Effects Of Burial Depth Research Articles

Effects of burial depth and water depth on seedling emergence and early growth of Scirpus planiculmis Fr. Schmidt

Seed burial and water regime are both crucial factors influencing seedling emergence and plant growth in wetlands and thus exert important effects on revegetation in degraded wetlands. We conducted a pot experiment to determine the effects of burial depth and water depth on the seedling emergence and growth of Scirpus planiculmis Fr. Schmidt. Seeds of S. planiculmis were buried at 0, 0.5, 1 and 2cm depths in plastic pots with non-sterilized sediment under exposed (−5cm), waterlogged (0cm) and submerged (5 and 10cm water depths relative to sediment surface) water regimes. The results showed that the percentage of seedling emergence at a burial depth of 0cm was enhanced under 10cm and 5cm water depths (78.89% and 81.37%, respectively) in comparison to the results under −5cm and 0cm water depths (0 and 2.22%, respectively). Seedlings did not grow through the water to the surface and no tuber formed when covered by 10cm of water. The total biomass per seedling was generally higher at 0.5cm or 1cm burial depths than that at other burial depths. The tuber number per seedling was highest at a 0.5cm burial depth, while the value was lowest at a 0cm burial depth. Our results provide valuable guidance for the establishment of S. planiculmis from seeds in wetland revegetation programs.

English

Accurate prediction of gas planar distribution is crucial to selection and development of new CBM exploration areas. Based on seismic attributes, well logging and testing data we found that seismic absorption attenuation, after eliminating the effects of burial depth, shows an evident correlation with CBM gas content; (positive) structure curvature has a negative correlation with gas content; and density has a negative correlation with gas content. It is feasible to use the hydrocarbon index (P*G) and pseudo-Poisson ratio attributes for detection of gas enrichment zones. Based on seismic multiple-attribute analyses, a multiple linear regression equation was established between the seismic attributes and gas content at the drilling wells. Application of this equation to the seismic attributes at locations other than the drilling wells yielded a quantitative prediction of planar gas distribution. Prediction calculations were performed for two different models, one using pre-stack inversion and the other one disregarding pre-stack inversion. A comparison of the results indicates that both models predicted a similar trend for gas content distribution, except that the model using pre-stack inversion yielded a prediction result with considerably higher precision than the other model.

Survey on a Novel Wireless Sensor Network Communication at 433MHz Frequency

Wireless underground sensor networks (WUSN) are a promising new technology for monitoring soil information with a high spatial and temporal resolution for large areas. However, the significantly high attenuation caused by soil is the main challenge for the feasibility of WUSN. Recent theoretical results highlight the potential of smaller attenuation rates with the use of smaller radio frequencies. In this paper, experimental measurements have been conducted with commodity sensor nodes at the frequency of 433 MHz. Experiments are run to examine the received signal strength of correctly received packets and the packet error rate for a communication link. The tests show the potential feasibility of the WUSN with the use of powerful RF transceivers at 433MHz frequency. Moreover, we also illustrate a classification for wireless underground sensor network communication. Finally, we conclude that the effects of burial depth, inter-node distance and volumetric water content of the soil on the signal strength and packet error rate.

Effects of soil reinforcement on uplift resistance of buried pipeline

Pipeline failure caused by low uplift resistance in soil is a serious environmental and economic issue. Hence, having access to higher uplift resistance of pipeline through soil reinforcement has received considerable attention. The objective of this study is to examine the effect of performing geogrid to increase the uplift resistance of buried pipelines. To examine the effect of burial depth, pipe diameter, length of geogrid layers and the number of geogrid layers on the peak uplift resistance (PUR) of loose sand, 33 small-scale tests were performed in the laboratory. Results of laboratory tests reveal that depth of burial and pipe diameter have a direct effect on the PUR results. The findings show that the number of geogrid layers does not have a remarkable influence on PUR values. While the residual PUR values are of interest, for the same length of geogrid, the use of two layers of geogrid instead of one is advantageous. To verify the experimental results, 33 experiments were back analyzed using “PLAXIS 3D TUNNEL” program. It was found that experimental and numerical results are in good agreement.

Numerical Finite-Element Investigation of the Parameters Influencing the Behavior of Flexible Pipes for Culverts and Storm Sewers under Truck Load

AbstractThe objectives of this study are to evaluate the parameters that affect the behavior of flexible pipes for culverts and storm sewers and to examine the strength-limit states of such pipes proposed by the AASHTO bridge-design specifications. The flexible pipes investigated in the study are high-density polyethylene (HDPE), PVC, and metal pipes. The pipe diameters considered are 914 mm (36 in.) and 1,219 mm (48 in.). A three-dimensional finite-element (FE) model has been developed to simulate the behavior of buried pipes under truck load. Results from field tests conducted by the authors for large-diameter pipes under 2D, 1D, and 0.5D burial depths, where D is the pipe diameter, were used to evaluate the accuracy of the numerical model. Extensive parametric studies were then carried out to examine the effect of burial depth, backfill soil quality, and compaction level on the buried pipes, and their results are reported in this paper. The effect of these parameters has been evaluated in terms of thru...

Effect of Buried Depth on Steady-State Heat-Transfer Characteristics for Pipeline-Flow Assurance

Summary Pipeline embedment into the seabed is a key consideration for offshore oil and gas developments with high-temperature fluids. To date, the mechanism of steady-state heat transfer from partially and fully buried pipes has been modeled predominantly through analytical and numerical approaches. The current study focuses on making detailed measurements of heat-transfer characteristics. A laboratory-scale experimental apparatus imitating a subsea pipeline partially or fully buried into the seabed is created. Hot flow of hydrocarbons inside oil and gas offshore pipelines and the cold external flow of seawaters are simulated by means of 70°C and 5°C water flows from two separate water tanks, respectively. The experiments are carried out for seven different burial depths representing a range of various burial configurations, from fully exposed to fully buried pipes. The temperatures measured on the external surface of the pipe are analyzed, and the overall heat-transfer coefficient of the pipe is calculated. The effect of burial depth on the overall heat-transfer coefficient is compared with analytical formulae.

Regeneration capacity of small clonal fragments of the invasive Mikania micrantha H.B.K.: effects of burial depth and stolon internode length.

The perennial stoloniferous herbaceous vine Mikania micrantha H.B.K. is among the most noxious exotic invaders in China and the world. Disturbance can fragment stolons of M. micrantha and disperse these fragments over long distances or bury them in soils at different depths. To test their regeneration capacity, single-node stolon fragments with stolon internode lengths of 0, 3, 6 and 12 cm were buried in soil at 0, 2, 5 and 8 cm depths, respectively. The fragments were growing for nine weeks, and their emergence status, growth and morphological traits were measured. The results indicated that increasing burial depth significantly decreased survival rate and increased the emergence time of the M. micrantha plants. At an 8-cm burial depth, very few fragments (2.19%) emerged and survived. Burial did not affect the total biomass and root to shoot ratio of the surviving M. micrantha plants that emerged from the 0- and 2-cm burial depths. Increasing internode length significantly increased survival rate and growth measures, but there was no interaction effect with burial depth for any traits measured. These results suggest that M. micrantha can regenerate from buried stolon fragments, and thus, disturbance may contribute to the spread of this exotic invader. Any human activities producing stolon fragments or facilitating dispersal should be avoided.

Development of a new wireless sensor network communication

Wireless underground sensor networks (WUSN) are a natural extension of the wireless sensor networks (WSN) phenomenon to the underground environment. In this work, experimental measurements are presented at the frequency of 433 MHz, which show a good agreement with the theoretical studies. Experiments are run to examine the received signal strength and the packet error rate for aboveground-to-underground and underground-to-aboveground communication links. The results reveal that the effects of burial depth, inter-node distance and volumetric water content of the soil on the signal strength and packet error rate. The tests show that the communication range decreased when the soil moisture increased.

Effects of burial depth on seed germination and seedling emergence of Mexican oaks: A glasshouse experiment

Despite the interest in restoring oak forests in Mexico, very little is known about their regeneration ecology. We assessed the influence of acorn burial depth on seed germination and seedling emergence for eight Mexican oak species (Q. affinis, Q. castanea, Q. coccolobifolia, Q. laeta, Q. mexicana, Q. polymorpha, Q. tinkhamii and Q. viminea). We performed a glasshouse experiment in which acorns were buried at five soil depths (0, 2, 4, 6 and 8 cm). After four months, acorn germination and seedling emergence were recorded. Buried acorns showed higher germination and seedling emergence than unburied ones, but burial depth also influenced these responses. The optimum burial depth for seedling emergence of each species was 2, 4, 6 and 8 cm depth for four species (Q. castanea, Q. mexicana, Q. tinkhamii, and Q. viminea); 2 and 4 cm for Q. laeta; as well as 2, 4 and 8 cm for Q. coccolobifolia.

Survival of buried Sclerotinia sclerotiorum sclerotia in undisturbed soil

Sclerotia of S. sclerotiorum are surviving structures and the most important source of inoculum in sunflower fields. There are few studies about sclerotia survival in uncultivated soil and in accordance to that our objective was to establish the effect of burial depth on sclerotia longevity and the ability of carpogenic germination. In the trial (2009-2011) sclerotia were buried at the depth of 5, 10 and 30 cm and recovered every year in June. In laboratory sclerotia survival and carpogenic germination were examined. Our results showed that a large percentage of sclerotia survive at least three years under suitable conditions of temperature and moisture. In the case of continuous flooding (2011) sclerotia placed shallow in the soil (5 cm) were completely destroyed. Achieved results suggest that in undesturbed soil sclerotia placed deeper in the soil (10 and 30 cm) stay alive longer than those in upper soil (5 cm). Regardless of the burial depth sclerotia were able to produce apothecia under laboratory conditions. Resident saprofitic soil fungi (Aspergillus sp., Fusarium sp., Mucor sp. and mycoparasitic Conyothirium sp.) have been isolated equally from alive and deceyed sclerotia, but still less from the viable one.

Seed Germination and Seedling Development of the Seagrass Enhalus acoroides (L.f.) Royle in vitro: Effects of Burial Depths and Desiccation Periods

This study provides information on the feasibility of using Enhalus acoroides seeds as source of seedling materials for seagrass restoration effort and to support wider conservation initiatives. Mature seeds of E. acoroides were collected from Tubajon, Laguindingan, Misamis Oriental and were subjected to different laboratory conditions, namely burial depths and desiccation periods, to determine germination rate, seedling growth, and development. Seeds placed just above (control) and half-buried in the sediment fully germinated on the first day, while germination of fully buried seeds was delayed, attaining 93.3% germination on the fourth day. Seeds planted at 5 mm burial depth started germinating on the fifth day with only 56.7% germination success, while seeds buried deeply (15mm) did not germinate. All seeds subjected to desiccation germinated, but higher seedling survival (93.3 - 100%) was observed when seeds were desiccated at shorter periods of up to two hours while the lowest seedling survival (64.8%) was observed after a 12h desiccation period. One-way ANOVA showed significant differences in seedling survival and shoot length (p 0.05). Results have demonstrated that seed germination and the subsequent seedling development were adversely affected by burial depths and desiccation periods. Seedlings at 5mm burial depth and 12h desiccation period exhibited black and white spots, curled and yellowish leaves, stunted growth, and high mortality rates.

Intense fragmentation and deep burial reduce emergence of Rumex crispus L.

Mechanical control through different tillage methods is a common measure against perennial weeds. However, non-optimal tillage can potentially increase the vegetative regeneration instead of reducing it. Aspects of regenerative capacity in the perennial weed species Rumex crispus L. was studied in three pot and box experiments as follows: (1) regeneration from different root fragments under varying test conditions; (2) effects of root size and burial depth on time of emergence and emergence rate; and (3) effects of burial depth and cutting on biomass production and seed production. In experiment 1, sprouting occurred mainly from the neck of the roots, consisting of underground stem tissue. A few shoots were observed also from the upper half of the true taproot and from a side root. No difference in sprouting was found between test conditions. In experiment 2, total emergence rate was positively related to root size and negatively related to burial depth. Time to first emergence was defined by an interaction between the two factors. Roots larger than 100 g gave rise to a high degree of emergence from all burial depths, while emergence from roots weighing 20–30 g was less than 30% from 12 cm and nonexistent from 18 cm. When emergence and shoot production were tested under different cutting regimes (experiment 3), the separated top fragments of the roots sprouted faster and produced more shoot biomass than intact rootstocks, even at a second harvest. Our results indicate that fragmentation can stimulate sprouting from the regenerative tissue of the taproot. Hence, if tillage is carried out as weed control it is important that root fragments are buried at ploughing depth, especially if the population consists of adult plants.

Effects of Burial Depth and Substrate on the Emergence of Bromus rubens and Brassica tournefortii

The germination of seed is critical in deserts where annual plants are abundant and rely on seed buried in the soil for sustaining populations. The exotic annuals Bromus rubens and Brassica tournefortii threaten arid indigenous ecosystems such as the Mojave Desert, but little is known about the potential effects on seed emergence of different burial depths and substrates that could enhance or reduce emergence. Using seed from Mojave Desert populations, we conducted a three-factor greenhouse experiment testing the effects of species (Bromus or Brassica), burial depth (0, 2, 5, or 10 cm), and substrate (none, gravel, or litter) on seed emergence. Species and substrate interacted significantly with burial depth. Both species displayed the greatest emergence when seeds were sown on the soil surface (70% emergence for Bromus and 52% for Brassica), but Bromus emergence declined less at a 2-cm depth than Brassica. Emergence of surface-sown seed did not differ significantly among substrate types, but emergence of buried seed was significantly reduced below gravel substrates compared to no substrate or litter substrates. This suggests that seed fates in the soil (such as seed mortality by germination but not emergence from the soil) can be altered by manipulating soil surface conditions.

Seed germination and seedling development of Prunus armeniaca under different burial depths in soil

A semi-greenhouse study was conducted to understand the effects of soil burial depth on seed germination and seedling development. The seeds of wild apricot (Prunus armeniaca) were buried at the soil depths of 0-cm, 4-cm, 8-cm, and 12-cm, respectively, to simulate the seed hoarding behavior of rodents in the field. The results revealed that the rates of seed germination and established seedlings from buried seeds were both the highest in 4-cm burial depth group, and then decreased with increasing soil depth. The number of rotten seeds increased in deeper burial depth. It is unfavourable for seed germination at 0-cm burial depth (i.e., seeds were laid on soil surface). There was insignificant effect of burial depth on growth of established seedlings. The results from this study indicated that proper burial depth in soil would be helpful for the seed germination and seedling growth. The seedlings derived from buried seeds at shallower depth (4 cm) in this research have advantage in their early development.

Three-dimensional ground displacements from static pipe bursting in stiff clay

Three-dimensional ground surface displacements from 20 m long static pipe-bursting experiments are reported. These experiments were conducted with firm-to-stiff clay backfill in a trench with very stiff clay sidewalls at three different burial depths. Multiple digital cameras and image analysis were used to quantify the surface response as the expander progressed through the original pipe. The experiments quantified the upward surface movement as the expander approached, the effect of burial depth on maximum uplift, and the final amount of uplift after it decreased to a residual displacement. The experiments also quantified the axially forward ground surface movement as the expander approached, reaching maximum just ahead of the expander, and decreasing to almost zero after the expander had passed by. Lateral movements of the ground surface away from the centreline are also reported, which were essentially zero at the centre line, increasing to a maximum and then decreasing with distance from the centreline. The three different burial depths produced in effect the same width of vertical surface response with the displacements contained within 1.5 m on either side of the centreline, suggesting that the very stiff clay trench walls had a dominant influence on the measured displacements.

Effects of burial depth and water depth on sprouting of turions and early growth of Myriophyllum oguraense Miki subsp. yangtzense Wang

Sedimentation and water depth are important determinants of early growth and survivorship for aquatic macrophytes. Myriophyllum oguraense subsp. yangtzense Wang is a submerged macrophyte endemic to China and grows readily in shallow lakes of the lower Yangtze River basin. To clarify the ecology, turion emergence and biomass allocation were investigated by buring turions at 0, 2, 4, and 6 cm depths in plastic pots with unsterilized lake sediment under 0, 15, and 60 cm water depths. Emergence percentage was greatly affected by burial depth and water depth. Turion sprouting rate was highest at 0 cm burial depth, and decreased with increasing burial depth at each water depth. Total biomass, plant height, above-ground stem mass ratio and root mass ratio were significantly affected by both burial depth and water depth. With increasing water depth, total biomass, plant height, root mass ratio, above-ground stem mass ratio and leaf mass ratio decreased, while below-ground stem mass ratio generally increased with increasing burial depth. Our data suggest that both burial depth and water depth are important determinants for the sprouting of turions and early growth process of M. oguraense subsp. yangtzense. We therefore conclude that sediment accumulation and water-level fluctuation might disrupt the natural regeneration for turions of M. oguraense subsp. yangtzense, which in turn influences its abundance, distribution and population dynamics.

Aerial seed bank in Artemisia species: how it responds to sand mobility

Aerial seed bank has been found in the arid dune ecosystem. However, the relationship of aerial seed bank to sand mobility intensity is unknown. The adaptation of aerial seed bank to sand mobility was analyzed in four Artemisia species dominating at different habitats in northeastern Inner Mongolia, China. The four species, Artemisia gmelinii,A. frigida,A. halodendron and A. wudanica, are an interdune lowland, stabilized dune, semi-stabilized dune and active dune species, respectively. Seed (achene and capitulum) persistence on the parent plants, the supplement for the soil seed bank, the maintenance of seed viability, and the effect of burial depth on seedling emergence of these four species were studied. Dispersal delay differed interspecifically responding to sand mobility intensity: maximal dispersal was in the following May after maturation for A. wudanica, in the following April after maturation for A. halodendron, and in November of the year of seed maturation for A. frigida and A. gmelinii. The maximal supplement to the soil seed bank for A. wudanica and A. halodendron occurred in the following May and March, respectively. The viability of achenes in aerial seed bank of A. wudanica and A. halodendron maintained at 79.5 and 79.6% until the following May after maturation. This study indicated that aerial seed bank in the sand dune ecosystem functions to postpone seed dispersal until the end of windy season and the start of growing season, and therefore is a mechanism for psammophyte to adapt to sand mobility.

Effect of burial depth and soil water regime on the fate of Lithospermum arvense seeds in relation to burial time

Summary Lithospermum arvense is an increasing annual weed in winter crops of the semiarid region of southern Argentina under low impact tillage systems, an agricultural practice that has become popular in recent years. Seed distribution in the soil profile under conventional tillage will change when reduced tillage is implemented, thus affecting the germination microenvironment. The effect of seed burial depth and soil water regime on field germination, enforced dormancy, innate dormancy and seed decay was studied in relation to burial time in a field experiment. In addition, the effect of burial depth on seed germination and seedling emergence was examined under laboratory controlled conditions. Field germination of buried seed ranged from 55% to 65% for shallow (2 cm) and from 5% to 30% for greater depths (20 cm). Enforced dormancy levels were significantly higher among deeper seeds. The amount of innate dormant seeds was reduced to <10% after a year of burial. Lithospermum arvense seedbanks can be classified as short‐term persistent. Germination in the laboratory was unaffected by burial depth, while seedling emergence reduction was adequately described by a sigmoidal model. Results indicate that agricultural practices that accumulate L. arvense seeds near the soil surface enhance seedling recruitment.

The Effect of Burial Depth on Removal of Seeds of Phytolacca americana

Although burial is known to have important effects on seed predation in a variety of habitats, the role of burial depth in affecting the removal of seeds in early- successional systems is poorly known. Phytolacca Americana (pokeweed) is a model species to examine the role of burial depth in affecting seed removal because it is common in early-successional habitats, studies suggest that seed removal is indicative of seed predation, and seed predation is related to the recruitment of mature plants. To determine how burial depth affects P. americana seed removal, 20 seeds of P. americana were buried at depths of 0, 1, or 3 cm in early-successional habitats at the Savannah River Site in South Carolina for over 6 weeks. The frequency with which seeds were encountered (as measured by the removal of at least one seed) and the proportion of seeds removed was significantly greater when seeds were on the soil surface (0 cm depth) compared to seeds that were buried 1 cm or 3 cm; there was no difference in encounter or removal between seeds at 1 cm or 3 cm. Our findings suggest that burial may have important consequences for P. americana population dynamics, because seed survival depends upon whether or not the seed is buried, and relatively shallow burial can yield large increases in seed survival. Because seed limitation is known to be an important determinant of plant community composition in early- successional systems, our work suggests that burial may play an unappreciated role in the dynamics of these communities by reducing predator-mediated seed limitation.

Influence of mechanical rhizome cutting, rhizome drying and burial at different developmental stages on the regrowth of Calystegia sepium

SummaryThe regrowth of Calystegia sepium was studied in three types of experiments during spring 2003 and spring 2004. In one glasshouse experiment, rhizome fragments were planted in pots and either harvested at six different developmental stages to assess their undisturbed development and growth or harvested at 420 day degrees after burial to measure their regenerative capacity. Regrowth gradually declined as the plants had more expanded leaves at the time of burial. Minimum regenerative capacity was found when plants had four to eight fully expanded leaves and this coincided with the growth stage of minimum dry weight of underground regenerative organs. The effects of burial depth and rhizome fragment length were studied in outdoor container experiments. Burial at 15 or 25 cm reduced above‐ and below‐ground biomass in 2004, while 25 cm deep burial was necessary to reduce regrowth in 2003. Fragmentation had generally little effect on production of above‐ and below‐ground biomass, whereas burial and fragmentation delayed emergence time. Sensitivity of rhizomes to drying was studied in a growth chamber. Drying periods of 12 or 24 h did not have an influence on the production of aerial shoots, whereas 48 or 96 h reduced production of above‐ground biomass significantly. The experiments indicated that the minimum regenerative capacity would be at about 5–6 leaf stage and that mechanical disturbance at this stage would optimise weed control.