Obviously, as far as forests are concerned, the best management practice would be to leave them untouched. However, with the current demand for forest products, and with rapidly increasing human populations in tropical regions, this is an unlikely prospect for the majority of large tracts of forest. For most, some sort of management will be required to prevent their complete demolition. There are a wide variety of forest management practices, often with differing and even incompatible goals. Management for ecosystem and genetic resource protection as a primary goal will coexist uneasily with management for sustainable commercial production. As greenhouse gases in the atmosphere increase and carbon sequestration by forests becomes an important issue, and as populations swell in tropical countries, the tension between these goals will increase. Even when the goals are oriented toward conservation, there are different ways of approaching them. Improving the productivity of managed forests is essential, since increasing the yield of timber and other forest products in such forests is far preferable to removing more virgin forest.
a. Sustainable forestry – how it works: By far the most important management practice at present is “sustainable forestry,” often allied with “selective logging” practices. Sustainable forestry has been touted as a way to reconcile the demand for tropical woods with preservation of forests. By carefully removing only as many of the trees or other products as can be replaced relatively quickly and leaving others untouched, and, in addition, planting tree seedlings of desirable species, it is thought that forest ecosystems can be maintained so as to provide many crops of timber or other forest products. After an initial harvest, the forests would be left alone for an extended period of time, after which they could again be harvested for valuable products. In order for this system to be effective, there are several imperative preconditions: One, that the populations of organisms in the forest are able to produce a reproductive surplus; two, that there be adequate relatively undisturbed habitat; three, that soil fertility be maintained; and fourth, that erosion, runoff and road construction be kept to a minimum.
In some contexts, the term “sustainable forestry” is equivalent to “sustained-yield logging,” that is, a system in which the harvesting of timber occurs at a rate such that timber will continue to be produced at an equitable rate, or, as Vincent (1995) puts it, sustainability is to “…harvest forests to produce an even flow of timber over time.” These methods have been used for many years in European temperate forests, where trees are planted and harvested on regular schedules. This gives a sustained yield of timber, but may not be equivalent to “sustainability” of the forest per forest. Nor are these forests in any sense “natural” forests. In general, forestry in temperate countries operates to replace complex natural ecosystems with ecologically simplified forests managed strictly for maximum timber production. They are timber plantations, not true forests. Alternatively, the goal of sustainable forestry can be not just to provide a constant yield of timber, but to maintain the diversity of forests and to ensure that their ecological services remain intact. In this case, sustainable forestry means that timber is extracted in such a way that the forest can regenerate after logging into a complex ecosystem with most of its former components.
Logging in sustainable forestry may be selective, where only certain species or a limited number of individuals may be taken, or clearcut, when all of the trees in a selected area are removed. Then, in either case, the forest is left to regenerate. Management of regeneration ranges from allowing natural processes to occur unimpeded, or cleaning up the site (raking and burning the slash), or preparing the soil for growth of seedlings – either natural or planted. How successful these practices are in promoting forest regeneration depends on many factors such as the intensity of logging, the size of logged areas, the quality of the soil, and the distribution of logged areas within the forest. Proponents of clearcutting believe that it is more efficient, requires fewer roads per hectare, and leaves the logged areas easier to burn, when burning is used to stimulate regrowth. On the other hand, clearcutting of large areas exposes the soil to erosion, causes loss of biodiversity, and makes the cut-over land unreceptive to reforestation. Some of these effects can be minimized by reducing the size of the cut.
Primary forests in many areas are now reduced to patches surrounded by huge disturbed areas – scrub, agricultural land, pasture, and partially-logged forest. Recovery of forests under these circumstances is quite different from recovery from small gaps because of variability in the size of the cut patch, the number and distribution of species remaining (upon which their reproductive success depends), land-use history, and landscape heterogeneity. Forest regeneration may occur if the land has not been too severely degraded. Almost all of the forest in Singapore had been cleared by the early 1880’s. Now, more than 100 years later, some areas have regenerated quite well, although there are no dipterocarps or other large-seeded trees in the new forest, mainly because all of their seed dispersers are extinct on the island. Other, more degraded areas have regenerated much more slowly (Chazdon, 1998a). In Sarapiqui, Costa Rica, secondary forests have formed rapidly following deforestation. After 20 years, the species distribution of trees is similar to that of the original forest, although the trees are not yet as large. In this case, there is primary forest near the deforested area, and there are still many seed-dispersing birds and mammals present (Chazdon, 1998a).
b. Problems with sustainable forestry: Many tropical forest experts feel that since primary forests, along with their enormously complex life webs, have taken many hundreds of years to develop, it is probably preposterous to speak of “sustainable” logging. Any logging will damage these biological webs and degrade the forest. Rice, Gullison and Reid (1997), on the basis of research done in Chimanes Permanent Timber Production Forest in Bolivia, suggest that letting loggers take all of the valuable timber rapidly may make more sense, because after the most valuable species (mahogany, in this forest) is gone, the forest will not be of much interest to the logging companies. It may be objected that this will be true only until the market, starved of the most popular species, seeks alternatives in lesser-known species and timber companies return to remove these additional species from the forests. And in other parts of the world, such as Asia and Africa, more than one tree species is sought. Today, as pressures on forests are increasing, “single-species extraction” is becoming rarer as a logging technique. Also, much damage is done during the logging process itself (see below). Thus, it is questionable whether or not sustainable forestry is even an attainable goal.
i) Although only a few trees may be removed per hectare, many other trees may accrue ancillary damage during logging, particularly during mechanized logging. Many smaller trees and non-timber trees sustain damage or are killed when cut trees fall on them, or when bulldozers enter to retrieve cut trees. Selective logging in a diverse, primarily dipterocarp forest in the state of Pahang, Malaysia, resulted in damage to 51% of the trees, although only about 18 trees per hectare (3.3% of total trees) were taken out (Johns, 1991).
ii) Road construction causes erosion and runoff, damages vegetation other than trees, greatly compacts soil, and removes topsoil and seedlings. Logging roads are the most difficult areas to reforest.
iii) Log-loading areas and “skid trails” require clearing of substantial areas of forest.
iv) Climbing plants such as strangler figs and lianas are damaged, or more often, deliberately cut to reduce the probability of pulling down other trees. These plants are essential components of the forest, providing food and shelter for canopy-dwelling species and supporting larger trees.
v). From a practical standpoint, timber quotas are frequently ignored. In Chimanes logging companies basically “mined” the forest for the most valuable species, mahogany, and extracted all specimens of this species which it could locate (Rice, Gullison & Reid, 1997).
vi) The emphasis on certain valuable tree species endangers biodiversity, even if reforestation is permitted. For instance, at Chimanes, the effort to produce mahogany requires thinning of other species, so much so that the forest does not regenerate in a natural fashion and much biodiversity is lost. Too, since mahogany is a climax species and is shade-intolerant, great swaths of other species of trees are cut down to provide gaps where mahogany seedlings can be planted.
vii) Some studies indicate that many animal species are disturbed by even modest logging (Venezuelan antbirds, for instance).
viii) Logging roads provide an ingress for farmers, miners, poachers, and commercial hunters to the forest. They and loggers usually subsist on hunting, which decimates local populations of primates and other large mammals.
ix) Sustainable forestry may not be practiced because it is more profitable to cut down all of the valuable trees quickly (mahogany, for example) than to invest in a slow-growing capital (i.e., mahogany seedlings) and wait for them to mature. There is no economic incentive to practice sustainable management, as unrestricted logging is two to five times more profitable than sustainable forestry.
x) Governments are often unhelpful. They provide little or no money or personnel to monitor timber companies (which are often politically connected and powerful) and, on the contrary, often prefer a short-term benefit in foreign trade to long-term sustainability of their resources.
xi) The effects on plants and animals of sustainable forestry are not well known. On the negative side, many of the pioneer trees which will occupy the gaps created in the forest are not species which can be used for food by animals, and the full diversity of food types will not return until the climax forest is attained (more than 80 years for dipterocarp forests). A study in French Guiana indicated that, for 10 years after selective logging had removed three or fewer trees per hectare from forest plots, biodiversity and population size of plants and animals were reduced by 25% in comparison with unlogged areas (Alper, 1993). On the other hand, there are suggestions that the remaining trees and plants may produce more leaves and fruits, which might offset the loss of other resources. Downed trees themselves are important sources of food and shelter.
There is much we do not know about the potentialities of sustained forestry. (For an excellent discussion of sustainable forestry and an extensive bibliography, see Hartshorn, 1995.)
c. Improving forest management: Less-destructive methods of forest management and logging can certainly be instituted by improving forest management before, during and after resource extraction. What procedures need to be undertaken by forest managers to ensure forest regeneration and preservation?
i) Preservation of forest reproduction: There is little information on the reproductive patterns of valuable nondomesticated tropical species. Therefore, many individual trees may be harvested prior to maturity. If near-adult organisms are taken before they produce seeds, that species may become endangered. The timing of harvesting is also important, as fruiting and setting seed are seasonal for many species. Harvesting should be done after the reproductive season for that species is over. For example, in the Amazon, mahogany is usually cut at the end of the dry season, although it reproduces early in the rainy season which follows. This is a most destructive practice. Also, any species which are keystone species or extremely important in the ecosystem should not be harvested frequently, if at all. For instance, the fruits of figs and palms are essential foods for many animals. Just as critical is the capacity of a species for reproduction. Some species can regenerate by sprouting from stumps and thereby survive cutting. Other species, such as bamboo and some palms, reproduce only after many sterile years and then die, thus cutting them prior to reproduction is fatal for that population.
ii) Allowing natural regeneration: Natural regeneration is required for sustainable forestry. Regeneration in a natural way requires some gaps in the forest, although these cannot be too extensive. This mimics the natural course of events, where the death of trees or wind or fire open gaps in the canopy. It is also necessary to know something of the requirements of seeds for germination and of seedlings for development. In the tropics seedlings of any particular species are often at a low density, and seeds may have only a short period of viability. Many seeds need to pass through an animal gut or to be exposed to heat or moisture in order to germinate. Then, too, many species fruit only sporadically. Thus there are many requirements for adequate reproduction, which vary according to species. The low density of individuals of any one species in tropical forests and their frequently poor capacity for reproduction is a problem in sustainable forestry. Seedlings of the desired species may be planted, but it is often not economically viable to do so, as a great deal of forest may have to be opened for light (as in the case of mahogany), or extensive and labor-intensive weeding may need to be done.
iii) Maintaining ecosystem functions and biodiversity: Forestry is generally thought to be incompatible with the preservation of ecosystem function and natural biodiversity. Natural forest areas need to be maintained for this purpose, a need often ignored by farmers, logging companies, and government planners. Careful management is required to prevent land degradation. Where logging is done so as to minimize erosion and soil compaction, nutrient losses can be replaced during natural regeneration. The use of heavy equipment must be used very sparingly, if at all, and logging roads must be carefully designed to take into account soil type and land topography. Especially, the harvesting cycle must be lengthy enough to allow for complete regeneration.
Immediately after logging, biodiversity drops precipitously. It can rebound to some extent, although the species returning may not be the same as in the original forest. Forest exploitation may be diversified to minimize damage to these areas. For example, sensitive areas should be preserved untouched, and areas which are to be logged can be dispersed and kept as restricted as possible. “Cluster-cutting” from nuclei, or “strip-cutting” (clear-cutting narrow strips) may permit more natural regeneration than traditional cutting. Some areas may be managed intensively for production, others modestly for conservation and ecosystem preservation. If logged areas are converted to agricultural systems, much biodiversity is lost forever, although some may be maintained if many native species are planted. Agroforestry may be useful, although even when local plants are used, biodiversity is much reduced from that in primary forest areas.
iv) Using less-destructive and innovative means to provide timber:
a. Increasing the productivity of popular timber species: The slow growth rate of many large hardwood tree species is an impediment to sustainable forestry. Species which colonize gaps (pioneer species) and which grow rapidly can reach the canopy within 10 to 20 years and could be utilized for sustainable timber production. Plantations of such species could provide a large percentage of needed timber in the foreseeable future. Species which provide high yields can also be planted. In the Philippines, scientists have developed giant species of a timber tree, Leucaena, which produce three times the yield of the natural species (Spears, 1988). If plantations of these giant trees were to be established, cutting of virgin forests could be reduced or eliminated.
b. Utilize less-known tree species for timber: Typically, only a few well-known (and hence valuable) species are utilized by the timber industry. However, many more species could be exploited to increase the yield per hectare of logged forest land. For example, there are 200 potential timber species in Asian rainforests, but only a few species are harvested. If more of these lesser-known and little-utilized species were marketed, rather than being discarded and destroyed, less forest would need to be cut to provide timber resources. In Malaysia, between 1977 and 1981, utilization of lesser-known species was doubled and these species comprised 27% of the log intake of plywood and veneer mills (Spears, 1988).
c. Instituting less-destructive logging activity, using the following methods:
i) Make a forest inventory and map prior to logging. This reduces waste because logging activities can be planned and felled trees located.
ii) Plan the movements of machinery. According to Uhl, et al., (1997), machinery has an impact on approximately 25% of the land area during logging, but careful planning can minimize the area in which machinery moves.
iii) Cut vines two years prior to logging so that when trees are cut, other trees connected to them by vines are not pulled down.
iv) Train loggers in proper logging techniques. One can reduce waste by a factor of three in this way, since improper techniques are a major cause of tree wastage.
v) Reduce machine operating time by planning and preflagging skid trails.
vi) Girdle undesirable trees to provide space for commercial species.
vii) Limit the size of cuts so that natural reforestation can occur and so that effects on biodiversity are minimized.
viii) Exclude clear-cutting of forests and their conversion to pastures and other nonsustainable agricultural uses.
ix) Monitor and assess the condition of the forest in terms of canopy, seedling availability, and biodiversity.
By utilizing these procedures one might reduce harvesting cycles from 70-100 years to 30-40 years. The increase in production from already-logged areas would reduce the need to open up new areas to logging. Healthy populations of commercial species must, however, be maintained in the logged areas.
v) Legal action: Among the actions which can be taken by the forestry sector to conserve rainforests are the following:
a. Adopt and enforce simplified, effective, enforceable forestry codes. Current regulations are conflicting, confusing, and worst of all, seldom adhered to. Limits might be set on the number of trees extracted, cutting cycles specified, and fire zones established to minimize the danger of fires.
b. Regulate permissible areas for logging. For example, one should exclude areas with high degrees of endemism and biodiversity, as well as parks and areas reserved for indigenous peoples. Logging is to be allowed only in designated areas.
c. Reduce levels of timber harvesting to a sustainable level.
d. Establish an “ecology tax,” where the costs of forest management are passed on to consumers.
e. Mandate forest management by law. Conservation and biodiversity preservation programs should be incorporated into forest management programs. Logging, where continued, should be low-impact and should preserve forest diversity.
These measures can only be effective where there is strict enforcement of regulations.
vi) Approaches based on traditional agroforestry and shifting agriculture: Traditional agroforestry utilizes few materials external to the forest itself and relies on natural replenishment of soils by decomposition. In agroforestry, crops (food for man and animal, medicines, construction materials) are typically raised under the forest canopy. Small gaps are opened in the forest by cutting some large trees, burning the area, and planting several sequences of crops until the soil loses fertility. Frequently trees such as rubber and various fruits are planted. After this, the area is abandoned and left to regenerate for a number of years. This type of agriculture has been practiced for many centuries, so that probably much tropical forest which appears to be virgin forest is actually secondary forest. Such forests often have higher concentrations of fruit, rubber and other trees than the primary, original forest, and can continue to provide food and income for local inhabitants even during the fallow period. This type of agriculture can be successful only when the human population is small and no other use is being made of the forest.
d. Why is sustainable forestry relatively rarely attempted in tropical areas, even if the timber companies are in agreement with its principles?
i) Unrealistic expectations of yield: The first yields will be at non-sustainable levels (large), as they are taken from pristine forest. Subsequent harvest yields will be lower, as they are taken from a population of growing trees, not mature ones. Unfortunately, the initial (large) harvest leads to unrealistic expectations of yield from the regenerating forest. Timber companies have developed infrastructures to harvest a large yield, and when this does not materialize, they may harvest unsustainably to recoup their investment. This type of exploitation will reduce future yields even more, however.
ii) There is often little comprehension in the harvesting industry that natural populations will fluctuate over time, even without any harvesting. This leads them to attempt a constant harvest rate, regardless of population dynamics.
iii) The tendency of people using rainforest products is to overexploit them; this is particularly true of large companies. Successful sustainable forestry is usually accomplished by small-scale, private or community institutions.
e. What actually happens – Case Study: Sabah, a Malaysian state in north Borneo, has forests with a high density of commercially-useful tree species, and logging has been extremely intensive. In logging concessions, all commercial timber of a useful diameter (“selective logging”) is cut, resulting in a very high extraction rate (8 – 14 trees per hectare). What remains after extraction is a mosaic of areas – undisturbed forest (about 20%); disturbed forest where there is some ancillary tree damage and some disruption to the canopy (20%); areas containing debris, where both canopy and the understory are disturbed (30%); skid trails, which are bulldozed through the forest to provide entry for equipment and an exit route for timber; and log landing areas where vegetation, litter and topsoil have been removed (30%). After logging, the soil is left compacted, mainly because of the heavy machinery used. The effects of this type of logging operation are: (Data below are from Nussbaum, Anderson, and Spencer, 1995.)
i) An increase in erosion rates and sedimentation of waterways. Erosion is low in undisturbed forest, but increases considerably after logging. After one year, the increment in erosion in logged areas was approximately 3½ times that of unlogged areas, because most of the exposed topsoil had been washed away. Suspended sediment in waters near the logged areas was eighteen times greater than in unlogged areas.
ii) An increase in soil compaction: Soil compaction is so great where heavy machinery has passed that researchers could not measure any infiltration into soil on a log landing after two hours of rain. In undisturbed areas, the infiltration of rainfall was measured as 154 mm/hour.
iii) Alterations in vegetation: Vegetation was damaged, canopy cover was decreased and, in large gaps, the growth of vines, climbing bamboos and other sun-loving species overwhelmed the growth of dipterocarp (hardwood) seedlings which are light-loving but do not grow rapidly. Where less than 50% of the canopy remained, three-quarters of planted dipterocarp seedlings were overgrown by vines, as compared to about one-tenth in undisturbed areas.
iv) A reduction in biodiversity in comparison with undisturbed areas:
f. “New forestry”: Still, some projects, based on “new forestry,” give hope for the future. According to the principles of “new forestry,” forests should be managed in such a way as to maintain the forest ecosystems, rather than to follow the traditional idea of forests as a source of timber only. Under these principles, forests would no longer be managed to maximize wood production by homogenizing ecosystems. In new forestry, the maintenance of biodiversity is essential, including ground level and underground biodiversity. Even the detritus on the forest floor – dead vegetation and trees – must be maintained. This concept has yet to percolate to tropical forest management, for the most part, although there have been a few attempts.
i) The Programme for Belize, under the auspices of The Nature Conservancy and the Massachusetts Audubon Society, in the Rio Bravo Conservation and Management Area, is an example of new forestry principles. Half of the land is set aside as a nature reserve. In the other half, some cutting is permitted, but all trees more than 12 inches in diameter are mapped. Cutting here is done very carefully to ensure that trees fall and log removal is done in such a way as to do the least damage. PfB then sells the products and the profits are used to maintain the reserve. PfB also works with local inhabitants, hiring them as foresters and rangers, and helping villagers begin small businesses such as honey and fruit production (Clancy, 1998).
ii) Portico S.A. (Brazil) is a company which manages its own forests in an enlightened manner. It has incorporated local farms into its management policy and provided employment for local people. It has a management plan for each of its properties, based on inventories of tree species, their sizes and distribution, and regeneration status. It uses less-destructive logging methods (non-mechanical) and trains its staff how to minimize damage to remaining forest. Moreover, it is involved in research and monitoring and conservation is a component in its policies. No hunting is allowed on company land and its properties are patrolled for compliance. Although these policies increase the raw material price, the additional costs are absorbed by the vertical integration of the company.
iii) In Peru, the Yanesha Forestry Coop (a joint venture of USAID and the Peruvian government) has a community-based project in the central Selva area, which is unsuitable for agriculture and livestock raising. The Cooperative is a group of local people who own and process forest resources and cut timber so as to maintain diversity. Clear-cutting is done in narrow strips to leave large forest areas intact; this attempts to mimic gap formation and to stimulate natural forest regeneration. Trees are to be cut on a 30 to 40-year rotation cycle.
(Information on Portico S.A. and Yanesha from Hartshorn, ; on Yanesha, in Postel and Ryan, ).
However, new forestry – or any kind of forestry – is NOT a substitute for forest preservation. Unfortunately, we know little about how to manage forests in a sustainable manner. Any type of management must realize that forests in the future cannot continue to produce timber at the current rate. Even with the use of “new forestry” and sustainable forestry, reductions in the volume of timber extraction will be required. This, of course, is a substantial economic and political issue.
g. Plantation forestry: Many large international timber companies have established tree plantations in the tropics. Trees in plantations tend to be cut while still young, and are therefore less desirable than trees from primary forests. Only 12% of tropical plantations are stocked with hardwood species which provide wood comparable to wood from natural forests (Postel and Ryan, 1991). Nevertheless, these plantations are often highly productive, and can reduce the need to log old-growth forests. Often the trees planted are hybrids and/or nonnative species. The most popular species are Pinus (pines), Eucalyptus, and Acacia. These species, since they are not in their native areas, are less subject to disease than otherwise, but they are nevertheless attacked by a variety of pathogens, both native and those introduced with them. These disease agents include root, leaf, wood and seed pathogens, which find abundant hosts in these plantations. A rust, Puccinia psidii, native to the Neotropics, has begun to infest stands of Eucalyptus (an Australian tree) on tree plantations in South America (Wingfield, et al., 2001). This and similar infestations reduce the productivity of the plantations and their role in the global timber trade. As yet the infestations have been limited, but new diseases are continually appearing and can be expected to have significant effects on timber production in managed plantations. In addition, species introduced to areas outside their normal range can “escape” and become pests (“weeds”).
Many of these problems can be overcome. In the Subri Forest Reserve in Ghana, much of the vegetation and small trees is retained during logging and the establishment of plantations. This method leaves mycorrhizal associations at least partially intact and reduces erosion. Some natural forest is left to minimize the transmission of pathogens (Postel and Ryan, 1991). Unfortunately, most plantations are not so well managed. According to these authors, mixtures of fast- and slow-growing species and fibrous and hardwood species would give a competitive yield of timber and pulp. They estimate that such plantations, on only 5% of the land already cleared of tropical rainforests, could provide twice as much wood as the current harvest.