Effects Of Forest Fragmentation Research Articles

Why do understorey Licuala palm fruits turn from red to white and then black when ripe?

Licuala ferruginea Becc., a tropical forest understorey palm, is observed to have fruits that appear red in colour when unripe, turning pink, then white, purple and finally black in colour as they ripen. We monitored 13 fruiting palms in rainforest fragments and recorded the consumption of fruits by animals via camera traps. We also documented the fruiting phenology of two palms in the nursery. In the rainforest fragments, a Cream-vented Bulbul (Pycnonotus simplex) was observed plucking a mature purple fruit from a L. ferruginea palm, before flying away with the fruit in its beak. This was the only bird that was observed feeding on the mature fruit. A range of mammals, dominated by edge species such as the Long-tailed Macaque and Wild Boar, were observed to consume L. ferruginea fruits indiscriminately across all five colour stages, thereby limiting the dispersal of the fruits. Forest bulbul gape sizes also matched the fruit size, suggesting that forest bulbuls are the likely dispersers of the palm in the original forest where edge species are not in high densities. We further posit that the initial phase of red fruits, with high contrasting red reflectance against a green foliage background, might be a form of early advertisement to birds. The fruit then turns pink and white, which have high green reflectance and is less contrasting, thereby reducing the conspicuity of the fruit. This allows the fruit to ripen with high fructose and glucose content, and turn purple and black, which are known visual cues for birds. This study provides indicative support for the dispersal syndrome hypothesis and highlights the potential effects of forest fragmentation on plant-frugivore interactions.

Forest fragmentation effects on mutualistic interactions: frugivorous birds and fruiting trees

While many effects of forest fragmentation are reasonably well understood, knowledge of interspecific interactions in fragmented ecosystems is much more limited, particularly for high diversity tropical forests. Using nearly 40 years of data from the Biological Dynamics of Forest Fragments Project in Central Amazonia, we assessed whether forest fragment area and time since isolation impact mutualistic interactions between frugivorous birds and their food resources. We used structural equation modeling to analyze the complex pathways between four main variables determining these interactions: fruiting tree abundance, frugivorous bird abundance, forest fragment area, and time since fragment isolation. Our results confirm that fragment area alters the abundance of some tree resources, with successional plant families increasing in abundance with decreasing fragment size. However, these changes do not drive alterations in the abundance of frugivorous birds. We also tested if bird species with a greater relative diet breadth are less vulnerable to forest fragmentation and found that specialist frugivores are more vulnerable to forest fragmentation immediately after isolation but are not differentially impacted within the long term. Collectively, our results demonstrate the need to further evaluate human‐driven habitat change across multiple timescales to fully understand its impacts on complex species interactions.

Effect of Forest Fragmentation on Fungal Diversity in Tropical Rainforests in Argentina

Effect of Forest Fragmentation on Fungal Diversity in Tropical Rainforests in Argentina

Lizard abundance in forest fragments: effects of patch size, patch shape, thermoregulation, and habitat quality

Abstract The effects of forest fragmentation on ecosystems are pervasive, but little is known about the factors that influence lizard abundance in fragmented landscapes. We studied the roles of patch size and shape, thermal quality, and refuge availability as predictors of the relative abundance of Psammodromus algirus lizards at deciduous or evergreen forest fragments surrounded by cereal fields. Relative abundance, based on time-controlled counts, decreased from the northeast (dominated by deciduous habitat) to the southwest (with a higher cover of croplands, and dominated by evergreen habitat). Refuge availability was correlated with this gradient, decreasing from the northeast to the southwest and being larger in deciduous than in evergreen fragments. After controlling for the effects of this environmental variation, lizard abundance increased as perimeter-to-area ratio (P/A) decreased (and consequently as fragment size increased). Although the effects of thermal quality as such were negligible, our results can be interpreted in the light of thermoregulatory requirements; given the low temperatures available at shaded locations, lizards should actively select sunlit patches while they try to minimize predation risk by basking as close as possible to the nearest refuge. Although use of fragment edges as basking sites is expected to increase with P/A ratio, lizards should avoid using them as basking sites, because both exposure to predators and risk of overheating are expected to be higher at edges and croplands than inside fragments. We conclude that long and narrow forest strips with high P/A ratios could act as ecological traps rather than as dispersion-promoting corridors.

Blind measurements did not confirm effects of forest fragmentation on fluctuating asymmetry of a tropical butterfly Morpho helenor

Re-evaluation of photographs of the tropical butterfly Morpho helenor from a previous study (Pignataro et al. 2023) revealed that its conclusion regarding increased wing fluctuating asymmetry in forest edge habitats compared to forest interior habitats could not be replicated. This discrepancy likely arises from (i) original measurements not being conducted blindly, (ii) insufficient photograph quality hindering accurate landmark selection, and (iii) a lack of detailed description of the measurement protocol. The likelihood of false positive discoveries within the published data concerning the impacts of environmental stress on the fluctuating asymmetry of plants and animals is probably higher than previously assumed.

A global meta-analysis of the impacts of forest fragmentation on biotic mutualisms and antagonisms.

Forest fragmentation is a grave threat to biodiversity. Forests are becoming increasingly fragmented with more than 70% now < 1km from forest edge. Although much is known about the effects of forest fragmentation on individual species, much less is understood about its effects on species interactions (i.e., mutualisms, antagonisms, etc.). In 2014, a previous meta-analysis assessed the impacts of forest fragmentation on different species interactions, across 82 studies. We pooled the previous data with data published in the last 10 years (combined total 104 studies and 168 effect sizes). We compared the new set of publications (22 studies and 32 effect sizes) with the old set to evaluate potential changes in species interactions over time given the global increase in fragmentation rates. Mutualisms were more negatively affected by forest fragmentation than antagonisms (p < 0.0001). Edge effects, fragment size, and degradation negatively affected mutualisms, but not antagonisms, a different finding from the original meta-analysis. Parasitic interactions increased as fragment size decreased (p < 0.0001)-an intriguing result at variance with earlier studies. New publications showed a more negative mean effect size of forest fragmentation on mutualisms than old publications. Although research is still limited for some interactions, we identified an important scientific trend: current research tends to focus on antagonisms. We concluded that forest fragmentation disrupts important species interactions and that this disruption has increased over time.

Effects of forest fragmentation on natural populations of Anadenanthera colubrina (Vell.) Brenan: Insights for conservation and sustainable management

Effects of forest fragmentation on natural populations of Anadenanthera colubrina (Vell.) Brenan: Insights for conservation and sustainable management

Effects of forest fragmentation on the dietary ecology and activity of a nocturnal lemur communityin North West Madagascar.

Deforestation and habitat fragmentation is the primary threat to primate populations. The primates that live within degraded and anthropogenically disturbed habitats typical of fragmented landscapes have to cope with lower availability of resources in comparison to primates in continuous, undisturbed forests. While some species are sensitive to forest fragmentation, some evidence exists to suggest that primates can alter their behavior and adapt to such changes, which enables their survival in suboptimal habitat. In this study, we assessed how forest fragmentation and its associated edge-effects impact the feeding ecology and activity levels of a nocturnal primate community in the Sahamalaza-Iles Radama National Park, North West Madagascar. From March 06, 2019 to May 17, 2022, we collected data on tree and invertebrate phenology at our study site, and feeding ecology and activity for 159 lemur individuals from four species. Fruit and flower availability varied significantly between continuous and fragmented forest, and between forest core and edge areas, with continuous forest exhibiting higher continuous fruit and flower availability. Lemur feeding ecology varied significantly too, as the feeding niches of all four species were significantly different between continuous and fragmented forest and between core and edge areas. However, lemur activity levels were mostly consistent among all forest areas. The results of this study suggest that nocturnal lemurs are able to adapt their dietary ecology in response to the available food sources within their habitat. Due to this flexible ecology and dietary plasticity, the lemurs do not need to significantly alter their behavior in different environments to fulfill their dietary needs. While nocturnal lemurs demonstrate adaptability and flexibility to degraded habitat, it is unclear how far this plasticity will stretch considering that Madagascar's forests are still being cleared at an alarming rate. Urgent conservation action is therefore needed to ensure the future of lemur habitat.

Effects of Forest Fragmentation on Connectivity and Genetic Diversity in an Endemic and an Invasive Rodent in Northwestern Madagascar.

Habitat loss and fragmentation are of concern to conservation biologists worldwide. However, not all organisms are affected equally by these processes; thus, it is important to study the effects of living in fragmented habitats on species that differ in lifestyle and habitat requirements. In this study, we examined the dispersal and connectivity patterns of rodents, one endemic (Eliurus myoxinus) and one invasive (Rattus rattus), in two landscapes containing forest fragments and adjacent continuous forest patches in northwestern Madagascar. We generated genetic (RADseq) data for 66 E. myoxinus and 81 R. rattus individuals to evaluate differences in genetic diversity as well as inbreeding and connectivity in two landscapes. We found higher levels of inbreeding and lower levels of genetic diversity in E. myoxinus compared with R. rattus. We observed related dyads both within and between habitat patches and positive spatial autocorrelation at lower distance classes for both species, with a stronger pattern of spatial autocorrelation in R. rattus. Across each site, we identified contrasting migration rates for each species, but these did not correspond to habitat-matrix dichotomies. The relatively low genetic diversity in the endemic E. myoxinus suggests ecological constraints that require further investigation.

Habitat suitability analysis in a natural peat swamp forest on Sumatran elephants using remote sensing and GIS

ContextIt is essential to assess the suitable habitat for elephants in order to mitigate the effects of forest fragmentation on conservation.AimsThis study aimed to estimate the potential suitable habitats for Sumatran elephants in the fragmented forest in the Padang Sugihan wildlife reserve area in southern Sumatra, Indonesia.MethodsThe habitat suitability was analyzed using some environmental factors such as slope, elevation, land cover, distance to rivers, and distance to agricultural areas. The remote sensing, geographic information system (GIS), and MaxEnt model were used to determine the potential habitat suitability for Sumatran elephants.ResultsThis study revealed areas of suitable habitat were evenly distributed throughout the study area, with the composition being suitable (45%), highly suitable (5%), and less suitable (50%). This study revealed the most suitable habitats were found in dense forest areas (gelam or Melaleuca cajuputi forest), which were highly affected by river adjacency, whereas agricultural areas resulted in constrained suitability and fragmentation of forested areas.ConclusionsAs a whole, the estimation of elephant habitat using remote sensing and GIS may guide the development of conservation strategies for elephant conservation in this region.

Intraspecific variation in sensitivity to habitat fragmentation is influenced by forest cover and distance to the range edge

The relative effects of habitat loss and fragmentation on biodiversity have been a topic of discussion for decades. While it is acknowledged that habitat amount can mediate the effects of habitat fragmentation, it is unclear what other factors may drive inter- and intraspecific variation in fragmentation effects and their implications for conservation. We tested whether the effects of forest fragmentation on 362 bird species' occurrence in the Atlantic Forest of Brazil are mediated by distance to geographic range edge and habitat amount, and whether these effects explain intraspecific variation across populations. Using a single binomial linear mixed effects model, we found that fragmentation had mostly negative effects on occurrence probability up to 1080 km from the species' range edge, independent of habitat amount. We also show that above this distance, fragmentation has predominantly positive effects, more accentuated in deforested landscapes. We demonstrate that fragmentation effects can be both positive and negative, indicating that different populations of the same species can respond differently depending on distance to range edge and local forest cover. Our results help clarify one of the drivers of contradictory results found in the fragmentation literature and highlight the importance of preventing habitat fragmentation for the conservation of endangered populations. Conservation initiatives should focus on minimising fragmentation closer to range edges of target species and in regions where species range edges overlap.

Effects of forest fragmentation on avian breeding activity.

Biodiversity declines and ecosystem decay follow forest fragmentation; initially, abundant species may become rare or be extirpated. Underlying mechanisms behind delayed extirpation of certain species following forest fragmentation are unknown. Species declines may be attributed to an inadequate number of breeding adults required to replace the population or decreased juvenile survival rate due to reduced recruitment or increased nest predation pressures. We used 10years of avian banding data, 5years before and 4 years after fragment isolation, from the Biological Dynamics of Forest Fragments Project, carried out near Manaus, Brazil, to investigate the breeding activity hypothesis that there is less breeding activity and fewer young after relative to before fragment isolation. We compared the capture rates of active breeding and young birds in 3 forest types (primary forest, fragment before isolation, and fragment after isolation) and the proportion of active breeding and young birds with all birds in each unique fragment type before and after isolation. We grouped all bird species by diet (insectivore or frugivore) and nesting strategy (open cup, cavity, or enclosed) to allow further comparisons among forest types. We found support for the breeding activity hypothesis in insectivorous and frugivorous birds (effect sizes 0.45 and 0.53, respectively) and in birds with open-cup and enclosed nesting strategies (effect sizes 0.56 and 0.44, respectively) such that on average there were more breeding birds in fragments before isolation relative to after isolation. A larger proportion of birds in the community were actively breeding before fragment isolation (72%) than after fragment isolation (11%). Unexpectedly, there was no significant decrease in the number of young birds after fragment isolation, although sample sizes for young were small (n=43). This may have been due to sustained immigration of young birds to fragments after isolation. Together, our results provide some of the strongest evidence to date that avian breeding activity decreases in response to fragment isolation, which could be a fundamental mechanism contributing to ecosystem decay.

Fragment size and isolation is associated with the presence of two forest owls in a fragmented environment in Central Argentina

In the semiarid Espinal ecoregion from central Argentina, deforestation has produced a large retraction of native forests and an accelerated process of fragmentation. Here we assess the effects of forest fragmentation within an agricultural matrix on the presence of two forest owls: the Ferruginous pygmy-owl (Glaucidium brasilianum) and the Tropical screech-owl (Megascops choliba). We searched for the species in fragments of different sizes and at different distances from large-continuous forest tracts. We detected one or both species at 43% of the 84 surveyed points. The Tropical Screech Owl was detected at 13 points, the Ferruginous Pygmy Owl was detected at 14 points, and both species were detected at 9 points. For the Ferruginous pygmy-owl, the area of the fragment where the point registration was made was the only variable associated with its presence. The model for Tropical Screech-Owl indicated that the variable that best explained its presence was the distance to the nearest forest fragment. For both species the association was negative. Our results suggest that despite being generalist and widely distributed species, both owls were negatively affected by the fragmentation process, highlighting the importance of the preservation of forest remnants and their connectivity.

Guild-dependent effects of forest fragmentation in canopy arthropod diversity associated to Quercus deserticola

Guild-dependent effects of forest fragmentation in canopy arthropod diversity associated to Quercus deserticola

Early Signs of the Effects of Forest Fragmentation on the Genetic Diversity and Structure of the Threatened Ecuadorian Tree Ocotea rotundata (Lauraceae)

The diversity of genetic resources is essential to cope with environmental changes. However, despite forests play a crucial role in mitigating changes, genetic knowledge has scarcely been used for forest conservation. In this study, we used nuclear microsatellites to understand the patterns of genetic diversity and population genetic structure in Ocotea rotundata van der Werff (Lauraceae), an endemic Ecuadorian tree, highly affected by habitat changes and fragmentation. Our results show high levels of genetic diversity, except in one population. The level of genetic differentiation between populations was low and genetic clusters showed no apparent spatial pattern. In fact, a high degree of genetic admixture was found between most populations. Migration rates were asymmetric but overall high, except in one population, where outgoing gene dispersal was limited. Nevertheless, allelic fixation values suggested a general deficit in heterozygotes, probably due to an increase in the levels of mating between close relatives. Although long-lived organisms, such as trees, can often accumulate a surprising amount of genetic diversity, the results found here could be an early sign of a decline in the diversity of O. rotundata. These findings provide baseline information on genetic resources to support future restoration programs to mitigate the impacts of changes in O. rotundata populations.

Structural Stability of Ant-plant Mutualistic Networks Mediated by Extrafloral Nectaries: Looking at the Effects of Forest Fragmentation in the Brazilian Amazon

Rainforest fragmentation drastically affects biodiversity and species composition, mainly due to habitat loss. Several studies have already shown the effects of forest fragmentation on plant and ant communities. To date, however, there is limited empirical knowledge of how forest fragmentation affects ant-plant interaction in networks. We investigated the effects of the configuration of rainforest fragments on the structure of ant-plant interaction networks mediated by extrafloral nectaries (EFNs). We carried out this study in ten forest fragments, ranging in size from approximately 5 to 3,000 ha, located in the Brazilian Amazon. In each fragment we established a plot of 6,250 m2, in which all ant-plant interactions were recorded, and calculated the following network descriptors: number of interactions, network size, network specialization, diversity of interactions, and nestedness. We used four explanatory variables to investigate the effects of forest fragmentation on these network descriptors: three metrics of the configuration of fragments (i.e., fragment area, edge irregularity, and connectivity) and the forest structure within each fragment, represented by canopy cover. We did not detect any effect of the explanatory variables on the network descriptors. The structural stability of the networks sampled in forest fragments with different configurations is possibly related to the observed constancy of ant species in the central core of highly interacting species. Our results corroborate other studies highlighting the structural stability of these facultative ant-plant networks mediated by EFNs in different spatial and temporal gradients. Nonetheless, the low constancy of plant species in the generalist core should be understood as a warning, mainly because the functionality of this protective mutualism (i.e., food secretions in exchange for protection against herbivory) remains unknown.

A systematic method for hypothesis synthesis and conceptual model development

Abstract Conceptual models are necessary to synthesize what is known about a topic, identify gaps in knowledge and improve understanding. The process of developing conceptual models that summarize the literature using ad hoc approaches has high potential to be incomplete due to the challenges of tracking information and hypotheses across the literature. We present a novel, systematic approach to conceptual model development through qualitative synthesis and graphical analysis of hypotheses already present in the scientific literature. Our approach has five stages: researchers explicitly define the scope of the question, conduct a systematic review, extract hypotheses from prior studies, assemble hypotheses into a single network model and analyse trends in the model through network analysis. The resulting network can be analysed to identify shifts in thinking over time, variation in the application of ideas over different axes of investigation (e.g. geography, taxonomy, ecosystem type) and the most important hypotheses based on the network structure. To illustrate the approach, we present examples from a case study that applied the method to synthesize decades of research on the effects of forest fragmentation on birds. This approach can be used to synthesize scientific thinking across any field of research, guide future research to fill knowledge gaps efficiently and help researchers systematically build conceptual models representing alternative hypotheses.

The Influence of Land Cover Change Towards Connectivity Networks of Forest Ecosystem in Tesso Nilo National Park

Tesso Nilo National Park is one of the protected areas designated as KPA by the Decree of the Minister of Forestry No.225/Menhut-II/2004 dated July 19, 2004 covering an area of ​​38,576 ha, then expanded again through the Decree of the Minister of Forestry No.663/Menhut/2009 dated 19 October 2009 with an area of ​​± 83,068 ha. The Tesso Nilo National Park area is experiencing the dynamics of land cover changes, namely the conversion of forest land which causes the forest area to become increasingly narrow in this area. With the reduction in forest area in this area, it causes a decrease in ecosystem network connectivity due to forest fragmentation that occurs, so that forests are separated and further apart. This study aims to analyze changes in land cover in the Tesso Nilo National Park area to find out information on changes in habitat ecosystems in the last 20 years. the observations were made using satellite images in 1999, 2010 and 2019. so that it can be seen the effect of forest fragmentation on ecosystems in the Tesso Nilo National Park area. From the results of the analysis, it was found that the area of ​​forest cover in the Tesso Nilo National Park decreased from 1999 to 2019 and caused changes in the connectivity network of forest ecosystems, which was found in the study, the weakest connectivity separated forest fragments as far as 17394.47 meters due to forest cover fragmentation.

Effects of forest fragmentation on the weight of understory birds at the Biological Dynamics of Forest Fragments Project in Amazonia

AbstractDeforestation and habitat fragmentation are known as the chief drivers of biodiversity loss. Less is known about the condition of species and individuals that remain in disturbed habitats. Theory predicts that resources are more limited after compared with before fragment isolation. Thus, we assessed how body condition of individual birds' changes in response to forest fragment isolation. We compared weights of the same individually banded birds caught in mist nets within 5 years before and after fragment isolation and assessed the population‐level changes of three species at the Biological Dynamics of Forest Fragments Project in the Brazilian Amazon. We predicted that fragment isolation would result in reduced weight for all bird species. Out of the 3466 bird mist net captures before and after isolation in the 1980s and the 2150 birds captured before and after re‐isolation of fragments in the 2010s, only 73 adult individuals from 36 different species were recaptured, suggesting that few individuals stay in fragments. Contrary to predictions, insectivorous species that remained in fragments gained weight (3.43%) after fragment isolation while frugivorous birds maintained a stable weight. While recent studies report long‐term declines in body mass of birds in tropical unfragmented tropical forests, our results provide a novel analysis into how avian body mass responds to habitat fragmentation. Further studies on the body condition of individuals that remain in fragments and the ultimate consequences of fluctuations in body condition are needed to better understand why some individuals and species are more susceptible to forest fragmentation than others.Abstract in Portuguese is available with online material

Effect of forest fragment size on Polistinae (Hymenoptera, Vespidae) in a transitional area of Cerrado and Atlantic Forest in south central Minas Gerais state, Brazil

Ecosystem fragmentation negatively affects biological diversity and compromises different environmental services. This situation occurs in two important biomes in Brazil, the Atlantic Forest and the Cerrado. There is little information on the effects of fragmentation on animal taxa, including social wasps. It was hypothesized that fragments that are small in size and subject to anthropogenic pressures have reduced social wasp richness and colony numbers. This study aimed to investigate the effect of forest fragmentation on Polistinae richness and colony number at Atlantic Forest and Cerrado sites in southern central Minas Gerais State, southeastern Brazil. The study was conducted in three fragments, Mata do Baú, Cachoeira da Lajinha, and Cachoeira do Padeiro, from October 2020 to March 2021, using active collection to record social wasp species and colony numbers. A total of 42 species and 80 colonies were recorded in the three fragments. Forest fragment size alone did not influence social wasp communities, but communities were significantly affected by a combination of factors, including fragment size, adjacent vegetation, and anthropogenic pressures. Species richness was higher in Mata do Baú and Cachoeira da Lajinha, which did not differ from each other, than in Cachoeira do Padeiro; however, all fragments had exclusive communities. Therefore, an increase in anthropogenic pressure in any of the three fragments may lead to losses in social wasp species.