Showing papers on "Ecosystem published in 1971"

Stability and Diversity at Three Trophic Levels in Terrestrial Successional Ecosystems

Abstract: An ecosystem perturbation experiment in which inorganic fertilizer was added to two successional old fields of different ages indicated that stability, expressed as resistance to modification by enrichment, increased during succession only at the primary trophic level. The perturbation was propagated throughout the arthropod herbivores and carnivores. Both herbivores and carnivores were less stable in the older field. In contrast to current ecological theory, greater diversity at a trophic level was accompanied by lower stability at the next higher level.

Biogeography: a study of plants in the ecosphere

Abstract: 1 Introduction Part I: The Biosphere 2 The biosphere 3 Environmental variables 4 Historical biogeography 5 Biomass characteristics 6 Biological productivity 7 The biological cycling 8 Biomass change and soil development Part II: Ecosystems: 9 Tropical and temperate forest ecosystems 10 Boreal ecosystems 11 Grassland ecosystems 12 Desert ecosystems 13 Island ecosystems 14 Mountain ecosystems 15 Aquatic ecosystems Part III: Biotic resources: use and misuse 16 Ecosystems, stability and disturbance 17 Human impact: ecosystem exploitation 18 Human impact: environmental pollution 19 Managed ecosystems 20 The urban ecosystem 21 Conservation

Bacterial populations as components of oceanic ecosystems

Abstract: The production of bacterioplankton in tropical waters is shown to be a major food source for filter feeders. Since this production greatly exceeds autotrophic production by phytoplankton, the external energy source is believed to be soluble organic material transported from temperate latitudes. In the latter environment this material is produced as part of excessive autotrophic production, but its destruction by bacteria is inhibited at low temperature. The organic material is transported by global circulation to warm tropical waters, where it is utilized to form particulate organic aggregates which serve as food for filter feeders.

Mineral Equilibria in Ecosystem Geochemistry

Abstract: In terrestrial ecosystems the composition of runoff water may not reflect chemical equilibrium conditions, but rather chemical flux conditions through an open system. The irreversible flow of chemicals through the boundaries of an ecosystem, as exemplified by chemical weathering, may assume a time—invariant mode (steady—state) which resembles a state of equilibrium in a closed system. See full-text article at JSTOR

The Ecosystem Complex A New Approach in Specifying the Man-Environment Relationship

Abstract: A three-dimensional paradigm is suggested for defining the relationships between an organism and its environment. Called The Ecosystem Complex, its constituents fall into three main classes: 1) Physical factors which are used to define the physical environment include sound, light, area-volume, radiation, inspired gas, atmospheric pressure, force field, air movement, and temperature and relative humidity; 2) Organismic factors which are used to define the organism within the physical environment include age, sex, rhythmicity, psyche, drive, body-type, sensory processes, and genetics; and 3) Reciprocative factors which enable the organism to adapt to the physical environment include diet, clothing, exposure time, social variables, incentive, and activity. Together, these variables and their dynamic interactions must be defined or otherwise specified when determining the effects of the environment on health (physiology), behavior, or affectivity. The potential of the paradigm for use by life-scientists, engineers, planners, and architects is discussed.

Distribution of Radioactive and Stable Zinc in an Experimental Marine Ecosystem

Abstract: The distribution of radioactive and stable Zn in an experimental marine ecosystem is described. We added 1 mCi of 65Zn to 2000 liters of sea water and a mixed community of planktonic and benthic al...