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Journal ArticleDOI

Factors Influencing Shoot Production and Mineral Nutrient Levels in Typha Latifolia

01 Mar 1970-Ecology (John Wiley & Sons, Ltd)-Vol. 51, Iss: 2, pp 296-300
About: This article is published in Ecology.The article was published on 1970-03-01 and is currently open access. It has received 131 citations till now. The article focuses on the topics: Typha & Shoot.

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Citations
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Journal ArticleDOI
TL;DR: In this paper, a review summarizes the mechanisms of freshwater wetland interaction with sediment and nutrients that affect surface water quality, including sedimentation, plant uptake, litter decomposition, retention in the soil and microbial processes.
Abstract: Freshwater wetlands alter surface water quality in ways which benefit downstream use. This review summarizes the mechanisms of freshwater wetland interaction with sediment and nutrients that affect surface water quality. The mechanisms vary in magnitude and reversibility, and differ among wetland types. They include sedimentation, plant uptake, litter decomposition, retention in the soil, and microbial processes. Sedimentation is a relatively permanent retention mechanism whereby particulates and associated contaminants are physically deposited on the wetland soil surface. Plant uptake and litter decomposition provide short‐to long‐term retention of nutrients, depending on rates of leaching, translocation to and from storage structures, and the longevity of plant tissues. Plant litter can also provide a substrate for microbial processing of nutrients. Wetland soils sorb nutrients, and provide the environment for aerobic and anaerobic microorganisms that process nutrients. Wetland storage compartm...

507 citations

Journal ArticleDOI
TL;DR: Recent studies show that artificially created wetlands can be effective systems for nutrient removal only if their internal removed mechanisms are understood and if these are optimized by management techniques.
Abstract: SUMMARY. 1 This review considers the internal fluxes and transformations of nitrogen and phosphorus in wetland ecosystems. Emphasis is placed on the dynamic nature of nutrient cycling and the review is slanted towards an applied perspective, namely the possible use of wetlands as sinks for unwanted nutrients. 2 A number of basic concepts pertaining to wetland ecosystems are first explained. These are: successional time scales, exchange equilibria and the concepts of storage and through flow, resource consumption and supply including the ideas of new and regenerated nutrients and the nutrient spiralling concept. Much of the following review material is referenced back to these concepts. 3 Descriptions of the basic pathways of nutrients through different types of wetland systems are given with the emphasis placed on the movement into and out of the major storage compartments of wetland systems. 4 The problems of conversion of qualitative information (or data in concentration units) on nutrient movements and transformations, into data on mass flows are then discussed. The importance of understanding groundwater, evapotranspiration processes and the effects of floods and seasonality on mass flow calculations can be significant. Unidentified groundwater sources can dilute nutrient concentrations, and evapotranspiration can increase concentrations. The pattern of through flow can also alter nutrient levels. Increasing residence time has the effect of decreasing nutrients in the wetland outflow. 5 The review then considers the effects of adding nutrients to wetlands. The concept of the loading capacity is discussed in relation to the length of time a wetland can continue to remove nutrients from through flow. Sediment accumulation and degassing are seen as the major long-term nutrient sinks. Nutrient enrichment results in biological changes to wetlands. These involve both changes in species composition and productivity. Not all are deleterious. 6 The literature indicates that natural wetlands are not particularly effective as nutrient sinks when compared with conventional stripping plants but their value lies in removal of diffuse nutrient runoff at low concentrations. Dealing with this type of runoff by conventional means is not generally feasible. 7 Recent studies show that artificially created wetlands can he effective systems for nutrient (particularly N) removal only if their internal removed mechanisms are understood and if these are optimized by management techniques.

310 citations

Journal ArticleDOI
TL;DR: In this article, it is shown that the fraction of nitrogen in wetlands that could be lost by hydrologic export is probably a small fraction of the potentially mineralizable nitrogen and is certainly a negligible fraction of total nitrogen in the system.
Abstract: The biogeochemistry of N in freshwater wetlands is complicated by vegetation characteristics that range from annual herbs to perennial woodlands; by hydrologic characteristics that range from closed, precipitation-driven to tidal, riverine wetlands; and by the diversity of the nitrogen cycle itself. It is clear that sediments are the single largest pool of nitrogen in wetland ecosystems (100's to 1000's g N m-2) followed in rough order-of-magnitude decreases by plants and available inorganic nitrogen. Precipitation inputs (< 1–2 g N m-2 yr-1) are well known but other atmospheric inputs, e.g. dry deposition, are essentially unknown and could be as large or larger than wet deposition. Nitrogen fixation (acetylene reduction) is an important supplementary input in some wetlands (< < 1–3 g N m-2 yr-1) but is probably limited by the excess of fixed nitrogen usually present in wetland sediments. Plant uptake normally ranges from a few g N m-2 yr-1 to ∼ 35 g N m-2 yr-1 with extreme values of up to ∼ 100g N m-2 yr-1 Results of translocation experiments done to date may be misleading and may call for a reassessment of the magnitude of both plant uptake and leaching rates. Interactions between plant litter and decomposer microorganisms tend, over the short-term, to conserve nitrogen within the system in immobile forms. Later, decomposers release this nitrogen in forms and at rates that plants can efficiently reassimilate. The NO3 formed by nitrification (< 0.1 to 10 g N m-2 yr-1 has several fates which may tend to either conserve nitrogen (uptake and dissimilatory reduction to ammonium) or lead to its loss (denitrification). Both nitrification and denitrification operate at rates far below their potential and under proper conditions (e.g. draining or fluctuating water levels) may accelerate. However, virtually all estimates of denitrification rates in freshwater wetlands are based on measurements of potential denitrification, not actual denitrification and, as a consequence, the importance of denitrification in these ecosystems may have been greatly over estimated. In general, larger amounts of nitrogen cycle within freshwater wetlands than flow in or out. Except for closed, ombrotrophic systems this might seem an unusual characteristic for ecosystems that are dominated by the flux of water, however, two factors limit the opportunity for N loss. At any given time the fraction of nitrogen in wetlands that could be lost by hydrologic export is probably a small fraction of the potentially mineralizable nitrogen and is certainly a negligible fraction of the total nitrogen in the system. Second, in some cases freshwater wetlands may be hydrologically isolated so that the bulk of upland water flow may pass under (in the case of floating mats) or by (in the case of riparian systems) the biotically active components of the wetland. This may explain the rather limited range of N loading rates real wetlands can accept in comparison to, for example, percolation columns or engineered marshes.

272 citations

Journal ArticleDOI
TL;DR: Aquatic plants have potential as feedstuffs in certain nations, but the economics of harvesting and processing would prohibit their direct utilization as a forage in technologically advanced nations as mentioned in this paper.
Abstract: Aquatic plants have potential as feedstuffs in certain nations, but the economics of harvesting and processing would prohibit their direct utilization as a forage in technologically advanced nations. However, nutrient pollution is accelerating rates of eutrophication of natural waters in many areas. Aquatic plants produce large standing crops and accumulate large amounts of nutrients. Systems based on the harvest of aquatic plants have potential application in removing nutrients from effluents and natural waters.

204 citations

References
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01 Jan 2014
TL;DR: Soil chemical analysis, Soil Chemical Analysis (SCA), this paper, is a technique for soil chemical analysis that is used in the field of Soil Chemistry and Chemical Engineering.
Abstract: Soil chemical analysis , Soil chemical analysis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

13,439 citations

Journal ArticleDOI
TL;DR: The principles of comparative productivity and the net primary productivity of different types of plant community are discussed, which help clarify the role of waste and energy in the productivity of a plant community.
Abstract: Summary 1. This article discusses the principles of comparative productivity and the net primary productivity of different types of plant community. 2. Primary production is denned as the weight of new organic matter created by photosynthesis over a period; expressed as a rate it becomes productivity. Biomass is defined as the total weight of plant present at a particular time. Crop, yield and standing crop are comparable with production, productivity and biomass respectively, but refer to the parts of the plant normally harvested or sampled. 3. Net production is that part of the gross photosynthetic production which is not respired by the plant, and hence becomes available for utilization. 4. Ways of adjusting source data to a common form are examined at length, for meaningful comparisons are impossible if this is not done. Source data are published according to a great variety of criteria such as fresh weight, dry weight, oxygen production and carbon fixation. Standing crop or yield data need correction for omitted parts of the plant. The determination of productivity from changes in biomass may involve corrections for material accumulated from earlier periods and for losses due to death or grazing. Conversions from gross production to net production are usually required when photosynthetic determinations are made. 5. Problems raised by the use of different units are discussed and selected factors for conversions to the recommended units are listed. 6. The basis adopted for comparisons is the maximum average annual net productivity of organic (ash-free) matter that can be attained over a large area. This facilitates the comparison of the productivity of different types of community by minimizing differences due to local site conditions and weather, and is the most useful measure for general ecological purposes. For some selected examples the productivity and biomass are expressed in a variety of other ways to facilitate direct comparisons with source data. 7. Methods for determining productivity are only discussed in so far as the details affect the comparability of the results. 8. The most productive temperate communities appear to be fertile reedswamps which may produce 30–45 metric tons per hectare in a year. Coniferous forests, and perennial plants under intensive cultivation, may produce 25–40 m.t./ha. Deciduous forests, uncultivated herbs and cultivated annual plants are less productive (10–25 m.t./ha.). 9. The most productive communities of all appear to be found in the tropics. Rain forests and perennial plants under intensive cultivation may produce 50–80 m.t./ha. in a year and it is probable that swamps are similar. Cultivated annual plants only attain 25–35 m.t./ha. 10. The phytoplankton of lakes and oceans are relatively poorly productive even on fertile sites, with an annual production of only 1–9 m.t./ha. Values greater than 3 m.t./ha. are only achieved in waters enriched by man's activities, or in the tropics. Submerged freshwater macrophytes are no more productive in the temperate region but may attain 13–21 m.t./ha. in warmer climates. Benthic marine plants in shallow waters may produce more; from 25–33 m.t./ha. in the temperate zone, rising to nearly 40 m.t./ha. by tropical coral reefs. Algae cultivated in sewage can produce up to 45 m.t./ha. and algae cultivated in mineral media, with carbon dioxide supplied artificially, may produce even more. 11. If it were possible to devise cultivation techniques which would enable plants to grow all the year at the rate normally attained for only short periods in their seasonal cycle, much greater annual productivities, up to 150 m.t./ha. year, might be attained. Eichhornia crassipes might be a suitable plant for such cultivation. 12. Assuming that the soil structure is good and that ample nutrients are available there appear to be three main ways of increasing yields; irrigating, using plants which maintain an active cover throughout the year, and developing techniques to obtain valuable products from plants, or parts of plants, not directly useable.

498 citations

Journal ArticleDOI
TL;DR: Results indicated that in all but one of the lakes, phosphorus supply was more likely to limit higher aquatic plant growth than was nitrogen, and a system was developed for culturing algae-free plants in a synthetic nutrient medium.
Abstract: A tissue analysis technique was used to evaluate nitrogen and phosphorus supplies in natural waters for the growth of angiosperm aquatic plants. Tissue content of nitrogen and phosphorus was employed as an index of element availability in lakes from which plants were collected. This required establishment in the laboratory of the critical level for each element, that is, the minimum tissue content associated with maximum growth. To establish critical levels, a system was developed for culturing algae-free plants in a synthetic nutrient medium. The critical nitrogen content for the several species studied was approximately 1.3%; the comparable phosphorus value was 0.13%. The nitrogen and phosphorus contents of 13 species of aquatic plants collected during the summer from nine lakes were compared with the critical concentrations. In nine samples obtained mostly during periods of heaviest plant growth, the phosphorus content was at or below the critical level; in no sample was the nitrogen content less than the critical concentration. The results indicated that in all but one of the lakes, phosphorus supply was more likely to limit higher aquatic plant growth than was nitrogen. The primary importance of this study is as an initial step in the development of a satisfactory technique for evaluating nutrient supplies in natural waters.

415 citations