Resource competition

For Polygonella myriophylla, a prostrate woody perennial that has numerous primary and secondary branches that form dense mats, field observations of root mass distribution rule out belowground competition as a significant factor in the 

The chemistry of five scrub perennials have now been investigated (Macias et al. 1989 Menelaou et al. 1993 Tanrisever et al. 1987, 1988 Weidenhamer 1987 Weidenhamer et al. 1993, 1994 Williamson et al. 1989). For P. myriophylla, the major secondary components of the plant and leaf wash were identified, with the assumption that these compounds or their derivatives were most likely to 

Two species produce phytotoxic monoterpenes Conradina canescens contains a mixture of monoterpenes, including 1,8-cineole, camphor, and bomeol (Williamson et al. 1989). Calamintha ashei contains a mixture of menthofuran monoterpenes (Tanrisever et al. 1988 Macias et al. 1989 Weidenhamer et al. 1994). Both species are mints, and presumably contain the terpenes in glandular tri-chomes on the leaf surface. Studies of the solubility of these compounds showed that their aqueous solubility is far in excess of their toxicity (Weidenhamer et al. 1993), which is necessary if these compounds are to be transported to the soil in aqueous solution by precipitation throughfall. 

For three species, environmental transformation of plant natural products into more toxic substances seems to be significant. Leaf washes of Ceratiola ericoides contain the inactive dihydrochalcone ceratiolin, which in aqueous solution degrades to phytotoxic hydrocinnamic acid on exposure to light (Tanrisever et al. 1987 Fischer et al. 1994). Leaf washes of Chrysoma pauciflosculosa contain the diterpene 17-hydroxygrindelic acid as a major component. This compound is readily oxidized to 17-oxogrindelic acid, which is more toxic (Menelaou et al. 

Quantitation of allelochemical release rates has been attempted for one species, Calamintha ashei. Concentrations of menthofuran monoterpenes were measured in leaf soaks and washes collected biweekly for 1 year (Weidenhamer et al. 

---

Tilman, D. (1982). Resource Competition and Community Structure. Princeton Princeton University Press. 

Sterner RW (1989) Resource competition during seasonal succession toward dominance by cyanobacteria. Ecology 70 229-245... 

Blooming of dinoflagellates is a complex affair, contemplated in the paradox of plankton . That is, at the equilibrium, resource competition models suggest that the number of coexisting species cannot exceed the number of limiting resources. In contrast, within nature, more species can coexist. A rationalization of these phenomena, possibly solving the paradox, may be found in species oscillations and chaos, without the need of advocating external causes (Huisman 1999). 

Additional benefits derived from cover cropping include weed and disease suppression. Approaches for managing weeds are discussed below however, the main mechanism of weed suppression by cover crops appears to be resource competition, rather than factors such as allelopathy (Bond and Grundy 2001). The different occurrence of the fungal pathogen... 

Inderjit and del Moral, R. Is separating resource competition from allelopathy realistic Bot Rev 1997 63 221-230. 

Weidenhamer J.D. Distinguishing resource competition and chemical interference overcoming the methodological impasse. Agron J 1996 88 866—875. 

Tilman, D. (1977) Resource competition between plankton algae an experimental and theoretical approach. Ecology 58, 338-348. 

Brzezinski, M. (1992). CeU-cycle effects on the kinetics of silicic acid uptake and resource competition among diatoms. /. Plankton Res. 14, 1511—1539. 

Gl] J. P. Grover (1991), Resource competition in a variable environment Phytoplankton growing according to the variable-internal-stores model, American Naturalist 138 811-35. 

The impacts of toxicants upon the structure of communities has been investigated using the resource competition models of Ulman. Species diversity may be decreased or increased and a rationale for studying indirect effects emerges. 

Resource Competition as a Model of the Direct and Indirect Effects of Pollutants... 

Resource competition as modeled by David Tilman and adopted for toxicological purposes by Landis may assist in putting into a theoretical framework the varied effects of toxicants on biological systems. Detailed derivations and proof can be found in Ulman s excellent monograph. This brief review is to demonstrate the utility of resource competition to the prediction, or at least explanation, of community level impacts. 

The basis for the description of resource competition is the differential uptake and utilization of resources by species. The use of the resource, whether it is space, nutrients, solar radiation, or prey species can be described... 

The basic assumptions made in order to model the impacts of toxicants on the competitive interactions discussed above are (1) the toxicant affects the metabolic pathways used in the consumption of a resource and (2) this alteration of the metabolism affects the growth rate vs. resource curve. In terms of resource competition, the consumption vector is changed, and the shape and placement of the ZNGI is altered. In the following discussions the implications of these changes on examples using essential resources are depicted. 

In the first example, the initial conditions are the same as used to illustrate the two-species resource competition model with essential resources (Figure 11.7). The toxicant alters the ability of species B to use resource 1. The slope of CB increases and the ZNGI and the CB shift the equilibrium point and... 

Impacts of toxicants upon the components of resource competition. The relationships among the factors incorporated into resource competition models can be affected in several ways by a toxicant. Only the density independent factors governing mortality escape. 

The use of resource competition models also leads to a classification or a flow diagram describing the potential impacts of toxicants upon competitive interactions (Figure 11.12). The toxicant can directly or indirectly alter every aspect of the competitive interaction except the nonspecific or density-independent mortality. 

Landis, W.G. 1986. Resource competition modeling of the impacts of xenobiotics on biological communities. In Aquatic Toxicology and Environmental Fate, Vol. 9, ASTM 921. T.M. Poston and R. Purdy, Eds. American Society for Testing and Materials, Philadelphia, PA, pp. 55-72. 

What is resource competition What is a resource consumption vector What is a ZNGI ... 

It is also important to consider any possible deleterious effects that resveratrol and its metabolites may have on plants. Production of defensive stilbenes in plants results in resource competition between parallel biosynthetic pathways. For example, one group of metabolites that may be severely impacted by this competition is the chalcones and their metabolites that play a variety of important roles in plants. These compounds share a pool of basic precursors with the stilbenoids [134,135]. Alterations in stilbenoid production could have far reaching effects on the health of the plant. The severity of this problem has been highlighted by Fischer and colleagues [136] who reported that overexpression of a stilbene synthase gene in transgenic tobacco and petunia plants resulted male in sterility. 

Negative effects caused by removal of resources COMPETITION... 

Wickens, C. D., Sandry, D. L., and Vidulich, M. (1983), Compatibility and Resource Competition Between Modalities of Input, Central Processing, and Output, Human Factors, Vol. 25, pp. 227-248. 

Ciros-Perez, J., Carmona M.J., Serra, M. (2001). Resource competition between sympatric sibling rotifer species. Limnology and Oceanography 46, 1511-1523. 

Panidielli, L and Gnansounou, E. (2008) GIS-based approach for defining bioenergy facilities location a case study in Northern Spain based on marginal delivery and resources competition between facilities. Biomass Bioenergy, 32, 289-300. 

Our data best support the predator avoidance hypothesis, because this hypothesis cannot be rejected, and the other hypotheses can be devalued or rejected based on the available evidence. The interspecific competitor avoidance hypothesis, a potential explanation in the trials involving spotted salamanders, is rejected because the large size difference between the salamander species would result in very little resource competition (Burton Likens, 1975), and the behavior of spotted salamanders toward red-backed salamanders resembles predatory attack and includes the consumption of red-backed salamanders (Ducey, et al., 1994). 

Improved efficiency, better recycling and the introduction of innovative processes and materials can reduce resource competition. 

The justification for the difference in standards of proof is, however, not entirely clear. It may have been a response to b. and c. above and/or may have occurred because the concept of plant-plant allelopathic interactions challenged the long held paradigm of resource competition. In addition, organic substances involved in plant-plant allelopathic interactions can be exceedingly ephemeral, i.e., are readily metabolized, leached, volatilized, and/or bound (sorbed). Interestingly enough. 

---