Scaling issues in forest ecosystem management and how to address them with models

Scaling is widely recognized as a central issue in ecology. The associated cross-scale interactions and process transmutations make scaling (i.e. a change in spatial or temporal grain and extent) an important issue in understanding ecosystem structure and functioning. Moreover, current concepts of ecosystem stewardship, such as sustainability and resilience, are inherently scale-dependent. The importance of scale and scaling in the context of forest management is likely to further increase in the future because of the growing relevance of ecosystem services beyond timber production. As a result, a consideration of processes both below (e.g. leaf-level carbon uptake in the context of climate change mitigation) and above (e.g. managing for biodiversity conservation at the landscape scale) the traditional focus on the stand level is required in forest ecosystem management. Furthermore, climate change will affect a variety of ecosystem processes across scales, ranging from photosynthesis (tree organs) to disturbance regimes (landscape scale). Assessing potential climate change impacts on ecosystem services thus requires a multi-scale perspective. However, scaling issues have received comparatively little attention in the forest management community to date. Our objectives here are thus first, to synthesize scaling issues relevant to forest management and second, to elucidate ways of dealing with complex scaling problems by highlighting examples of how they can be addressed with ecosystem models. We have focused on three current management issues of particular importance in European forestry: (1) climate change mitigation through carbon sequestration, (2) multi-functional stand management for biodiversity and non-timber goods and services and (3) improving the resilience to natural disturbances. We conclude that taking into account the full spatiotemporal heterogeneity and dynamics of forest ecosystems in management decision-making is likely to make management more robust to increasing environmental and societal pressures. Models can aid this process through explicitly accounting for system dynamics and changing conditions, operationally addressing the complexity of cross-scale interactions and emerging properties. Our synthesis indicates that increased attention to scaling issues can help forest managers to integrate traditional management objectives with emerging concerns for ecosystem services and therefore deserves more attention in forestry.     

Design and development of agroforestry systems for Illinois,USA: silvicultural and economic considerations

Recommended managerial inputs and associated outputs expected from practicing agroforestry on marginal farm lands in the central USA are discussed. Modeled management combinations are based on five timber species, three sites indices, three timber growth rates, five agricultural crops, all common crop rotations, and three tillage systems. Black walnut (Juglans nigra L.), combined with row crop production, is used to illustrate a specific multicropping alternative. Based on net present value, modeled agroforestry systems incorporating black walnut performed better on the better sites and at the medium to high timber growth rates whereas management systems using red oak (Quercus rubra L.) with row crops performed better on the poorer sites and at the lower growth rates. For agroforestry to be competitive with traditional agriculture, medium to high timber growth rates were necessary. Also, lower interest rates and the existing U.S. income tax structure favored agroforestry versus traditional agriculture. Substantial increases in net income may be possible through incorporating other income producing activities such as nut production within the agroforestry system.     

A financial evaluation of two contrasting silvicultural systems applicable to Pinus taeda grown in north-east Uruguay

The Loblolly pine (Pinus taeda L.) plantation area in north-east Uruguay was 108 000 ha in 2008. Recent industrial capacity developments have resulted in major structural changes. Silvicultural system selection depends on site productivity, costs, timber prices and public policies. This study aimed to assess economic returns for two silvicultural systems in north-east Uruguay, in scenarios with and without a plantation subsidy: System I, with a short, 12-year rotation, primarily for small logs; and System II, with a longer, 24-year rotation. For System I, the underbark volume was 198 m³ ha^?1 (mean annual increment16.5 m³ ha^?1 y?¹) and land expectation value (LEV) at a 9.7% discount rate was US$561 ha^?1 and US$442 ha^?1, with and without subsidy, respectively. System II resulted in 318 m³ ha^?1 underbark volume (13.2 m³ ha^?1 y^?1) and the LEV was US$860 ha^?1 and US$771 ha^?1, with and without subsidy, respectively. System I was more profitable than extensive cattle husbandry only when the distance to mill was equal to or less than 60 km and wood millyard prices were equal to or higher than US$27.8 m^?3 and US$28.8 m^?3 with and without subsidy, respectively. Values for System II, in which the main product was a mix of sawlog diameters, were positive and higher than those for System I, both with and without subsidy. If a company invested in forest plantations without due provision for early silvicultural treatments, such as pruning and precommercial thinning, a high risk of financial loss would ensue. Long-rotation sawtimber regimes similar to System II would be more profitable and offer a lower risk of financial losses. The results suggest subsidy withdrawal in Uruguay should not lead to changes in silvicultural systems; in fact, it rendered regimes designed for low-value wood, such as System I, even less advisable.     

A silvicultural management tool for the Oriental beech (Fagus orientalis Lipsky) forests

Stand density management tools help forest managers and landowners to more effectively allocate growing space so that specific silvicultural objectives can be met. Due to the economic importance of Oriental beech (Fagus orientalis Lipsky) forests in Turkey, a stand density management tool was developed for this species to optimize regeneration success rate and tree growth. For the development of this tool, named stand density management diagram (SDMD), we utilized forest inventory data from the Kastamonu Regional Forest Directorate in Turkey. Previously published forest management approaches and models were employed during the development of the tool. The SDMD illustrates the relation among four forest indexes: the basal area per hectare, number of trees per hectare, forest stand volume per hectare, and quadratic mean diameter of the beech stands. The stand stocking percent (SSP) can be determined based upon any two of these four measurements. The results suggest that SSP is a better predictor of tree growth than BA in Oriental beech forests. The newly developed SDMD allows for a more effective use of the growing space to achieve specific silvicultural objectives including tree regeneration, timber production, thinning planning, and wildlife protection in Oriental beech forests.     

Water yield changes as a result of silvicultural treatments in an oak ecosystem

Interception loss represents an important factor of water balance. The reduction of interception loss through silvicultural treatments to the benefit of water yield is very important for countries with large periods of limited rainfall like Greece. In the context of climate change and its possible effects on water availability, oak ecosystems can play a significant role in water production, as they comprise the largest part of the forested area in Greece. The objective of this study is to investigate the relationships between water interception changes, as a result of different forest management treatments, and water yield. For this reason, experimental watersheds have been established for the study of the hydrological impacts of thinning and clearcutting in an oak ecosystem in northern Greece. Two watersheds were used as control while different combinations of thinning (removal 50% of basal area) and clearcutting treatments were used in the other three study watersheds. Canopy annual interception amounted for 9.0%, 6.7% and 1.8% of the total precipitation in the untreated, thinned and clearcut plots respectively. The practiced thinning and clearcutting operations increased the available amount of water by a mean annual average of 13.2 mm and 42.8 mm respectively compared to the control watersheds. The total water surplus represented 29.5%, 30.9% and 33.9% of the average annual precipitation for the control, thinned and clearcut plot respectively. Surface flow was very low even during large rainfall events, possibly due to the soil and bedrock attributes and the topography of the area. Analogous silvicultural treatments can increase water availability but they should incorporate reduced-impact logging and skidding practices and thus cause the least possible soil disturbance, by carefully selecting the best suited wood harvesting systems and methods.     

A silvicultural strategy for managing uneven-aged beech-dominated forests in Thuringia,Germany: a new approach to an old problem

Maintaining a permanent forest canopy cover and eventually harvesting wood in a final harvest according to predefined dimensions is often considered as prototype for future management of deciduous forests. An uneven-aged structure is considered by the public to resemble “natural” conditions, and by forest engineers it is considered as being more resilient to disturbances. In the Hainich-Dün region of Thuringia, Germany, beech-dominated selection forests covering about 10,000?ha have been managed for almost 1000 years, initially by irregular use, but as regular selection system since about 200 years. Managing these stands remains difficult, due to the lack of yield tables and a quantification of harvest of uneven-aged stands considering differences in site conditions and handling of over-sized trees. It is the objective of the present study to develop tables of target stand volumes, increments, and harvest for different diameter ranges of uneven-aged stands according to site conditions. The present study is based on repeated grid-based inventories of about 2150 plots, which were partly re-inventoried 3 times over the past 20 years. The recommended target wood volumes vary between 296 and 388 m³ ha^?1. Stand growth rates of different yield classes were estimated to range between 6.7 and 7.7 m³ ha^?1 yr^?1 which is 30% lower than for age class forest. Nevertheless, the economic returns are higher. Thus, selective cutting with single tree selection remains a viable silvicultural system, but it may change over time into small-scale shelter-woods for improving growth of regeneration.     

A critical view on benefit-cost analyses of silvicultural management options with declining discount rates

The long planning perspective is one of the unique features of forestry. How to value money flows expected in the far distant future is therefore a crucial question. Applying time declining discount rates (DDR) may offer an appropriate alternative to conventional discounting, but few studies have applied DDRs in forest economics. We expect that theoretical assumptions behind welfare analyses based on DDR will be important. Using a dataset from the UK (Davies and Kerr (2015) [Forests 6: 2424–2449]) we investigate the effects of 1) more than marginal contributions from forestry to consumption, 2) the role of the assumed scenarios for return on capital, and 3) ignoring optimization (i.e. adopting predefined management scenarios) on the ranking of different silvicultural strategies. These include various clearfelling options (with replanting, natural regeneration or underplanting) and the transition to continuous cover forestry. Our analysis reveals that changes in these aspects affect the ranking of forest management options more strongly than a pure change in the coefficients of a benefit cost analysis. Decreasing marginality, cautious assumptions about the worst-case return on capital and optimization of silvicultural operations all increase the relative attractiveness of continuous cover forestry. We conclude that applying DDR makes valuation in forestry more demanding and should be applied with appropriate care. In addition, the precise assumptions behind the particular schedule of DDRs should be explicit. Finally, theoretical considerations support the importance of combining optimization of silvicultural management strategies with their economic evaluation.     

The stability of different silvicultural systems: a wind-tunnel investigation

We report on a wind-tunnel study with 1 : 75 scale model treesdesigned to examine the influence of canopy structure on theformation of turbulent gusts above forests. This was to testthe hypothesis that more irregular canopy structures produceless intense gusts because the change in wind speed with heightat canopy top is less severe. Measurements were made of windspeeds and turbulence within and above the model forests andof the wind loading on model trees in four different silviculturalsystems. The systems tested were even-aged, single-tree selection,shelterwood/group selection and strip felling. The measurementsshowed that the profiles of different mean wind and turbulencecharacteristics above the forests are remarkably similar whenvertical heights are normalized by the height of the tallesttree but differences do exist within the canopy. The wind loadingmeasurements indicated no difference between the systems interms of stability except possibly for the shelterwood/groupselection. In the shelterwood/group selection system the presenceof smaller sub-canopy trees appears to reduce the loading onthe main canopy trees either by providing support and increasingdamping or by absorption of energy from the canopy-penetratinggusts.     

银中杨栽培及经营管理技术研究

银中杨系人工杂交新品种，研究认为，营造银中杨应选择充分熟化的土地，采用全面整地方式；应用２ａ生根桩及二根一干、二根二干苗造林；造林密度根据材种不同可采用２ｍ×４ｍ、３ｍ×４ｍ及４ｍ×４ｍ株行距；银中杨与胡枝子、云杉混交具有促进生长作用；造林后要及时进行修枝和必要的施肥管理。     

GIS Coop: networks of silvicultural trials for supporting forest management under changing environment

Key message

The diversity of forest management systems and the contrasted competition level treatments applied make the experimental networks of the GIS Coop, a nationwide testing program in the field of emerging forestry topics within the framework of the ongoing global changes.

Context

To understand the dynamics of forest management systems and build adapted growth models for new forestry practices, long-term experiment networks remain more crucial than ever.

Aims

Two principles are at the basis of the experimental design of the networks of the Scientific Interest Group Cooperative for data on forest tree and stand growth (GIS Coop): contrasted and extreme silvicultural treatments in diverse pedoclimatic contexts.

Methods

Various forest management systems are under study: regular and even-aged stands of Douglas fir, sessile and pedunculate oaks, Maritime and Laricio pines, mixed stands of sessile oak, European silver fir, and Douglas fir combined with other species. Highly contrasted stand density regimes, from open growth to self-thinning, are formalized quantitatively.

Results

One hundred and eighty-five sites representing a total of 1206 plots have been set up in the last 20 years, where trees are measured regularly (every 3 to 10 years). The major outputs of these networks for research and management are the calibration/validation of growth and yield models and the drawing up of forest management guides.

Conclusion

The GIS Coop adapts its networks so that they can contribute to develop growth models that explicitly integrate pedoclimatic factors and thus also contribute to research on the sustainability of ecosystems under environmental and socio-economic changes.

     

Assemblages of wood-inhabiting fungi related to silvicultural management intensity in beech forests in southern Germany

Current silvicultural treatments in beech forests are aimed at achieving thick logs without discoloured hardwood. Therefore intensive thinning is applied already in younger stands with the objective of large-sized trunks at an age of 100 years. However, this approach bears the risk that dead wood structures and broken trees are completely removed from the forest. The impact of three different silvicultural management intensity levels on wood-inhabiting fungi over decades was investigated in a large beech forest (>10,000 ha) in southern Germany in 69 sampling plots: A Intensive Thinning and Logging with high-value trees, B Conservation-Oriented Logging with integration of special structures such as dead wood and broken trees and C Strict Forest Reserves with no logging for 30 years. The analysis of community showed marked differences in the fungus species composition of the three treatments, independent of stand age. The relative frequencies of species between treatments were statistically different. Indicator species for naturalness were more abundant at sites with low silvicultural management intensity. Fomes fomentarius, the most common fungus in virgin forests and strict forest reserves, is almost missing in forests with high-management intensity. The species richness seemed to be lower where intensive thinning was applied (P = 0.051). Species characteristic for coarse woody debris were associated to low management intensity, whereas species with a significant preference for stumps became more frequent with increasing management intensity. A total amount of dead wood higher than 60 m³/ha was found to enable significantly higher numbers of species indicators of naturalness (P = 0.013). In conclusion, when applying intensive silvicultural treatment, the role of dead wood needs to be actively considered in order to maintain the natural biocoenosis of beech forests.     

A quantitative approach to cork oak forest management

Mathematical programming is one quantitative technique that can be used for strategic and tactical natural resources planning. It has been extensively used both at private and public forest planning levels. Nevertheless, most applications concentrate on modelling of systems involving timber harvesting. This paper focuses on cork oak (Quercus suber L.) forest management. It summarizes the methodology to follow in order to generate information needed for modelling purposes. It formulates a cork oak forest management problem using a linear programming model. A case study is used to illustrate the procedure used. The results of the research on a modelling approach to cork oak forest management for an area extending over 5272 ha in the Portuguese submediterranean ecological region are presented. Extensions to this study are identified.     

A decision support system to simulate and compare silvicultural scenarios for pure even-aged larch stands

In sustained forest management, it is particularly useful to test the adequacy of various silvicultural scenarios, but decision-making is also becoming increasingly complex because forest managers have to simultaneously meet several different objectives in response to society demands. In order to help forest managers make appropriate choices in silvicultural systems, we propose a SDSS (Silvicultural Decision Support System) that applies to pure and even-aged larch stands (Larix sp.) in lowland areas where site conditions are similar to those encountered in Southern Belgium. Its main purpose is (i) to predict the influence of silvicultural treatments on stand evolution and (ii) assist forest managers in comparing different scenarios with respect to predefined goals. This SDSS consists in three modules designed to elaborate silvicultural scenarios involving (i) stand growth prediction and thinning simulation; (ii) assessment of indicators selected to define the scenarios referring to wood production, financial, technico-economic and ecological components, tree stability and wood quality; and (iii) comparison of the scenarios on the basis of the set of previously assessed indicators (multi-criteria analysis). User-friendly “MGC_Larch” software helps managers to formulate, evaluate and compare different silvicultural scenarios for larch.     

An enterprise architecture approach to forest management support systems design: an application to pulpwood supply management in Portugal

A key requirement for the success of a forest management information system is that it may effectively address its users?? needs. Yet, the development of models and methods to address-specific forest ecosystem management processes has not been matched by architectures that may take into account the human dimension of information systems. This paper presents an approach to pulpwood supply system architecture. Emphasis is on participatory business modeling that may effectively address users?? needs and enhance system resilience. An Enterprise Architecture methodology is proposed so that the information systems?? functional requirements for pulpwood supply may emerge from business and information architectures in workshops with the stakeholders. Results of its application to a vertically integrated Portuguese pulp and paper company are presented. The case study focuses on processes and business information required to support the pulp mills entire pulpwood supply management. Results show that the proposed approach addressed effectively end-users?? involvement in pulpwood supply system design. It provided an architecture that addresses all stakeholders?? perspectives and concerns and it was thus instrumental to develop a Pulp and Paper Supply Chain Process Framework. Results further show that it may effectively identify and integrate information systems?? components, ensuring business information integrity.     

A variable-based approach to the design, development, implementation and institutionalization of information systems in the forest sector

Global concern for improving governance in the forest sectorhas encouraged funding agencies and governments to spend millionsof dollars to harness the potential of computer-based informationsystems (IS) in improving the delivery of goods and servicesto stakeholders. Though design methodologies being used fordeveloping IS are technically sound and well established, stillthese systems are not being accepted by all the user groups.This has necessitated research on improvement of design methodologiesand related aspects. The present paper examines the successof an IS introduced in the Uttar Pradesh Forest Department in2002 in relation to 13 factors such as training, resource allocationand support of top management. The most important factors responsiblefor the success of an IS were found to be perceived usefulnessof the IS and resource allocation. A variable-based approachsuperimposed on existing design methodologies is expected toimprove the design, development, implementation and institutionalizationof IS in the forest sector.     

A bordered matrix approach to the bioeconomic modeling of agroforestry systems

A bordered matrix approach was developed as a technique designed to model multi-canopied agricultural or forestry production systems to find the optimal planting pattern and density meeting specified economic criteria. The approach uses monocultural production functions as a base from which to estimate polycultural production levels. A banana-cassava mixture is modeled to demonstrate how the technique can be applied.     

A four-stage approach to evaluate management alternatives in multiple-use forestry

A multiple-use forest management method is developed to support decisions on insect control in state forests of a case area in Central Poland, aiming at optimisation in a socio-economic context. The model is closely linked to the specific planning situation, but its structure is adaptable to other cases of optimal decision-making on multiple-use forestry. It is a four-stage consecutive model incorporating: (i) financial value of timber production; (ii) stage (i) plus the dual value of non-market outputs; (iii) stage (ii) plus the social value of carbon storage; and (iv) stage (iii) plus the social value of recreational benefits. That is to say, the complete model covers four important multiple-use outputs of the case area. The geographical distribution of high-priority protection forest resources is very sensitive to the stage-wise application of the model, especially with respect to recreation, providing innovative decision support related to multiple-use in a socio-economic context.     

A general framework for the quantification and valuation of ecosystem services of tree-based intercropping systems

This study provides the first complete framework for the valuation of ecosystem services of agroforestry and uses a tree-based intercropping (TBI) system in southern Québec, Canada, as a case study. Ten ecosystem services were estimated, all of which were of interest and directly applicable to most agricultural systems worldwide: nutrient mineralization, water quality, soil quality, pollination, biological control, air quality, windbreak, timber provisioning, agriculture provisioning, and climate regulation. A mix of mathematical models for the quantification and economic valuation of various ecosystem services were used. The results revealed a total annual margin of $2,645 ha^?1 y^?1 (averaged over 40 years). The economic value of combined non-market services was $1,634 ha^?1 y^?1, which was higher than the value of marketable products (i.e. timber and agricultural products). An analysis of the present value suggested that agricultural products ranked highest among the ecosystem services taken singularly, followed by water quality, air quality, climate regulation, and soil quality maintenance. Total economic value of all ecosystem services for the rotation period was $54,782 ha^?1, only one third of which was contributed by agricultural products. Although the total value of the ecosystem services provided by TBI was high, farmers only benefited from agricultural and timber products. Thus, government incentives are needed to interest farmers in adopting practices that benefit society as a whole.