Northeast Madagascar Research Articles

Disentangling social, environmental, and zoonotic transmission pathways of a gastrointestinal protozoan (Blastocystis spp.) in northeast Madagascar.

Understanding disease transmission is a fundamental challenge in ecology. We used transmission potential networks to investigate whether a gastrointestinal protozoan (Blastocystis spp.) is spread through social, environmental, and/or zoonotic pathways in rural northeast Madagascar. We obtained survey data, household GPS coordinates, and fecal samples from 804 participants. Surveys inquired about social contacts, agricultural activity, and sociodemographic characteristics. Fecal samples were screened for Blastocystis using DNA metabarcoding. We also tested 133 domesticated animals for Blastocystis. We used network autocorrelation models and permutation tests (network k-test) to determine whether networks reflecting different transmission pathways predicted infection. We identified six distinct Blastocystis subtypes among study participants and their domesticated animals. Among the 804 human participants, 74% (n = 598) were positive for at least one Blastocystis subtype. Close proximity to infected households was the most informative predictor of infection with any subtype (model averaged OR [95% CI]: 1.56 [1.33-1.82]), and spending free time with infected participants was not an informative predictor of infection (model averaged OR [95% CI]: 0.95 [0.82-1.10]). No human participant was infected with the same subtype as the domesticated animals they owned. Our findings suggest that Blastocystis is most likely spread through environmental pathways within villages, rather than through social or animal contact. The most likely mechanisms involve fecal contamination of the environment by infected individuals or shared food and water sources. These findings shed new light on human-pathogen ecology and mechanisms for reducing disease transmission in rural, low-income settings.

Characteristics and generation mechanisms of anticyclonic eddies, cyclonic eddies and dipole eddies in the Mozambique Channel

The discovery of cyclonic and dipole eddies in the Mozambique Channel (MC) indicates that the understanding of the mesoscale eddy characteristics in the MC is incomplete. The distributions of anticyclonic, cyclonic, and dipole eddies along the MC were elucidated in this study using satellite observations. It was observed that these eddies exhibit a preference for emergence and movement in the western MC. The occurrence frequencies of anticyclonic and cyclonic eddies are four and three times per year, respectively, in the narrowest section of the MC. In contrast, the frequency of mesoscale eddies reaches its peak at nine times per year in the central region of the MC. The occurrence of dipole eddies also reaches its peak twice per year in the middle MC. Dipole eddies are more prevalent in the MC and exhibit larger dimensions and shorter lifespans compared to anticyclonic and cyclonic eddies. Mesoscale eddies, which traverse the narrowest section of the MC and propagate southward, are predominantly generated within the western Comoros Basin due to barotropic instability. The southward branch of the Northeast Madagascar Current (NEMC) plays a crucial role in transporting these eddies to the middle MC. The eastern middle MC is also a generation site for mesoscale eddies in addition to the Comoros Basin, where cyclonic eddies are generated twice per year. These cyclonic eddies are also generated due to barotropic instability.

Scientific activism to protect the world's primates and their environments from extinction: Introduction to the special issue.

Nonhuman primates and their habitats are facing an impending extinction crisis. Approximately 69% of primate species are listed by the International Union for Conservation of Nature as threatened and 93% have declining populations. Human population growth (expected to reach 10.9 billion by the year 2100), the unsustainable demands of a small number of consumer nations for forest-risk commodities, deforestation and habitat conversion, the expansion of roads and rail networks, cattle ranching, the hunting and trapping of wild primate populations, and the potential spread of infectious diseases are among the primary drivers of primate population decline. Climate change will only exacerbate the current situation. The time to act to protect primate populations is now! In this special issue of the American Journal of Primatology, we present a series of commentaries, formulated as "Action Letters."These are designed to educate and inform primatologists, conservation biologists, wildlife ecologists, political leaders, and global citizens about the conservation challenges faced by particular primate taxa and particular world regions, and present examples of specific actions that one can take, individually and collectively, to promote the persistence of wild primate populations and environmental justice for local human populations and impacted ecological communities. As scientists, researchers, and educators, primatologists are in a unique position to lead local, national, and international efforts to protect biodiversity. In this special issue, we focus on primates of the Brazilian Amazon, lemurs of northeast Madagascar, Temminck's red colobus monkey (Piliocolobus badius temminckii), night monkeys (Aotus spp.), long-tailed macaques (Macaca fascicularis), the primate pet trade, and professional capacity building to foster conservation awareness and action. We encourage primatologists, regardless of their research focus, to engage in both advocacy and activism to protect wild primate populations worldwide.

Mixed layer heat budget in the Mozambique channel: Interannual variability and influence of Rossby waves

The evolution of the mixed layer temperature anomalies in the Mozambique Channel is analysed using a mixed layer heat budget covering sub-seasonal to interannual time scales. Sub-seasonal variations in mixed layer temperature are largely dominated by surface heat fluxes, except along the southern coast of Mozambique and Madagascar, where both the advection and the residual terms become significant. The northern Channel is dominated by the mean flow while the southern Channel is modulated by both the mean and eddy terms. Minimum heat gain through advection is observed in the channel during January–February when the Northeast Madagascar current opposes the northwesterly monsoonal winds. During the 1997/98 El Niño/positive Indian Ocean dipole, extreme warming and coral bleaching events were noted in the northern Channel. Such warming was linked with the relaxation of local winds, positive heat gain from the atmosphere and the shedding of large anticyclonic eddies northwest of Madagascar, associated with the arrival of downwelling Rossby waves. By contrast, upwelling Rossby waves and large cyclonic eddies in the Channel occurred during the 1998–2001 protracted La Niña, but only the northern part of the Channel experienced significant negative anomalies in mixed layer temperature. While no coral bleaching hotspots were noted in the northern Channel in summer 1999/2000 due to negative anomalies in advection, marine heatwaves occurred in the southern Channel during that summer. Finally, the protracted 1998–2001 La Niña was the last time that substantial upwelling Rossby wave activity occurred in the tropical South Indian Ocean; recent La Niña events showed muted or weak upwelling Rossby wave activity, including the recent 2020–2022 protracted event. Post-2001 also occurs at the same time as a stronger warming trend in the southwest Indian Ocean region.

The first description of the female of Tritonaclia kefersteinii (Butler, 1882)(Lepidoptera: Erebidae: Arctiinae: Syntomini), the type species of its genus.

The previously unknown female of Tritonaclia kefersteinii (Butler, 1882), the type species of the genus Tritonaclia Hamspon, 1898 is described for the first time, based on a specimen from Marojejy National Park (North-east Madagascar). The female genitalia are described in detail and illustrated. The taxonomic affiliation of the newly discovered female and its conspecificity with the male are confirmed by both morphological and molecular characters. For the first time, clear diagnostic characters of the male genitalia are also provided and illustrated. Comments on the known distribution of the species are provided. The new findings allow the genus to be properly characterized as a contribution to the taxonomy of Madagascar Syntomini.

A habitat stronghold on the precipice: A call-to-action for supporting lemur conservation in northeast Madagascar.

The northeast of Madagascar is as diverse as it is threatened. The area bordering the Analanjirofo and SAVA regions contains six protected areas and at least 22 lemur species. Many applied research and conservation programs have been established in the region with the aim of ensuring both wildlife and people thrive in the long term. While most of the remaining humid evergreen forest of northeast Madagascar is formally protected, the local human population depends heavily on the land, and unsustainable natural resource use threatens this biodiversity hotspot. Drawing from our collective experiences managing conservation activities and research programs in northeast Madagascar, we discuss the major threats to the region and advocate for eight conservation activities that help reduce threats and protect the environment, providing specific examples from our own programs. These include (1) empowering local conservation actors, (2) ensuring effectively protected habitat, (3) expanding reforestation, (4) establishing and continuing long-term research and monitoring, (5) reducing food insecurity, (6) supporting environmental education, (7) promoting sustainable livelihoods, and (8) expanding community health initiatives. Lastly, we provide a list of actions that individuals can take to join us in supporting and promoting lemur conservation.

Spatial and seasonal variability of horizontal temperature fronts in the Mozambique Channel for both epipelagic and mesopelagic realms

IntroductionOcean fronts are moving ephemeral biological hotspots forming at the interface of cooler and warmer waters. In the open ocean, this is where marine organisms, ranging from plankton to mesopelagic fish up to megafauna, gather and where most fishing activities concentrate. Fronts are critical ecosystems so that understanding their spatio-temporal variability is essential not only for conservation goals but also to ensure sustainable fisheries. The Mozambique Channel (MC) is an ideal laboratory to study ocean front variability due to its energetic flow at sub-to-mesoscales, its high biodiversity and the currently debated conservation initiatives. Meanwhile, fronts detection relying solely on remotely-sensed Sea Surface Temperature (SST) cannot access aspects of the subsurface frontal activity that may be relevant for understanding ecosystem dynamics.MethodIn this study, we used the Belkin and O’Reilly Algorithm on remotely-sensed SST and hindcasts of a high-resolution nested ocean model to investigate the spatial and seasonal variability of temperature fronts at different depths in the MC.ResultsWe find that the seasonally varying spatial patterns of frontal activity can be interpreted as resulting from main features of the mean circulation in the MC region. In particular, horizontally, temperature fronts are intense and frequent along continental shelves, in islands’ wakes, at the edge of eddies, and in the pathways of both North-East Madagascar Current (NEMC) and South-East Madagascar Current (SEMC). In austral summer, thermal fronts in the MC are mainly associated with the Angoche upwelling and seasonal variability of the Mozambique current. In austral winter, thermal fronts in the MC are more intense when the NEMC and the Seychelles-Chagos and South Madagascar upwelling cells intensify. Vertically, the intensity of temperature fronts peaks in the vicinity of the mean thermocline.DiscussionConsidering the marked seasonality of frontal activity evidenced here and the dynamical connections of the MC circulation with equatorial variability, our study calls for addressing longer timescales of variability to investigate how ocean ecosystem/front interactions will evolve with climate change.

Conservation value of vanilla agroecosystems for vertebrate diversity in north-east Madagascar

AbstractAs a result of increasing global demand for food, large areas of natural habitat are being converted to agroecosystems to accommodate crop cultivation. This agricultural expansion is most prominent in the tropics, where many rural communities are dependent solely on farming income for their livelihoods. Such agricultural land conversion can have severe implications for local fauna. In this study, we compared vertebrate species diversity between natural forest habitat and three types of vanilla plantations maintained under varying management regimes in north-east Madagascar. We used diurnal and nocturnal transects to survey vertebrate diversity. Natural forest habitat contained the greatest vertebrate species diversity, and had proportionally more threatened and endemic species than all vanilla plantation types. However, we observed a greater number of species and a higher inverse Simpson index in minimally managed vanilla plantations located within or near natural forest compared to intensively managed vanilla plantations. These findings are important and encouraging for animal conservation and sustainable crop cultivation in Madagascar, and suggest that newly created vanilla plantations, and already existing plantations, should endeavour to follow the more traditional, minimalistic management approach to improve sustainability and promote higher faunal diversity.

Diversity of Coral Reef Fishes in the Western Indian Ocean: Implications for Conservation

Communities of coral reef fishes are changing due to global warming and overfishing. To understand these changes and inform conservation, knowledge of species diversity and distributions is needed. The western Indian Ocean (WIO) contains the second highest coral reef biodiversity hotspot globally, yet a detailed analysis of the diversity of coral reef fishes is lacking. This study developed a timed visual census method and recorded 356 species from 19 families across four countries in the WIO to examine patterns in species diversity. Species richness and composition differed most between the island countries of Madagascar and Comoros and both these locations differed from locations in Tanzania and Mozambique which were similar. These three regional groupings helped define WIO ecoregions for conservation planning. The highest species richness was found in Tanzania and Mozambique, and the lowest and most different species composition was found in Comoros. Biogeography explains these differences with naturally lower species diversity expected from the small, oceanic, and isolated islands of Comoros. Present day ocean currents maintain these diversity patterns and help explain the species composition in northeast Madagascar. Species distributions were driven by 46 of the 356 species; these provide guidance on important species for ongoing monitoring. The results provide a benchmark for testing future changes in reef fish species richness.

Observation of Traditional Caregiver-Infant Feeding Behaviours and Porridge and Energy Intakes during One Meal to Define Key Messages for Promoting Responsive Feeding in the Amparafaravola District, Rural Madagascar.

Undernutrition is highly prevalent in young children in Madagascar and insufficient intake per meal could be one of the main causes. A cross-sectional survey of infant feeding practices including video-recorded meal observations was carried out with 101 caregiver–infant pairs in the Amparafaravola district, Northeast Madagascar. The objective was to quantify the porridge/energy intake of 9–11-month-old children and assess its association with the caregiver–infant feeding behaviours. Then, key messages for promoting responsive feeding (RF) were developed and tested through focus group discussions. The mean porridge intake was 12.8 ± 7.5 g/kg body weight (BW)/meal, corresponding to hardly one-third of the 300 kcal recommended from complementary foods for 9–11-month-old children. Analysis of meal videos suggested that mothers practiced the five positive feeding behaviours (self-feeding, responsive, active, social, and distraction), and rarely the negative ones. Only 6.9% of mothers used positive RF “very frequently”, although it was associated with higher intakes (p < 0.05), with mean intake reaching 21 g/kg BW. In focus groups, caregivers approved the six RF messages and related counselling cards. They suggested some modifications to improve their understanding, and counselling cards were revised accordingly. The long-term impact of RF-promoting card use on the meal intakes and the nutritional status of young children must now be assessed.

The influence of seasonality, anthropogenic disturbances, and cyclonic activity on the behavior of northern sportive lemurs (Lepilemur septentrionalis) at Montagne des Français, Madagascar.

Anthropogenic tropical deforestation and degradation imminently threaten primates today. Primates living in these disturbed habitats may also be subjected to increasingly severe tropical storms such as cyclones or hurricanes. These disturbances pose an immediate risk to their livelihood and can dramatically alter their habitats, in turn potentially shifting behavioral patterns. We had the unique opportunity to study the effects of seasonality, anthropogenic disturbances, and the immediate effects of a cyclone on the behavior of the critically endangered northern sportive lemur (NSL) in an anthropogenically disturbed forest in Madagascar. Cyclone Enawo made landfall on March 7, 2017 in northeast Madagascar with sustained wind speeds of 230 km/h. We collected behavioral data on nine individual NSLs during both wet and dry seasons, before and after Cyclone Enawo, and in areas of differing human activity, using scan sampling at 5-min intervals. We ran generalized linear mixed models to test the effects of seasonality and disturbances on behavior. We found that NSLs spent more time feeding in dry months compared with wet (Z = -4.21, p < 0.001). More specifically, they spent more time-consuming leaves and vine species in the dry season (Z = -2.26, p = 0.02; Z = -2.3; p = 0.02). We also found that NSLs were observed at lower heights in trees after the cyclone (Z = -2.45; p = 0.016) and spent more time in the interior portions of trees (Z = 3.44; p < 0.001), perhaps due to extensive limb damage of emergent trees documented after the cyclone. Our analyses show that seasonality affected most aspects of NSL behavior, followed by the effects of Cyclone Enawo, with anthropogenic disturbances having little effect. Our data suggest that the behavioral flexibility of NSLs in response to predictable seasonality may enable them to respond similarly to stochastic climatic disturbances. However, their generalist diet may allow them to persist in anthropogenically disturbed landscapes without the need to greatly alter their behavior.

Procedural Knowledge of Primary School Teachers in Madagascar for Teaching and Learning towards Land-Use- and Health-Related Sustainable Development Goals

Achieving the Sustainable Development Goals (SDGs) requires the empowerment of learners through Education for Sustainable Development (ESD), already at primary level. Teacher education for the SDGs is a focus of ESD. However, many teachers in Madagascar are underqualified and show knowledge gaps regarding ESD. This paper aims at identifying starting points for an ESD-oriented further development of teacher training, considering regionally relevant issues. Teaching Sustainable Development issues requires procedural knowledge. This paper reports on (i) Malagasy primary school teachers’ (n = 286) teaching and learning prerequisites regarding land-use and health issues compared to expert knowledge, (ii) modeling teachers’ respective procedural knowledge with the Rasch Partial Credit Model and validation studies, and on (iii) comparison of groups of teachers differentiated by diversity dimensions, e.g., teaching at rural or urban schools. The teachers underestimated land-use and health courses of action regarding effectiveness and possibility of implementation, compared to experts. IRT modeling resulted in two distinct knowledge dimensions, i.e., land use and health (latent correlation: 0.31). Rural teachers showed higher procedural land-use knowledge than urban teachers. No differences occurred regarding health knowledge. The paper argues for ESD-focused reorientation of teacher training, considering regional specificities of land-use topics, e.g., regarding vanilla and rice cultivation in North-East Madagascar, and health topics.

Food insecurity related to agricultural practices and household characteristics in rural communities of northeast Madagascar.

Ending hunger and alleviating poverty are key goals for a sustainable future. Food security is a constant challenge for agrarian communities in low-income countries, especially in Madagascar. We investigated agricultural practices, household characteristics, and food security in northeast Madagascar. We tested whether agricultural practices, demographics, and socioeconomics in rural populations were related to food security. Over 70% of respondents reported times during the last three years during which food for the household was insufficient, and the most frequently reported cause was small land size (57%). The probability of food insecurity decreased with increasing vanilla yield, rice yield, and land size. There was an interaction effect between land size and household size; larger families with smaller land holdings had higher food insecurity, while larger families with larger land had lower food insecurity. Other socioeconomic and agricultural variables were not significantly related to food insecurity, including material wealth, education, crop diversity, and livestock ownership. Our results highlight the high levels of food insecurity in these communities and point to interventions that would alleviate food stress. In particular, because current crop and livestock diversity were low, agricultural diversification could improve outputs and mitigate food insecurity. Development of sustainable agricultural intensification, including improving rice and vanilla cultivation to raise yields on small land areas, would likely have positive impacts on food security and alleviating poverty. Increasing market access and off-farm income, as well as improving policies related to land tenure could also play valuable roles in mitigating challenges in food security.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12571-021-01179-3.

Notes on a small collection of Prioninae from North-East Madagascar with the description of a new Schizodontus/ Quentin amp; Villiers, 1974 (Cerambycidae, Closterini).

We present observations from a small collection of longhorns belonging to the subfamily Prioninae and collected during an expedition in the rainy season to a newly designated protected area, Mahimborondro, in North-East Madagascar. The material includes a new species (S. mahimborondroensis sp. nov.) of Closterini (Prioninae) from a small genus with only two described species (Schizodontus angustus Quentin Villiers, 1974 and S. latus Quentin Villiers, 1974). An identification key to the three species is included.

Effects of land use, habitat characteristics, and small mammal community composition on Leptospira prevalence in northeast Madagascar.

Human activities can increase or decrease risks of acquiring a zoonotic disease, notably by affecting the composition and abundance of hosts. This study investigated the links between land use and infectious disease risk in northeast Madagascar, where human subsistence activities and population growth are encroaching on native habitats and the associated biota. We collected new data on pathogenic Leptospira, which are bacteria maintained in small mammal reservoirs. Transmission can occur through close contact, but most frequently through indirect contact with water contaminated by the urine of infected hosts. The probability of infection and prevalence was compared across a gradient of natural moist evergreen forest, nearby forest fragments, flooded rice and other types of agricultural fields, and in homes in a rural village. Using these data, we tested specific hypotheses for how land use alters ecological communities and influences disease transmission. The relative abundance and proportion of exotic species was highest in the anthropogenic habitats, while the relative abundance of native species was highest in the forested habitats. Prevalence of Leptospira was significantly higher in introduced compared to endemic species. Lastly, the probability of infection with Leptospira was highest in introduced small mammal species, and lower in forest fragments compared to other habitat types. Our results highlight how human land use affects the small mammal community composition and in turn disease dynamics. Introduced species likely transmit Leptospira to native species where they co-occur, and may displace the Leptospira species naturally occurring in Madagascar. The frequent spatial overlap of people and introduced species likely also has consequences for public health.

Two New Species of Begonia sect. Erminea (Begoniaceae) from the Masoala Peninsula, Madagascar

Begonia duruisseaui Scherber. and B. rahajasoae Scherber., both endemic to the Masoala Peninsula in northeast Madagascar, are described and illustrated. They both belong to Begonia L. sect. Erminea A. DC. The former is related to B. tsimihety Humbert from which it differs by its fewer, larger leaves, with finely denticulate margins and a villous inflorescence. The latter is morphologically related to B. bogneri Ziesenh. and the recently described B. ambodiforahensis Scherber. &amp; Duruiss., although it differs from both by the combination of very narrow leaves with clearly demarcated petioles and blades, which are villous and pilose, respectively.

New lineages within the Malagasy freshwater crab fauna: Agora n. gen. for Thelphusa goudoti H. Milne Edwards, 1853, and a phytotelmic new species of Malagasya Cumberlidge &amp; Sternberg, 2002 (Brachyura: Potamonautidae: Deckeniinae)

AbstractNew molecular and morphological analyses of the relationships of 77 specimens of potamonautid freshwater crabs collected from all parts of Madagascar support the monophyly of the island’s freshwater crab fauna and verify most of the existing taxa. The phylogenetic tree identified several new lineages that represent four new genera and 10 new species, and found Foza Reed &amp; Cumberlidge, 2006 to be paraphyletic. The present work is the first of a series of articles reporting on these discoveries that provide an improved understanding of the relationships between the endemic potamonautid species found on this tropical island. We describe a new species of Malagasya Cumberlidge &amp; Sternberg, 2002 from a phytotelmic habitat in northeast Madagascar, and establish Agoragen. nov. to accommodate Thelphusa goudoti H. Milne Edwards, 1853. Both of these new taxa are recognized based on combinations of morphological characters and molecular data. The new species of Malagasya is distinguished from the other two species of this genus, which are illustrated here for comparative purposes. Agora goudotin. comb. is endemic to Madagascar, and is compared with and distinguished from the eight other genera of freshwater crabs occurring in that country.

Land-Use and Health Issues in Malagasy Primary Education—A Delphi Study

Education for Sustainable Development (ESD) plays a key role in Sustainable Development. In low-income countries like Madagascar, this key role is particularly relevant to primary education. However, the curricula lack a comprehensive ESD approach that incorporates regional issues. In Madagascar, sustainable land-use practices (Sustainable Development Goals 12, 15) and health prevention (SDGs 2, 3, 6) are educational challenges. Procedural knowledge allows problem-solving regarding unsustainable developments. We adapted and further developed a measure of ESD-relevant procedural knowledge. Considering curricula, sustainability standards, research, and a two-round Delphi study (n = 34 experts), we identified regionally relevant land-use practices and health-protective behavior. After the experts rated the effectiveness and possibility of implementation of courses of actions, we calculated an index of what to teach under given Malagasy (regional) conditions. Combined with qualitative expert comments, the study offers insights into expert views on land-use and health topics: For example, when teaching ESD in Northeast Madagascar, sustainable management of cultivation and soil is suitable, particularly when linked to vanilla production. Health-protective behavior is ultimately more difficult to implement in rural than in urban areas. These results are important for further curricula development, for ESD during primary education, and because they give insights into the topics teacher education should address.

Epiphytic bryophyte diversity and range distributions along an elevational gradient in Marojejy, Madagascar

AbstractDescribing spatial variation in species richness and understanding its links to ecological mechanisms are complementary approaches for explaining geographical patterns of richness. The study of elevational gradients holds enormous potential for understanding the factors underlying global diversity. This paper investigates the pattern of species richness and range‐size distribution of epiphytic bryophytes along an elevational gradient in Marojejy National Park, northeast Madagascar. The main objectives are to describe bryophyte species composition and endemism in Marojejy National Park, to describe the species richness and distribution patterns of epiphytic bryophytes along an elevational gradient from 250 m to 2050 m and to evaluate the explanatory value of environmental variables for the observed patterns. Bryophyte samples were collected following a nested design with four hierarchical levels: elevational belts, plots, quadrats, and microplots. In total, 254 epiphytic bryophyte species were recorded, comprising 157 liverworts and 97 mosses. Twenty‐three of these are endemic to Madagascar. Species richness exhibits a hump‐shaped pattern along the elevational gradient, peaking at 1,250 m. Eighty‐seven percent of the total recorded species have a range distribution lower than 1,000 m, at which point 36% are restricted to these single elevations. Our results suggest that mean temperature, relative humidity, and vapor pressure deficit play important roles in shaping the richness pattern observed in this study. While the liverwort richness pattern did not correlate to vapor pressure deficit and responded only weakly to relative humidity, the richness pattern shown by mosses correlates well with mean temperature, relative humidity, and vapor pressure deficit.

Participatory Bayesian network modeling to understand driving factors of land-use change decisions: insights from two case studies in northeast Madagascar

ABSTRACTForest frontiers worldwide reveal trade-offs that are key in mitigating global change. In the forest frontiers of northeast Madagascar, land-use changes result from decisions made by smallholder farmers. In the past, subsistence needs led to increasing shifting cultivation, resulting in forest degradation and deforestation. This study focuses on investigating the role of locally determined factors in land-use change decisions in the forest frontier context. Therefore, we developed a Bayesian network-based land-use decision model that represents the causalities between factors influencing land-use decisions and takes into account local decision-makers’ knowledge. The approach is applied in two comparative case studies in northeast Madagascar. Results show that farmers mostly aim at extending the cultivation of cash crops. These results and the causal mechanisms disentangled for the forest frontier of northeast Madagascar help understand change mechanisms and hence, support decision-making to attain the Sustainable Development Goals.