Difference between revisions of "Forest management"

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|KeyReference=Arets et al, 2011
 
|KeyReference=Arets et al, 2011
 
|InputVar=Timber demand; Demand for traditional biomass; Fraction selective cut;Land cover, land use - grid;  
 
|InputVar=Timber demand; Demand for traditional biomass; Fraction selective cut;Land cover, land use - grid;  
Carbon pools in vegetation, soil and timber - grid; Fraction cut down; Forest plantation demand; Suitability rules;  
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Carbon pools in vegetation, soil and timber - grid; Fraction cut down; Forest plantation demand; Suitability rules; Harvesting efficiency;  
 
|Parameter=Fraction from non-forested land;
 
|Parameter=Fraction from non-forested land;
 
|OutputVar=Timber use fraction; Forest residues that remain in forest grid; Forest management type - grid; Area Regrowth forest - grid; Area degraded forest -grid; Timber harvest - grid;
 
|OutputVar=Timber use fraction; Forest residues that remain in forest grid; Forest management type - grid; Area Regrowth forest - grid; Area degraded forest -grid; Timber harvest - grid;

Revision as of 17:48, 25 March 2014

Forest management module in IMAGE 3.0
Flowchart Forest management. See also the Input/Output Table on the introduction page. The option of forest plantations in IMAGE and LPJmL is still under development, and expected to be available soon.

Key policy issues

  • How can management influence forest capacity to meet future demand for wood and other ecosystem services?
  • What are the implications of forest management for pristine and managed forest areas, and on biomass and carbon stocks and fluxes of relevance for climate policy?
  • What are the prospects for more sustainable forest management and the role of production in dedicated forest plantations?

Introduction

Global context

The world’s total forest area and other wooded land area of 2010 was estimated at just over 40 and 11 million km2 , respectively (FAO, 2010). People use these forests as resources for a multitude of purposes, such as for timber, fuel, food, water and other forest-related goods and services. Notwithstanding the undisputed market and non-market value of forests, the total global forest area continues to decline, with distinct differences between world regions. Total global deforestation has decreased over the last decade, but still occurs at a significant scale in large parts of Latin America, Africa and Southeast Asia. At the same time, net forest expansion takes place in other regions, such as in Europe and China. Agricultural expansion is the main pressure that drives deforestation. In addition to the loss of forest area, degradation processes and a decline in the supply of services may occur as a result of the human use of forests. Managing global forest resources in a sustainable way may help to preserve forests, slow down or reverse the degradation process, while conserving their biodiversity and carbon stocks (FAO, 2010).

Several types of forest management systems are in use to meet worldwide demand, for timber, paper, fibre board, biofuel and other products. Management practices depend on forest type, conservation policies and regulation, economics, and other –often local– factors. Practices differ with respect to the volume of wood harvested per area, the rotation cycle and the carbon content and state of biodiversity of the forested areas. Harvested wood is used for various purposes, such as for timber, pulp, paper, traditional fuel wood and modern forms of bio-energy.


Forestry in the IMAGE 3.0 model

Because of the importance of forest management for the functioning and state of forests, its modelling has become an integral part of the IMAGE 3.0 model. The model simulates an forest area in 2010 of total about 46 million km2. As such the area is somewhat larger than observed, due to the fact that the model does not include other wooded land (see Carbon Cycle and Natural Vegetation module for details). To manage these forests three types of systems are defined in IMAGE 3.0 as a simplification of the whole range of existing forest management systems (Carle and Holmgren, 2008; Arets et al., 2011). The purpose of Sustainable Forest Management (SFM) is to preserve forests and their production capacity and biodiversity for future generations, and to counteract forest degradation processes. In IMAGE, several elements of SFM can be included, subject to policy options, consisting for example of shifts in the mix of forest management systems.

The first type of forest management included in IMAGE, is that of clearcutting (or clearfelling). This is a management system by which all trees in an area are cut down, after which regrowth can take place, either naturally or ‘assisted’. It is applied often in temperate regions, where stands are often monocultures of specific endemic species.

The second type is that of selective logging, in which only the trees with the highest economic value are felled. This is more common in tropical forests with a high heterogeneity of tree species. Reduced impact logging (RIL) is an ecological variant of selective logging, to reduce harvest damage, stimulate regrowth and maintain biodiversity levels (Putz et al., 2012). As such, the RIL system is a more ecological and sustainable forest management system, which is promoted under SFM schemes.

The third system is that of forest plantations, such as hardwoodtree plantations in the tropics and poplar plantations in temperate regions. Selected tree species, either endemic or exotic to the area, are planted and managed more intensively – for example, through irrigation and fertilizer use – to maximise production and/or wood quality. After the trees are harvested, new ones are planted, and management is put in place. Forest plantations generally have a high productivity level (Del Lungo et al., 2006). By producing more wood and wood products on less land, plantations may contribute to more sustainable forest management by reducing the pressures on natural forests (Carle and Homgren, 2008; Alkemade et al., 2009). At the same time, the ecological value of biodiversity in many forest plantations is relatively low (Hartman et al., 2010).

Input/Output Table

Input Forest management component

IMAGE model drivers and variablesDescriptionSource
Forest plantation demand Demand for forest plantation area. Drivers
Fraction of selective logging The fraction of forest harvested in a grid, in clear cutting, selective cutting, wood plantations and additional deforestation. Fraction of selective cut determines the fraction of timber harvested by selective cutting of trees in semi-natural and natural forest. Drivers
Harvest efficiency Fraction of harvested wood used as product, the remainder being left as residues. Specified per biomass pool and forestry management type. Drivers
Timber demand Demand for roundwood and pulpwood per region. Drivers
Carbon pools in vegetation - grid Carbon pools in leaves, stems, branches and roots). Carbon cycle and natural vegetation
Demand traditional biomass Regional demand for traditional bioenergy. Energy demand
Land cover, land use - grid Multi-dimensional map describing all aspects of land cover and land use per grid cell, such as type of natural vegetation, crop and grass fraction, crop management, fertiliser and manure input, livestock density. Land cover and land use
Land suitability - grid Suitability of land in a grid cell for agriculture and forestry, as a function of accessibility, population density, slope and potential crop yields. Land-use allocation
External datasetsDescriptionSource
FAO deforestation rates Historical deforestation rates according to FAO. FAO
Traditional biomass from non-forest land Fraction of traditional fuelwood from non-forestry sources, such as orchard, assumed to be 50% (low-income countries) and 68% (middle-income countries). FAO

Output Forest management component

IMAGE model variablesDescriptionUse
Harvested wood Wood harvested and removed.
Forest management type - grid Forest management type: clear cut, selective logging, forest plantation or additional deforestation.
Timber use fraction Fractions of harvested timber entering the fast-decaying timber pool, the slow-decaying timber pool, or burnt as traditional biofuels.
Regrowth forest area - grid Areas of re-growing forests after agricultural abandonment or timber harvest.
Degraded forest area Permanently deforested areas for reasons other than expansion of agricultural land (calibrated to FAO deforestation statistics).
Forest residues Harvest losses (from damaged trees and unusable tree parts) or harvest residues that are left in the forest by purpose because of environmental concerns. These losses/residues remains in the forest after harvest, in in principle enter the soil pools. But they could also be used for other/energy purposes. Final output