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Wet Soils (wet + soil)
Selected AbstractsNew records of chytridiaceous fungi (Chytridiomycota) from the Reserva Natural Selva Marginal Punta Lara (Argentina) with comments on some previously reported speciesNORDIC JOURNAL OF BOTANY, Issue 3-4 2008Agostina V. Marano The Chytridiomycota (chytrids) of Argentina are not well known from freshwater and terrestrial ecosystems. We collected samples of water and floating organic matter (vegetable debris) from a lotic environment and wet soil from four terrestrial habitats at the Reserva Natural Selva Marginal Punta Lara (Bs. As.) and added cellulosic, chitinic and keratinic baits to these samples. We also placed Rosa spp. fruits and corn leaves for colonization in the stream. We recorded 21 taxa. Four of them (Chytriomyces hyalinus var. granulatus, Cylindrochytridium johnstonii, Cladochytriumreplicatum and Septochytrium variabile) are new records for Argentina and we describe and illustrate them here. [source] Rice straw management: the big wasteBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2010Laura Domínguez-Escribá Abstract Rice is one of the major foods, with consumption per capita of 65 kg per year, accounting for 20% of global ingested calories. Rice production is expected to increase significantly in the near future in order to feed the rising human population. Today, paddy rice culture produces 660 million tons of rice, along with 800 million dry tons of agricultural residues, mainly straw. This biomass is managed predominantly through rice straw burning (RSB) and soil incorporation strategies. RSB leads to significant air pollution and has been banned in some regions, whereas stubble and straw incorporation into wet soil during land preparation is associated with enhanced methane emissions. Therefore, both strategies have important deleterious environmental effects and fail to take advantage of the huge energy potential of rice straw. Using rice straw as lignocellulosic biomass to produce bioethanol would appear to be a promising and ambitious goal to both manage this agricultural waste and to produce environmentally friendly biofuel. Technical difficulties, however, associated with the conversion of lignocellulose into simple, fermentable sugars, have hampered the massive development of rice-straw-derived bioethanol. Recent technical advances in straw pre-treatment, hydrolysis and fermentation may, however, overcome these limitations and facilitate a dramatic turnover in biofuels production in the near future. Copyright © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Nutrient requirements of ephemeral plant species from wet, mesotrophic soilsJOURNAL OF VEGETATION SCIENCE, Issue 3 2001Emiel; Brouwer van der Meijden (1996) Abstract. Nanocyperion plant communities occur on wet, more or less nutrient-poor and sparsely vegetated soils in temperate climates and are characterized by tiny, very shortlived plant species. Most of these have become locally extinct. It is generally assumed that drainage and eutrophication were the most important reasons for this decrease. However, chemical analysis of soil pore water from plots on growth sites of these ephemerals showed that phosphorus availability was relatively high. In a greenhouse experiment, the growth of ephemeral species was strongly limited by the amount of available phosphorus, whereas there was little or no limitation to the growth of other plant species from this habitat. At low phosphorus concentrations, the ephemeral species reached their reproductive phase within the same period, but showed a strong reduction in the amount of flowers that were produced. We concluded that ephemeral species in particular require a minimum amount of phosphorus for reproduction. Other species on nutrient-poor, wet soils have a longer life span and can postpone flowering in nutrient-poor soils. In contrast to other short-lived plant species from the same habitat, the growth of ephemeral species was barely stimulated by enhanced nitrogen availability. Apparently, the ephemerals are adapted to low nitrogen concentrations. The occurrence on nitrogen-poor and relatively phosphorus-rich soils suggests that this community may be very sensitive to nitrogen deposition. Reduced phosphorus availability below the minimum requirements of ephemerals, for example after acidification or the exclusion of human activities, has possibly contributed to the decrease of ephemeral plant species. [source] Thermal characterisation of active layer across a soil moisture gradient in the McMurdo Dry Valleys, AntarcticaPERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2009Scott J. Ikard Abstract Heat transport into active layer soils is important to understanding potential responses to changes in surface energy balance, particularly in the context of changing climate. Here we present results of a study to characterise soil thermal properties along a soil moisture gradient adjacent to Lake Fryxell in Taylor Valley, Antarctica. Our goals were to characterise the thermal characteristics of these relatively wet soils (compared to the rest of the McMurdo Dry Valleys landscape), and to assess the response of the active layer to possible increases in soil moisture. We measured subsurface temperatures at depths from 3 to 50,cm at four locations along a natural gradient of wet to dry soils adjacent to Lake Fryxell from January 2006 to January 2007. We used a numerical model to estimate apparent thermal diffusivity (ATD) and simulate observed temperature time series. Calculations of ATD at discrete locations yielded values ranging from 1.0,×,10,9 , 2.4,×,10,5,m2,s,1, and the corresponding range of bulk (i.e. depth averaged at a single surface location) ATD was 2.9,×,10,9,1.2,×,10,7,m2,s,1. Thawed soils had a range of bulk ATD during warming of 2.9,×,10,9,3.8,×,10,8,m2,s,1, and during cooling of 2.9,×,10,9,4.8,×,10,8,m2,s,1. When soils were frozen, however, the range of bulk ATD was 7.6,×,10,9,1.2,×,10,7,m2,s,1 during warming, and 7.8,×,10,9,1.1,×,10,7,m2,s,1 during cooling. Estimated bulk ATD values were consistently greater in locations of enhanced soil moisture, so lakeside soils were more likely to conduct energy into the subsurface. Increased soil moisture across the landscape would likely increase ATD, allowing for greater heat exchange between the atmosphere and the subsurface. Copyright © 2009 John Wiley & Sons, Ltd. [source] Impact of soil moisture on the development of a Sahelian mesoscale convective system: a case-study from the AMMA Special Observing PeriodTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue S1 2010Christopher M. Taylor Abstract Interactions between the land and atmosphere play an important role in the precipitation of the Sahel. The African Monsoon Multidisciplinary Analysis Special Observing Period provided observations with which to illuminate potential feedback mechanisms. This case-study highlights a major storm which developed over northern Mali in an area where a research aircraft was surveying the atmospheric response to soil moisture features. Soil moisture variability is characterized using satellite land-surface temperature data whilst cloud images illustrate the evolution of the storm and its relationship to the surface. Measurements in the planetary boundary layer (PBL) indicate mesoscale variations in pre-storm humidity and temperature consistent with high evaporation from wet soils. The storm developed above a dry surface within a wetter region with cells first appearing along a wet,dry soil boundary. This suggests that the storm was triggered in association with low-level convergence driven by the soil moisture pattern. A gravity wave propagating away from a remote mature storm also appears to have played an important role in the initiation, though only in the region of the soil moisture contrast did deep convection become established. Once organised into a Mesoscale Convective System, convection developed over wet areas as well as dry, and indeed at this stage, convection became more intense over wetter soils. This behaviour is consistent with the large gradients in PBL humidity. The study illustrates the complexity of soil moisture,convection feedback loops and highlights the mechanisms which may operate at different stages of a storm's life cycle. Copyright © 2009 Royal Meteorological Society [source] | ||||||||||