Projecting forest cover in Madagascar's protected areas to 2050 and its implications for lemur conservation
S ERGE C. RAFANOHARANA1 ,F.OLL IER D. AN D RIA NAMBI NINA2 H. ANDRY RASAMUEL1 ,PATRICK O. WAE BER 3 , 4 L UCIE NNE WILMÉ 1 , 5 and JÖRG U. GANZHORN* 6 , 7
Abstract Predicting future conservation needs can help in- form conservation management but is subject to uncer- tainty. We measured deforestation rates during 2015–2017 for 114 protected areas in Madagascar, linked deforestation to the status of protection according to IUCN categories I–VI, used recent deforestation rates to extrapolate forest cover over 2017–2050 and linked the size of forest blocks to the projected persistence of lemur subpopulations. In the six IUCN categories for protected areas in Madagascar the median size of forest blocks is 9–37 km2 and median an- nual deforestation rates range from 0.02% in the single IUCN category III site to 0.19% in category II and 1.95% in category VI sites. In 2017, 40% of all forest blocks within protected areas were ,10 km2, and this is projected to increase to 45%in 2050. Apart from these small forest fragments, the modal site of forest blocks was 160–320 km2 in 2017, and this is projected to decrease to 80–160 km2 in 2050. The range of . 50% of all lemur species exclusively contains forest blocks of,10 km2. The modal size of forest blocks.10 km2 is predicted to remain at 120 km2 until 2050. Although uncertainty remains, these analyses provide hope that forest blocks within the protected areas of Madagascar will remain large enough to maintain lemur subpopulations for most species until
2050.Thisshould allow sufficient time for the implementation of effective conservation measures.
Keywords Biodiversity, deforestation, forest change, IUCN protected area category, lemur, Madagascar, primate con- servation, viable population
The supplementary material for this article is available at
doi.org/10.1017/S0030605323001175
*Corresponding author,
joerg.ganzhorn@
uni-hamburg.de 1World Resources Institute Africa, Antananarivo, Madagascar 2Madagascar National Parks, Antananarivo, Madagascar 3Department of Agricultural, Forest and Food Sciences HAFL, Bern University
of Applied Sciences, Zollikofen, Switzerland 4Department of Environmental Systems Science, Swiss Federal Institute of
Technology (ETH), Zürich, Switzerland 5Madagascar Research and Conservation Program, Missouri Botanical Garden,
Antananarivo, Madagascar 6Universität Hamburg, Hamburg, Germany 7IUCN Species Survival Commission Primate Specialist Group
Received 13 December 2022. Revision requested 12 May 2023. Accepted 10 August 2023. First published online 10 November 2023.
Introduction
2003. Although this increase is remarkable, it remains uncertain whether current conservation efforts will be able to save the unique biodiversity of Madagascar (Gardner et al., 2018). Conservation assessments of terrestrial ecosys- tems mostly distinguish between forest and non-forest areas. This binary typology of forest vs non-forest is overly simplistic for classifying Malagasy terrestrial vegetation (e.g. Lowry et al., 1997;Moat & Smith, 2007), but the majority of the endemic vertebrate fauna of Madagascar is forest de- pendent, and the dichotomous classification of forest vs non-forest is often used as a proxy for conservation mea- sures (Goodman et al., 2018; Rafanoharana et al., 2023). Although the original protected areas belonging to IUCN categories I–III seem to have provided reasonable protection over the last few decades (Goodman et al., 2018), most of the protected areas added recently are of IUCN categories IV– VI. Categories V and VI assign governance responsibilities to communities and allow multiple uses of the areas, such as supposedly sustainable extraction of natural resources to secure traditional livelihoods (Table 1). As this is a new approach for Madagascar, the protected areas under the responsibility of communities and/or NGOs often lack crucial resources and capacities and thus seem to be less ef- fective for biodiversity conservation than protected areas of IUCN categories I–III (Gardner et al., 2018; Rafanoharana et al., 2021; Stoudmann et al., 2023). Thus, it is unclear what role these new protected areas could have in species conservation and how the biodiversity of Madagascar will be affected by ongoing deforestation (Vieilledent et al., 2018). Given that a large proportion of the biodiversity of Madagascar remains unknown, species-based conservation management is mostly based on conspicuous taxa, such as higher plants or vertebrates, which can also be considered umbrella species (Kremen et al., 2008; Miller & Morgan, 2011; Vieilledent et al., 2013; Jenkins et al., 2014; Schwitzer et al., 2014; Tagliari et al., 2021). Because of their close re- latedness to people and their precarious conservation sit- uation, primates in general and lemurs of Madagascar in particular are regularly assessed (Schwitzer et al., 2014;
T
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (
http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. 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
o counteract future biodiversity loss, Madagascar has quadrupled the area of its protected area system since
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