Spiny Forest Research Articles

Croton crossolepis (Euphorbiaceae), a new species with an unusual trichome type from southwestern Madagascar

Croton crossolepis is newly described and illustrated. It is a shrub or small tree endemic to southwestern Madagascar near Toliara and is distinguished by a mixture of stellate and lepidote trichomes, with most of the lepidote ones having fringed margins and partially free, stiff rays that can make it adhere to surfaces like clothing when they come into contact. The inflorescences are pseudoterminal and spicate in appearance, with numerous flowers subtended by acicular bracts that are longer than the buds. It has larger leaves than most Croton species that occur in the semi-arid southwestern scrub and spiny forests nearby in the country, and it is apparently quite rare and subject to ongoing decline, warranting a conservation assessment of Vulnerable.

Digitaria bosseri (Poaceae: Panicoideae), a new grass from Madagascar

SummaryA new panicoid grass species of uncertain generic affiliation is described and illustrated from the dry and spiny forest ecosystems of southern Madagascar. It is tentatively placed in the genus Digitaria based on its spikelet structure, pending DNA sequence data.

PES for the poor? Preferences of potential buyers of forest ecosystem services for including distributive goals in the design of payments for conserving the dry spiny forest in Madagascar

Whether to consider distributive goals when designing the policy instrument of payments for ecosystem services is controversial. Opponents argue this may undermine the efficiency of ecosystem service provision and poverty reduction should be addressed with separate policies. However, many developing country governments are unable to implement such policies. In such cases, from an economic perspective, the preferences of buyers of ecosystem services should count. This paper addresses with a case study a particular group of buyers, citizens in developed countries, who pay to protect public environmental goods in developing countries through donations. Based on the case study of Malagasy spiny forest conservation, we conduct a choice experiment to elicit the preferences of citizens of Cottbus, Germany, for inclusion of distributive goals in PES design. We find that overall respondents have preferences for achieving distributive goals (equal or pro-poor distribution) with their donations and value information about the way of payments distribution among local beneficiaries.

Seasonal adaptations in energy budgeting in the primate Lepilemur leucopus.

The spiny forest of South Madagascar is one of the driest and most unpredictable habitats in Africa. The small-bodied, nocturnal primate Lepilemur leucopus lives in this harsh habitat with high diurnal and seasonal changes in ambient temperature. In this study, we investigated seasonal adaptions in energy budgeting of L. leucopus, which allow it to live under these conditions by measuring resting metabolic rate using open-flow respirometry. No signs of heterothermy were detected, and resting metabolic rate was significantly lower in the warmer wet season than in the colder dry season. In fact, L. leucopus possesses one of the lowest mass-specific metabolic rates measured so far for an endotherm, probably the result of adaptations to its habitat and folivorous and potentially toxic diet. Surprisingly, we identified a shift of the thermoneutral zone from between 25 and 30 °C in the wet season to between 29 and 32 °C in the cool dry season. L. leucopus seems to be more affected by the hot daytime temperatures during the dry season and thermoregulation seems to be more costly during this time, which makes this shift of the thermoneutral zone advantageous. Our findings suggest that L. leucopus has a very small scope to unfavorable conditions, making it highly vulnerable, e.g., to changing conditions due to climate change.

Compensation of thermal constraints along a natural environmental gradient in a Malagasy iguanid lizard (Oplurus quadrimaculatus)

Physiological or behavioural adjustments are a prerequisite for ectotherms to cope with different thermal environments. One of the world's steepest environmental gradients in temperature and precipitation can be found in southeastern Madagascar. This unique gradient allowed us to study the compensation of thermal constraints in the heliothermic lizard Oplurus quadrimaculatus on a very small geographic scale. The lizard occurs from hot spiny forest to intermediate gallery and transitional forest to cooler rain forest and we investigated whether these habitat differences are compensated behaviourally or physiologically. To study activity skin temperature (as proxy for body temperature) and the activity time of lizards, we attached temperature loggers to individuals in three different habitats. In addition, we calculated field resting costs from field resting metabolic rate to compare energy expenditure along the environmental gradient. We found no variation in activity skin temperature, despite significant differences in operative environmental temperature among habitats. However, daily activity time and field resting costs were reduced by 35% and 28% in the cool rain forest compared to the hot spiny forest. Our study shows that O. quadrimaculatus relies on behavioural mechanisms rather than physiological adjustments to compensate thermal differences between habitats. Furthermore, its foraging activity in open, sun exposed habitats facilitates such a highly effective thermoregulation that cold operative temperature, not energetically expensive heat, presents a greater challenge for these lizards despite living in a hot environment.

Scent marking preferences of ring-tailed lemurs (Lemur catta) in spiny forest at Berenty Reserve

Scent marking preferences of ring-tailed lemurs (Lemur catta) in spiny forest at Berenty Reserve

Are buyers of forest ecosystem services willing to consider distributional impacts of payments to local suppliers? Results from a choice experiment in Antananarivo, Madagascar

SUMMARYA controversial issue in the debate on payments for ecosystem services (PESs) is whether distributional goals should be considered in the design of such schemes. We contribute to this debate by analysing the preferences of citizens of Antananarivo (Madagascar) as potential buyers of forest ecosystem services from a developing country. We conducted a choice experiment to investigate citizens’ willingness to pay to conserve the endemic spiny forests in southwest Madagascar and their preferences for including distributional goals in the design of a PES scheme aimed at spiny forest conservation. We found that respondents were willing to pay for forest conservation and preferred a PES scheme in which the poorest households in a community would receive the largest share of payments over a scheme in which every household would receive the same share, which, in turn, they preferred over a PES scheme in which they would have no information about its distributional impact. In comparing these results with those of a similar survey in a developed country (in Cottbus, Germany), we find that the preference ranking regarding distributional impacts is identical. However, citizens in Cottbus attach greater importance to the consideration of distributive goals in PESs than citizens in Antananarivo.

Corrigendum

Journal of EcologyVolume 105, Issue 2 p. 559-560 CorrigendumFree Access Corrigendum This article corrects the following: Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar Ghislain Vieilledent, Oliver Gardi, Clovis Grinand, Christian Burren, Mamitiana Andriamanjato, Christian Camara, Charlie J. Gardner, Leah Glass, Andriambolantsoa Rasolohery, Harifidy Rakoto Ratsimba, Valéry Gond, Jean-Roger Rakotoarijaona, Emily Lines, Volume 104Issue 3Journal of Ecology pages: 703-715 First Published online: February 25, 2016 First published: 24 October 2016 https://doi.org/10.1111/1365-2745.12679Citations: 1AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Vieilledent, G., Gardi, O., Grinand, C., Burren, C., Andriamanjato, M., Camara, C., Gardner, C.J., Glass, L., Rasolohery, A., Ratsimba, H.R., Gond, V. & Rakotoarijaona, J.R. (2016) Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar. Journal of Ecology, 104, 703–715. doi:10.1111/1365-2745.12548. In the paper by Vieilledent et al. (2016), the authors inadvertently inverted the captions of Figs 2 and 3. The authors and journal would like to correct this error. The results and conclusions of the article are not affected. The figures with their correct captions are below. Figure 2Open in figure viewerPowerPoint Forest carbon map in 2010 for Madagascar. We derived a national forest carbon map in 2010 for Madagascar at 250-m resolution. We fitted our model using above-ground carbon density for 1771 forest plots measured between 1996 and 2013. Our model included six explicative variables: two vegetation indexes (VCF and EVI from 2000 to 2010 MODIS satellite images at 250 m), one topographic variable (elevation from SRTM at 90 m) and three climatic variables [mean annual temperature, mean annual precipitation and temperature seasonality from WorldClim at 30 arc-seconds (~1 km)]. Our predictions are limited to the extent of the forest in 2010. Clear differences appear for the forest carbon stocks between the three ecoregions including moist, dry and spiny forest (see black lines for delimitations). Figure 3Open in figure viewerPowerPoint Relationships between explicative variables and ACD. Graphics show the marginal effect of the variable on ACD. Range of predicted ACD is reduced compared to the observed range of ACD in forest plots because variables other than the target variable are set to their mean values. Hash marks at the bottom of the plot indicate the deciles of the explicative variable. Percentage in the top-left or top-right corner of each panel is the percentage of increase in mean square error when the variable was randomly permuted, which indicates the variable relative importance in determining ACD. Reference Vieilledent, G., Gardi, O., Grinand, C., Burren, C., Andriamanjato, M., Camara, C., Gardner, C.J., Glass, L., Rasolohery, A., Ratsimba, H.R., Gond, V. & Rakotoarijaona, J.R. (2016) Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar. Journal of Ecology, 104, 703– 715. doi:10.1111/1365-2745.12548 Citing Literature Volume105, Issue2March 2017Pages 559-560 FiguresReferencesRelatedInformation

Contrasting spatial and temporal trends of protected area effectiveness in mitigating deforestation in Madagascar

Networks of protected areas (PAs) form the backbone for biodiversity conservation worldwide. The effectiveness of protected areas has been studied and it has been shown that confounding factors, such as remoteness and accessibility, correlated with both presence of protection and extractive behaviors, affect the outcomes. We investigated the effectiveness of Madagascar's PA network in decreasing deforestation pressures, using a novel counterfactual methodology, accounting for distance to roads, rivers, major cities and altitude, slope and annual rainfall. The assessment was independently conducted for two different time periods, 1990–2000 and 2000–2010, and for Madagascar's three major forest types. We found that PAs were effective to some extent in reducing deforestation and that some of this decrease can be attributed to the presence of PAs, not just to the confounding factors rendering the land assigned for protection less likely to be deforested. We found differences in PA effectiveness between the two time periods, and in general lower deforestation in the later time period has meant that the PAs have less pressures to resist. However, in the spiny forest, even if deforestation had overall diminished, the pressure on reference areas used to compare PAs seemed to have increased showing that PAs have indeed a mitigation effect and thus increased in effectiveness in the second time period. Our study highlights the alarming trend of what happens once enough forest has been lost in easily accessible areas and the pressures starts to spread to also more remote areas and lands comparable to PAs (remote and inaccessible).

The impact of natural resource use on bird and reptile communities within multiple-use protected areas: evidence from sub-arid Southern Madagascar

Multiple-use protected areas, in which sustainable levels of extractive livelihood activities are permitted, play an increasingly important role in the global protected area estate, and are expected to rise in prevalence. However, we know little about their effectiveness at conserving biodiversity. We surveyed bird and reptile communities in three areas across a forest disturbance gradient resulting from charcoal production and shifting cultivation within a multiple-use protected area in Madagascar’s sub-arid spiny forest. We scored individual species using a Conservation Value Index (CVI; a simple metric based on rarity, threat and distinctiveness), and estimated the total conservation value of each treatment by calculating the sum of frequency-weighted CVI scores across all present species. Bird and reptile community responses to forest disturbance were idiosyncratic. Bird richness was greatest in the moderate-disturbance treatment, but the low-disturbance treatment had the superior conservation value due to higher frequencies of locally-endemic species. Reptile richness was the same in low- and moderate-disturbance treatments, but the conservation value of the latter was greater. The high-disturbance areas had lowest richness and conservation value for both groups. For birds, increasing disturbance levels were accompanied by community turnover from high-value to low-value species, a pattern highlighted by CVI that is masked by assessing species richness alone. Although some endemic species appear to be resilient to degradation, multiple-use protected areas in Madagascar may lose biodiversity since most endemic species are forest-dependent. Stricter protected area models may be more appropriate in areas where much of the high-value biodiversity is sensitive to habitat degradation.

Tooth wear patterns in black rats (Rattus rattus) of Madagascar differ more in relation to human impact than to differences in natural habitats.

Dietary characteristics and environmental variables are important selective factors directing ecological diversification in rodents. On Madagascar, the introductions and spread of the commensal black rat (Rattus rattus) can be seen as example cases to study dietary niche occupation and dietary adaptation in an insular environment. We investigate how tooth wear as a measure of dietary adaptation of black rats differs between four distinct habitats (village, manioc fields, spiny forest, and rainforest) with different dietary resources. We use the 3D surface texture analysis (3DST, using 30 parameters according to ISO 25178) as a measure of dietary abrasiveness. 3DST is applied on the occlusal surface of the upper first molar of 37 black rat specimens. The rainforest sample displays less rough and less voluminous surface textures compared to the village samples as indicated by smaller values for height parameters (Sa, Sp, Sq), inverse areal material ratio (Smc), and volume parameters (Vm, Vmc, Vmp, Vv, and Vvc). We therefore rank sampling areas from highest to lowest abrasiveness (village>manioc fields/spiny forest>rainforest). The rats from villages and rainforest differ to such an extent that one could have interpreted them to belong to different species. This indicates a high degree of variability in terms of ingesta abrasiveness. Furthermore, the pronounced difference between rats from human habitations compared to rats from associated fields or natural vegetation is interpreted to clearly indicate shifts in dietary niche occupation in relation to human impact.

A landscape vulnerability framework for identifying integrated conservation and adaptation pathways to climate change: the case of Madagascar’s spiny forest

Context Integrated conservation decision-making frameworks that help to design or adjust practices that are cognisant of environmental change and adaptation are urgently needed.

Modelling the distribution of four Dioscorea species on the Mahafaly Plateau of south-western Madagascar using biotic and abiotic variables

Wild yam species (Dioscorea spp.) provide important supplementary food and thus contribute directly to the livelihood and well-being of local people in SW Madagascar. Given the ongoing exploitation of this resource, there is a necessity to identify and predict yam species distribution along environmental gradients to improve our understanding of sustainable management of this resource. Therefore, the aims of the current study were to identify predictors for the distribution of important wild yam species and to spatially predict their availability. To this end species abundance and environmental variables were collected in the field using a systematic sampling approach within a yams collection area of four villages (58 plots). A redundancy analysis (RDA) was conducted to investigate the relationship between wild yam species and 12 environmental variables. Species distribution models and species response curves were established for the most abundant wild yam species using nonparametric multiplicative regression (NPMR). These models were subsequently used in conjunction with geospatial data for predictive mapping. RDA depicted a clear pattern of species habitats with D. alatipes occurring in dry spiny forests on calcareous soils at remote places, while D. bemandry and D. fandra were found in forest habitats on sandy soils with high harvest intensities. The NPMR models explained 88% (D. alatipes), 82% (D. bemandry) and 37% (D. fandra) of the variation in species abundance. Sensitivity analysis indicated the importance of vegetation structure, human interventions, and soil characteristics in determining wild yam distribution. Predicted distribution maps showed that the population of wild yam is scarce and mostly located in restricted areas of open spiny forests and dry spiny forest thickets, where harvest intensity is high. This study highlights the need for long-term assessment and public awareness actions on yam harvest practices as well as the importance of anthropogenic factors for the distribution of yam as a key forest resource in SW Madagascar.

Reproductive Female Feeding Strategies in Spiny Forest-Dwelling Lemur catta in Southern and Southwestern Madagascar: How Do Females Meet the Challenges of Reproduction in this Harsh Habitat?

The spiny forest ecoregion of southern and southwestern Madagascar is characterized by low annual rainfall, high temperatures, short-stature xeric vegetation and lack of canopy. Lemur catta is often the only diurnal primate persisting in this habitat. For reproductive females living in spiny forests, gestation and early-to-mid lactation periods occur during the dry season when food resources are limited. We conducted a between-site comparison of variables important to the feeding ecology of reproductive female L. catta inhabiting spiny forest at 3 sites: Berenty spiny forest (BSF), Cap Sainte-Marie (CSM) and Tsimanampesotse National Park (TNP). We hypothesize that the ability for pregnant and lactating females to adequately obtain plant foods high in protein, low in fiber and with a high water content is crucial to their survival and successful reproduction in spiny habitat. We found favorable or relatively equal protein-to-fiber ratios in plant foods most frequently consumed by reproductive females, and preferred foods contained high water content. Some overlap in preferred plant species at the 3 sites suggests important plant foods for reproductive females inhabiting spiny forests. We suggest that choosing foods high in protein, relatively low in fiber and with high water content are behavioral adaptations allowing female L. catta to reproduce and survive in this habitat.

Beyond the Gallery Forest: Contrasting Habitat and Diet in Lemur catta Troops at Bezà Mahafaly Special Reserve

Ring-tailed lemurs have been studied intensively in the Parcel 1 gallery forest of Bezà Mahafaly Special Reserve. Here, we report on lemur groups in a mixture of deciduous dry forest and spiny forest just 5 km to the west. Compared to Parcel 1, Parcel 2 (P2) has a lower density of Tamarindus indica, a major dietary plant species for gallery forest lemurs. Recent studies in drier habitats have called into question the association of lemur density and tamarind presence. In order to address this question, we measured forest structure and composition of plant plots between parcels and conducted lemur feeding observations. The trees and shrubs within the parcels did not differ in height or diameter at breast height, but the frequencies of plant species that were common between parcels were significantly different. Numbers of feeding observations on foods common to both parcels did not differ, but their relative rankings within parcels did. Frequencies of food plants corresponded to earlier reports of lemur population densities. However, we found that the ring-tailed lemur diet is a mixture of plants that are eaten in abundance regardless of frequency and those that are locally available. In terms of their reliance on Tamarindus, P2 animals appear intermediate between those in gallery forests and nontamarind sites.

Ring-Tailed Lemur (Lemur catta) Health Parameters across Two Habitats with Varied Levels of Human Disturbance at the Bezà Mahafaly Special Reserve, Madagascar

The health of 36 wild, free-ranging ring-tailed lemurs (Lemur catta) at the Bezà Mahafaly Special Reserve was assessed across 2 habitats of varied human impact: a reserve riverine gallery forest, and a degraded mixed dry deciduous and Alluaudia-dominated spiny forest. While there were no statistically significant differences in leukocyte count or differential between habitats, female lemurs in the reserve gallery forest had significantly higher percentages of monocytes and eosinophils than male lemurs in the gallery forest. Lemurs from the degraded spiny habitat had significantly higher mean packed cell volume, hematocrit, hemoglobin, total protein, blood urea nitrogen, chloride, ionized calcium and urine specific gravity than lemurs from the reserve gallery forest. These findings may reflect lower hydration levels in lemurs living in degraded habitat, providing evidence that environmental degradation has identifiable impacts on the physiology and health of wild, free-ranging ring-tailed lemurs living in nearby habitats. Given the greater evidence of human impact in the mixed dry deciduous/spiny forest habitat, a pattern seen throughout southern Madagascar, biomedical markers suggestive of decreased hydration can provide empirical data to inform new conservation policies facilitating the long-term survival of this lemur community.

Torpor is not the only option: seasonal variations of the thermoneutral zone in a small primate

The reddish-gray mouse lemur (Microcebus griseorufus) is one of only a few small mammals inhabiting the spiny forest of southwestern Madagascar. In this study we investigated the physiological adjustments which allow these small primates to persist under the challenging climatic conditions of their habitat. To this end we measured energy expenditure (metabolic rate) and body temperature of 24 naturally acclimatized mouse lemurs, kept in outdoor enclosures, during different seasons (summer, winter, and the transition period between the two seasons). Mouse lemurs displayed two main physiological strategies to compensate seasonal and diurnal fluctuations of ambient temperature. On the one hand, individuals entered hypometabolism with decreasing ambient temperature (T a) during the transition period and winter, enabling them to save up to 21 % energy per day (92 % per hour) compared with the normal resting metabolic rate at comparable T a. On the other hand, euthermic mouse lemurs also showed physiological adjustments to seasonality when resting: the lower critical temperature of the thermoneutral zone decreased from summer to winter by 7.5 °C, which allowed mouse lemurs to keep energy demands constant despite colder T as during winter. In addition, the basal metabolic rate was substantially lowered prior to the winter period, which facilitated accumulation of fat reserves. The combination of physiological modifications during euthermia in addition to hypometabolism, which can be individually adjusted according to external parameters and respective body condition, is important as it allows M. griseorufus to cope with the environmental variability of an energetically challenging habitat.

Competition for food in a solitarily foraging folivorous primate (Lepilemur leucopus)?

Group-living folivorous primates can experience competition for food, and feeding competition has also been documented for solitarily foraging gummivorous and omnivorous primates. However, little is known about the types and consequences of feeding competition in solitary folivorous foragers. We conducted this study in the spiny forest of Berenty Reserve, southern Madagascar, to characterize the competitive regime of the nocturnal solitarily foraging white-footed sportive lemur (Lepilemur leucopus), a species that lives in dispersed pairs. We analyzed 1,213 hr of behavioral observations recorded simultaneously for the male and female of each of seven social units and recorded seasonal changes in food availability over a complete annual cycle. Lepilemur leucopus exhibited low selectivity in its dietary choice and mainly included the most abundant plant species in its diet. Contrary to our predictions, we did not find evidence for increased rates of contest (i.e., displacement from food trees) or scramble competition (i.e., shared use of food patches) during the lean season, neither within nor between social units. Instead, conflict rates were low throughout the year, and, during these observations, any feeding stress may have been more related to food quality than quantity. The resource defense hypotheses may not explain pair-living in this species as there was no indication that males defend food resources for their female pair-partners. The observed lack of feeding competition may indicate that a cryptic anti-predator strategy is a better predictor of spatial avoidance of pair-partners than conflict over food. While anti-predator benefits of crypsis may explain, at least partly, female-female avoidance, studies on the relationship between territory size/quality and reproductive success are required to understand whether feeding competition reduces the potential for female association in L. leucopus.

Limestone cliff - face and cave use by wild ring-tailed lemurs (<i>Lemur catta</i>) in southwestern Madagascar

Ring - tailed lemurs live in a range of habitats in southwestern Madagascar. To date, much of the knowledge of ring - tailed lemur ecology, biology and behavior come from riverine gallery forests sites. Recent years have seen an expansion of comprehensive research on this resilient species, including areas of limestone spiny forest along Madagascar’s southwestern coast. This work is documenting newly discovered behaviors by this species. The regular use of cliff - faces and embedded crevices and caves by ring - tailed lemurs in southwestern Madagascar are reported here. Cave use by several anthropoid primates has been explained as a thermoregulatory behavior. It is suggested that cliff - face and cave use by these ring-tailed lemurs serves several purposes, including resource acquisition, thermoregulation, and as an anti - predator avoidance strategy in the absence of suitable large sleeping trees. Observations indicate that the limestone boundaries of the Mahafaly Plateau and their associated xerophytic scrub forests warrant further conservation attention, given the presence of behavioral variation and increasing threats to this endangered primate species.

Defining the Low End of Primate Social Complexity: The Social Organization of the Nocturnal White-Footed Sportive Lemur (Lepilemur leucopus).

Whereas other species of sportive lemurs (genus Lepilemur) have been described as living in dispersed pairs, which are characterized by spatial overlap but a lack of affinity or affiliation between one adult male and female, existing reports on the social organization of the white-footed sportive lemur (Lepilemur leucopus) are conflicting, describing them as either living in dispersed one-male multifemale systems or pairs. We conducted this study in the spiny forest of Berenty Reserve, southern Madagascar, to clarify the social organization and to characterize the level of social complexity of this species. We combined 1530 h of radio-telemetry and behavioral observations over a period of 1 yr to describe the spatiotemporal stability, size, and interindividual overlap of individual home ranges as well as interindividual cohesiveness. Results revealed low intra- and high intersexual home range overlap. Although most of the social units identified consisted of dispersed pairs (N = 5), males were associated with two adult females in two cases. Furthermore, members of a social unit were never observed to groom each other or to share a daytime sleeping site, and Hutchinson’s and Doncaster’s dynamic interaction tests indicated active avoidance between pair partners. Low cohesiveness together with extremely low rates of social interactions therefore arguably places Lepilemur leucopus at the low end of primate social complexity.