scholarly journals Evaluating the long-term influence of alternative commercial thinning regimes and harvesting systems on projected net present value of precommercially thinned spruce–fir stands in northern Maine

2017 ◽  
Vol 47 (2) ◽  
pp. 203-214 ◽  
Author(s):  
Patrick Hiesl ◽  
Mindy S. Crandall ◽  
Aaron Weiskittel ◽  
Jeffrey G. Benjamin ◽  
Robert G. Wagner
Keyword(s):  
Net Present Value ◽  
Growth And Yield ◽  
Stand Age ◽  
Present Value ◽  
Yield Model ◽  
Individual Tree ◽  
Commercial Thinning ◽  
Harvesting Systems ◽  
Timing Of Entry

Commercial thinning (CT) is an important silvicultural practice in the northeastern United States. Relatively little is known, however, about the interaction of harvest system and treatment (removal intensity or timing of entry) on the overall profitability of CT. To address this question, 10-year measurements from a controlled CT experiment across six sites in Maine were used to project the long-term effect of removal intensity (33% and 50% relative density reduction) and timing of entry (no delay, 5-year delay, 10-year delay) on (i) maximum net present value (NPV), (ii) timing of maximum NPV, and (iii) the effect of three harvesting systems (cut-to-length, whole-tree, hybrid systems) on maximum NPV. A regional growth and yield model was used to project individual-tree growth and mortality into the future. Harvest costs for the harvesting systems were estimated using regional cycle-time equations. No difference was found in maximum NPV between the CT and non-CT areas or the timing of CT entry. Stand age at time of maximum NPV differed between delays but not between the two removal intensities. Our results indicate that there is no economic benefit in delaying a CT or removing more volume at the time of thinning for the range of stand conditions evaluated.

scholarly journals Comprehensive yield model for plantation teak in Panama

Silva Fennica ◽  
2020 ◽  
Vol 54 (5) ◽  
Author(s):  
Petteri Seppänen ◽  
Antti Mäkinen
Keyword(s):  
Input Parameter ◽  
Large Diameter ◽  
Measurement Data ◽  
Growth And Yield ◽  
Tree Level ◽  
Stem Volume ◽  
Yield Model ◽  
Individual Tree ◽  
Support Tool ◽  
Volume Models

The purpose of this study was to prepare a comprehensive, computerized teak ( L.f) plantation yield model system that can be used to describe the forest dynamics, predict growth and yield and support forest planning and decision-making. Extensive individual tree and permanent sample plot data were used to develop tree-level volume models, taper curve models and stand-level yield models for teak plantations in Panama. Tree volume models were satisfactorily validated against independent measurement data and other published models. Tree height as input parameter improved the stem volume model marginally. Stand level yield models produced comparable harvest volumes with models published in the literature. Stand level volume product outputs were found like actual harvests with an exception that the models marginally underestimate the share of logs in very large diameter classes. The kind of comprehensive model developed in this study and implemented in an easy to use software package provides a very powerful decision support tool. Optimal forest management regimes can be found by simulating different planting densities, thinning regimes and final harvest ages. Forest practitioners can apply growth and yield models in the appropriate stand level inventory data and perform long term harvest scheduling at property level or even at an entire timberland portfolio level. Harvest schedules can be optimized using the applicable financial parameters (silviculture costs, harvesting costs, wood prices and discount rates) and constraints (market size and operational capacity).Tectona grandis

Creating continuous areas of old forest in long-term forest planning

2000 ◽  
Vol 30 (11) ◽  
pp. 1817-1823 ◽  
Author(s):  
Karin Öhman
Keyword(s):  
Net Present Value ◽  
Problem Formulation ◽  
Core Area ◽  
Northern Sweden ◽  
Present Value ◽  
The Core ◽  
Long Range Planning ◽  
The Cost

Harvest activities tend often to create landscapes where the old forest is fragmented into isolated patches that provide marginal conditions for species that inhabit forest interiors. This paper presents a long-range planning model designed to maximize the net present value and to create continuous patches of old forest. In this model, the spatial structure of old forest is controlled by core area and edge habitats. Core area is defined as the area of old forest that is free of edge effects from surrounding habitats. The core area requirement is set to a fixed value for each of a number of time periods, whereas the area of edge habitats, which should be as small as possible, is weighted against the net present value. The model is applied in a case study to an actual landscape consisting of 755 stands of forest in northern Sweden and solved using simulated annealing. The results show that distinct continuous patches of old forest are created when both a core area requirement and consideration of the amount of edge habitats are included in the problem formulation. The cost of creating continuous areas of old forest was found to be significant.

Evaluating the influence of stem form and damage on individual-tree diameter increment and survival in the Acadian Region: implications for predicting future value of northern commercial hardwood stands

2018 ◽  
Vol 48 (9) ◽  
pp. 1007-1019 ◽  
Author(s):  
Mark Castle ◽  
Aaron Weiskittel ◽  
Robert Wagner ◽  
Mark Ducey ◽  
Jereme Frank ◽  
...  
Keyword(s):  
Growth And Yield ◽  
Tree Level ◽  
Permanent Plots ◽  
Stem Form ◽  
Individual Tree ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Hardwood Species ◽  
Future Value

Northern hardwood species display a variety of forms and defects that can reduce stem quality and complicate their timber management. However, for the most part, growth and yield models do not account for the influence of stem form and damage. This study determined the influence of stem form and damage on growth, survival, and projected future sawlog value among several northern commercial hardwood species. To accomplish this, hardwood trees on 112 permanent plots across three long-term research sites in Maine were assigned stem form and risk classes using a tree classification system developed in New Brunswick. A highly significant influence of stem form and risk on annualized individual-tree diameter increment and survival was found. Inclusion of these equations into a regional growth and yield model highlighted the importance of stem form and defects on long-term simulations as projected stand-level future value was significantly reduced by over 17%, on average (range of 13% to 28%), when compared with projections that did not include that tree-level information. The results highlight the importance of stem form and defects, as well as the need to account for them, in growth and yield applications that assess the forecasted value of commercially important hardwood stands.

scholarly journals Stand-Level Components of a Growth and Yield Model for Nothofagus Mixed Forests from Southern Chile

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 810
Author(s):  
Sebastian Palmas ◽  
Paulo C. Moreno ◽  
Wendel P. Cropper ◽  
Alicia Ortega ◽  
Salvador A. Gezan
Keyword(s):  
Forest Type ◽  
Geographical Area ◽  
Basal Area ◽  
Forest Growth ◽  
Model Systems ◽  
Growth And Yield ◽  
Permanent Plots ◽  
Stand Age ◽  
Yield Model ◽  
Mixed Forests

Reliable information on stand dynamics and development is needed to improve management decisions on mixed forests, and essential tools for this purpose are forest growth and yield (G&Y) models. In this study, stand-level G&Y models were built for cohorts within the natural mixed second-growth Nothofagus-dominated forests in Chile. All currently available (but limited) data, consisting of a series of stratified temporary and permanent plots established in the complete range of this forest type, were used to fit and validate these models. Linear and nonlinear models were considered, where dominant stand age, number of trees, and the proportion of basal area of Nothofagus species resulted in significant predictors to project future values of stand basal area for the different cohorts (with R2 > 0.51 for the validation datasets). Mortality was successfully modeled (R2 = 0.79), based on a small set of permanent plots, using the concept of self-thinning with a proposed model defined by the idea that, as stands get closer to a maximum density, they experience higher levels of mortality. The evaluation of these models indicated that they adequately represent the current understanding of dynamics of basal area and mortality of Nothofagus and companion species in these forests. These are the first models fitted over a large geographical area that consider the dynamics of these mixed forests. It is suggested that the proposed models should constitute the main components of future implementations of G&Y model systems.

scholarly journals An Analysis of the Effectiveness of Two Rainwater Harvesting Systems Located in Central Eastern Europe

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 458 ◽  
Author(s):  
Agnieszka Stec ◽  
Martina Zeleňáková
Keyword(s):  
Sensitivity Analysis ◽  
Net Present Value ◽  
Rainwater Harvesting ◽  
Payback Period ◽  
Practical Aspect ◽  
Financial Ratios ◽  
Present Value ◽  
Toilet Flushing ◽  
Harvesting Systems ◽  
The Impact

Decentralized water systems are perceived as solutions that not only save water, but also as a way to partially or completely become independent from centralized suppliers. Taking this into account, an analysis of the effectiveness of rainwater harvesting systems (RWHS) for toilet flushing in existing academic facilities located in Poland and in Slovakia was carried out. The tests took into account the different volumes of storage tanks collecting rainwater. On the basis of two financial ratios, namely Net Present Value and Discounted Payback Period, the profitability of these systems was also assessed. The research was extended by the sensitivity analysis, which allowed determination of the impact of changes in individual cost components on the financial effectiveness of the investments considered. The results obtained clearly showed that the implementation of RWHS in the dormitory in Rzeszów was unprofitable for all tank capacities tested, and the payback period significantly exceeded the period of 30 years accepted for the analysis. Completely different results were obtained for RWHS in a dormitory located in the city of Košice, for which the financial ratios NPV (Net Present Value) and DPP (Discounted Payback Period) were very favorable. It was also confirmed by the results of the sensitivity analysis. The use of rainwater for toilet flushing caused that it was possible to achieve water savings of an average of 29% and 18%, respectively, for facilities located in Slovakia and Poland. The results of the research have a practical aspect and can provide an indication for potential investors and managers of academic facilities, similar to those analyzed in the article. Taking into account that in many countries water and sewage rates are significantly higher than in Poland and Slovakia, the cost-effectiveness of using the analyzed installation options in these countries could be even higher.

A simple growth and yield model for assessing changes in standing volume across Canada’s forests

2009 ◽  
Vol 85 (1) ◽  
pp. 57-64 ◽  
Author(s):  
C -H. Ung ◽  
P Y Bernier ◽  
X J Guo ◽  
M -C. Lambert
Keyword(s):  
Predictive Power ◽  
Robust Regression ◽  
Forest Growth ◽  
Growth Potential ◽  
Growth And Yield ◽  
Stand Age ◽  
Yield Model ◽  
Wood Volume ◽  
National Model ◽  
Growth And Yield Models

We have adjusted two growth and yield models to temporary sample plots from across Canada, and used climate variables in lieu of phytometric indices such as site index to represent, in part, the site-level variability in growth potential. Comparison of predicted increments in plot-level height, basal area and merchantable wood volume to increments of these variables measured in permanent sample plots shows a moderate to poor predictive ability. Comparison with the performance of four operational growth and yield models from different provinces across Canada shows comparable predictive power of this new model versus that of the provincial models. Based on these results, we suggest that the simplification of regional growth and yield models may be achieved without further loss of predictive power, and that the large error in the prediction of growth increment is mostly associated with the use of temporary sample plots which, by definition, contain little information on stand dynamics. We also suggest that, because of the empirical nature of these growth and yield models, the scale of application should determine the appropriate scale of the model. National estimates of forest growth are therefore less likely to be biased if obtained from a national model only than if obtained from a combination of regional models, where those exist, gap-filled with estimates from a national model. Key words: yield model, merchantable wood volume, stand age, climatic variables, simultaneous regression, robust regression

Predicted Genetic Gains from one Generation of Slash Pine Tree Improvement

1989 ◽  
Vol 13 (1) ◽  
pp. 51-56 ◽  
Author(s):  
G. R. Hodge ◽  
T. L. White ◽  
G. L. Powell ◽  
S. M. De Souza
Keyword(s):  
First Generation ◽  
Pinus Elliottii ◽  
Tree Improvement ◽  
Slash Pine ◽  
Growth And Yield ◽  
Yield Model ◽  
Individual Tree ◽  
Fusiform Rust ◽  
Pine Tree ◽  
Growth And Yield Model

Abstract Gains over unimproved seed for progeny from first generation--un-rogued, first generation--rogued, and one and one-half generation orchards of slash pine (Pinus elliottii var. elliottii) for individual tree volume at 15 years are predicted to be 10%, 15%, and 19%, respectively. Rustinfection of orchard progeny on sites where unimproved material incurs 50% infection are predicted to be 49%, 41%, and 35% for the three orchard types. Using a growth and yield model that incorporates fusiform rust, gains in individual tree volume and increased rust resistance were combinedto estimate effects on per acre yields. Percent volume per acre gains are predicted to be 7.0%, 13.2%, and 18.0% for the three orchard types. Collection and deployment of the most rust resistant seed to high rust hazard sites raises the gain on these sites and becomes increasingly beneficialas the rust hazard increases. South. J. Appl. For. 13(1): 51-56.

SYLVER: Modelling the Impact of Silviculture on Yield, Lumber Value, and Economic Return

1988 ◽  
Vol 64 (2) ◽  
pp. 127-131 ◽  
Author(s):  
Kenneth J. Mitchell
Keyword(s):  
Net Present Value ◽  
Financial Analysis ◽  
Wood Properties ◽  
Growth And Yield ◽  
Present Value ◽  
Silvicultural Treatments ◽  
Intensive Forest Management ◽  
Product Value ◽  
Analysis System ◽  
The Impact

Intensive forest management requires an understanding of the effect that silvicultural treatments have on wood properties, standing yield, log quality, product value, and net present value. These needs are addressed by a system of models (SYLVER) which includes the Tree and Stand Simulator (TASS), Root Rot Simulator (ROTSIM), Sawmill Simulator (SAWSIM), and the new Financial Analysis System (FAN$Y). The latter will be used by field foresters to compare the merits of candidate treatments for specific stands. Key words: Silviculture, growth and yield, juvenile wood, log quality, end-product value, net present value, Pseudotsuga menziesii, Phellinus weirii, modelling, TASS, ROTSIM, SAWSIM, FAN$Y, SYLVER.

scholarly journals An evaluation of the economic viability of environmental offsets in the saltworks industry

2020 ◽  
Vol 50 (5) ◽  
Author(s):  
Rogério Taygra Vasconcelos Fernandes ◽  
Aruza Rayana Morais Pinto ◽  
Raimunda Thyciana Vasconcelos Fernandes ◽  
Jônnata Fernandes de Oliveira ◽  
José Luís Costa Novaes
Keyword(s):  
Economic Impact ◽  
Net Present Value ◽  
Economic Viability ◽  
Attractive Alternative ◽  
Present Value ◽  
Conservation Units ◽  
Productive Area ◽  
Solar Saltworks ◽  
Do So

ABSTRACT: The extraction of sea salt depends on the occupation of large areas at the estuary banks, many of them inserted in Permanent Preservation Areas (PPAs). Thus, the objective was to evaluate the economic viability of Environmental Offsets (EO) as an alternative to the unoccupied PPAs in the saltworks. In order to do so, 27 solar saltworks installed in the region of the Brazilian White Coast were evaluated for the occupation of PPAs - measured using images from satellite, georeferenced, vectored with corresponding PPA bands generated - and estimated to EO (Impact Degree x Sum of the investments necessary to implement the project) and Economic Impact (Net Present Value, with long-term interest rate of 7%) of vacating PPAs. It was considered that EO was feasible whenever the costs resulting from it were lower than the economic impact caused by the vacancy of the PPAs. The PPAs were tthe productive area of the saltworksthat occupied 13.70% of PPAs. For all the evaluated enterprises the value corresponding to EO was lower than the Economic Impact resulting from the vacancy of the PPAs. Thus, EO is an economically viable and more attractive alternative to the eviction of PPAs by the saltworks industry and may also provide environmental gains due to the financing of conservation units in the areas of influence of the enterprises. However, there is a need to improve the methodology used to estimate the EO, since a maximum limit is set, the environmental impacts caused by the projects are underestimated.

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