Showing papers on "Ecosystem published in 1975"

Ecosystem Succession and Nutrient Retention: A Hypothesis

Abstract: velopment of ecosystems were presented in Odum's very important paper, "The Strategy of Ecosystem Development" (1969). This series of hypotheses has helped to organize thinking on ecosystem dynamics and to focus further research. In this paper, we wish to examine one of these hypotheses, which suggests that as ecosystems mature their ability to conserve nutrients increases. Our objective is to show through logical examination of characteristics of succession, and through presentation of critical field data, that this hypothesis cannot be stated quite so simply. We also intend to show that uncritical utiliza-

The Resource Limitation of Trophic Levels in Tropical Grassland Ecosystems

Abstract: One feature of terrestrial ecosystems that is becoming widely recognized is the small proportion of primary production, measured on an annual basis, that is consumed by herbivores.t In grassland systems Wiegert & Evans (1967) found that consumption rarely exceeded 10% of the primary production and the only exceptions appeared to be in the East African tropical grasslands supporting large ungulate populations, where it was roughly estimated that between 30 and 60% of the primary production was consumed. But with further information Phillipson (1973) put forward a tentative model for the Serengeti ecosystem in Tanzania, and in this model only 18% of the net primary production was utilized by the herbivores. In woodland systems similar results have emerged: herbivores consumed less than 70 of the tree production in a deciduous woodland (Varley 1970), and Reichle et al. (1973) found that insects consumed only 2-6% of the primary production in a forest canopy. The more restricted studies of the energy flow in small mammal communities have all found that less than 20% and sometimes only 2% of the primary production is utilized (Grodzinski 1963, 1971; Grodzinski et al. 1970; Ryszkowski 1970). Slobodkin, Smith & Hairston (1967) have summarized other similar results all of which show that less than 10% of the primary production is consumed.

Tropical Ecological Systems; Trends in Terrestrial and Aquatic Research.

Abstract: 1. Ecological Research in the Tropics.- Physiological Ecology.- 2. Physioecological Problems in the Tropics.- Dynamics of Populations.- 3. Demographic Strategies in Animal Populations: A Regression Analysis.- 4. A Matrix Model of Tree Population Dynamics.- 5. An Analysis of Late Secondary Succession in Species-Rich Tropical Forest.- 6. The Relation Between Rainfall and Mosquito Populations.- Interaction Between Species.- 7. Impact of Sloths on Neotropical Forest Energy Flow and Nutrient Cycling.- 8. Impact of Leaf-Cutting Ants on Vegetation Development at Barro Colorado Island.- Tropical Forest Analysis.- 9. Biomass and Structure in a Central Amazonian Rain Forest.- 10. Root Distribution and Biomass in Three Ivory Coast Rain Forest Plots.- 11. Litter Production in Deciduous Forest near Udaipur (South Rajasthan), India.- 12. Litter Fall and Litter Breakdown in Miombo.- 13. Nutrients in Throughfall and Their Quantitative Importance in Rain Forest Mineral Cycles.- 14. Production, Energy Pathways, and Community Diversity in Forest Birds.- Savannas.- 15. The Structure and Function of a Tropical Savannah Ecosystem.- 16. A Critical Consideration of the Environmental Conditions Associated with the Occurrence of Savanna Ecosystems in Tropical America.- 17. Effect of Fire on Organic Matter Production and Water Balance in a Tropical Savanna.- 18. Net Primary Production in Grasslands at Udaipur, India.- Tropical Water Bodies.- 19. Tropical Rivers as Expressions of Their Terrestrial Environments.- 20. Productivity, Biomass, and Population Dynamics in Amazonian Water Bodies.- 21. Some Aspects of the Ecology of Tropical Estuaries.- 22. Diurnal Rates of Photosynthesis, Respiration, and Transpiration in Mangrove Forests of South Florida.- Island Ecosystems.- 23. Some Aspects of Island Ecosystem Analysis.- Applications.- 24. Faunal Equilibria and the Design of Wildlife Preserves.- 25. A Comparison of Soils Under Agriculture and Forests in San Carlos, Costa Rica.

The patterns of rainfall in the Serengeti Ecosystem, Tanzania

Abstract: Summary This paper presents a description of the temporal and spatial distribution of rainfall within the Serengeti Ecosystem, Tanzania. Ecosystem and Regional patterns are discussed with respect to synoptic processes, vegetation zonation, phases of primary production and the distribution and migrations of large mammals.

Toward A Model of Detritus Processing in a Woodland Stream

Abstract: A state—space model for the microbial and abiotic decomposition of detritus in a temperate zone woodland stream is developed. Detritus, defined as nonliving, particulate organic matter and its associated microbial populations, is classified according to particle size and extent of microbial colonization as reflected by community respiration. These categories form a matrix whose entries are detrital biomass; detritus processing in the stream is simulated using transition functions to move biomass through the categories. The model can be coupled to population models of stream invertebrates via removal of detritus from the matrix for detritivore feeding. Simulation results are presented and compared with field data. See full-text article at JSTOR

Canopy Lichens with Blue‐Green Algae: A Nitrogen Source in a Colombian Rain Forest

Abstract: Lichens containing blue-green algae are abundant (13,600/ha; total biomass 5.7 kg/ha) in a Colombian montane rain forest. These noncrustose lichens grow mainly on 3-12 cm diam twigs and small branches, 12-25 m high at the top of the crowns of canopy and subcanopy trees. They are rare below 4 m. Eighty-six % of the lichens contain Nostoc and, based on published laboratory nitrogen-fixation studies of lichenized Nostoc, these lichens fix an estimated 1.5-8 kg N/ha- yr, equivalent to the estimated range of total nitrogen input in precipitation. This lichen phenomenon is probably widespread in rain forests of the American tropics. These results reemphasize the importance of the epiphyte community in the canopy layer of the rain forest ecosystem.

Bird community dynamics and energetics in a northern hardwoods ecosystem

Abstract: One of the central goals of ecology is to understand the organization and functional relationships among natural assemblages of organisms and their complex interaction within ecological systems. Although the structures and productivities of terrestrial plant communities and their role as primary producers have been frequently studied (Whittaker 1970), there is little comprehensive information on whole communities of consumer organisms, especially those such as birds living above ground and often high in forest canopies. This is due in large part to the methodological difficulties of obtaining quantitative data simultaneously on the seasonal and annual fluxes in numbers and energy expenditures of a large number of populations. Recent work has demonstrated, however, that with intensive field investigations, bird community structures can be determined quantitatively (Emlen 1971, 1972; this paper) and that the energy expenditure of freeliving birds can be realistically estimated, using information on avian bioenergetics that has recently become available (Holmes & Sturges 1973). Several studies provide information on the structure and energy flow of individual bird populations, e.g. old field sparrows in winter (Odum, Connell & Davenport 1962), breeding red-winged blackbirds, AgelaEus phoeniceus* (Brenner 1968), and marsh wrens, Telmatodytes palustris (Kale 19653, and tree sparrows Passer montanus (Pinowski 1968) on an annual basis. At the community level, Uramoto (1961) and Karr (1968, 1971) have estimated the populations sizes and energy expenditure of birds breeding in deciduous forest in Japan and in Illinois and Panama, respectively, but their results were not discussed in an ecosystem context. Varley (19703 and Phillipson (19733 have modelled energy pathways through a temperate oak woodland, with emphasis on consumer organisms, although their data on the avian community were very incomplete. The most thorough and comprehensive analysis of avian community structure and energetic role is that of Wiens (1973) for grassland bird communities in summer. Inthis paper, we report some results from 51 continuous months of intensive and quantitative studies of bird community dynamics and energetics in the northern hardwoods ecosystems of the Hubbard Brook Experimental Forest in West Thornton, New Hampshire, U.S.A. The major objectives of this paper are to examine the seasonal and annual Ruxes in bird community composition, absolute population densities, biomass, productivities, and energy expenditures, and to consider the place of birds in the energy flow pathways of northern hardwood forests. A report with procedures for estimating

Effects of species on nutrient cycles and soil change

Abstract: The choice of species to be favoured in forest management is subject to several considerations, among them the possibility of adverse effects on site productivity. Information on this possibility is reviewed from three viewpoints: nutrient cycling, soil genesis and classification, and relatively short-term (i.e. within one generation) changes in soil properties and growth rate. Nutrient cycle models describe flows between soil and plant components of ecosystems but generally can reveal little about variation in nutrient supply over the life of a stand. Profound changes in profile characteristics and mineral weathering occur on a time scale of millennia and can scarcely be expected within a single generation of one or another species. Many reported comparisons of species effects on soil profile development, physical structure, or nutrient status are invalid for a variety of reasons, including inadequate perception of inherent soil heterogeneity. Claims of decreased yields resulting from successive generations of conifers are not borne out by recent studies. Finally, maximum changes in soil due to choice of species appear minor in comparison with the mechanical and chemical impacts associated with present day intensive forest management.

Plants and microorganisms

Abstract: 1. Site Description.- Description of Fennoscandian Tundra Ecosystems.- 2. Abiotic Variables.- Soils of Fennoscandian IBP Tundra Ecosystems.- Climate and Hydrology of Some Fennoscandian Tundra Ecosystems.- 3. Primary Producers.- 3.1. Plant Structure.- Flora and Plant Sociology in Fennoscandian Tundra Areas.- Survey of the Main Plant Communities on Hardangervidda.- Vegetation Mapping at Hardangervidda.- Dispersal and Primary Establishment of Vegetation.- Comparison of Plant Structure on Grazed and Ungrazed Tundra Meadows.- Plant Phenology of Fennoscandian Tundra Areas.- Measurement of Leaf Areas and Leaf Angles of Plants at Hardangervidda, Norway.- 3.2. Biomass and Production.- Plant Biomass and Primary Production of Fennoscandian Subarctic and Subalpine Forests and of Alpine Willow and Heath Ecosystems.- Primary Productivity of Alpine Meadow Communities.- Growth in Populations of Andromeda polifolia on a Subarctic Mire.- 3.3. Plant Processes.- Weight Increase of Some Lichens as Related to Carbon Dioxide Exchange and Thallus Moisture.- CO2 Exchange and Growth of Rhacomitrium lanuginosum and Dicranum elongatum.- On the Effect of Continuous Light on Photosynthesis in Mosses.- Acclimatization Effect in Photosynthesis and Respiration.- CO2 Exchange in Norwegian Tundra Plants Studied by Infrared Gas Analyzer Technique.- Photosynthesis and Respiration of Plants Studied by Field Technique at Hardangervidda, Norway.- The Seasonal Pattern of Photosynthesis of Some Vascular Plants on a Subarctic Mire.- Energy Content and Use of Solar Radiation of Fennoscandian Tundra Plants.- Distribution of 14C Photosynthates in Norwegian Alpine Plants.- Pigment Structure of Vascular Plants, Mosses, and Lichens at Hardangervidda, Norway.- 4. Decomposers.- Decomposition, Microbiology, and Ecosystem Analysis.- Biomass and Production of Soil and Litter Fungi at Scandinavian Tundra Sites.- Microfungal Populations of the Abisko Area, Northern Sweden.- Bacterial Populations of Some Fennoscandian Tundra Soils.- Comparisons ofDecomposition Rates Measured by Means of Cellulose.- Plant Litter Decomposition at Fennoscandian Tundra Sites.- Carbon Losses from Tundra Soils.- 5. Nutrient Cycling.- Nitrogen Fixation in Lichens at Kevo, North-Finland.- Nitrogen Fixation by Bacteria and FreeLiving Blue-Green Algae in Tundra Areas.- Mineral Content of Tundra and Forest Tundra Plants in Fennoscandia.- Analysis of Precipitation at Fennoscandian Tundra Sites.- Organic Compounds in Alpine Plants.- The Input and Significance of Particulate Terrestrial Organic Carbon in a Subalpine Freshwater Ecosystem.

The Structure and Function of a Tropical Savannah Ecosystem

Abstract: The higher levels of biological organization, called ecosystems, are of growing interest to ecologists. Ecosystems are defined as systems of plants and animals interacting together in a given environment. Research on ecosystems can be quite complicated since even the simplest systems have numerous plant and animal species, which show great diversity of size, distribution, rate of biological increase, diet, and so on. These parameters also vary with time, so that it is necessary to account for their heterogeneity in time and space.

Diurnal Rates of Photosynthesis, Respiration, and Transpiration in Mangrove Forests of South Florida

Abstract: The mangrove forests of south Florida extend over an area of 1,750 km2, located primarily within the boundaries of the Everglades National Park and within the region known as the Ten Thousand Islands (Figure 22-1). Davis (1940) described the zonation and succession in some of these areas, and more recent descriptions appear in Craighead (1971). The majority of the literature on mangroves is descriptive; only recently have investigators studied ecosystem function and the role(s) of mangroves in a regional ecosystem. The work of Golley et al. (1962) established baseline information on the primary productivity and respiration for a red mangrove stand in Puerto Rico, and demonstrated its role in exporting organic matter to the adjacent estuarine ecosystem. The regional role of mangrove forest ecosystems in Florida has been documented by Heald (1969) in terms of detritus export, and by Odum (1969) in terms of the role of detritus in the food chains of estuarine and commercial fisheries.

Net Primary Productivity in Tropical Terrestral Ecosystems

Abstract: Ranging from lowland evergreen rain forest to alpine tundra, the variety of terrestrial ecosystems lying within tropical latitudes exceeds that of any other region on earth. Our knowledge of net primary productivity (NPP) rates in tropical ecosystems must be described as fragmentary. The relatively few available data pertain to a diverse assortment of samples subject to different levels of precipitation and disturbance.

Litter arthropod community in a southern Appalachian hardwood forest: numbers, biomass, and mineral element content

Abstract: The biomass, numbers of individuals and mineral content of the arthropod fauna in the litter of a mixed hardwood forest were examined. The biomass values of the litter arthropods were generally higher than in other forests. Possible reasons for higher biomass values are discussed. Potassium and calcium standing crops are compared to those of a Liriodendron forest in Tennessee. With few exceptions the potassium values are comparable. However, there appear to be great differences in the calcium values. INTRODUCTION The forest constitutes an ecosystem in which organic and inorganic elements interact. The basic mineral nutrition of forest vegetation is provided by rock weathering and mineral-laden rain. The forest is charged and recharged by organic products from the vegetation (Spurr, 1964). The nutrient recharging is accomplished to a great extent by litter decomposition which releases the nutrients bound up in the dead plant structural material. Decomposition is accomplished by the activities of both the forest floor microflora and fauna. As organic materials reach the forest floor, they are attacked by the microflora and fauna, releasing nutrient substances, and 40 to 90% of the initial weight may be lost during the 1st year, the actual amount varying with species and locality (Edwards et al., 1970). Witkampl and Olson (1963) showed a nonlinear rate of weight loss by leaf litter during the 1st year, often with an initial rapid loss of weight, possibly due to leaching of soluble materials. This is followed by a slower loss rate during the winter months and subsequent acceleration during spring and summer (Crossley, 1970). Fresh leaf litter may remain unpalatable to soil fauna until the polyphenols in the stem and leaf material are removed (Edwards and Heath, 1963; Satchell and Lowe, 1966), and this may delay faunal attack on the litter for some time. Several studies on the dynamics of litter breakdown by fauna have been reported. Satchell (1967) suggested there may be extensive incorporation of litter into the mineral soils by the feeding of earthworms. 'Research supported in part by the Eastern Deciduous Forest Biome, US/IBP, funded by the National Science Foundation under Interagency Agreement AF-199, 40-193-69, with the U.S. Atomic Energy Commission Oak Ridge National Laboratory, and in part by U.S. Atomic Energy Commission Contract AT-(38-1)-641 with the University of Georgia (D. A. Crossley, Jr.). Contribution No. 147 from the Eastern Deciduous Forest Biome, US/IBP. 2 Present address: Ecology Center, Utah State University, Logan, Utah.

Effect of desert termites on herbage and litter in a shortgrass ecosystem in west Texas.

Abstract: Highlight: The desert termite, Gnathamitermes tubiformans, is an important insect on rangelands in the southwestern United States. Population densities of this insect averaged 2139/m* in the upper 30 cm of soil in a shortgrass community in West Texas over a 3-year period and reached a peak of 9127/m*. The ,live biomass of termites averaged 5.2 g/m* and reached a peak of 22.21 g/m*. In a laboratory study, desert termite workers consumed 2.4% of their live body weight/day of dry buffalograss leaves. In field studies, control of desert termites with insecticide resulted in a 22% increase in standing crop of grass and a 50% increase in litter accumulation by the end of the second growing season after control was initiated. Termite-free plots had almost three times more litter than termite-infested plots after four growing seasons. Desert termites accounted for S5% of the disappearance of litter from the soil surface. Ranchers can expect higher population densities of desert termites and hence greater consumption of forage and litter during wet years.

Litter Accumulation Under Calluna Vulgaris on a Lowland Heathland in Britain

Abstract: The pattern of organic matter production by the above-ground vegetation of Calluna heathland in lowland Britain has been described by Chapman, Hibble & Rafarel (1975) and accounts of the overall nutrient budget and root standing crop for the same area are given by Chapman (1967, 1970). The litter layer accumulating on the surface of the soil is important as a storage bank for plant nutrients that can be released by the activity of the decomposers. In an ecosystem where available nutrients are present in limited quantities only and the rate of decomposition is low the litter layer becomes increasingly important in the overall nutrient regime of the system. The litter layer is an important habitat for members of the soil fauna, a high proportion of the biomass of the soil fauna actually living in this layer. In a potentially cyclical system, such as heathland, where the vegetation passes through building, mature and degenerate phases of development, the accumulation and characteristics of the litter layer are important regarding germination and establishment of both Calluna vulgaris (L.) Hull and invading tree and shrub species. This paper attempts to characterize the process of litter accumulation in relation to litter production, general considerations of decomposition, and the release of plant nutrients in the litter layer of an area of lowland heathland in southern Britain (in Dorset). Details of the sites under discussion have been described by Chapman (1967, 1970) and by Chapman et al. (1975).

Nitrogen Fixation by Bacteria and Free-Living Blue-Green Algae in Tundra Areas

Abstract: Combined nitrogen is probably the limiting nutrient factor for primary production in many tundra areas. The removal of combined nitrogen from tundra areas by leaching or denitrification seems limited, and even a small nitrogen input from e.g. nitrogen fixation is important for the nitrogen balance of the ecosystem. The main sources of nitrogen input are biological nitrogen fixation, precipitation and dry deposition. Nitrogen-fixing organisms present in tundra areas are free-living, epiphytic and symbiotic blue-green algae, and free-living and symbiotic bacteria.

Energy Flow through a Bird Community in a Deciduous Forest in Southern Poland

Abstract: The bioenergetic approach to ecosystem function requires the investigation of energy flow through the various components. In many terrestrial ecosystems birds are an important link in the trophic chain, being consumers of the first, second, and/or higher orders. Investigations of energy flow through these homeothermic animals entail many specific methodological difficulties. Bird communities in terrestrial ecosystems usually comprise many species with different population dynamics and phenology. Most bird species of the temperate zone migrate seasonally. To determine the energy requirements of birds under natural conditions, one must take into account the costs of thermoregulation and intensive locomotor activity as well as the cost of reproduction. Therefore, such investigations are laborious. Existing published works include a number of studies concerning energy flow through single species populations (Odum et al. 1962, Kale 1965, Pinowski 1968) or through communities composed of several bird species (Uramoto 1961, Wiens 1973, West and DeWolfe 1974). However, these papers give results covering periods of several months only. Up to now only one complete energy flow study presenting a yearly cycle has been conducted for complete multi-species bird communities (Holmes and Sturges 1973). The purpose of this work was to estimate the yearly energy flow through a multi-species bird community in a deciduous forest in the temperate zone. We did not attempt a complete population and bioenergetical investigation. Energy flow was estimated using field data on the dynamics of bird numbers in the area in 1968 and 1971 and bioclimatic data. Numerous parameters of the biology and physiology (bioenergetics) of birds used were taken from the literature. STUDY AREA AND METHOD

Ecological energetics of decomposer invertebrates in a deciduous forest and total respiration budget

Abstract: The analysis of ecosystems has recently received the increasing attention of investigators as they attempt to characterize the functional dynamics of natural systems by quantifying their component processes and the interconnections of these processes. The ecosystem concept implies that an understanding of the processes and their interactions can provide the ability to predict changes in ecosystem behavior resulting from changes imposed on those processes. While many attributes of ecosystems can be characterized, all are inextricably related to the carbon and mineral element metabolism by organisms composing that system.

Decomposition Processes in the Fishpond Littoral

Abstract: One of the main goals of the IBP was to present quantitative data on the production of biotic components of ecosystems. But estimates of microbial populations in ecosystems are usually rather difficult and open to all sorts of criticism. Despite all inherent uncertainties, in the course of the IBP several authors tried to estimate the microbial biomass in various ecosystems (Kuznetsov and Romanenko, 1966; Clark and Paul, 1970; Aristovskaya, 1972; Parkinson, 1970). Different ways have been suggested of estimating the biomass of bacteria, fungi and actinoycetes from data on their population densities. Such methods are discussed by Parkinson et al. (1971) and Sorokin and Kadota (1972) for terrestrial and aquatic ecosystems respectively.

A Reservoir Cove Ecosystem Model

Abstract: A total ecosystem compartment model of a reservoir cove is described, with emphasis on the fish submodel. Nominal (unperturbed) annual cycles of selected compartments are presented, and results from three perturbation experiments (thermal pollution, eutrophication, piscivore invasion) are summarized. The ability of fishes to influence structure and function of the entire ecosystem (model) is demonstrated, and the role of top trophic levels in controlling the design of ecological communities is discussed. The status and prospects of total ecosystem modeling as a tool for fisheries science are considered.

Pesticide residue dynamics in a forest ecosystem: a compartment model:

Abstract: This paper presents a computer model of the movement of pesticide residues in a forest ecosystem. As such, the paper deals primarily with the potential direct effects on target and nontarget organisms, but does not address the very long-term consequences of restructuring the vegetation in an ecosystem. Simulations using the model trace the movement of two herbicides (2,4,5-T and picloram) through two different environments, one typical of an Oregon forest and the other typical of southern California chaparral. The model is written in DYNAMO.

Soil biota and its role in soil ecology

Abstract: Soil organisms alter soil physical, chemical and biological properties in different ways. The composition and structure of biotic communities at one hierarchical level can influence the spatial heterogeneity of resource at other hierarchical levels, and the latter is supported by a number of biologically relevant spheres-functional domains in soil. In this paper, the role of soil biota in soil ecosystem processes was assessed, and the relationship between soil biodiversity and ecosystem function was presented. Soil ecosystem responses to global change were also discussed.

The Systems Identification Problem and the Development of Ecosystem Models

Abstract: The construction of large-scale mathematical (simulation) models of an environment confronts the ecologist with a variety of problems. It is the purpose of this paper to analyze one often ignored in the formulation of ecosystem models: the systems identification problem. Systems identification is a field of system theory that can be formally defined as the process of determining coefficients, parameters, and structure of a mathematical model in such a way that it describes a physical process in accordance with