Substrate Depth Research Articles

Influence of Wetland and Landscape Characteristics on Freshwater Turtle Relative Abundance and Movement Patterns in West Virginia, USA

Wetland management practices often alter habitat characteristics to improve the function of the wetland (e.g., removing emergent vegetation for aesthetics or dredging for fish stocking), potentially at the cost of reducing habitat quality for wetland-dependent species such as freshwater turtles. We identified wetland and surrounding landscape characteristics related to painted turtle (Chrysemys picta) and snapping turtle (Chelydra serpentina) relative abundance and snapping turtle movement among wetlands. We surveyed turtles at 29 wetland sites (0.04–1.71 ha) in a mixed-use watershed in north-central West Virginia, USA, where hardwood forests and wetlands have been heavily fragmented by agriculture and roads. We also applied radio transmitters to 33 adult snapping turtles (17 females and 16 males) across 17 wetlands. Snapping turtle relative abundance was best estimated with mean substrate depth, mean wetland depth, and minimum distance from roads. Painted turtle relative abundance was best estimated with the null model. We documented movement among wetlands for 22 snapping turtles (67%), including 10 females and 12 males. The probability of inter-wetland movement decreased with increased minimum distance from wetlands. Our results suggest that the focal turtle species readily used shallow, mucky wetlands with deep substrate and that increasing the density of wetlands could increase snapping turtle population connectivity. Managers could consider restoring a diversity of wetland types that result in reduced travel distance between wetlands and that collectively have characteristics conducive to multiple species.

Thermal Threats to Freshwater Mussels: An Empirical Stream Assessment

Freshwater mussels fulfill an important ecological role in aquatic ecosystems, but they currently face many threats, including thermal regime alteration. Thermal transformation of the aquatic environment is associated with climate change, land use alteration, and other pervasive anthropogenic global changes. To enhance our understanding of ecological thermal impacts, we combined extensive field measurements of temperature in the stream water column and substrate depths (5 and 15 cm) at sites where mussels occur, measures of abundance and species richness for mussels and fish, and thermal tolerance knowledge for mussels and fish to generate a comprehensive assessment of the potential threats mussels face as temperatures continue to rise as a result of global change. Mean summer (June–August 2010–2012) temperatures at mussel-occupied sites in the upper Tar River basin of North Carolina, USA, ranged from 16.2 to 34.7 °C. The mean temperature from the hottest 96 h at each site ranged from 23.5 to 31.5 °C. At 80% of sites, a period of moderate drought coincided with the hottest 96 h period. Temperature threshold exceedance durations indicated that chronic, combined chronic/acute, and acute freshwater mussel thermal tolerance thresholds (i.e., 28 °C, 30 °C, and 33 °C, respectively) based on laboratory exposures of glochidia (larvae) and juveniles were commonly exceeded. Water temperatures exceeded 28 °C for at least 24 h at 55% of sites and for at least 96 h at 35% of sites, and they exceeded 30 °C for at least 24 h at 15% of sites. We quantified a thermal buffering effect of the substrate that may be protective of mussels. There was a mean difference of 0.5 °C between the water column and the upper substrate (5 cm) and a mean difference of 0.9 °C between the water column and the lower substrate (15 cm). Maximum differences of up to 5.5 °C between the water column and the upper substrate and 11.5 °C between the water column and the lower substrate were observed. Our models estimating the relation between the water column and substrate temperatures more realistically characterize ambient temperature exposures and have widespread implications for mussel conservation and climate change risk assessment in similar streams. Freshwater mussels currently exist on the edge of their thermal limits, but their abundance and species richness cannot be explained by temperature patterns alone. Fish species richness was related to the thermal regime, indicating that species interactions may be an important driver of freshwater mussel responses to global change.

Investigating the Climate Mitigation Performance of A Green Roof System in the Flint Hills Ecoregion, USA

Rooftop green infrastructure enhances sustainable urban development by reducing atmospheric CO2 as carbon is sequestered in plants and substrates. However, it is uncertain what substrate types, depths, and plant combinations sequester the greatest amounts of carbon in green roofs across different ecoregions, including the U.S. Great Plains. This research sought to evaluate carbon sequestration potential of two experimental green roof beds of 10 cm (4 in) and 20 cm (8 in) and two substrate types in Manhattan, Kansas, USA. Microbial and root biomass and their interactions were measured as early indicators of changes in soil organic carbon (SOC). Soil and root biomass samples were taken from beds of two depths with two substrates (K and R) and three plant communities (all sedum, sedum and grass, and native grasses and forbs) for a total of 48 plots. Microbial biomass was measured by phospholipid fatty acids (PLFA) analysis in 2019 and root biomass in 2020. Root biomass and microbial biomass was greater in native grass in shallower beds. Shallower beds can partially offset the need for deeper beds and should perform well in mitigating climate change if beds are irrigated during very dry periods.

Machine Learning and Deep Learning Guided Assessment of Groundwater Reservoir Hydrodynamic Parameters: A Case Study of The El Haouz Aquifer

The Plio-Quaternary aquifer in the EL-Haouz-Mejjate region of Morocco is critical for water supply, necessitating accurate characterization for sustainable management. This study pioneers machine learning (ML) and deep learning (DL) techniques to elucidate the aquifer’s properties. Supervised algorithms, including random forest, regression, support vector machines, Gaussian process regression and neural networks, are trained on available hydrogeological data. Diverse features capture complex input-output relationships to predict key hydrodynamic factors like hydraulic conductivity and transmissivity fields. Aquifer architecture attributes, including substratum depth, thickness, and height, are also estimated. Model outputs are validated with field measurements, demonstrating promising accuracy. Enhanced hydrodynamic insights improve the conceptual model and groundwater flow modeling confidence. Uncertainties are reduced through this data-driven approach, enabling optimized aquifer management. Overall, this work shows how useful it is to combine ML and DL with traditional hydrogeology in order to get a better understanding of complicated aquifer systems. The techniques pioneered provide a pathway for sustainable management of this vital water resource.

Structure and Functions of Green Roof and Its Development in Urban Areas, China

The green roof is an environmentally friendly design, which is important for sustainable development and improvement of resilience in urban areas. This paper offers a systematically review of the classification, material selection, functionality, limiting factors of green roofs, and provides suggestions. The green roof is classified into intensive, extensive and semi-intensive ones according to the substrate depth and vegetation type. Its basic structure includes vegetation, substrate, filter, drainage, protection, anti-root, insulation and waterproofing layers from top to base. Among which, vegetation, waterproofing and drainage are vital layers to decide the roof efficient. The factors such as light, temperature and humidity conditions of the site are vital for determination of vegetations for a green roof. Green roofs provide benefits for urban areas via saving energy, reducing stormwater runoff and improving aesthetic. Roof load-bearing, seepage, survival of vegetations and support from all sectors are the main issues for the development of green roofs at current stage.

Microstructure and Mechanical Properties of Fe-Based Alloy Coatings Fabricated by Laser Cladding

The Fe-based alloy coating was prepared on the surface of 25Cr2Ni4MoV steel substrate by laser cladding. The microstructure, microhardness, shear strength, friction and wear properties of the laser cladding coating were systematically studied. The results show that a good metallurgical bond has been formed between Fe-based alloy coating and substrate. The laser cladding layer is a typical dendritic crystal, which is composed of light gray and dark gray phases. The shear strength displacement curve shows the typical characteristics of brittle fracture, with an average shear strength of 280.83 MPa. The average dry friction coefficient, wear track depth and average wear volume of laser cladding Fe-based alloy coatings are (0.45 ± 0.01), (26 ± 3) μm and 0.066615 m3, respectively. The average dry friction coefficient, wear track depth and average wear volume of 25Cr2Ni4MoV substrate are (0.60 ± 0.01), (39 ± 3) μm and 0.13085 m3, respectively. The laser cladded Fe-based alloy coating exhibits much better wear resistance than the steel substrate, and the shear strength of the coating displays its potential for the application in the service environment of shear stress.

Colonization–persistence trade-offs shape changes on vegetation island community assembly in campo rupestre under fire disturbance

We studied neglected island plant communities on rock outcrops (vegetation islands or patches) that harbor many endemic species. We assessed how the post-fire habitat conditions (factor related to habitat filtering), the patch area and substrate depth (factors related to resource availability and environmental filtering), and the patch distance (spatial factor related to dispersal limitation) shape the plant community attributes, life forms and persistence–reproduction trade-offs in a campo rupestre in the Chapada Diamantina, Brazil. Two years after a wildfire, we sampled 82 vegetation islands in two habitat conditions based on fire disturbance (burned and unburned). We verified high plant mortality caused by wildfire. All succulent and desiccation-tolerant chamaephytes died, but while the desiccation-tolerant chamaephyte recolonized burned vegetation islands by seedling recruitment, the succulent chamaephyte lack regeneration after disturbance, demonstrating their vulnerability to fire disturbances. The post-fire recovery was driven by obligate resprouters (hemicryptophytes and phanerophyte), post-fire colonizers (therophytes and phanerophytes), facultative seeders (phanerophytes), and desiccation-tolerant obligate seeders (chamaephytes). Despite the similar species richness between burned and unburned vegetation islands, the fire-habitat conditions determined changes in species composition and persistence–reproduction trade-offs. We demonstrated that random processes related to the colonization-survival and persistence–reproduction trade-offs can be a strong biotic factor shaping vegetation islands on rocky outcrops beyond environmental filtering and dispersal limitation. Our study is the first to investigate the fire effects on vegetation islands in rock outcrops and reveal the desiccation-tolerant obligate seeder as a novel post-fire regeneration strategy, that has a central role in the vegetation island community assembly.

Stress tolerant species are keys to plant communities success on extensive green roof: an experimental test of CSR strategy dynamic

Selecting appropriate native plant species to ensure the resilience of plant communities and ecosystem services on extensive green roofs is a challenge. Plant functional strategy models provide a useful framework for identifying plant characteristics that promote plant success on green roofs, and for generalizing results obtained with a limited number of species to a global flora. We analysed the dynamics of floristic composition and CSR strategies of seeded plant communities on experimental extensive green roofs under different stress conditions (substrate depths and fertilization treatments) at early establishment (4 years). Floristic composition evolved strongly over four years, with a significant reduction in species richness and equitability due to the increasing dominance of the stress-tolerant Sedum album. CSR strategies shifted from initial communities co-dominated by C and R strategies to communities largely dominated by S strategy four years later. Changes in plant communities strategy were modulated by substrate depth, with a higher increase in S strategy under more stressful conditions. At the installation of vegetation, the dominant factor discriminating CSR composition was fertilization supply. Substrate depth emerged as the primary factor determining CSR strategy after four years of plant community establishment. Our study supports the pattern that stress-tolerant species tend to rapidly dominate plant communities on extensive green roofs and suggests that native species selection for implementing analogous habitat on extensive green roofs, in a temperate climate, should primarily focus on natural habitats composed of stress-tolerant species. A mix of different functional strategies can be favourable to vegetation success on green roofs with environmental heterogeneity.

Diurnal greenhouse gas emissions and substrate temperatures from blue-green roofs in north-eastern Italy during a dry-hot summer season

Covering building rooftops with vegetation [Green roofs (GRs)] holds promise for lowering building temperatures, reducing stormwater runoff, and providing other ecosystem services, but it is unclear how this will impact greenhouse gas (GHG) emissions. The latter may also be influenced by vegetation type, substrate depth, and irrigation regime and we sought to test this by comparing daytime GHG emissions (i.e., CH4, CO2, and N2O) and daily substrate temperatures in 48 GR microcosms in North-eastern Italy during a dry-hot summer season (June to September). Four vegetation types (Sedum mixture, cold season grasses, warm season grasses, or wildflowers), two substrate depths (8 cm or 14 cm), and two irrigation levels (1 or 2 mm d−1) were evaluated, for a total of 16 treatments with 3 replicates. We found that vegetation type had a significant effect on temperature [average temp. of 24.8 °C (Sedum) vs 25.5 °C (warm season grasses)] and CH4, CO2, and N2O emissions. While all vegetation types had net CO2 emissions (median values from 147 to 671 mg m−2 h−1) and net N2O uptake (median values from -0.06 to -0.28 mg m−2 h−1), CH4 flux had net negative values (capture) only in microcosms with wildflowers (-0.07 mg m−2 h−1), whereas other treatments had a median CH4 emissions of 0.09 mg m−2 h−1. Substrate depth significantly affected CO2 and N2O fluxes with deeper substrate leading to higher CO2 emission (+ 60.7%) and greater N2O uptake (+ 30.8%). Irrigation level only significantly influenced N2O fluxes with 2 mm irrigation resulting in higher fluxes (-0.20 mg m−2 h−1) than 1 mm irrigation (-0.09 mg m−2 h−1). Our study suggests that under heat induced plant-stress conditions, GRs can improve N2O and CH4 capture but might increase the emissions of CO2 fixed by plants in the previous years in the substrate and that vegetation type and substrate depth can significantly alter emissions and are thus important design parameters.

Coexistence of megabenthic assemblages and artisanal fishers: The case of Cap de Creus Marine Protected Area (North-Western Mediterranean Sea)

Artisanal fisheries, although considered less harmful, can still endanger marine ecosystems, especially in areas with long-standing tradition. In Cap de Creus, where artisanal fisheries has likely occurred for centuries, the status of benthic communities in fishing grounds was poorly understood. Through collaboration with local fishers, the benthic assemblages in three artisanal fishing grounds within Cap de Creus Marine Protected Area (MPA) were studied. Using video transects recorded by a remotely operated vehicle (ROV), the diversity and distribution of species were analysed in relation to substrate type, slope, and depth. The study also assessed the impacts on these communities by examining marine litter, lost fishing gear, and the condition of gorgonian populations. The findings identified three megabenthic assemblages and revealed higher fishing pressure and impact in the Maça d’Oros area, likely due to multiple fishing guilds converging. However, the study demonstrated lower impact in MPAs compared to unprotected Mediterranean areas, highlighting the importance of coastal management.

Evaluation of native herbaceous plants for green roof applications in Istanbul

Green roofs are important components by providing several benefits in urban environments. To achieve these benefits, appropriate plant selection is crucial. Therefore, a study was conducted to evaluate the plant diversity of the Istanbul and Marmara Region of Turkey for potential native suitable plants for green roofs. In this regard, suitable plants for extensive green roofs were investigated among international studies. Detected plant species were compared to taxa in the A2 grid square of Flora of Turkey P.H. Davis (1965-1985). At the second stage of the study, among listed plants, specific open field measurements were performed on 5 selected native plant species including Anthemis tinctoria L., Euphorbia myrsinites L., Prunella vulgaris L., Stachys thirkei C.Koch and Veronica chamaedrys L., which were collected from their natural habitats in Marmara region. The selected plants were placed in two different substrates, each comprising a mixture of lava rock or pumice with municipal waste compost in a volume ratio of 8:2. Measurements, including plant growth index, chlorophyll fluorescence, plant coverage ratio, and plant taxa survival, were conducted over a study period of 53 weeks. All the plant species have reached the phenomenological stage of blossoming in the study. The highest survival rate was observed on Veronica chamaedrys grown in pumice substrates treatments. Prunella vulgaris well adapted to the green roof environment. Despite the number of individual losses, Stachys thirkei exhibited a relatively higher revitalization ability, while Euphorbia myrsinites demonstrated greater drought resistance. A.tinctoria failed to adapt to the limited green roof substrate depth.

Substrate moisture variations of extensive green roofs with different structural configurations in a semi-arid region: Observational data and dynamic simulation

Substrate moisture condition is crucial for hydrological performance, water management and plant survival of green roofs. To date, the behaviour of long-term substrate moisture of green roofs in various climate regions has not been well understood. In this study, 24 months continuous field monitoring of substrate moisture content within nine extensive green roof modules with varies structural configurations was conducted to investigate the impacts of structural configurations and meteorological factors on substrate moisture content, and identify the key parameters for simulating the long-term substrate moisture dynamics. Results showed that green roofs planted with SedumSpectabilehave the highest mean volumetricwater content (VWC) (0.12–0.15 m3/m3) compared to other plant species considered. Green roofs with 5-cm substrate depth had lower mean VWC (0.07–0.08 m3/m3) than other substrate depths. The average substrate moisture loss rate of green roofs in summer and autumn seasons was 1.35 and 1.22 mm/day, respectively, which was higher than the spring (0.73 mm/day) and winter (0.64 mm/day) seasons for 2021. There were significant differences in mean VWC of green roofs among substrate material types. The mean VWC of green roofs was gradually enhanced from 0.12 to 0.14 m3/m3 as the substrate depth increased from 5 cm to 15 cm. The differences of mean VWC among vegetation types were all extremely significant (p < 0.001). The relative humidity was the most significant influencing factor on the average VWC level (correlation coefficient r = 0.42), with antecedent dry weather period (ADWP) had less significant effects on substrate VWC (r = 0.33), and followed by precipitation depth (r = 0.27). However, there was no significant relationship between air temperature and average VWC level of green roofs as well as total solar radiation. Nash-Sutcliffe efficient (NSE) values of the model simulations ranged from 0.70 to 0.81, and the mean absolute relative error (MAE) values ranged from 1.25 to 2.36, which indicated the model can adequately simulate the long-term substrate moisture content dynamics of green roofs. The crop coefficient and maximum water holding capacity of the substrate were the key parameters affecting long-term moisture content simulation of green roofs. These results could provide scientific suggestions for selecting suitable structural configuration to enhance water holding capacity of extensive green roofs in arid climates.

Dynamics of black soldier fly larvae composting – Impact of substrate properties and rearing conditions on process efficiency

Inadequate organic waste management have detrimental impact on the environment and on public health. Black soldier fly (BSF) larvae composting is a biological treatment for biodegradable waste that align with circular economy principles. The bioconversion efficiency of bio-waste into larval biomass is influenced by various factors, such as substrate type and the process parameters employed in the larval rearing process. In this study, the influence of these parameters on survival, material reduction (Mat.Red), waste-to-biomass conversion efficiency (BCE) and larval yield per rearing unit was investigated through two sets of experiments. In Experiment 1, the impact of larval density in five distinct rearing substrates was evaluated, while the effect of larval feed dose and substrate depth was assessed in Experiment 2, using a model substrate (dog food). In Experiment 1 it was found that higher larval density lead to an increase in BCE and larval yield, up to a threshold (around 6.25 larvae cm−2). Surpassing this threshold led to the production of smaller larvae, while the yield remained relatively consistent. In Experiment 2 it was found that supplying the substrate in a shallow layer (1–1.5 cm depth) and providing a low feed dose (0.1 g volatile solids (VS) larva–1) led to higher BCE and Mat.Red, albeit with a reduced overall yield per unit. Increasing feed load and substrate depth reduced the conversion efficiency, Mat.Red and larval survival. This study enhances the understanding of the effect of various process parameters used in the BSF larvae treatment, and how they interrelate.

Coexistence and Succession of Spontaneous and Planted Vegetation on Extensive Mediterranean Green Roofs: Impacts on Soil, Seed Banks, and Mesofauna

Extensive green roofs are well known to improve the urban environment, but in the Mediterranean regions, dry climatic conditions pose the problem of their sustainability when no irrigation is applied. After planting or sowing in 2012, 18 local Mediterranean plant species on different types of exposure and substrate in a non-irrigated extensive green roof in Avignon (South-Eastern France), the physico-chemical characteristics of the soil, winter and spring soil seed banks, soil mesofauna and initially sown, planted, or spontaneous vegetation expressed on the surface were studied from 2013 to 2020. In 2020, significant differences related to the exposure conditions (shade/sun) and, to a lesser extent, to the depth of substrate used (5 cm/5 cm or 10 cm with a water retention layer) were found. The deeper plots in the shade have significantly higher soil fertility, cover, and vegetation height. However, the plots in the sun have higher moss cover, planted or sowed vegetation abundance, and springtail abundance. By 2020, more than half of the initially sown species had disappeared, except for several planted perennials and short-cycle annual species. On the other hand, a significant increase in the species richness of spontaneously established species was measured over time. In the absence of a permanent and transient seed bank for the sowed and spontaneous species, the plant community is then mostly dependent on species flows via the local surrounding seed rain. Planting perennial species (Sedum spp., Iris lutescens), followed by spontaneous colonization of species present in the vicinity of the roof would then represent a more efficient strategy for the persistence of extensive non-irrigated green roofs in Mediterranean environments than sowing a species-rich local Mediterranean seed mixture dominated by annual species.

Fit by design: Developing seed–substrate combinations to adapt dike grasslands to microclimatic variation

Abstract Sowing is a well‐established restoration technique to overcome dispersal limitation. Seed mixtures adapted to certain environmental conditions, like substrate or microclimate, are most effective to achieve functional communities. This is especially important if the restored vegetation has to protect critical infrastructure like roadsides and dikes. Here, an improved seed–substrate combination will secure slope stability, make restorations more effective and generate species‐rich grasslands. A full‐factorial field experiment addressed this topic on a dike at River Danube in SE Germany in 2018–2021. Within 288 plots, we tested three sand admixtures, two substrate depths, two seed densities and two seed mixture types (mesic hay meadow and semidry calcareous grassland) in north and south exposition and measured the recovery completeness by calculating the successional distance to reference sites, the persistence of sown species and the Favourable Conservation Status (FCS) of target species. Overall, the sown vegetation developed in the desired direction, but a recovery debt remained after 4 years, and some plots still showed similarities to negative references from ruderal sites. In north exposition, hay meadow seed mixtures developed closer to their reference communities than dry grassland mixtures to their reference. In south exposition, the sown communities established poorly, which might be due to a severe drought during establishment. This initial negative effect remained over the entire observation period. Sand admixture had a slightly positive effect on target variables, while the tested substrate depths, seed densities and seed mixture types had no effects on species persistence or FCS. Synthesis and applications: Site‐adapted seed mixtures make restoration more effective, while applying several seed–substrate combinations might foster beta diversity. Furthermore, additional management efforts are recommended, as they might be necessary to reduce the recovery debt, as well as re‐sowing after unfavourable conditions like droughts.

Evaluating the effectiveness of spontaneous vegetation for stormwater mitigation on green roofs

Green roofs can reduce stormwater runoff in urban areas by capturing rainfall. The extent of this capture is partially influenced by vegetation type and cover, which can be manipulated to optimise run-off reduction. However, in the absence of routine maintenance, planted green roof vegetation is often replaced by ‘weedy’ spontaneous species with unknown rainfall retention qualities. To better understand the role of spontaneous vegetation in green roof stormwater mitigation, we undertook a 100-day rainfall simulation involving 14 plant species that occur spontaneously on green roofs in Mediterranean-type climates. Green roof modules were filled with either 7 cm (shallow) or 14 cm (deep) substrate. The substrate was either left bare or sown with the spontaneous species community, which established approximately 100 % cover prior to the beginning of the rainfall simulation. During the simulation, modules were subjected to a “dry” and then a “wet” rainfall phase, each based on historical climate records from Melbourne, Australia. The “dry” treatment replicated the timing and depth of the driest rainfall period on record, while the “wet” treatment applied rainfall depths randomly selected from the 90th, 95th, and 99th percentiles of recorded rainfall. Rainfall retention, evapotranspiration, time to initiation of runoff and soil water content was measured for 17 rainfall events. Spontaneous vegetation cover and both species and functional diversity were measured at the end of each rainfall phase, and biomass was measured at the end of the wet phase. During the dry phase, modules with spontaneous vegetation cover retained 88 % of applied rainfall regardless of substrate depth and had 6 % greater retention than bare substrate. During the wet phase, deep substrate modules with spontaneous vegetation cover had 30 % greater retention than other treatment combinations. At the end of the wet phase, spontaneous vegetation in deep substrate had 42 % greater biomass, 19 % greater coverage and more than twofold greater functional richness than in shallow substrate. These findings demonstrate that spontaneous vegetation can increase stormwater retention on green roofs relative to bare substrate and have similar retention performance to commonly utilised species. However, the extent to which stormwater mitigation on green roofs is enhanced by spontaneous vegetation is dependent on factors that are more important for rainfall retention, such as substrate depth and rainfall patterns.

Use of a Dielectric Sensor for Salinity Determination on an Extensive Green Roof Substrate.

The irrigation of extensive green roofs with recycled or saline water could contribute to the conservation of valuable drinking water supplies. In such cases, the continuous monitoring of substrate electrical conductivity (ECsw) is of immense importance for the sustainable growth of the plants growing on the green roof. The present study aimed to estimate the ECsw (pore water EC) of an extensive green roof substrate in lysimeters with the use of the WET-2 dielectric sensor. Half of the 48 lysimeters that simulated extensive green roofs had a substrate depth of 7.5 cm, while the other half had a 15 cm substrate depth. The warm season turfgrass Paspalum vaginatum 'Platinum TE' was established at the lysimeters, and during the summer period, it was irrigated every two days at a rate of 14 mm with NaCl solutions of various electrical conductivities (ECi): (a) 3 dS m-1, (b) 6 dS m-1, and (c) 12 dS m-1, while potable water of 0.3 dS m-1 ECi served as the control. The relation between bulk electrical conductivity, σb, and bulk dielectric permittivity, εb, of the substrate was observed to be linear for all ECi levels up to σb values of 2-2.5 dS m-1. The ECsw was predicted by employing the salinity index method which was modified to be applied to the particular case of a green roof substrate. Knowing the salinity index and organic portion (%, v/v) for a given green roof substrate, we could calculate the ECsw. It was found that the use of the salinity index method predicts reliably the ECsw up to 10-11 dS m-1, while the method overestimates ECsw at very low levels of electrical conductivity.

Response of Spontaneous Plant Communities to Sedum mexicanum Cover and Water Availability in Green Roof Microcosms

Lack of maintenance can lead to ‘weedy’ spontaneous vegetation on green roofs. Aspects of green roof design, including substrate depth and roof height, have been shown to influence the composition of spontaneous vegetation. In drier climates, Sedum species are often planted on shallow substrate ‘extensive’ green roofs and irrigated during summer to maintain cover. However, the response of spontaneous vegetation to Sedum cover and water availability is unclear. Understanding this relationship could help minimise maintenance and maintain Sedum vegetation cover. We hypothesised that increasing Sedum (Sedum mexicanum) cover and reduced water availability would reduce the abundance, biomass, species and functional richness, and the community weighted mean specific leaf area (SLA; CWM by abundance) of spontaneous plant communities. We conducted a 10-month experiment in green roof microcosms planted with S. mexicanum (0%, 25%, 50%, 75% and 100% total cover), subjected to a well-watered or water-deficit irrigation treatment, and sown with a mix of 14 plant species that commonly occur as spontaneous on green roofs. We measured spontaneous species abundance, community biomass, and functional traits (specific leaf area, leaf dry matter content, and relative growth rate), and calculated species and functional richness. Increasing S. mexicanum cover reduced spontaneous species abundance and species and functional richness but did not affect community biomass. Species richness was affected by the interaction of S. mexicanum cover and watering treatment and was greatest in well-watered microcosms with 0% S. mexicanum cover. Increased water availability increased spontaneous plant biomass but did not affect functional richness. The SLA of spontaneous communities was affected by the interaction of S. mexicanum cover and watering and was significantly greater in well-watered treatments where S. mexicanum cover was &lt;100%. Therefore, maximising Sedum cover and limiting water availability on green roofs will likely limit the abundance, biomass, and diversity of spontaneous vegetation. Conversely, for green roofs where substrate is left to be naturally colonised, increasing water availability could encourage establishment and increase functional richness of spontaneous vegetation.

PO-05-100 DETECTION OF THE CRITICAL SUBSTRATE FOR VENTRICULAR TACHYCARDIA ABLATION WITH THE COMBINED IMAGE OF TC-99M SCINTIGRAM AND LATE IODINE ENHANCEMENT CT

Late potentials (LPs) are the important target for ventricular tachycardia(VT) abltion. However, LPs sometimes cannot be observed sufficiently because of intramural localization of VT substrates. Efficacy of CT for prediction of VT substrates even in intramural layer has been reported. On the other hand, Tc-99m scintigram has been reported to determine the viability of myocardium. The uptake of Tc-99m scintigram could quantify the viability of VT substrates and predict the localization of critical VT substrates such as LPs. Moreover, combination of CT and Tc-99m scintigram could show intramural VT substrates. We evaluated the relationship between the localization of LPs and uptake rate of Tc-99m scintigram. Moreover, we evaluated VT substrates with combined image of scintigram and CT. In eight patients (age, 67.5±8.6 years ; left ventricular(LV) ejection fraction, 26.0±8.7%) with ischemic cardiomyopathy and VT, electroanatomical map (EAM) and Tc-99m scintigrafic image of LV were obtained and were divided into twenty segments. LPs were determined as isolated potentials after QRS and were evaluated in EAM. The relationship between LPs and scintigrafic characteristics was evaluated in total of 160 segments. Electrocardiogram gated CT was performed and late iodine enhancement(LIE) was recorded 8 minutes after administration of contrast media. LPs were recorded in 59 segments. According to the Tc-99m uptake rate, cut off value 35% was set for the prediction of the location of LPs with ROC curve. LPs were observed in the lower scintigram perfusion segments with ≤35% uptake rate (n=61) more than the segments with >35% uptake rate (n=99) with statistical significance (78.6% vs 11.1% p<0.0001). With this cutoff value, we performed another VT ablation with intramural substrate. EAM revealed the exit site of VT circuit from endocardium and the existence of intramural substrate (Fig.A). Low Tc-99m uptake area observed around the apical aneurysm and made the borderline between the basal normal voltage area (Fig.B). LIE showed the transmural damaged tissue on the apical aneurysm and the intramural damaged tissue of mid anterior wall(Fig.C). This border zone of Tc-99m uptake and intramural LIE was similar to the exit site of VT circuit. Long cauterization on this area terminated VT. Lower perfusion area of Tc-99m scintigram could be utilized to predict VT substrates in ICM patients and combination of LIE of CT could add the information of the depth of the VT substrate.

Bidirectional flow of two-dimensional dusty plasma under asymmetric periodic substrates driven by unbiased external excitations

Collective transport properties of a one-dimensional (1D) asymmetric periodic substrate modulated two-dimensional (2D) dusty plasma driven by an unbiased sinusoidal excitation force are investigated using Langevin dynamical simulations. It is discovered that by changing the amplitude and frequency of the unbiased sinusoidal external excitations, as well as the depth of the 1D asymmetric periodic substrate, both the direction and speed of the persistent particle flow can be adjusted, i.e., both the flow rectification and its reversal of the ratchet effect of the steady drift motion for particles are achieved using various excitations. For the studied 2D dusty plasma under the 1D asymmetric periodic substrate, when the amplitude of the excitation increases from zero, the magnitude of the overall drift velocity increases from zero to its first maximum in the easy direction of the 1D asymmetric periodic substrate, next decreases gradually back to zero, and then increases from zero to its second maximum in the hard direction of the 1D asymmetric periodic substrate before finally gradually decaying. It is found that, as the frequency of the excitation and the depth of the 1D asymmetric periodic substrate change, the maximum overall drift velocity also varies, exhibiting a similar variation trend as that for the change of the excitation amplitude. The observed ratchet effect in both the easy and hard directions of 1D asymmetric periodic substrate for 2D dusty plasma is attributed to the combination of the spatial symmetry breaking of the 1D asymmetric periodic substrate and the inertial effects of particles, which is further confirmed by the three different presented diagnostics.