Sustainable Forest Management in the Tropics – Still a Long Way to Go?

Abstract

Deforestation in tropical countries is still an important issue for many countries with significant forest areas in these regions. In times of serious discussion about climate change and global warming, public interest in this topic is very high. One of the solutions to the problem of deforestation activities is to use forests in a sustainable way, but a great deal of research is still needed before realize sustainable forest management in tropical rainforests is possible. This chapter starts with a discussion of the technical terms often used in connection with silviculture in the tropics. It then continues by giving an overview about the principles of existing management systems and then evaluates these in relation to their impact on sustainability. Finally, in a case study of the Amazon region, the impact of a commonly used reduced-impact logging system is presented and evaluated by examining its impact on economic and ecological sustainability.

Deforestation

Tropical rainforests play an important role in climatic cycles, forming a precious cooling band around the Earth’s equator. The ongoing destruction of large forest areas is increasingly being recognised as one of the drivers of climate change. Carbon emissions from deforestation are considered to be higher than those caused by households, traffic, and industry.

The factors affecting deforestation in developing and emerging countries are complex. Perhaps the most significant is population growth and the related rise in demand for agricultural land (for both subsistence and commercial cultivation) and pasture. Another pull factor is the growing pressure on forests to supply energy wood. Finally, the use being made of the high values stored in the forests such as timber and diverse non-timber forest products has also gone up dramatically in recent years.

In many cases, the underlying causes for forest loss can be reduced to the simple link between poverty and deforestation. Countries with large rural populations and low household incomes (GNP per capita) are very likely to have high deforestation rates. Forests are converted because the present value of the harvest is expected to be higher than the incoming flow of future forest-based revenues.

Perhaps surprisingly, a factor identified as possibly contributing to the improvement of the situation is to be found in labour practices. Vanclay and Nichols (2005) have postulated that the promotion of alternative employment opportunities would play a particularly important role in halting – or at least slowing – deforestation.

In Fig. 1, the natural net change in forest area by region is shown for the periods from 1990 to 2000 and 2000 to 2005.

Fig 1

Annual net change in forest area by region (2 periods:1990–2000 and 2000–2005). Source: FAO Forest Resource Assessment 2005 (see Color Plates)

The highest deforestation rates can be found in Africa, where more than 4.2 million hectares per year have been clear-cut, whereas only an insignificant number of forests was planted or regenerated naturally. In the period from 2000 to 2005, the clear-cut area was slightly reduced.

Africa is followed by South America, where annual deforestation in the Brazilian Amazon, with more than 20,000 km², led to considerable forest loss (close to 4 million hectares per year with an increasing tendency in the last 5 years of the observation period). Some areas were re-forested or afforested with tree plantations.

In Asia, the current deforestation rate of natural forests is rather low. This is due to the extremely high deforestation in the past. Only a few pristine forests are left in remote areas with restricted access. The shortage in wood and the high demand for wood from other Asian countries led to the establishment of a remarkable forest plantation estate before the 1990s. Due to high activities in this sector, the net loss of forest area is the lowest of all regions with tropical rainforests, comparable to North and Central America or Oceania.

Europe, in contrast, is the only region where net forest area is increasing, which is mainly due to forest establishment in low-productive agricultural areas.

A closer look at deforestation and the respective land-use change reveals that the net loss of forest area occurs most frequently in the tropical regions (Fig. 2).

Fig. 2

Balance between loss of native forests, forest plantations and other land-uses. Source: FAO Global Forest Resource Assessment (2000) (see Color Plates)

From 1990 to 2000, 14 million hectares of forests per year were lost due to conversion into other land uses. Only 1 million hectares per year of this area is re-gained by forest ecosystems due to natural reforestation (succession) and another 1 million hectares by forest plantation establishment. A significant area of 8 million hectares of forest plantations annually has been established on agricultural and pastureland. Because of this, forest plantations in tropical regions have increased by 20 million hectares in the decade from 1990 to 2000.

Looking at land-use change in tropical regions, differences between the continents can be detected (Fig. 3). In Africa, 60% of the deforestation area was directly converted to small-scale permanent agriculture. In Latin America, however, nearly 50% was converted to large-scale permanent forests, followed by gains in land for stock farming and small-scale permanent agriculture.

Fig. 3

Changes in forest area into other land-use forms by continent (FAO 2000) (see Color Plates)

In Asia, close to 30% was also converted to large-scale permanent agriculture and another 25% to other uses (mainly pasture), but with more than 20%, the intensification of shifting cultivation is also important to mention. In the pan-tropical regions, direct conversion to large-scale permanent agriculture, pasture and other land uses, as well as direct conversion to small-scale permanent agriculture, have remained nearly constant.

To summarize, it can be stated at that:

• At a global level, direct conversion of forests to permanent agricultural land is of higher importance than intensification of shifting cultivation.

• In Latin America, conversion of large areas for permanent agriculture and pasture dominates, whereas in Africa, conversion into small-scale agriculture is of high importance.

• In Asia, a twofold development can be observed: on the one hand, the area of migrating agriculture (in pristine forests) is increasing, whereas, on the other hand, more and more shifting cultivation farmers are staying permanently on their areas. After net losses in the 1990s, Asia experienced net gains of forests in the observation period of 2000 to 2005, manly due to large afforestations in China.

It appears that land-use options with non-destructive consequences for forests are urgently needed. One of the options could be to make use of the forest itself as a natural resource by managing it in a way that ensures the most important economic, ecological, and social functions (Sustainable Forest Management, SFM). If this is to be achieved, identification of the circumstances that foster sustainable forestry is an absolute requirement.

The Principles of Sustainable Forest Management

Terms Commonly Used in Tropical Forest Management

In many publications dealing with SFM, terms are used that are not directly linked to sustainability in the strict sense. These have to be highlighted and explained in order to avoid misunderstandings or misinterpretation.

One of the most common terms in tropical forest management is selective logging. Synonyms are migrant logging, unregulated timber extraction, and conventional logging. The aim of this management form is to use forests for fast wood delivery to the market, aiming at short-term maximization of economic benefits, often without any government control. Another frequent term is sustainable timber management, which means the long-term use of timber, disregarding other aspects of sustainability. Finally, the term sustainable forest management (SFM) or multiple-use forestry has been created to encompass economic, ecological, and social sustainability in forest management. This concept includes reduced-impact logging (RIL). In the third section of this article, we present a case study on RIL in northeast Brazil showing that environmentally sound harvesting techniques are one of the keys to successful management in tropical forests.

SFM denotes management of forests according to the principles that guarantee sustainable development. Sustainability in this context is threefold, including social, economic, and ecological goals. In the last decade, continuous research efforts have led to the availability of a broad range of methods and management tools that have already been tested in practical forestry.

A first international endeavour to adapt forest principles was at the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro, Brazil in 1992. At this conference, the general international understanding of SFM was captured. It turned out that forest ecosystems are so complex and diverse that if management practices follow the rules of SFM, there is no “standard” set of criteria and indicators that can be used to evaluate different regions. In the decade after Rio, the sets have been continuously adapted and diversified to meet the requirements of sustainability in forestry practices at all levels and regions.

Currently, one of the most widely accepted definitions of the term SFM is that developed by the Ministerial Conference on the Protection of Forests in Europe (MCPFE), which has been adopted by the Food and Agriculture Organization (FAO) in Rome. It defines SFM as ‘the process of managing permanent forest land to achieve one or more clearly specified objectives of management with regard to the production of a continuous flow of desired forest products and services without undue reduction in its inherent values and future productivity and without undue undesirable effects on the physical and social environment’ (ITTO 2006).

The definition is based on the balance among the social, economic and ecological demands (‘triple bottom line’, Vanclay and Nichols 2005) of the society for forests. On the one hand, society depends on a variety of products delivered by forests; on the other hand, the demand for land uses other than forests is high. In the face of this dilemma, forest managers have to find a way to ensure the multiple use (health and productivity, social values) of managed forests for future generations. SFM plans therefore can no longer be developed without considering the needs, wishes, and demands of a broad community of stakeholders.

In a rapidly changing world whose social, economic, and environmental framework is in constant flux, SFM is likewise subject to permanent change and adaptation. Nevertheless, research and technical development must be implemented in a way that constantly guarantees the use of the resource “forest” in a commonly agreed-upon sense.

In order to access and reporting about SFM in a comparable way, policy instruments had to be developed. This was done by identifying criteria (C) that define essential elements of SFM and periodically measured indicators (I), revealing the direction of development of each criterion.

After years of consultation, growing consensus emerged among international experts on the most important elements of SFM, with seven thematic areas being identified:

• The extent of forest resources

• Biological diversity

• Forest health and vitality

• Productive functions of forest resources

• Protective functions of forest resources

• Socio-economic functions

• Legal, policy, and institutional framework

For further remarks on the current status on C and I in Europe, see Köhl and Rametsteiner in the present volume.

Land Tenure and Utilization of Tropical and Subtropical Forests

One of the oldest and most common systems for tropical rainforest use on larger scales is forest concession management. Instead of selling public-owned land, in concessions, private companies are given the right to utilize a pre-determined forest area by government authorities. In return, the state receives royalties or concession fees.

In the 1980s, about 80% to 90% of the timber coming from tropical forests was harvested in concessions. Concession areas can be up to 1 million hectares or more and are generally granted to companies for periods between 1 and 40 years, though cases exist where concessions have lasted as long as 99 years. Although in the past concessions were frequently assigned arbitrarily with no bidding process, currently, the most common procedure is auctioning.

For a long time, interventions in forest concessions were based on selective harvest operations, i.e. merchantable timber above a pre-defined minimum cutting diameter was removed without caring for forest improvement (‘log and leave’). The focus of forest intervention was very much on short-term profits rather than on long-term sustainable harvest yields and maintenance of forest structure. The reason for this pure-profit-seeking mentality was the predominance of short utilization periods with a lack of planning reliability, unclear contract conditions, poor enforcement, and virtually no control. Thus, the long-term consequences of the concession policies in many tropical countries were degradation and often conversion of existing forests, leading to other land-use forms like agriculture, stock farming, and industrial plantations. This situation has partially changed. In several countries, e.g. Côte d’Ivoire, concession holders today have to present a forest management plan that includes reforestation schemes and investments for the rural populations. This supports a long-term engagement of the companies involved. As a result, today a considerable area of tropical forests in concessions is deemed to be under SFM (e.g. > 1 mill. ha in Northern Congo-Brazzaville, ITTO 2006).

Real land tenure is also an incentive to handle the production base carefully as the source of future income. Many forest landowners are therefore interested in maintaining the yield level in the second and subsequent harvesting cycles. On the other hand, private land ownership gives more rights to the owner in his decisions how to use the land, including transformation of forests into other land-use forms (e.g. in the Brazilian Amazon, landowners have the right to convert 20% of their forested property).

Small landowners generally seek a multiple use of their property, including agriculture, animal breeding, and agro-forestry. Forest management plans with inventories and other restrictions can often not be fulfilled by smallholders, thus pushing them into unsustainable use or illegality. Finally, government and authorities are often not able to monitor the large number of small landowners, resulting in possible deforestation and forest degradation. Actions that would encourage compliance with SFM might include payment of financial incentives, better inspections, and economically sensitive punishments.

Counterproductive to any type of SFM are the unstable political and legal situations in many countries with considerable tropical and subtropical forest areas. Without a stable framework, long-term planning and activities are displaced by short-term actions to get fast cash. This is especially the case where conflicts occur or failing state structures exist (Angelsen and Kaimovitz 1999).

Degraded and Secondary Forests

An increasingly important issue in tropical and subtropical forest utilization is the management of degraded and secondary forests. While most of the studies about SFM are focused on primary forests, a rather large area is already stocked with forest ecosystems heavily disturbed by human intervention. For decades, secondary forests in tropical and subtropical regions were largely neglected in forest policy and as a resource for forest management. According to the FAO (2005), the world’s degraded and secondary forests in the tropics have an area of 850 million hectares and provide a variety of products for poor rural populations. In this sense, they represent a ‘missing middle’ between undisturbed primary forests and afforestations and are important ‘safety nets’ for people in rural areas (Fig. 4).

Fig. 4

The missing middle: secondary forests between Protected Area Management and Afforestation (ITTO 2002 (see Color Plates)

According to the definition of the International Tropical Timber Organization (ITTO 2002), secondary forests are ‘woody vegetation regrowing on land that was largely cleared of its original forest cover’. Secondary forests emerge from the succession of degraded or devastated forests after uncontrolled conventional logging operations, utilization of fuelwood, or after other land-use forms like agriculture, shifting cultivation, and stock farming. According to the FAO, secondary forests (sf) can be classified as:

• Degraded sf

• Post-catastrophic sf

• Post-extraction sf

• Swidden fallow forests

• Post-abandonment sf

• Rehabilitated forests

Important characteristics of secondary forests are a more homogeneous structure, lower biodiversity (especially fewer tree species) than in primary forests, and the dominance of pioneer and light-demanding tree species. In general, the management systems are similar to the ones used in primary forests, however concrete management options are dependant on the grade of disturbance and structure of the secon­dary forests. The social framework is also frequently different from unexplored primary forest areas since people who have settled in these areas were forced to abandon their land because of degraded soils.

Management Systems for Tropical and Subtropical Forests

It is estimated that only 4% of the forest area in tropical and subtropical regions is managed in a sustainable way and not only by selective logging (FAO 2005). A survey conducted by ITTO in 2004 (Tomaselli and Tuoto 2004) revealed that numerous forest enterprises in Latin America are still working without management plan and are not yet certified.

Silvicultural management systems in the tropics have a long tradition and can be classified in two categories: monocyclic and polycyclic (see Table 1).

Table 1 Comparison between monocyclic and polycyclic systems

In the few non-explorative silvicultural management systems in the tropics and subtropics, polycyclic systems currently predominate. In these areas, in several interventions of low impact, marketable wood is harvested. An example is the Malaysian Selective Management System. All polycyclic systems aspire to provide multiple forest goods and services. Monocyclic or rotation management systems, however, are based on one single harvest operation at the time of timber maturity. The Malaysian Uniform System, a predecessor of the Malaysian Selective Management System in the tropical lowlands of the Malay Peninsula, is one of the most traditional monocyclic systems with an intervention cycle of 50–70 years.

In regard to management systems in tropical forests, a distinction can also be drawn among transformation, substitution, and improvement systems. Transformation systems are characterised by slowly converting the structure and species composition of a system to increase productivity and value (Lamprecht 1986). This can be done by cutting out non-commercial species, improvement thinnings, or regulating natural regeneration. In contrast, in substitution systems, undisturbed natural forests are replaced by artificial stands like plantations or enrichment plantings (see Fig. 5).

Fig. 5

Improvement thinning (acc. to Lamprecht 1986) and enrichment planting (photo from Tapajóz, Brazil) (see Color Plates)

Besides the above-mentioned Malaysian Selective Management System, other well-known transformation systems include the CELOS system, the Indonesian Selective Cutting (and Planting) System or the Tropical Shelterwood System.

Examples of substitution systems are the ‘Limba-Okumé’ or ‘Recrû’ methods applied in Africa. In these systems, Aucumea kleineana (Okumé) or Terminalia superba (Limba) are planted after clear-cut or conventional logging in natural forests. Moreover, slash and remaining trees are removed with heavy machinery or burned. Another type of substitution system is ‘Taungya’, the mother of all the modern agro-forestry systems. It was introduced in British India in 1886 by the German botanist Brandis. After clearing of the natural forests, teak (Tectona grandis) was established by seeding, in combination with agricultural crops like rice or corn. After a period of 1 year, when the shading of the trees no longer allowed cultivating agricultural crops, the areas were managed for forestry exclusively.

According to Lamprecht (1986), improvement (see Fig. 5) means to release desired trees in natural forests in order to increase growth rate or stem quality. A feature of enrichment planting involves the cutting of stripes into degraded (secondary) forests and planting them with valuable commercial species. The remaining forests give shelter to the young plants and preserve the main forest functions.

SFM in the Brazilian Amazon

Tropical and subtropical rainforests are extremely sensitive ecosystems in which all the ecological functions are interlaced. Any disturbance of this equilibrium may have future consequences that cannot be anticipated today. Managing such systems in an economically and ecologically sustainable way may result in severe conflicts. For an analysis of the economic sustainability, the productivity of the forests and possible management restrictions have to be emphasised. For most of the tropical rainforests, there is evidence that only low increments of commercial wood can be expected. The values are between 0.8 and 2.5, in very good conditions 3 m³/ha/year.

As minimum requirements for successful SFM in tropical forest Seydack (2000) outlines

• An optimum residual growing stock

• The derivation of rotation cycle and annual allowable cut

• Criteria for the harvesting of trees according to individual tree maturity

• Successful regeneration

The particular system prescribed for non-flooded Brazilian forests of the Amazon region is shown in Table 2 (adapted from Silva 1997). It is based on selective interventions required by Brazilian forest law, and it makes it possible to sustain the growing stock of the forests.

Table 2 Sustainable forest management system in non-flooded tropical lowland forests in the Brazilian Amazon

The damage in the remaining stands and therefore the impact of logging operations are closely related to harvesting intensity. The values reported range between 10% and 40% of the volume of the remaining trees that are damaged by felling or skidding operations.

The detailed data collection for inventory, operational planning, and the conduct of harvest operations according to the principles of reduced-impact logging (RIL) are time and cost intensive. Combined with the low increment per hectare and year, the allowable cut per hectare is very low. In a period of 25–30 years between two harvesting operations, about 30–60 m³/ha can be harvested in one intervention. In clearcuts of intensively managed forests, the value ranges from 250 to 600 m³/ha, reducing the harvesting costs significantly. Another aspect of low increment is the considerable area needed for supplying industry with roundwood. To feed a sawmill with a processing capacity of 60,000 m³/year, an area of 30,000–60,000 ha/year is necessary. Management plans have to be established and operational planning is necessary in the complete inventory area, increasing fix costs and overhead.

Another severe problem linked with SFM in the tropics and subtropics is how to maintain biodiversity in forest ecosystems. In a study of Maciel et al. (2002) on an area of 51 ha in the Amazon rain forest, 189 species of 135 genera and 46 families were found. In the entire area, only 7,000 trees had a diameter greater than 25 cm at breast height (dbh).

On average, only five trees per hectare had a dbh that exceeded 60 cm, which is considered the minimum for cost-efficient harvesting. Another restriction is that only 25–40 species are of commercial value; no use has been found to date for the others. This means that only the few individual trees of each species that have reached at least 60 cm dbh can be harvested and used. Furthermore, these trees are not equally distributed over the area, making piling according to sort impossible. The result of a harvesting operation is a very heterogeneous assortment of species, diameters, and quality. The latter is one of the main problems of logging in pristine forests: most of the bigger trees of sawlog dimension are already overaged and show decay and rot inside the stem. Most of the logs are devalued, reducing the quantity of commercial wood (Fig. 6).

Fig. 6

Defects of roundwood coming from tropical primary forests (see Color Plates)

Logging that focuses on a few commercial species, will eventually lead to a shift in species composition. In general, the trees of bigger dimensions are climax species. If they are removed, pioneer species regenerate more easily, but precisely these species are the ones of low or non-commercial value, which only over time periods of more than 100 years are replaced by climax species. Without intervention, in the harvesting periods in 30, 60, and 90 years, the stands will show a completely different species composition and diameter structure. This fact alone challenges the ecological sustainability of the management system. Since special species (umbrella/keystone species) play an important role in maintaining the biodiverstiy of the system, their loss would have severe consequences for the ecological balance and the functioning of the forests (→ redundant species hypothesis).

An important aspect of ecological sustainability is the impact of partially mechanized logging in tropical forests. Due to long and deep weathering, tropical forest soils are rich in clay. These soils are susceptible to compaction if heavy machines are used in logging operations. In particular, under wet conditions, soil compaction may cause severe disturbance in the forest ecosystem, reducing water conduction, nutrient transport, and rooting of the soils. Moreover, heavy erosion can take place on the forest roads and skidding trails. Therefore, harvesting operations should be limited to dry periods (Fenner 1996).

Reduced-Impact Logging (RIL) in the Brazilian Amazon – a Comparative Case Study

In Brazil, less than 10% of the logging operations are based on approved management plans. Furthermore, according to Lentini et al. (2003), more than 50% of the roundwood arriving at sawmills in the Amazon region is assumed to have come from illegal logging operations. There is evidence that environmentally sound logging operations contribute to improve forest management in the tropics (Holmes et al. 2002). In this section, the impact of RIL has been analysed in a case study conducted by the ORSA group in the Brazilian federal states of Pará and Amapá. ORSA is the biggest private landowner in the Amazon, with a property of 1.6 million hectares (Fig. 7).

Fig. 7

Location of the ORSA company in Northeast Brazil (see Color Plates)

In Brazil, only selective logging done according to the principles of SFM is allowed in natural forests (Silva 1997). For small farmers or communities, it is very difficult to obtain approval of a management plan due to high bureaucratic hurdles and the related expenses. This is one main reason why smallholders act illegally, thus contributing significantly to deforestation in the Amazon. In contrast, bigger companies, which contract lawyers and forest engineers, can easily meet the requirements for approval of their management plans.

About 550,000 ha of ORSA’s property is composed of natural forests under FSC certification and managed according to SFM principles. The company owns a sawmill that has recently been enlarged to process 120,000 m³ of roundwood per year. Harvesting operations are adapted to the volumes needed to assure the sawmill’s capacity.

The company’s areas are subdivided into six harvesting units, each containing five annual units where the harvesting volume of 1 year can be provided. Summing up all the annual units, the cycle for the second cut in each area is about 30 years (Fig. 8). The maximum allowable cut per hectare is thirty cubic meters, which means that the volume increment of commercial timber is estimated to be 1 m³/ha/year.

Fig. 8

Management and harvesting units of ORSA Florestal (see Color Plates)

The units are further subdivided into blocks of 4 × 4 km, where the operational units of at least ten ha (400 × 250 m) are marked for planning the harvesting operations in the field (Fig. 9).

Fig. 9

Operational units (10 ha) and study area (see Color Plates)

The management area of the company is subdivided into flat terrain on the plateaus and hilly terrain on slopes, with a maximum of 45% inclination. Terrain steeper than 45% is protected by law; therefore, no harvesting operations are allowed. The company’s management system follows the rules showed in Table 3. Harvesting and skidding operations and the respective damage are illustrated in Figs. 10–13.

Table 3 Comparison of area consumption between the different distances of a systematic system and the system of ORSA

Fig. 10

Skidder equipped with a winch for cable hauling (see Color Plates)

Fig. 11

Hauling of the logs by driving to the trees using a skidder with a grabber (see Color Plates)

Fig. 12

Damage at the remaining stand caused by felling and hauling operations (see Color Plates)

Fig. 13

Skidding trail of the ORSA system one year after logging operations (see Color Plates)

There are two possible hauling systems for flat terrain that are recognized as being of low impact and are therefore acceptable for SFM: One is to create systematic access to the area with permanent skidding lines, where the felled logs are hauled with a winch and taken to a log storage point with the skidder. In the other system, the skidder drives directly to the felled and bucked trees and takes the logs out with a claw. Both systems have advantages and disadvantages in regard to productivity, the area consumed by forest roads, and skid trails and possible damage.

The aim of the following study was to compare the two systems in regard to hauling capacity and area consumption. The first system requires permanent and systematic skidding lines in a defined distance where the skidder can move and pull out the felled logs. The other involves permanent secondary roads every 400 m connected to the primary road, where the skidder follows marked trails to the felled trees (see Fig. 15).

Fig. 14

Area consumption (absolute and relative), depending on the skidding-line system (systematic or direct to the tree). The absolute values refer to the total study area of 530 ha (see Color Plates)

The decision about the course of the skid trails is taken by the operational planners: they have maps of harvesting plots, which are subdivided into subplots of ten ha (400 × 250 m), where the trees to be felled are already marked. Considering the terrain and the location of the future crop trees, the skidding trails are marked in the field by forest engineers with the intention of having the lowest possible impact. At this step, the log storage points are also marked on the maps and the terrain.

In the present study, the operational maps with the hand-drawn skidding lines were scanned and the available information digitalized and put in the database together with the inventory data. Thus, primary and secondary forest roads, skidding lines, as well as location and felling direction of the trees were available in the geographical information system Arc-Gis^®. In a second step, the lines in the system marking the roads were buffered according to the information given by the company:

• Primary roads – 4.5 m each side (road width of 9 m)

• Secondary roads – 3 m each side (road width of 6 m)

• Skidding trails – 2 m each side (trail width of 4 m)

From the buffered roads and trails, the areas taken for the access infrastructure for harvesting operations could be calculated. The skidding system of the company was compared to a virtual systematic skidding line system that can be applied in flat terrain like that was found in the study area.

The virtual system consisted of several distances between the lines: 60, 80, 100, and 120 m. The longer the distances between the lines, the more the capacity to haul the logs with the winch and the area consumption for skidding trails decreased. The maximum distance for winch hauling was set to 60 m; over longer distances, the cable cannot be pulled by the forest workers in the understorey of tropical rainforests. Also, the pulling operations over such distances may cause significant damage to the remaining stand and the regeneration process. The practicability of 60 m winching was tested in a study in the early 1990s (Grammel 1990).

The results presented in Fig. 14 show a significant difference in area consumption for the presented options: For distances from 80 to 120 m between systematic skidding lines, area consumption is 2–4% less than in the system where the skidder drives directly to the logs. The two systems are only comparable if 60 m is left between the systematic skidding trails. Related to the study area of 530 ha, the numbers don’t seem to be particularly high. However, based on the total natural forest area of 550,000 ha certified by FSC, the productive forest area is reduced by 35,281 ha with the currently applied system and by only 20,755 ha if a systematic system with 100 m distance between the skidding lines is applied (Table 3). It can be stated that when using a systematic access system, the soil surface area affected by skidder operations can be reduced by more than 40%.

Fig. 15

Illustration of the two different skidding line systems (see Color Plates)

The advantage of a systematic and therefore permanent system would also be the higher independence of dry and wet seasons for logging operations because the skidding-line network is designed to be permanent for the subsequent harvesting operations every 30 years. Since the heavy machines driving into the stands have no direct impact, soil compaction and water conductivity will not be influenced in the same way.

Last but not least, is the question of why the company prefers to drive directly to the trees to haul the logs (Fig. 15, left). The answer can be found in the productivity of the selected system. The results in Fig. 16 make clear that driving to the tree and hauling it with a skidder equipped with a grabber is twice as productive as winch hauling.

Fig. 16

Hauling capacity of the different systems in m³/h (see Color Plates)

The reasons for the lower productivity are manifold. The cable of the winch has to be pulled out, and even with a hydraulic pulling assistance, it takes a long time to pull the cable through the stands. Then the cable has to be passed below the log, which in many cases is a time-consuming operation. After that, the line where the log is hauled has to be cleared, and in some cases, valuable future crop trees have to be protected to prevent them from being damaged.

According to Fig. 16, the productivity with a winch-hauling distance of 40 m (80 m distance between skidding lines) is about 14.5 m³/h, while the skidder with a grabber has a productivity of 29 m³/h. The two systems have to be evaluated carefully according to cost-benefit aspects as well as to the ecological impact of logging operations. A permanent systematic skidding line system has the advantage that the lines can be found again easily, even after 30 years, so the area consumption can be taken as fixed. With the system currently applied by ORSA, it is also intended to reuse the skidding tracks in the next rotation cycle as long as the trees to be logged are close to such a track. Since there are no cuts of trees and the tracks cannot be marked permanently, it is doubtful whether they can be found again after 30 years. This means an increase in the area driven over in subsequent rotations, with uncertain consequences for the ecosystem.

SFM – Still a Long Way to Go? A Synthesis

The perspectives of SFM in tropical and subtropical forests are manifold. Nevertheless, a great deal of effort is still necessary to guarantee the sustainable development of regions with considerable areas of natural forests. There are technical, environmental, policy, and social drivers that have to be considered to safeguard these unique ecosystems.

The process of establishing criteria and indicators of sustainability was a big step forward in the direction of SFM. The debates on C&I in the numerous national stakeholder meetings showed that forest-management techniques have to be adapted to the local conditions. This process helped to clarify the vital expectation of stakeholders towards their forests.

Currently, there is quite a solid knowledge base on SFM in the tropics and subtropics, meaning we can say that tropical forests can be managed in a way that ‘forest stays forest’ (Fig. 17). The most important lessons learnt from the past comprise items such as the usefulness of harvest control; the need for appropriate silvicultural operations; the need for science-based knowledge of species ecology, growth rates, and planning; skilled staff; and a permanent forest estate (see also Dawkins and Philips 1998).

Fig. 17

A view over primary forest. About 30m³/ha were taken out of this area the previous year (see Color Plates)

Nevertheless, as seen from the ongoing debate, some obstacles to the spread and implementation of SFM still have to be overcome.

First, there is the fundamental issue of competition for land. How many forests are needed to sustain the world’s demand for wood and how much agriculture is needed? According to Sayer et al. (1997), ‘much of the world’s forest is over-utilized and under-managed.’ As outlined above, average productivity in natural forests is rather low (around 1 m³/ha/year) in comparison to plantation forestry. Therefore, a slight production increase in natural forests could be one solution to reduce the area of over-utilized forests.

The motivation for maintaining natural forests in the future may be more due to a desire for amenities and environmental services, for NTFP and subsistence goods, than for timber. Timber from natural forests will increasingly compete with that of the expanding plantation forestry and its shifting production goals from pulpwood to clearwood.

Next, the technological progress made in the last few decades in regard to reducing environmental impacts, as shown by the case study in this section, provides great potential for optimisation of SFM. Damage to trees and the soil, breakage and waste, and capital intensity as well as operating costs can be reduced in an ongoing process of learning and development.

Technological progress outside SFM in terms of waste reduction in wood processing, or the utilization of a greater variety of species is another opportunity to improve management in existing areas of natural forests.

Last but not least, a lack of efficient management tools (e.g. decision-support tools) and know-how transfer from scientific studies to the end-users, i.e., the forestry practitioners, as well as inadequate monitoring still constitute considerable obstacles to SFM.

Forest laws in many tropical countries have been well elaborated, but the legal and political frameworks are often not stable enough to enforce laws and motivate people and companies for long-term engagement.

In particular, small landowners and communities have neither the financial resources nor access to state-of-the-art technologies in inventory, planning, and operations. Moreover, in practice, too many restrictions and bureaucratic obstacles have to be overcome. Education and training of the smallholders is difficult to organize and therefore non-sustainable practices may still prevail in many tropical forests.

The question of whether SFM is financially more attractive than alternative (land) uses is a crucial, long-term issue for the success of SFM. In a post-Kyoto regime, substantial financial compensation will hopefully be paid to forest owners (e.g. in the form of REDD), so that a significant amount of tropical forest will be preserved for future generations.