The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Chihyu Chiu - One of the best experts on this subject based on the ideXlab platform.

  • composition of bacterial communities in sand dunes of subtropical Coastal Forests
    Biology and Fertility of Soils, 2014
    Co-Authors: Yute Lin, Tsaihuei Chen, William B Whitman, David C Coleman, Chihyu Chiu
    Abstract:

    Coastal sand dunes are a hostile environment for Forests. Little is known about the composition and diversity of the bacterial community in forest soils established on sand dunes. This study examines the soil bacterial community in the upland and lowland Casuarina and lowland Hibiscus successional Forests in a Coastal sand dune ecosystem. The 16S rRNA gene clone libraries were constructed to analyze the structure and diversity of communities. The Acidobacteria and Proteobacteria predominated in the sand dune forest communities, but the proportions of some phylogenetic groups differed among three communities. Some Actinobacteria- and Bradyrhizobium-related clones were only present or abundant in Casuarina forest soils. Because Casuarina could support a symbiotic, N2-fixing soil bacterial community, the composition of the microbial community may reflect its potential roles in the nitrogen budget and the effects of vegetation. Based on the diversity indices, the lowland Casuarina soils had the least diverse community, and the upland Casuarina community was the most diverse. Compared to an inland natural forest community, the dune communities were more diverse and had different proportions of abundant bacterial groups from those in the inland soils. The distribution of the abundant operational taxonomic units also differed among Coastal and inland Forests. The topography and vegetation type could affect the soil bacterial community composition in sand dune Forests. The high diversity of soil bacterial community may be a result of the succession phase of the sand dune ecosystem.

  • soil microbial communities and activities in sand dunes of subtropical Coastal Forests
    Applied Soil Ecology, 2011
    Co-Authors: Edhaun Chang, Chien Teh Chen, Tsaihuei Chen, Chihyu Chiu
    Abstract:

    Abstract To understand the soil microbial activities and community structures in different Forests in a sand-dune ecosystem, we conducted a study of 2 topographic conditions, upland and lowland, under a Casuarina forest. As well, in the lowland site, we compared forest soil microbial properties under 3 Coastal Forests (Casuarina, Hibiscus and mixed stand). The soil microbial biomass did not significantly differ between the upland and lowland Casuarina forest sites. At the lowland site, the soil microbial biomass was higher in the Hibiscus than Casuarina forest soil. Cellulase, xylanase, phosphatase and urease activities did not show a consistent trend by topography or vegetation. Analysis of phospholipid fatty acids (PLFAs) of bacteria and actinomycetes revealed a significant difference in microbial community structure by both topography and vegetation. PLFA content was higher at upland than lowland sites in the Casuarina forest. At the lowland site, the level of PLFAs was higher in Hibiscus than Casuarina forest soil. In addition, we examined the ratios 16:1ω7t/16:1ω7c and, cy17:0/16:1ω7c as indicators of physiological stress; the soil in the Casuarina forest had the highest values, which suggests that the microbial community in the Casuarina forest soil is under physiological stress or starvation conditions. Comparison of soil microbial properties suggest that planting Hibiscus may help to enrich soil fertility and increase microbial activities in Coastal sand-dune Casuarina forest.

Pieter Ignatius Olivier - One of the best experts on this subject based on the ideXlab platform.

  • forest floor temperature and greenness link significantly to canopy attributes in south africa s fragmented Coastal Forests
    PeerJ, 2019
    Co-Authors: Marion Pfeifer, Michael Boyle, Stuart Dunning, Pieter Ignatius Olivier
    Abstract:

    Tropical landscapes are changing rapidly due to changes in land use and land management. Being able to predict and monitor land use change impacts on species for conservation or food security concerns requires the use of habitat quality metrics, that are consistent, can be mapped using above-ground sensor data and are relevant for species performance. Here, we focus on ground surface temperature (Thermal ground) and ground vegetation greenness (NDVI down) as potentially suitable metrics of habitat quality. Both have been linked to species demography and community structure in the literature. We test whether they can be measured consistently from the ground and whether they can be up-scaled indirectly using canopy structure maps (Leaf Area Index, LAI, and Fractional vegetation cover, FCover) developed from Landsat remote sensing data. We measured Thermal ground and NDVI down across habitats differing in tree cover (natural grassland to forest edges to Forests and tree plantations) in the human-modified Coastal forested landscapes of Kwa-Zulua Natal, South Africa. We show that both metrics decline significantly with increasing canopy closure and leaf area, implying a potential pathway for upscaling both metrics using canopy structure maps derived using earth observation. Specifically, our findings suggest that opening forest canopies by 20% or decreasing forest canopy LAI by one unit would result in increases of Thermal ground by 1.2 °C across the range of observations studied. NDVI down appears to decline by 0.1 in response to an increase in canopy LAI by 1 unit and declines nonlinearly with canopy closure. Accounting for micro-scale variation in temperature and resources is seen as essential to improve biodiversity impact predictions. Our study suggests that mapping ground surface temperature and ground vegetation greenness utilising remotely sensed canopy cover maps could provide a useful tool for mapping habitat quality metrics that matter to species. However, this approach will be constrained by the predictive capacity of models used to map field-derived forest canopy attributes. Furthermore, sampling efforts are needed to capture spatial and temporal variation in Thermal ground within and across days and seasons to validate the transferability of our findings. Finally, whilst our approach shows that surface temperature and ground vegetation greenness might be suitable habitat quality metric used in biodiversity monitoring, the next step requires that we map demographic traits of species of different threat status onto maps of these metrics in landscapes differing in disturbance and management histories. The derived understanding could then be exploited for targeted landscape restoration that benefits biodiversity conservation at the landscape scale.

  • the use of habitat suitability models and species area relationships to predict extinction debts in Coastal Forests south africa
    Diversity and Distributions, 2013
    Co-Authors: Pieter Ignatius Olivier, Rudi J Van Aarde, Amanda T Lombard
    Abstract:

    Aim Predicting extinctions before they are realized has proven difficult, yet is increasingly important for biodiversity conservation as habitat destruction continues unabated around the world. We evaluated whether habitat suitability models can be used in conjunction with species–area relationships (SAR) to detect apparent extinction debts as implicated by the conservation status assigned to bird species. Location KwaZulu-Natal province, South Africa. Methods We modelled historic distributions of Coastal Forests using MaxEnt, a presence-only technique for modelling species distributions. The model provided an estimate of forest loss. We then conducted 293 point counts to survey birds within remaining forest fragments and employed an information-theoretic framework to test for the best fit SAR model. Extinction debts were calculated using the estimate of forest loss and the empirical SAR data. Results Our model suggests extensive forest loss (82%) within a naturally fragmented landscape. The power function provided the best fit for bird SAR. Fourteen bird species are predicted to go extinct from Coastal Forests. Predicted extinctions closely matched the number of threatened species locally but not globally. Predicted extinctions also only matched globally threatened species that reach their northernmost distribution limit within Coastal Forests, but not species that reach their southernmost distribution limit here. Main conclusions We found that habitat suitability models could be used in conjunction with SAR to estimate extinction debt implied by conservation statuses of extant species. Our approach assumed that forest loss drives extinction debts but also provided the opportunity to link forest loss and the likelihood of extinction. Models of historical forest distribution may provide guidelines of where to implement restoration actions. Maintaining matrix habitats that link forest fragments and targeted landscape level restoration that increases fragment area and link isolated fragments will be important to prevent predicted extinctions.

Nobuhito Mori - One of the best experts on this subject based on the ideXlab platform.

Zhenhua Huang - One of the best experts on this subject based on the ideXlab platform.

  • long waves through emergent Coastal vegetation
    Journal of Fluid Mechanics, 2011
    Co-Authors: Chiang C Mei, Philip L F Liu, Ichi Chan, Zhenhua Huang, Wenbin Zhang
    Abstract:

    We study the effects of emergent Coastal Forests on the propagation of long surface waves of small amplitude. The forest is idealized by an array of vertical cylinders. Simple models are employed to represent bed friction and to simulate turbulence generated by flow through the tree trunks. A multi-scale (homogenization) analysis similar to that for seepage flows is carried out to deduce the effective equations on the macro-scale. The effective coefficients are calculated by numerically solving the micro-scale problem in a unit cell surrounding one or several cylinders. Analytical and numerical solutions for wave attenuation on the macro-scale for different bathymetries and Coastal forest configurations are presented. For a transient incident wave, analytical results are discussed for the damping of a leading tsunami. For comparison series of laboratory data for periodic and transient incident waves are also presented. Good agreement is found even though some of the measured waves are short or nonlinear.

  • interaction of solitary waves with emergent rigid vegetation
    Ocean Engineering, 2011
    Co-Authors: Zhenhua Huang, Yu Yao, Shawn Y Sim, Yao Yao
    Abstract:

    Abstract In this study, solitary wave interaction with emergent, rigid vegetation was studied numerically and experimentally. Laboratory experiments were carried out in a wave flume with vegetation models of different lengths and porosities; the Boussinesq equations with the effects of the vegetation being modeled by a quadratic drag law are used to simulate the wave scattering by and the wave propagation through vegetation. Effects of incident wave height, vegetation density, and vegetation length are discussed. An empirical expression for the mean drag coefficient of emergent, rigid vegetation is presented and compared with other available data. The results are useful for studying tsunami hazard mitigation by Coastal Forests.

Sergio Fagherazzi - One of the best experts on this subject based on the ideXlab platform.

  • sea level rise and storm surges structure Coastal Forests into persistence and regeneration niches
    PLOS ONE, 2019
    Co-Authors: William S Kearney, Arnold Fernandes, Sergio Fagherazzi
    Abstract:

    The retreat of Coastal Forests as sea level rises is well documented; however, the mechanisms which control this retreat vary with the physical and biological setting of the interface between tidal marsh and forest. Tidal flooding and saltwater intrusion as well as flooding and wind associated with storms can kill trees. Even if these processes do not kill stands, they may halt regeneration because seedlings are more sensitive to stress. We present a case study of a Coastal pine forest on the Delmarva Peninsula, United States. This forest contains a persistent but nonregenerating zone of mature trees, the size of which is related to the sea level rise experienced since forest establishment. The transgression of Coastal forest and shrub or marsh ecosystems is an ecological ratchet: sea-level rise pushes the regeneration boundary further into the forest while extreme events move the persistence boundary up to the regeneration boundary.