Thesis (Ph.D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [101-116).

Slash and burn shifting (Chitemene) cultivation has been the dominant traditional land use system in the Miombo woodlands of Northern Zambia. The land use system adopted by farmers depends on the interaction between biophysical and socio- cultural and economical resources available to them. Socio economic resources also include policies, which influence the farmers’ decisions. Despite the so many interventions that have been done and condemnation of this system, this practice of cultivation still persist up to today. It is estimated that Northern Province has lost 35% of its biomass, representing about 43000 km2 of forests land over the past 40 years. The continuation of Chitemene system is in the long term unsustainable. This is because if the rural population continues to grow and if the current trend in Chitemenecontinues, complete deforestation may occur in a few decades. This study tried to investigate the factors that determine this practice in Zambia. The study employed a binomial logit model in order to identify the factors that influence the farmers’ decision to practice chitemene and to quantify the relative importance of these factors. This was employed on data collected from a survey of 90 farmers from Kasama district in the Northern Province of Zambia.</p.> It was hypothesized that the farmers’ behavior is influenced by a complex set of socio economic, demographic, technical, institutional and biophysical factors. Some of the determinants of slash and burn practice found in studies done are structural adjustment programme in Zambia, population growth land tenure system, infrastructure, necessary support services, number of household members, age, gender, education level and amount of available land. It was also hypothesized that the traditional way of life of the people has more influence on the farmers’ decision to practice slash and burn than other factors such as land tenure and even availability of agricultural inputs. This is because despite the so many interventions the practice has continued. Also the older the farmer is in his farming practice and age the more likely he is to practice chitemene. The reason is that farmers usually base their practice on experience and older farmers are a bit conservative and often tend to perpetuate the practice. The other one was that farmers with bigger land area are more likely to practice chitemene than those with less total land area. Farmers with bigger land area have more woodland and therefore more likely to practice. The study revealed from the bivariate analysis results that availability of land increases the chances of the farmer practicing chitemene. It was also shown that non-availability of credit influences farmers’ decision to practice chitemene positively. Lack of money to acquire inputs contributed more to farmers’ decision to practice chitemene. In the econometric analysis, age of the farmer, effect of non-availability of credit facility, effect of household size and influence of tradition had a significant influence on chitemene practice. It was found that the main reason for chitemene practice is lack of money for acquisition of inputs. Policies that facilitate provision of credit and infrastructure development like roads are necessary if slash and burn is to be reduced. This study identified some entry points for policy. Poverty may prevent poor farmers from investing in land conservation due to imperfections in credit markets and high subsistence requirements. So unless the government employs policies that target these factors, there is every reason for the farmers to continue the practice of slash and burn. This study brings to light that practicing of Chitemene depends upon a number of factors that dictate its continued practice. It is imperative that the policy makers and all those involved in agricultural development and policy formulation understand these factors and their relative importance in order to have targeted policies. Moreover although a number of studies have been done on slash and burn and its effects in Zambia, these studies have not analysed the significance of these factors. This study has considered this. Apart from this, it has also contributed to the bulk of research literature on chitemene that might be relevant for future research. / Dissertation (MSc (Agricultural Economics))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

With increasing encroachment on natural communities by anthropogenic activity, it is important to understand the functions of natural ecosystems in an effort to conserve natural areas. A first-hand study of the population dynamics of South Florida Slash Pine (P. elliottii Engelm. var. densa) following a fire event provided insight to its recovery and dispersal following a fire. A natural fire (lightning-induced) occurred in the spring of 2000 at the T. Mabry Carlton, Jr. Reserve, Sarasota County, providing an opportunity to study aspects of slash pine in relation to fire. One objective of my research was to look at dispersal/recruitment conditions and slash pine dynamics in relation to fire. I looked at the varying degrees of tree mortality due to fire at different stands of slash pines. I also looked at the stands in terms of stand composition and spatial arrangement of surviving adults. Finally, I studied how variable seedling establishment and survival was between stands. Few inferences could be drawn between fire and these individual analyses; however, all analyses revealed that at the scale of this study, pine flatwoods are patchy. I also looked at the dispersal of slash pines following a fire event. I modeled my research after Ribbens et al. (1994) and Clark et al. (1998), who took a phenomenological approach to dispersal modeling. This approach involved using distances between adults and seeds/seedlings and fecundity of adults to create dispersal models based on maximum likelihood estimates (MLE). I found that, while I could predict a model within acceptable parameters for most of the stands, more data was needed to predict models that better fit the data. This finding, along with the fact that I recovered no seed data for analysis, suggests factors are contributing to dispersal and recruitment (e.g. cone-crop) that need to be accounted for in the future.

A study was conducted at the Savannah River Site near Aiken, SC to: 1) characterize the spatial patterns of soil and forest floor variables (moisture, pH, soil phosphate, forest floor and soil carbon and nitrogen, and soil available nitrogen), 2) assess the spatial patterns of the plant community, and 3) investigate spatial relationships among the variables and between the variables and woody vegetation. Spatial soil and litter samples were collected on five 0.25 hectare plots, and relationships were explored using Pearson's correlation tests, canonical correlation analysis, variogram modeling and kriging. The average range of spatial autocorrelation for the forest floor variables was >45 m, while that for soil variables was 12 m. Woody stem basal area exhibited spatial autocorrelation at ranges of less than 12 m, and was only weakly correlated with forest floor and soil resource patterns. Few strong spatial correlations among the forest floor and soil variables were observed. The means and variances of the variables were low, and differences in resource levels probably had little impact on the spatial pattern of vegetation. Results indicate a weak, differential effect of species group on litter quality, a weak relationship between large pine trees and soil nitrogen patterns, and a general homogeneity of the stands. / Master of Science

Title from PDF of title page. / Document formatted into pages; contains 78 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: With increasing encroachment on natural communities by anthropogenic activity, it is important to understand the functions of natural ecosystems in an effort to conserve natural areas. A first-hand study of the population dynamics of South Florida Slash Pine (P. elliottii Engelm. var. densa) following a fire event provided insight to its recovery and dispersal following a fire. A natural fire (lightning-induced) occurred in the spring of 2000 at the T. Mabry Carlton, Jr. Reserve, Sarasota County, providing an opportunity to study aspects of slash pine in relation to fire. One objective of my research was to look at dispersal/recruitment conditions and slash pine dynamics in relation to fire. I looked at the varying degrees of tree mortality due to fire at different stands of slash pines. / ABSTRACT: I also looked at the stands in terms of stand composition and spatial arrangement of surviving adults. Finally, I studied how variable seedling establishment and survival was between stands. Few inferences could be drawn between fire and these individual analyses; however, all analyses revealed that at the scale of this study, pine flatwoods are patchy. I also looked at the dispersal of slash pines following a fire event. I modeled my research after Ribbens et al. (1994) and Clark et al. (1998), who took a phenomenological approach to dispersal modeling. This approach involved using distances between adults and seeds/seedlings and fecundity of adults to create dispersal models based on maximum likelihood estimates (MLE). I found that, while I could predict a model within acceptable parameters for most of the stands, more data was needed to predict models that better fit the data. / ABSTRACT: This finding, along with the fact that I recovered no seed data for analysis, suggests factors are contributing to dispersal and recruitment (e.g. cone-crop) that need to be accounted for in the future. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 96-107). Also available on the World Wide Web.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2017-09-25T18:57:03Z No. of bitstreams: 1 Regiane_Fagundes2017.pdf: 6331934 bytes, checksum: faab7007f3c7c2e91c6bf26bc30fea8e (MD5) / Made available in DSpace on 2017-09-25T18:57:03Z (GMT). No. of bitstreams: 1 Regiane_Fagundes2017.pdf: 6331934 bytes, checksum: faab7007f3c7c2e91c6bf26bc30fea8e (MD5) Previous issue date: 2017-01-17 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná (FA) / This study aimed at a discussing problems of multivariate statistical inference and linear spatial modeling when observations are from a continuous, symmetric population, with multivariate slash distribution. Firstly, a reparametrization of slash distribution was performed, assuming the existence of the finite second moment. Thus, some iterant properties were shown. Analytical expressions were tested for the score function and Fisher information matrix of reparameterized distribution. An approach to estimate some parameters by maximum likelihood was considered based at the EM (Expectation-Maximization) algorithm. Linear hypothesis tests have been described regarding the means vector and the covariance matrix using statistics such as C(α), likelihood ratio, Wald, and score. Studies of simulation were carried out to evaluate the efficiency of the statistical tests and EM algorithm. Data related to the agricultural area illustrated the methodology developed, and the hypothesis tests for equality of means, sphericity and equicorrelation were also applied. A slash linear spatial model, with and without the use of covariates, was proposed. Were Discussed the global and local influence diagnostic analysis in order to evaluate the influence of observations on the process of parameters’estimation. The curvatures required for the local influence procedure and based on the slash model were derived, in which the perturbation scheme has been chosen properly and related to the different perturbation schemes. Spatial variability maps of chemical attributes of soil and yield were generated by kriging with external drift. Finally results of simulations and applications indicated that the slash distribution is a robust alternative when the data present high kurtosis. / O objetivo deste trabalho foi discutir problemas de inferência estatística multivariada e de modelagem espacial quando as observações são provenientes de uma população contínua, simétrica, com distribuição slash multivariada. Inicialmente, foi realizada uma reparametrização da distribuição slash supondo existência do segundo momento finito, sendo apresentadas algumas propriedades recorrentes. Provaram-se expressões analíticas para a função escore e matriz de informação de Fisher da distribuição reparametrizada. Abordou-se um enfoque para a estimação dos parâmetros por máxima verossimilhança considerando um algoritmo do tipo EM (Esperança-Maximização). Descreveu-se a prova de hipóteses lineares sob o vetor de médias e matriz de covariância com o uso das estatísticas C(α), razão de verossimilhança, Wald e score. Estudos de simulação foram realizados para avaliar a eficiência dos testes estatísticos e do algoritmo EM. Dados relacionados à área agrícola ilustraram a metodologia desenvolvida, sendo aplicado sobre os mesmos os testes de igualdade de médias, esfericidade e equicorrelação. Como ilustração da aplicação da distribuição slash multivariada na área de modelagem estatística, o modelo espacial linear slash, com e sem o uso de covariáveis, foi discutido e proposto. Com o intuito de avaliar a influência das observações no processo de estimação dos parâmetros, discussões relacionadas à análise de diagnóstico, global e local, foram apresentadas. Derivaram-se as curvaturas requeridas no procedimento de influência local para o modelo slash, adequando o esquema de perturbação a distribuição e considerando diferentes esquemas de perturbação. Mapas de variabilidade espacial de atributos químicos do solo e produtividade foram gerados utilizando krigagem com drift externo. Os resultados das simulações e aplicações indicaram que a distribuição slash é uma alternativa robusta quando os dados apresentam alta curtose.

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The history of land utilization in Scandinavia is characterized by two major periods of open landscape. The first one temporal ranged from cal. AD 0-500 and the second one ranged from cal. AD 1200-1900 including the medieval crisis in Scandinavia. Both periods were characterized by animal husbandry and intensive grazing as well as cultivation. However, slash-and-burn-cultivation and hay production on mires and meadows were prevailing during the medieval crisis. These activities significantly altered the concentration of transported organic carbon (OC) from the terrestrial ecosystem to inland waters. Burning and grazing decreased the terrestrial OC and water table, due to reduction of biomass, whereby burning has a greater effect. Biennial scything of mires for hay production reduced the biomass as well, hence resulting in a decreasing water table and peat accumulation. Even though two periods of open landscape has been present in the historical land utilization of Scandinavia, only the latest one resulted in a decreasing OC concentration in surface water in boreal lake. This indicates that especially the slash-and-burn cultivation and hay production on mires are very important components of altering the carbon storage in soils and peat due to lowering the terrestrial OC pool.

South Florida slash pine (Pinus elliottii var. densa) is the southernmost pine species in the United States and the foundation species of the globally endangered pine rockland communities in south Florida. To test if slash pine produces annual growth rings in the Lower Florida Keys, we counted the number of rings on samples collected from the North Big Pine Key site (NBP), which contained a fire scar from a known wildfire and a known date for hurricane-induced tree mortality (2006 or 2007). In addition, a crossdated tree-ring chronology (1871–2009) was developed from living trees and remnant wood found at the site and compared to divisional climate data to determine how the regional climate regime influences radial growth. Our analyses demonstrated that slash pine forms anatomically distinct, annual growth rings with the consistent year-to-year variability necessary for rigorous dendrochronological studies. Response-function and correlation analysis showed that annual growth of slash pine at NBP is primarily influenced by water availability during the growing season. However, no significant correlations were found between tree growth and the Atlantic Multidecadal Oscillation or the El Niño-Southern Oscillation. Our study reveals the potential of producing high-quality dendrochronological data in southern Florida from slash pine, which should prove useful in further studies on fire history and tree phenology and for assessing the projected impacts of impending climate change on the fragile pine rockland community.