As noted in the main text, the research described here was designed to support the sustainable forest management (SFM) in the study areas. Following Nussbaum and Simula (2005), the research considered SFM to represent a form of integrated land-use planning. In this respect, the concept of SFM extends beyond the sustainable management of individual forest stands to embrace the sustainable management of forested landscapes, including spatial attributes such as the size and connectivity of forest patches. The principal focus of the research was maintenance of forest biodiversity, which is widely acknowledged to represent one element of SFM approaches. A comprehensive treatment of SFM would encompass other environmental aspects, such as maintenance of soil fertility and water quality, as well as social and economic issues (Nussbaum and Simula 2005). The research presented here therefore only represents a partial contribution to the development of SFM approaches in the study areas. Development of a comprehensive approach would require further development of the ‘toolkit’ employed to date, to include these other elements.Golicher, D., and A. C. Newton. 2007. Applying succession models to the conservation of tropical montane forest. Pages 200-222 in A. C. Newton, editor. Biodiversity loss and conservation in fragmented forest landscapes. The forests of montane Mexico and temperate South America. CABI, Wallingford, Oxfordshire, UK.
One of the key findings of the current research was that current approaches to land use are not sustainable in any of the study areas. Livestock grazing, use of fire, and harvesting of trees for timber and fuelwood were widespread throughout the study areas, and are responsible for widespread forest loss and degradation. Additional threats to native forests were specific to particular study areas, such as the establishment of plantations of exotic tree species in Chile and shifting cultivation in parts of Mexico. The tools employed by the research enabled substantial impacts of such human activities to be identified, on the spatial characteristics of forest landscapes, the structure and composition of forest stands, and elements of biodiversity including species richness and genetic variation. These impacts were documented through the implementation of specific research themes (Figure 2), designed to address the ecological processes identified in the underlying analytical framework (Figure 1), through use of different elements of the toolkit.
Research also examined the process of forest recovery following disturbance, through the analysis of successional chronosequences and disturbance gradients, and through exploration of models of forest dynamics. Results highlighted the low rate of recovery in all of the forest communities examined, indicating that timescales of centuries would be required to re-establish the characteristics of old-growth native forest. These findings were consistent with the result of field observations, indicating that current land use approaches are leading to the progressive elimination of forest with old-growth characteristics from the landscapes studied. In particular, this involves the loss of large, shade-tolerant, late-successional trees and the species that they support.
Implementation of SFM approaches therefore needs to involve development of a sustainable land use strategy, to ensure that the biodiversity associated with native forests is maintained. Three potential response options could form elements of such an SFM approach, namely forest protection, restoration or sustainable use. As the research focused on forest landscapes situation outside protected areas, the ‘protection’ option received relatively little attention. Forest restoration is a highly novel approach for the study areas examined; many of the actions undertaken during this research initiative represented the first attempts to restore the forest types concerned. Here the future challenge is to extend restoration activities beyond the scale of experimental studies, towards the restoration of forest landscapes, an approach being explored in current research (Newton 2008b). Large-scale forest restoration efforts may result in significant costs to landowners and other stakeholders, and therefore the analysis of the potential costs and benefits of forest restoration is a research priority, to enable cost-effective restoration priorities to be identified. The toolkit is therefore currently being extended to include tools for mapping and valuing the ecosystem services provided by forests to human communities, together with the costs of restoration actions. These could then be explored with tools such as spatial multi-criteria analysis, to identify priority areas for restoration to be identified (Newton 2008b).
Research also examined the sustainable harvesting of tree species as a potential response option. In particular, the ‘conservation-through-use’ approach was examined, as in recent years it has attracted widespread interest, particularly in the context of tropical forest conservation (Neumann and Hirsch 2000). This approach is based on the contention that forests can be conserved if rural communities gain some direct economic benefit from harvesting forest products. In the current research, a range of tree species were examined in detail to test the validity of the ‘conservation-through-use’ approach, supported by the use of population viability modelling (Newton 2008b). Results highlighted that tree species are subjected to a variety of different threats, which often act in combination. For conservation action to be effective, all relevant threats must be addressed. In order for the ‘conservation-through-use’ approach to be effective, the income derived from sale of forest products should be used to protect the forest against other threats, such as fire, grazing by livestock or conversion to agriculture. Research indicated that this is rarely achieved in practice (Newton 2008b). The development of SFM approaches based on sustainable harvesting will therefore depend on the forest being protected from the many other threats identified during this research. In addition, appropriate silvicultural approaches will need to be identified for the tree species concerned.
In southern Chile, some 55% of the native forests have been substituted by exotic plantations (Lara et al. 1999), mostly established during the past three decades following the introduction of financial incentives for plantation establishment. In addition, native forests have often been degraded through high-grading, i.e. selective cutting of the largest and best-formed trees. To address this, there have been repeated calls for a new forestry legislation that could foster the sustainable management of remaining native
forests. According to the ‘conservation-through-use’ approach, this could increase their economic value and prevent further loss to other land uses. However, management of evergreen temperate rain forest is considered to be challenging, because of the relatively high structural complexity and tree species richness, and its dependence on biotic interactions for pollination and seed dispersal (Rüger et al. 2007). During recent decades, pilot silvicultural experiments have explored the recovery of evergreen rain forests from timber harvest, and strip-cutting and selective logging have been identified as potential management options (Rüger et al. 2007). However, the design, execution and monitoring of large silvicultural experiments remains costly and operationally difficult. Modelling approaches were therefore employed to assess the long-term consequences of different management options and to provide guidelines for forest managers aiming at reconciling conservation and production objectives (Rüger et al. 2007). The logging strategies that were simulated are either practiced by small forest owners or companies (selective logging) or were suggested to promote the regeneration of light-demanding species after harvesting (strip-cutting) (Rüger et al. 2007).
In Mexico, in the 1950´s a single silvicultural system was mandated by law for any type of forest management in the country, regardless of the characteristics of the forest, which consisted of a polycyclic, selective, diameter-limit harvesting regime (Segura 2000). This resulted in widespread high-grading of native forests. After the mid 1970´s the application of silvicultural regimes was deregulated, and a range of different silvicultural methods were introduced in different parts of the country, focusing on even-aged management and natural regeneration. However, the selective cutting system is still being widely used (Segura 2000). Very few native forests in Mexico are currently being managed on a sustainable basis for timber production, at least within the study areas examined by this research. In Mexico, model simulations focused on patch clearfelling, which represents a traditional form of forest use, involving slash-and-burn clearance of patches of around one hectare for timber extraction combined with short-term rotational planting of maize. Additional simulations focused on the clearance of small patches of forest at random intervals of time, a pattern typical of areas that are used by indigenous communities for timber and fuelwood production. This simulation results in a form of “dynamic equilibrium” being established after around twenty five years of succession. Both pines and oaks constantly regenerate under this regime, which allows light to reach the forest floor. Some of the more shade-tolerant broadleaved species can establish under this regime of low level disturbance, providing an external seed source is assumed to exist (Golicher and Newton 2007).
Further modelling activities focused on the extraction of fuelwood, one of the main uses of Mexican montane forests by simulating the potential long-term impacts of repeated harvesting of single trees (Rüger et al. 2008). A wide wide range of possible harvesting scenarios were explored, differing in wood volume harvested and preferred tree species and sizes. Results showed that the overall impact on forest structure and community composition increased linearly with the amount of harvested wood volume. Even at low levels of harvesting, forest size structure became more homogeneous in the long term because large old trees disappeared from the forest, but these changes might take decades or even centuries. Although recruitment of harvested species benefited from harvesting, species composition shifted to tree species that are not used for fuelwood. These results could be used to support the design of management strategies for the natural species-rich forests that achieve a balance between economic needs and ecological goals of the stakeholders (Rüger et al. 2008).
These examples illustrate how the toolkit for SFM has been developed to date, and applied to the different study areas. One of the key features of the toolkit approach is its flexibility; different models and other analytical tools can be applied in various combinations to address the specific characteristics and management issues of different study areas. However, development of the toolkit represents a ‘work in progress’; there remains scope for increased integration of its various elements, for example by further loose-coupling of models. This is being explored in current research, where raster maps of forest loss, fragmentation and condition derived from remote sensing imagery and linked to statistical and rule-based models, are being further coupled with the landscape-scale forest model LANDIS II, spatial MCA approaches and Bayesian Belief Networks (Newton 2008a). Such integration will enable priority areas for different management actions to be identified, to support the development of spatial planning approaches for the selected landscapes. This approach is entirely consistent with the conception of SFM approaches being a form of integrated land-use planning (Nussbaum and Simula 2005), and is designed to support efforts to implement such planning.
Lara, A., M. E. Solari, P. Rutherford, O. Thiers, R. Trecaman, R. Molina, A. R. Prieto and C. Montory. 1999. Cobertura de la vegetación original de laEcoregión de los bosques valdivianos en Chile hacia 1550. WWF-Universidad Austral de Chile, Valdivia.
Neumann, R.P. and E. Hirsch. 2000. Commercialization of non-timber forest products: review and analysis of research. CIFOR, Bogor, Indonesia.
Newton, A. C. 2008a. Restoration of dryland forest in Latin America: the ReForLan project. Ecological Restoration 26(1):10-13.
Newton, A. C. 2008b. Conservation of tree species through sustainable use: how can it be achieved in practice? Oryx 42(2):195-205.
Rüger, N., A. G. Guitierrez, W. D. Kissling, J. J. Armesto and A. Huth 2007. Ecological impacts of harvesting options for temperate evergreen rain forest in southern Chile - a simulation experiment. Forest Ecology and Management 252(1-3): 52-66.
Rüger, N., G. Williams-Linera, W.D. Kissling, W.D. and A. Huth. 2008. Long-term impacts of fuelwood extraction on a Mexican cloud forest. Ecosystems 11: 868-881
Segura, G. 2000. Mexico's forest sector and policies: a general perspective. Constituting the Commons: Crafting Sustainable Commons in the New Millenium, the Eighth Conference of the International Association for the Study of Common Property, Bloomington, Indiana, USA, May 31-June 4. http://dlc.dlib.indiana.edu/archive/00000341/.