The Strategy of Mineral Cycling
01 Nov 1970-Annual Review of Ecology, Evolution, and Systematics (Annual Reviews 4139 El Camino Way, P.O. Box 10139, Palo Alto, CA 94303-0139, USA)-Vol. 1, Iss: 1, pp 171-190
TL;DR: Investigations of essential elements are now in a transition period between Liebig-dominated studies, often of single ele ments, and ecosystem analysis, and this review consists of a selective review of recent accomplishments and speculation on some of the difficul ties to be overcome as the authors complete the transition.
Abstract: Ecologists' attitudes have been so shaped by Justus Liebig (36) that most studies of biologically essential elements concern the limits they place on the productivity of an ecosystem or population. We are coming to realize that it is probably less common for a single element to impose a clear-cut limit on an ecosystem than for more complex interactions to occur. Ed mondson (74) has given some examples of this in aquatic ecosystems. Real ization of the importance of interactions has come with the development of a systems viewpoint in ecology. This viewpoint gives new impetus to the study of mineral cycling. As manifestations of the function of natural sys tems, cycles of essential elements are convenient points of entry into the analysis of ecosystems. The flux of materials is essential to the continuity and stability of any living system. Moreover, flux is often a good indicator of metabolic activity, and it follows the pathways of energy through food webs. For these reasons studies of the cycles of essential elements are a useful strategy for ecosystem analysis. The systems viewpoint, or some aspect of it, can frequently be seen in ecological works going back many years, but only recently have ecologists begun to use systems analysis in the formal sense. There has been a rapid rise in mathematical modeling of ecosystems, which sometimes includes computer simulation and uses the flux of energy or a single element as the index of function (14, 51, 75, 87). A number of studies present compart mental models of ecosystems, with known standing stocks and known flux between compartments (5-7, 10, 64, 78). In most cases these are progress reports along the way to more complete analysis. There also have been use ful analyses of artificially assembled and manipulated microcosms (58) and of hypothetical systems (86). Investigations of essential elements are now in a transition period between Liebig-dominated studies, often of single ele ments, and ecosystem analysis. This review consists of a selective. consider ation of recent accomplishments and of speculation on some of the difficul ties to be overcome as we complete the transition. The essential nature of an element in an ecosystem is a direct result of its necessary role in the structure and function of the cells that make up
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TL;DR: This paper reviews studies that investigate the effects of plants on metals in wetlands and suggests that metals in litter are available to deposit feeders and, thus, can enter estuarine food webs.
905 citations
Cites background from "The Strategy of Mineral Cycling"
...Research on nutrients such as nitrogen (White and Howes, 1994) and phosphorus (Pomeroy, 1970) have demonstrated the importance of plant productivity, physiology and allocation patterns to salt marsh element cycles....
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TL;DR: Carbon-to-element ratios in decomposing litter varied between species and elevation at different times of the year, but element:P ratios were much more uniform.
Abstract: Rates of weight loss and nutrient release (N, P, S, K, Mn, Ca, Zn, Fe, Mn, Cu. Na) were measured in decomposing leaf and branch tissue from yellow birch, sugar maple, and beech, and in branch tissue from red spruce and balsam fir. Neither leaf nor branch decomposition differed significantly over an elevational range of 220 m. Decomposition rates for leaves varied with yellow birch > sugar maple > beech. The decomposition rate for hardwood branches was greater than that for conifer branches, but differences between hardwoods were not significant. Maximum decomposition rates occurred during the summer for both branch and leaf tissue. The rate of nutrient release from decomposing branch and leaf litter appears to be correlated with nutrient concentration in current litter fall, precipitation, and leaf wash. The concentration and absolute weight of N, S, and P in the leaf litter of all species increased with time. The amount of the increase as well as the initiation of nutrient release was influenced by C:element ratios in the leaf tissue. These studies also indicate that P levels can influence the mineralization or immobilization of other important nutrients. Carbon-to-element ratios in decomposing litter varied between species and elevation at different times of the year, but element:P ratios were much more uniform. In branch tissue the physical loss of N- and P-rich bark and buds offset any increase in concentration that would have occurred through decomposition. Potassium and magnesium were rapidly released from the litter by leaching. Similar minimum concentrations in leaf tissue indicate that critical C:element ratios also exist for these elements. Calcium release was similar to dry weight loss, indicating that it is a structural component primarily released by decomposition. Maximum nutrient release from current litter occurred in the autumn and summer. It was not correlated with the nutrient output from the ecosystem which occurred primarily
592 citations
TL;DR: Although outbreaks (either local or extensive) do reduce plant production temporarily, they commonly occur in individual plants or in whole forest systems that are not particularly productive-that is, those which are under stress resulting from inadequate or excessive moisture, nutrient deficiencies, or pollution, or are senescent, having already passed their peak efficiencies in biomass production.
Abstract: Phytophagous insects are common, ubiquitous elements of most terrestrial ecosystems. Occasionally some species become so abundant that they threaten the stability or output of systems having high ecological, esthetic, or economic value. Forest ecosystems, in particular, support myriads of phytophagous insects, but only few cause dramatic defoliations and widespread destruction of trees. These are termed outbreak species. Four such species currently are stirring public concern in North America: the Douglas fir tussock moth, the gypsy moth, the eastern spruce budworm, and the southern pine bark beetle. Normal insect grazing (from 5 to 30 percent of annual foliage crops) usually does not impair annual plant (primary) production. In fact, it may accelerate growth. Although outbreaks (either local or extensive) do reduce plant production temporarily, they commonly occur in individual plants or in whole forest systems that are not particularly productive-that is, those which are under stress resulting from inadequate or excessive moisture, nutrient deficiencies, or pollution, or are senescent, having already passed their peak efficiencies in biomass production. Moreover, after an outbreak has subsided, there is evidence that the residual vegetation is more productive than the vegetation that was growing immediately before the outbreak. For almost a century, research on phytophagous insects has focused primarily on aspects of their population biology and dynamics and their short-term impact on host plant growth and survival. Only recently has attention been directed at understanding and elucidating their long-term interactions with such fundamental ecosystem processes as primary production and
569 citations
TL;DR: The purpose of this paper is to examine the relative contribution from allochth onous and autochthonous sources of lotic systems in different vegetational regimes (biomes) or arising along a single river system from its source to the sea.
Abstract: where the import of organic matter from outside the system is the predominant feature. Little has been done to test the hypotheses derived from these systems against information obtained from other lotic systems in different vegetational regimes (biomes) or arising along a single river system from its source to the sea. The purpose of this paper is to examine the relative contribution from allochthonous and autochthonous sources of
548 citations
Cites result from "The Strategy of Mineral Cycling"
...This situation is similar to that found for temperate-zone Spartina saltmarshes (Pomeroy 1970)....
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01 Jan 1981
TL;DR: In this article, a strong linear correlation between the organic matter produced in the overlying water and the amount of organic matter consumed on the bottom in almost all of the coastal environments for which annual data are available.
Abstract: Our views of remineralization and nutrient cycling in coastal marine ecosystems have changed considerably over the last 30 years. The major trend has been an increasing appreciation for the complexity of processes involved, including some marked changes in our assessment of the importance of bacteria with respect to smaller animals and in our perception of the association between bacteria and particulate matter in the sea. Among the more recent developments in this area is a growing awareness of the importance of the coupling between benthic and pelagic communities in coastal waters. There appears to be a strong linear correlation between the organic matter produced in the overlying water and the amount of organic matter consumed on the bottom in almost all of the coastal environments for which annual data are available. The large amount of organic matter consumed by the benthos (perhaps 25–50 percent of that produced) is associated with a large flux of inorganic nutrients from the sediments to the overlying water. The stoichiometry of net benthic nutrient regeneration differs from that of pelagic regeneration, however, and simple Redfield type models probably cannot be applied. The amount of fixed inorganic nitrogen returned to the water across the sediment-water interface appears to be about half of that expected on the basis of the flux of phosphorus. This behavior, along with the fact that an appreciable amount of organic matter in coastal waters gets remineralized on the bottom, contributes to the low N/P ratio that is characteristic of these areas and may be responsible for the observation that nitrogen is commonly the nutrient most limiting for primary production. Recent direct measurements of the flux of dissolved N2 across the sediment-water interface indicate that denitrification is probably responsible for the loss of fixed nitrogen during decomposition in the sediments. If this is a widespread phenomenon, estuaries, bays, and other coastal waters may be major sinks in the marine nitrogen cycle and important terms in the global nitrogen budget. However, the fact that eutrophication appears to be an increasing problem in many estuaries is dramatic warning that anthropogenic nutrient inputs can overwhelm the recycling and remineralization processes in coastal waters.
545 citations
References
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Proceedings Article•
01 Jan 1963
4,497 citations
Journal Article•
3,481 citations
TL;DR: The role of zooplankton in regenerating nitrogen as ammonia in the Sargasso Sea is examined theoretically in this article, showing that only about 10% of the daily ammonia uptake by phytoplanton living in the upper 100 m.
Abstract: The use of 15N-labeled compounds to obtain specific uptake rates for the various nitrogen sources available to the phytoplankton makes it possible to separate the fractions of primary productivity corresponding to new and regenerated nitrogen in the euphotic zone of the ocean. Measurements of nitrate uptake as a fraction of ammonia plus nitrate uptake have been obtained from the northwest Atlantic and the northeast Pacific oceans. Mean values range from 8.3 to 39.5%, the former being characteristic of subtropical regions and the latter of northern temperate regions or coastal and inland waters.
Nitrogen fixation is also a source of new nitrogen. Rates of nitrogen fixation are found to be as high or higher than nitrate uptake, in some cases suggesting an important role for nitrogen-fixing phytoplankton.
The role of zooplankton in regenerating nitrogen as ammonia in the Sargasso Sea is examined theoretically. Probably only about 10% of the daily ammonia uptake by phytoplankton is contributed by the zooplankton living in the upper 100 m.
2,655 citations