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No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Eduarda_Gabriela_Santos_Cunha.pdf: 1983745 bytes, checksum: d73e76b249ad6c1b32a34d0755d35679 (MD5) Previous issue date: 2015 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / RESUMO CUNHA, E. G. S. Quantifica??o de biomassa em floresta estacional semidecidual por meio de redes neurais artificiais. 2015. 77 p. (Disserta??o ? Ci?ncia Florestal) ? Universidade Florestal dos Vales do Jequitinhonha e Mucuri, Diamantina, 2015. A predi??o de biomassa em florestas naturais ? complexa devido ? varia??o de esp?cies, de est?gio sucessional, caracter?sticas ed?ficas e clim?ticas das ?reas, dentre outras, e isso gera uma grande demanda de informa??es para que se tenha estimativas de biomassa confi?veis. O objetivo deste estudo foi de quantificar a biomassa arb?rea a?rea de um fragmento de floresta Estacional Semidecidual em Minas Gerais - MG por meio de redes neurais artificiais (RNA). Assim como, avaliar a influ?ncia das vari?veis categ?ricas fitofisionomia (FT), infesta??o de cip? (CP), qualidade de copa (QC) e coeficiente de De Liocourt (q) na estimativa de biomassa. Foi empregada a t?cnica de valida??o cruzada (cross-validation) para defini??o da topologia e valida??o das redes, em que a estimativa de erro global ? calculada como a m?dia das k estimativas de erro de cada itera??o (admitiu-se k=10).Variou-se o n?mero de neur?nios na camada escondida e avaliou-se a m?dia e o desvio padr?o do erro m?dio quadr?tico (EMQ) dos resultados da valida??o cruzada para definir o n?mero de neur?nios na camada escondida, que melhor se adequou ao problema. Para definir a RNA mais adequada para cada situa??o, uma nova valida??o cruzada foi realizada e avalia??o se deu pelos ajustes das RNA (EMQ, ? ,Bias e Vari?ncia) e an?lise gr?fica dos res?duos. A biomassa observada m?dia foi de 110,81 t.ha-1 e a biomassa m?dia estocada por hectare foi estimada em 114,41 t.ha-1 pela RNA 3 e 116,34 t.ha-1 pela RNA 7. As RNA 3(vari?veis de entrada: DAP, d, Hf, Vt, CP) e 7(vari?veis de entrada: DAP, d, Ht, Vt, CP, QC) se ajustaram melhor, obtendo menores res?duos. No entanto, a RNA 7 que cont?m CP e QC associadas como vari?vel de entrada da rede, teve bom desempenho devido ? contribui??o da vari?vel CP, visto que a RNA 4 que cont?m apenas QC n?o foi precisa na maioria das parcelas, esse fato pode estar relacionado a maior subjetividade na avalia??o da qualidade de copa. A RNA 3 foi mais adequada visando simplicidade na coleta de campo, acarretando menor tempo e custo. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015. / ABSTRACT CUNHA, E. G. S. Biomass quantification in semideciduous forest through artificial neural networks. 2015. 77 p. (Disserta??o ? Ci?ncia Florestal) ? Universidade Florestal dos Vales do Jequitinhonha e Mucuri, Diamantina, 2015. The prediction of biomass in natural forests is complex due to the variation of species in successional stages, characteristics of soil and climate of areas, among other things, and this generates a large demand for information in order to produce reliable biomass estimates. This study aimed to quantify the aerial tree biomass from a fragment of semideciduous forest in Minas Gerais - MG through artificial neural networks (ANN). Moreover, this study evaluated the influence of categorical variables including phytophysiognomy, vine infestation, canopy quality and the De Liocourt quotient in estimation of biomass. All the analysis was done using R software, using the cross-validation technique to define the topology and validation of networks, wherein the global error estimate is calculated as the average of k error estimates of each iteration (assuming k = 10). The number of neurons in the hidden layer varied, and the mean and standard deviation of the mean square error (MSE) were evaluated by the results of cross-validation in order to determine the number of neurons in the hidden layer, which best adapted to the problem. To determine the most appropriate ANN in each situation, a new cross-validation was conducted and the evaluation was completed using the results of the ANN (MSE, Correlation coefficient, Bias and Variance) and graphical residue analysis. The average observed biomass was 110.81 t.ha-1 and the average stored biomass per hectare was estimated to be 114.41 t.ha-1 using ANN 3 and 116.34 t.ha-1 using 7 ANN. This study found that the ANN 3 (input: DAP, d, Hf, Vt, CP) and 7(input: DAP, d, Ht, Vt, CP, QC) had greater precision than the other ANNs, obtaining smaller residue. However, due to the association of vine infestation and crown quality in ANN 7 as input variable network, the good performance possibly because of the variable contribution of the vine infestation, whereas ANN 4 which contains only canopy quality was not more accurate in the majority of plots, this may be related to greater subjectivity in assessing the canopy quality, and in this way. ANN 3 was more appropriate in terms of simplifying field sampling, leading to reduced time and cost.

No description available.

No description available.

This study attempts to explain the inability of resource constrained farmers in Zambia to invest in soil fertility enhancing improved fallows, a sustainable land use practice developed by the World Agroforestry Centre (ICRAF) in the 1980s. Although several studies in the laboratory and field have shown that improved fallows positively impact on farmers’ welfare, the reliability of such conclusions comes into question given their use of improper identification strategies. Secondly, although there is general consensus that improved fallows additionally co-produce environmental services, the literature acknowledges that such services are not only imprecisely defined but also rarely quantified. Most estimates for environmental services have been confined to controlled field trials and laboratory experiments. Consequently, this research was designed to answer the following questions: 1) Would the use of randomisation procedures to estimate impact provide additional support to the foregone conclusions by most literature regarding the positive impact of improved fallows on farmer welfare? 2) Studies from on-station experiments show that improved fallows provide environmental services; do such conclusions hold for improved fallows planted on-farm where the near ideal experimental conditions are not guaranteed? A structured questionnaire was used to interview 324 randomly selected small scale farmers in Chongwe district of Zambia between November and December 2011. The data was analysed using well-grounded and robust matching and switching regression counter factual analysis tools. The rigorous econometric methods confirmed the positive impact of improved fallows on household maize yields, maize productivity, per capita maize yield and maize income. Insignificant impact results were however obtained when broader welfare indicators – overall per capita, crop income and value of crop production were considered. The study attributes these later results to two possible areas; first, most of the maize sold that contributes to crop income may be coming from other input sources such as the inorganic fertiliser that is common in the study area. Second, the non-use of the technology on cash crops (for example cotton) in subsequent periods after a year or two of maize cropping reduces the technology’s contribution to the households’ cash crop income portfolio. Had the study only used maize income or value of maize income to measure overall crop income (or value of crop production), or had it just made a simple comparison between adopters and non adopters, the likelihood of not finding any insignificant results on the efficacy of improved fallows would have been high. The study thus concludes that the use of improved fallows should be diversified to cover the entire cash crop portfolio especially a year or so after maize cropping when most of the nitrogen supplied by technology has been used up. More importantly, the study recommends use of better and more robust methodologies in evaluating impact of interventions. The positive effects of improved fallows on on-farm environmental quality, controlling for farmers’ biophysical and socio-economic characteristics were confirmed. Estimates from OLS regression, matching and the more robust endogenous switching regression showed that the technology had a significant causal effect on households’ consumption of fuel wood obtained from natural forests. The technology can provide up to 1,086 kg or about 51% of annual household fuel wood requirements in the year the fallows are terminated. This amount is substantial enough to make a positive contribution towards reducing encroachment on public forests and thus control the rate of deforestation. In addition to promoting the technology for soil fertility improvement (the role which is widely accepted by the farmers), explicit extension messages conveying the technology’s capacity to provide various products that contribute to farmer welfare as well as provide on farm environmental quality should be made available. / Thesis (PhD)--University of Pretoria, 2014. / lk2014 / Agricultural Economics, Extension and Rural Development / PhD / Unrestricted

Biomass and carbon stock of the natural forests in Vietnam are still not clear due to limitation of knowledge and financial. In this paper, the results of estimating biomass and carbon stocks of the natural forests at Me Linh Biodiversity Station are shown. There are two forest types in this study: the forest vegetation restored after shifting cultivation (vegetation type I) and the forest vegetation restored after clear cutting exploitation (vegetation type II). As the results, the estimated biomass of the forest vegetation restored after shifting cultivation is 86.80 ton.ha-1 and the estimated biomass of the forest vegetation restored after clear cutting exploitation is higher, about 131.59 ton.ha-1. The carbon stock in plants was about 43.40 ton.ha-1 of vegetation type I and 65.79 ton.ha-1 of vegetation type II. The carbon storage in soil of vegetation type I is 79.01 ton.ha-1 and vegetation type II is 99.65 ton.ha-1. Hence, the total of carbon stock in forest vegetation I and II are accounted by 122.41ton.ha-1 and 165.44 ton.ha-1, respectively. In general, it can be pointed out that the naturally recovering secondary forest at Me Linh Station is the secondary young forest with the low economic value due to shortly restored process (about 10-20 years), the flora is not rich and abundant, and there are only commonly pioneer and light demanding tree species. / Sinh khối và trữ lượng các bon của rừng tự nhiên ở Việt Nam vẫn ít được quan tâm của do hạn chế về kiến thức và tài chính. Trong bài báo này, chúng tôi đưa ra kết quả của việc ước lượng sinh khối và tổng hợp các bon của các thảm thực vật rừng thứ sinh phục hồi tự nhiên tại Trạm Đa dạng Sinh học Mê Linh, tỉnh Vĩnh Phúc- Việt Nam, nơi có loại hình thảm thực vật chính, đó là thảm thực vật phục hồi sau nương rẫy (kiểu thảm thục vật I) và thảm thực vật phục hồi sau khai thác kiệt (kiểu thảm thực vật II) nhằm mục đích đánh giá tiềm năng của rừng thứ sinh tại khu vực nghiên cứu. Sinh khối của thảm thực vật phục hồi sau nương rẫy là 86,80 tấn/ha. Sinh khối của thảm thực vật phục hồi sau khai thác cao hơn, đạt 131.59 tấn/ha. Lượng các bon hấp thu trong đất của thảm thực vật I là 79,01 tấn/ha và thảm thực vật II là 99,65 tấn/ha. Như vậy, tổng lượng các bon được hấp thu trong mỗi loại hình thảm thực vật trên là: 122,41 tấn/ha (thảm thực vật I) và 165,14 tấn/ha. Nhìn chung, rừng thứ sinh phục hồi tự nhiên tại Trạm Đa dạng Mê Linh chủ yếu là rừng non thứ sinh, ít có giá trị kinh tế do quá trình phục hồi diễn ra ngắn (khoảng 10-20 năm) nên thành phần thực vật nghèo nàn, không phong phú, thành phần chính chủ yếu là các cây gỗ tiên phong, ưa sáng.

The present study was conducted in Umfakarin natural forest reserve, South Kordofan, Sudan. The main objective was to investigate the possibility of managing Acacia seyal Del. variety seyal for the production of gum talha. Three stand densities (strata), namely dense, medium, and slight, were distinguished based on the number of trees per hectare. During the sampling phase, the study adopted the method of identifying the competitors (neighboring trees) from the subject one (trees selected for gum production experiments). From the three stand densities, a total of 482 subject trees, covering variable diameter ranges (d= 9-11.5, 13.5-16, 18-20.5 and above 21 cm) were selected, based on the diameter at 0.25 m height (d0.25). In each stratum, competitor trees were identified within a radius equal to the height of subject tree multiplied by a factor (1.25). The diameter at breast height, height to crown base, height, crown radii, and tree coordinates were measured for each of the subject trees and its competitors. Subject trees were exposed to tapping on first of October, the fifteenth of October, and the first of November, using local tools (Sonki and Makmak). Additionally, untapped trees were used as controlling-variables. The initial gum collection was completed fifteen days after the tapping, while the subsequent (7-9 pickings) were done at an interval of fifteen days. Six stand height functions were tested and the results illustrated that the Michailow stand height function was suitable for predicting the height of Acacia seyal in Umfakarin natural forest. The predictive ability of this height function ranged from 19.3% to 24%. The volume function used in this study was able to predict the volume of standing trees with more than 92 percent accuracy. Competition among trees of Acacia seyal was assessed in terms of competition indices. Eight competition indices were quantified using the CroCom program. The relationship between these indices and tree dimensions (diameter at breast height, height and crown diameter) was tested using logarithmic models. Among these indices, the Hegyi_2 index is considered a suitable index to be applied for estimating the degree of competition in natural stands of A. seyal of dense stratum when using diameter at breast height as a predictor. About 70% of the total variability is explained by this logarithmic model. Gum yielded by each subject tree per season was obtained by summing up the gum samples collected from all pickings. Gum production per unit area was also determined. Regression tree, general linear model (GLM) and logistic regression techniques were used for analyzing the obtained data. The results of the study indicated that the gum yield is independent of stand density. Tapping has influence on gum yield. Trees tapped by sonki on the first of October at medium stand density have the highest gum with an average value of about 56 g/tree/season. Significant difference (p = 0.021) was detected between two groups of dates; the first of October and first of November in medium stand density. The results also revealed that the most important variable influencing gum production was found to be diameter at breast height with 23.95 cm threshold. Between 41-53 percent of subject trees produce gum less than 50 g/season. The results indicated that A. seyal species produces a very low quantity of gum talha (3.6-4.8 kg/ha) and for economic reasons, its tapping is not recommended. The findings of the regression analysis revealed to a model which could be used to estimate the yield of gum talha from A. seyal natural stands in the Umfakarin forest, South Kordofan, Sudan. Conducting experiments on the production of gum talha in permanent plot trials in different climatic regions of the Sudan is highly recommended.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lianas are known as forest parasites, although they are major components structurally and floristically of natural forests. The aim of this study was to research liana ecology and its effects on growth and production of Angico-Vermelho. Field procedures were realized in one hectare of natural forest and 50 individual trees. Were found 23 species in the liana community, that strongly dominated by Senegalia tucumanensis. Scramblers and tendril climbers showed a greater capacity of sprouting, being more resistant to liana cutting. Angico-Vermelho has more lianas around it than does the overall forest. Above-ground competiton, measured by COI (Crown Occupancy Index), negatively influenced crown development. Liana basal area helped to explain basal area increment variation in Angico-Vermelho as the overall model explained almost 80% of total variation. Angico-Vermelho has great exploration potential in natural forests due to fast growth, wood quality and carbon sequestration ability. It is recommended, as a silvicultural treatment, liana cutting in trees with less than 20 centimeters of diameter, otherwise in trees with more the 25% of the crown occupied by lianas. / Cipós são conhecidos como pragas florestais, no entanto possuem grande importância florística e estrutural em florestas naturais. O objetivo deste estudo foi conhecer a ecologia de cipós e seu efeito sobre o crescimento e produção do Angico-Vermelho. Foi levantado um hectare de um fragmento da Floresta Estacional Decidual, dentro do qual foram selecionados 50 Angicos- Vermelhos e a comunidade de cipós associados á estes. Foram encontradas 23 espécies de cipós, com forte dominância de Senegalia tucumanensis. Espécies apoiantes e preenseis mostraram maior capacidade de brotação e, portanto, são mais resistentes ao corte. Existiu uma forte influência da bordadura na área basal de cipós. O Angico-vermelho possui mais cipós em seu entorno do que na floresta como um todo. A competição acima do solo por cipós, medida através do IOC (Índice de Ocupação de Copa) influenciou negativamente no desenvolvimento da copa. A área basal de cipós contribuiu na explicação da variação do incremento em área basal do Angico-Vermelho, sendo que o modelo proposto explicou quase 80% da variação. O Angico- Vermelho possui grande potencial de exploração no manejo de florestas naturais devido ao seu rápido crescimento, madeira de qualidade e capacidade de sequestro de carbono. É recomendado como tratamento silvicultural o corte pontual de cipós em indivíduos com menos de 20 centímetros de diâmetro e em árvores com mais de 25% da copa ocupada nos outros casos.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of this study was to determine sample sufficiency for phytosociological studies and inventories of wood in a forest area of Miombo woodland in Mocuba district, Zambezia province, Mozambique. The study area was represented by a systematic sampling grid that contains 128 sampling units ranging from 0.1 to 1.0 ha, inserted into 16 tracks, with eight units in each, arranged randomly and independent of each other. All individuals with Cbh ≥ 31.5 cm were measured and identified. Obtained the parameters of the floristic composition, horizontal structure, diversity using Shannon-Wienner, by the evenness index of Pielou and sampling sufficiency was evaluated based on analysis of curve species/area. The behavior of the diameter distribution curves were fitted to the treatment function Meyer and statistically compared by Chi-square (χ2), adopting α = 5% and was found by analysis of covariance showed that the same level differences and gradients among themselves. The selection of the size of the sampling units was based on the stability of the coefficient of variation in the relative sampling error; the fewer sized sampling units and the practicality of applying the methodology in the field. In the area 36535 individuals distributed, on average occurred in 516.6 ind.ha-1, with a mean basal area of 26.21 m2.ha-1. The richest botanical family was Fabaceae. The most important species was the Brachystegia spiciformis forest showed a high species diversity and evenness. Observed stability curve species/area from 4.0 ha area covered with the occurrence of 86 species. The diameter distribution curves were not adherent by χ2 test for size 0.1 ha and 0.25 ha and covariance analysis showed no difference in slope between level and sizes can use a single regression. The sampling units of 0.25 ha (50m x 20m) had lower sampling errors of 10% in the estimation of basal area for groups of commercial species. The estimated basal area at the species level was found to be not accurate due to the low frequency of individuals per hectare / O objetivo do presente trabalho foi o de determinar a suficiência amostral para estudos fitossociológicos e para estoques de madeira numa área de floresta de Miombo, no distrito de Mocuba, província da Zambézia, Moçambique. A área estudada foi representada por uma grade amostral sistemática que contém 128 unidades amostrais variando de 0,1 a 1,0 ha, inseridas em 16 faixas, com oito unidades em cada, dispostas aleatoriamente e independentes entre si. Todos os indivíduos lenhosos com Cap ≥ 31,5 cm foram medidos e identificados. Obtiveram-se os parâmetros da composição florística, estrutura horizontal, diversidade pelo índice de Shannon-Wienner, a equabilidade pelo índice de Pielou e a suficiência amostral foi avaliada com base na análise da curva espécie/área. O comportamento das curvas de distribuição diamétrica para os tratamentos foram ajustadas pela função de Meyer e comparadas estatisticamente pelo teste de Chi-quadrado (χ2), adotando α=5% e verificou-se, pela análise de covariância, se as mesmas apresentavam diferenças de níveis e inclinações entre si. A seleção do tamanho das unidades amostrais foi baseada na estabilidade do coeficiente de variação, no erro de amostragem relativo, no menor número dimensionado de unidades amostrais e na praticidade da aplicação da metodologia em campo. Na área, ocorreram 36535 indivíduos distribuídos, em média 516,6 ind.ha-1, e com área basal média de 26,21 m2.ha-1. A família botânica mais rica foi a Fabaceae. A espécie mais importante foi a Brachystegia spiciformis e a floresta mostrou-se com alta diversidade de espécie e equabilidade. Observou-se a estabilidade da curva espécie/área a partir de 4,0 ha de área amostrada com a ocorrência de 86 espécies. As curvas de distribuição de diâmetro não se mostraram aderentes pelo teste χ2 para os tamanhos 0,1 ha e 0,25 ha e a análise de covariância não mostrou diferença de inclinação e nível entre os tratamentos podendo-se usar uma única regressão. As unidades amostrais de 0,25 ha (50m x 20m) apresentaram erros de amostragem inferiores a 10% na estimativa de área basal para os grupos de espécies comerciais. A estimativa da área basal em nível de espécie mostrou-se não precisa devido à baixa frequência de indivíduos por hectare.

Economic Valuation of the natural patrimony: Protected Natural AreasThis paper offers some knowledge about the utility of Economic Valuation of Assets out of  market methods, to allow management in general and as a guide to the planning of natural areas with valuable ecologic and landscaping aspects. Here, I show the importance of the Protected Natural Areas (ANP) in the national economy and their economic value. I describe the most used techniques in the valuation of ANPs with special attention to the direct using values through the application of cost of travel and contingent valuation methods.As an example of the use of these techniques, I present the application results at the Private Conservation Area-El Cañoncillo Natural Forest, with the objective to analyze the pertinence of the economic valuation by the adoption of conservation practices. / El presente artículo brinda conocimientos sobre la utilidad de los métodos de valoración económica de los bienes sin mercado, tanto para su gestión en general como para que sirva de guía para la planificación de áreas naturales ecológica y paisajísticamente valiosas en particular. Muestra la importancia de las áreas naturales protegidas (ANP) en la economía nacional y su valoración económica. Se describen las técnicas más usadas en la valoración de las ANP, con especial atención en los valores de uso directo a través de la aplicación de métodos de costo de viaje y de valoración contingente (CVVC).Como ejemplo de uso y potencial de estas técnicas se presentan los resultados de su aplicación en el Área de Conservación Privada Bosque Natural El Cañoncillo, con el objetivo de analizar la viabilidad de la valoración económica por medio de la adopción de prácticas de conservación.

The present study was conducted in Umfakarin natural forest reserve, South Kordofan, Sudan. The main objective was to investigate the possibility of managing Acacia seyal Del. variety seyal for the production of gum talha. Three stand densities (strata), namely dense, medium, and slight, were distinguished based on the number of trees per hectare. During the sampling phase, the study adopted the method of identifying the competitors (neighboring trees) from the subject one (trees selected for gum production experiments). From the three stand densities, a total of 482 subject trees, covering variable diameter ranges (d= 9-11.5, 13.5-16, 18-20.5 and above 21 cm) were selected, based on the diameter at 0.25 m height (d0.25). In each stratum, competitor trees were identified within a radius equal to the height of subject tree multiplied by a factor (1.25). The diameter at breast height, height to crown base, height, crown radii, and tree coordinates were measured for each of the subject trees and its competitors. Subject trees were exposed to tapping on first of October, the fifteenth of October, and the first of November, using local tools (Sonki and Makmak). Additionally, untapped trees were used as controlling-variables. The initial gum collection was completed fifteen days after the tapping, while the subsequent (7-9 pickings) were done at an interval of fifteen days. Six stand height functions were tested and the results illustrated that the Michailow stand height function was suitable for predicting the height of Acacia seyal in Umfakarin natural forest. The predictive ability of this height function ranged from 19.3% to 24%. The volume function used in this study was able to predict the volume of standing trees with more than 92 percent accuracy. Competition among trees of Acacia seyal was assessed in terms of competition indices. Eight competition indices were quantified using the CroCom program. The relationship between these indices and tree dimensions (diameter at breast height, height and crown diameter) was tested using logarithmic models. Among these indices, the Hegyi_2 index is considered a suitable index to be applied for estimating the degree of competition in natural stands of A. seyal of dense stratum when using diameter at breast height as a predictor. About 70% of the total variability is explained by this logarithmic model. Gum yielded by each subject tree per season was obtained by summing up the gum samples collected from all pickings. Gum production per unit area was also determined. Regression tree, general linear model (GLM) and logistic regression techniques were used for analyzing the obtained data. The results of the study indicated that the gum yield is independent of stand density. Tapping has influence on gum yield. Trees tapped by sonki on the first of October at medium stand density have the highest gum with an average value of about 56 g/tree/season. Significant difference (p = 0.021) was detected between two groups of dates; the first of October and first of November in medium stand density. The results also revealed that the most important variable influencing gum production was found to be diameter at breast height with 23.95 cm threshold. Between 41-53 percent of subject trees produce gum less than 50 g/season. The results indicated that A. seyal species produces a very low quantity of gum talha (3.6-4.8 kg/ha) and for economic reasons, its tapping is not recommended. The findings of the regression analysis revealed to a model which could be used to estimate the yield of gum talha from A. seyal natural stands in the Umfakarin forest, South Kordofan, Sudan. Conducting experiments on the production of gum talha in permanent plot trials in different climatic regions of the Sudan is highly recommended.