) with an Urban Canopy Model (UCM; which includes a detailed urban radiation scheme) coupled to the Noah land surface model to this region. Land-cover changes were represented using land-cover data for 2005 and projections to 2050, and historical North American Regional Reanalysis (NARR) data were used to specify the lateral boundary conditions. Results suggest that temperature changes are well defined, reflecting the urban heat island (UHI) effect within areas experiencing LULCC, whereas changes in precipitation are less certain (statistically less robust). However, the study indicates the likelihood of reductions in precipitation over the mountainous regions northeast of Phoenix and decreased evening precipitation over the newly urbanized area. The second land-atmosphere interaction mechanism explored here is irrigation which, while being an important anthropogenic factor affecting the local to regional water cycle, is not typically represented in regional climate models. In this (second) study, I incorporated an irrigation scheme into the Noah land surface scheme coupled to the WRF model. Using a newly developed water vapor tracer package (developed by Miguez-Macho et al. 2013), the study tracks the path of water vapor that evapotranspires from the irrigated regions. To assess the impact of irrigation over the California Central Valley (CCV) on the regional climate of the U.S. Southwest, I ran six simulations (for three dry and three wet years), both with and without the irrigation scheme. Incorporation of the irrigation scheme resulted in simulated surface air temperature and humidity that were closer to observations, decreased the depth of the planetary boundary layer over the CCV, and increased the convective available potential energy. The results indicated an overall increase in precipitation over the Sierra Nevada Range and the Colorado River Basin during the summer, with water vapor rising from the irrigated region moving mainly northeastward and contributing to precipitation in Nevada and Idaho. The results also indicate an increase in precipitation on the windward side of the Sierra Nevada Range and over the Colorado River Basin. The former is possibly linked to a sea-breeze type circulation near the CCV, while the latter is likely associated with a wave pattern related to latent heat release over the moisture transport belt. In the third study, I investigated the role of large-scale and local-scale processes associated with heat waves using the Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and evaluate the performance of the regional climate model ensemble used in the North America Regional Climate Change Program (NARCCAP) in reproducing these processes. The Continental US is divided into different climate divisions (following the convention of the National Climate Assessment) to investigate different mechanisms associated with heat waves. At the large scale, warm air advection from terrestrial sources is a driving factor for heat waves in the Northeast and Midwest. Over the western United States, reduced maritime cool air advection results in local warming. At the local scale, an antecedent precipitation deficit leads to the continuous drying of soil moisture, more energy being partitioned into sensible heat flux and acting to warm surface air temperatures, especially over the Great Plains. My analysis indicates that the NARCCAP simulated large-scale meteorological patterns and temporal evolution of antecedent local-scale terrestrial conditions are very similar to those of MERRA. However, NARCCAP overestimates the magnitude and underestimates the frequency of Northeastern and Midwestern US heat waves, partially due to anomalous heat advection through large-scale forcing. Overall, the aforementioned studies show that utilization of new parameterizations in land surface models, such as the urban canopy scheme and the irrigation scheme, allow us to understand the detailed physical mechanisms by which anthropogenic changes in the land surface can affect regional hydroclimate, and may thus help with informed decision making and climate adaptation/mitigation. In addition to anthropogenic changes of the land surface, humans are of course affecting the overlying atmosphere. Currently, NARCCAP is the best available tool we have to help us understand the effects of changes greenhouse gas induced climate change at the regional scale. The regional climate models participating in NARCCAP are able to realistically represent the dominant processes associated with heat waves, including the atmospheric circulation changes and the land-atmosphere interactions that drive heat waves. This lends credibility, when analyzing the projections of these models with increased GHG emissions, to the assessment of changes in heat waves under a future climate.