Showing papers on "Ecosystem published in 1983"

Vegetation of the Earth and Ecological Systems of the Geobiosphere

Abstract: We shall limit our observations to the conditions in natural ecosystems, since it would be beyond the scope of this book to embark upon a consideration of secondary, man-made ecosystems. 2. Classification of the Geo-biosphere into Zonobiomes The biosphere is the thin layer of the earth's surface to which the phenomena connected with living matter are confined. On land, this comprises the lowest layer of the atmosphere permanently inhabited by living organisms and into which plants extend, as well as the root-containing portion of the lithosphere, which we term the soil. Living organisms are also found in all bodies of water, to the very depths of the oceans. In a watery medium, however, cycling of material is achieved by means other than those on land, and the organisms (plankton) are so different that aquatic ecosystems have to be dealt with separately. The biosphere is therefore subdivided into (a) the geo-biosphere comprising terrestrial ecosystems, and (b) the hydro-biosphere, comprising aquatic ecosystems, which is the field of hydrobiologists (oceanographers and limnologists) . Our studies are confined to the geo-biosphere (Walter 1976), which constitutes the habitat of man and is, therefore, of special interest. The prevailing climate, being the primary independent factor in the environment, can be used as a basis for further subdivision of the geo-biosphere since the formation of soil and type of vegetation are dependent upon it (see p. 3), and it has not yet been substantially influenced by man.

Interbiome comparison of stream ecosystem dynamics

Abstract: Studies were conducted in four distinct geographic areas (biomes/sites) in northern United States to examine changes in key ecosystem parameters: benthic organic matter (BOM), transported organic matter (TOM), community production and respiration, leaf pack decomposition, and functional feeding-group composition along gradients of increasing stream size. Four stations ranging from headwaters (1st or 2nd order) to midsized rivers (5th to 7th order) were examined at each site using comparable methods. The results for each parameter are presented and discussed in light of the River Continuum Concept of Vannote et al. (1980). The postulated gradual change in a stream ecosystem's structure and function is supported by this study. However, regional and local deviations occur as a result of variations in the influence of: (1) watershed climate and geology, (2) riparian conditions, (3) tributaries, and (4) location-specific lithology and geomorphology. In partic- ular, the continuum framework must be visualized as a sliding scale which is shifted upstream or downstream depending on macroenvironmental forces (1 and 2) or reset following the application of more localized "micro"-environmental influences (3 and 4). Analysis of interactions between BOM and TOM permitted evaluation of stream retentiveness for organic matter. Headwaters generally were most retentive and downstream reaches the least. Estimates of organic matter turnover times ranged between 0.2 and 14 yr, and commonly were 1-4 yr. Both turnover times and distances were deter- mined primarily by the interaction between current velocity and stream retention. Biological processes played a secondary role. However, the streams varied considerably in their spiraling of organic matter due to differences in the interplay between retentiveness and biological activity. Differences in the relative importance of retention mechanisms along the continuum suggest that headwater stream ecosystems may be functionally more stable, at least to physical disturbances, than are their inter- mediate river counterparts.

Productivity and nutrient cycling in taiga forest ecosystems

Abstract: This paper considers the productivity and nutrient cycling in examples of the major forest types in interior Alaska. These ecosystem properties are examined from the standpoint of the control exert...

Stability of Stream Ecosystems

Abstract: The ability of ecosystems to recover from external disturbances, that is, their stability, is a fundamental property of these systems. Quantification of the ability for various ecosystems to recover and understanding of the mechanisms behind stability are currently areas of major ecological research. In this paper we present an overview of how the stability concept has been used in ecology and a more specific discussion of the application of these ideas to stream ecosystems. This is followed by a case study in which we have been observing the stability of small streams in response to watershed logging and comparing stream stability to stability of the adjacent forest ecosystem.

Contribution of mycorrhizae and soil fungi to nutrient cycling in a Douglas-fir ecosystem

Abstract: The allocation of biomass and nutrients (N, P, K, Ca, Mg) was measured from August 1976 to September 1978 in a young, second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand in the Or...

The Biogeochemical Cycle of Silicon in Two Temperate Forest Ecosystems

Abstract: The biogeochemical cycle of silicon was modelled in two temperate forested ecosystems with the help of four natural reservoirs: vegetation, soil organic matter, soil minerals and soil solutions. Silicon, like potassium, calcium and manganese, is a very good tracer of the functioning of forest ecosystems: deciduous forest ecosystems are characterized by moderate weathering release and geo chemical drainage, and by a strong biological cycle (85 % of the soluble silicon is derived from the soil biogenic silica). In contrast, coniferous forest ecosystems have a weak biological cycle and a strong silicon weathering release flow (85 % of the soluble silicon is derived from the crystalline soil minerals).

Phyto-Zooplankton Community in Coastal Waters of Western Sweden -An Ecosystem Off Balance?

Abstract: ABSTFUCT: A baseline study of the phytound zooplankton community was carried out from 1978 to 1981 in, what was supposed to be, a relatively undisturbed fjord on the west coast of Sweden. Heavy phytoplankton blooms were found during spring and autumn. Chlorophyll a and cell numbers were far above normal. Extremely low zooplankton biomass during the spring bloom and high abundance of scyphomedusae (which preyed on zooplankton during the summer) resulted in low grazing pressure and probably led to increased sedimentation of organic matter. Oxygen deficit has occurred in bottom waters of the fjord in the absence of adequate exchange. It was not possible to determine whether this series of events is due to natural fluctuations or man-made influences.

Increasing atmospheric carbon dioxide: possible effects on arctic tundra

Abstract: Cores of wet coastal tundra collected in frozen condition in winter were used as microcosms in a phytotron experiment that assessed the effects of doubling the present atmospheric CO2 concentration, increasing temperature, and depressed water table on net ecosystem CO2 exchange. Doubling atmospheric CO2 had less significance in regard to net carbon capture or loss in this ecosystem as compared to the significant effects of increased temperature and lowered water table level. Both of the latter are to be expected as atmospheric CO2 increases in the Arctic.

Impact of Fire on Nutrient Cycles in Mediterranean-Type Ecosystems with Reference to Chaparral

Abstract: Although there is a large literature describing the effects of fire on biogeochemical cycles of nutrients, no studies have quantified the ecosystem effects of fire on intersystem fluxes of nitrogen or other nutrients through a full successional cycle (see reviews of fire-nutrient interactions in Viro 1974; Woodmansee and Wallach 1980; Rundel 1981, 1982). The nitrogen balance of ecosystems with major portions of biomass below ground or with low above-ground coverage (grasslands, tundra, deserts) is not generally effected by fire. Low-intensity ground fires in many forest ecosystems likewise do not have a major impact on nutrient cycles. Chaparral and other mediterranean-type ecosystems, however, have characteristic high-intensity fires at relatively frequent intervals. These fires burn off much of the above-ground biomass and have very large immediate effects on output fluxes of nutrients from the ecosystem and smaller secondary effects on both outputs and inputs of nutrients through successional cycles. There are virtually no quantitative data available for the site and dynamics of ecosystem pools of nutrients during such fires.

Ecosystem processes : mineral cycling, productivity and man's influence

Abstract: D.- 1 Nutrient Allocation in Plant Communities: Mineral Cycling in Terrestrial Ecosystems.- 2 Nutrient Cycling in Freshwater Ecosystems.- 3 Nutrient Cycling in Marine Ecosystems.- 4 Modeling of Growth and Production.- 5 Productivity of Agricultural Systems.- 6 Productivity of Grassland and Tundra.- 7 Productivity of Desert and Mediterranean-Climate Plants.- 8 Productivity of Temperate, Deciduous and Evergreen Forests.- 9 Productivity of Tropical Forests and Tropical Woodlands.- 10 Phytoplankton Productivity in Aquatic Ecosystems.- 11 Effects of Biocides and Growth Regulators: Physiological Basis.- 12 Effects of Biocides and Growth Regulators: Ecological Implications.- 13 Eutrophication Processes and Pollution of Freshwater Ecosystems Including Waste Heat.- 14 Ecophysiological Effects of Atmospheric Pollutants.- 15 Ecophysiological Effects of Changing Atmospheric CO2 Concentration.- 16 Man's Influence on Ecosystem Structure, Operation, and Ecophysiological Processes.- Author Index.- Taxonomic Index.- Subject Index for Parts A-D.

Simulating carbon accumulation in northern ecosystems

Abstract: A model of the carbon balance in arctic and boreal forests has been developed to estimate the effects of higher carbon diox ide levels in the atmosphere on northern ecosystems. The model predicts that northern ecosystems should accumulate 5-10% of the carbon added to the atmosphere each year. Ac cumulation rates should increase by 2-8 times by year 2020 depending on the availability of nutrients. The rates of change in several processes are only estimates. The predictions are subject to large errors because of the complexity of ecosys tems interactions and the absence of data on the long-term ef fects of higher temperature and atmospheric CO2 levels. More differentiation of plant types, more feedback interactions, and more stochastic variations could improve the model. How ever, the results show that carbon accumulation in northern ecosystems is a significant fraction of the terrestrial carbon flux. The response of these systems is therefore important in predicting global carbon balance.

Termitaria: Nutrient Patchiness in Nutrient-Deficient Rain Forests

Abstract: Termite population parameters and termite nest-nutrient content are compared among three nutrient-deficient vegetation types along the Rio Negro. Termite population parameters are positively associated with forest productivity, biomass, stature, and soil fertility. As calculated from these population parameters, a minimum of three to five percent of total litter is consumed by termites. However, the high spatial variance, or patchiness, of termite consumption and nutrient concentration may be much more important to forest dynamics. Termitaria form rich nutrient patches that contrast significantly with the highly weathered soils of the region. Termitaria are abandoned at a rate of 165 ? 66 nests ha-' yr-', providing abundant and potentially important microsites for treeseedling establishment. There is a consistent gradient of nutrient concentration: soils < litter < termitaria, supporting the hypothesis that social insects can concentrate resources, accentuating habitat patchiness and species diversity. "A major determining factor in forest composition and succession is probably where the dog died." (Attributed to Earl Stone, Forest Soil Scientist, Cornell University.) TROPICAL ANALOGIES TO THIS APHORISM may be more exotic, but the concepts of microsite variation and the importance of localized decomposition are clearly applicable. The importance of termites as major tropical decomposers has been declared or assumed for centuries. Only recently has quantitative evidence been available to support these contentions (Lee and Wood 1971, Brian 1978). Tropical ecosystems vary greatly in structure and function. Extreme habitats (e.g., blackwater rivers, Janzen 1974) may necessitate extreme adaptation. Within tropical forest ecosystems growing on nutrient-poor substrates, intriguing mechanisms for nutrient conservation and exploitation have evolved (Herrera et al. 1978). While termites are ubiquitous in such habitats, data on their significance as decomposers are lacking. This study concerns the role of termites in the forests along the Rio Negro, a blackwater tributary of the Amazon.

Particle-Size-Conversion Efficiency and Contaminant Concentrations in Lake Ontario Biota

Abstract: The particle-size-conversion efficiency (log food consumption/production divided by log predator prey size ratio) is shown to be directly related to the relationship between the concentration of persistent contaminants accumulated primarily through the food chain and body size for organisms in pelagic ecosystems. The difference between particle-size-conversion efficiency for biomass and that for the contaminant gives the slope of the relationship between log contaminant concentration and log body size. This provides a useful theoretical framework for analyzing contaminant concentrations in aquatic biota without the need for specifying trophic level but still incorporating the idea of food chain accumulation. Concentrations of PCB, DDT, and mercury were examined in aquatic organisms from Lake Ontario, ranging in size from zooplankton to large salmonids (a 108 -fold range in dry weight). The slope of the double log plot of concentration versus weight varied from 0.20 to 0.22 for PCB and DDT and was approxim...

Decomposition and mineralization processes in mediterranean-type ecosystems and in heathlands of similar structure

Abstract: The major resources of plant mineral nutrients in all soils exist as complex molecular aggregates from which they must be released before they become available for utilization by the vegetation. Since the rate of nutrient release often limits the primary productivity of an ecosystem, it is of fundamental importance to understand the major processes involved through decomposition and mineralization in the maintenance of nutrient cycling phenomena.

Evaluation of economic forest ecosystem services in China

Abstract: This paper quantitatively evaluated the economic forest ecosystem services in the provinces of China in 2003, based on the long-term and continuous observations of economic forest ecosystems in this country, the sixth China national forest resources inventory data, and the price parameter data from the authorities in the world, and by applying the law of market value, the method of substitution of the expenses, and the law of the shadow project. The results showed that in 2003, the total value of economic forest ecosystem services in China was 11763.39 x 10(8) yuan, and the total value of the products from economic forests occupied 19.3% of the total ecosystem services value, which indicated that the economic forests not only provided society direct products, but also exhibited enormous eco-economic value. The service value of the functions of economic forests was in the order of water storage > C fixation and O2 release > biodiversity conservation > erosion control > air quality purification > nutrient cycle. The spatial pattern of economic forest ecosystem services in the provinces of China had the same trend with the spatial distribution of water and heat resources and biodiversity. To understand the differences of economic forest ecosystem services in the provinces of China was of significance in alternating the irrational arrangement of our present forestry production, diminishing the abuses of forest management, and establishing high grade, high efficient, and modernized economic forests.

Nutrient studies in relation to habitat types and canopy dieback in the montane rain forest ecosystem, Island of Hawai'i.

Abstract: A soil and foliar nutrient analysis was carried out in the Hawaiian Metrosideros rain forest for the purposes of elucidating a previously published physical habitat classification and for finding an explanation for the widespread canopy dieback, which is not caused by a biotic agent in this ecosystem. Soil elements analyzed were C, N, P, Ca, AI, Mn, Fe, and other parameters such as pH. Foliar analysis was restricted to N, P, Ca, Mn, and Fe and assessed only for the canopy M. polymorpha and its major associate, the tree ferns, in the undergrowth. It was found that the earlier recognized two-way breakdown into oligotrophic and eutrophic nutrient regimes had to be enlarged for the habitat classification to a mesotrophic category. Young, deep-ash soils were recognized as mesotrophic on account of their moderate pH and high Ca levels, but they showed severe limitations in available nitrogen and phosphorus that were reflected also in the foliage. Intermediate-aged (1000 yr) ash soils were found to be nutritionally well supplied and balanced and thus considered eutrophic, while older ash soils were designated as oligotrophic on account oftheir extreme acidity and associated higher and potentially toxic levels of soluble AI, Mn, and Fe. Except for the mesotrophic 'a'a lava site, other shallow rock outcrop habitats on pahoehoe were recognized as oligotrophic, because of very low available N and high acidity and, in the poorly drained sites, also high levels of potentially toxic metals. The bog habitats had the highest levels of potentially toxic metals, but surprisingly moderate levels of available Nand P. The canopy dieback phenomenon cannot be entirely explained from the nutrient imbalances found in most of the substrate types, but these imbalances are considered contributory in the sense that they become increasingly stressful with stand development, thereby decreasing tree vigor and predisposing stands to dieback. THE WIDESPREAD CANOPY DlEBACK in the Hawaiian Metrosideros rain forest was initially considered a biotic disease problem (Petteys, Burgan, and Nelson 1975). However, after intensive research, biotic agents were thought to be of lesser importance (Hwang 1977, Papp et al. 1979), and attention 1 This research was supported in part by National Science Foundation grant DEB 79-10993 and McIntireStennis grant HAW-684 to D. Mueller-Domhois. In addition, a University of Hawaii-East West Center collaborative grant to D. Mueller-Dombois and L. S. Hamilton provided funds for completion of this work. Manuscript accepted 5 October 1983. 2University of Hawaii at Manoa, Department of Botany, 3190 Maile Way, Honolulu, Hawaii 96822. was drawn to soil nutrients. Kliejunas and Ko (1974) found that dying trees could be revived with NPK fertilizer, but not with application of fungicide. Earlier in this century, a Metrosideros canopy dieback on the island of Maui was also recognized as a nutrient problem rather than a biotic disease problem. Lyon (1909, 1918), a researcher for the Hawaiian Sugar Planters Association, spent several years investigating the Maui dieback. He concluded that native tree stands were dying because of soil toxicity developing with soil aging and poor drainage. Ecological studies carried out on the islands of Hawaii and Maui established that the soils in the dieback territories vary con-

Nutrient Allocation in Plant Communities: Mineral Cycling in Terrestrial Ecosystems

Abstract: In recent years the literature on mineral cycling in terrestrial ecosystems has expanded greatly, and few if any of the major biomes have escaped attention. We do not propose to review this large body of information in detail. Rather, it is our intention to outline the broad features of mineral acquisition, distribution and cycling that apply generally in terrestrial ecosystems, and to highlight several facets of the internal cycle that are vital for community nutrition but which seem to have been rather neglected. Inevitably, we cannot treat all essential elements equally, nor can we deal with the functional aspects of elemental storage and flux in all their complexity. The aboveground components of ecosystems have been studied in great detail, whereas spatial and temporal patterns in soil are but poorly understood. The account that follows is in part, therefore, an attempt to redress this imbalance and consequently is uneven in its treatment of both the static and dynamic attributes of ecosystems.

Effects of Acid Deposition

Abstract: From the view point of the receiving ecosystem, a distinction is made between precipitation deposition and interception deposition. Long term mean values for both kinds of deposition are given for a deciduous and a coniferous forest in Central Europe (Soiling region). Interception deposition exceeds precipitation deposition especially in the coniferous forest. The acidity deposited is to more than 75% due to SO2, NOX contributes less than 20%. Only less than 22% of the acidity is neutralized before reaching the ecosystem. Less than 18% of the acidity is buffered in the ecosystem down to 1 m soil depth. The main fraction of the acidity passes through the ecosystem and will finally acidify the hydrosphere. The two aspects of soil acidification are discussed shortly: leaching of nutrients and release of toxins. Heavy metals from deposition accumulate in the biotic part of the ecosystem. From a balance consideration, taking into account emission rates, deposition rates and the kind and rates of possible reactions of strong acids in the ecosphere, it is concluded that the emission of strong acid formers like SO2 and NOX leads to the poisening of the ecosphere.