Fifty years of deforestation and forest fragmentation in Madagascar

Harper, G. J.; Steininger, Marc K.; Tucker, Compton J.; Juhn, Daniel; Hawkins, Frank

doi:10.1017/s0376892907004262

Cited by 613 publications

(577 citation statements)

References 23 publications

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“…Furthermore, the low genetic diversity observed, if confirmed in wild and conserved areas, might also be the result of over 1400 years of high deforestation rates and habitat fragmentation on the island (Campbell 1993;Gade 1996) which has been increasing over the last 50 years (Harper et al 2007). …”

Section: Discussionmentioning

confidence: 99%

Genetic diversity of the endemic honeybee: Apis mellifera unicolor (Hymenoptera: Apidae) in Madagascar

et al. 2015

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-Apis mellifera unicolor is a tropical honeybee endemic of Madagascar. Comprehensive knowledge about its mitochondrial and nuclear genetic diversity and structuration was our main purpose. Samples of worker bees were collected from 867 colonies in 76 sites in Madagascar and 1 reference population in South Africa. PCR-restriction fragment length polymorphism (RFLP) and sequencing were used to reveal variability in the COI-COII mtDNA region. Seventeen microsatellite loci were used for studying the nuclear diversity. Three PCR-RFLP profiles were observed, among which 99.4 % belonged to A1 haplotype, 0.2 % to a new A haplotype, and 0.4 % to A4 haplotype. In microsatellite analysis, moderate genetic diversity values were found for Madagascar, together with low mean number of alleles ranging from 2.47 to 3.88 compared to South Africa. Bayesian clustering assignment methods and principal component analysis (PCA) separated populations into two genetic clusters which matched with geographic areas. Several hypotheses are discussed regarding to the low genetic diversity of A. m. unicolor in its native range.Apis mellifera unicolor / microsatellite / African lineage / genetic diversity / mtDNA

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Section: Discussionmentioning

confidence: 99%

Genetic diversity of the endemic honeybee: Apis mellifera unicolor (Hymenoptera: Apidae) in Madagascar

et al. 2015

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“…Madagascar is an iconic example of the extreme environmental impacts human deforestation and habitat destruction has on soil runoff and land degradation (Green and Sussman, 1990;Harper et al, 2007). It is now estimated that only 10-15 % of the original forests remain since extensive deforestation began in the mid 20th century (Green and Sussman, 1990;Harper et al, 2007). Forest protection and management can help stabilise soils within catchment areas, yet requires continuous records of site specific land-use changes, erosion and weather patterns to differentiate between vulnerable and stable areas.…”

Section: A Grove Et Al: Spatial Linkages Between Coral Proxies Omentioning

confidence: 99%

“…The Makira Forest extends over 4600 km 2 north of Maroansetra, and together with the Masoala Peninsula National Park forms one of the largest continuous rain-forest areas remaining in Madagascar (Birkinshaw and Randrianjanahary, 2007). Since the introduction of the National Park there has been a significant reduction in the rate of deforestation, yet it still remains a constant threat to the marine and terrestrial environments (Harper et al, 2007).…”

Section: Research Area and Climate Settingmentioning

confidence: 99%

Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar

et al. 2012

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Abstract. Coral cores provide vital climate reconstructions for site-specific temporal variability in river flow and sediment load. Yet, their ability to record spatial differences across multiple catchments is relatively unknown. Here, we investigate spatial linkages between four coral proxies of terrestrial runoff and their relationships between sites. Coral cores were drilled in and around Antongil Bay, the largest bay in Madagascar, and individually analysed for fifteen years of continuous luminescence (G / B), Ba / Ca, δ 18 O sw and δ 13 C data. Each coral core was drilled close to individual river mouths (≤ 7 km), and proxy data were compared to modelled river discharge and sediment runoff data for the three corresponding catchments. A reasonable agreement between terrestrial runoff proxies with modelled river discharge and sediment yield was observed. Some inconsistencies between proxy and modelled data are likely linked to proxy behaviour, watershed size and local environmental physiochemical parameters. In general, the further a coral resided from its river source, the weaker the proxy relationship was with modelled data and other corals, due to mixing gradients and currents. Nevertheless, we demonstrate that two coral Ba / Ca and luminescence (G / B) records influenced by the same watershed are reproducible. Furthermore, a strong Ba / Ca relationship was observed between two cores from distant watersheds, with baseline averages in agreement with modelled sediment runoff data. As humic acids behave conservatively in the water column, luminescence (G / B) data gave the highest regional correlations between cores, and showed the most consistent relationship with site specific modelled discharge. No statistical relationship was observed between cores in terms of interannual δ 18 O sw and δ 13 C, meaning corals were recording a localised signal at their respective sites, confounded by vital effects. Comparing proxy baseline averages and mean seasonal cycles provided a good overview of the runoff dynamics of the bay system.

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“…Along the coast, most salt is produced in solar ponds situated in mangrove areas, although it would be possible to relocate them outside the mangroves on bare land (Semesi, 1992). The consequences of mangrove forest loss include sediment destabilization, alteration of hydrology, forest fragmentation, habitat loss for fauna, species extinction and reduced carbon sequestration, leading to increased climate change (Harper et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Genetic erosion in the snailLittoraria subvittata(Reid, 1986) due to mangrove deforestation

2016

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In tropical coastal ecosystems mangrove forests are important as feeding, spawning, breeding and nursery grounds for many marine species. High human population pressure in coastal areas has led to the loss and deterioration of mangrove habitats. Solar salt production can affect these habitats along the East African coast. Littorinid snails live on mangrove trees, forming an important component of the mangrove ecosystem and have been used as bioindicators of environmental health and community stress. Littoraria subvittata is the most abundant littorinid species in mangroves along the East African coast. Partial mitochondrial cytochrome oxidase subunit 1 (COI) gene sequences of 298 individuals were used to assess the impact of mangrove deforestation at salt ponds on the genetic diversity and structuring of L. subvittata populations, as well as to infer the demographic history of the species. Nucleotide and haplotype diversities were found to be lower in samples from mangroves at salt ponds than in samples from natural mangroves. The mean nucleotide diversity was 0.049 ± 0.036% and 0.115 ± 0.068% in mangroves at salt ponds and natural mangroves, respectively. The mean haplotype diversity was 0.23 ± 0.14 and 0.50 ± 0.14 in mangroves at salt ponds and natural mangroves, respectively. Analysis of molecular variance (AMOVA) detected a significant population structure (Ф st = 0.049; P < 0.0001) for the combined populations. Hierarchical AMOVA detected a significant population genetic structure only between populations from mangroves at salt ponds and natural mangroves (Φ ct = 0.022; P < 0.05), but not between any other groupings. Populations from natural mangrove sites showed a significant genetic structure (Ф st = 0.054, P < 0.0001), while populations from sites at salt ponds could not be differentiated (Ф st = −0.0026, P = 0.64). Reduced effective population size was observed in most samples from mangrove sites at salt ponds compared with natural mangrove. The direction of migrants was mostly from salt ponds to natural mangroves. These results show that salt ponds have a negative impact on the genetic diversity of L. subvittata populations and modify the population's genetic structure.

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Fifty years of deforestation and forest fragmentation in Madagascar

Cited by 613 publications

References 23 publications

Genetic diversity of the endemic honeybee: Apis mellifera unicolor (Hymenoptera: Apidae) in Madagascar

Genetic diversity of the endemic honeybee: Apis mellifera unicolor (Hymenoptera: Apidae) in Madagascar

Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar

Genetic erosion in the snailLittoraria subvittata(Reid, 1986) due to mangrove deforestation

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