Chapter 5. Biological diversity

ABSTRACT

Biological diversity denotes the variety of life forms, the ecological roles they perform and the genetic diversity they contain (FAO 1989). While recognizing the complexity of the issue, the Expert Consultation on Global Forest Resources Assessment 2000 ("Kotka III") recommended that FRA 2000 address key indicators that might contribute towards a better understanding of the status and trends in forest biological diversity, including information on forests by ecological zones; protection status; naturalness; and fragmentation. In other chapters and in the global tables, this report provides information related to these indicators. Two studies carried out within the framework of FRA 2000 are summarized in the present chapter. These address the number of forest-occurring ferns, palms, trees, amphibia, reptiles, birds and mammals by country; and the spatial attributes of forests that define one aspect of "naturalness", applicable at the global level. Conceptual difficulties related to the assessment of biological diversity in forests at the global level are also addressed.

INTRODUCTION

It is generally accepted that the conservation of forest biological diversity, at the levels of ecosystems, landscapes, species, populations, individuals and genes, is essential to sustain the health and vitality of forest ecosystems, thereby safeguarding their productive, protective, social and environmental functions.

The greatest threat to forests and their diversity is conversion to other land uses. Increasing pressure from human populations and aspirations for higher standards of living, without due concern to the sustainability of the resources underpinning such developments, heighten these concerns. While some land use changes are inevitable, it is important that such changes be planned and managed to address complementary goals. Concerns for biological and genetic conservation should be major components of land use planning and forest management strategies (Soulé and Sanjayan 1998; Wilcox 1990; FAO 1995; FAO/IPGRI/DFSC 2001; FAO 2001).

Biological diversity is intensively discussed at policy levels and within the global scientific community, and it is the focus of attention of many international and national non-governmental organizations. A number of dedicated journals directly address biological diversity and related issues. At the international level, many organizations and agencies address biological diversity in their programmes (FAO 2001c). Forest biological diversity is a concern of the Collaborative Partnership on Forests (CPF) chaired by FAO. The Secretariat of the Convention on Biological Diversity (CBD) plays a lead role within the CPF on this issue.

Guidance was sought from the FAO Expert Consultation on Global Forest Resources Assessment 2000 (Kotka III) regarding the extent to which FRA 2000 might address this important issue (Finnish Forest Research Institute, 1996). The Kotka III report included the following recommendation on biological diversity:

The meeting recognized the conceptual and practical difficulties of directly measuring biological diversity, but noted that considerable progress in understanding the situation and trends for biological diversity in the world's forests could be made by including in the global framework questions on the following:

• naturalness (breakdown into natural forest, semi-natural forest and plantations);
• protection status (using IUCN categories to improve comparability);
• fragmentation;
• better information on forests by ecological zone.

Extensive reporting on these indicators, including protected areas, is provided in other chapters of this report. In addition, FRA 2000 carried out two studies on specific aspects of forest biological diversity. The results of these studies are summarized in this chapter. This chapter also discusses some of the conceptual and practical difficulties related to the assessment of forest biological diversity at the global level.

For further discussion of the status of efforts to assess forest biological diversity at the global level, refer to "Assessments of forest-based biological diversity" in the State of the World's Forests 1999 (FAO 1999).

ASSESSING FOREST BIOLOGICAL DIVERSITY

The goal of conserving biological diversity is to ensure that variability and variation will continue to be present and can dynamically develop and evolve both through natural processes and through the direct or indirect intervention or influence of humans (Eriksson et al. 1993; FAO 1989; FAO 2001c). The values derived from biological diversity are associated with different scales. These include ecosystems, landscapes, species, populations, individuals and genes. Varying and complex interactions exist between all of these levels (see Namkoong 1986; FAO 2000; Sigaud et al. 2000). In implementing a conservation strategy, it is important to specify which level of diversity is discussed and to identify the ultimate aim of the strategy (Eriksson et al. 1993; Palmberg-Lerche 1999; FAO/IPGRI/DFSC 2001).

Because biological diversity encompasses the complexity of all life forms, its assessment and monitoring are only possible for specific aspects or particular, defined goals. There is no single, objective measure of biological diversity, only complementary measures appropriate for specified and, by necessity, restricted purposes (Norton 1994; Williams 1999). The use of "indicator species" as a surrogate in biological diversity assessment is a common approach.

A number of major challenges must be faced in designing an assessment of global forest biological diversity. These are not unique to biological diversity, but are general inventory problems for variables in which target parameters are complex and highly variable.

First, the complexity and variation of forest biological diversity at the global level must be expressed in a simplified, uniform and easily understood set of variables that represent the major values of forest biological diversity. Such a set of variables must, by necessity, be based on generalizations that use indirect (surrogate) measures, typically in the form of indicators which are based on the general (qualitative) condition of the forest and the likely development following management events or natural developments (Thuresson et al. 1999).

Second, the inherently local nature of variations in biological diversity requires that data be inventoried on a sample plot basis and then generalized into broader spatial representations for reporting purposes. World maps indicating diversity at ecosystem or species levels can only indicate spatial variations at large scales, perhaps 10 km and larger. Summarized tables with national-level statistics on such variables will be much less detailed. Even if a good set of indicators is identified, part of the meaning may be lost when data are interpreted as an average over larger areas. This problem can, in theory, be at least partly remedied by reporting on local variations of specific indicators rather than averages, but this leads to other problems: assessing local variations is complex and very costly, and the results become more abstract, difficult to comprehend and difficult to incorporate in policy processes.

RESULTS OF FRA 2000 STUDIES

Given the above difficulties and severe data limitations, two studies were implemented within the framework FRA 2000 by the United Nations Environment Programme (UNEP) and the World Conservation Monitoring Centre (WCMC), (FAO 2001a; FAO 2001b). The first study reviewed and documented the number of forest-occurring species by country, and the proportion of these that were considered to be endangered according to the classification and definition of IUCN (see below). The second study addressed indicators of the spatial attributes and integrity of forests that might be applied at the global level and that define one aspect of "naturalness".

Study on endangered forest species

A desk study of endangered forest-living species was made to provide a generalized estimate of the national importance of forests as habitats for biological diversity, at the ecosystem and species levels (FAO 2001a). It was recognized from the outset that obtaining accurate data would be difficult; therefore specific groups of species were selected for review based on the anticipated availability of data.

The study was principally designed to make use of existing data from the databases at UNEP-WCMC, which supported a number of published documents, including the IUCN Red List of Threatened Animals (IUCN 1996), the IUCN Red List of Threatened Plants (IUCN 1997) and the World List of Threatened Trees (IUCN 2000). The categories used and criteria for establishing endangered status for species are fully documented in the source publications. This information is also available on the Internet (www.unep-wcmc.org).

Table 5-1. Data availability by species group

Group	All species occurring in country				Forest-occurring species
	All species		Endemic species		All species		Endemic species
	Total1/	Endangered1/	Total	Endangered1/	Total	Endangered	Total	Endangered1/
Ferns	Good	Good	Limited	Good	Good	Good	Limited	Good
Palms	Good	Good	Good	Good	Good	Good	Good	Good
Trees	No data	Good2/	Limited	Good	No data	Good2/	Limited	Good
Amphibia	Good	Good	Partial	Good	No data	No data	No data	Good
Reptiles	Good	Good	Partial	Good	No data	No data	No data	Good
Birds	Good	Good	Partial	Good	No data	No data	No data	Good
Mammals	Good	Good	Partial	Good	No data	No data	No data	Good

¹⁾ Column included in presentation of global statistics (Appendix 3, Table 13).
²⁾ For most countries.

Total number of species by country. In general, estimates of number of species by taxonomic group, by country, were available in the literature. To a large extent this information was also already recorded in the UNEP-WCMC species database. This database was updated as part of the FRA 2000 study. An exception to overall availability of data was information related to the category "trees", for which data on country (and global) totals were not available. "Trees" is not a readily definable group and data will have to be gathered on a species-by-species (or genus by genus) basis, in the absence of an authoritative, global world list of trees. Currently the only possibility is to estimate figures based on national floras, where these exist. Such work was beyond the scope of the FRA 2000 study.

Total of forest-occurring species by country. Reliable data were only available for two relatively small groups, palms and ferns. Figures for all forest-occurring species in these groups by country were not available from the literature nor in the UNEP-WCMC species databases.

Endemic species by country. Some information on endemic animal species, i.e. species occurring in one single country, was available in the UNEP-WCMC database of endemic animal species. Complementary information from country-based reports was added, where available. Palms, once again, proved to be an exception, with good data available.

Endangered species per country, aggregated at global level. Good data were available for all categories, based on the UNEP-WCMC threatened species databases.

Forest-occurring endangered species per country, aggregated at global level. Good data were available for the category "plants". Data were not available for animal species. As reported for the above categories, the task of identifying the occurrence of threatened animal species in forests, on a species-by-species basis, was beyond the scope of the present study.

Endangered endemic species by country. Data for this subset were available in the UNEP-WCMC databases.

Endangered forest-occurring endemic species by country. In this subset, all threatened endemic species that occurred in one single country, in forest ecosystems, were identified.

The results, by country, are shown in (Appendix 3, Table 13) Information is given in those columns in which reliable data were available for the above-mentioned groups of species. Figure 5-1 displays the total number of endangered, country endemic and forest-occurring species against the forest area change for countries with more than 1 million hectares of forest.

The FRA 2000 questionnaire sent by UNECE/FAO to industrialized temperate and boreal zone countries included a request for information on endangered forest-occurring species. The outcome is not directly comparable with the findings of the global study reported above, and the results are therefore not included in this chapter. However, this complementary information can be found in UNECE/FAO (2000).

Study on spatial indicators

Figure 5-1. Endangered species (all seven species groups) against forest area change for countries with more than 1 million hectares of forest

The methodological study for spatial indicators of forest biodiversity (FAO 2001b) was carried out for FAO by UNEP-WCMC as a contribution to FRA 2000. It was based on the assumption that deforestation and forest fragmentation have a negative impact on biological diversity by altering the spatial configuration of forests. The study considered the possibility of monitoring likely impacts of such forest disturbance on biological diversity by considering the following parameters and making the listed, general assumptions.

• Area effects: Forest area was assessed, based on the assumption that patches of forest that are reduced in size will support only subsets of the species found in larger, continuous forest areas, and that these species are more vulnerable to loss because of their relatively small population size.
• Edge and gradient effects: The increase in areas where forests interface with non-forest ecosystems was assessed, based on the assumption that this will negatively affect environmental variables and biotic interactions.
• Isolation effects: The isolation of populations of a given species from other populations of the same species was assessed, based on the assumption that this will reduce geneflow (genetic exchange) among populations.[5]

Forest configuration and spatial integrity at broad geographic scales were assessed using geographic information system technology (GIS) and considering the following:

• Patch size: the area of each contiguous unit of forest cover;
• Spatially weighted forest density: the percent of cells within a given radius that are occupied by forest;
• Connectivity: distance between isolated forest fragments and larger forest areas.

The study concluded that GIS can potentially be useful in monitoring changes in these spatial indicators over time, using repeatable algorithms. However, considerable conceptual work remains to be done to link the parameters to actual impacts on biological diversity.

CONCLUSIONS

While a number of generally agreed indicators of changes in forest area, structure and composition can be assessed, there is no accepted methodolgy for directly linking these changes to their impacts on forest biological diversity in forest ecosystems, landscapes, species, populations and genes. This is especially evident when information is aggregated at the global level. Compounding this problem is the lack of agreement at national and local levels regarding the extent to which these linkages are relevant and scientifically sound, and the extent to which comprehensive assessments are technically possible and economically feasible.

The study on spatial indicators concluded that baseline assessments and monitoring of spatial integrity and naturalness would advance the state of knowledge about forest biological diversity. There is a need to monitor trends, not only in forest quantity, but also in forest quality with respect to biological diversity.

It is suggested that future action focus on the further development of and support to the testing and implementation of indicators related to each of the globally accepted criteria for sustainable forest management (FAO 2001d). In such action the level or levels of diversity targeted for conservation must be clearly specified (ecosystems, landscapes, species, genes), and action must be accompanied by regular monitoring to assess progress towards stated objectives.

Information on the status and trends of the world's forests is of basic importance to assessing the status and trends of forest biological diversity. The FRA 2000 studies described above were aimed to further contribute to this issue. However, it is recognized that the value of information on endangered species has some serious limitations in this regard, compounded by the lack of basic data. The use of spatial information is, from a technological point of view, a feasible approach for monitoring and modelling, but its relevance for the assessment of status and trends in forest biological diversity remains to be determined.

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