Showing papers on "Ecosystem published in 1977"

Biogeochemistry of a Forested Ecosystem

Abstract: Biogeochemistry of a forested ecosystem , Biogeochemistry of a forested ecosystem , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Wet Coastal Ecosystems

Abstract: Wet coastal ecosystems , Wet coastal ecosystems , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Nitrogen budget for an aggrading northern hardwood forest ecosystem.

Abstract: Long-term analyses of the structure and function of a northern hardwood ecosystem have resulted in measurement of the salient features of the nitrogen cycle. These data allow an evaluation of the importance of the various components and provide a framework for more efficient forest management.

Organic matter processing by a stream‐segment ecosystem: Fort River, Massachusetts, U.S.A.

Abstract: An annual organic matter budget for a 1700 m segment of Fort River (Massachusetts, USA) is presented. Primary production in this fourth order stream exceeds litter input annually, however ecosystem P/R is 0.5. Respiration in excess of gross primary production is supported by allochthonous organic matter imported from upstream reaches. The relative contribution of organic matter size fractions to stream consumers depends upon biologic lability, rate of input, and residence time in the ecosystem. Particles of seston size (1 μm to 1 mm) are most heavily used by consumers, however dissolved organic matter represents the largest input component. Microorganisms are the predominant consumers in this soft-water, nutrient-poor stream ecosystem. A conceptual model for assessing the processing efficiency of stream ecosystems is presented and discussed in terms of several headwater to estuary gradients.

The role of arthropods in forest ecosystems

Abstract: Terrestrial Phytophagous Arthropods.- 1. The Role of the Mountain Pine Beetle in Lodgepole Pine Ecosystems: Impact on Succession.- 2. The Significance of Phytophagous Insects in the Eucalyptus Forests of Australia.- 3. Resource Utilization by Colonial Lepidoptera Defoliators.- 4. Species Structure of Bumblebee Communities in North America and Europe.- 5. Pollination Energetics: An Ecosystem Approach.- Terrestrial Saprophagous Arthropods.- 6. The Roles of Terrestrial Saprophagous Arthropods in Forest Soils: Current Status of Concepts.- 7. Regulation of Deciduous Forest Litter Decomposition by Soil Arthropod Feces.- 8. Contributions of Cryptozoa to Forest Nutrient Cycles.- 9. Soil Microorganism-Arthropod Interactions: Fungi as Major Calcium and Sodium Sources.- 10. Ant Nests as Accelerators of Succession in Paraguayan Pastures.- 11. Community Structure of Collembola Affected by Fire Frequency.- 12. Saprophagous Organisms and Problems in Applied Resource Partitioning.

Nutrient movement through western hemlock- western redcedar ecosystems in

Abstract: A calibrated watershed study was established in a Tsuga heterophylla-Thuja plicata- Pseudotsuga menziesii forest in the Coastal Western Hemlock biogeoclimatic zone in southwestern British Columbia to study the effects of clearcut logging and broadcast slashburning on ecosystem biogeochemistry. Water was sampled regularly at the following stages in its passage through a forest-watershed ecosystem: (1) Precipitation above the forest; (2) canopy throughfall; (3) surface runoff (overland flow); (4) forest floor leachate; (5) mineral soil leachate near the bottom of the rooting zone; (6) groundwater; and (7) stream water. All samples were analyzed for K+, Nat, Mg2 , Ca2 , Fe2 , Mn2 , Al13+, NH4+, C'-, P043-, NO3-, SO42-, dissolved SiO2, pH, alkalinity (as bicarbonate), and electrical conductivity. There was a general increase in chemical concentrations as water entered and moved vertically down through the system to maximum values in forest floor leachate. This was followed by a decrease to minimum values in groundwater, with a slight increase again in stream water. The pH increased steadily from a low in throughfall to maximum values in stream water. These changes in solution chemistry are discussed in relation to ecosystem nutrient cycling processes. Chemical concentrations, pH, and electrical conductivity were generally highest in late summer and early autumn and lowest in winter and early spring. This pattern generally occurred throughout the system and was attributed to seasonal cycles of geological and biological activity, and to rainfall patterns. Data from this study are consistent with the current theory explaining the chemistry of solutions passing through soil.

Nutrient cycling in a Carex lacustris wetland

Abstract: Seasonal changes in aboveground and belowground life history of Carex lacustris were determined and used to study primary production and nutrient cycling in the ecosystem. Seasonal aboveground prod...

Monitoring terrestrial ecosystems by analysis of nutrient export

Abstract: Current methodology for environmental impact assessment relies heavily on population parameters to detect ecological effects of perturbation. We believe that recent advances in ecosystem analysis permit the identification of monitoring points that reflect changes in the total system. Focusing on mechanisms of ecosystem homeostasis, we suggest soil nutrient loss as a sensitive, holistic measure of ecological effects. In three separate studies, attempts were made to detect the effects of toxic substances by monitoring relevant population parameters. In each case, disturbance could be detected in nutrient cycling, but no significant change was evident in the population/community parameters. These results indicate that indices of total ecosystem function may be feasible.

Forested wetlands for water resource management in southern Illinois

Abstract: FORESTED WETLANDS FOR WATER RESOURCE MANAGEMENT IN SOUTHERN ILLINOIS 1 I 1 ) A 30 ha cypress tupelo (Taxodium distichum Nyssa aquatics) , floodplain swamp in Southern Illinois was studied for its hydrologic, biogeochemical and ecological characteristics. The hydrology, water chemistry, sediment dynamics and ecosystem productivity were described for the swamp and interactions with the adjacent Cache River were emphasized. A representative flood in the spring spilled water and sediments from the river to the swamp, temporarily reversing the normal flow of water from the swamp to the river. The annual hydrology budget for the swamp showed inflows of 7'4.4 cm throughfall, 63.9 cm runoff, and 21.9 cm groundwater; the outflows were 7'2.8 cm evapotranspiration, 54.9 cm surface outflow, and 21.0 cm groundwater, the latter two draining to the river. Loading rates for several chemical parameters were calculated from the swamp to the river and water chemistry of the swamp and river was contrasted. Primary productivity measurements showed high rates when the floating duckweed was included; cypress productivity was shown historically to be related to amount of flooding. A phosphorus budget was determined for the swamp and this indicated that the flooding river contributed over 10 times the phosphorus to the swamp as was discharged the rest of the year. Mitsch, W. J., C. L. Dorge, and J. R. Wiemhoff FORESTED WETLANDS FOR WATER RESOURCE MANAGEMENT IN SOUTHERN ILLINOIS Final report to the Water Resources Center, University of Illinois, Urbana, 197'7'.

Phosphorus in the Soil-Plant-Animal Ecosystem

Abstract: A compartmental model of phosphorus in soil-plant-animal ecosystem is described. It consists of 17 compartments, five in soil, six in plant, three in above ground fauna and three in soil organisms and microorganisms. Common amounts and rates of turnover in each of these compartments is presented. Though the total amount of P in the ecosystem is large, only a very small part of it is being cycled, and presented data show that removal of P from an agricultural pastoral ecosystem is very slight. Most of the available phosphorus which is absorbed by plant roots is gradually fixed in forms of long-range unavailability, both by plants and by animals. This process of biological fixation is counterbalanced mainly by the activity of soil microorganisms. Quantities of input-output of P in intensive pastoral ecosystems are also presented, and some agronomical and ecological implications are considered. The manipulation of soil microorganisms and change towards more desirable P releasing strains or species may decrease need of fertilization, lower the risk of eutrophication and enhance productivity of such ecosystems. Such manipulations, however, can be achieved only after appropriate research.

Neue14C-daten aus Marokko und Spanien und ihre aussagen for die relief- und bodenentwicklung im holozän und jungpleistozän

Abstract: Summary During the Late Glacial a reddish-brown soil with irregular layers of calcareous induration in the C-horizon was formed in Southern Morocco. This period was followed by the Early Rharbien, during which there was little geomorphic activity on the slopes, with the accumulation of predominantly fine material in the valleys. In the Middle and Upper Rharbien there were recurring changes involving periods marked by intensive soil formation (black soils) and a significantly higher ground-water table on the one hand (= periods of geomorphodynamic stability) and periods characterized by the transportation of coarse material on the slopes and along the valley floors on the other (periods of geomorphodynamic activity). Given a sufficiently dense vegetation, the climatic conditions obtaining at present favour soil formation (= very little geomorphodynamics on the slopes). However, owing to man's disruption of the ecosystem the prevailing feature today is the transportation of predominantly fine material on the slopes and along the valley floors. The soil erosion and transportation of coarse material which occurred during the climatically induced periods of geomorphic activity were much more intense than those occurring under the present man-modified morphoclimatic regime.

A large indoor tidal mud-flat ecosystem

Abstract: This paper presents a technical description and some preliminary results of a relatively large experimental tidal mud-flat ecosystem, constructed in parallel set-ups in the experimental aquarium of the Nederlands Instituut voor Onderzoek der Zee (NIOZ). The system was build in 1975, filled with sea-water and natural sediment from a typicalArenicola marina habitat. After introducing micro-phytobenthos and juvenileA. marina, the development in both systems, without correcting interventions, were followed for about two years. Studies on nutrient concentrations and organic matter, primary productivity, fluctuations in biomass, density of secondary producers and activity of micro-organisms reveal the systems to be self-pertaining and fairly stable. The study of assemblages of hardy inhabitants of the stressful intertidal environment seems to be a promising starting point for further micro-system research.

Nitrogen Fixing Lichen Roles from Desert to Alpine in the Sangre de Cristo Mountains, New Mexico

Abstract: Lichens containing blue-green algae were measured by transects and reconnaissance in six major temperate vegetation types to estimate possible significance in annual nitrogen budgets and patch dynamics within ecosystems, and to estimate how a functional ecosystem attribute, i.e. nitrogen fixation, correlates with vegetation structure. Lichen cover was negligible in sagebrush desert, pinyon-juniper woodland, ponderosa pine forest and alpine tundra, but averaged 72 m2ha-1 in Douglas fir forest and 33 m2ha-1 in sprucefir forest. North slopes of Douglas fir forest had the highest average cover, 130 m2ha-'. All macrolichens were terrestrial species of Peltigera with P. canina the overwhelming dominant. Based on published laboratory nitrogen fixation rates, lichens probably provide a significant input to the total annual nitrogen budget in the Douglas fir north slope forests and possibly in the spruce-fir forests. A feedback loop relating the role of nitrogen fixing lichens to patchiness within ecosystems is hypothesized. Nitrogen fixing lichens correlate poorly with vegetation structure. Excluding the cold alpine tundra, moisture is considered the primary determinant of nitrogen fixing lichen abundance. Nitrogen fixation by lichens containing blue-green algae is believed widespread in many terrestrial ecosystems (Rogers et al., 1966; Fogg & Stewart, 1968; Denison, 1973; Henriksson & Simu, 1971; Hitch & Stewart, 1973; Alexander & Schell, 1973; Crittenden, 1975; Forman, 1975). The importance of the fixed nitrogen and its roles in the ecosystem are at present largely uncertain due to the paucity of quantitative studies on the distribution of nitrogen-fixing lichens. Nitrogen from lichens may play a significant role in the annual nitrogen budget of an ecosystem by affecting primary productivity and nutrient recycling rates, compartment sizes and outputs. Denison (1973) and Pike et al. (1972) measured the biomass of epiphytic lichens in a tall, wet Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] forest in Oregon and, using two methods, estimated a nitrogen input of 1.8 or 10 kg N ha-1 yr-1. 1 We greatly appreciate Eustaquio Castro-Mendoza for transportation and sampling aid in the field, and James R. Gosz for comments on the manuscript. We also are grateful to William F. Mahler and Ronald K. Wetherington for countless courtesies and stimulation while the research was in progress at the Ft. Burgwin Research Center, Southern Methodist University, Taos, New Mexico 87557. 2 Department of Botany, Rutgers University, New Brunswick, New Jersey 08903. 3 Department of Biology, Southern Methodist University, Dallas, Texas 75275. This content downloaded from 157.55.39.102 on Mon, 03 Oct 2016 05:17:12 UTC All use subject to http://about.jstor.org/terms 562 THE BRYOLOGIST [Volume 80 Forman (1975) measured lichen cover and biomass in a tropical montane rainforest in Colombia and using published laboratory nitrogen fixation rates crudely estimated an input of 1.5-8 kg N ha-1 yr-1. Becker et al. (1977) found nitrogen fixing lichen biomass in a 2.7 ha North Carolina oak forest to average 0.02 kg ha-1, with a maximum 0.18 kg ha-1 for a moist section, and concluded that lichens cannot be significant contributors of nitrogen to the forest as a whole. Other studies have measured or estimated nitrogen fixation of lichen patches or microsites within an ecosystem. For example, some samples within an ecosystem were reported to have high nitrogen fixation rates in a moist mild tundra in Iceland (Crittenden, 1975), a tundra at Point Barrow, Alaska (Alexander & Schell, 1973), Antarctic tundras (Fogg & Stewart, 1968; Horne, 1971), several temperate sites in Great Britain (Hitch & Stewart, 1973), a New Mexican desert (Shields et al., 1957), an Arizona desert (Cameron & Fuller, 1960) and an Australian arid zone (Rogers et al., 1966). A second role of nitrogen produced by lichens, unlike atmospheric nitrogen input, may be in producing environmental heterogeneity within the ecosystem and the consequent patchiness in distribution of organisms. In the American tropics the abundance of nitrogen fixing lichens appears to drop off sharply with decreasing moisture (Forman, 1975). Hitch and Stewart (1973) documented experimentally the overriding importance of moisture deficits in limiting nitrogen fixation by lichens. To better understand which ecosystems may depend on biological nitrogen input, the abundance of lichens in a broad spectrum of ecosystems needs study, especially with respect to moisture gradients. In the broader context of relating ecosystem structure and function, such a study might permit comparison of this functional attribute (nitrogen fixation) with a range of different ecosystem or vegetation structure. Gosz (1975) studied the nutrient and hydrologic dynamics in a spectrum of ecosystem types in the Sangre de Cristo Mountains of New Mexico and found atmospheric nitrogen input varied with elevation as a result of large quantities of precipitation at high elevations and of dust at low elevations. Nitrogen output in stream water varied elevationally as a result of a complex of six factors. Nutrient loss was generally minimal in the intermediate elevation, highly productive Douglas fir forest. The objective of this study was 1) to determine the amount of nitrogen fixing lichens in major vegetation types of the Sangre de Cristo Mountains of New Mexico and 2) to estimate whether or not lichens may be significant in the nitrogen budget or patchiness of terrestrial ecosystems of southwestern North America, and whether or not this functional ecosystem attribute, nitrogen fixation, is related to vegetation structure or climate.

An outdoor model simulating a Baltic Sea littoral ecosystem

Abstract: Plastic pools (surface6.6m2, volume4.2 M3) were equippedwith aflow-through system providing 2.5 1 min-1. Except for fish predators the main components of the flora and fauna of the Baltic littoral zone were introduced into the pools to form a model of the ecosystem. During 8 weeks the macroscopic epifauna and infauna of the bladder wrack Fucus vesiculosus L. were found to be qualitatively and quantitatively fairly stable, and the number of aerobic heterotrophic bacteria showed little variation. Oxygen concentration, temperature and pH were recorded and compared with values measured in the littoral zone. The results indicate good agreement between the characters of the model system and of the natural littoral ecosystem. This together with the observed stability and the possibilities forcontrollingand measuringthe conditions inthe system makes us believe that the model is a valuable tool for assessing toxic effects on the littoral ecosystem.

The development of a benthic ecosystem

Abstract: The development of a benthic ecosystem on a sandy bottom at 3 m depth in the saline Lake Grevelingen, The Netherlands, is described. The development started after the closure of the former Grevelingen estuary and was followed for 4 1/2 years. Ecosystem attributes studied were biomass, secondary production, production/biomass ratio, type of food chains, species diversity, pattern diversity, size of organisms, type of life-cycles, and r- and K-selection. The results are discussed in relation to E. P. Odum's (1969) theory of ecosystem development.

Biomass and nutrient distribution patterns in a young Pseudotsugamenziesii ecosystem

Abstract: Calculations are presented giving biomass and quantities of nitrogen, phosphorus, potassium, calcium, and magnesium contained in soil, understory vegetation, and standing arboreal components of a low-site, immature Pseudotsugamenziesii (Mirb.) Franco ecosystem on southern Vancouver Island. For the standing arboreal crop, biomass and elemental content of the foliage, live and dead branches, wood, bark, and total tree were estimated, using the formula logeY = a + b logeD2H, where D = diameter breast height and H = total tree height.The soil component contained over 70% each of the total organic matter biomass and nitrogen, calcium, and magnesium content in the ecosystem. Although the soil also contained large quantities of potassium and phosphorus, the vegetative component significantly increased in importance with regard to these two elements. Biomass and nutrient distribution patterns within the standing arboreal crop are discussed in terms of elemental concentrations and distribution between components o...

The fate of oil in a model ecosystem

Abstract: With the increasing number of oil spills, research on the determination of immobilization rates of oil at sea has increased. Most investigations have concentrated on such isolated problems as the ability of bacteria to grow on oil, the dissolution of certain fractions of oil and so on. But oil spills at sea are extremely complex events, and the fate of the oil has to be dealt with in a \"systems analytical\" way. This study with simulated oil spills was performed in an attempt to gain a more comprehensive understanding of the processes involved in the oil's disappearance. A theoretical model describing the fate of oil at sea was set up, using the \"Odum energy circuit language\" . To evaluate the hazards of oil spills, rates of degradation must be determined. But to do so with any accuracy, a number of dependent and independent factors bearing on the ultimate fate of oil have to be identified. Energy flow models may be an important tool for obtaining a better understanding of these matters.

Ecosystem research in the tropics

Abstract: Perhaps the biggest problem when discussing ecosystem research is, just what is ecosystem research, and how does it differ from other branches of biology? A traditional definition of ecology is that it is the study of interactions between organism and environment. Platt (1974) and Jordan (1975) have argued that this definition is inadequate, because a large portion of all biological and agricultural research and a significant fraction of medical and engineering studies can be construed to be studies of the interaction between organism and environment, whether or not the studies are really ecological. For example, a sewage engineer might convince a local town council that he is an ecologist because he studies interaction between bacterial concentrations and river flow, and therefore he could claim competence to prepare an environmental impact statement on the effect of sewage outfalls from new housing developments on the stream that passes through the town. We would argue that he is not competent because ecological problems resulting from sewage disposal are not limited to bacterial concentrations, but include such phenomena as eutrophication and resulting changes in fish populations, and recreational and economic use of the unpolluted river. If "the study of interactions between organisms and environment" is an inadequate definition of ecology, because many diverse types of scientists study such interactions, what then is the unit of study that is unique or basic to ecology? One system of classifying units of biology is the hierarchical approach. In this system, for example, the basic unit of study for cytologists is the cell, and the basic unit of study for the morphologist is the organ. For ecologists, the basic but it must have definable limits inside of which there are integrated functions. ecosystems." If our definition of ecology is "the study of ecosystems," we must then define ecosystems. An ecosystem is an integrated unit, consisting of interacting plants and animals whose survival depends upon the maintenance of biotic and abiotic structures and functions. The unit does not necessarily have to be isolated, but it must have definable limits inside of which there are integrated functions. What are these ecosystem functions? There are three functions upon which ecosystem ecologists focus their attention: energy flow; nutrient cycling; and water flux. Nutrients, energy, and water also are studied by physiologists, but what sets ecosystem ecology apart is the structure that supports these functions. Physiologists study flows of energy, nutrients, and water in individual organisms, whereas ecologists study them on an ecosystem scale. In using this definition of ecology we do not mean to say that the only truly ecological studies are those which follow energy, nutrients, and water through

Environmental Impacts of Precipitation Management: Results and Inferences from Project Skywater

Abstract: Recent completion of several research projects into weather modification impacts on the environment provides an opportunity for placing this subject in a new perspective. Studies of physical and biological processes relating precipitation and ecosystem changes show relatively few discernible effects, all of them minor in nature and magnitude. Direct effects of nucleating agents no longer appear consequential Since no acute problems have surfaced, the focus is likely to shift to possible long-term effects on ecosystems as a whole, where changes associated with natural precipitation gradients and climatic fluctuations provide a model for those to be expected from precipitation management. The weakness of environmental impacts of weather modification compared to the consequences of other human actions renders it unlikely that these impacts will be decisive within a behavioral framework.