A compatible growth and yield model for the management of mixed tropical rain forest

2000 ◽  
Vol 30 (2) ◽  
pp. 311-323 ◽  
Author(s):  
James Atta-Boateng ◽  
John William Moser, Jr.
Keyword(s):  
Forest Management ◽  
Rain Forest ◽  
Sustainable Use ◽  
Rate Of Change ◽  
Growth And Yield ◽  
Timber Species ◽  
Yield Model ◽  
Financial Investment ◽  
The Impact ◽  
Growth And Yield Models

The lack of appropriate analytical tools to evaluate the impact of forest management policies has hindered the sustainable use of the rain forest. Decisions about the level of forest management and financial investment require accurate predictions of future forest yields. A technique, using hierarchical clustering and canonical discriminant procedures, was developed previously to pool 112 timber species with similar growth increment characteristics into seven groups suitable for the construction of growth and yield models. Compatible growth and yield models were developed for each group by the solution of a system of differential equations expressing the rate of change of ingrowth, mortality, and survival growth components within a forest stand. The solution provides the means to project the status of the timber stand at any future time given some predefined initial stand conditions. The models are useful for inventory updating, allowable annual cut calculations, and management planning for natural or managed stands. They also provide a means to test hypotheses concerning the influence of stand characteristics on increment and to project future product assortments.

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

scholarly journals A Growth and Yield Model Incorporating Hardwood Competition for Natural Loblolly Pine Stands in the Georgia Piedmont

1999 ◽  
Vol 23 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Stacey W. Martin ◽  
Graham H. Brister
Keyword(s):  
Loblolly Pine ◽  
Basal Area ◽  
Growth And Yield ◽  
Parameter Estimates ◽  
Yield Model ◽  
Pinus Taeda L ◽  
Projection Equations ◽  
Georgia Piedmont ◽  
The Impact ◽  
Over Time

Abstract Using 5 yr remeasurement data from even-aged natural loblolly pine (Pinus taeda L.) stands in the Georgia Piedmont, a system of growth equations was developed to project pine yield over time that accounts for hardwood competition. In this system, the increase in the proportion of hardwood basal area over time is estimated, then the projected pine basal area and trees per acre are adjusted inversely to account for this increase. The parameter estimates for this system ensure compatibility between volume prediction and projection equations and the proportion of hardwood basal area, pine basal area, dominant height, and trees per acre projection equations. The whole-stand growth and yield system developed here coupled with published merchantable yield equations allow for the evaluation of the impact of hardwoods on future stand yield and product distributions. The results indicate that the impact of hardwood competition on pine yield is substantial and occurs mainly as a reduction in sawtimber volume. South. J. Appl. For. 16(3):179-185.

scholarly journals Reuse of treated wastewater in viticulture: Can it be an alternative source of nutrient-rich water?

2019 ◽  
Vol 12 ◽  
pp. 01009 ◽  
Author(s):  
F. Etchebarne ◽  
P. Aveni ◽  
J.-L. Escudier ◽  
H. Ojeda
Keyword(s):  
Good Practice ◽  
Sustainable Use ◽  
Microbiological Quality ◽  
Growth Yield ◽  
Grape Juice ◽  
Added Value ◽  
Growth And Yield ◽  
Treated Wastewater ◽  
Alternative Source ◽  
The Impact

Water scarcity is a global problem, which leads to unprecedented pressure on water supply in arid and semi-arid regions. Treating wastewater is an alternative and valuable water resource, therefore its reuse for agricultural irrigation has been growing worldwide since the beginning of the 21st century. In several regions of the wine-producing countries subject to significant water stress (e.g., Australia, California-USA, Spain), wastewater recycling appears to be the most accessible alternative, both financially and technically, for the agricultural uses that notably not requiring drinking water. Therefore, this research was planned to quantify the contribution of treated wastewater (TWW) to fertilization-needs of the vine, evaluate the impact of irrigation with TWW on the soil, vegetative growth, yield, and wine and grape juice composition. The results provide scientific and technical knowledge on a strategy of water management with high added value. The fertilizer contribution of the TWW would be important, according to the plant's nutrient needs (e.g., in this study 19–39 Unit N, 0.5–1.1 Unit P and 14–28 Unit K ha−1 were supplied with TWW). Ensuring treated wastewater microbiological quality is essential, but without reducing of its nutrients. These nutrients would be a valuable input for crop growth and yield, and could reduce the need to resort for inorganic/synthetic fertilizers. A sustainable use of treated wastewater over the long term would, however, necessitate a good practice guidelines and an integrated vision of treated wastewater quality, crops, irrigation and post-harvest practices.

scholarly journals StandsSIM-MD: a Management Driven forest SIMulator

2016 ◽  
Vol 25 (2) ◽  
pp. eRC07 ◽  
Author(s):  
Susana Barreiro ◽  
João Rua ◽  
Margarida Tomé
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Growth Models ◽  
Planning Horizon ◽  
Md Simulations ◽  
Forest Growth ◽  
Growth And Yield ◽  
Management Approaches ◽  
User Friendly ◽  
Growth And Yield Models

Aim of the study: The existing stand level forest simulators available in Portugal were not developed with the aim of including up-to-date model versions and were limited in terms of accounting for forest management. The simulators’ platform, sIMfLOR was recently created to implement different growth models with a common philosophy. The objective was developing one easily-updatable, user-friendly, forest management and climate change sensitive simulator capable of projecting growth for the main tree species in Portugal.Area of the study: Portugal.Material and methods: The new simulator was programmed in a modular form consisting of several modules. The growth module integrates different forest growth and yield models (empirical and process-based) for the main wood production tree species in Portugal (eucalypt, umbrella and maritime pines); whereas the management module drives the growth projections along the planning horizon according to a range of forest management approaches and climate (at present only available for eucalypt).Main results: The main result is the StandsSIM-MD Management Driven simulator that overcomes the limitations of the existing stand level simulators. It is a step forward when compared to the models currently available in the sIMfLOR platform covering more tree species, stand structures and stand compositions. It is focused on end-users and it is based on similar concepts regarding the generation of required inputs and generated outputs.Research highlights:-          Forest Management Driven simulations approach-          Multiple Prescriptions-Per-Stand functionality-          StandsSIM-MD can be used to support landowners decisions on stand forest management-          StandsSIM-MD simulations at regional level can be combined with optimization routinesKeywords: Forest simulator, Forest Management Approaches; StandsSIM-MD; forest management.

scholarly journals How much birch (Betula papyrifera) is too much for maximizing spruce (Picea glauca) growth: a case study in boreal spruce plantation forests

2012 ◽  
Vol 58 (No. 7) ◽  
pp. 314-327 ◽  
Author(s):  
C.D.B. Hawkins ◽  
A. Dhar ◽  
B.J. Rogers
Keyword(s):  
Picea Glauca ◽  
Management Strategies ◽  
Growth And Yield ◽  
Stem Volume ◽  
Growth Data ◽  
Mixed Species ◽  
Yield Model ◽  
Mixedwood Forests ◽  
Spruce Stands ◽  
The Impact

Interest in conifer-broadleaf mixedwood forests has greatly increased due to continuous demand for hardwood products and a shift towards more biological or ecosystem-based management. In British Columbia, more than 30% of the productive forest land is a conifer&ndash;broadleaf mixture and current forest regulations are more conifer biased rather than maintaining a mixed-species condition. The aim of this study was to examine the impact of paper birch on white spruce growth. Spruce growth data from 10 to 18 years old complex stands indicate that radial, height, and stem volume was not impacted by retaining up to 3,000 stems&middot;ha<sup>&ndash;1</sup> of birch. Similarly, growth and yield model projections suggest spruce-birch stands would be more productive up to a threshold birch density (3,000 stems&middot;ha<sup>&ndash;1</sup>) than pure spruce stands. At a 4% real interest rate, the removal of birch from these stands does not appear to be warranted as an investment. The results suggest that instead of encouraging uniform broadleaf removal across conifer plantations, mixed species management strategies could enhance the forest productivity, stand diversity and resilience. &nbsp;

scholarly journals A preliminary growth and yield model for Eucalyptus globoidea Blakely plantations in New Zealand

2020 ◽  
Vol 50 ◽  
Author(s):  
Serajis Salekin ◽  
Euan G. Mason ◽  
Justin Morgenroth ◽  
Dean F. Meason
Keyword(s):  
New Zealand ◽  
Basal Area ◽  
Growth And Yield ◽  
Maximum Diameter ◽  
Forest Industry ◽  
Eucalyptus Species ◽  
Plantation Forest ◽  
Yield Model ◽  
Growth And Yield Model ◽  
Growth And Yield Models

Background: New Zealand’s plantation forest industry is dominated by the exotic species radiata pine (Pinus radiata D.Don), which comprises approximately 90% of the net stocked area. However, there is interest in introducing new species to: (a) provide wood that is naturally decay-resistant as a substitute for wood treated with preservatives; (b) match species to the wide variety of environmental conditions in New Zealand; and (c) reduce reliance on P. radiata. Some Eucalyptus species are considered as potential alternatives to P. radiata, specifically those that can survive in resource-limited conditions and produce high quality wood. While Eucalyptus species are grown in plantations in many regions of the world, limited information is available on their growth in New Zealand. Eucalyptus globoidea Blakley is of particular interest and has been planted in trials throughout New Zealand. A complete set of preliminary growth and yield models for this species will satisfy the initial information requirements for diversifying New Zealand’s plantation forest industry. Methods: A set of growth and yield models was developed and validated, based on data from 29 E. globoidea permanent sample plots (PSPs) located mostly in North Island and a few in South Island of New Zealand. Trees were measured at different time intervals in these plots, with height and diameter at breast height (DBH) ranging from 0.1–39.8 m and 0.1–62.3 cm, respectively. An algebraic difference approach (ADA) was applied to model mean top height, basal area, maximum diameter, and standard deviation of DBH. Non-linear regression equations were used to project stand volume and height-diameter relationship, and Reineke’s stand density index (SDI) approach was employed to model mortality. Results: Mean top height, maximum diameter, and standard deviation of DBH were best fitted by Von Bertalanffy-Richards (SE=1.1 m), Hossfeld (SE=2.4 cm), and Schumacher polymorphic (SE=1.6 cm) difference equations, respectively. Basal area data were modelled with high precision (SE=6.9 m2 ha-1) by the Schumacher anamorphic difference equation. Reineke’s SDI approach was able to explain the self-thinning as a reduction in the number of stems per hectare. Stand-level volume per hectare and height-diameter relationship models were precise when including site-specific variables with standard errors of 40.5 m3 ha-1 and 3.1 m, respectively. Conclusion: This study presents a set of preliminary growth and yield models for E. globoidea to project plot-level growth attributes. The models were path invariant and satisfied basic traditional mensurational-statistical growth and yield model assumptions. These models will provide forest growers and managers with important fundamental information about the growth and yield of E. globoidea.

scholarly journals Impacts of Participatory Forest Management on Community Livelihood: Case study of Kereita forest Kenya

2021 ◽  
Author(s):  
◽  
Leah Gichuki
Keyword(s):  
Forest Management ◽  
Political Ecology ◽  
Forest Conservation ◽  
Sustainable Use ◽  
Forest Products ◽  
Structured Interviews ◽  
Participatory Forest Management ◽  
The Government ◽  
The Impact

<p>Since the 1990s there has been an increasing shift in the management of natural resources from state control to participatory approaches. Many developing countries, including Kenya, have promoted participatory forest management (PFM) as a strategy for enhancing forest conservation and the sustainable use of forest resources through community participation. Drawing on a case study of the Kereita forest, in the central highlands of Kenya, this research explores the impact of PFM on community livelihood. Using a post-structural political ecology approach and qualitative research methods, I conducted and analysed 18 semi-structured interviews.  Results indicate that the implementation of PFM has changed how the community access forest products. PFM, through processes of inclusion and exclusion, has had both positive and negative effects on community livelihoods. New opportunities were opened, for instance, increased awareness about forest conservation led to a women’s group developing alternative livelihood pathways. In contrast, the development of a new eco-lodge disrupted community plans to rehabilitate that area.   This case study also reflected other critiques of PFM in terms of who holds ultimate authority; ultimately, the government retained a lot of control in forest management, and PFM processes have concentrated power with the government and channelled certain livelihood outcomes that benefit the already wealthy. These uneven power relations between the community and the government produce and perpetuate conflicts in implementing PFM hence hampering livelihood improvement. Furthermore, I argue that PFM has created and embedded both visible and invisible boundaries – through fences and permits, for instance – that regulate what takes place where, and who accesses what. To sustain the development of good community livelihoods through PFM, this research calls for continued interrogations of power imbalances within current PFM structures.</p>

Improving growth and yield estimates with a process model derived growth index

2004 ◽  
Vol 34 (6) ◽  
pp. 1274-1282 ◽  
Author(s):  
Jason G Henning ◽  
Thomas E Burk
Keyword(s):  
Process Model ◽  
Environmental Variability ◽  
Growth Index ◽  
Process Models ◽  
Growth And Yield ◽  
Yield Model ◽  
Forest Inventories ◽  
Model Predictions ◽  
Growth And Yield Models ◽  
Empirical Growth

Forest managers have long made use of the regular and predictable nature of tree growth by using empirical growth and yield models to update forest inventories. Updated inventories support better decision making without requiring on the ground reassessment of the forest resource. Growth and yield model predictions can suffer from inaccuracies due to the influence of climate and environmental variability on the growth of trees. Researchers have been attempting to assess and predict the effect of this variation by developing mechanistic process models that often do not generate outputs applicable to inventory update. Here we create a growth index dependent on process model outputs to improve growth and yield estimates. Estimate accuracy was modestly improved over the basic growth and yield estimates and was comparable to previous efforts to account for environmental variability in growth and yield estimates. Using a process model we are nominally considering the entire environment, and by adjusting the growth and yield estimates external to both model types we have avoided difficulties involved with refitting or recreating either model. These are key differences from previous efforts to include environmental variability in growth and yield estimates.

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