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The role of mixed forests in tropical coastal South China is unclear due to a long history of afforestation with a Casuarina (Casuarina equisetifolia) monoculture. In this study, we determined how the stand dynamics and soil nutrients in monoculture stands of Casuarina equisetifolia were influenced by Acacia (Acacia mangium), a fast-growing pioneer species, when the two tree species were combined in two initial proportions. We also compared the canopy conditions of mixed and monoculture stands of C. equisetifolia at the young stage. Over a period of ten years, the density of stems was relatively low in C. equisetifolia ×Acacia mangium mixed stands compared to C. equisetifolia monoculture stands. By contrast, the aboveground biomass, understory diversity and soil nutrients were relatively high in C. equisetifolia ×A. mangium mixed stands, particularly when the initial mixing proportion of A. mangium was greater. Moreover, C. equisetifolia can protect A. mangium in the windy coastal environment by ensuring evenly distributed crown growth, intact canopy conditions, and high leaf area index (LAI) during the young stage. In conclusion, the two species had a positive interaction in the mixed forests, which suggests that coastal conservation managers need to shift from their traditional focus on C. equisetifolia single-species afforestation to multi-tree species mixed afforestation.
In South American forests, the Japanese raisin tree (Hovenia dulcis Thunb.) is an invasive tree that produces capsuled fruits attached to peduncles that grow thick and fleshy when ripe. Several frugivorous birds are reported to be dispersal agents of H. dulcis. The spread of H. dulcis propagules to non-invaded sites was evaluated at a local spatial scale in deciduous forests in Southern Brazil, in order to propose management strategies to prevent the arrival of propagules of such species in non-invaded sites. Seed arrival via birds was assessed by five 0.6 × 0.6 m seed traps in each of the 10 × 10 m plots in non-invaded sites at different distances from invaded sites. Seed arrival was also compared between control plots and plots where all H. dulcis trees were felled within a 30m radius from the center of plots. A limitation in short distance seed dispersal by birds was observed in the study area. There was a negative exponential relationship between number of seeds and distance from H. dulcis trees to non-invaded sites, and a positive exponential dependence of the number of seeds found in seed traps on the basal area of H. dulcis. Felling H. dulcis trees was effective in reducing the arrival of seeds in non-invaded sites, resulting in significantly fewer seeds in managed plots than in control plots.
Peru supports approximately 588 amphibian species, of which 492 have been assessed on the IUCN Red List of Threatened Species. Of these, 111 are classified as Threatened, with 69 species classified as Critically Endangered or Endangered. In addition, 140 amphibian species remain Data Deficient. We re-assessed the conservation status of 38 amphibian species originally identified as potentially Threatened by von May et al. (2008), using the IUCN Red List Categories and Criteria. Fourteen species assessments changed as a result of re-assessment, of which eight changed from Data Deficient to Threatened; two changed from Data Deficient to Near Threatened and Least Concern respectively; two were up-listed from Least Concern to a Threatened status; two were down-listed. None of the changes were due to a known genuine change since the previous assessment. All changes were justified by an increase in knowledge. The eight species with a change from Data Deficient to a Threatened category belonged to four anuran families: Craugastoridae, Dendrobatidae, Hemiphractidae and Telmatobiidae. The reasons for a change in assessment status were: changes in taxonomy, distribution, population status, threat status, or previously incorrect information. The main threat affecting re-assessed amphibian species was habitat loss, with other threats including pollution, disease outbreaks, and collection for the pet trade. Only 53% of the re-assessed species were found to occur in a protected area. Findings of this study indicate the continuing fragility of many Peruvian amphibians and highlight the need for improving their protection and for further research into their population status and threats.
The loss and degradation of forests in tropical regions have modified tree cover, creating deforested landscapes. It has been suggested that there are thresholds in these landscapes beyond which the diversity, distribution, abundance, and fitness of different biological groups can be affected. In this study, the ecological habitat thresholds were detected for eight populations of phyllostomid bats along an environmental gradient of forest loss in the Huasteca region, Mexico. At a local scale, we analyzed canopy loss, and we also detected these thresholds at the landscape level, as a function of forest remnant area at three scales with radii of 1, 3 and 5 km. The data were analyzed using the Threshold Indicator Taxa ANalysis (TITAN) method for detecting indicator species along gradients. The bats exhibited three different types of response to habitat loss: 1) Leptonycteris yerbabuenae, Chiroderma salvini, Sturnira hondurensis, and Artibeus lituratus were more abundant where canopy cover was present at the local site, even though the landscape had been deforested; 2) Sturnira parvidens and Artibeus jamaicensis required tree cover at all spatial scales; and 3) Glossophaga soricina and Desmodus rotundus are species that might be locally abundant in habitats with little canopy, but both species need landscapes that have not been deforested. In conclusion, these populations of phyllostomid bats were sensitive to deforestation in different ways, their response to the habitat loss gradient varying among species and with spatial scale.
Ecosystems in sub-Saharan Africa are highly vulnerable to external perturbations. An in-depth understanding of the socio-ecological mechanisms is important for the effective management of vulnerable ecosystems. Using remotely sensed satellite imagery and social data from 335 households, the study examines how different ecological and socio-economic factors influence ecosystem vulnerability in Morogoro region, Tanzania. Remotely sensed data indicated negative patterns of change in ecosystem health both at the spatial and temporal scales. Multiple logistic regression analysis showed habitat fragmentation and forest burning as key threats (p=0.02). From a social point of view, low income level (54.6%) and limited knowledge of environmental conservation (18.5%) were considered major catalysts of ecosystem vulnerability. Statistical results showed livelihood diversification (45.1%), effective institutional frameworks (30.7%), and afforestation programmes (24.2%) to be key intervention measures. The methodology and policy implications of the study have a wider applicability in the long-term management of vulnerable landscapes.
Increasing global human population and per-capita food consumption are expected to exacerbate the already massive agricultural footprint in tropical ecosystems. Madagascar is home to exceptional levels of biodiversity and is in the midst of severe land-use change, mostly driven by slash-and-burn, smallholder agriculture. Understanding the consequences of these agricultural practices for Malagasy native species is therefore of the foremost importance for the conservation of the nation's biodiversity. We surveyed bird assemblages inside and surrounding Ranomafana National Park, southeastern Madagascar, obtaining nearly 1,000 records of more than 60 species. At each study point, habitat structure was characterized by its vegetation complexity, and forest cover was quantified within circles of radii of 100, 500 and 750 m. We found that species richness was higher in forest than in agricultural areas, and responses to land-use change were found to be guild-specific, with frugivores being especially depleted outside forest areas, whereas granivores had higher species richness in the agricultural matrix. The number of recorded species with forest affinities was highly associated with landscape-scale forest cover, while open area and generalist species responded mainly to site-scale habitat structure. Our results demonstrate a turnover from forest-associated species to open area and habitat generalist species in Madagascar's smallholder agricultural areas. Our study underscores the conservation value of landscape-scale forest cover and of site-scale vegetation complexity. A double-stranded conservation approach, in which both landscape-scale forest cover and vegetation complexity are preserved would benefit conservation of the island's forest avifauna.
Remotely operated vehicles (ROVs) present a potential risk for the transmission of invasive species. This is particularly the case for small, low-cost microROVs that can be easily transported among ecosystems and, if not properly cleaned and treated, may introduce novel species into new regions. Here we present a set of 5 best-practice guidelines to reduce the risk of marine invasive species introduction for microROV operators. These guidelines include: educating ROV users about the causes and potential harm of species invasion; visually inspecting ROVs prior to and at the conclusion of each dive; rinsing ROVs in sterile freshwater following each dive; washing ROVs in a mild bleach (or other sanitizing agent) solution before moving between discrete geographic regions or ecosystems; and minimizing transport between ecosystems. We also provide a checklist that microROV users can incorporate into their pre- and post-dive maintenance routine.
Forests of Asia-Pacific islands have undergone degradation by some of the worst-known selective logging practices in the tropics. It is unclear whether severely damaged forests can return to a pre-logging state via natural regeneration, or whether active restoration is required. In this review, we highlight how the socioeconomic dynamics in the Solomon Islands promote excessive logging, resulting in highly degraded forests. We detail seven key elements currently promoting excessive logging in this region: (i) economic interests, (ii) corruption, (iii) poor employment conditions in the logging sector, (iv) high forest accessibility, (v) resource limitations for forest monitoring, (vi) contention over logging benefits, and (vii) a paucity of information for policy development. Though research on the regeneration capacity of logged forests in the Solomon Islands remains extremely limited, we suggest that some logged forests in the country may require active restoration—especially those that have been most heavily damaged. Our argument is based on previous tree planting initiatives in logged forest in the 1970s and 1980s. We propose three broad restoration techniques—enrichment planting, direct seeding, and the use of artificial perches—as viable options to help restore logged forests in the Solomon Islands. Lastly, we recommend the conservation-concession model to aid forest restoration, given its recent success in the region.
We discovered the presence of two individual spotted leopards Panthera pardus in Ulu Muda Forest Reserve, a previously under-researched selectively logged rainforest of Peninsular Malaysia. These findings are unexpected, because only two other studies have detected the spotted morph amongst many other melanistic leopards caught on camera traps in Peninsular Malaysia. We discuss the implications of our findings with respect to the prevalence of melanism among leopards in the region.
Potential agents of seedling mortality for Guam's only known Serianthes nelsonii (Håyun lågu) tree were determined from the in situ crop of emerging seedlings. We used insecticides to mitigate exotic arthropod pressure, fertilizer to mitigate nutrient deficiency, fungicide to mitigate root pathogen pressure, and supplemental lighting to mitigate low light stress. The fungicide treatment was the only treatment that elicited a substantial increase in seedling longevity. Past reports based on general observations point to insect and ungulate herbivory as likely agents of seedling mortality. Our results identify root pathogens as an additional cause of mortality at the study site. Results may be useful for designing more complex experiments to improve species recovery efforts.
Reliable baseline information necessary for the monitoring and conservation of Sumatran elephants is scarce. We here combine non-invasive molecular genetics methods and capture-recapture modeling to estimate elephant population size, distribution, sex ratio, and age structure for the Bukit Tigapuluh landscape in Sumatra, Indonesia. Two separate subpopulations were found, for which we estimated a population size of 99 (95% CI = [86,125], PCCL = 38.59%) and 44 elephants (95% CI = [37, 56], PCCL = 43.18%), respectively. Low elephant densities are likely the result of patchy habitat usage and anthropogenically increased mortality, the latter assumption being supported by strong skews in both sex ratio and age structure as well as direct evidence of elephant killing. Still, the Bukit Tigapuluh landscape currently holds the largest known population of elephants in central Sumatra, representing one of the most important areas for their conservation in Indonesia. Conservation of both the elephant population and their habitat in this region should thus be of high priority. We identified several threats to the population, including (i) the risk of inbreeding and subsequent loss of genetic diversity, (ii) illegal elephant killing, and (iii) the lack of protected habitat. In order to overcome these challenges we suggest: (i) the implementation of a meta-population management program, (ii) monitoring and safeguarding elephants and improving law enforcement, and (iii) providing sufficient safe habitat to mitigate human-elephant-conflict (HEC) and ensure elephant survival.
Carnivores, particularly felids, face threats in many regions of the world. They are a crucial component of biodiversity with a functional role in the top of the food chain. Therefore, they have been the target of surveys and monitoring and ecological studies, most of which are based on footprint identifications, an efficient and low-cost method compared to other approaches. In these cases, species identifications may suffer from a high degree of bias due to the overlap in the size and shape of footprints among species. We experimented with small to medium captive wild felids of five species: ocelot, Leopardus pardalis, margay L. wiedii, oncilla, L. guttulus, domestic cat, Felis catus, and jaguarondi, Puma yagouaroundi). We tested for differences in footprint measurements, including main pad and toe pad sizes. We used humid sand as substrate and took measurements from several front and hind footprints of seven animals per species (except jaguarondi, for which only four animals were available). Our results showed that ocelot is the only species for which it is possible to obtain 100%-accurate footprint identifications, mainly because of its footprint area (i.e., length × width). The remaining species presented a wide variation in measurements, making them almost impossible to distinguish based solely on footprint dimensions. Our results suggest that researchers should restrict identification to the genus level or adopt a multidisciplinary sampling strategy by combining footprint detection with camera-trapping, visual observation, scat collection, molecular ecology techniques, and/or face-to-face interviews with local residents.
Ceratozamia fuscoviridis, or teosintle in nahuatl, is a recently rediscovered endangered cycad species previously known from only one population (Molango) in Sierra Madre Oriental of the State of Hidalgo, Mexico. Recent botanical explorations have found new but scattered populations, increasing its known geographical range. Ecological studies were conducted on six of the 29 populations found. Parameters such as size, density, population structure, and static life table are presented. This is the first study of its kind conducted to prompt the Mexican authorities to establish natural protected areas for this species and the associated biodiversity, because deforestation is rapidly diminishing the populations. The population structure in general showed a Deevey-III curve, while two populations showed Deevey-I curves. A 400 m2 area had a population size from 143 to 378 individuals. Population density varied from 0.358 individuals/m2 to 0.945 individuals/m2. Population structure was statistically different among populations. The large amount of seedlings in all sites was distinctive and indicated the specie's reproductive success even in small forest fragments. This research provides the most complete information available to date regarding populations of C. fuscoviridis. Future protected areas established in the better conserved populations could enable the populations' rapid recovery. This study shows that C. fuscoviridis is not as restricted in area as previously believed. We suggest the IUCN Red listing category of the species be amended from Critically Endangered (CR) to Endangered (EN) in view of newly discovered populations, high population size, and successful recruitment.
Endemic to two lakes (Ayamaru and Uter) of West Papua (Indonesia), the Boeseman's Rainbowfish Melanotaenia boesemani Allen & Cross, 1980 is a very popular ornamental freshwater fish. As a result, this rainbowfish species faces great threats and is on the red list of endangered species. Therefore, rearing of this species in aquaculture systems appears to be a promising solution to limit capture of wild specimens and prevent its extinction. Although its reproduction cycle has been controlled for more than 30 years, very few farms still raise M. boesmani, probably due to the problems reported by the farmers, such as decline of production, higher proportion of females per spawning, loss of coloration, lower growth rate and fecundity. Using 12 microsatellites previously developed for this species, comparison of genotypes within six farms around Jakarta indicated that all reared strains originated from Ayamaru Lake. No deficit in heterozygotes was evidenced, suggesting that there was no major inbreeding in these reared populations. Genotype analysis also suggested that M. boesemani species is a metapopulation composed of genetically differentiated populations. Altogether, these results indicate that the problems experienced by the farmers are due not to inbreeding depression but to other factors such as inadequate management and/or poor water quality. Yet, increasing aquaculture production is probably the most effective way to alleviate the pressure that M. boesemani faces in its natural environment.
José Severino Bento-Silva, Wbaneide Martins de Andrade, Marcelo Alves Ramos, Elba Maria Nogueira Ferraz, Wedson de Medeiros Souto, Ulysses Paulino de Albuquerque, Elcida de Lima Araújo
This research assessed the relationship between students' perceptions and socioeconomic factors in urban and rural communities surrounding Atlantic rainforest protection areas in Pernambuco, Brazil. We tested whether the utilitarian concept of forests has a determining role in the student community's perception of protected areas. The study was conducted in eight schools in communities surrounding three protected areas, through questionnaires for 410 middle and High school students. The majority of students highlighted the utilitarian importance of forests, but approximately 60% of students did not answer the question regarding the importance of protected areas, displaying a disconnection between perceptions of forests and of protected areas. The students' environmental perception index was significantly different between rural and urban zones, but in both zones, on average, protected areas had a positive utilitarian importance, exclusively related to the protection of nature. Negative aspects of the students' perceptions of protected areas were related to social problems such as lack of law enforcement and land expropriation. Schooling and residence setting had a small (6.7%) but significant influence on student perception. Our results indicate that environmental managers in protected areas need to promote meaningful interaction with student communities from rural and urban settings, to increase the efficiency of these areas and to conserve biological diversity.
The inexorable expansion of oil palm plantations has been a major driver of biodiversity loss in the tropics. This is particularly evident in Malaysia and Indonesia, where the majority of the world's oil palm is cultivated. In Latin America oil palm acreage has also been steadily increasing, especially in countries such as Colombia, the largest producer by far. However, information on the biological implications of rapid land conversion to oil palm in the region remains scarce. Here, we review the state of knowledge about the impacts of oil palm on biodiversity in Colombia. We also discuss the conservation strategies that have been implemented in the country, and propose research that we need to develop best management practices. The vast majority of research has focused on biotechnology, soils, biological pest control, carbon stock and reduction of greenhouse gases emission, but research on biodiversity is very scarce, or is not published yet. However, important investment and research on this topic are being developed. The most threatened ecosystems are the savannas in the Orinoquia region, where most of the expansion is predicted. The demands for green markets and certification are slowly encouraging oil palm corporations to mitigate their ‘biological footprint‘. However, applied research on the possible impacts of oil palm on biodiversity are urgently needed to support conservation efforts in the oil-palm-dominated landscapes of Colombia, along with commitments by the government and companies to adopt the resulting recommendations.
Hovenia dulcis (the Japanese raisin tree) is an invasive tree in seasonal deciduous forest in Southern Brazil. The species has an uncommon infructescence morphology, with dry fruits attached to fleshy peduncles that attract animals. This study assesses the interaction between the raisin tree and frugivore animals in seasonal deciduous forest and identifies potential dispersal relationships. Local fauna consumers and dispersers of the raisin tree were recorded by camera traps and by focal observation. Fruit removal was assessed by experiments that excluded certain animal groups while allowing access by others. We assessed seed dispersal by endozoochory by collecting the feces of birds and mammals found in the study area. The seeds found in the animal feces were then subjected to germination tests. A sampling effort of 2,305 traps/day was taken during the fructification period of the raisin tree. As a result, 28 species (16 birds and 12 mammals) were recorded from pictures taken by camera traps, and two more bird species were recorded via focal observation, for a total of 30 recorded species. Intact seeds of the raisin tree were found in the feces of Cerdocyon thous (crab-eating fox). No difference was found in seed germination between seeds obtained from fecal samples and the control. Ants can also be secondary dispersers of the raisin tree based on two observations made during the research field trips. The results obtained from this study suggest the raisin tree has different dispersal mechanisms with which different native dispersal agents are associated. Mid-size mammals, such as the crab-eating fox, are secondary dispersers by endozoochory, while birds are primary dispersers by sinzoochory.
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