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This thesis quantifies aspects of shade tolerance in tree seedlings of species native to the Caledonian pinewood ecosystems of Glen Affric (Highland Region, Inverness-shire). Growth, allocation and morphological responses of 15 species to irradiance under simulated forest canopy light were investigated in a nursery-based shade house experiment. The same responses of four of the 15 species (Ilex aquifolium, Alnus glutinosa, Sorbus aucuparia and Betula pubescens) to different developmental stages of Pinus sylvestris woodland were investigated in the field. The spatial and temporal growth responses of naturally regenerating S. aucuparia seedlings to shade and gap microhabitats were also studied. Data from the shade house experiment enabled further detailed exploration of the relationship between relative growth rates (RGR) and irradiance and potential cross-overs of ranks of growth in high and low light conditions.

Exotic species often invade new areas and displace native species. The problems associated with such invasions are well known, but for many exotic species, experimental work has not yet been done to predict which, and under what conditions they may become a problem. Two greenhouse experiments were devised to investigate the plasticity, shade tolerance, and phenotypic differences of full-siblings from 3 populations of Cardamine impatiens, a Eurasian species potentially invasive in North America. Potted plants were subjected to 0, 54, 76, or 91% shade created by neutral density shade cloth application. In addition, the impact of a cold pre-treatment of seedlings on the growth and reproductive output of C. impatiens plants was examined. In our first experiment, we subjected Cardamine impatiens to non-shaded cages, 54%, or 76% shade intensity. Plants died very quickly, so LD50 data were used as a relative measure of fitness, and relative growth indices were calculated over time. Other relative measures of fitness included canopy area, leaf area, number of leaves, number of leaves per canopy area, and final plant weight. Plants in cages with no shade treatment grew faster than those in cages with shade cloth and final plant weight decreased as shade treatment percentage increased. In each population, the number of leaves increased over time and the number of leaves per canopy area decreased over time under shade treatments. Our second experiment involved the application of 54%, 76%, and 91% shade intensity. The additional shade treatment of 91% was applied to determine the extent of plant tolerance and plasticity in response to light reduction. Due to high plant mortality in our first experiment, we treated Cardamine impatiens with a 4 week cold period prior to treatment, which simulates its biennial growth form in its natural western Virginia region habitat. Since this second experiment took place later in the year, day length was extended to more accurately duplicate the conditions during the first experiment. LD50 calculations were not necessary, and 7 of the 135 plants produced seed. Relative measures of fitness included canopy area, leaf area, number of leaves, number of leaves per canopy area, and final plant weights. As in experiment one, the number of leaves per plant increased over time, final plant weight decreased as shade treatment increased, and the number of leaves per canopy area decreased as shade treatment increased. From these two experiments, we determined that Cardamine impatiens is a species that exhibits phenotypic plasticity and therefore may pose a threat as an invasive species. C. impatiens is able to grow and exhibit plasticity of plant architecture under the conditions of very low light. The number of leaves per canopy area decreased as shade increased, suggesting that C. impatiens is highly adaptable to low light conditions, and therefore may be exhibiting phenotypic plasticity by reallocating its resources by producing fewer leaves while maintaining canopy area. This data along with other C. impatiens traits such as high levels needed for seed production, its persistence in seed banks, along with a lack of known major enemies, indicates that they have a great capacity to invade a wide variety of habitats. We also determined that a cold treatment is necessary in order for C. impatiens to obtain optimal growth and reproduction. / Master of Science

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Jack D. Fry / ‘Meyer’ zoysiagrass (Zoysia japonica Steud.) has been the predominant cultivar in the transition zone of the U.S. since its release in 1952, primarily because of its good freezing tolerance. However, it is slow to establish and recover after sod harvest, and has poor shade tolerance. I evaluated ‘Meyer’, some commonly used cultivars, and 18 progeny from crosses of ‘Emerald’ (Z. japonica × Z. tenuifolia Willd. ex Thiele) × Z. japonica or Z. matrella (L.) Merr. × Z. japonica for stolon growth characteristics; sod tensile strength and recovery after harvest; shade resistance; freezing tolerance and its relationship to autumn color retention; and the potential influence of dehydrin and chitinase gene expression in freezing tolerance. After planting vegetative plugs, rates of stolon initiation (r = 0.66 in 2007, r = 0.94 in 2008) and elongation (r = 0.66 in 2007, r = 0.53 in 2008) were positively correlated (P < 0.05) with zoysiagrass coverage. At 60 days after sod harvest, recovery growth coverage ranged from 17% to 97% and a progeny from Z. matrella × Meyer (97% coverage) demonstrated superior sod recovery growth to Meyer (38% coverage). Under 68% silver maple (Acer saccharinum L.) tree shade, stolon number was reduced 38 to 95% and stolon length 9 to 70% compared to turf in full sun. Several progeny from crosses between Emerald or a Z. matrella x Z. japonica produced more and/or longer stolons than Meyer in the shade, suggesting potential for increased shade tolerance. Autumn color in October and November, 2007 was positively correlated (r = 0.44 and r = 0.58, P < 0.01) with the lethal temperature killing 50% of tillers (LT50) in December, 2007. All grasses except Cavalier and one progeny were equivalent to Meyer in freezing tolerance with LT50s ranging from -0.2 to -12.2 oC. Dehydrin-like (11.9, 23, 44.3, and 66.3 kDa) and chitinase (26.9 kDa) gene expression increased with cold acclimation and was similar among all grasses. In general, some new zoysiagrass progeny exhibited superior growth and/or stress tolerances compared to Meyer, which bodes well for potential release of a new cultivar for use in the transition zone.

Desired forest conditions, or DFCs, are recently created parameters which strive to create diverse stands of hardwoods of various species and age classes, along with varying densities and canopy gaps, through the use of uneven-aged silvicultural methods and repeated stand entries. Little research has been conducted to examine residual stand composition and hardwood regeneration after DFC installment. The objectives of this study were to characterize forest overstory and midstory conditions after DFC treatments, assess the natural regeneration, and to characterize available light in the treatment and control areas. Residual stand conditions after application of DFC harvest guidelines indicate that shade tolerant species will be the future occupants of the sites and oaks will diminish or disappear over time. This documented initial forest response to DFC treatments can be used by forest and wildlife habitat managers when assessing the potential outcomes of DFC management.

Western larch (Larix occidentalis Nutt.) is an important component of the montane forest in southeastern British Columbia. It grows in cool-temperate (IDF and ICH zones) and boreal climates (MS zone and, occasionally, ESSF zone). Larch is considered a very shade-intolerant species which can tolerate low light (partial shading) only during the seedling stage (the first 5 growing seasons). Typically, it regenerates after fire in the open on seedbeds exposed by burning. However, to what extent it tolerates low light and how various light environments affect its survival and growth is not known. The objective of our study was to determine the variation in survival and growth of western larch seedlings in relation to light availability and site conditions.

The world is progressing towards a more sustainable society, where renewable energy sources, including solar energy, play a crucial role. This study aims to address the conflict between agriculture and energy production by exploring the installation of solar panels on farmland. Four scenarios are considered, with varying parameters such as latitude, azimuth, slope, and row distance between photovoltaic (PV) modules. The study focuses on two different crops, lettuce and potato, which have varying tolerances to shading. The objective is to understand how the shadows cast by solar panels affect the growth of these crops. To analyze the impact of shading, the PVsyst software program is utilized to obtain PAR values for each scenario. The calculations are performed using Excel equations. The literature review encompasses scientific sources that provide insights into both PV technology and agriculture, bolstering the research findings. To ensure realism and manage simulation time, certain delimitations were made. These include limiting the study to two cities in Sweden, comparing only two crops, and conducting simulations during the summer period. The results reveal a significant potential for growing potatoes under PV modules. However, lettuce faces difficulties due to its high requirement for solar intensity (PAR), making it less adaptable to shade. The findings of this study indicate that crops like potatoes, which have a lower requirement for PAR, can be successfully cultivated in conjunction with photovoltaic (PV) systems. However, it is not advisable to implement AV systems in areas where sensitive crops like lettuce, which necessitate a significant number of sun hours with high solar intensity.

Orientador: Massanori Takaki / Banca: Victor José Mendes Cardoso / Banca: Sergius Gandolfi / Banca: Débora Leonardo dos Santos / Banca: Dalva Maria Silva Matos / Resumo: As espécies invasoras são reconhecidas como um dos mais importantes e difíceis fatores que influenciam a conservação dos ecossistemas nativos. Na restauração de ambientes degradados, estas espécies podem afetar profundamente a trajetória do recobrimento vegetal pelas espécies nativas e, conseqüentemente, a composição do ecossistema. Um fator importante para o sucesso de algumas espécies vegetais invasoras é a plasticidade fenotípica, dandolhes grande capacidade de aclimatação em diversas condições ambientais. O conhecimento dos fatores ambientais e das características da planta que contribuem para o sucesso das espécies invasoras é de grande importância para predizer a habilidade de invasão e para esforços de manejo. Neste contexto, o objetivo principal deste estudo foi conhecer algumas características fisiológicas e ecológicas de Clausena excavata Burm. f., uma espécie de árvore exótica reconhecida como invasora em algumas regiões no mundo, no intuito de compreender o sucesso da espécie como invasora e contribuir com informações relevantes para possíveis tentativas de controle. Primeiramente, foram avaliados os efeitos da luz e da temperatura em sua germinação (condição controlada) e o efeito da luz na emergência de suas plântulas (condição natural, a pleno sol e sob a copa das árvores). As sementes germinaram tanto na presença como na ausência de luz, nas temperaturas de 20 a 35°C, sem diferença entre a porcentagem de sementes germinadas nas diferentes temperaturas. Sementes mantidas a 20°C, em ambas as condições de luz, germinaram mais lentamente em relação às demais temperaturas. Independente da temperatura, na presença de luz as sementes apresentaram uma germinação muito mais sincronizada do que aquelas mantidas no escuro. Tais resultados mostraram que as sementes de C. excavata são fotoblásticas neutra. Em campo, a emergência... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The invasive species are recognized one of more important and difficult factors that prejudice the conservation of native ecosystems. In the restoration of degraded environment, these species can to affect profoundly the trajectory of recovery by native species and, therefore, the ecosystems composition. An important factor to the success of invasive species is their phenotypic plasticity, which gives them a great ability to adjust in several environmental conditions. The knowledge of environmental factors and plant characteristics that contribute to the success of invasive species is very important to predict the invasion capacity and to manage efforts. In this context, the main objective of this study was to know some physiological and ecological characteristics of Clausena excavata Burm. f., a nonnative tree species recognized as invasive somewhere of the world, with intention to understand the success of this species as invasive and to contribute with relevant informations for a possible management. At first, were evaluated the effects of light and temperature on their seeds germination (controlled condition) and the effect of light on seedling emergence (natural condition, at full sun and shade). The seeds germinated in presence and absence of light, from 20 to 35°C, without difference among the germination percentage at different temperatures. Seeds maintained in 20°C, at both light conditions, germinated slowly than others temperatures. Independent of temperature, in light the seeds showed a germination more synchronized than the seeds kept in darkness. Those results showed that C. excavata have neuter photoblasics seeds. On the field, the emergence occurred at both environments, but at full sun all seeds produced a seedling. The seedling emergence occurred with same rate and synchronization index on two tested conditions. Thereafter, the seedlings were observed with purpose... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-06-11T19:30:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-06Bitstream added on 2014-06-13T19:40:38Z : No. of bitstreams: 1 vieira_dcm_dr_rcla.pdf: 661675 bytes, checksum: 027c5de7e016fd68cc667e08fc20b57d (MD5) / As espécies invasoras são reconhecidas como um dos mais importantes e difíceis fatores que influenciam a conservação dos ecossistemas nativos. Na restauração de ambientes degradados, estas espécies podem afetar profundamente a trajetória do recobrimento vegetal pelas espécies nativas e, conseqüentemente, a composição do ecossistema. Um fator importante para o sucesso de algumas espécies vegetais invasoras é a plasticidade fenotípica, dandolhes grande capacidade de aclimatação em diversas condições ambientais. O conhecimento dos fatores ambientais e das características da planta que contribuem para o sucesso das espécies invasoras é de grande importância para predizer a habilidade de invasão e para esforços de manejo. Neste contexto, o objetivo principal deste estudo foi conhecer algumas características fisiológicas e ecológicas de Clausena excavata Burm. f., uma espécie de árvore exótica reconhecida como invasora em algumas regiões no mundo, no intuito de compreender o sucesso da espécie como invasora e contribuir com informações relevantes para possíveis tentativas de controle. Primeiramente, foram avaliados os efeitos da luz e da temperatura em sua germinação (condição controlada) e o efeito da luz na emergência de suas plântulas (condição natural, a pleno sol e sob a copa das árvores). As sementes germinaram tanto na presença como na ausência de luz, nas temperaturas de 20 a 35°C, sem diferença entre a porcentagem de sementes germinadas nas diferentes temperaturas. Sementes mantidas a 20°C, em ambas as condições de luz, germinaram mais lentamente em relação às demais temperaturas. Independente da temperatura, na presença de luz as sementes apresentaram uma germinação muito mais sincronizada do que aquelas mantidas no escuro. Tais resultados mostraram que as sementes de C. excavata são fotoblásticas neutra. Em campo, a emergência... / The invasive species are recognized one of more important and difficult factors that prejudice the conservation of native ecosystems. In the restoration of degraded environment, these species can to affect profoundly the trajectory of recovery by native species and, therefore, the ecosystems composition. An important factor to the success of invasive species is their phenotypic plasticity, which gives them a great ability to adjust in several environmental conditions. The knowledge of environmental factors and plant characteristics that contribute to the success of invasive species is very important to predict the invasion capacity and to manage efforts. In this context, the main objective of this study was to know some physiological and ecological characteristics of Clausena excavata Burm. f., a nonnative tree species recognized as invasive somewhere of the world, with intention to understand the success of this species as invasive and to contribute with relevant informations for a possible management. At first, were evaluated the effects of light and temperature on their seeds germination (controlled condition) and the effect of light on seedling emergence (natural condition, at full sun and shade). The seeds germinated in presence and absence of light, from 20 to 35°C, without difference among the germination percentage at different temperatures. Seeds maintained in 20°C, at both light conditions, germinated slowly than others temperatures. Independent of temperature, in light the seeds showed a germination more synchronized than the seeds kept in darkness. Those results showed that C. excavata have neuter photoblasics seeds. On the field, the emergence occurred at both environments, but at full sun all seeds produced a seedling. The seedling emergence occurred with same rate and synchronization index on two tested conditions. Thereafter, the seedlings were observed with purpose... (Complete abstract click electronic access below)