Estimated Original Forest Cover Map - A First Attempt Compiled September 1996 by Clare Billington, Valerie Kapos, Mary Edwards, Simon Blyth and Susan Iremonger This map has been devised as a first attempt to provide a baseline with which to compare the WCMC World Forest Map in order to calculate total forest loss. It is intended to show the distribution of closed forest worldwide prior to the impact of modern man, e.g. roughly pre 1500 in North and South America and pre 1760 in Australia. The approach was to select an existing global map of potential forest cover as a template and then to insert more detailed regional coverages. Original cover of some forest types, especially dry forests and forests occurring in largely unforested regions, is likely to be underestimated (see discussion of regional data sets, below). The intention is to continue refining this map in the light of criticism and expert input and by inserting appropriate national potential forest coverages. Method Initially, three global maps portraying original vegetation cover in some form were evaluated by comparing them with the WCMC World Forest Map (WFMap). These were: (1) the Holdridge Life Zone Global coverage, which relies on climate data to establish the likely natural vegetation cover of any area (cf. Holdridge, 1967); (2) the Major World Ecosystems Map (Olson and Watts, 1982); and (3) the World Map of Present-day Landscapes (MSU map) compiled by Moscow State University and UNEP, based on climate and soils (Milanova and Kushlin, 1993). For each candidate map, we quantified the amount of currently forested land (according to the WFMap) not originally forested according to the candidate maps. All three candidates showed some discrepancies with the WFMap, for which explanations include: (a) classification problems in the candidate maps or discrepancies with the classifications incorporated into the WFMap; (b) inaccuracies within the WFMap itself - in many regions the WFMap data are satellite-dervived and are likely to be reasonably accurate in determining the limits of present forest cover, but not all the WFMap's component data are so reliable. Of the three global candidate maps, the MSU map showed the least discrepancy with the WFMap. For this reason and because it seems to deal well with the boreal and north temperate regions, a substantial part of the world, the MSU map, at a scale of 1:15,000,000 was selected as the basic template for assembling the world original forest cover map (OFC map). The MSU map is based on two maps Geographical Belts and Zonal Types of Landscapes of the World and Land Use Types of the World compiled by Moscow State University in 1988 and 1986 respectively. The categories from the MSU map legend included in the global template are listed in the next section. Because the criterion used in selecting the global template is likely to lead to an over- estimate of OFC (the surest way to minimise discrepancy with the WFMap is to maximize OFC) and because global coverages are of necessity crude and may lack input from regional expertise, we then sought regional coverages that would be likely to be more accurate than the global one. Each regional map was compared with the WFMap data for the appropriate region on the same basis that the global map had been and if it performed as well or better according to this criterion, was inserted into the global OFC map in place of the MSU mapped data. Thus, the OFC map comprises the MSU map and the regional maps listed below. For areas where no regional map is listed, the MSU data are those shown on the final OFC map. Regional Data A number of regional coverages depicting original/potential forest cover were selected to improve the accuracy of the global OFC map. The following regional coverages were chosen, for: • Central, South America and the Caribbean - Ecoregions of Latin America and the Caribbean (Dinnerstein, et al. , 1995) Scale: 1: 15,000,000 • Africa - Vegetation of Africa (White, 1986) Scale: 1:5,000,000 • South and Southeast Asia - Review of the Indomalayan Protected Areas (MacKinnon, 1996) Scale: 1:1,000,000. • Australia - Australia Natural Vegetation (Carnahan and Australian Surveying and Land Information Group, nd) Scale: 1:5,000,000 • Europe west of the Urals - General Map of Natural Vegetation of Europe (Bohn and Katenina, 1994). Scale : 1:10,000,000 The World Map of Present Day Landscapes was used to depict OFC for the remainder of the World: USA and Canada, Russia (former USSR), East Asia (China, Mongolia, Japan, North and South Korea, Taiwan) and New Zealand. In all regional cases some discrepancies between OFC and WFMap forest occurrence remained. To acknowledge these discrepancies, to aid review and assist in the future development of the OFC map, we chose to spatially identify these discrepancies by allocating three different categories to the OFC data within the GIS coverages, in the table of statistics and in the plot. The categories comprised the following: • Category 1: where OFC data match or exceed WFMap forest cover; • Category 2: where WFMap source data are more detailed than the regional OFCs and where we are certain that forest does and did exist, especially where forest patches occur in unforested regions, e.g. riverine forest and closed forest patches in Brazilian and Venezuelan savanna regions. NB As these regions have often been severely deforested, their OFC is likely to be underestimated even when category 2 is included in the OFC estimate. • Category 3: where the discrepancy may have arisen because of differences in classification systems between OFC and the WFMap source data and/or where we are not particularly confident in the WFMap source data. Category 2 and Category 3 represent areas where no 'original forest cover' existed to explain the current forest. Thus three different OFC statistics are presented (and three categories are shown on the OFC map): (a) total area of OFC according to regional/global coverage (b) total area of OFC as in (a) plus area of category 2 (c) total area of OFC as in (a) plus area of categories 2 and 3 (maximum possible original forest cover) Forest loss can be calculated with respect to any of these three OFC estimates. Forest/Ecoregion Types Selected from the Global and Regional Coverages 1. Global template Source: World Map of Present Day Landscapes (Milanova and Kushlin, 1993). The following categories from the MSU map legend are included to form "original" forest cover of the world: Natural Landscape Zones (plains): Subpolar belts 4. Forest-tundras and open woodlands on Haplic and Leptic Podzols Temperate Belts (Boreal subbelts) 7. Taiga (boreal forests) on Haplic and Leptic Podzols, Dystric Podzoluvisols and Calcic-Gelic Cambisols, Gelic Gleysols and Albic Luvisols Temperate Belts (Subboreal subbelts) 8. Mixed deciduous-coniferous forests on Albic Luvisols, Orthic Greyzems and Dystric Cambisols 9. Broadleaved forests on Albic Luvisols, Orthic and Eutric Greyzems and Dystric Cambisols Subtropical Belts 14. Broadleaved-coniferous evergreen forests on Dystric and Ferallic Cambisols and Nitosols 15. Coniferous-broadleaved semi-evergreen forests on Ferallic Cambisols and Nitosols 16. Broadleaved semi-evergreen forests on Ferallic Cambisols, Nitosols and Chromic Luvisols 18. Mediterranean hardleaved evergreen forests, open woodlands and shrubs on Chromic Cambisols and Haplic Nitosols Tropical Belts 28. Semi-evergreen and evergreen forests on Acric Ferralsols and Rhodic Nitosols Subequatorial Belts 29. Evergreen forests on Acric Ferralsols, Rhodic Nitosols and Chromic Xerosols 30. Semi-evergreen forests on Acric Ferralsols, Rhodic and Haplic Nitosols 31. Deciduous forests on Rhodic and Haplic Nitosols and Pellic Vertisols Equatorial Belt 33. Evergreen rain forests on Xantic and Gleyic Ferralsols 34. Deciduous forests on Acric Ferralsols Intrazonal Landscapes 35. River valley landscapes - included as forested when falling within an otherwise originally forested region, not considered forested in nonforested landscapes 36. Mangrove landscapes Types of Altitudinal Landscape Spectra (medium and high mountains) - only those types involving some kind of forest are included Temperate Belts (Boreal subbelts) (5) Taiga - tundra (- golets) Temperate Belts (Subboreal subbelts) (6) Mixed forest coniferous forest - tundra (- golets) (7) Deciduous or mixed forest - coniferous forest - meadow (mixed forest - steppe) (8) Forest-steppe - coniferous forest - tundra (9) Steppe - coniferous forest - tundra (10) Steppe - mixed forest - meadow Subtropical Belts (12) Evergreen hardwoods - coniferous forests - shrub or meadow (13) Mixed forest - meadow (14) Mediterranean woodland or shrub - mixed or coniferous forest - steppe or meadow (15) Steppe or semidesert - mixed or coniferous forest - alpine meadow or steppe. (19) Steppe or semidesert - mixed - alpine meadow or steppe Tropical Belts (24) Open woodland - deciduous forest - coniferous forest - steppe or meadow (25) Forest - steppe Subequatorial Belts (26) Evergreen forest - meadow or paramos (27) Mixed forest - meadow (28) Savannah - forest - meadow or steppe 2. Mexico, Central America, South America and the Caribbean Source: Ecoregions of Latin America and the Caribbean (Dinnerstein et al ., 1995). Latin America and the Caribbean have been divided into 5 major ecosystem types, 11 major habitat types and 191 ecoregions. Ecoregions include 13 mangrove complexes but otherwise excludes marine areas and freshwater habitats. The classification scheme for ecoregions builds on existing work and