Peat Substratum Research Articles

The variation of carbon content and bulk density on different time period post fire and peat depth

Peatland plays the biggest carbon sink and the biggest carbon stock is in the soil. The main factors determining the number of carbon stock are bulk density and soil carbon content. Fire has caused the changes in the soil biophysical condition however limited study has been performed. The aim of this study is to obtain the number of carbon content and bulk density on post burning sites and various peat depth. The study was conducted on post burning peatland sites after 22 years, 16 years, 5 years and one site that has never been burnt. Two hundred and eighteen soil samples were collected up to the 5 m depth. Laboratorium analysis was carried out using Loss of Ignition method. The result showed that the average carbon content was 52.65% with the biggest carbon content was 53.98% from the site that has never been burnt. Nevertheless, the carbon content was not effected by the fire scenes. Peat depth had effect on the carbon content adjacent to the peat sub-stratum. Generally, the carbon content was lower following the distance to peat sub-stratum however the number of carbon content varied on the upper layer of peat sub-stratum. The carbon content value was different with the conversion factor of 46% or 50%, respectively. It was shown by the diversity analysis that the conversion value different with the value of carbon obtained in this research (Pvalue < 0.05). The peat bulk density was not effected by the period of fire. Generally, the bulk density was bigger following the distance to peat sub-stratum and it showed no pattern on the upper layer of the peat sub-stratum. The implication of this study emphasized that the conversion factor for peatland should be more than 50% to prevent underestimate carbon stock prediction.

Effect of the Rhizospheric Micro-organisms of Some Fabaceaes and Peat Substratum on the Growth of Carob Tree (Ceratonia siliqua L.)

Intensive exploitation of sand quarry sites inevitably results in near total destruction of plant cover and soil degradation. The damage done is so important that without human intervention, soil scarification and vegetable return to growth may take several decades. In order to conduct a site rehabilitation programme successfully reforestation through the plantation of a native species such as the carob tree (Ceratonia siliqua) should be the appropriate choice. Because of their facilitation effect, the spontaneous leguminous plants present in the site, specifically Lotus creticus, Retama monosperma and L. creticus associated with R.monosperma can be used as nurse plants. Our assumption is that they possess a rhizosphere rich in microorganisms, which may positively impact the growth of carob. To this end, a study is conducted in order to: a) estimate the diversity of arbuscular mycorrhiza fungi (AMF) living underneath the spontaneous leguminous plants of the site; b) determine their combined effect with other microsymbionts (i.e., total bacteria and actinobacteria) on the growth of the carob tree; c) draw a comparison with carob grown in bare soil and in sterile soil mixed with peat regarding its growth parameters and mineral nutrition. The trees were grown in plastic pots under greenhouse conditions and, after 12 months, the results have shown that, against all odds, the soils of R. monosperma and L. criticus associated with R. monosperma do not significantly influence the growth of the tree whereas the impact of the soil of L. creticus is outright negative. On the other hand, peat improves the root and aerial growth of the tree, which shows in leaves number, branch number and capacity of nutrition in nitrogen. Because a little richer in actinobacteria, bare soil increases the length of the aerial parts and improves the tree&amp;rsquo;s phosphorus uptake.

Boosting saffron (Crocus sativus L.) micro-propagation through in vitro corm production

Lack of availability of quality planting material is hampering the National program of extending saffron area in Morocco. Tissue culture has been found to be a valuable substitute to vegetative propagation due to high proliferation ratio. Corm storage at 35°C has proved to be beneficial not only in making corms more responsive to shooting but also helps in extending corm dormancy thus enabling to remove the bottle neck of available tissue culture protocols being season dependent. These states of dormancy also facilitate the corms disinfection (100%) after been soaked in pure alcohol, and then in 50% bleach solution. Culturing of saffron corms on MS media supplemented with 1.5 mg L-1 BAP + 0.5 mg L-1 NAA helps to produce 12 shoots/corm after 4 weeks. Further sub-culturing on MS + 6.5 mg L-1 BAP + 0.2 mg L-1 NAA promotes shoot multiplication, and thereafter 16 weeks on a MS medium with 3 mg L-1 BAP in combination with 80 g L-1 sucrose leads to microcorm development up to 2 g weight without any dormancy and can be used successfully for a second multiplication cycle. Direct transfer of in vitro corms on peat substratum has been found promising. The in vitro micro-propagation seems to be a very promising technology for saffron production and will help in the diffusion of any genetic progress generated by the current participatory breeding program of saffron in Morocco.

The Effect of Peat and Vermicompost Cavitation Products on the Soil Biological Activity

Abstract Commercial products with humic substances have often been recommended for plant growth stimulation and yield improvement. The aim of this study was to clarify the effects of two products, containing cavited peat and vermicompost respectively on the soil biological activity. Vegetation experiments with garden cress and cucumbers were arranged in pots with a peat substratum in the greenhouses of the Latvia University of Agriculture. The plants were treated with the preparations once a month. The first treatment was done at sowing. Dose of 20, 2, 0.2 mL per m2 during each treatment time were used. A control variant was without peat or vermicompost preparation. Field experiments with onions were carried out in the organic farming experimental field of the Latvia State Institute of Cereal Breeding. Plant growth and soil (substratum) biological activity (respiration and enzymatic activity) were tested. Plant growth and response to the different preparations depended on the plant species and its development stage. The effect of preparations decreases during plant development. The impact of peat or vermicompost preparation on soil biological activity depended not only on the concentration of preparation, but was influenced by the soil or growth media type. The decrease of onion yield in field conditions as a result of preparations was observed.

The role of arbuscular mycorrhizal fungi in alleviating salt stress in Medicago sativa L. var. icon

Medicago sativa L. is the most important forage crop in arid and semi-arid areas, where increased salinity is a major factor limiting plant growth and crop productivity. The role of arbuscular mycorrhizal (AM) fungus Glomus viscosum H.T. Nicolson strain A6 in protecting alfalfa plants from salt stress, induced by sodium chloride (NaCl), was studied in two ways. Firstly, the root systems of 3-month old M. sativa plants, both mycorrhizal (AM+) and non-mycorrhizal (non-AM) (M. sativa L. var. icon), were placed in solutions of increasing salt concentrations (0, 50, 100, 150, 200 mM NaCl) to study the wilting response. G. viscosum improved the tolerance to salinity stress and the benefit was expressed in terms of the time required to reach the T4 stage in the wilting experiment. Secondly, to evaluate the ability of the Glomus-alfalfa symbiosis to tolerate salt, a pot experiment was set up in a glasshouse in which 3-month old alfalfa plants (M. sativa var. icon) were grown in a peat substratum at three salinity levels (0, 100, 150 mM NaCl). The AM symbiosis stimulated plant height, leaf area, root density, fresh and dry plant weight under saline conditions. Furthermore, proline accumulation was higher in mycorrhizal M. sativa plants than in non-mycorrhizal plants under conditions of salt stress. These and other results indicated that the micropropagated selected clone of M. sativa var. icon, when in symbiosis with G. viscosum H.T. Nicolson strain A6, exhibited better growth and physiological activities under saline conditions than non-AM plants. The AM+ plants also had lower sodium and chloride concentrations in tissues than non-AM plants.

Predicting the pressure–sinkage characteristics of two forest sites in Ireland using in situ soil mechanical properties

The mechanical properties of two forest soils in Ireland were determined in order to model the pressure−sinkage characteristics of the forest floor. The stiffness values of the surface mat and the underlying weak peat substrata, and Young's modulus were determined from in situ load–sinkage experimental data obtained from the sites. The measured mean values of stiffness of surface mat (underlying peat soil) were found to vary between 368 and 1634 (1028 and 4320 kN/m 3 ). The measured mean value of Young's modulus of the forest floor was found to vary between 427 and 718 kN/m 2 . A non–linear model that predicted the pressure–sinkage characteristics of the forest floor, with less than 19% error, was developed. Application of the non-linear model for prediction of potential site damage by timber harvesting and extraction machinery traffic was exemplified. Such application of the model has an advantage in that it only requires Young's modulus of the soil and harvesting machine configuration to be known.

Sphagnum establishment on bare peat: The importance of climatic variability and Sphagnum species richness

AbstractQuestion: What is the relative ability of four species of Sphagnum (S. fuscum, S. rubellum, S. magellanicum and S. angustifolium) to establish on bare peat substratum in the field when re‐introduced as single or multi‐species re‐introductions and in relation to interannual variations in climate?Location: Continental southeastern Canada.Methods: Diaspores (fragments) of four Sphagnum species alone or in combination were re‐introduced onto residual peat surfaces and were monitored to follow the development of the moss carpet over four growing seasons. In order to compare results under a variety of climatic conditions, this whole experimental setting was repeated four times (trials), with a four‐year follow‐up for each trial.Conclusions: The establishment rate of the moss carpet varied among years, in response to climatic variations between growing seasons. The relative success of different moss species and combinations of species, however, did not vary within or between trials. Thus, the species and combinations of species resulting in the highest short‐term or long‐term establishment rates remained the same for all trials, independent of the climatic conditions at the time of re‐introduction. Our results showed no link between the number of species in the diaspore mixture and successful establishment of the moss carpet. Yet successful regeneration was clearly influenced by the identity of species chosen for re‐introduction. S. fuscum, alone or in combination, was the species found to lead to the most extensive development of the moss carpet under the current test conditions.

Vegetation-controlled modern anastomosing system of the upper Narew River (NE Poland) and its sediments

The anastomosing system of the upper Narew River consists of a network of interconnected channels. The channels are relatively deep (width/depth ratio 2–10), straight to sinuous, and they lack natural levees. They are characterised by a low water slope and very low stream power. The river is distinctly bedload-dominated and the transport of suspended clastic fines is minimal. Channel deposits consist almost exclusively of medium- to coarse-grained sand. Laterally extensive interchannel areas are flat and covered with peat-forming vegetation. These stable wetlands are flooded for many weeks during high water stages. Except for the channels, the valley fill consists of peat layer reaching 4 m in thickness. The rate of vertical aggradation of the peat deposit is estimated at 1–1.5 mm/year. The radiocarbon dating indicates that the peat layer is predominantly late Holocene in age. The impact of vegetation on the system is overwhelming. Vegetation produces an erosion-resistant peat layer, stabilizes channel banks and slows down the water flow. Vegetation also stimulates aggradation of bedload material on the channel bottom, and contributes to avulsion by blocking the channels. The channel network owes its origin to repeated though infrequent avulsion. Avulsion in the studied system is a small-scale, gradational and slow process. New channels evolve very slowly because of unfavourable hydrologic conditions and the presence of a resistant peat substratum. A new channel eventually intercepts only a part of the flow, while the old channel is still active, though to a limited extent. Although newly formed channels might subsequently be abandoned, long-lasting ones predominate within the system.

Koeleria macrantha (Ledeb.) Schultes (K. alpigena Domin, K. cristata (L.) Pers. pro parte, K. gracilis Pers., K. albescens auct. non DC.)

<i>Koeleria macrantha</i> (Ledeb.) Schultes (<i>K. alpigena</i> Domin, <i>K. cristata</i> (L.) Pers. pro parte, <i>K. gracilis</i> Pers., <i>K. albescens</i> auct. non DC.)

Bearing capacity of forest access roads built on peat soils

Significance of the thickness of peat substratum on the bearing capacity of forest access roads laid on peat soils in Ireland is evaluated. Bearing capacity of an experimental pavement was assessed on the basis of its surface deflection measured using a Benkelman beam. The mean deflections for winter, spring and summer seasons were 2.7, 5.1 and 5.4 mm, respectively, and the lower value for winter was attributed to the frozen pavement and lower soil moisture conditions. Pavement response in winter was a function of the interaction term of linear components of thickness of pavement layers and the peat substratum ( R 2=0.67), while in spring ( R 2=0.70) and summer ( R 2=0.72), it also included a moderating quadratic term of thickness of the peat substratum. Deflection generally increased with thickness of pavement and the peat substratum, and effect of pavement thickness was pronounced under peat layer greater than 1000 mm which was attributed to inherent weakness of the pavements over such areas. It is suggested that thickness of the peat substratum may be a basis for developing specifications for timber haulage vehicles, or routeing of such traffic for minimal environmental impact.

Influence of inoculation with arbuscular mycorrhizal fungi on the growth and mycorrhizal infection of transplanted onion

Effects of inoculation with arbuscular mycorrhizal (AM) fungi on the growth and mycorrhizal infection of onion were observed in five field experiments. Onion seedlings pre-inoculated in multiple trays with peat substratum were transplanted after 6 weeks to the field plots containing steamed, fumigated or non-sterilised soil. Positive growth responses were found after inoculation with most fungal endophytes tested. Inoculated AM fungi were generally more effective than indigenous fungi from non-sterilised soil. The plant growth response to inoculation was higher when indigenous fungi in the soil were eliminated by steam sterilisation or fumigation. In one experiment, inoculation was most effective in non-fertilised and non-irrigated treatments, but the mycorrhizal growth response of the plants inoculated by some fungi was significant even when plants were fertilised and irrigated.

Évolution récente d'une tourbière à palses (Québec subarctique) : analyse cartographique et dendrochronologique

During the past 100 years, palsa bogs located on the eastern coast of Hudson Bay have undergone major changes associated with global climatic warming of the northern hemisphere. The recent main developmental stages of palsas, collapse scars, and thermokarstic pools were reconstructed within a representative permafrost peatland located in the southern part of the forest–tundra, using detailed mapping and tree-ring analyses. Maps of the peatland in 1957, 1973, and 1983 indicate a 49% decrease of the total cover of palsas and collapse scars between 1957 and 1983 and a 44% increase of the thermokarstic pool surface. Degradation of the palsa bog was more pronounced between 1957 and 1973 than between 1973 and 1983. Tree-ring analysis of reaction wood on black spruce (Picea mariana (Mill.) BSP.) exposed to unstable peat substratum indicates that permafrost degradation, which began as early as 1880, increased markedly between 1930 and 1965. During the 19th century, the permafrost peatland was mainly composed of large peat plateaus, which subsequently disintegrated into residual palsas, collapse scars, and thermokarstic pools. In addition the increase in temperature during the 20th century, it seems that milder winters with heavier snowfalls promoted conditions conducive to permafrost degradation. The constantly increasing contrast in the microtopographic pattern of the peatland, resulting from the transformation of peat plateaus into smaller palsa units, created more snow cover on east and southeast palsa slopes, thus accelerating permafrost degradation. This autocatalytic process seems to have also played a role in some sections of the peatland with abundant thermokarstic pools, where major changes in drainage conditions have stimulated thermokarstic erosion.

Peat Accumulation and the Success of Marsh Plants

Accumulated belowground plant debris in salt marsh habitats forms a compact peat substratum that generally increases in density from the littoral edge of marshes landward. To examine the influence of peat accumulation on the success of marsh plants, unvegetated substratum varying in peat density was transplanted over a tidal gradient in a New England salt marsh, and colonization of the plots was followed for 3 yr. Manipulated plots were established in the tall— and short—form Spartina alterniflora zones and near the littoral border of the Spartina patens zone. Substratum type markedly influenced plant colonization of plots in each zone. In the tall— and short—form S. alterniflora zones, the vigor of S. alterniflora invading plots decreased which increasing peat density. In both these zones, S. alterniflora production in experimental plots lacking peat exceeded even that in unmanipulated control plots, suggesting that natural peat accumulation in these habitats reduces plant production. Experimental plots in the S. patens zone also were colonized as a function of peat density. All plots in the S. patens zone were heavily colonized by S. alterniflora, suggesting that S. alterniflora is normally excluded from this habitat by the presence of high marsh vegetation. S. alterniflora invasion of the S. patens zone plots, however, precluded assessing the influence of substratum type on the success of the grasses normally found in this habitat. A physical parameter inventory of the experimental plots indicated that plant growth in the plots was not correlated with many edaphic conditions believed to favor marsh plant growth. For example, plots lacking peat had lower redox and total nitrogen, higher salinities, and lower permeability to water than peat substratum, yet supported more vigorous plant growth than plots containing peat. The basis of peat inhibition of marsh plant growth, therefore, is unclear and needs further work. These data suggest that peat accumulation in marsh habitats may inhibit plant growth, lead to autogenic changes in plant performance, and contribute to within— and between—marsh variation in plant production.

The Influences of Comminution and Compression of Substratum Peat on Growth and Drought Tolerance of Lodgepole Pine Container Seedlings

Lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) seedlings were grown in three peat substrata: (1) tubes filled with horticultural grade peat; (2) tubes filled with comminuted peat; and (3) tubes filled with comminuted, compressed peat. Treatment (3) gave the greatest seedling dry weights after 14 weeks in a drought tolerance experiment. Surviving seedlings grown in compressed, comminuted peat showed the greatest increase in total dry weight. These results were attributed tô compression of the peat.

THE VEGETATION OF NORTHERN MANITOBA: VI. THE LOWER HAYES RIVER REGION

The vegetation of the Hudson Bay Lowlands of Canada is known only in the most superficial terms. This contribution provides descriptions of the chief cover types of a small portion of the Lowlands near the confluence of the Hayes and Nelson rivers. The area has a continental, subarctic climate. Postglacial marine inundation has deposited thick calcareous clays; the topography is flat.On the mineral substrata of alluvial and marine deposits the chief types of vegetation are salt marsh, shrub (dominated by Salix species), forests of Populus balsamifera, and forests of Picea glauca. They often form discrete zones in the order mentioned, and it is likely that this is a seral as well as spatial relationship. On the extensive peat substrata there are bog and fen types. In the former are distinguished two communities dominated by Picea mariana—one, termed lichen muskeg, with a ground layer of Cladonia and Ledum, and the other, moss muskeg, with Pleurozium and Ledum groenlandicum as ground layer dominants. Locally, areas of lichen muskeg have been destroyed by fire and are now occupied by willow communities. In wet inland areas, moss muskeg and lichen muskeg communities are associated with palsa and string-bog features. On shallower peats, usually nearer the shores and rivers, fens predominate, with Larix laricina and Betula glandulosa as the dominant phanerophytes.All these types have been distinguished on vertical aerial photographs, and their photographic characteristics are summarized. A detailed vegetation map illustrates their chorology.