The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30...The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand,comprising 24 sample plots used for model fitting,and six sample plots for validation.The volume of wood per hectare was estimated for different productive units(sites),using 7 years as the reference age.The model adjustment quality was verified by adjustment and precision statistics:the correlation between observed and predicted variables,root mean square error percentage,graphical analysis of residual distribution,and a frequency histogram for classes of relative errors and validation.Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age(7 years)in the different productivity classes,it generated imprecise estimates of the number of individuals.Consequently,it produced inaccurate volumetric production estimates.The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types,showing compatibility with the pre-cut inventory according to a Tukey test.In summary,the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.展开更多
Integration system is used to denote practices that combine systematic use of the land and technologies,in which forest species are used in conjunction with herbaceous plants and/or animals respecting a spatial or tem...Integration system is used to denote practices that combine systematic use of the land and technologies,in which forest species are used in conjunction with herbaceous plants and/or animals respecting a spatial or temporal arrangement.Knowing that this type of production seeks to balance ecological and economic factors,it is important to understand the financial benefits and risks involved in this production.Financial analysis,therefore,acts as an important analysis tool to foster this type of activity.The paper aimed to conduct analysis of investment risk of a crop-livestock-forestry system deployed in Brazil,comparing two different production scenarios,scenario I with 17 ha and scenario II with 25 ha.The risk analysis was performed using the Monte Carlo method and sensitivity analysis(by varying the factors:the discount rate,productivity and price).A cash flow was elaborated based on annual cost and revenues data of the agricultural crops(corn and soybeans),livestock and eucalyptus,using an interest rate of 6%per year.The results indicated that the optimal age for cutting the eucalyptus was at seven years on both scenarios;scenario I had better return on investment using deterministic and probabilistic methods;scenario I presents higher investments risks;there is a negative relation between discount rate and annualized net present value(ANPV);increased productivity of crops provides greater profitability to the system;there has been an increase in the economic viability of the system,as value has been added to the products.Monte Carlo method and the sensitivity analysis showed to be an appropriate tool to analyze the risk of crop-livestock-forestry systems,making it possible to foresee how the project will respond to possible scenarios.展开更多
基金supported by the University of Brasilia and the National Council for Scientific and Technological Development(CNPq)。
文摘The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand,comprising 24 sample plots used for model fitting,and six sample plots for validation.The volume of wood per hectare was estimated for different productive units(sites),using 7 years as the reference age.The model adjustment quality was verified by adjustment and precision statistics:the correlation between observed and predicted variables,root mean square error percentage,graphical analysis of residual distribution,and a frequency histogram for classes of relative errors and validation.Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age(7 years)in the different productivity classes,it generated imprecise estimates of the number of individuals.Consequently,it produced inaccurate volumetric production estimates.The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types,showing compatibility with the pre-cut inventory according to a Tukey test.In summary,the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.
文摘Integration system is used to denote practices that combine systematic use of the land and technologies,in which forest species are used in conjunction with herbaceous plants and/or animals respecting a spatial or temporal arrangement.Knowing that this type of production seeks to balance ecological and economic factors,it is important to understand the financial benefits and risks involved in this production.Financial analysis,therefore,acts as an important analysis tool to foster this type of activity.The paper aimed to conduct analysis of investment risk of a crop-livestock-forestry system deployed in Brazil,comparing two different production scenarios,scenario I with 17 ha and scenario II with 25 ha.The risk analysis was performed using the Monte Carlo method and sensitivity analysis(by varying the factors:the discount rate,productivity and price).A cash flow was elaborated based on annual cost and revenues data of the agricultural crops(corn and soybeans),livestock and eucalyptus,using an interest rate of 6%per year.The results indicated that the optimal age for cutting the eucalyptus was at seven years on both scenarios;scenario I had better return on investment using deterministic and probabilistic methods;scenario I presents higher investments risks;there is a negative relation between discount rate and annualized net present value(ANPV);increased productivity of crops provides greater profitability to the system;there has been an increase in the economic viability of the system,as value has been added to the products.Monte Carlo method and the sensitivity analysis showed to be an appropriate tool to analyze the risk of crop-livestock-forestry systems,making it possible to foresee how the project will respond to possible scenarios.
