Effects Of Forest Fragmentation Research Articles

Habitat fragmentation differentially shapes neutral and immune gene variation in a tropical bird species.

Habitat fragmentation is a major cause of biodiversity loss, responsible for an alteration of intraspecific patterns of neutral genetic diversity and structure. Although neutral genetic variation can be informative for demographic inferences, it may be a poor predictor of adaptive genetic diversity and thus of the consequences of habitat fragmentation on selective evolutionary processes. In this context, we contrasted patterns of genetic diversity and structure of neutral loci (microsatellites) and immune genes (i.e., toll-like receptors) in an understorey bird species, the wedge-billed woodcreeper Glyphorynchus spirurus. The objectives were (1) to investigate forest fragmentation effects on population genetic diversity, (2) to disentangle the relative role of demography (genetic drift and migration) and selection, and (3) to assess whether immunogenetic patterns could be associated with variation of ectoparasite (i.e., ticks) pressures. Our results revealed an erosion of neutral genetic diversity and a substantial genetic differentiation among fragmented populations, resulting from a decrease in landscape connectivity and leading to the divergence of distinct genetic pools at a small spatial scale. Patterns of genetic diversity observed for TLR4 and TLR5 were concordant with neutral genetic patterns, whereas those observed for TLR3 and TLR21 were discordant. This result underlines that the dominant evolutionary force shaping immunogenetic diversity (genetic drift vs. selection) may be different depending on loci considered. Finally, tick prevalence was higher in fragmented environments. We discussed the hypothesis that pathogen selective pressures may contribute to maintain adaptive genetic diversity despite the negative demographic effect of habitat fragmentation on neutral genetic diversity.

Forest fragmentation modifies the composition of bumblebee communities and modulates their trophic and competitive interactions for pollination

Understanding the effects of landscape fragmentation on global bumblebee declines requires going beyond estimates of abundance and richness and evaluating changes in community composition and trophic and competitive interactions. We studied the effects of forest fragmentation in a Scandinavian landscape that combines temperate forests and croplands. For that, we evaluated how forest fragmentation features (patch size, isolation and shape complexity, percentage of forest in the surroundings) as well as local flowering communities influenced bumblebee abundance, richness and community composition in 24 forest patches along a fragmentation gradient. In addition, we assessed the effect of fragmentation on bumblebee–plant network specialization (H2′), and potential inter- and intraspecific competition via shared plants. Patch isolation was associated with lower bumblebee abundance, whereas flower density was positively related to both bumblebee abundance and richness. Overall, forest fragmentation reduced the abundance of forest-specialists while increasing the abundance of open-habitat species. Patches with complex shapes and few flowers showed more generalized bumblebee–plant networks (i.e., fewer specific interactions). Patch shape complexity and the percentage of forest also modified inter- and intraspecific competitive interactions, with habitat generalists outcompeting forest specialists in fragmented areas. Understanding these mechanisms is necessary to anticipate to the impact of forest fragmentation on bumblebee decline.

Investigating the direct and indirect effects of forest fragmentation on plant functional diversity.

Ongoing habitat loss and fragmentation alter the functional diversity of forests. Generalising the magnitude of change in functional diversity of fragmented landscapes and its drivers is challenging because of the multiple scales at which landscape fragmentation takes place. Here we propose a multi-scale approach to determine whether fragmentation processes at the local and landscape scales are reducing functional diversity of trees in the East Usambara Mountains, Tanzania. We employ a structural equation modelling approach using five key plant traits (seed length, dispersal mode, shade tolerance, maximum tree height, and wood density) to better understand the functional responses of trees to fragmentation at multiple scales. Our results suggest both direct and indirect effects of forest fragmentation on tree functional richness, evenness and divergence. A reduction in fragment area appears to exacerbate the negative effects resulting from an increased amount of edge habitat and loss of shape complexity, further reducing richness and evenness of traits related to resource acquisition and favouring tree species with fast growth. As anthropogenic disturbances affect forests around the world, we advocate to include the direct and indirect effects of forest fragmentation processes to gain a better understanding of shifts in functional diversity that can inform future management efforts.

Effects of forest fragmentation on terrestrial macro-snail populations

Forest fragmentation is an increasing commonality with the continued rise in the extractive industries and various anthropogenic disturbances. While research has discovered negative effects of fragmentation such as ecotones, the impact on specific organisms is unknown. Sites were selected in a forest that has been fragmented for 25+ years, one fragmented within the past 10 years, and a primarily undisturbed forest (control) to assess macro-snail populations as well as additional environmental parameters. Preliminary data suggests differences in both snail abundance and diversity among the sites sampled. The newly fragmented site had the most snails present (n = 126) in comparison to both the control (n = 99) and the oldest fragmented site (n = 5). The older fragment had significantly less snails than both the recent fragment and control site. Even though the recent fragment had the highest snail abundance, only 31% were live specimens compared to 44% at the control site. Diversity at the control site was twice as high as the recent fragment in which 85% of specimens collected consisted of the same genera. While this is just a trial run, we can hypothesize from this preliminary data that diversity of terrestrial macro-snails declines with time since fragmentation and may ultimately lead to extirpation. Additional sites will be sampled in the near future to further investigate the impacts of fragmentation on snail abundance and diversity.

Avian responses to forest fragmentation during the breeding and non‐breeding seasons

Forest fragmentation represents a threat to several bird species worldwide. Several factors can change across seasons (e.g. bird perception of the landscape, weather conditions, biotic interactions), which can modify the response of bird populations to forest fragmentation. However, most studies have been conducted only during the breeding season. Here we assessed the relationship between forest fragmentation (patch area and patch isolation) with population abundances of resident species during both the breeding and the non‐breeding seasons. Bird population abundances (all species in the community, subsets of forest and habitat generalist species and for individual species) were estimated across a gradient of area‐isolation in a semi‐arid forest in Cordoba, Argentina. Population abundance of the overall avian community and of the subset of forest species declined with patch area reduction independently of the season. By contrast, the subset of habitat generalist species was not affected by patch area reduction or by the increase in patch isolation, either during the breeding or during the non‐breeding season. When the analyses were carried out for individual species, we found four forest species and one habitat generalist species whose responses (the relationship between population abundance and patch area or with isolation) were different between breeding and non‐breeding seasons. The negative effects of forest fragmentation were found mainly during the breeding season. Our results suggest that reduction of patch area may lead to a reduction of more than 65% of the population abundance of forest bird species, during both the breeding and the non‐breeding season. Therefore, there is an urgent need to conserve large forest patches within the region as irreplaceable elements for the conservation of populations of several species.

Isolation and characterization of microsatellite loci in Astroniumgraveolens (Anacardiaceae) and cross amplification in related species.

Microsatellite markers are a useful genetic tool to answer ecological and conservation genetics questions. Microsatellite primers were developed and characterized to evaluate forest fragmentation effects on genetic structure, diversity and gene flow patterns in the dioecious tropical tree Astroniumgraveolens (Anacardiaceae). Using genomic library enrichment, sixteen microsatellite loci were developed for A.graveolens. Polymorphism was evaluated in 80 individuals from four localities in Mexico. The overall number of alleles detected was 63, average alleles per locus 3.9 with a range from one to 11 per locus. Cross amplification trails on related species in the Anacardiaceae family: Spondiaspurpurea and Amphipterygiumadstringens, achieved successful amplification for all primers. Microsatellite markers described here are the first to be characterized for A.graveolens. These genetic markers will be a useful tool to assess the genetic consequences of habitat fragmentation and selective logging on A.graveolens populations. Cross amplification success on S.purpureaandA.adstringens suggest that they may be used for population genetic studies in other species within the family.

Habitat fragmentation influences genetic diversity and differentiation: Fine-scale population structure of Cercis canadensis (eastern redbud).

Forest fragmentation may negatively affect plants through reduced genetic diversity and increased population structure due to habitat isolation, decreased population size, and disturbance of pollen‐seed dispersal mechanisms. However, in the case of tree species, effective pollen‐seed dispersal, mating system, and ecological dynamics may help the species overcome the negative effect of forest fragmentation. A fine‐scale population genetics study can shed light on the postfragmentation genetic diversity and structure of a species. Here, we present the genetic diversity and population structure of Cercis canadensis L. (eastern redbud) wild populations on a fine scale within fragmented areas centered around the borders of Georgia–Tennessee, USA. We hypothesized high genetic diversity among the collections of C. canadensis distributed across smaller geographical ranges. Fifteen microsatellite loci were used to genotype 172 individuals from 18 unmanaged and naturally occurring collection sites. Our results indicated presence of population structure, overall high genetic diversity (H E = 0.63, H O = 0.34), and moderate genetic differentiation (F ST = 0.14) among the collection sites. Two major genetic clusters within the smaller geographical distribution were revealed by STRUCTURE. Our data suggest that native C. canadensis populations in the fragmented area around the Georgia–Tennessee border were able to maintain high levels of genetic diversity, despite the presence of considerable spatial genetic structure. As habitat isolation may negatively affect gene flow of outcrossing species across time, consequences of habitat fragmentation should be regularly monitored for this and other forest species. This study also has important implications for habitat management efforts and future breeding programs.

Effects of forest fragmentation on the lekking behavior of White‐throated Manakins in Central Amazonia

Effects of forest fragmentation on the lekking behavior of White‐throated Manakins in Central Amazonia

Effects of Forest Fragmentation on Feather Corticosterone Levels in an Amazonian Avian Community

In the Amazon, the construction of hydroelectric dams is an emergent driver of biodiversity loss, creating numerous land-bridge islands, most of them unable to sustain an assemblage of bird species comparable to the intact forest. Although we understand the effects of forest fragmentation on species richness and distribution, we still need to uncover the physiological mechanisms underlying the success of organisms living in disturbed habitats. In this study, we used feather corticosterone levels as a measurement of physiological indicators of stress, evaluating whether corticosterone levels mirror the effects of habitat fragmentation on species occurrence. Since data suggest that smaller islands can reduce habitat suitability, increasing stress in birds that live within them, we predicted that birds living in smaller islands would present increased feather corticosterone levels. We captured birds in 13 islands of varying size and in two continuous forests and analysed feather corticosterone levels of 265 individuals from eight different species. Overall, our findings did not support the hypothesis that corticosterone varies in relation to island size, except for the Guianan Antwarbler Hypocnemis cantator, which presented the predicted pattern: decreasing feather corticosterone levels with increasing island size. These differences suggest that species respond differently to stressors driven by fragmentation. Further studies are necessary to assess the reliability of corticosterone levels as a physiological measurement of stress and to determine which parameters are useful to understand how insularisation caused by human activities may influence the resistance of avian populations to habitat disturbances. —Bicudo, T., Anciaes, M., Arregui, L. & Gil, D. (2020). Effects of forest fragmentation on feather corticosterone levels in an Amazonian avian community. Ardeola, 67: 229-245.

Effects of habitat-patch size and patch isolation on the diversity of forest birds in the urban-forest mosaic of Durban, South Africa

Loss of habitat area and structural heterogeneity through anthropogenic fragmentation poses a threat to the survival of wildlife, which may be exacerbated by urban pressures. Understanding the underlying ecological processes that influence species’ persistence in fragmented landscapes is vital for conservation. We described the effects of forest fragmentation via measures of patch size and isolation on the taxonomic richness and functional richness of forest bird communities in five Protected Areas within the urban-forest mosaic of the Durban Metropolitan Area, South Africa. We conducted 137 fixed-radius point-count surveys across 41 distinct forest patches during the austral breeding season. We quantified the avian taxonomic, guild and functional richness and measured at each survey patch. We measured the influence of patch size, Euclidean isolation distance, patch shape and habitat configuration (i.e. habitat amount) on each diversity measure. We then conducted a series of General Linear Models to determine how fragmentation and patch configuration influenced the diversity of forest birds. The explanatory variables in the top models had a significant effect on all avian diversity measures but habitat amount did not. The amount of habitat surrounding a patch was not significant for measures of bird diversity but based on the Akaike’s weight it was important for specialist species. Isolation distance did not have a significant effect on the measures of bird diversity. An increase in patch shape index increased species richness. These results show the importance of large forest fragments/patches for the conservation of forest birds and for maintaining ecosystem functioning and services of forests in increasingly urbanising landscapes, to the benefit of the environment and its human population.

Land-use and coverage in the structure of the landscape in a Tropical Dry Forest in northeast Brazil

Landscape Ecology using GIS is applied to understand the effects of forest fragmentation and makes it feasible mainly for extensive areas, through the possibility of analyzing both the variety of units that compose it in time. This study aims to analyze the land use and coverage of tropical dry forests and to characterize their landscape structure in an area of the municipality of Floresta, Pernambuco, Brazil, in order to understand how the landscape configuration can influence the conservation. Orbital images were used from LANDSAT, and the classification was performed in the QGIS 2.18 software using the Maximum Likelihood methodification, for the years of 2007 and 2017. A circular buffer was incorporated around the area of study to analyze the structural patterns in the context of the landscape. Five thematic classes were used: dense vegetation, sparse vegetation, exposed soil, grassland, and water. The metrics were obtained through the Patch Analyst tool only to the class of dense vegetation. It is noted that much of the dense vegetation has become sparse. There was a reduction of exposed soil and an increase in grassland areas, which may indicate a regeneration process of the vegetation. The fragments of dense vegetation with more substantial dimensions are on constant exploratory actions and are the most affected with the reduction of size. Furthermore, climatic factors, periods of drought, and the presence of livestock may also affect the fragmentation of dense vegetation patches. Therefore, the landscape became heterogeneous, and a tendency was observed to increase the fragmentation, mainly in the more significant spots.

Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.

Fragmentation reduces severe drought impacts on tree functioning in holm oak forests

Fragmentation and increased summer drought are two main threats to Mediterranean forests. Forest fragmentation has many negative impacts on forests but could attenuate water stress on Mediterranean species by reducing intraspecific competition or improving soil properties at forest edges. However, little is known about the combined effects of drought and fragmentation on tree functioning. We evaluated the effect of forest fragmentation on tree functioning under severe drought periods in continental holm oak forests (Quercus ilex). We monitored the functional response of focal trees before and during summer drought in two regions of the Iberian Peninsula with contrasting climates. Forest interiors, edges and small forest fragments were compared. Predawn leaf water potential (Ψpd), leaf stomatal conductance to water vapor (gs), maximum leaf photochemical efficiency (Fv/Fm), ground (Fo) and maximum (Fm) fluorescence in dark adapted, fully-developed leaves were assessed in the field. Trees located at forest interiors and edges showed strong stomatal closure and clear symptoms of photochemical inhibition, revealing that the trees were operating at predawn water potential beyond tolerance thresholds. In contrast, trees located in small forest fragments were able to maintain high levels of functionality for all ecophysiological parameters during the drought. These differences in tree functioning among fragments were more noticiable in the driest region. Our results prove that forest fragmentation attenuates drought impacts on tree functioning, and that these positive effects become more important during extremely dry periods. These novel findings are essential for realistic predictions of the functionality of fragmented forests under increasing and more severe droughts.

Ecoacoustics of small forest patches in agricultural landscapes: acoustic diversity and bird richness increase with patch size

ABSTRACT The species–area relationship is well documented across species in multiple ecosystems, and as such is widely accepted as one of ecology’s key patterns. Although acoustic diversity has generally been correlated with species richness, the response of acoustic diversity to habitat size is unknown. Thus, we tested the transferability of the species–area relationship to a broader ‘biodiversity–area relationship’, investigating if acoustic diversity increases with habitat size. Twenty-two forest patches of increasing size (0.01–4.7 ha) in an agricultural area were inventoried for structural characteristics and bird richness. Plots were acoustically monitored over three time periods. Acoustic diversity values were related to habitat size, vegetation structural diversity and bird richness using linear regression analysis. We confirmed that acoustic diversity increased with forest patch size. When tested in separate models, bird richness and forest structural parameters explained variations in acoustic diversity equally well as forest patch size. Although the relative effects of patch size, bird richness and habitat heterogeneity are difficult to disentangle, acoustic diversity can be a useful proxy to study effects of forest fragmentation as it is subjected to a similar combination of drivers as traditionally surveyed metrics of biodiversity. Key policy insights This study provides evidence that indices on acoustic diversity relate to vocalizing species diversity and forest structure, making these indices a useful tool to study biodiversity processes. This study confirms that decreasing habitat size correlates with decreasing biodiversity, for the first time including acoustic diversity as one aspect of biodiversity. This study underlines the importance of preserving forest patches in agricultural landscapes as refuges for biodiversity. Biodiversity can be enhanced by increasing forest patch size, reducing fragmentation and increasing habitat quality through enhancing structural diversity.

The genetic consequences of habitat specificity for fig trees in southern African fragmented forests

Theory predicts that fragmentation will lead to reduced gene flow between populations, with loss of genetic diversity and increased population differentiation. However, these predictions may not always hold true, especially for long-lived woody plants and some fig trees (Ficus species) may not be affected by fragmentation because their fig wasps can transfer pollen for distances of over 100 km. Here we contrast the extent of genetic isolation caused by fragmentation among three southern African Ficus species with different habitat dependencies and distributional ranges. Two of the species are restricted to forest environments, which have been fragmented since at least the Pleistocene, and provide an indication of the long-term genetic effects of forest fragmentation. The third species is less forest-dependent, with a more general habitat association and more continuous populations. We found significant population differentiation in all three species. Populations of F. bizanae, a forest specialist with a highly restricted distribution, displayed the most genetic structure, followed by the second forest specialist, F. craterostoma. Populations of the habitat-generalist F. sur were the least genetically structured. Forest specialist Ficus species are clearly not immune to habitat fragmentation, despite extensive pollen flow, and other southern African forest trees are likely to have experienced similar or greater effects of habitat fragmentation. The strong genetic structure of F. bizanae suggests a limited seed dispersal range and local dispersal by the fig wasp pollinator, a possible adaptation to the limited range of its host fig tree.

Contrasting effects of host tree isolation on population connectedness in two tropical epiphytic bromeliads.

Conversion of primary forests to pastures is a major cause of habitat fragmentation in the tropics. Fragmentation is expected to impede gene flow for many plant species that are restricted to remaining forest fragments. Epiphytes may be especially vulnerable to this effect of forest fragmentation because they depend on host trees. However, trees that remain in pastures may enhance connectivity across the landscape for epiphyte species that can thrive on such trees. To investigate this possibility, we studied the genetic structures of two such species on isolated pasture trees and surrounding forest, in relation to their local abundances in different habitat types and aspects of their reproductive biology including pollen and seed dispersal agents, and looked for evidence of increased or diminished gene flow. We used microsatellite markers to assess geographic patterns of genetic diversity and differentiation in two epiphytic bromeliads, Catopsis nitida and Werauhia tonduziana, in the Monteverde region of Costa Rica. About 85% of the FST value for Catopsis nitida was found among pastures within regions, while for Weruahia tonduziana, about 80% of the FST value was contributed by differences between regions, indicating much more gene flow within regions, relative to C. nitida. Although there was substantial genetic differentiation among epiphyte populations, those on isolated pasture trees were not substantially less diverse than those in adjacent forests, suggesting that pasture trees may serve as "stepping stones" that help these species maintain their genetic connectedness and diversity at larger geographic scales.

Soil Carbon Storage and Its Determinants in Forest Fragments of Differentiated Patch Size

Research Highlights: Soil carbon storage (SOC) decreased due to forest fragmentation through lower proportion of macroaggregate distribution, higher storage of fine roots and litter falls, and lower fine root production rate. Background and Objectives: Globally, forest fragmentation processes lead to enormous losses of SOC in forests. We investigated SOC and its determinants in forest fragments experiencing edge disturbances in south China. Materials and Methods: Soil aggregate characteristics, dynamics of fine roots, and litter fall were studied from forest edges to interiors. Generalized linear mixed models were used to model the contributions of fine root and litter fall dynamics to carbon concentration in aggregates. Results: Large and small macroaggregates had higher proportion of aggregate distribution and contributed more carbon to SOC in all types of plots in the present study. SOC significantly increased from forest edges to interiors due to carbon concentration of these two aggregate types increasing from edges to interiors, while the proportion of different aggregate distributions was similar within each plot. The same trend was found with increasing forest patch size. Fine root biomass storage had the strongest impact on carbon concentration in large macroaggregates and microaggregates, with higher fine root biomass storage associated with lower carbon concentration. In addition, biomass storage and production rates of both fine roots and litter falls decreased from forest interiors to edges. Our results showed that SOC was significantly decreased due to the lower proportion of large and small macroaggregate distribution, and lower fine root production rate in forest fragments. Conclusions: SOC loss due to effects of forest fragmentation and forest edges occurred through decreased concentrations of soil aggregates and fine root production rates. Results from this study will enhance our ability to evaluate soil aggregate, fine root, and leaf litter fall contributions to SOC within forest fragments, and to suggest basic recommendations for the management and conservation of these forest fragments.

Variation in soil and foliar nutrition status along a forest edge–interior gradient in sugar maple forest fragments

The consequences of forest fragmentation and edge effects on soil nutrient availability and nutrition of sugar maple (Acer saccharum Marsh.) forests remain understudied. We assessed soil chemistry (bulk pH, total carbon (C) and nitrogen (N), extractable phosphorus (P), exchangeable cations, and mineralizable N) and foliar nutrition (N, P, potassium (K), calcium (Ca), and magnesium (Mg)) of mature sugar maple forests along an edge–interior gradient (10, 20, 30, 50, 70, and 120 m from the forest edges) in seven sugar maple forest stands (three on sandstone and four on dolomite bedrock) that are embedded within an agricultural landscape in southern Quebec, Canada. We hypothesized that foliar nutritional imbalances of sugar maple forests would decline along this gradient. Foliar nutrition was analyzed using the diagnosis and recommendation integrated system (DRIS) and the compositional nutrient diagnosis with isometric log-ratio (CND-ilr) method. At the sandstone sites, rates of N mineralization and nitrification increased with increasing distance from the forest edge. Other soil chemical properties and all sugar maple foliar indices of nutritional diagnostics varied weakly along the edge–interior gradient. Assessment of sugar maple forest nutritional status through different nutritional indices revealed K and P deficiencies in all stands that were sampled and at all distances from the forest edge. Overall, we found weak forest-edge effects on soil chemical properties and sugar maple forest nutritional status.

2019 Julie S Denslow & Peter Ashton Prizes for the Outstanding Articles Published in Biotropica

2019 Julie S Denslow &amp; Peter Ashton Prizes for the Outstanding Articles Published in <i>Biotropica</i>

Ecological fragmentation effects in mouse lemurs and small mammals in northwestern Madagascar.

Habitat loss and fragmentation are major ecological forces threatening animal communities across the globe. These issues are especially true in Madagascar, where forest loss is ongoing. We examined the effects of forest fragmentation on the distribution and abundance of sympatric, endemic gray, and golden-brown mouse lemurs (Microcebus murinus and Microcebus ravelobensis), the endemic western tuft-tailed rat (Eliurus myoxinus), and the invasive black rat (Rattus rattus) in two regions in northwestern Madagascar. We used systematic capture procedures in 40 forest fragments and four continuous forest sites which differed in size, shape, and degree of isolation. With a trapping effort of 11,567 trap nights during two dry seasons (2017-2018), we captured 929 individuals (432 M. ravelobensis, 196 M. murinus, 116 E. myoxinus, and 185 R. rattus). We examined the influence of study region, forest type (fragment vs. continuous), forest size, forest shape, the proportion of 50-m forest edge and distance to continuous forest on the abundance and interaction of the four species. Responses to fragmentation differed strongly between species, but no interaction could be detected between the abundance of the different species. Thus competition within and between native and invasive species may not be regulating abundances in these regions. On the contrary, the abundance of M. ravelobensis and E. myoxinus differed significantly between study regions and was negatively affected by fragmentation. In contrast, there was no evidence of an impact of fragmentation on the abundance of M. murinus. Finally, the invasive R. rattus responded positively to the increasing distance to the continuous forest. In conclusion, the response of small Malagasy mammals to forest fragmentation varies largely between species, and fragmentation effects need to be examined at a species-specific level to fully understand their ecological dynamics and complexity.