Projecting forest cover in Madagascar 157
underestimate forest loss. We then calculated the forest loss of each protected area for the 33 years of 2017–2050 using compound computation of interest as follows: Forest size in 2050 = Forest size in 2017 ×((100 – mean of annual forest loss in per cent)/100)33.
Lemur subpopulations
FIG. 1 Size distribution of protected areas in Madagascar (a) as a whole and (b) as forest blocks in 2017 and projected to 2050 based on current deforestation rates (Table 2). Size classes double from one class to the next. Values on the x-axes are the midpoints in each category (e.g. 5 km2 represents blocks of 0–9.99 km2, 15 km2 represents blocks of 10–19.99 km2, etc.).
1990–2000, 0.03% during 2000–2005, 0.04% during 2005– 2010, 0.14% during 2010–2015 and 0.18% during 2015–2017. Thus, the deforestation rate during 2015–2017 was higher than in previous years. The trends in deforestation rates in the protected areas over time match the deforestation trends for all of the forests of Madagascar (including forest outside protected areas), although our deforestation rates within IUCN category I–III protected areas were approxi- mately an order of magnitude lower than the deforestation rates reported for Madagascar as a whole (Vieilledent et al., 2018). For the projections of future degradation, we assumed the deforestation rates during 2015–2017 remain constant for each protected area until 2050. If the deforestation rates during 2015–2017 were exceptionally high, their application to the projection might overestimate future deforestation rates. If deforestation rates increase over time, as indicated by the trend for 2000–2017, the appli- cation of constant deforestation rates until 2050 would
As of 2018, 107 lemur species are recognized on the IUCN Red List. This number is likely to change because of revi- sions, the use of new taxonomic methods and/or new dis- coveries (Tattersall & Cuozzo, 2018; Hending et al., 2022; Poelstra et al., 2022), but the principal conclusions of our analyses should remain valid. We took the occurrence of lemur species from the Noe4D biodiversity database (Wilmé et al., 2006; Waeber et al., 2020), supplemented by Goodman et al. (2018). Given the localized occurrence of some lemur species (Wilmé et al., 2006, 2012;Mittermeier et al., 2010), we did not consider species to be present in any given protected area on the basis of their geographical range but only when they had been reported to occur in the protected area. Lemur occurrences are not available for individual forest blocks but rather for the protected area as a whole. Although it is unlikely that all lemur species listed as occurring within any given protected area occur in all of its forest blocks, in the absence of more detailed data we assume this. This results in an overestimate of the number of lemur subpopulations. We did not consider taxa that were not identified to
species. This approach eliminated some representatives of the genera Avahi, Cheirogaleus, Hapalemur, Lepilemur, Microcebus, Mirza and Phaner from some sites. We did not include Hapalemur alaotrensis in the analyses as this species is restricted to reed habitat. We excluded protected areas without lemurs or for
which inventories are not available. These are Ambohidray (1,241 ha, no information on lemur occurrences), Ampan- angandehibe-Behasina (580 ha, no forest), Andreba (39 ha, no forest), Ibity (6,137 ha, no forest), Mahialambo (304 ha, no forest), Maningozy (5,973 ha, 773 ha of forest in 2017), Manjakatompo Ankaratra (8,131 ha, 815 ha of for- est in 2017, no lemur species recorded by the Mission zoologique Franco-Anglo-Américaine in 1929 or during a biodiversity inventory in 1996; Goodman et al., 1996).
Results
Forest cover and loss during 2015–2017 In 2017 the 102 protected areas considered ranged from 0.97 to 4,194.12 km2, with a median size of 236.29 km2 and an interquartile range of 43.25–750.49 km2. Most protected areas were 320–640 km2 (Fig. 1). At this time there were 170 forest blocks within the protected areas (Fig. 1). The
Oryx, 2024, 58(2), 155–163 © The Author(s), 2023. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605323001175
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