In recent years, interest in uneven-aged forestry has been increasing in Britain, particularly for sensitive areas such as recreation and amenity forests. Literature on the economics of uneven-aged forestry is scarce and few operational, uneven-aged forests are available for study. Therefore, in order to quantify the operating costs associated with uneven-aged forestry, a modelling approach was chosen. The resulting model is written in FORTRAN and uses a series of square two-dimensional arrays to represent a block of forest. The block may then be managed by clearfelling and replanting at a specified age, or by a system of group management with a choice of four group sizes. The resulting model was then used to investigate the effect of the following management strategies on operating times: 1. Varying the scale of working (i.e. the group size and forest size) in the uneven-aged forest. 2. Using shortwood or pole-length harvesting systems and a range of machine types within each harvesting system. 3. Varying the length of time taken to transform the structure of the forest from even-aged to uneven-aged. 4. Varying the age of the trees when the transformation from even-aged to uneven-aged structure begins. The results obtained from running the model show that the time taken to carry out an operation is influenced both by the absolute size of the group within the forest block and by the number of groups of that size within the forest block. This fragmentation effect explains why it is difficult to determine the absolute costs of working for a specific group size, because it is the combination of group size, number of groups and forest block size, which determines costs. Most of the results below are based on a range of group sizes from 1.000 ha. to 0.0625 ha., with a block size of 16 ha. Forwarders were penalized when the group size was decreased to 0.0625 ha. (-12% increase over clearfelling), because very small groups do not contain full forwarding loads and a large proportion of total forwarding time is spent manoeuvring into and out of groups. However, the operating times for the three group sizes 1.00 ha., 0.25 ha. and O. 1 1 ha. were very similar indicating that the group size can be quite small before any extra forwarding costs are incurred. On poor sites, the cost differential between the largest and smallest groups is greater. In contrast to forwarding, skidders are most penalized with the decision to adopt an uneven-aged system, and once that decision has been made, there is not a clear increase in costs with decreasing group size. During the transformation period, felling and thinning times in the uneven-aged system are significantly higher than those for the even-aged system, because trees are being harvested prematurely to create the early groups, but this difference is reduced once the forest is transformed. Felling and thinning times increase gradually as the group size decreases, because more care is needed for the felling operation and more time is needed for snedding coarse edge trees. Replanting times for the uneven-aged forest are approximately 8% - 14% higher than replanting times for clearfelling. The results from the model were then analysed using the EXCEL spreadsheet programme to examine, among other things, the cost implications of varying group size, and the relative profitability of uneven-aged and even-aged management. First,optimum ages to begin transformation were found, which varied with the Yield Class and discount rate chosen. Then, the effect of the length of the transformation period was examined and a long transformation period (80-years) was found to be preferable to a short transformation period (40-years). The analysis showed that at high discount rates even-aged and uneven-aged management had similar Net Present Values, but at lower discount rates the even-aged system was preferred. The greatest financial penalty was incurred with adoption of an uneven-aged system, and reducing the group size had relatively little impact on Net Present Values. Other costs and benefits, such as scenic beauty and recreation potential, could not be included in the model, because research relating these values to forest management variables has not been carried out. Therefore, these mostly non-financial factors were discussed for even-aged and uneven-aged forestry, based on a review of the literature.

The passage of the Federal Water Pollution Control Act of 1972 required states to develop forestry BMPs to help reduce potential nonpoint source pollution from forest operations. Properly applied forestry best management practices (BMPs) have since been proven to protect water quality from forest operations. This research project reviewed BMP effectiveness studies in the U.S., assessed current state developed and implemented of forestry BMPs, and developed a simple method to estimate potential erosion from forest operations for the Piedmont physiographic region based on previous studies. Eighty-one BMP effectiveness studies were reviewed. The review of past effectiveness studies indicates that water quality protection is increased when BMPs are implemented correctly. These effectiveness studies provide states with valuable information on how their BMP guidelines are achieving the goals defined by the Federal Water Pollution Control Act. Every U.S. state has forestry BMP guidelines. These guidelines may be non-regulatory, quasi-regulatory, or regulatory depending on the state. Twenty states reported implementing non-regulatory BMP guidelines, 19 quasi-regulatory BMP guidelines, and 11 regulatory BMP guidelines. State forestry agencies were reported as being the lead agency responsible for BMP monitoring in 35 states. The national forestry BMP implementation rate was 91% (32 states). However, states did report deficiencies for specific BMP guideline categories. Supplementary to the reviewed BMP effectiveness studies, forest erosion studies in the southeastern U.S. that quantified erosion rates from forest operations were also reviewed. Erosion rates obtained from the literature were reviewed by operation categories (timber harvesting, forest roads, skid trails, log landings, stream crossings, and streamside management zones) and physiographic region (Mountains, Piedmont, Gulf Coastal Plain, and Atlantic Coastal Plain). There were numerous research gaps regarding erosion rates from forest operations for all the regions except the Piedmont region. The Piedmont region was selected for developing a method to estimate potential erosion from forest operations. This erosion estimation method is a quick and potentially useful tool for estimating potential erosion; however, it is based on limited data from the Piedmont region only. The basic method approach might be considered for the other physiographic regions, but further research is needed to fill current knowledge gaps. / Ph. D.

A terceirização e a primarização constituem estratégias de gestão que vem sendo adotadas por empresas florestais brasileiras. Entretanto, apesar de sua crescente utilização, suas diferenças em termos técnicos, econômicos e estratégicos, tais práticas não têm sido objeto de muitos estudos no Brasil, principalmente no que se refere ao setor florestal. Em virtude dessa realidade, o objetivo principal desta pesquisa foi comparar os modelos terceirizados e primarizados dos processos de produção de mudas, formação florestal, colheita e carregamento de madeira, em florestas plantadas, avaliando riscos, oportunidades e recomendando melhores alternativas segundo a percepção ou o ponto de vista dos principais envolvidos, ou seja, a empresa florestal contratante e o prestador de serviços. Para a realização das análises financeiras e de custos dos processos florestais abrangidos no estudo foram utilizadas informações levantadas junto a empresas prestadoras de serviços florestais localizadas no extremo sul da Bahia, cedidas pela Cia Suzano Papel e Celulose, Unidade Mucuri-BA (contratante) e mais outras cotações realizadas com diferentes fornecedores de materiais, mão-de-obra, serviços e insumos. A partir das análises, verificou-se que os processos florestais produção de mudas (com viveiro próprio) e carregamento de madeira, quando terceirizados, apresentaram custo operacional menor do que quando primarizados. Já os processos formação florestal e colheita mecanizada, quando primarizados com a aquisição de máquinas, resultaram em custo operacional menor do que quando terceirizados. Porém, em virtude da necessidade de investimento para aquisição de equipamentos e estruturas, o resultado da análise financeira de todos os processos primarizados tornou-se negativo (VPL < 0). Constatou-se também que os principais fatores contrários à primarização foram: custo com mão-de-obra (significativamente maior para a atividade primarizada), custo com estrutura de apoio e remuneração do capital investido. Já os principais fatores favoráveis à primarização foram: carga de taxas e impostos incidentes sobre o custo do serviço de terceiros e a margem de lucro aplicada pelo prestador de serviço. Ainda que apresente resultados financeiros negativos, a primarização das atividades florestais pode trazer outros benefícios, viabilizando-a estratégica e até economicamente, possibilitando o livre-arbítrio ao administrador quanto à melhor forma de gestão de acordo com a sua realidade e necessidade dentro do mercado. Palavras-chave: Operaçõ / The Outsourcing and the Primarization constitute management strategies been used by Brazilians forest companies. However, although its use is increasing, technical, economics and strategy terms are not being studied in Brazil, mainly on the forestry sector. Therefore, the principal goal on this research was to compare Outsourcing and Primarization Models including the process of seedlings production, forest formation, harvest and loading for planted forest, evaluating risk, opportunity and recommendation about better practices by the perception or point of view of the forest company and the service provider. The database for realize the financial and cost analyses from forest processes came from forest services providers, in the Extreme South of Bahia Estate, and Suzano Pulp and Paper Company (contractor). Seedling production, with own nursery, and wood loading presented lower operational costs when done by services providers. The costs of forest formation and harvest processes, when done by the contractor, including machines acquisition, were lower than the same operations done by services providers. However, because of necessary investment for machinery and structure acquisition, the financial analysis of all primarized processes resulted negative (NPV < 0). The main negative factors were labor cost (significantly higher for primarized activities) and the cost of payment for invested capital. The main factors favoring the primarization were taxes paid by services providers and the profit margin earned by them.

A terceirização e a primarização constituem estratégias de gestão que vem sendo adotadas por empresas florestais brasileiras. Entretanto, apesar de sua crescente utilização, suas diferenças em termos técnicos, econômicos e estratégicos, tais práticas não têm sido objeto de muitos estudos no Brasil, principalmente no que se refere ao setor florestal. Em virtude dessa realidade, o objetivo principal desta pesquisa foi comparar os modelos terceirizados e primarizados dos processos de produção de mudas, formação florestal, colheita e carregamento de madeira, em florestas plantadas, avaliando riscos, oportunidades e recomendando melhores alternativas segundo a percepção ou o ponto de vista dos principais envolvidos, ou seja, a empresa florestal contratante e o prestador de serviços. Para a realização das análises financeiras e de custos dos processos florestais abrangidos no estudo foram utilizadas informações levantadas junto a empresas prestadoras de serviços florestais localizadas no extremo sul da Bahia, cedidas pela Cia Suzano Papel e Celulose, Unidade Mucuri-BA (contratante) e mais outras cotações realizadas com diferentes fornecedores de materiais, mão-de-obra, serviços e insumos. A partir das análises, verificou-se que os processos florestais produção de mudas (com viveiro próprio) e carregamento de madeira, quando terceirizados, apresentaram custo operacional menor do que quando primarizados. Já os processos formação florestal e colheita mecanizada, quando primarizados com a aquisição de máquinas, resultaram em custo operacional menor do que quando terceirizados. Porém, em virtude da necessidade de investimento para aquisição de equipamentos e estruturas, o resultado da análise financeira de todos os processos primarizados tornou-se negativo (VPL < 0). Constatou-se também que os principais fatores contrários à primarização foram: custo com mão-de-obra (significativamente maior para a atividade primarizada), custo com estrutura de apoio e remuneração do capital investido. Já os principais fatores favoráveis à primarização foram: carga de taxas e impostos incidentes sobre o custo do serviço de terceiros e a margem de lucro aplicada pelo prestador de serviço. Ainda que apresente resultados financeiros negativos, a primarização das atividades florestais pode trazer outros benefícios, viabilizando-a estratégica e até economicamente, possibilitando o livre-arbítrio ao administrador quanto à melhor forma de gestão de acordo com a sua realidade e necessidade dentro do mercado. Palavras-chave: Operaçõ / The Outsourcing and the Primarization constitute management strategies been used by Brazilians forest companies. However, although its use is increasing, technical, economics and strategy terms are not being studied in Brazil, mainly on the forestry sector. Therefore, the principal goal on this research was to compare Outsourcing and Primarization Models including the process of seedlings production, forest formation, harvest and loading for planted forest, evaluating risk, opportunity and recommendation about better practices by the perception or point of view of the forest company and the service provider. The database for realize the financial and cost analyses from forest processes came from forest services providers, in the Extreme South of Bahia Estate, and Suzano Pulp and Paper Company (contractor). Seedling production, with own nursery, and wood loading presented lower operational costs when done by services providers. The costs of forest formation and harvest processes, when done by the contractor, including machines acquisition, were lower than the same operations done by services providers. However, because of necessary investment for machinery and structure acquisition, the financial analysis of all primarized processes resulted negative (NPV < 0). The main negative factors were labor cost (significantly higher for primarized activities) and the cost of payment for invested capital. The main factors favoring the primarization were taxes paid by services providers and the profit margin earned by them.

Forestry Best Management Practices (BMPs) include guidelines, recommendations, and protocols utilized to protect forest water quality from nonpoint source pollutants (NPSP). Sediment is the most common NPSP associated with forest operations, and BMPs are implemented primarily to reduce erosion and potential sediment delivery to streams. Skid trails, stream crossings, forest roads, decks, and harvest areas are major forest operational features that have the potential to erode and deliver sediment to streams. These five features are also common BMP categories evaluated by states across the southeastern U.S. Although BMPs are designed to minimize erosion and sediment delivery, the exact relationship between BMP implementation rates, erosion rates, and potential sediment delivery is largely unexamined. Specifically, the inherently intuitive but unverified concept that increasing levels of BMP implementation decreases erosion and sediment delivery associated with forest harvesting. This hypothesis was tested in this project at five operational features located within three physiographic regions, including the Mountains, Piedmont, and Coastal Plain, across clearcut harvest sites in the southeastern U.S. First, BMP implementation rates, audit questionnaires, and state guidelines were compared across 13 states in the southeastern region at 116 clearcut harvest sites. Overall, BMPs were implemented at an average rate of 90.1% in the southeastern United States, thus demonstrating that BMPs are currently being implemented consistently at high levels throughout the region. Across all regions, average BMP implementation rates were highest at harvest areas (95.6%), followed by decks (92.7%), haul roads (91.9%), stream crossings (88.2%), and skid trails (82.9%). Average BMP implementation rates for Mountain stream crossings (83.9%) and skid trails (76.1%) were significantly lower than rates calculated in the Piedmont and Coastal Plain, and had the lowest implementation rate for any feature in any region. These findings indicate that skid trails and stream crossings, especially in the Mountains, may benefit the most from enhanced BMP implementation and resources. In the second manuscript, the relationship between BMP implementation, estimated erosion, and potential sediment delivery were examined in three regions of Virginia and North Carolina. This study is one of the only forestry studies that have presented sediment delivery ratios by operational feature and physiographic region. BMP implementation rates and sediment delivery ratios were poorly correlated, however, a significant inverse relationship existed between BMP implementation and the total sediment mass delivered to streams (Spearman ρ = -0.2206, p-value = 0.0027). Generally, as BMP implementation increased, erosion rates and the amount of sediment delivered to streams also decreased. Additionally, this study demonstrated that most of the erosion generated by clearcutting operations in the southeast is trapped in either the harvest area or in Streamside Management Zones (SMZs) prior to reaching the stream. In the third manuscript, BMP implementation rates and erosion estimates were categorized into three BMP levels (BMP−, BMP-standard, BMP+) which represent low, moderate, and high levels of BMP implementation, respectively. Skid trails and haul roads generally had the highest erosion estimates, regardless of BMP level and physiographic region. Non-parametric correlation analyses indicated that significant inverse relationships existed between BMP implementation rates and erosion estimates at skid trails (Spearman ρ = -0.589, p-value < 0.0001), haul roads (Spearman ρ = -0.388, p-value < 0.0001), and harvest areas (Spearman ρ = -0.2305, p-value = 0.0169), while decks and stream crossings were more poorly correlated with erosion estimates. This reinforces the need for BMP audit questions that specifically address ground cover and bare soil, water control structures, gradients, and stabilization to better address potential erosion and sedimentation. Clearcut areas, erosion and sediment estimates, and sediment removal efficiencies were presented for the Mountains, Middle/Lower Coastal Plain, and Piedmont/Upper Coastal Plain for the fourth, fifth, and sixth manuscripts, respectively. Regardless of BMP level and physiographic region, a combination of harvest areas, skid trails, and haul roads were responsible for over 95% of potential sediment delivery. Increasing site-wide BMP implementation from BMP− to BMP+ could reduce sediment delivery by 70% in all physiographic regions. High levels of BMP implementation were most effective at reducing potential erosion and sediment delivery from skid trails and haul roads throughout the southeast. Findings from these studies demonstrate that current BMPs are highly effective at mitigating sediment. In the southeastern U.S., increasing levels of BMP implementation effectively reduce both potential erosion and sedimentation associated with forest harvesting. Generally, both estimated erosion and sedimentation associated with clearcutting in the region is much lower than rates associated with other land uses such as development or agriculture, especially when BMPs are implemented at standard or high levels. However, several opportunities exist to improve the effectiveness of BMPs in the southeastern U.S. Skid trails, haul roads, and stream crossings consistently had the lowest BMP implementation rates and highest estimated erosion rates and sediment delivery ratios. While these features only represent a small proportion of total clearcut area in the southeast, they are responsible for a disproportionate amount of sediment delivery and should receive more attention and resources during the pre-harvest planning and closure processes. Conclusively, this project addresses several knowledge gaps pertaining to water quality impacts resulting from harvesting operations in the southeastern U.S. For instance, this is only the third project that has presented sediment delivery ratios associated with forest operations in the southeastern U.S., and the first to do so for the Mountains and Coastal Plain regions. On average, SMZs and harvest areas trap 66-96% of sediment on-site before it can be deposited into streams. Additionally, this project provides one of the first and most comprehensive regional comparisons of state BMP manuals, audits, and programs in-field using a third-party approach. Several significant differences existed among state BMP programs and protocol, and states may need to design specific BMP guidelines and audit protocol for major physiographic regions to address the challenges and variation of on-site conditions inherent of each region. Additionally, this project presents one of the only regional-scale estimates of sediment and efficiencies of increased levels of BMP implementation at mitigating sediment associated with forest operations in the southeastern U.S. Conclusively, this project provides forest managers, state and federal agencies, and policymakers with a robust assessment on the effectiveness of forestry BMPs in the southeast. / Doctor of Philosophy / Forestry Best Management Practices (BMPs) are used throughout the southeastern U.S. to minimize the impacts that harvesting has on soil and water resources. Eroded soil that is eventually deposited into streams as sediment is the most important pollutant that BMPs address in forestry. Common BMP guidelines utilized to minimize sediment include leaving riparian buffers along streams, providing ground cover, minimizing slopes on roads, and using water control structures to divert runoff from road systems. The exact relationship between forestry BMPs, erosion, and sediment delivery is largely unexamined. Objectively, this study was designed to provide a better understanding of this relationship, and to present estimates of erosion and sediment delivery resulting from clearcut harvesting on over 100 harvest sites across 13 states with diverse conditions and topography in the southeastern U.S. Forestry BMPs are being implemented at an average rate of 90.1% across the southeast. BMPs are implemented at higher rates in the Coastal Plain, followed by the Piedmont and Mountains. Generally, harvest areas had the highest BMP implementation rates, followed by decks, haul roads, stream crossings, and skid trails, respectively. This relationship was consistent across most regions and states. Logging decks, which are areas where wood was transported for processing and loading onto logging trucks, were generally located distantly from streams and followed most state-approved BMPs. Whereas skid trails, which are low-standard temporary roads trafficked during primary transport and require water diversion structures such as waterbars, occupied a much larger area and were generally located on much steeper slopes. Mountain skid trails leading to stream crossings are concerning because of their low BMP implementation rates and high erosion potential. These features would greatly benefit from increased ground cover and water control structures. Forestry BMPs reduce both erosion and sedimentation associated with clearcutting. The highest level of BMP implementation reduces potential sediment by over 70% in all regions, and the highest BMP level is most effective at reducing sediment from skid trails and forest roads. Average sedimentation rates, especially at the highest BMP level, calculated for Mountains, Piedmont, and Coastal Plain clearcuts are considerably lower than sedimentation rates associated with agricultural and developmental land uses. Clearcut forestland, which is generally the most erodible time period during a forest's cycle, only makes up 1-2% of total forestland in the southeast annually. Both erosion and sedimentation rates should decrease further in the years following harvesting as the site revegetates and trees begin to reestablish. This study verifies that BMPs are highly effective at reducing erosion and sediment while subsequently providing estimates of erosion and sediment delivery based on ranges of BMP implementation that state forestry agencies can use to better quantify the effectiveness of their BMPs.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-12T13:30:05Z No. of bitstreams: 1 PGEF16MA073.pdf: 1558252 bytes, checksum: 078f732c32622d0875732cff37fb28d7 (MD5) / Made available in DSpace on 2017-12-12T13:30:05Z (GMT). No. of bitstreams: 1 PGEF16MA073.pdf: 1558252 bytes, checksum: 078f732c32622d0875732cff37fb28d7 (MD5) Previous issue date: 2016-12-06 / The objective of the present research was to analyze timber extraction operations and determining economically optimal density of forest roads in thinnings and clear cut for Pinus stands managed for multiple use, subsidizing the operations planning for forest sustainability. The survey was conducted in areas of harvest of Pinus taeda L., belonging to Florestal Gateados Ltda, in Campo Belo do Sul, SC. The study was divided into two stages. In the first, a technical analysis, modeling and cost productivity of logging activities in different situations and machines: (a) first thinning in cut to lenght system (CTL) with forwarder; (b) third roughing in CTL system with forwarder; (c) clear cut in with forwarder CTL system; and (d) clear cut in full tree system (FT) with skidder. Technical analysis was performed by means of a time and motion study, with a sampling error of less than 10%, being evaluated the elements of the operating cycle and given nominal productivity (Pn) and effective (Pe). The cost analysis was accomplished through the determination of production and operational costs for the accounting method. The operations were evaluated in different conditions of slope, direction of operation, distance of extraction, presence of rocky outcrop and volume by class tora, which were also regarded as independes variables to fit mathematical models for multiple regression for estimation of productivity, using the Stepwise Procedure. The main results were: for the first trim the Pn was 10,90 m3/h and total operating cost (COT) of R$/he. 181,12 For the third roughing the NP was 16,45 m3/h and COT of 185,58 R$/he. In clear cut, for forwarder if a Pn of 29,05 m3/h and COT of 244,58/he R$, while for the skidder obtained a Pn of 128,60 m3/h and COT of 218,31 R$/he. For the modeling of productivity of machines, the distance and the volume by tora were used as explanatory variables, being present in the estimates for the forwarder, in addition to the volume per cycle, in third, and slope in the first thinning and clear-cutting. For the skidder, the variables used were the distance and volume per cycle. In step two was given the economically optimum density (DOE) and acceptable (DAE) for different situations. The DOE was calculated by the indirect method, which is the product of the sum of the costs of reconstruction, maintenance, extraction and waste of productive area. First trim the current road density (of) was 45,28 m/ha, the DOE of 20,18 m/ha and the DAE of 28,26 m/ha. Third roughing the of was 95,08 m/ha, the DOE of 16,60 m/ha and the DAE of 21,68. In clear-cutting the of was 92,02 w/ha, being the DOE for the CTL system of 15,63 m/ha and DAE of 24,75 m/ha, while in the FT system DOE was 22,85 m/ha and 27,00 m DAE/ha. In General, the density of current roads was above the good and acceptable and should be carried out a redesign of operations targeting a road network within the acceptable density, resulting in lower costs and increased revenue to the company / O objetivo da presente pesquisa foi analisar operações de extração de madeira e determinar economicamente a densidade ótima de estradas florestais em desbastes e corte raso para povoamentos de Pinus manejados para uso múltiplo, subsidiando o planejamento das operações com vistas à sustentabilidade florestal. A pesquisa foi realizada em áreas de colheita de Pinus taeda L., pertencentes à empresa Florestal Gateados Ltda, em Campo Belo do Sul, SC. O estudo foi dividido em duas etapas. Na primeira, foi realizada uma análise técnica, de custos e modelagem da produtividade das atividades de extração de madeira em diferentes situações e máquinas: (a) primeiro desbaste em sistema de toras curtas (CTL) com forwarder; (b) terceiro desbaste em sistema CTL com forwarder; (c) corte raso em sistema CTL com forwarder; e (d) corte raso em sistema de árvores inteiras (FT) com skidder. A análise técnica foi realizada por meio de um estudo de tempos e movimentos, com um erro amostral menor que 10%, sendo avaliados os elementos do ciclo operacional e determinada a produtividade nominal (Pn) e efetiva (Pe). A análise de custos foi realizada através da determinação dos custos operacionais e de produção pelo método contábil. As operações foram avaliadas em diferentes condições de declividade, sentido de operação, distância de extração, presença de afloramento rochoso e classe de volume por tora, os quais também foram considerados como variáveis independes com intuito de se ajustar modelos matemáticos por regressão múltipla para a estimativa da produtividade, utilizando o procedimento Stepwise. Os principais resultados foram: para o primeiro desbaste a Pn foi de 10,90 m3/h e custo operacional total (COT) de 181,12 R$/he. Para o terceiro desbaste a Pn foi de 16,45 m3/h e COT de 185,58 R$/he. Em corte raso, para forwarder se obteve uma Pn de 29,05 m3/h e COT de 244,58 R$/he, enquanto que para o skidder se obteve uma Pn de 128,60 m3/h e COT de 218,31 R$/he. Para a modelagem da produtividade das máquinas, a distância e o volume por tora foram usadas como variáveis explicativas, estando presentes nas estimativas para o forwarder, além do volume por ciclo, em terceiro desbaste, e da declividade em primeiro desbaste e corte raso. Para o skidder, as variáveis utilizadas foram a distância e o volume por ciclo. Na etapa dois foi determinada a densidade economicamente ótima (DOE) e aceitável (DAE) para as diferentes situações de colheita. A DOE foi calculada pelo método indireto, sendo esta o produto do somatório dos custos de reconstrução, manutenção, extração e perda de área produtiva. Em primeiro desbaste a densidade de estradas atual (DE) foi de 45,28 m/ha, a DOE de 20,18 m/ha e a DAE de 28,26 m/ha. Em terceiro desbaste a DE foi de 95,08 m/ha, a DOE de 16,60 m/ha e a DAE de 21,68. Em corte raso a DE foi de 92,02 m/ha, sendo a DOE para o sistema CTL de 15,63 m/ha e DAE de 24,75 m/ha, enquanto que em sistema FT a DOE foi de 22,85 m/ha e DAE de 27,00 m/ha. De forma geral, a densidade de estradas atual foi acima da ótima e da aceitável, devendo ser realizado um replanejamento das operações visando uma malha viária dentro da densidade aceitável, resultando em menores custos e maiores receitas à empresa

Forest roads and stream crossings can be important sources of sediment in forested watersheds. The purpose of this research was to compare trapped sediment and forestry best management practice (BMP) effectiveness from haul road stream crossing approaches and ditches. The three studies in this dissertation provide a quantitative assessment of sediment production and potential sediment delivery from forest haul roads in the Virginia Piedmont and Ridge and Valley regions. Sediment production rates were measured and modeled to evaluate and compare road and ditch segments near stream crossings with various ranges of road attributes, BMPs, and management objectives. Sediment mass delivered to traps from 37 haul road stream crossing approaches ranged from <0.1 to 2.7 Mg for the one year collection. Collectively, five approaches accounted for 82% of the total sediment mass trapped. Approaches were categorized into Low, Standard, and High road quality rankings according to road attributes. Seventy-one percent (5 of 7) of Low ranked approaches delivered sediment to traps at rates greater than 11.2 Mg ha-1 yr-1. Nearly 90% of Standard or High road quality approaches generated less than 0.1 Mg of sediment over one year. Among approaches with less than 0.1 Mg of trapped sediment, road gradients ranged from 1% to 13%, bare soil ranged from 2% to 94%, and distances to nearest water control structures ranged from 8.2 to 427.0 m. Such a wide spectrum of road attributes with relatively low levels of trapped sediment indicate that contemporary BMPs can mitigate problematic road attributes and reduce erosion and sediment delivery. Three erosion models, USLE-forest, RUSLE2, and WEPP were compared to trapped sediment data from the 37 forest haul road stream crossing approaches in the first study. The second study assessed model performance from five variations of the three erosion models that have been used in previous forest operations research, USLE-roadway, USLE-soil survey, RUSLE2, WEPP-default, and WEPP-modified. The results suggest that these soil erosion models could estimate erosion and sediment delivery within 5 Mg ha-1 yr-1 for most approaches with erosion rates less than 11.2 Mg ha-1 yr-1, while model estimates varied widely for approaches that eroded above 11.2 Mg ha-1 yr-1. Based on the results from the 12 evaluations of model performance, the modified version of WEPP consistently performed better compared to all other model variations tested. However, results from the study suggest that additional field evaluations and improvement of soil erosion models are needed for stream crossings. The soil erosion models evaluated are not an adequate surrogate for informing policy decisions. The third study evaluated sediment control effectiveness of four commonly recommended ditch BMPs on forest haul road stream crossing approaches. Sixty ditch segments near stream crossings were reconstructed and four ditch BMP treatments were tested. Ditch treatments were bare (Bare), grass seed with lime fertilizer (Seed), grass seed with lime fertilizer and erosion control mat (Mat), rock check dams (Dam), and completely rocked (Rock). Mat treatments had significantly lower erosion rates than Bare and Dam, while Rock and Seed produced intermediate levels. Findings of this study suggest Mat, Seed, and Rock ditch BMPs were effective at reducing erosion, but Mat was most effective directly following construction because Mat provided immediate soil protection measures. Any BMPs that reduce bare soil can provide reduction in erosion and even natural site condition, including litterfall and invasive vegetation can provide erosion control. However, ditch BMPs cannot mitigate inadequate water control structures. Overall, forest roads and stream crossings have the potential to be major contributors of sediment in forested watersheds when roads are not designed well or when BMPs are not properly implemented. Forestry BMPs reduce stormwater runoff velocity and volume from forest roads, but can have varying levels of effectiveness due to site-specific conditions. Operational field studies provide valuable information regarding erosion and sediment delivery rates, which helps guide BMP recommendations and subsequently enhances water quality protection. / Ph. D.