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1
Agha, N. S. A. "High-density planting system for Bramley's seedling apple trees." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373464.
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Boe, Brian Jeffrey Dickson Kenneth L. "Evaluating tree seedling survival and growth in a bottomland old-field site implications for ecological restoration /." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3998.
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Sheeter, Eric. "Mechanical silviculture." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/10527.
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Problem: How to mechanise tree planting in North American logged sites? Trees are presently hand planted. Preliminary exploration identified the following collection of sub-problems. Vehicle: How to carry tools reliably and cost effectively over rough obstacle strewn ground? Results: U.S.A. - patent granted European Patent Office - patent granted Canada - patent granted The patents cover the main form and mode of operation of a simple but unconventional vehicle. Silvicultural/mechanical: How to mechanise the handling and placement of trees? Results: Two International Patents allowed. They cover a magazine/feed mechanism and a placement mechanism. They form a planting tool. One man guides the vehicle/tool system. An array of planting tools is carried. Two problems arise from the need to make guidance manageable and the planting rate fast enough. Spacing: How to cause the members of a collection of simultaneously operating tools to space themselves appropriately the spacing being driven by machine perceived cues? Choice: How to cause a tool to move to and halt over a plan table spot, tool action being driven by machine perceived cues? Results: One International Patent allowed. Spacing: A conceptual solution is described. Choice: A semi-automatic solution is described. It involves a system of tool guidance and a system of tool set-up, both light guided. Two methods for the detection of light signals in the presence of sunlight have been investigated. Choice-automatic; two solutions have been explored. One uses standard data processing, the other "parallel" processing. Here an idealised device is described which will compare for likeness two two-dimensional patterns.
4
Doust, Susan Jillian. "Seed and seedling ecology in the early stages of rainforest restoration /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18410.pdf.
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Lhotka, John Michael Loewenstein Edward F. "Predicting light transmittance and seedling growth across a gradient of riparian forest canopy structures." Auburn, Ala., 2006. http://hdl.handle.net/10415/1315.
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Bertin, Sophie. "Physiological ecology of understorey trees in low impact silvicultural systems." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3773.
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Continuous cover forestry (CCF), an alternative forest management approach to clearfelling, is increasingly being adopted in the UK. It aims at enhancing stand structural diversity and favouring natural regeneration and subsequent seedling growth below the existing canopy of plantation forests. One area of limited knowledge is the critical level of below-canopy light for the growth of naturally regenerating seedlings. In addition, plant growth beneath canopies is influenced by other factors (e.g. herbivory). Picea sitchensis (Bong.) Carr. (Sitka spruce) seedlings under canopies have been observed to be severely damaged by Elatobium abietinum (Walker) (green spruce aphid) attacks. The combined effects of light availability and insect attack on seedling growth are not well understood, however, this understanding is crucial in order to ensure successful management of regeneration within CCF systems. A controlled experiment, which mimicked different natural understorey light levels along with repeated artificial aphid infestation, was conducted over two years to look at seedling performance through structural and physiological (chlorophyll fluorescence) measurements. Aphid population assessments showed significant increased population density under shaded conditions. Nevertheless, aphid impacts were mainly localised in extent while the impact of light was the major component that described seedling growth. Light was the primary factor affecting the whole-plant biomass, whereas aphids had only localised effects on the total dry weight of older needles and roots, and on leader extension growth. A significant interaction between light levels and presence/absence of aphid infestation was found for main leader extension growth of the seedlings during the second year of the experiment, with lower values at low light levels under infestation. Plant biomass allocation was affected strongly by light, while aphid presence did not result in significant changes. At the leaf physiologylevel, the light environment was found to be the main driving factor affecting photosynthetic response, whilst aphid presence had only a short-term localised effect on photosynthesis. The impact of light levels and aphid presence on seedling growth were also determined at an experimental field site where plots were located across two light regimes typical of CCF conditions in upland UK coniferous forests. The comparison of the photosynthetic response of the seedlings in both the controlled and field experiment highlighted the importance of considering the temporal heterogeneity of the light environment experienced by understorey seedlings in CCF stands, while aphid and aphid x light interaction effects could not be determined due to very low aphid levels during the year. Finally, a pre-existing light model was parameterised to predict the understorey light environment required to promote successful seedling growth in CCF stands. Sensitivity and validation analyses were also performed.
7
Van, Etten Erica. "Seedling recruitment of large-seeded tropical trees planted as seeds in the Ecuadorian Amazon." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025046.
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Boe, Brian Jeffrey. "Evaluating Tree Seedling Survival and Growth in a Bottomland Old-field Site: Implications for Ecological Restoration." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3998/.
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In order to assess the enhancement of seedling survival and growth during drought conditions, five-hundred bare-root seedlings each of Shumard oak (Quercus shumardii Buckl.) and green ash (Fraxinus pennsylvanica Marsh.) were planted each with four soil amendments at a Wildlife Management Area in Lewisville, Texas. The treatments were a mycorrhizal inoculant, mulch fabric, and two superabsorbent gels (TerraSorb® and DRiWATER®). Survival and growth measurements were assessed periodically for two years. Research was conducted on vegetation, soil, and site history for baseline data. Both superabsorbent gels gave significant results for Shumard oak survival, and one increased green ash diameter. For overall growth, significant results were found among DRiWATER®, mycorrhizae, and mulch treatments.
9
El-Hodairi, M. H. "Chemical and physical methods of controlling the growth and stimulating the precocity of Bramley's seedling apple trees." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376249.
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Albro, Sandra Leigh. "Effects of Canopy Adult Trees on Seedling Recruitment of American Beech and Sugar Maple in Fragmented Forests." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238695571.
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Holgén, Per. "Seedling performance, shelter tree increment and recreation values in boreal shelterwood stands /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5854-4.pdf.
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Eck, Jenalle L. "Variation in Tropical Tree Seedling Survival, Growth, and Colonization by Arbuscular Mycorrhizal Fungi near Conspecific Adults: Field and Shadehouse Experiments in Panama." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503242529467534.
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Marks, Christian O. "The evolution of functional diversity in tree seedlings /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100651.
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This dissertation examined the participation of eight lower-achieving readers in two intermediate-level elementary classrooms (one fourth- and one fifth-grade) during group discussions about literary texts. The purpose of the investigation was to determine the extent to which lower-achieving readers (defined as students who had persistent struggles to attain minimum scores on state, district, and classroom assessments in reading) displayed discourse features that indicated the students' high-level thinking during heterogeneous and homogeneous (by reading level) discussions about literary texts. Several characteristics of discourse indicate high-level thinking, including but not limited to: generalizations, analyses, speculations, affective responses, inter-textual connections, and elaborated explanations. A secondary purpose was to describe what happened when lower-achieving readers, their peers, and teachers engaged in group discussions about text.<br>A multiple case study design was used in this investigation. Data were collected between October 2005 and May 2006. Data sources included: field notes collected from participant observation, transcripts and indices of student and teacher interviews, transcripts and indices of audiotaped and videotaped discussions and reading lessons, and students' writing assignments and other artifacts. Multiple strategies were used to analyze the data, including analytic induction and descriptive statistical techniques. A discourse analysis coding scheme was used to determine the extent to which lower-achieving readers likely used high-level thinking about literary texts during group discussions.<br>The findings revealed focal students used the discourse of discussion as a tool to comprehend text in two ways. The students used the discourse about texts as intellectual scaffolds for their own thinking and transformation in understanding of the texts. In addition, the discussions created authentic opportunities for students to explore reading comprehension strategies (e.g., meanings of new words, visualizing the story). This means students drew on their knowledge of comprehension strategies and incorporated them into their discussions to reason about the texts without explicit instruction from the teacher. Focal students both evoked and heard others refer to and talk about the comprehension strategies during discussions. Moreover, an important contextual foundation of the discussions that seemed to relate to the focal students' thoughtful responses, or those that suggested the students went beyond recalling the literal details of the stories, was the use of the discourse to problem-solve about the meaning of the texts. Finally, in respect to the students' writing assignments that often followed the discussions about the texts, lower-achieving readers made use of the ideas of the discussions in their writing.<br>Regarding high-level thinking during discussions, the lower-achieving readers' discourse suggested that they thought in high-level ways about texts during discussions, and that they thought in high-level ways to the same extent or nearly the same extent as their peers did in the same discussions about texts. The one major difference in their talk about texts related to the instances of elaborated explanations or instances when students stated a position and explained their thoughts about the position with more than one reason or with evidence from the text. Higher-achieving readers produced significantly more 'elaborated explanations' during discussions than the lower-achieving readers in this study.<br>From a theoretical perspective, this investigation extends our understanding of lower-achieving readers' use of discursive practices that influence thinking and reasoning about text. From pedagogical perspectives, the findings suggest teachers might need to understand ways to encourage a kind of discourse that elicits genuine problem-solving about the meanings of text. Likewise, teachers might need to understand the discourse features that indicate high-level thinking to model and discuss the features in their work with lower-achieving readers during discussions about literary texts.
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Paine, C. E. Timothy. "Ecological factors affecting the diversity of tropical tree seedlings /." View online, 2007. http://etd.lsu.edu/docs/available/etd-06272007-084024/unrestricted/CETP_diss_2007_06_21.pdf.
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Thesis (Ph. D.)--Louisiana State University, Baton Rouge, 2007.<br>Includes bibliographical references (p. 89-106). Also available via the World Wide Web: http://etd.lsu.edu/docs/available/etd-06272007-084024/unrestricted/CETP_diss_2007_06_21.pdf
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Lucas, Maree Eleanor. "Allocation in tree seedlings." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/12482.
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The hypothesis that allocation between the main tree components is controlled by the relative uptake rates of carbon dioxide and nutrient was tested by growing one-year-old sycamore seedlings (<I>Acer pseudoplatanus</I> L.) at elevated and ambient CO<SUB>2</SUB> concentrations and at two nutrient addition rates which were modelled in accordance with a predicted optimal growth function. Elevated CO<SUB>2</SUB> concentration significantly increased the leaf dry mass but did not significantly change the dry mass of any other component. In contrast nutrient addition rate had large effects on all biomass components with the exception of the root. Allocation was strongly affected by nutrient addition rate although CO<SUB>2</SUB> treatment only affected the allocation to the stem. Nutrient concentrations were reduced by growth at elevated CO<SUB>2</SUB> concentrations. Leaf starch concentrations were larger at elevated CO<SUB>2</SUB> concentrations. There were no differences in soluble leaf carbohydrate concentrations between treatments. There was evidence of downregulation of photosynthesis at the low nutrient addition rate but not at elevated CO<SUB>2</SUB> concentrations. In conclusion, the growth concentration of CO<SUB>2</SUB> and nutrient and water availabilities are important in the control of allocation. Increases in atmospheric CO<SUB>2</SUB> concentrations are likely to be accompanied by shifts in allocation towards the root and stem although the magnitude of these changes will be determined by the nutrient availability of soils. The effects of perturbations in these variables are also determined by differences in growth and allocation between clones of the same species, between species and by the development of allocation patterns which are dependent on phenology. The functional balance is useful in predicting changes in allocation, although it does not fully explain the observed patterns.
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ARAÚJO, Erbia Bressia Gonçalves. "Produção de porta-enxerto de cajueiro anão precoce com águas salinizadas e doses de matéria orgânica." Universidade Federal de Campina Grande, 2017. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/770.
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Previous issue date: 2017-08-16<br>No Brasil, a maioria dos pomares de cajueiro está localizada no tropico semiárido, onde os recursos hídricos são escassos e apresentam problemas de salinidade. Diante da importância socioeconômica do cajueiro para região nordeste do Brasil bem como das dificuldades relacionadas a escassez hídrica e qualidade de agua para irrigação, objetivou-se com este trabalho avaliar os efeitos da utilização de diferentes doses de matéria orgânica combinadas com águas de distintos níveis salinos na produção de porta-enxerto de cajueiro. O experimento foi desenvolvido em casa de vegetação (ambiente protegido) do Centro de Ciências e Tecnologia Agroalimentar da Universidade Federal de Campina Grande (CCTA/UFCG), localizado no município de Pombal-PB. O delineamento experimental foi em blocos casualizados, num esquema fatorial 5 x 4, com os tratamentos referentes à cinco níveis de condutividade elétrica da água de irrigação CEa de (0,3; 1,0; 1,7; 2,4 e 3,1 dS m-1 ) em interação com quatro doses matéria orgânica MO (2,5; 3,5; 4,5 e 5,5%). Utilizaram-se três repetições, com duas plantas úteis por parcela, onde se avaliou o clone de cajueiro anão precoce CCP 06. Foram avaliadas as variáveis de diâmetro do caule, número de folhas e área foliar aos 20 e 30 dias após a aplicação dos tratamentos (DAT), taxa de crescimento absoluto e relativo da altura de planta e do diâmetro do caule nos períodos de 10 a 30 DAT, fitomassa fresca e seca de caule, folhas e parte aérea, fitomassa seca de raiz, seca total e o índice de qualidade de Dickson aos 30 DAT. As doses crescentes de matéria orgânica não atenuaram o efeito da salinidade da água de irrigação sobre as variáveis estudadas no presente trabalho. A transpiração, condutância estomática e a fotossíntese líquida dos porta-enxerto de cajueiro CCP 06 diminuem com o acréscimo da salinidade do extrato de saturação do solo.Doses crescentes de MO não reduzem o efeito deletério da irrigação com águas salinizadas sobre a fitomassa e a fisiologia de portaenxerto de cajueiro CCP 06. A irrigação de água CEa de até 2,49, 0,90 e 1,01 dS m-1 , na produção de porta-enxerto de cajueiro CCP 06 promove redução aceitável no crescimento (diâmetro, área foliar e TCRap), fisiologia e fitomassa aos 30 DAT de 10% respectivamente. A dose de matéria orgânica de 2,5% apresentou o melhor resultado para as variáveis estudadas.<br>In Brazil, most of the cashew orchards are located in the semi-arid tropics, where water
resources are scarce and present salinity problems. In view of the socioeconomic importance of
cashew trees in the northeastern region of Brazil, as well as the difficulties related to water
scarcity and water quality for irrigation, the objective of this work was to evaluate the effects
of the use of different doses of organic matter combined with waters of different saline levels
In the production of cashew rootstock. The experiment was carried out in a greenhouse
(protected environment) of the Center for Science and Technology Agro-Food of the Federal
University of Campina Grande (CCTA / UFCG), located in the municipality of Pombal-PB.
The experimental design was a randomized complete block design, in a 5 x 4 factorial scheme,
with the treatments referring to five levels of electrical conductivity of ECw irrigation water of
(0.3, 1.0, 1.7, 2.4 and 3, 1 dS m-1
) in interaction with four organic matter doses OM (2.5, 3.5,
4.5 and 5.5%). Three replicates were used, with two useful plants per plot, where the precocious
dwarf cashew clone CCP 06 was evaluated. The variables of stem diameter, number of leaves
and leaf area were evaluated at 20 and 30 days after application of the treatments (DAT),
absolute and relative growth rate of plant height and stem diameter in periods of 10 to 30 DAT,
fresh and dry stem, leaf and shoot biomass, dry root phytomass, total dry matter and Quality of
Dickson at 30 DAT. Increasing doses of organic matter did not attenuate the effect of irrigation
water salinity on the variables studied in the present study. The transpiration, stomatal
conductance and the net photosynthesis of the CCP 06 cashew rootstocks decrease with the
increase of the salinity of the soil saturation extract. Increasing OM masses do not reduce the
deleterious effect of irrigation with salinized waters on phytomass and physiology Of CCP 06
cashew tree rootstock. ECw water irrigation of up to 2.49, 0.90 and 1.01 dS m-1
in the
production of CCP 06 cashew rootstock promotes acceptable growth reduction (diameter, Leaf
area and TCRap), physiology and phytomass at 30 DAT of 10%, respectively. The organic
matter dose of 2.5% presented the best results for the studied variables.
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Prado, Analissa Pase do. "ASPECTOS AUTOECOLÓGICOS E SILVICULTURAIS DE Eugenia involucrata DC." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/8670.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>This study aimed to obtain scientific information about the species Eugenia involucrata DC
(wild cherry), through analysis of ecological and silvicultural parameters. Initially, in a
remnant of Decidual Seasonal Forest, at the Army Instruction Center of Santa Maria (53 °
52'O and 29 ° 46'S), the trees with ≥ 30 cm were measured in 14 plots of 20 x 100 m, in four
parallel tracks. These plots were subdivided to observe too the population with <30 cm and
seed rain. In the strips with 20 m wide and varied length (total of 8.8 ha), 23 matrix trees ≥ 30
cm were selected in which the reproductive phenology was monitored between August and
December 2007. In November, the seeds were collected and beneficiated, and one sample was
used in seed analysis, for germination test in substrates (paper roll and vermiculite), moisture
content, thousand kernel weight, tetrazolium test and electric conductivity. The other sample
of the seeds was used to assess the development of the seedlings which were produced in
containers of four sizes (tubes 53, 115, 180 and 280 cm3), in the nursery and field. In the
remnant, the species was presented with a stable population, with entrance fee and no
mortality was found, despite the reproductive season. In the population ≥ 30 cm, it was
observed an average increase of 0.5 cm yr-1 and cluster distribution. In this class, the species
showed six individuals per hectare, with 53 individuals with potential for selection in 8.8 ha.
The flowering stage was in the months of September to October, and the fruiting process from
October to November. According to the effective number (Ne), in order to represent the
population, at least 60 fruits from the 23 trees should participate in the collection; however,
only ten individuals produced fruit with varied intensity, forming the plot used in the study. In
the laboratory, no significant difference between substrates (41.9% of germination) was
found, in the tetrazolium test, in the 24 hours of preparation, cross-sectional and 3 hours in a
solution 0.05%, the tissues were visible; the electric conductivity found was 3.54 for 25 mL,
1.93 for 50 mL and 1.48 for 75 mL. There were no significant differences in the emergence
and seedling size for the containers of different sizes, reaching average height (h), stem
diameter (dc) and ratio of height to diameter ratio (h/d): 6.91 cm, 2.27 mm and 3.06,
respectively, after 330 days in the nursery. In the field, the indifference in size remained,
resulting after 330 days, h, dc and h/d, equal to 23.86 cm, 4.26 mm and 5.68, respectively.
The remnant has the potential for collection, however, it will depend on the selection of a
large number of trees (considering the individual s variability production); in the germination
tests, the paper roll allows a greater precision in the analysis, with the first count at 25 days;
for the production of seedlings, the 53 cm³ container can be used.<br>O objetivo deste trabalho foi obter informações científicas sobre a espécie Eugenia involucrata DC. (cerejeira-do-mato), por meio de análise dos parâmetros ecológicos e
silviculturais. Inicialmente, em remanescente de Floresta Estacional Decidual, no Centro de Instruções de Santa Maria (53°52 O e 29°46 S), os indivíduos com CAP ≥ 30 cm foram
quantificados em 14 parcelas de 20 x 100 m, dentro de quatro faixas paralelas. Essas parcelas foram subdivididas, para observar a também a população com CAP < 30 cm e chuva de
sementes. Nas faixas com 20 m de largura e comprimento variado (total de 8,8 ha) foram selecionadas 23 árvores matrizes (CAP ≥ 30 cm), onde a fenologia reprodutiva foi monitorada de agosto a dezembro de 2007. Em novembro do mesmo ano, as sementes foram coletadas e beneficiadas, sendo que, parte foi utilizada na análise de sementes, testando a germinação em (41,9% de germinação); no teste de tetrazólio em 24 horas de pré-condicionamento, corte
transversal e 3 horas em solução 0,05% os tecidos foram visíveis; a condutividade elétrica encontrada foi de 3,54 para 25 mL, 1,93 para 50 mL e 1,48 para 75 mL. Não houve diferenças significativas na emergência e do tamanho das mudas para os diferentes tamanhos de recipiente, atingindo médias de altura (h), diâmetro do colo (dc) e relação altura/ diâmetro do colo (h/d): 6,91 cm, 2,27 mm e 3,06, respectivamente, após 330 dias em viveiro. No campo a
indiferença no tamanho manteve-se, resultando após 330 dias, h, dc e h/d, igual a 23,86 cm, 4,26 mm e 5,68, respectivamente. O remanescente possui potencialidade para coleta, entretanto, dependerá da seleção de maior número de árvores (considerando a produção variável entre indivíduos); nos testes de germinação o rolo de papel permite maior precisão na análise, com primeira contagem aos 25 dias; para a produção de mudas, o recipiente de 53 cm³ pode ser utilizado. substratos (rolo de papel e vermiculita), grau de umidade, peso de mil sementes, teste de tetrazólio e condutividade elétrica. A outra parte das sementes foi utilizada para a avaliação do desenvolvimento das mudas, produzidas em quatro tamanhos de recipientes (tubetes 53,
115, 180 e 280 cm3), no viveiro e campo. No remanescente, a espécie apresentou estabilidade da população, com taxa de ingresso e mortalidade nula, apesar da sazonalidade reprodutiva. Na população com CAP ≥ 30 cm observou-se incremento médio de 0,5 cm ano-1 e distribuição agrupada. Nessa classe, a espécie apresentou seis indivíduos por hectare, com 53 indivíduos potenciais para seleção nos 8,8 ha. A fase de floração foi no período de setembro a
outubro e a frutificação de outubro a novembro. De acordo com o número efetivo (Ne), para representar a população, no mínimo 60 frutos das 23 árvores deveriam participar da coleta,
entretanto somente dez indivíduos produziram frutos com intensidade variada, formando o lote utilizado no estudo. No laboratório, não houve diferença significativa entre substratos
(41,9% de germinação); no teste de tetrazólio em 24 horas de pré-condicionamento, corte transversal e 3 horas em solução 0,05% os tecidos foram visíveis; a condutividade elétrica encontrada foi de 3,54 para 25 mL, 1,93 para 50 mL e 1,48 para 75 mL. Não houve diferenças significativas na emergência e do tamanho das mudas para os diferentes tamanhos de recipiente, atingindo médias de altura (h), diâmetro do colo (dc) e relação altura/ diâmetro do
colo (h/d): 6,91 cm, 2,27 mm e 3,06, respectivamente, após 330 dias em viveiro. No campo a indiferença no tamanho manteve-se, resultando após 330 dias, h, dc e h/d, igual a 23,86 cm, 4,26 mm e 5,68, respectivamente. O remanescente possui potencialidade para coleta, entretanto, dependerá da seleção de maior número de árvores (considerando a produção
variável entre indivíduos); nos testes de germinação o rolo de papel permite maior precisão na análise, com primeira contagem aos 25 dias; para a produção de mudas, o recipiente de 53 cm³ pode ser utilizado.
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Wong, Wai-ting. "Propagating native tree seedlings for forest rehabilitation in Hong Kong, China." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37670578.
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Baumer, Marilyn Cabrini. "Tree Seedling Establishment Under the Native Shrub, Asimina Triloba." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183587955.
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Cline, Erica Theon. "Mycorrhizal fungus communities of Douglas-fir (Pseudotsuga menziesii) seedlings and trees : effects of proximity to residual trees /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/5557.
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Botha, Susan. "The influence of rainfall variability on savanna tree seedling establishment." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/6238.
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Includes bibliographical references (leaves 111-114).<br>My thesis investigates the rainfall requirements necessary for tree seedling survival of different savanna species in the first year of growth. Results from a field drought experiment showed that dry season survival for seedlings of Acacia nigrescens and Philenaptera vialacea was not related to wet season length. Instead mortality was highest immediately after germination despite irrigation to minimize dry spells. Furthermore there was no relationship between seedling size and the length of the dry spell seedlings of Acacia nigrescens and Philenaptera vialacea grown in basalt clay in the greenhouse, could survive. This was in contrast to seedlings of Scleracarya birrea and Terminalia sericea grown in granite sand, where number of dry days survived increased with number of growth days received. There was no significant differences in rainfall variability (t-test: tL III = 1.56, P = 0.121, F-ratio = 1.13) between a semi-arid (Satara) and semi-mesic (Pretoriuskop) site within the Kruger National Park despite significant differences in rainfall totals (t-test: tl, III = 4.40, P < 0.000, F-ratio 3.41). Results from a soil-water model show that seedling recruitment can occur at least twice a decade in the Satara area, which should be frequent enough to allow a transition to a woodland state over time. These results suggest that a mechanism other than the effect of rainfall variability on seedling establishment is required to explain the co-existence of trees and grasses at Satara. The lack of field germination, the absence of a seed bank and the germination of added seed at the field experiment site after rainfall emphasizes seed limitation as an important bottleneck at Satara. Higher herbivore biomass at Satara compared to Pretoriuskop may limit seedling establishment opportunities by destroying seed and seedlings of tree species.
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Bebber, Daniel Patrick. "Dipterocarp seedling growth and mortality in the understorey : roles of herbivory and drought." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289347.
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Ogilvy, Tanya. "Regeneration ecology of broadleaved trees in Caledonian Forest." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/831.
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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.
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Self, Guy K. "Studies of xylopodium formation and early seedling growth in Kielmeyera coriacea Mart." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/14374.
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Padovani, Vera Cristina Ramalho 1965. "Composto de lodo de esgoto como substrato para produção de mudas de arvores nativas e exoticas." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257073.
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Previous issue date: 2006<br>Resumo: Este trabalho tem como objetivo estudar as características físicas e químicas de misturas de diferentes proporções de composto orgânico de lodo de esgoto com casca de arroz carbonizada e avaliar a viabilidade da utilização desses materiais como meio de crescimento para produção de mudas de essências nativas e exóticas. O experimento foi dividido em três fases nas quais foram realizados diversos ensaios. A primeira fase abrangeu a caracterização do lodo de esgoto, do material estruturante e do substrato comercial utilizado no viveiro através de análises químicas. A segunda fase envolveu a realização do processo de compostagem do lodo de esgoto utilizando-se restos de capim e grama cortados, como agente estruturante . Após a compostagem, o lodo de esgoto passou a receber a denominação de COLE ( composto orgânico de lodo de esgoto ) e foi submetido a nova análise química , microbiológica, parasitológica , além da condutividade elétrica. Posteriormente foi misturado com a casca de arroz carbonizada (CAC) nas proporções de 100/00 a 00/100 de COLE/CAC estabelecendo as misturas ou tratamentos que foram submetidos a análises para determinação das propriedades físicas, como macroporosidade, microporosidade, porosidade total , capacidade de retenção de água, densidade aparente . A terceira fase foi dividida em dois ensaios, sendo o primeiro um teste preliminar que utilizou o composto orgânico de lodo de esgoto para a semeadura e cultivo de uma planta indicadora , o tomate, que forneceu resultados que determinaram os tratamentos (substratos) para a instalação do ensaio final , que teve como objetivo o estudo do efeito do substrato na produção de mudas. O segundo ensaio compreendeu a avaliação da produção de essências nativas e exóticas e foi desenvolvido no viveiro municipal da Faculdade Municipal Professor Franco Montoro/Moji Guaçu, onde foram testadas como substrato as proporções 100/00, 90/10,80/20, 70/30, 60/40 (composto orgânico de lodo de esgoto /casca de arroz carbonizada ) utilizando-se tubetes , os quais foram comparados aos substratos testemunhas Plantmax da Eucatex e esterco de curral curtido utilizado pelo viveiro. Foram avaliados parâmetros relativos ao crescimento das mudas: altura de planta (H); diâmetro de colo (D); relação H/D; produção de matéria seca de parte aérea e raiz; relação matéria seca de raiz/matéria seca de parte aérea , área foliar e qualidade de torrão. Os resultados obtidos quanto à caracterização física, microbiológica e química do composto orgânico de lodo de esgoto ( COLE) , indicam que o material está adequado para ser utilizado como meio de propagação de espécies florestais. As mudas de árvores nativas Ingá, Mirindiba rosa e Coração de negro desenvolvidas em substratos contendo composto orgânico de lodo de esgoto ( COLE) / casca de arroz carbonizada (CAC) nas proporções 90/10 e 80/20, apresentaram resultados satisfatórios quando comparados às testemunhas. A espécie exótica Ipê de jardim apresentou bons resultados de crescimento e desenvolvimento das mudas na proporção 90%COLE /10%CAC . Com relação a caracterização nutricional das mudas de Ingá, observou-se que os tratamentos contendo doses de COLE de 70 a 100% apresentaram maior acúmulo de nutrientes nas folhas. A dose de 100% de COLE apresentou resultados superiores em crescimento da parte aérea das mudas, mas insatisfatórios no desenvolvimento das raízes, dificultando a retirada da muda do tubete e interferindo na qualidade final da muda. Com base nos resultados obtidos, conclui-se que o uso do composto orgânico de lodo de esgoto para produção de mudas em tubetes é bastante promissor desde que ele seja utilizado em composição com outro material estruturante , como por exemplo a casca de arroz carbonizada, a fim de se obterem mudas com melhores qualidades fisiológicas e morfológicas<br>Abstract: This work has as objective to study the physical and chemical characteristics of mixtures of different ratios of organic mixture of sewage with carbonized rice straw and to evaluate the viability of the use of these materials as medium of growth for production of seedlings of native and exotic essences. The experiment was divided in three phases where diverse assays had been carried through. The first phase enclosed the characterization of the sewage sludge, the structural material, and the used commercial substratum in the fishery, through chemical analyses. The second phase involved the accomplishment of the process of composting of the sewage sludge using itself cut remaining portions of grass and gram, as structural agent. After the composting of the sewage sludge to be called COLE ( organic mixture of sewage sludge) and was subdue the new chemical analyses , chemical of microorganism and electric conductivity. Subsequently the sewage sludge and mixes the carbonized rice straw, had been carried through analyses for determination of the physical properties, as macroporosity, microporosity, total porosity, water retention capacity , apparent density and electric conductivity. The third phase was divided in two assays, having been first a preliminary test that used the organic mixture of sewage sludge for the sowing and culture of an indicating plant, the tomato, that it supplied resulted that they had determined the treatments (substratum) for the installation of the final assay, that had as objective the study of the effect of the substratum in the production of seedlings. As the second assay understood the evaluation of the production of native and exotic essences and was developed in the municipal fishery of the Municipal College Professor Franco Montoro /Mogi Guaçu, where ratios had been tested as substratum, 100/00 90/10,80/20, 70/30, 60/40 (organic mixture of sewage sludge/ carbonized rice straw) using tubetes, which had been compared with substrate witnesses Plantmax of the Eucatex and dung of tanned corral used for the fishery. Relative parameters to the growth of the changes had been evaluated: height of plant (h); collar diameter (d); relation H/D; dry matter production of aerial part and root; ratio between dry matter of root and aerial part; leaf area and quality of aggregation of the substratum. The gotten results how much the physical, microbiological and chemical characterization, of the organic mixture of sewage sludge (COLE), indicates that the material is adjusted to be used as half of propagation of forest species. The changes of native trees Ingá, Mirindiba rosa and Coração de negro in substrata I contend organic mixture of sewage sludge (COLE)/ carbonized rice straw (CAC) in ratios 90/10 and 80/20, had presented resulted satisfactory when comparative the witnesses. The exotic species Ipê de jardim presented good results of growth and development of the seedlings in the ratio 90%COLE /10 %CAC. With regard to nutrition characterization of the seedlings of Ingá, it was observed that the treatments I contend doses of organic mixture of sewage sludge (COLE) of 70 the 100%, had presented greater accumulation of nutrients in leaf. The dose of 100% of organic mixture of sewage sludge (COLE) presented resulted superior in growth of the aerial part of the seedlings, but unsatisfactory in the development of the roots, making it difficult the withdrawal of the dumb one of container and intervening with the final quality of the seedling . On the basis of the gotten results, the use of the organic mixture of sewage sludge for production of seedlings in containers is concluded that, is sufficiently promising since that, the same either used in composition with another structural agent , as for example the carbonized rind of rice, in order to get seedlings with better physiological and morphologic qualities<br>Mestrado<br>Agua e Solo<br>Mestre em Engenharia Agrícola
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Pei, Ming Hao. "Peridermium pini (Pers.) Lév.-Axenic culture and infection of pine callus tissue cultures and young seedlings." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU553195.
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Axenic cultures of Peridermium pini have been established on modified Shenk &'38 Hilderbrandt's and Harvey &'38 Grasham's media from naturally infected cortex tissues and aeciospore-infected calluses of P. sylvestris and from aeciospores collected from NE Scotland and East Anglia. The cultures occasionally produced immature smooth-surfaced, binucleate spores. Actively growing cultures infected P. sylvestris calluses but not seedlings or trees. In the experiment of fungal nutrition, (NH4)2SO4 appeared essential, sucrose, D-glucose, raffinose and D-sorbitol supported good growth while D-xylose, cellobinose and L-arabinose did not. Opt. medium pH proved to be 5.0-6.0. Axenic cultures were also obtained from 30-40&'37 of single sporelings of some East Anglia spore sources but not from NE Scotland sporelings. When inoculated at a high density, however, all spore sources from both East Anglia and NE Scotland readily formed colonies. Colonies from East Anglia spores mostly appeared smooth at the surface and distinct around margin while those from NE Scotland sources had fluffy surface and irregularly extended periphery. Rapidly expanding hyphal layers developed from both of the colony forms 3 months after inoculation. Callus tissue cultures of P. sylvestris, P. nigra var. maritima and P. mugo vars mughus, rostrata and pumilio were infected by inoculation with aeciospores from NE Scotland. Infections were characterized by formation of aerial hyphae on the callus surface and intercellular hyphae and typical haustoria in the callus tissue. Hyphae from some of the infected calluses penetrated the medium. Seedlings of the pines as above were infected at their cotyledon stage by inoculation with NE Scotland spores. Infections resulted in swelling, death of the seedlings and formation of spermogonia after a year and aecia after two years. Infections of young seedlings of 7 seed sources of P. sylvestris and the UK were examined 6 weeks after inoculation. Discolouration and necrosis of cotyledons were not always related to stem infection.
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Danzer, Shelley R., Steven W. Leavitt, Irina P. Panyushkina, Andreas Mergner, Evelyn Garcia, and Valeria Best-Svob. "Xylem Tracheid Development in Pinus Resinosa Seedlings in Controlled Environments." Tree-Ring Society, 2001. http://hdl.handle.net/10150/262534.
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Progressive tree-ring xylem cell size changes may reveal the influence of changing environment during the growing season. This study examines xylem tracheid cell growth in red pine (Pious resinosa Ait.) seedlings grown in cabinets under controlled environment, where single parameters (temperature, light, soil moisture and CO2) were varied step-wise in each chamber at ca. 30-day increments for ca. 6 months. Control and temperature treatments were replicated. Cross-sections (20 μm thick) sliced with a sliding microtome from each of four seedling stems from each cabinet were mounted on glass slides. Lumen diameters and cell-wall thickness were measured on 4 orthogonal tracheid radial files on 4 radii of each stem. Mean cell sizes were 11-17 μm among treatments and growth periods, whereas numbers of cells formed averaged 0.2-1.3 cells per day. Cell size increased throughout the experiment in most of the treatments, including one of the control treatments and those with the greatest potential to limit growth (decreasing temperature, light and soil moisture). Soil moisture was the only environmental parameter that tended to cause late declining growth, and CO, up to 500 (μmol mol⁻¹ did not appear to influence cell development. Despite a substantial range of environmental shifts in the chambers (100 μmol mol⁻¹ CO₂; 125 μEinsteins m⁻² s⁻¹ light; 8 °C temperature; 35% relative humidity; watering every day to every 5th day), the continued stem elongation and cell-size increases indicate that conditions never became significantly limiting to growth in most treatments. Although the range of environmental variability is undoubtedly much greater in most natural red pine systems, these results indicate that fairly large variations in environment during development of juvenile wood in seedlings may not leave an imprint retrievable from cell-size measurements made on the earliest rings of mature trees.
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Olave, Rodrigo Javier. "Tree seedling production for multifunctional land use systems in cool temperate climates." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426722.
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Konuche, P. K. A. "Influence of light environment on indigenous tree seedlings in Kenya." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/11008.
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Attempts to restock large areas of exploited forests in Kenya have been hampered by inadequate understanding of the ecological requirements of indigenous tree species. In particular, very little is known about the responses of these species to different levels of light. This study, therefore, examined the significance of shade and light in regeneration of some important tree species. The species studied were <I>Cordia africana</I> Lam., <I>Vitex keniensis</I> Turill, <I>Markhamia lutea</I> (Benth.) K. Schum. and <I>Olea capensis</I> L. Artificial shading experiments were carried out in the nursery using seedlings of <I>C.africana</I> and <I>V.keniensis</I>. The effects of different shade levels were compared to full sunlight under low and high nutrient regimes. The response of seedlings transferred among different light environments was also examined. The effects of different levels of light quality (R:FR ratios) were tested. In a forest clearing, seedlings of the four species were grown under artificial shading and their responses were compared to those grown under full sunlight. The influence of deep canopy shade on survival and growth in seedlings of the four species was also determined. In the nursery, seedlings of <I>C.africana</I> and <I>V.keniensis</I> maintained positive relative growth rates at irradiance level of 19% of full sun and their growth was enhanced by increasing irradiance. The supply of nutrients at high level also enhanced the growth. Seedlings transferred between light environments acclimated within a month. Acclimation to increase in light availability was faster than acclimation to decrease. Although acclimation was mainly physiological, biomass was allocated in favour of shoots and roots when seedlings were shaded and exposed respectively. The supply of nutrients at higher level had no effects on the acclimation process.
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Wong, Wai-ting, and 黃煒婷. "Propagating native tree seedlings for forest rehabilitation in Hong Kong, China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37670578.
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Norberg, Gisela. "Steam treatment of forest ground vegetation to improve tree seedling establishment and growth /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-6054-9.pdf.
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Ball, T. "Effect of canopy gaps on tree seedling ecophysiology in a Jamaican montane rainforest." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596313.
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A controlled experiment was established in primary upper montane rain forest (UMRF) in the Blue Mountains of Jamaica to investigate the ecophysiological response of seedlings of seven tree species to canopy gap formation. The group included one invasive species, the Australian tree <I>Pittosporum undulatum,</I> with a mixture of native and endemic shade tolerant and intolerant species. The main aim was to assess whether the known approximate light demand of seedlings of the species for regeneration correlated to the relative ecophysiological performance of the seedlings across a light gradient. Gaps were created artificially by de-branching of canopy trees, ensuring minimal possible damage to the seedling bank. Resulting light levels were equivalent to those associated with damage from a major hurricane. The photosynthetic characteristics, morphology and longevity of shade leaves and seedlings were investigated in naturally growing seedlings on four gap and four understorey control plots. Above- and below-ground competition and the effect of leaf masking and removal were investigated in separate sub-experiments using potted seedlings. In the understorey, mean levels of total diurnal photosynthetic photon flux density (PPFD) on the uppermost leaf were 2.14% of diurnal integrated above canopy levels. No significant variation occurred among the sevens species, whether defined by instantaneous diffuse light (under cloud), or the proportion of cloud-free time for which sunflecks were experienced. The three indices of light level showed strong, though not always 1:1, interrelationships. The findings give strong ecophysiological backing to existing knowledge of the species' regenerational ecology across a range of disturbed and steady state environments in UMRF. They also give information as to relative physiological performance of native species and the problematic invasive tree <I>Pittosporum undulatum. </I>
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Lehto, Tarja Helena. "Role of mycorrhizas in drought resistance of Sitka spruce seedlings." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11045.
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Ashkenazi, Rafael 1958. "Influence of herbicides on establishment of tree seedlings in northern Israel." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277933.
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The influence of the herbicides sulfometuron and simazine on the establishment of 8 species of tree seedlings was studied in northern Israel. The experiment included three treatments and a control. The first treatment applied simazine at a rate of 5 kg/ha, and second treatment applied simazine at a rate of 5 kg/ha and sulfometuron at a rate of 0.03 kg/ha. Sulfometuron was applied alone at a rate of 0.03 kg/ha in the third treatment. Statistical analyses showed significant effects on the survival of some species treated with sulfometuron. To ensure earlier season survival, the rate of sulfometuron applied should be kept at a minimum level to allow both weed control and adequate establishment of seedling. Low-rate applications are particularly important in arid and semi-arid areas.
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Falls, Robert William. "Cambial and photosynthetic activity relations in untreated, wounded, and geotropically stressed white spruce (Picea glauca (Moench.) Voss) seedlings." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30580.
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This thesis reports results of a study of relationships between photosynthetic activity and developmental parameters, and cambial activity (wood formation rate), during and following the period of active wood formation in untreated white spruce seedlings, and in seedlings stressed either by extensive stem incisions, or by tilting.
The approach involved the use of two non-destructive methods for measuring photosynthetic activity: chlorophyll a fluorescence using optical instrumentation, and CO₂ uptake using infrared gas exchange techniques. Photosynthetic development was examined by estimating chlorophyll a content from a specific fluorescence parameter (O-level), and by the relative occurence of specific chloroplast stroma and membrane (thylakoid) proteins using electrophoretic and immunoblotting techniques. Cambial activity was determined using digitized image analysis of prepared cross-sections of seedling stems.
Several fluorescence parameters were strongly correlated to cambial activity in untreated seedlings during the period of active wood formation (in mid-summer). However, the correlations were severely diminished or non-existent when cambial activity was arrested (in late-summer and autumn). Correlations between fluorescence and cambial activity in stressed seedlings were not discernible at any time, suggesting that the induced stresses resulted in a substantial alteration in normal source:sink relationships. Carbon dioxide uptake measures, either uncorrected or corrected to estimated chlorophyll α content, were not measurably correlated to cambial activity in untreated or stressed seedlings at any time in this system.
Chlorophyll α content estimated from O-level fluoresecence, was not related to cambial activity in untreated or stressed seedlings. The relative occurences of two enzymes and proteins associated with photosynthetic carbon fixation, i.e. ribulose 1,5-bisphosphate carboxylase (Rubisco) and Coupling Factor, did not appear to be influenced by applied wounding and geotropic stresses.
In contrast to the strong correlations found between fluorescence parameters and current season stem vigour, pre-season seedling height and cross-sectional stem areas were not related to stem vigour. These results suggest that in unstressed white spruce seedlings, the measure of specific chlorophyll α fluorescence parameters, using the methods
delineated in this study, offers an alternative and more strongly predictive means of assessing current stem vigour, than measures of seedling dimensions.
The results of this study provide strong evidence for, and a degree of elucidation on, the anticipated but previously unestablished existence of a source:sink relationship between leaves and vascular cambium in conifer seedlings. This information should provide an initial foundation for the elucidation of non-invasive methodologies by which to assess stem vigour of white spruce seedlings, and to probe source:sink relationships in other conifer species.<br>Science, Faculty of<br>Botany, Department of<br>Graduate
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West, Lee. "Effects of Soil Fungi on Tree Seedling Establishment in a Southeastern Coastal Plain Forest." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/46180.
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Effects of fungi and overstory composition on tree seedling survival and growth were investigated in closed canopy upland forests in the coastal plain of South Carolina. Seedlings of Quercus alba, Cornus florida and Pinus taeda were planted in the understory of two forest types -naturally regenerated hardwood and planted pine. Fungal species composition and biomass were experimentally manipulated with a treatment of the fungicide captan.
In contrast with other studies conducted in different systems (sand dune, grassland, and old field), the effects of soil fungi were minor in a closed canopy forest. Only Q. alba showed a significant response to the fungicide (p < 0.05) treatment with increased growth.
Overstory composition had no significant effect on growth or survival for any of the species. Both of the commercially desirable species (Q. alba and P. taeda) had reasonable survival ( @ 60%). Both also maintained positive, though modest, growth. This suggests that an advance regeneration pool could be established successfully by artificial regeneration.<br>Master of Science
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Lett, Signe. "Mosses as mediators of climate change : implications for tree seedling establishment in the tundra." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-130942.
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Alpine and arctic tree line expansion depends on the establishment of tree seedlings above the current tree line, which is expected to occur with climate warming. However, tree lines often fail to respond to higher temperatures. Other environmental factors are therefore likely important for tree seedling establishment. Above the tree line, establishing seedlings encounter existing vegetation such as bryophytes, which often dominate in arctic and alpine tundra. Bryophytes modify their environment in various ways and may mediate climate change effects on establishing tree seedlings, and with that tree line expansion. The aim of this thesis was to understand if and how the environment, in particular bryophytes, mediates the impact of climate change on tree seedling establishment at the alpine and arctic tree line. This was explored by reviewing literature on tree seedling establishment at alpine and arctic tree lines globally. In addition, tree seedling survival and growth of Betula pubescens and Pinus sylvestris were assessed experimentally. Here, individuals were planted into mono-specific mats of different bryophytes species and exposed to warming and different precipitation regimes. The literature review revealed that besides from temperature, tree seedling establishment is affected by a wide range of abiotic and biotic factors including water, snow, nutrients, light, disturbance and surrounding vegetation. Furthermore the review revealed that for example vegetation can change tree seedling responses to climate change. The experiments showed that especially tree seedling survival was adversely affected by the presence of bryophytes and that the impacts of bryophytes were larger than those of the climate treatments. Seedling growth, on the other hand, was not hampered by the presence of bryophytes, which is in line with earlier findings that seedling survival, growth and seed germination do not respond similarly to changes in environmental conditions. Moreover, we found several indications that vegetation above the tree line, including bryophytes, mediated tree seedling responses to warming and precipitation or snow cover. This thesis shows that temperature alone should not be used to predict future tree seedling establishment above the alpine and arctic tree line and that extrapolations from climate envelope models could strongly over or under estimate tree line responses to warming. This underlines the value of multi-factorial studies for understanding the interplay between warming and other environmental factors and their effects on tree seedling establishment across current tree lines.
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Walker, John F. "The Inhibitory Effect of Rhododendron maximum L. (Ericaceae) Thickets on Mycorrhizal Colonization of Canopy Tree Seedlings." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/46489.
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Thickets of Rhododendron maximum (Rm) in the southern Appalachians impose severe limitations on the regeneration of hardwood and coniferous seedlings. Interactions between Rm thickets and ectomycorrhizal colonization were examined to explain seedling inhibition. Experimental blocks were established in and out of Rm thickets in a mature, mixed hardwood/conifer forest in Macon County, North Carolina. Planted seedlings of red oak (Quercus rubra) and hemlock (Tsuga canadensis) were harvested at the end of the first and second growing seasons. Litter manipulation had no effect on total mycorrhizal colonization. Mycorrhizal colonization and ramification index (# mycorrhizae cm-1) were depressed and colonization by Cenococcum geophilum increased in blocks with versus without Rm. After the first year, percent colonization of T. canadensis not in Rm thickets (62 %) was three times higher than in Rm thickets (19%), and the ramification index was increased by more than a factor of four (2.83 versus 0.61). Mycorrhizal colonization levels were correlated with root weight and shoot weight in both hemlock and oak seedlings, but did not explain most of the variation observed. Sporocarps of 69 putatively ectomycorrhizal species were collected on the blocks. Species diversity and overall community structure was similar in and out of Rm thickets. Individual species, i.e. Lactarius speciosus and Russula krombholzii, were significant indicators of forest without Rm thickets. Rhododendron maximum thickets probably affect the process of mycorrhization. The reduced level of mycorrhizal capacity under Rm thickets could be a factor in the increased seedling failure in Rm thickets.<br>Master of Science
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Warrillow, Michael P. "Ecological Impact of Glaze Storm Damage in an Appalachian Oak Forest." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31507.
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Glaze damage to canopy trees, gap size and seedling regeneration was surveyed relating to site topographic features after a major glaze storm at Fishburn Forest in the central Appalachian mountain region. The survey sites were stratified according to aspect and landform, and sample plots were randomly assigned to each topographic category. The canopy trees in the plots were tallied and their damage was visually classified.
The results demonstrated that different species had different susceptibilities to glaze damage and susceptibility of species varied as topography changed. Virginia pine was the most susceptible species. In general, trees had the greatest damage on steep slopes and eastern aspects, and least damage on toe-slopes. Some species varied greatly in their susceptibility to glaze damage across the topographic categories, such as red maple, while some species varied little, like blackgum. Basal area was reduced 6% and varied due to species and topography.
Where glaze damage was severe, gaps in the forest canopy were created. Gap sizes and the effects of gap size and topography on seedling regeneration within gaps caused by glaze damage were assessed. Seedlings were tallied by species and height in microplots within each sample plot and in the nearest gap, where gap size was measured. Gap size varied from 14,000 m2 to less than 20 m2. Average gap size was 255 m2. Canopy tree damage, forest type and topography were the most important factors affecting gap size. Gaps tended to be larger on steep backslopes. Common seedling species in both gaps and understory were sassafras, serviceberry and red maple. Disturbance affected both seedling height and density, as did topography. However gap size had effect only on seedling height. The future forest in this area is unlikely to change significantly, as species composition of seedlings was largely unaffected by the glaze storm damage.<br>Master of Science
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See, Lee Su. "Some aspects of the biology of mycorrhizas of the Dipterocarpaceae." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334651.
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Little is known of the biology and importance of the ectomycorrhizal symbiosis in the Dipterocarpaceae. This project was undertaken: 1) to follow dynamics of mycorrhizal infection of dipterocarp seedlings at different sites in the forest, to characterise the major fungal associations involved; 2) to follow mycorrhizal infection of dipterocarp seedlings under laboratory conditions with different inoculum sources; 3) to determine whether dipterocarp ectomycorrhizas function in a manner similar to temperature ectomycorrhizas in the uptake of specific nutrients. Twenty-four different ectomycorrhizal types were described from roots of newly germinated seedlings, two to seven month-old seedlings and wildings of <i>Shorea leprosula</i> (Miq.), and approximately 20 year-old <i>S. acuminata</i> Dyer, <i>S. dasyphylla</i> Foxw., <i>S. leprosula</i> and <i>S. parvifolia</i> Dyer trees. Seventeen types were tentatively identified to family level. Vesicular-arbuscular mycorrhizas were not found. In the forest, some 14 day-old <i>S. leprosula</i> seedlings were already ectomycorrhizal but infection could be absent up to seven months after germination. The results implied that hyphal connections were important in early infection of seedlings in the vicinity of parent trees. Mycorrhizal infection of sequentially sampled two to seven month-old seedlings declined over the sampling period at two sites in Gombak, Selangor and one in Ulu Langat, Selangor. Five to six ectomycorrhizal types were dominant on seedlings at each site and a succession of types was observed on seedling roots. At final harvest, increased plant growth was significantly correlated with ectomycorrhizal infection only at one site in Gombak where infection by 'dominant' types exceeded 30%. Non-mycorrhizal seedlings of <i>S. acuminata, S. leprosula, Hopea helferi</i> and <i>H. odorata</i> were able to grow normally in sterile soil under non-competitive situations. Seedlings were able to form ectomycorrhizas even with inoculum present in grassland soils or with inoculum from different host species in the case of <i>H. helferi</i>. Increased phosphorus uptake by ectomycorrhizal seedlings of <i>S. acuminata, S. leprosula</i> and <i>H. odorata</i> was demonstrated.
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Stefanescu, Carla. "Cost-benefit theory of leaf lifespan using seedlings of tropical tree species." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015764.
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Ffolliott, Peter F. "Initial Survival and Growth of Tree Seedlings in a Water Harvesting Agrisystem." Arizona-Nevada Academy of Science, 1988. http://hdl.handle.net/10150/296410.
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From the Proceedings of the 1988 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 16, 1988, University of Arizona, Tucson, Arizona
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Lammerant, Roel. "Impact of experimental soil moisture manipulation on tropical tree seedling demographic fates and functional traits." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-436103.
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In tropical regions, climate change is predicted to lead to increased drought frequency and intensity. The extent to which this will shift the functional diversity of tropical tree communities is unknown due to a limited understanding about the response of seedlings to variable soil moisture. We addressed this issue using an experimental approach in the Luquillo Experimental Forest, Puerto Rico. We exposed seedlings of eight tree species, representing different successional stages, to an experimental soil moisture gradient. We evaluated (1) How species mean trait values relate to species-specific demographic responses to drought, (2) How intraspecific variation in functional traits relates to a soil moisture gradient, (3) The extent to which demographic response to short-term experimental drought mirrored long-term demographic response of seedlings to natural variation in soil moisture. Growth and survival of species with more `conservative` functional strategies tended to be more sensitive to a change in soil moisture and more tolerant to drought compared to species with more `acquisitive` strategies. In addition, traits of individual seedlings within species varied with respect to soil moisture, suggesting a potential role for phenotypic plasticity in response to drought. Specifically, this response was significant for three species (Inga laurina, Guarea guidonia, Schefflera morototoni) and was primarily associated with relative carbon investment in leaves and roots. Species demographic responses to soil moisture in experimental and long-term studies were weakly positively correlated but more variables are at play under natural conditions, which partly decouples these responses. Overall, our results suggest that tree species with `conservative` functional strategies are likely to become more common under increasing drought frequency and intensity in the Luquillo Mountains of Puerto Rico. However, understanding the broader implications of our findings will require considering the effects of other disturbances, including hurricanes, which may have contrasting effects. Furthermore, intraspecific variation in functional traits is likely to influence how the seedlings of tropical tree species cope with drought.
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ATHY, ERIN R. "EFFECTS OF MULCH ON TREE SEEDLING SURVIVAL AND EDAPHIC CONDITIONS ON A CLOSED OHIO LANDFILL." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1070486322.
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Johnsen, Kurt H. "Root growth potential and bud dormancy of three northern pines with emphasis on eastern white pine." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/87644.
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A two year study examined Root Growth Potential (RGP) in a hydroponic system and Dormancy Release Index (DRI) in one-year-old (1-0) and two-year-old (2-0) eastern white pine (Pinus strobus L.), red pine (Pinus resinosa Ait.), and Scotch pine (Pinus sylvestris L.) seedlings with emphasis on eastern white pine. During 1985-86 all three species of 2-0 stock displayed a similar pattern of RGP with high levels of RGP limited to mid-March. Only 2-0 eastern white pine had a statistically significant relationship between RGP and DRI; however, this relationship was not consistent in 1986-87. The RGP/DRI relationship in 2-0 eastern white pine was strong over both years within a DRI range of 0.22 to 1.00. One-year-old and 2-0 eastern white pine stock had very different patterns of RGP over both years with 1-0 stock maintaining much wider "lifting windows" for high RGP. Cold storage (2C) of 2-0 eastern white pine resulted in variable effects on RGP although it typically progressed dormancy release.
There were no strong RGP trends between northern and southern provenances of 1-0 eastern white pine and heritability values indicate that RGP is under minimal genetic control in 1-0 eastern white pine seedlings. Northern and southern provenances did display clear differences in seedling morphology and seasonal patterns of shoot activity.
Results of a field outplanting study show that RGP does show promise as a measure of 2-0 eastern white pine seedling quality. The predictive ability of RGP was increased on non-irrigated versus irrigated seedlings. A comparison of greenhouse versus growthroorn RGP testing demonstrated the validity of using greenhouse RGP testing of 2-0 eastern white pine.<br>M.S.
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Jennings, S. B. "The response of tree seedlings to canopy disturbance in an Amazonian rain forest." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361951.
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Bloor, J. "Effects of light on the performance of shade-tolerant tropical rainforest tree seedlings." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596725.
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This thesis set out to investigate the light responses of shade-tolerant tropical tree species, and to assess whether or not there was a trade-off between shade tolerance and responsiveness to high light. Shadehouse experiments indicated that low-light relative growth rate was positively correlated with that of high light across species, and all seedlings showed typical 'sun' and 'shade' characteristics when grown in high- and low-light survival amongst the species studied. These trends were mirrored in forest-growth plants. Seedling mortality rate in the forest varied across species and was driven by vertebrate herbivory rather than light availability. In the shadehouse studies, seedling light responses did not appear to be confounded by nutrient limitation. Some evidence was found for phylogenetic effects across species, particularly in root morphology. Ontogenetic effects were also found for a number of plant traits, although the significance of these effects was not consistent across species. Species showed changes in growth ranking both across light levels and over time, suggesting a role for shifting competitive hierarchy in promoting species coexistence. The shade-tolerant species studied also varied significantly in the flexibility of their plant traits in response to changes in light conditions. Nonetheless, all species showed significant acclimation to an increase in light in terms of growth, photosynthesis, morphology and architecture. Acclimation to a decrease in light involved a significant decrease in photosynthetic rate and growth across species, but changes in morphology were limited.
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Mangan, Scott A. "Importance of the species composition of arbuscular mycorrhizal fungi to tropical tree seedlings." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3243802.
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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007.<br>Title from PDF t.p. (viewed Nov. 18, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6842. Adviser: James D. Bever.
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Alvarez-Clare, Silvia. "Biomechanical properties of tropical tree seedlings as a functional correlate of shade tolerance." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009261.
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Higuita, Didier Mauricio Chavarriaga. "Biological control of Fusarium spp. and other soil-borne pathogens on tree seedlings." Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602315.
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Soil borne fungi isolated from forest areas and nurseries in North east of Scotland using baiting techniques, were identified using classical taxonomy and molecular methods (PCR amplification of ITS regions; restriction digestion; sequencing of PCR products) as Fusarium lateritium, F. tricinctum, F. sambucinum, Phytophthora cinnamomi, Pythium ultimum var. ultimum and Rhizoctonia binucleate (Ceratobasidium sp.). Virulence was tested in vitro on young seedlings of Pinus sylvestris and Alnus glutinosa, and Koch's postulates fulfilled through reisolation of the pathogens and confirmation of fungal penetration into host tissues. Root growth was measured using the Winrhizo program, and dry weights recorded. Symptoms on aerial parts were assessed using a categorical scale from 0 (healthy) to 5 (damage > 76%). Fusarium spp. caused significant different (P 0.01) symptom intensity on both host plants. However, no significant difference in root growth was found between treatments and control (P 0.05). The effects of different compost treatments on disease development in seedlings of both hosts inoculated with the same fine root pathogens was tested in the glasshouse confirming the virulence of the fungal pathogens on P. sylvestris and A. glutinosa seedlings. Although mean dry weights of P. sylvestris and A. glutinosa varied between compost treatments, differences were not significantly different. Isolation, characterization and identification of bacterial isolates, Bacillus subtilis B1, fluorescent pseudomonads B4 and B5 with antagonistic action against pathogens were also carried out. These isolates along with the known bacterial antagonists Bacillus subtilis MB600, MB205 and Pseudomonas corrugata R117 were used for biological control in vitro and in planta experiments using Alnus glutinosa or Pinus sylvestris seedlings. All bacterial isolates colonized root systems of both tree species. Higher numbers of bacterial cells were observed on roots of A. glutinosa than on P. sylvestris roots. High bacterial cell numbers were observed in plants of both tree species inoculated with fluorescent pseudomonads B4 or B5. In vitro antagonism on agar plates, indicated by inhibition in fungal colony diameter growth, was recorded for F. tricinctum, F. lateritium and F. sambucinum, Pythium ultimum var. ultimum and Phythophthora cinnamomi with all bacterial isolates tested (P 0.05). Biological control of the fine root pathogens on Pinus sylvestris and Alnus glutinosa seedlings by bacteria semi in vivo in test tubes was carried out with various responses in both tree hosts. All bacterial treatments resulted in a lower sporangium germination rate for P. ultimum var. ultimum than was found in controls (P 0.05). Effect of the bacterial isolates separately on growth and disease development in Pinus sylvestris and Alnus glutinosa seedlings inoculated with the pathogens under glasshouse conditions using autoclaved compost was tested. The bacterial isolates had various effects against the pathogens, although in most cases no significant differences were observed relative to controls. Further soil-based trials were carried out in the glasshouse to achieve control of root disease development on Pinus sylvestris and Alnus glutinosa using a combination of different antagonists, based on a mixture of the bacterial isolates used previously and Trichoderma koningii (TC6-Colombia). None of the antagonistic treatments showed a clear antagonistic effect in Pinus sylvestris against the fungal infections compared to control plants inoculated with the pathogens alone. In contrast, in Alnus glutinosa plants T. koningii co-inoculation improved plant growth in several of the growth parameter measured.