Local Site Conditions Research Articles

Dynamics of bacterial blight disease in resistant and susceptible rice varieties

Bacterial blight (X. oryzae pv. oryzae) is a serious disease in rice across the world. To better control the disease, it is important to understand its epidemiology and how key aspects of this (e.g. infection efficiency, and spatial spread) change according to environment (e.g. local site conditions and season), management, and in particular, variety resistance. To explore this, we analysed data on the disease progress on resistant and susceptible varieties of rice grown at four sites in the Philippines across five seasons using a combination of mechanistic modelling and statistical analysis. Disease incidence was generally lower in the resistant variety. However, we found no evidence that the primary infection efficiency was lower in resistant varieties, suggesting that differences were largely due to reduced secondary spread. Despite secondary spread being attributed to splash dispersal which is exacerbated by wind and rain, the wetter sites of Pila and Victoria in south Luzon tended to have lower infection rates than the drier sites in central Luzon. Likewise, we found spread in the dry season can be substantial and should therefore not be ignored. In fact, we found site to be a greater determinant of the number of infection attempts suggesting that other environmental and management factors had greater effect on the disease than climate. Primary infection was characterised by spatially-random observations of disease incidence. As the season progressed, we observed an emerging short-range (1.6 m–4 m) spatial structure suggesting secondary spread was predominantly short-range, particularly where the resistant variety was grown.

Construction of a regional model for the damping of strong ground movements for the baikal rift zone

The article is devoted to the study of physical characteristics (oscillation amplitudes and ground response spectra) from earthquakes for the Baikal rift zone. Determination of reliable parameters of possible earthquakes during engineering and geological surveys is necessary to ensure the seismic resistance of objects in order to prevent damage and loss of life. The attenuation model describes the dependence of ground motion characteristics on earthquake parameters, distance to the source, local site conditions. In this paper the model is built on the basis of regional catalogs of earthquakes.

Local site characteristics and earthquake ground motion parameters around the Nile River, south of Cairo, Egypt

Parameters related to local site conditions represent an essential information for earthquake hazard evaluation and seismic risk mitigation at any region. In this research, the authors determine the local site characteristics and seismic ground motions around the Nile River, south of Cairo City, Egypt. This area suffered from a moderate earthquake (Mw 5.8) on 12 October 1992 and influenced by a soil liquefaction. Furthermore, the area is covered by soft sediments with large thickness, which may amplify seismic waves and lead to more damage in the event of earthquakes occurrence.Microtremor survey was carried out at six liquefiable sites in the study area by array of seismic stations. The recorded data was analyzed by the Centerless Circular Array (CCA) method to infer the shear wave velocity (Vs). The dispersion curves yielded from this analysis cover frequency range from 2.3 to 13.5 Hz. An inversion process was applied to get the Vs profile. The obtained velocities were averaged at 30 m depth (Vs30) which in turn have been used for a soil classification and for calculating the bearing capacity of soil. The H/V spectral ratio method was used for an experimental estimation of the site predominant frequency and its corresponding amplitude of seismic waves. Moreover, seismic amplification was calculated using the shear wave velocities. The Peak Ground Acceleration (PGA) and seismic intensity (MMI) were calculated for the October 12, 1992, earthquake.The results reveal Vs30 values from 170 to 240 m/s. Soil Class D is predominant in the study area. The amplification factor ranges from 2.5 to 4.5, corresponding to predominant frequency from 0.5 to 1.4 Hz. The allowable bearing capacity ranges from 0.7 to 1.0 Kg/cm2. The PGA at the surface ranges from 0.16 to 0.4 g. The calculated seismic intensity (MMI) ranges from VII to VIII which are the same with those observed during the 12 October 1992 earthquake. The parameters estimated in this research may effectively contribute to the earthquake risk reduction in the study area.

An evaluation of seismic hazard and potential damage in Gaziantep, Turkey using site specific models for sources, velocity structure and building stock

Assessment of potential seismic risk and losses in urban environments is necessary for several purposes ranging from risk mitigation to city and regional planning. It is well known that loss estimation should be performed within an interdisciplinary setting involving earth sciences and engineering. Field experience from recent events worldwide shows that the spatial variability of seismic damage is due to the combined effects of earthquake source properties, local site conditions and structural characteristics. In this study, a scenario-based multi-input damage estimation framework in an urban region was utilized for the Gaziantep city center (southeastern Turkey) that is located in a region of high seismic hazard with no large events in the instrumental era. Initially, a thorough geological and seismo-tectonic assessment of the area was performed followed by estimation of two critical scenario events with moment magnitude (Mw) of 6.5 and 6.6 on nearby active faults. Then, a regional velocity model was compiled from regressions of existing regional geotechnical and seismic data in terms of the VS30 parameter. As the next step, field surveys for the assessment and classification of buildings in the study area were performed followed by vulnerability analyses. As the last step, the mean damage ratios were computed at 198 neighborhoods within the city center. The results indicate not only a high hazard but also high risk in the Gaziantep area due to the combination of close proximity to the faults along with local site effects and building fragilities.

Habitat quality and surrounding landscape structures influence wild bee occurrence in perennial wildflower strips

Perennial wildflower strips (WFS) are known to have positive effects on wild bees in intensively used agricultural landscapes. Little knowledge exists, however, about the drivers of wild bee occurrence and if Red List species also profit from this agri-environmental scheme (AES). Therefore, we studied wild bees on transects along 20 four- to five-year-old WFS and in 10 cereal fields without AES (CONTROL sites) in differently structured landscapes across Saxony-Anhalt (Germany). In addition to local site parameters, we measured parameters of landscape structure in a 1 km radius of the WFS and CONTROL sites. The overall species richness of wild bees (125 species in total, 23 on average), including numerous specialist and Red List species, indicates a high attractiveness of perennial WFS sown with 30 native forbs. In CONTROL fields, 11 bee species (on average only one) were found.The species richness and abundance of wild bees were positively affected by local site conditions of the WFS and CONTROL sites, such as the overall number of sown and spontaneous forbs, the amount of flower rewards of sown forbs available to pollinators (Pollinator Feeding Index), and negatively by the cover of grasses. Therefore, seed mixtures of future AES should comprise a high diversity of wildflower species relevant as pollen sources for wild bees. The share of Red List wild bee species was strongly influenced by the landscape context and increased e.g. with Shannon landscape diversity and the availability of non-forest woody habitats and water bodies in the 1 km surroundings. These results suggest that besides the establishment of high-diversity WFS, semi-natural habitat structures have to be promoted to preserve rare wild bees especially in structurally simple agricultural landscapes.

Simulation of Spatially Variable Artificial Earthquake: A Case Study of Different Site Conditions

Abstract The dynamic analysis of structures under seismic ground motions is a major issue in earthquake engineering. The seismic ground motions observed at the surface are variables in space and time. The main causes of this variability come from seismic waves propagation between the source and the site, and in particular the local geological site conditions. For this purpose, it is essential to consider all these factors of the spatial variability of seismic ground motion when representing seismic loading to be applied to any structure. Given the scarcity of real seismic records, many researchers suggest the use of artificial or synthetic seismic motions. The main objective of this study is the simulation of spatially variable artificial seismic motions by considering all fact of factors of the seismic spatial variability, especially site local conditions. In this sense, a simulation technique of spatially variable seismic motions is developed using the spectral representation method. By adopting the unconditional simulation approach, the target seismic motion in bedrock is defined by the Clough-Penzien spectral model and a specified coherency loss model. Then, the simulated ground motions in the bedrock are projected on the surface by considering amplification site effect. The results showed that the simulated artificial seismic motions are strongly conditioned by the local site conditions.

Plant mortality on ultramafic soils after an extreme heat and drought event in the Mediterranean area

AimsPlant mortality associated with the growing frequency and intensity of heatwaves and dry spells is increasingly occurring in various ecosystems worldwide. However, the impacts of extreme events on plant communities of ultramafic soils are still unknown. Here, we describe a first case of plant mortality on serpentine outcrops in Italy following a heat and drought event that occurred between autumn 2016 and summer 2017.MethodsMortality of perennial plants was assessed in thirty plots representing ten major serpentine areas along a SW-NE gradient, with the sparse vegetation of ultramafic soils. Statistical modelling was based on temperature and precipitation data and local site conditions.ResultsResponses of single species were largely different and not related to their taxonomic position, growth form or level of edaphic specialization for serpentine soils. Notably, obligate serpentine endemics were not less impacted than non-endemics. As expected, species mortality decreased with increasing chromosome number, suggesting higher tolerance and adaptive capacity in taxa of likely polyploid origin. Mortality increased with decreasing number of rainy days and duration of the heatwave and decreased with increasing distance from the Tyrrhenian coastline, reaching 60% in the southern and western areas with a Mediterranean climate. Local site conditions such as increasing soil depth and north-facing aspect significantly increased plant survivorship.ConclusionsOur findings show that extreme drought and heat can have a previously unrealized impact on ultramafic plant communities in the short term. Further studies should examine the recovery capacity and resilience of serpentine plants, together with the long term effects.

A Comparative Study on Soil Stabilization Relevant to Transport Infrastructure using Bagasse Ash and Stone Dust and Cost Effectiveness

Soft ground improvement to provide stable foundations for infrastructure is national priority for most countries. Weak soil may initiate instability to foundations reducing their lifespan, which necessitates the adoption of a suitable soil stabilization method. Amongst various soil stabilization techniques, using appropriate admixtures is quite popular. The present study aims to investigate the suitability of bagasse ash and stone dust as the admixtures for stabilizing soft clay, in terms of compaction and penetration characteristics. The studies were conducted by means of a series of laboratory experimentations with standard Proctor compaction and CBR tests. From the test results it was observed that adding bagasse ash and stone dust significantly upgraded the compaction and penetration properties, specifically the values of optimum moisture content, maximum dry density and CBR. Comparison of test results with available data on similar experiments conducted by other researchers were also performed. Lastly, a study on the cost effectiveness for transport embankment construction with the treated soils, based on local site conditions in the study area of Assam, India, was carried out. The results are analyzed and interpreted, and the relevant conclusions are drawn therefrom. The limitations and recommendations for future research are also included. Doi: 10.28991/cej-2021-03091771 Full Text: PDF

Ecological memory and regional context influence performance of adaptation plantings in northeastern US temperate forests

Abstract Species distribution models predict shifts in forest habitat in response to warming temperatures associated with climate change, yet tree migration rates lag climate change, leading to misalignment of current species assemblages with future climate conditions. Forest adaptation strategies have been proposed to deliberately adjust species composition by planting climate‐suitable species. Practical evaluations of adaptation plantings are limited, especially in the context of ecological memory or extreme climate events. In this study, we examined the 3‐year survival and growth response of future climate‐adapted seedling transplants within operational‐scale silvicultural trials across temperate forests in the northeastern US. Nine species were selected for evaluation based on projected future importance under climate change and potential functional redundancy with species currently found in these ecosystems. We investigated how adaptation planting type (‘population enrichment’ vs. ‘assisted range expansion’) and local site conditions reinforce interference interactions with existing vegetation at filtering adaptation strategies focused on transitioning forest composition. Our results show the performance of seedling transplants is based on species (e.g. functional attributes and size), the strength of local competition (e.g. ecological memory) and adaptation planting type, a proxy for source distance. These findings were consistent across regional forests but modified by site‐specific conditions such as browse pressure and extreme climate events, namely drought and spring frost events. Synthesis and applications. Our results highlight that managing forests for shifts in future composition represents a promising adaptation strategy for incorporating new species and functional traits into contemporary forests. Yet, important barriers remain for the establishment of future climate‐adapted forests that will most likely require management intervention. Nonetheless, the broader applicability of our findings demonstrates the potential for adaptation plantings to serve as strategic source nodes for the establishment of future climate‐adapted species across functionally connected landscapes.

Conifer Establishment and Encroachment on Subalpine Meadows around Mt. Baker, WA, USA

The subalpine ecotone is experiencing significant changes in habitat availability and connectivity as a result of climate change. The conversion of meadow habitats to forests has been observed in many mountainous regions. Rates of conifer encroachment into meadows appears to have increased in the 20th century, but the patterns of conifer establishment seem highly variable over both space and time. To understand how and why these changes vary temporally and spatially in the Pacific Northwest, we collected cross-sections and whorl counts from conifers along four transects in subalpine meadows around Mt. Baker, Washington. We quantified the relationships between temporal patterns of conifer establishment and a suite of climate variables, and between spatial patterns of conifer density and microsite characteristics. Our results show that establishment occurred in pulses throughout the 20th century, with greater establishment on drier sites during periods of greater precipitation, and greater establishment on wetter sites during periods of higher temperatures. We found that April precipitation and September temperature are particularly strongly correlated with establishment rates, suggesting that the best conditions for conifer seedling establishment occur in years with the warmth and soil moisture needed for the growing season to start earlier or last longer. Within individual meadows, conifer seedling establishment was greater on convex surfaces and in areas with a higher percentage of Vaccinium cover. Our findings at Mt. Baker show that periods of conifer establishment occurred somewhat synchronously across multiple mountains in the region, but we also identified distinct spatial and temporal differences linked to local site conditions.

Evaluation of methods for connecting InSAR to a terrestrial reference frame in the Latrobe Valley, Australia

Deformation measurements from satellite-borne synthetic aperture radar interferometry (InSAR) are usually measured relative to an arbitrary reference point (RP) of assumed stability over time. For InSAR rates to be reliably interpreted as uplift or subsidence, they must be connected to a defined Earth-centred terrestrial reference frame (TRF), usually made through GNSS continuously operating reference stations (CORS). We adapt and compare three methods of TRF connection proposed by different studies which we term the single CORS RP (SCRP), plane-fit multiple CORS (PFMC), and the multiple CORS RP (MCRP). We generalise equations for these methods, and importantly, develop equations to propagate InSAR and GNSS uncertainties through the transformation process. This is significant, because it is important to not only estimate the InSAR uncertainties, but also to account for the uncertainties that are introduced when connecting to the CORS so as to better inform our interpretation of the deformation field and the limitation of the measurements. We then test these methods using Sentinel-1 data in the Latrobe Valley, Australia. These results indicate that differences among the three TRF connection methods may be greater than their estimated uncertainties. MCRP appears the most reliable method, although it may be limited in large study areas with sparse CORS due to long wavelength InSAR errors and that gaps and/or steps may appear at the spatial limit from the CORS. SCRP relies on the quality of the single CORS connection, but can be validated by unconnected CORS in the study area. The PFMC method is suited to larger areas undergoing slow, constant deformation covering large spatial extents where there are evenly distributed CORS across the study area. Selecting an optimal method of TRF connection is dependent on local site conditions, CORS network geometry and the characteristics of the deformation field. Hence, the choice of TRF connection method should be carefully considered, because different methods may result in significantly different transformed deformation rates. We confirm slow subsidence across the Latrobe Valley relative to the vertical component of the ITRF2014, with localised high subsidence rates near open cut mining activities. Subsidence of ~ -6 mm/year is observed in the adjacent coastal region which may exacerbate relative sea level rise along the coastline, increasing future risks of coastal inundation.

Simulation of Spatially Correlated Multipoint Ground Motions in a Saturated Alluvial Valley

Based on Biot’s theory, the boundary element method, and spectral representation method, an effective simulation method for multiple-station spatially correlated ground motions on both bedrock and surface is developed, incorporating the spectral density function, coherence function, and site transfer function that consider both the wave scattering effect and the medium saturation. The accuracy and feasibility of the present method are validated by a typical numerical example. Our results indicate that the local site conditions and the saturation property of the medium significantly affect the multipoint spatially correlated earthquake ground motions, especially in the long-period range. It is necessary to use spatially varying ground motions with the rational consideration of local site effects and medium saturation as input during the seismic analysis of large-span structures.

Shallow soil effects for contrasting PGAs at nearby strong-motion stations during the 2017, Mj 5.2, southern Akita Prefecture earthquake

On September 8, 2017, an earthquake of Mj 5.2 occurred with the epicenter in southern Akita Prefecture, Japan, at 22:23 local time. According to the Japan Meteorological Agency (JMA), the focal depth was 9 km. Many strong-motion stations of K-NET and KiK-net recorded ground motions from the earthquake. The maximum horizontal vector peak ground acceleration (PGA) of approximately 136 cm/s2 was recorded at one of the KiK-net stations at an epicentral distance of about 8 km. However, despite being 37 km and 53 km far from the epicenter, two stations recorded PGAs of approximately 126 and 113 cm/s2, respectively, similar to that near the epicenter. Even though these PGAs are not rare, we found that the PGAs at the two sites strongly deviated from the median values suggested by a ground motion prediction equation (GMPE), while the nearby sites generally followed the GMPE. Available velocity models showed that shallow shear wave velocities, especially in the top 5 m, were lower (i.e., the soils were softer) at the two sites compared to those at their nearest neighboring sites. We compared the ratios of the PGAs and peak ground velocities (PGVs) at the two sites with respect to their neighboring sites for many earthquakes covering a wide range of magnitudes and azimuths. We found that the PGAs and PGVs at the two sites were systematically larger than those at the adjacent sites. Linear theoretical site amplifications using the available soil models gave peak frequencies around 6-8 Hz at the larger PGA sites. Bandpass-filtered records showed significantly larger PGAs around these frequencies at the larger PGA sites. The above results showed that local site condition is one of the major contributing factors to induce large PGAs. Furthermore, softer sites experience more substantial nonlinear site amplification than the stiffer sites when input motions exceed some threshold PGAs. This latter effect means that the softer sites can produce a variety of ground motion spectra. Nevertheless, the degree of damage to built structures depends on several factors, including the design and quality of construction. We expect that this study contributes to developing improved microzonation maps for earthquake disaster mitigation.

Diversity of Ants (Hymenoptera, Formicidae) in Two Forest Sites from Kabylia of Djurdjura, Northern Algeria

The current study deals with the diversity of ants (Hymenoptera, Formicidae) in Kabylia of Djurdjura. It has been carried out in two forest sites from the localities of Azeffoun and Assi-Youcef, Tizi Ouzou (northern Algeria). Two sampling methods were adopted: manual capture and pitfall traps. Various community metrics were used as key elements to assess ant biodiversity within the two study sites. They included the species richness, the relative abundance, the constancy, and the Shannon-Weaver and equitability indices. Our inventory allowed identifying 24 species belonging to 12 genera and three subfamilies, which are the Myrmicinae (58%), the Formicinae (34%), and the Dolichoderinae (08%). The highest species richness was registered for the two first subfamilies, while the subfamily Dolichoderinae dominated numerically. The Site of Azeffoun, which is more submitted to human activities, recorded higher values in the number of individuals, the species richness, and the Shannon-Weaver diversity index. However, the difference between the two sites consisted mainly of the rare species, such as Crematogaster laestrygon, Goniomma sp. and Palagiolepis sp., which were present in the Azeffoun site. The local site conditions certainly have played a key role in ant species occurrence within the two study areas. Azeffoun is more disturbed than Assi-Youcef, resulting in the recruitment of much more rare and accidental species in the first site. In contrast, the rate of accessory to omnipresent species is substantially higher in Assi-Youcef, which recorded a high species evenness. To the best of our knowledge, this is the first study to report the ant genus Formica in Kabylia of Djurdjura.

Seismic behaviors of free-spanning submarine pipelines subjected to multi-support earthquake motions within offshore sites

Due to the shortage of offshore seismic records and inhere difficulty in simulating artificial offshore ground motions, numerous existing works have been performed to investigate the seismic responses of free-spanning submarine pipelines, not only using onshore seismic records as inputs but also adopting uniform seismic excitations. These analytical schemes may result in severe misestimates of the seismic responses. In this content, this paper numerically investigates the seismic behaviors of a free-spanning submarine pipeline by using multi-support earthquake motions within offshore sites (MEMOSs) as inputs. The soil-pipe and water-pipe interactions are modeled using the nonlinear soil spring and added mass methods, respectively. The effects of spatially varying and overlying seawater are explicitly taken into account in the simulation of MEMOSs. The seismic behavior law of the free-spanning submarine pipeline under the synthesized MEMOSs is analyzed and summarized. Moreover, the impacts of the seismic excitation type, offshore seismic motion, coherence loss, local site condition and free span length on the Mises stress, vertical displacement and failure PGA of the submarine pipeline are examined and discussed comprehensively. Numerical results show that the middle and ends of free span are the dangerous regions; and the MEMOSs, coherence loss, local site condition and free span length have significant influences on the seismic responses and operational capacity of the pipeline. Based on the obtained results, some meaningful advices are recommended to the pipeline designers that (1) more attentions should be paid to the middle and ends of free span in the pipeline design; (2) the MEMOSs should be adopted as seismic inputs to accurately predict the seismic behaviors of pipelines; (3) the construction of submarine pipelines in soft clay and formation of large-dimensional free span are adverse for the safe operation of pipelines under earthquake actions, which should be avoided in engineering practice.

Storm Water Management

Over the past years, rapid growth due to urbanization and industrialization, the changes in Land over and land use patterns have resulted in permanent environmental pollution to the hydrological processes. The hydrological cycle in cities is seriously affected due to increasing impervious areas as a result of urban development which has enhanced the risk of urban flooding. The increase in the impermeable area decreases infiltration, increases the runoff and reduces the time of concentration. Hence, for a given amount of rainfall, greater flooding is generated. Understanding the scope and limitation of sustainable stormwater management techniques detailed literature review is carried out. Site suitability is based on spatial analysis of data like geomorphology, slope, recharge condition, landuse and Landover map. Then analyzing local site conditions possible techniques that could be used to manage stormwater runoff are recommended and conclusions are drawn on the same.

Data Driven Insight Into Fish Behaviour and Their Use for Precision Aquaculture

Aquaculture, or the farmed production of fish and shellfish, has grown rapidly, from supplying just 7% of fish for human consumption in 1974 to more than half in 2016. This rapid expansion has led to the growth of Precision Aquaculture concept that aims to exploit data-driven management of fish production, thereby improving the farmer's ability to monitor, control, and document biological processes in farms. Fundamental to this paradigm is monitoring of environmental and animal processes within a cage, and processing those data toward farm insight using models and analytics. This paper presents an analysis of environmental and fish behaviour datasets collected at three salmon farms in Norway, Scotland, and Canada. Information on fish behaviour were collected using hydroacoustic sensors that sampled the vertical distribution of fish in a cage at high spatial and temporal resolution, while a network of environmental sensors characterised local site conditions. We present an analysis of the hydroacoustic datasets using AutoML (or automatic machine learning) tools that enables developers with limited data science expertise to train high-quality models specific to the data at hand. We demonstrate how AutoML pipelines can be readily applied to aquaculture datasets to interrogate the data and quantify the primary features that explains data variance. Results demonstrate that variables such as temperature, wind conditions, and hour-of-day were important drivers of fish motion at all sites. Further, there were distinct differences in factors that influenced in-cage variations driven by local variables such as water depth and ambient environmental conditions (particularly dissolved oxygen). The framework offers a transferable approach to interrogate fish behaviour within farm systems, and quantify differences between sites.

Local conditions effects on seed germination of Hypericum balearicum L. in response to temperature

Temperature, which is one of the most relevant abiotic factors affecting seed germination, is strongly influenced by local site conditions. Here, we collected seeds of Hypericum balearicum, an endemic shrub of the Balearic Islands, from 11 sites of Mallorca. We investigated variations in final germination percentage (FGP), germination rate (t50) and germination timing (t0) of seeds from different provenances according to the local conditions of each location (here classified in mountain, coast and valley environment) under a range of temperature treatments (12–24 ºC). An environmental data logger was installed in three of the sites to determine the temperature variability for each environment. Hypericum balearicum germinates in the optimal temperature range of Mediterranean plants. FGP was neither affected by temperature treatments nor by the site of origin (environment). However, the coast environment showed higher t50 and t0 values in all temperatures tested compared to mountain and valley, especially at low temperatures compared to mountain environment and at low and high temperatures compared to valley environment. These differences among environments were consistent with the temperature parameters recorded in each environment. Overall, this study demonstrates the importance of taking into account local temperature conditions effects in germination in order to know how plants will respond to environmental changes.

The Influence of Tilia tomentosa Moench on Plant Species Diversity and Composition in Mesophilic Forests of Western Romania–A Potential Tree Species for Warming Forests in Central Europe?

Climate change challenges important native timber species in Central Europe. The introduction of non-native tree species originating from warmer climates is one option to make Central European forests compatible to global warming. This, however, requires an assessment of the species’ growth requirements, and of its impact on biodiversity in its native ranges. Silver lime (Tilia tomentosa), a moderately drought-tolerant, thermophilous tree species of South-eastern Europe is considered suitable for the future. Along three elevational transects in western Romania, we assessed the impact of changing climate and local site conditions on the abundance of this tree species and contrasted plant species diversity and composition of lime-dominated forests with mesophytic oak and beech forests. Local site conditions and disturbance histories shaped the distribution pattern of silver lime. When dominant, it reduced plant species diversity within stands due to its dense canopy. For shade-tolerant, mesophytic species, though, lime forests provided an additional habitat and extended their range into warmer environments. Thus, silver lime may have the potential as an admixed tree species forming a transitory meso-thermophilous habitat in the future. At the same time, silver lime may be limited under increasing drought frequency.

A full-scale field study on mitigation of environmental ground vibrations by using open trenches

Environmental ground vibrations induced by construction operations, machine foundations, vehicular and railway traffic may cause discomfort to the dwellers in their immediate vicinity and malfunctioning of sensitive equipment in nearby structures. Associated with technological development and rapid industrialization, undesired vibrations around the residential areas have increased. Hence, the isolation of those vibrations has become an important issue. Open trenches are mainly employed as wave barriers in mitigation of undesired vibrations. Recent studies have focused on the parameters affecting the vibration isolation performance of open and in-filled trenches. It is stated that screening effectiveness mainly depends on the type of the vibration source and geometric dimensions of open trenches along with the local site conditions. In the present study, a series of full-scale field experiments were conducted to identify the effects of governing parameters on efficiency. The amplitudes of ground vibrations, artificially generated on the site, were measured through highly sensitive accelerometers at different test configurations. It was concluded that the frequency of vibrations had more influence than the actual depth of the barrier on screening effectiveness. Better isolation can be achieved in a region close to the trench while the effectiveness decreases at great distances. In addition, the results were compared with those of recently reported in experimental studies.