Convention on biological diversity

III.Market and economic failures

Under-valuation of forest biological diversity, goods and services

IV.Policy failures

Ill-defined or regulatory mechanisms and lack of law enforcement.

Perverse incentives and subsidies and ill-defined development programmes

Furthermore, direct or indirect subsidies are given to economic forest operations that can damage biodiversity, such as the drainage of forests and the logging of old growth forests (Sizer and Plouvier, 2000). The most common and important type of subsidy in the forest sector is that implicit in the low forest charges paid by timber concessionaires. Although justified on grounds of promoting local development and employment, they can sometimes lead to a “boom-and-bust” situation with consequent excessive and wasteful forest degradation (Contreras-Hermosilla, 2000).

Lack of Environmental Impact Assessments or Strategic Environmental Assessments

4. 
   
   
5. 
   TRENDS IN FOREST BIOLOGICAL DIVERSITY
   

A. Introduction

B. Forest cover

The rate of forest decline, particularly in the past two decades, is alarming. Although there are indications that the rate of deforestation in developing countries is marginally decreasing, this trend probably does not suggest any greater emphasis towards conservation. Between 1990-1995, the annual estimated loss of forest cover (deforestation plus exotic plantation) of 13.7 million ha per year was slightly down from the previous decade (1980-1990) when annual estimated loss of forest cover was 15.5 million ha per year. However, the average rate reported for the 1990s was more than 16 million ha/year (FAO, 2001a), of which almost 95% was in the tropics, indicating that the rate has increased in the past five years. The rate of deforestation varies considerably among regions: for example rapid clearing of lowland forests in Sumatra is likely to lead to almost complete removal of primary forests within the next 5 years Jepson et al. 2001). Between 1990 and 2000, the area of global forests decreased by nearly 94 million ha, (-0.78% annually in Africa, -0.07% in Asia, -0.18% in Oceania, +0.08% in Europe, -0.12% in North and Central America and –0.41% in South America (FAO, 2001b). The overall picture is one in which deforestation is proceeding at excessively high levels that will continue to result in major losses of FBD.

C. Forest quality

The area of forest plantations increased by an average of 3.1 million ha per year during the 1990s, with half of this increase (1.6 million ha) resulting from afforestation, whereas the other half (1.5 million ha) resulted from conversion of natural forest (FAO, 2001a). Global planted forest area has been estimated to be almost 187 million ha (FAO, 2000). During 1990-2000, Asia contained 62 per cent of total plantation area, with Europe 17 per cent and North and Central America at 9 per cent. The quality of plantation forests in terms of maintaining biodiversity is often much reduced compared to primary forests, especially in the tropics where natural forests are converted to rapidly growing commercial trees, which are often exotic species (e.g. LaMonthe 1980, Estades and Temple 1999).

According to the TBFRA report (UN/ECE and FAO, 2000), 55% of forests in the temperate and boreal regions combined was recognized as largely primary (natural in the report and undisturbed by man), 41% as secondary (termed semi-natural in that report) and 4% as plantations. Figures for other wooded lands, such as tundra woodland, shrublands and savannahs were 39%, and 61%, primary and secondary, respectively. In both categories the high percentage values of natural areas were due to the vast boreal areas of the Russian Federation and Canada. However, the high values are due to the ways in which these two countries distinguish between natural and disturbed areas. If relative naturalness is analysed outside the Russian Federation and Canada, the figure for primary forests “undisturbed by man” drops to just 7% of the total boreal and temperate forest area.

Bryant et al. (1997) reported that 48% of the world’s remaining primary forests are boreal, 44% tropical, and only 3% are temperate; (5% contain both temperate and either boreal or tropical forest). Due to their favourable climate, fertile soils and good access, temperate forests were the first to be cleared by humans and the remaining primary stands represent areas that should be fully protected.

In tropical regions, a considerable portion of existing forests can still be classified as primary, although there are great regional differences (Bryant et al., 1997). In Asia and Africa, though roughly a third of the original forest cover remains, less than 10% of this original cover still qualifies as primary forest. Bryant et al. (1997) also estimated that outside of boreal forests, about 75 percent of the world’s primary forest is threatened. Matthews et al. (2000) analysed the world’s forests by using three forms of human activities that are known to be good indicators of environmental change: the spread of ‘transition zones’ (agriculture practiced at the margin of intact forest), road construction and the use of fire to clear forests. Their results were similar to those of the earlier studies of harvested forests, showing increased rates of harvest in both in primary forests and in secondary forests. There is a slow but steady increase in the amount of harvesting operations occurring in secondary forests (FAO 1995). This suggests large-scale forest quality changes in all kinds of forests, and consequently fewer forest stands regenerating naturally after cutting activities and other human caused disturbances, as well as fewer stands attaining the oldest age classes.

Use of, and change in, forest resources is a serious concern to maintaining biological diversity and proper functioning of forest ecosystems. Human disturbance of forest habitats through logging and road access can affect species diversity through habitat loss, fragmentation effects and hunting, unless a sound sustainable use programme is in place. Habitat loss is one of the three most important causes of species extinctions locally and globally in forest habitats (WCMC, 1992). There is a strong relationship between the extent of deforestation and the level of species extinctions and endangerment (Pimm et al. 1995). Skole and Tucker (1993) suggested severe deforestation in several areas of the world over the next 20 years, such as in the Amazon Basin where more than 40% of the forest will be cleared for development. This rate of deforestation will clearly have far-reaching effects on biological diversity. Even in supposedly well-managed forests, where although extinctions are few, most evidence to date suggests that there is a lack of convergence between original animal and plant communities and those in the regenerating forests (Carleton and MacLellan, 1994; Thompson et al., 1999; Lomolino and Perault, 2000).

Riitters et al. (2000) studied global-scale patterns of forest fragmentation based on 1 km resolution land-cover maps. When anthropogenic causes of fragmentation are considered, forests are more likely to be disturbed where the climate is hospitable, soil is productive and access is easy. Boreal countries still contain a high percentage of interior forest. However, in temperate Europe and eastern North America where the conditions are more hospitable and accessible, humans have converted large areas to non-forest uses such as agriculture. Tropical rain forests remained relatively intact until access was provided by governments or industry. In the Rondonia region of Brazil, for example, the pattern of residual forest is directly related to the road pattern (Dale and Pearson, 1997). In the Amazon basin, there are corridors of fragmented forest that follow major rivers and other access routes into larger regions of interior forests. These results clearly indicate the crucial role of road networks in both deforestation and forest quality changes.

In temperate and boreal forests, advanced silvicultural practices have often caused a general homogenization of forest stands and larger forest landscapes. In particular, the size of forest patches caused by logging is reduced in comparison to patches created by natural disturbance regimes (Perera and Baldwin, 2000). In part change to forest structure and species composition in these biomes has resulted from selective logging of tree species, thinning activities, removal of dead and decaying wood and from managing the forest stands systematically, usually in a short rotation time (Maser 1990).

D. Loss of species and genetic diversity

The 2000 IUCN Red List is an inventory of the global endangered status of threatened plants and animal. It uses a set of criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are intended to be relevant to all species and all regions of the world. For the first time, the 2000 Red List combines animals and plants into a single list containing assessments of more than 18,000 species (11,000 of which are threatened).

The World Conservation Monitoring Centre/UNEP and IUCN Species Survival Commission have developed a database of rare and endangered tree. Information on individual tree species is recorded in the Tree Conservation Database and includes the IUCN red list category, information on distribution, uses, ecology, threats and conservation measures. Summary information on individual species is published in The World List of Threatened Trees (Oldfield et al. 1998). The species presently included in both publications tend to be in certain tree families and genera (e.g., conifers, palms and dipterocarps) and on certain countries and regions, e.g. Africa, reflecting the particular interests and knowledge of the contributors. Together with information in appendices from Japan, Australia and elsewhere, the total number of globally threatened²⁶ tree species was reported to be 8,753, equating to about 9% of the world’s estimated 100,000 tree species²⁷. The loss of any tree genus or species will be accompanied by the loss of a variable and unknown number of obligate-associated species (including parasites, predators, pollinators and microsymbionts) and understory plant and animal species. In the tropics, the number of such associated species may be conservatively estimated²⁸ to be of the order of 10 to 100 per tree species.

A few generalities relating threatened species and forests should be noted:

(a) Tropical forests are extraordinarily rich in biodiversity. Threats to tropical forests therefore tend to result in very large numbers of species becoming threatened. This is especially the case if these threats take place in one of the forest areas where there are particularly high concentrations of endemic species (sometimes referred to as ‘hotspots’).

(b) Certain forest species are climax species. Even relatively minor disturbances can result in some species loss. There are many species that depend, for instance, on standing dead trees or on dead wood lying on the forest floor, and both of these 'habitats' tend to be absent in highly managed forests.

(c) There is good evidence that, at least in certain parts of the world, extinctions of forest species take place if the habitat becomes fragmented and mixed with non-forest areas (Andren 1994). Such extinctions can occur even if the forest in the surviving fragments remains undisturbed. This phenomenon has been demonstrated in particular in the Americas. [reference needed].

(d) Economically valuable forest species are currently being subjected to particularly high harvest levels in several parts of the world (UNEP 1995). Such harvests include the well-publicised trade in bush meat, but also harvest for medicinal purposes, valuable timber and a host of other non-timber forest products. Use of forest species has generally been very difficult to manage sustainably, partly because of the inherent lack of controls in many major forest areas, a lack of knowledge of populations and partly because of the slow reproductive rates of many forest species, which means that even low levels of removal can be detrimental.

Very few high priority economically important forest tree species are under immediate threat at the species level, but in all regions many species are threatened at the population level. The 11^th Session of the FAO Panel of Experts on Forest Gene Resources lists over 400 tree species as being global, regional or national priorities and points out those species in need of in situ conservation (FAO, 2000c). A number of regional workshops have been held which document information on the state of forest genetic resources, including, although not focussing on, threatened species and populations in the Boreal Zone (Anon, 1996b), North America (Rogers and Ledig, 1996), Europe (Turok et al., 1998), Sub-Saharan Africa (Sigaud et al., 1998), Eastern and Southern Africa (Sigaud and Luhanga, 2000) and the South Pacific (Pouru, 2000c). For example, a report on the state of forest genetic resources in the Sahelian and North Sudan zone of Africa shows that many important tree species and populations are subject to strong pressures and are at high risk at population level; the report identifies ten species in need of in situ genetic conservation measures.

In temperate zones, some tree species are threatened at the population level. This applies also to well-known and economically important tree species such as Pinus radiata that is threatened throughout its native range. In this case, the three mainland California populations are threatened by pitch canker disease and urbanization, while on Guadalupe Island (Mexico) the species is no longer regenerating due to browsing by goats (Spencer et al., 1998).

In all areas where deforestation has been extensive, it is likely that genetically distinctive, unique populations of plant and animal species have disappeared. This process of extinction of local populations will continue over the next few decades both directly through habitat loss and as a result of the time lag associated with the process of “relaxation” in which the original number of species in the fragmented area eventually falls back to a new, lower number (Diamond, 1972). Bird species in fragmented tropical forest communities will have declined about 50% of the way toward their future equilibrium after 25-100 years in large fragments of around 1000 ha (Brooks et al., 1999). Many bird species have been affected in the heavily cleared woodland communities of eastern Australia and are now declining at an alarming rate, with 20% of Australian bird species now considered threatened. [reference needed].

The most pervasive threat to birds, mammals and plants is habitat loss and degradation, affecting 89% of all threatened bird species, 83% of threatened mammals and 91% of threatened plants [WCMC 1992].The primary causes of habitat loss and degradation are agricultural activities including land clearing, extractive activities and development of infrastructure and settlements. Direct exploitation is also a principal danger, affecting 37% percent of threatened birds, 34% of threatened mammals and 8% of threatened plants (WCMC, 1999). Some large species, like great apes, faced a serious combined threat to their survivel, both by predation by humans for bush meat and by the habitat loss through logging and land use changes, see Box 9. Alien invasive species are a third major source of threat, affecting 30% of threatened birds, 15% of threatened plants and 10% of threatened mammals (Hilton-Taylor, 2000). For tree species in particular, the most frequently recorded threats consist of: felling, agriculture, expansion of settlement, grazing, burning, invasive species, forest management, local use, mining exploration and tourism/leisure (Oldfield et al., 1998).

Threats can be recorded at species level (the whole species is endangered) or at population level (only some populations of the species are threatened). Threats at population level can severely reduce genetic diversity and the potential for breeding and domestication, such as in the case of wild fruit trees [reference needed?]. A pervasive threat to genetically diversified local tree populations, which may have developed valuable attributes, lies in the introduction of non-local forest germplasm for forest plantations or rehabilitation. This could lead to hybridization of local and introduced trees and to a dramatic dilution of native, locally-adapted gene pools in subsequent generations (Ouedraogo and Boffa 1999).