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Tropical Ecology
International Society for Tropical Ecology
Tropical Ecology

International Society for Tropical Ecology

0564-3295

Tropical Ecology/Journal Tropical EcologyISTPSCI
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    Migration ecology in the freshwater eels of the genus Anguilla Schrank, 1798

    Arai, Takaomi
    16页
    查看更多>>摘要：Science has long attempted to understanding the mysteries of migration in the freshwater eels of the genus Anguilla. Freshwater eels are of tropical marine ancestor and have spread worldwide. As diadromous fish species, freshwater eels are eminent for their incredible migrations between offshore spawning grounds and fresh water habitats from local to global scales. Freshwater eels can be distinguished into three migratory phases throughout their lives: oceanic migration to continental habitats, continental migration and oceanic migration to spawning grounds. Spawning grounds of the freshwater eels are all located in tropical waters (lower latitude), and the larvae drift from the tropical ocean to tropical growth habitats or are further colonized to temperate growth habitats through ocean currents. The spawning period and duration of the planktonic larval period stir global dispersal, biogeography and their subsequent speciation in freshwater eels. Year-round spawning, constant larval growth and shorter larval duration lead to short-scale oceanic migration to tropical growth habitats with annual colonization in tropical freshwater eels. In temperate freshwater eels, the limited spawning season, longer larval duration, and separate larval growth lead to large-scale migration to temperate growth habitats and seasonal recruitment to continental habitats. The year-round maturation in tropical freshwater eels and seasonal maturation in temperate freshwater eels lead to year-round spawning and seasonal spawning, respectively. During their continental lives just before the initiation of oceanic migration for spawning, diverse migration and habitat uses in fresh, brackish and marine waters are commonly found in tropical and temperate freshwater eels. Freshwater eels do not necessarily live in freshwater habitats and thus are believed to display opportunistic catadromous migration. The most enigmatic part of spawning migration in freshwater eels from the continental growth habitats to spawning grounds has gradually been uncovered by means of the empirical research. Research advances and endeavors for centuries have progressively unveiled the mystery of migration ecology in freshwater eels.
      原文链接:
    • NSTL
    • Springer Nature

    Variation among individuals of Citrullus colocynthis from a desert population in morphological, genetic, and germination attributes

    Al-Nablsi, ShaimaaEl-Keblawy, AliMosa, Kareem A.Soliman, Sameh...
    12页
    查看更多>>摘要：Variations in fruit size, color, and stripe pattern on fruit rinds have been noticed among individuals within Citrullus colocynthis (Cucurbitaceae) populations in the hyper-arid deserts of the UAE. The present study aimed at assessing variations in fruit and seed characters, germination behavior, and genetic diversity among 12 individuals (hereafter referred accessions) collected from one population. Results showed that the accessions differed in seed dormancy level and response to light and temperature of incubation. The overall germination ranged between 18.5% in accession number 9 and 56.6% for accession number 2. At lower temperatures (15/25 degrees C), little germination occurred in darkness but not in the light. Germination was significantly greater and faster (germination rate index was higher) at higher temperatures (25/35 degrees C) than moderate (20/30 degrees C) and lower temperatures. Germination was greater in light than darkness in almost all accessions at higher temperatures but not at moderate temperatures. Random amplified polymorphic DNA (RAPD) analysis showed polymorphism varied between 90 and 100%, with polymorphic information content values ranged from 0.28 to 0.37 with an average of 0.33. Few individuals showed high genetic similarities, while most of them had similarity coefficients less than 0.5. There were moderate to weak relationships between genetic similarities and germination behavior of the different accessions.
      原文链接:
    • NSTL
    • Springer Nature

    Geospatial modeling of forest cover dynamics and impact on climate variability in Awi Zone, Ethiopia

    Mekasha, Samson TsegayeSuryabhagavan, K., VKassawmar, Tibebu
    17页
    查看更多>>摘要：Globally, forest habitats are threatened by human-induced deforestation and degradation. This study was aimed to assessing changes in land-use patterns in Awi Zone, Ethiopia, during the last 34 years and its relationship with land surface temperature (LST) and rainfall using digital change detection approaches. Multi-temporal Landsat imagery (1985, 2000, 2009, and 2019), MODIS, and CHIRPS were used in combination with Google Earth and field data for this study. Support vector machine classification technique was used to produce LULC maps. Mann-Kendall test for LST (2000-2019) and rainfall (1981-2019) was used to compute non-parametric trend analysis. Results revealed that 47,255.5 ha of forest and 24,674.9 ha of other land-cover types had increased from 1985 to 2019. In contrast, agriculture and bare land had decreased by 16,819.9 ha and 55,110.5 ha, respectively. In Dega agro-climatic zone, mean and minimum LST trend analysis has revealed a significant decrease. Sen's slope shows mean, minimum, and maximum LST decreasing trend at 0.13 degrees C/yr., 0.12 degrees C/yr. and 0.10 degrees C/yr., respectively. In Woyna Dega and Kolla, LST trend analysis showed decreasing and increasing trends from 2000 to 2019. Coefficient of determination (r(2)) of forest cover and mean LST for Dega, WoynaDega, and Kolla zones revealed 0.98, 0.81, and 0.20, respectively. Kolla is highly influenced by anthropogenic factors and rapid urbanization that caused depletion of forest cover and conversion of farmlands into human settlements. In future, community-based land-use and land-cover planning and sustainable forest management system are recommended to protect, conserve and rehabilitate the remaining natural environment in the study area.
      原文链接:
    • NSTL
    • Springer Nature

    Debarking as a control method for invasive tree species management in tropical forests

    Bempah, Ahmed NsiahKyereh, BoatengAnsong, MichaelAsante, Winston...
    9页
    查看更多>>摘要：Our study assessed the effectiveness of species debarking in controlling species invasion and the change in seedling dynamics after application of the different treatments. A split plots design was used in two forest reserves to assess the effectiveness of three debarking treatments: complete ring debarking, partial ring debarking and a control (no debarking). The results reveal that ring debarking has the potential to be used to control invasive species such as Cecropia peltata L. and Broussonetia papyrifera (L.) Vent. The efficiency, however, was influenced by the extent of the wound created and the size of tree, especially if trees are partially debarked. The control method also stimulated natural regeneration of native species with higher regeneration of native species recorded compared to invasive species. Also, plots that had completely debarked trees had higher species diversity than the partially debarked and the control plots in one of the reserve. The fact that none of the trees in the control plots died is indication of the effectiveness of debarking in the control of invasive species considered here. The effectiveness of this method suggests it is a suitable option for killing small to medium size trees with little cost to the environment compared to the application of arboricides for instance and is therefore worth revisiting in silvicultural treatments where minimum environmental disturbance is required. We recommend more studies to compare the effectiveness of the control approaches on different invasive species and monitor how the native communities respond including in terms of species diversity and functional groups, since removal methods may impact differently on these plant community traits.
      原文链接:
    • NSTL
    • Springer Nature

    Spiders as bio-indicators of habitat disturbance in the riparian zone of the Ganga river: a preliminary study

    De, KritishSiliwal, ManjuUniyal, Virendra PrasadHussain, Syed Ainul...
    7页
    查看更多>>摘要：Bio-indicators are extremely useful for quickly assessing the true condition of a rapidly deteriorating freshwater environment at a low cost. Global research has shown that the spider (Arachnida: Araneae) is a well-known taxon with bio-indicator potential. Present study was performed to find out if any spider species could be used as a bio-indicator of undisturbed habitat for Gangetic riparian zone. For the study, total 27 sites were selected along the Ganga River's banks, with an average distance of 75 kms between each site. Based on disturbance ratings, the sampling sites were divided into five groups: very low disturbed sites, low disturbed sites, moderately disturbed sites, highly disturbed sites and very highly disturbed sites. The non-parametric analysis of similarities (ANOSIM) test and non-parametric permutational multivariate analysis of variance (PERMANOVA) were used to understand similarities of species composition between these groups. The redundancy analysis (RDA) was performed to investigate the relationship between spider distribution and habitat disturbance. The indicator value (IndVal) method was used to find out significant bio-indicator spider species for habitat disturbance. The study found that the agriculture, human occupation, manmade embankment, and sand mining were the most effective combination of disturbance that affects spider assemblage and eight species can be used as indicator of very low disturbed sites and one species can be used as indicator of low disturbed sites.
      原文链接:
    • NSTL
    • Springer Nature

    Host identity and neighborhood trees affect belowground microbial communities in a tropical rainforest

    Cowan, Jacob A.Gehring, Catherine A.Ilstedt, UlrikGrady, Kevin C....
    13页
    查看更多>>摘要：The roots and rhizospheres of trees harbor diverse microbial communities that can modulate plant competition and facilitation, thereby influencing plant community dynamics. Understanding the factors structuring microbial communities is valuable for predicting how plant communities assemble. In temperate forests, host identity, biotic neighborhood, abiotic environment and geographic distance shape microbial communities, but the importance of these factors is less well studied in highly diverse tropical forests. In this study, we used high-throughput amplicon sequencing to characterize the arbuscular mycorrhizal fungal (AMF) and rhizosphere bacterial (RB) communities of five tree species in an 8-year-old common garden planted into the understory of a selectively logged old-growth forest in Malaysian Borneo. We assessed the influence of host tree species, host traits and neighboring tree identity on the composition and diversity of both communities. The AMF and RB communities differed amongst host tree species; the tree species with the most distinct AMF communities associated with the lowest diversity of AMF. Alpha diversity of AMF correlated negatively with leaf phosphorus and potassium content. Density and abundance of AMF neighbor trees growing near focal trees influenced AMF community composition and was positively correlated with RB alpha diversity. Our results highlight the importance of considering both host tree identity and biotic neighborhood of trees in studies of microbial communities in tropical forests. Important next steps will be to elucidate the functional significance of shifts in AMF and RB community compositions and their implications for community and ecosystem dynamics in tropical forests.
      原文链接:
    • NSTL
    • Springer Nature

    Bird diversity along a gradient of tropical forest loss due to agriculture in central Veracruz, Mexico

    Alducin-Chavez, Gerson D.Moreno, Claudia E.Rojas-Soto, Octavio
    10页
    查看更多>>摘要：Tropical ecosystems have undergone severe changes due to human activities such as land-use change for agriculture. However, in agricultural landscapes with remnants of native vegetation, high bird diversity may persist. Here we evaluated bird species richness, diversity, and composition in four landscape units with different matrices: cattle pastures, cornfields, mixed mosaics, and continuous forest. Using nets and direct observations, we recorded 138 bird species. We expected species richness to have a negative relationship with agricultural coverage, thus decreasing in the following sequence of landscape matrices: forest > mixed > corn > pasture. On the contrary, standardized species richness decreased from 122 to 93 species in the following sequence: pasture > mixed > forest > corn. Using a PERMANOVA, we detected significant changes in species composition among landscape units. These differences were represented in a NMDS plot and a Venn Diagram. Species diversity (Hill Numbers) also changed seasonally, and the forest unit had low richness but the highest evenness. This complex landscape allowed the presence of diverse species under risk categories. We conclude that despite recurrent human disturbances in this tropical region, the agricultural landscape, mixed with remnants of natural vegetation, allows the maintenance of highly diverse bird communities, probably due to spatial dynamics among landscape elements.
      原文链接:
    • NSTL
    • Springer Nature

    The influence of tree population structure on regeneration potential in the sacred forests of Assam, India

    Baidya, ShilpaThakur, BijayDevi, Ashalata
    13页
    查看更多>>摘要：Sacred forests protected through nature beliefs have undergone successional stages to form the climax vegetation harbouring rich biodiversity. The study on the effect of population structure on the regeneration status of tree species is limited in the sacred forests. The present study was carried out in four sacred forests of Assam wherein 57 tree species belonging to 51 genera under 28 families were recorded. The correlation of girth class with species richness, density, and basal area of trees showed a significant negative relationship. One-way ANOVA on ranks proved a significant impact of girth class on the number of individuals of species, F(10) = 36.46, p < 0.05. A reverse J-shaped GBH-density distribution revealed that most species have higher individuals in lower girth classes (0-30 cm) with steady growth. The regeneration capacity of tree species in the sacred forests showed seedlings (741) > saplings (485) < adults (514). Putranjiva roxburghii Wall. and Bauhinia purpurea L. recorded as the dominant species having maximum density ha(-1) in the seedling stage. Overall, the regeneration of tree species showed maximum status in 'fair' followed by 'good', 'poor' and 'not regenerating' category. Sacred forests are privileged to have rich diversity; however, considerable changes due to environmental stress or interference exerted by human activities may distress the structural and functional composition of the forests.
      原文链接:
    • NSTL
    • Springer Nature

    Impacts of soil qualities and Prosopis juliflora on density, canopy volume and community position of Leptadenia pyrotechnica in Arid regions of India

    Mathur, ManishKumar, MaheshPandey, C. B.
    11页
    查看更多>>摘要：In the present study, we explored how the combination of site soil qualities and invasion by Prosopis juliflora affects the species specific (Leptadenia pyrotechnica) morphological (canopy volume) and population traits (density and Relative Importance Value) in an arid region of the India. For this, we surveyed 9 sites, categorized under two scenarios sites (n = 5) invaded by P. juliflora (Scenario 1), and sites (n = 4) un-invaded with P. juliflora (Scenario 2). With respect to sites, density of both these species exhibited reverse trends to each other. Similar trends were also recorded for canopy volume and cover of L. pyrotechnica and P. juliflora, respectively. We found log-normal distribution types at all the studied sites. In our empirical study, fifteen Relative Importance Value (RIV) of P. juliflora was identified as threshold level beyond which it can drastically reduced the community diversity and niche space of various associates. Further, Relative Severity of Competition (RSC for density, canopy volume and cover) suggested that density (RSC 0.24) and canopy volume (RSC 0.20) of L. pyrotechnica suffered most due to invasion of P. juliflora. Partial Least Square (PLS), regression suggested that density of L. pyrotechnica and P. juliflora are orthogonal to each other indicated significant negative relationships between both of them (r(2) = - 0.95). Soil potassium and organic carbon are located close to density of L. pyrotechnica that is both these two variables have positive impacts with density (r(2) = 0.95). Similar positive relationships also observed between canopy volume and clay content (r(2) = 0.95), while, sand content was orthogonal to this parameter (r(2) = - 0.95). Present study suggested how the invasive P. juliflora along with certain soil factors controls the population, morphological and community position attributes of L. pyrotechnica.
      原文链接:
    • NSTL
    • Springer Nature

    Comparison among allometric models for tree biomass estimation using non-destructive trees' data

    Pandey, Hari PrasadBhandari, Shes KantaHarrison, Steve
    10页
    查看更多>>摘要：The non-destructive method-using allometric models-of forest biomass estimation is one of the most effective and efficient approaches, however, there is an ambiguity to choose a particular type of model for predicting biomass. The study aimed to compare 11 different allometric models generally employing in Nepal using empirical data of 4,942 individual standing trees of 36 species from 134 sample plots considering 20 environmental variables from five community forests belonging in two ecological regions. Akaike Information Criterion (AIC), coefficient of determination (R-2), and root mean square error (RMSE) of each model was estimated and compared. The biomass density predicted by different models differed significantly (p < 0.05) despite employing the same data set. A variation on the estimated biomass density differed from 4% (M4 and M11) to 364% (M5 and M10) among the models considered for the study. Results show that no models have relatively higher R-2 (less than 0.61), lower AIC (more than 813) and RMSE (more than 16). This indicates that hardly any existing general models in Nepal estimates actual biomass of the forest ecosystems. The results suggest that a universal model may not be applicable for the given condition, indicating an imminent need for the development of allometric models for biomass prediction based on species type, ecological regions, degree of disturbances, considering diversity variables, and ground and crown cover scenario of the forests. Such models require regular calibration for validity, reliability, credibility, and integrity of forest data management. The results would be a reference for policymaker and forest conservationists to select appropriate allometric equation and, thereby accurate prediction of biomass and timber volume, which in turn, will have good value for REDD + (carbon payment from forestry sector) and other economic conversions of the forests' biomass.
      原文链接:
    • NSTL
    • Springer Nature