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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A physiological and morphological analysis of the effects of nitrogen supply on the relative growth rates of nine loblolly pine (Pinus taeda L.) clones

Stover, Corey Michael 16 August 2006 (has links)
The influence of nitrogen supply on relationships of relative growth rate (RGR) to leaf physiology, structural and non-structural carbon partitioning, and nitrogen- and water-use efficiencies were examined in loblolly pine (Pinus taeda L.) clonal lines differing in growth potential. Nine 18-month-old loblolly pine clones were grown in a climate-controlled greenhouse for 20 weeks under two contrasting nitrogen (N) regimes (50 and 250 ppm) and a growth analysis was carried out. Higher nitrogen increased plant RGR and largely resulted in proportional shifts in biomass from roots and stems to needles. The RGR of plants receiving higher nitrogen was increased primarily through increased leaf area ratio (LAR), which was increased through higher leaf mass fraction (LMF) and not through changes in needle morphology. Although concentrations of needle glucose in plants receiving 250 ppm N were 22 percent higher than plants receiving lower N, total non-structural carbohydrate concentrations in needles of plants receiving 50 ppm N were nearly double that of clones receiving 250 pm N, primarily due to starch accumulation of the nitrogen-deficient plants. Plants receiving 250 ppm N also had 39 and 18 percent lower starch in the coarse and fine roots, respectively. Plants receiving higher nitrogen were also more water-use efficient, but had lower photosynthetic nitrogen-use efficiency. LAR, net assimilation rate (NAR), specific leaf area (SLA), and LMF were all positively correlated with RGR, but the main influence on RGR differences among clones was LAR. In addition, leaf-level rates of photosynthesis and respiration were positively correlated with RGR; however, faster-growing clones did not exhibit greater carbon economy at the leaf level. Both instantaneous water-use efficiency (A/E) and δ13C were positively correlated with RGR and photosynthetic nitrogen-use efficiency was negatively correlated with RGR. The identification of physiological and morphological traits underpinning differences in RGR among clones and how these traits are affected by nitrogen supply provides new information on trait correlations within species and parallels broader patterns observed among species.
2

A physiological and morphological analysis of the effects of nitrogen supply on the relative growth rates of nine loblolly pine (Pinus taeda L.) clones

Stover, Corey Michael 16 August 2006 (has links)
The influence of nitrogen supply on relationships of relative growth rate (RGR) to leaf physiology, structural and non-structural carbon partitioning, and nitrogen- and water-use efficiencies were examined in loblolly pine (Pinus taeda L.) clonal lines differing in growth potential. Nine 18-month-old loblolly pine clones were grown in a climate-controlled greenhouse for 20 weeks under two contrasting nitrogen (N) regimes (50 and 250 ppm) and a growth analysis was carried out. Higher nitrogen increased plant RGR and largely resulted in proportional shifts in biomass from roots and stems to needles. The RGR of plants receiving higher nitrogen was increased primarily through increased leaf area ratio (LAR), which was increased through higher leaf mass fraction (LMF) and not through changes in needle morphology. Although concentrations of needle glucose in plants receiving 250 ppm N were 22 percent higher than plants receiving lower N, total non-structural carbohydrate concentrations in needles of plants receiving 50 ppm N were nearly double that of clones receiving 250 pm N, primarily due to starch accumulation of the nitrogen-deficient plants. Plants receiving 250 ppm N also had 39 and 18 percent lower starch in the coarse and fine roots, respectively. Plants receiving higher nitrogen were also more water-use efficient, but had lower photosynthetic nitrogen-use efficiency. LAR, net assimilation rate (NAR), specific leaf area (SLA), and LMF were all positively correlated with RGR, but the main influence on RGR differences among clones was LAR. In addition, leaf-level rates of photosynthesis and respiration were positively correlated with RGR; however, faster-growing clones did not exhibit greater carbon economy at the leaf level. Both instantaneous water-use efficiency (A/E) and δ13C were positively correlated with RGR and photosynthetic nitrogen-use efficiency was negatively correlated with RGR. The identification of physiological and morphological traits underpinning differences in RGR among clones and how these traits are affected by nitrogen supply provides new information on trait correlations within species and parallels broader patterns observed among species.
3

Dominance/Suppression Competitive Relationships in Loblolly Pine (Pinus taeda L.) Plantations

Dyer, Michael E. 20 November 1997 (has links)
Data from three long-term field studies with loblolly pine (Pinus taeda L.) plantations were used to examine inequality (Gini coefficient) trends in diameter and the relationship between diameter relative growth rate (r) and initial size. Analysis with two spacing studies shows inequality increases with increasing density. For a given initial density, inequality initially decreases and then begins to increase as trees compete for resources. The slope of the linear relationship between r and relative size also increases with increasing density. The slope is initially negative and switches to positive as competition intensifies. The switch in the slope of the r/size relationship occurs when the crown projection area exceeds 1.05 or when the crown ratio falls below 0.75. These results are consistent with the resource pre-emptive or dominance/suppression theory of intra-specific competition. The r/size trends are not evident when calculations are based on class means as opposed to individual trees. The slope of the r/size relationship is a function of stand height, density, and to a lesser extent, site quality. Density reduction through mid-rotation thinning tends to decrease the slope coefficient. The r/size trends are used to develop a disaggregation model to distribute stand-level basal area growth over an initial tree list. This approach compares well with two other disaggregation models but tends to over predict growth on the largest trees. / Ph. D.
4

Desempenho de três espécies arbóreas nativas de cerrado introduzidas em uma área antropizada no município de Porto Nacional, Tocantins

Cabral, Eiderson Silva 27 March 2017 (has links)
Objetivou-seanalisar o crescimento de Anacardium occidentaleL.(Anacardiaceae), Dipteryx alataVogeleParkia platycephalaBenth (Fabaceae), introduzidas em uma área de Cerrado sentido restritoemPorto Nacional, Tocantins. Foram analisados 30 indivíduos de A. occidentale, 16 de D. alatae 34 de P. platycephala, com análises realizadas nos anos de 2006, 2010 e 2016. Foram avaliadas a altura das plantas e o diâmetro dos caules. Esses dados também foram utilizados para o cálculo das taxas de crescimento relativo em altura e em diâmetro. P. platycephala exibiu os maiores incrementos em altura e diâmetro, como também as maiorestaxas de crescimento relativo, mostrando-se a espécie melhor adaptada às condições ambientais da área. A. occidentale e D. alataapresentaram crescimento em altura e diâmetro bem como taxas de crescimento relativo menores, o que dificultou a adaptação dosindivíduos ao ambiente onde foram introduzidos. / Aimed at analyzing the growth of Anacardium occidentaleL.(Anacardiaceae), Dipteryx alataVogel andParkia platycephala Benth (Fabaceae), introduced in a Cerrado stricto sensu area in Porto Nacional, Tocantins. Thirty individuals of A. occidentale, 16 of D. alataand 34 of P. platycephalawere evaluated according to data collected in 2006, 2010 and 2016. Plant height and stem diameter were assessed. These data were also used to determine the relative growth rates of stem height and diameter. P.platycephalaexhibited the greatest increments in height and stem diameter as well as the largest increases in relative growth rates, turning out to be the species that best adapted to the environmental conditions of the area. A. occidentale and D. alata presented lower increments in terms of height, stem diameter and relative growth rates, which hindered the adaptation of individuals to the environment where they were introduced.
5

Maturidade sexual morfológica do caranguejo violinista uca maracoani (brachyura, ocypodidae) no manguezal do Rio Formoso, Pernambuco, Brasil

COSTA, Cibele Leandro da 29 May 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-29T15:10:20Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Cibele Leandro da Costa.pdf: 1508703 bytes, checksum: 5ef74f8b7dea8d844172b02f0d834576 (MD5) / Made available in DSpace on 2016-04-29T15:10:20Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Cibele Leandro da Costa.pdf: 1508703 bytes, checksum: 5ef74f8b7dea8d844172b02f0d834576 (MD5) Previous issue date: 2015-05-29 / CAPEs / O crescimento relativo do caranguejo violinista Uca maracoani foi analisado em uma população do manguezal do Rio Formoso, no estado de Pernambuco, Nordeste do Brasil. Os caranguejos foram coletados manualmente, por uma pessoa com um esforço de captura de 30 minutos durante a maré baixa durante no período de um ano, de abril de 2009 a março de 2010. Os caranguejos de ambos os sexos foram medidos com um paquímetro nas seguintes dimensões: largura da carapaça (LC), comprimento da carapaça (CC), comprimento própodo do quelípodo (CPQ), maior altura do própodo do quelípodo (AQ) e largura do abdome (LA). Além disso, os machos também foram medidos quanto ao comprimento gonadal (CG). Estas medidas corporais foram submetidas a uma análise K-means. Em seguida, uma análise discriminante bivariada foi realizada, para separar os dados em duas categorias etárias: caranguejos juvenis e adultos. Após a separação, cada categoria foi agrupada em dezesseis classes de LC; a proporção de adultos em cada classe de tamanho foi estimada e ajustada com uma equação logística. Uma interpolação foi realizada para determinar o LC para a qual 50% dos machos e fêmeas foram morfologicamente maduros. As relações CPQ vs. LC e LA vs. LC evidenciaram alometria positiva para juvenis e adultos machos e fêmeas. No entanto, uma alometria negativa foi observada na relação CC vs. LC e CG vs. LC para juvenis e adultos do sexo masculino, LA vs. LC para machos adultos e, AQ vs. LC para fêmeas adultas. O crescimento padrão mostrado no abdome da fêmea está provavelmente relacionado a incubação dos ovos e o crescimento excessivo observado no quelípodo do macho deve estar relacionado a processos reprodutivos, porque este apêndice é usado na corte e nas interações agonísticas intra ou inter específicas com outros machos. As relações morfométricas que melhor evidenciou o início da maturidade sexual morfológica para U. maracoani foram CPQ vs. LC para machos e LA vs. LC para fêmeas. Machos e fêmeas são maduros, respectivamente em 17,9 e 16,0 mm de LC. / The relative growth of the fiddler crab Uca maracoani was analysed in a population from Rio Formoso mangrove, state of Pernambuco, northeast Brazil. The crabs were sampled manually, with a capture effort by one person during 30 minutes of the low tide during a period of year from April 2009 to March 2010. Crabs of both sexes were measured with a calliper at following dimensions: carapace width (CW), carapace length (CL), major cheliped propodus length (CPL), major cheliped propodus height (CPH) and abdomen width (AW). Besides, the males were also measured at the gonopod length (GL). These body measurements were subjected to a K-means clustering analysis. Then, a bivariate discriminant analysis was performed, to separate the data into two age categories: juveniles and adults crabs. After the separation, each category was grouped into sixteen classes of CW; the proportion of adults in each size class was estimated and fitted to a logistic equation. An interpolation was performed to determine the CW at which 50% of the males and females were morphologically mature. The relationships CPL vs. CW and AW vs. CW evidenced positive allometry for juveniles and adults males and females. However, a negative allometry was observed in the relationship CL vs. CW and GL vs. CW for juveniles and adults males, AW vs. CW for adults’ males and, CPH vs. CW for adults’ females. The pattern growth shown at the female abdomen probably is related to egg incubation and the excessive growth observed at the male cheliped must be related to reproductive process, because this appendage is used at the courtship and intra or inter specific agonistic interactions with other males. The morphometric relationships that best evidenced the beginning of the morphological sexual maturity for U. maracoani were CPL vs. CW for males and AW vs. CW for females. Males and females are mature, respectively at 17.9 and 16.0 mm CW.
6

Biologia populacional de Uca victoriana no manguezal de Itacuru??/Coroa Grande, Ba?a de Sepetiba, RJ. / Population biology of Uca victoriana in mangrove of Itacuru??/Coroa Grande, Sepetiba Bay, RJ.

PEREIRA, Dayane Lucia Francisco 28 June 2012 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-20T20:59:12Z No. of bitstreams: 1 2012 - Dayane Lucia Francisco Pereira.pdf: 2956056 bytes, checksum: b41eef6a294a563d5ce755f819d3329d (MD5) / Made available in DSpace on 2017-06-20T20:59:12Z (GMT). No. of bitstreams: 1 2012 - Dayane Lucia Francisco Pereira.pdf: 2956056 bytes, checksum: b41eef6a294a563d5ce755f819d3329d (MD5) Previous issue date: 2012-06-28 / CAPES / Uca victoriana von Hagen, 1987 is a crab belonging to the family Ocypodidae typical from intertidal zones, characterized by a strong sexual dimorphism. This current study was elaborate in order to evaluate the information about biology of the population, more specifically about population structure, spatial distribution, and reproductive aspects of U. victoriana from mangrove of Itacuru?? / Coroa Grande located in Sepetiba Bay, RJ. Three transects were established with three areas on the right bank of the Draga river, and each area containing 10 m long and 2.25 m wide. Crabs were collected monthly during the period of November 2010 to October 2011. The animals were collected using a quadrat of 30 x 30 cm, performing three random replicates in each plot. In laboratory, the animals were separated by sex and it were taken biometric measurements such as carapace width, carapace length, abdomen width, height of the larger chelipod, length of the larger chelipod and length of the gonopod. Sediment samples were collected in three transects to determine the granulometric composition. It was collected a total of 529 individuals in the study period, of which 89 were males, 97 females non-ovigerous, 16 ovigerous females and 327 juveniles. In the population structure the frequency distribution of males and females was unimodal. The average size of the female LC was 5,64 ? 1,73 mm and 4,97 ? 1,53 mm for males. The analysis of size comparison between sexes showed that females are significantly larger (U = 23741.5, p <0.001) than males. The overall sex ratio of population was 1,94:1, predominantly males. In spatial distribution, there was a greater abundance of animals in the area 2, where the predominance of juveniles, ovigerous females and non-ovigerous females was not superior to other transects. The average size of the ovigerous females was 6.67 ? 0.60 mm, ranging from 5.38 to 7.70 mm. Mean fecundity was 424 ? 186 eggs, with a range from 211 to 886 eggs. The average size of the eggs was 0.292 ? 0.011 mm, with a width 0.27 to 0.30 mm. Recruitment occurred in April. The morphological maturity of females was estimated for the size 5.0 mm and 5.9 mm for males. It follows that the U. victoriana population from mangrove studied, showed to be stable, showing juveniles during all of the months. The distribution of U. victoriana was not influenced by temperature or granulometric, suggesting that other factors, for example, the abundance of trees or biologic factors could influence their distribution in the mangrove. The fecundity found in this population correlates with the females size, as occurs in most brachyuran. The reproductive period was seasonal, with higher frequency of ovigerous females in the months of September and October. / A esp?cie Uca victoriana von Hagen, 1987 ? um caranguejo pertencente ? fam?lia Ocypodidae, t?pico de zonas entremar?s, caracterizado por um forte dimorfismo sexual. O presente trabalho teve como objetivo obter informa??es sobre a biologia populacional, mais especificamente em rela??o ? estrutura populacional, distribui??o espacial e aspectos reprodutivos de U. victoriana do manguezal de Itacuru??/Coroa Grande localizado na Ba?a de Sepetiba, RJ. Foi estabelecido um transecto com tr?s ?reas na margem direita do rio da Draga, onde cada ?rea tinha 10 m de comprimento por 2,25 m de largura. Os caranguejos foram coletados mensalmente durante o per?odo de novembro de 2010 a outubro de 2011. Os animais foram coletados utilizando-se um quadrat de 30 x 30 cm, realizando-se tr?s r?plicas aleat?rias em cada parcela. No laborat?rio os animais foram separados por sexo e tomadas as medidas biom?tricas, como a largura da carapa?a, comprimento total, largura do abdome, comprimento do maior quel?podo, altura do maior quel?podo e comprimento do gonop?dio. Amostras do sedimento foram coletadas nas tr?s ?reas para determinar a composi??o granulom?trica. Foi coletado um total de 529 indiv?duos no per?odo de estudo, dos quais 89 eram machos, 97 f?meas n?o ov?geras, 16 f?meas ov?geras e 327 juvenis. Quanto ? estrutura populacional, a distribui??o de frequ?ncia em machos e f?meas foi unimodal. O tamanho m?dio da LC dos machos foi de 4,97 ? 1,53 mm e das f?meas de 5,64 ? 1,73 mm. A an?lise de compara??o do tamanho entre os sexos demonstrou que as f?meas s?o significativamente maiores (U= 23741,5; p< 0,001) em rela??o aos machos. A propor??o sexual da popula??o foi de 1,94:1 (M:F), com predomin?ncia de machos. Na distribui??o espacial, houve maior abund?ncia de animais na ?rea 2, onde a predomin?ncia de juvenis, f?meas ov?geras e f?meas n?o ov?geras foi superior em rela??o ?s outras ?reas. O tamanho m?dio das f?meas ov?geras foi de 6,67 ? 0,60 mm, variando de 5,38 a 7,70 mm. A fecundidade m?dia foi de 424 ? 186 ovos, com uma amplitude de 211 a 886 ovos. O tamanho m?dio dos ovos foi de 0,292 ? 0,011 mm, com uma amplitude de 0,27 a 0,30 mm. O pico de recrutamento ocorreu no m?s de abril. A maturidade morfol?gica das f?meas foi estimada para o tamanho de 5,0 mm e dos machos de 5,9 mm de LC. Conclui-se, que a popula??o de U. victoriana do manguezal estudado demonstrou ser est?vel, apresentando juvenis durante todos os meses. A distribui??o de U. victoriana n?o foi influenciada pela temperatura e granulometria, sugerindo que outros fatores como a abund?ncia de ?rvores ou fatores bi?ticos podem estar influenciando sua distribui??o neste manguezal. A fecundidade encontrada nesta popula??o se correlaciona com o tamanho das f?meas, como ocorre na maioria dos braqui?ros. O per?odo reprodutivo foi sazonal, com maior frequ?ncia de f?meas ov?geras nos meses de setembro e outubro.
7

Biologia reprodutiva do camarão Processa hemphilli Manning & Chace, 1971 (Caridea : Processidae) na enseada de Ubatuba, SP, Brasil /

Talamonte, Natália Bosco January 2020 (has links)
Orientador: Rogério Caetano da Costa / Resumo: O crescimento relativo, a maturidade sexual morfológica e funcional, a fecundidade, o investimento reprodutivo e a razão sexual de Processa hemphilli foram investigados. Testou-se também, a relação de tais aspectos reprodutivos com fatores abióticos como temperatura e salinidade da água de fundo, teor de matéria orgânica e phi. Os camarões foram coletados sazonalmente, do outono de 2016 até o outono de 2019 na Enseada de Ubatuba, litoral norte paulista, por meio de arrastos com uma rede “mini ottertrawl”. Para analisar os fatores abióticos, a água de fundo foi coletada através de uma garrafa de Van Dorn e o sedimento, com um pegador de Van Veen. Os indivíduos foram identificados quanto ao sexo e para as análises do crescimento relativo as seguintes estruturas foram mensuradas (mm): comprimento da carapaça (CC), comprimento do própodo (Pp), carpo (Cp) e mero (Mp) do primeiro (1) e do segundo (2) par de pereópodos, largura da segunda pleura abdominal (2Pl), comprimento do apêndice interno (AI) nos machos e fêmeas, e quanto ao comprimento do apêndice masculino (AM) nos machos. As relações que melhor evidenciaram mudanças na taxa de crescimento entre jovens e adultos, apontando a maturidade sexual morfológica foram: CC x Cp2 nos machos CC x 2Pl nas fêmeas, com maturidade sexual estimada em 3,2 e 3,6 mm CC para machos e fêmeas respectivamente. A maturidade sexual funcional encontrada foi de 3,3 mm CC. A fecundidade média estimada foi de 256,22 ± 134,62 com correlação positiva entr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The relative growth, morphological and functional sexual maturity, fertility, reproductive investment and sex ratio of Processa hemphilli were investigated. It was also tested, a relation of reproductive aspects with abiotic factors like temperature and salinity of the bottom water, content of organic matter and phi. Shrimps were collected seasonally, from autumn 2016 to autumn 2019 in the Ubatuba Bay, north of São Paulo, in trawls with a “mini otter-trawl” net. To analyze abiotic factors, the bottom water was collected using a Van-Dorn bottle and sediment, with a Van-Veen tracker. The individuals were identified according to sex and for the analysis of relative growth, the following structures were measured (mm): carapace length (CL), length of the propodus (Pl), carpus (Cl) and mere (Ml) of the first (1 ) and the second (2) pair of pereopods, width of the second abdominal pleura (2Pl), length of the internal appendage (IA) in males and females, and as for the length of the male appendix (MA) in males. The relationships that best evidenced changes in the growth rate between young population and adults, pointing to the morphological sexual maturity were: CC x Cp2 in males CC x 2Pl in females, with sexual maturity estimated at 3.2 and 3.6 mm CC for males and females respectively. The functional sexual maturity found was 3.3 mm CL. The estimated average fertility was 256.22 ± 134.62 with a positive correlation between the number of eggs and the length of the carapace, indicatin... (Complete abstract click electronic access below) / Mestre
8

Priority effects in Swedish plants, a greenhouse experiment : First come, first served? / Prioriterings effekter hos svenska växter, ett växthus experiment : Först till kvarn?

Tjäder, Jessica January 2022 (has links)
The arrival order of species, also known as priority effects, can have big impacts on the future plant community assembly and diversity. Knowledge about priority effects can be of importance in grassland restoration and to counteract invasive species invasion. The aim of this study was to evaluate if and how much plant traits change with arrival order. Here, 15 grassland species, divided into functional groups (forbs, grasses, and legumes) were sown in a greenhouse. The plants were subject to one of three treatments: ‘Control Alone’ (CA), where each plant was grown alone, ‘Control Together’ (CT), where two plants arrived at the same time and ‘Priority effect’ where the first plant (PE.1) arrived three weeks before the second plant (PE.2). For plants grown alone, there was significant differences between the functional groups for the traits mass relative growth rate, height relative growth rate, plant height, plant width and width of stolons. Forbs had significantly largest relative growth rate (RGR), smallest height after three and six weeks of growth as well as largest stolons at both times. Grasses showed significant largest width at three weeks of growth and legumes reached about the same width as grasses after six weeks of growth. The plants that arrived second showed significantly less growth compared to the other treatments which imply that priority effects occurred. The growth strategy for forbs was fast RGR and production of stolons, for grasses it was primarily an increased width and for legumes it was a combination of reaching large height and width.
9

Assessing Mycorrhizal Growth Rate Across Wild Helianthus Species

Santoni, Alexa D 01 January 2023 (has links) (PDF)
Arbuscular mycorrhizal fungi (AMF) are a category of fungi that occupy virtually all of the Earth's soils. Their role as plant symbionts for nearly all land plants is well documented, where these fungi forms partnerships with plants through the root system. These relationships vary from mutualistic to parasitic and allow the exchange of nutrients between the partners via fungal hyphae that penetrate the cell walls of roots. However, many details of the nature of this symbiosis are not well understood, and the interaction between plants and AMF has been the subject of increased interest recently given the potential benefit to farming systems and natural ecosystems. This study evaluated the variability of mycorrhizal growth response (MGR) to inoculation by the common AMF species Rhizophagus intraradices in a diverse set of wild sunflower species (Helianthus), focusing on how changes in plant traits due to fungal colonization may determine the relative cost or benefit of AMF partnership for wild plants. Results indicate that the overall impacts of AMF colonization on plant growth rate are small, though MGR is correlated with AMF-driven shifts in leaf chlorophyll content. These findings suggest that relative changes in plant growth rate that result from AMF partnership are mediated by plant functional trait.
10

Impact of Weed Control and Fertilization on Growth of Eastern White, Loblolly, Shortleaf, and Virginia Pine Plantations in the Virginia Piedmont

Amishev, Dzhamal Y. 28 September 2005 (has links)
The relative growth response of planted loblolly (Pinus taeda L.), shortleaf (Pinus echinata Mill.), Virginia (Pinus virginiana Mill.), and Eastern white (Pinus strobus L.) pines to intensive silvicultural practices such as woody competition control and fertilization in the Piedmont Province of Virginia is unclear. To address this issue, during 1999, a mixed stand of Virginia pine and hardwoods was clearcut and site-prepared by herbicide application. Three replications containing strips of loblolly, shortleaf, Virginia, and white pines were planted at a 3 m x 1.5 m spacing during February-June, 2000. Four different sources of loblolly pine seedlings were used. The strips were subsequently split across to accommodate four different silvicultural treatments: (1) check (no treatment); (2) woody vegetation control; (3) fertilization; and (4) weed control plus fertilization. The weed control treatment used two directed spray herbicide applications in 2001 (triclopyr and glyphosate) and 2003 (glyphosate) and one mechanical cutting of the remaining hardwoods in 2004. Fertilizer containing N, P, K, and S was applied in 2001, only N in 2002, and N plus P in 2004. Crop tree survival was highest for loblolly pine, decreased in shortleaf and Virginia pines, and Eastern white pine had the poorest survival through age 5. Fertilization without controlling the competing hardwoods decreased survival in all planted pines due to the increased hardwood competition. Loblolly pine was tallest (4.7 m) through the five-year period, shortleaf and Virginia pines were shorter (2.95 m and 3.06 m, respectively), and white pine was shortest (1.7 m). When fertilized, hardwoods were taller than white pine seedlings, almost equal in height to shortleaf and Virginia pines, but shorter than loblolly pine seedlings. Silvicultural treatments had no significant impact on tree height. However, the weed control treatment increased fifth-year pine DBH and stem volume, while fertilization did not. When applied in combination with weed control, there was no additional increase in crop tree DBH and stem volume due to fertilization beyond that from weed control only. The increased availability of soil nutrients due to harvesting the previous stands and allocating them to the crop trees by controlling the competing woody vegetation was enough to meet the nutrient requirements of the young seedlings up to this age. / Master of Science

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