The role of disturbance and resource availability in structuring plant communities

Disturbances alter competitive hierarchies by reducing populations and altering resource regimes. The interaction between disturbance and resource availability may strongly influence the structure of plant communities, as observed in the recolonization of seagrass beds in outer Florida Bay that were denuded by sea-urchin overgrazing. There is no consensus concerning the interaction between disturbance and resource availability on competition intensity (CI). On the other hand, species diversity is dependent on both factors. Peaks in species diversity have been observed to occur when both resource availability and disturbance intensity are high, thus implying that CI is low. Based on this supposition of previous models, I presented the resource-disturbance hypothesis as a graphical model to make predictions of CI as a function of both disturbance intensity and the availability of a limiting resource. The predictions of this model were tested in two experiments within a seagrass community in south Florida, in which transplants of Halodule wrightii were placed into near-monocultures of Syringodium filiforme in a full-factorial array. In the first experiment, two measures of relative CI were calculated based on the changes in the short-shoot number (SS) and of rhizome length (RHL) on the transplants. Both light and disturbance were identified as important factors, though the interaction between light * disturbance was not significant. Relative CISS ranged between 0.2 and 1.0 for the high light and high disturbance treatments and the relative CIRHL < 0 for the same treatments, though results were not significantly different due to high variability and low sample size. These results, including a contour schematic using six data points from the different treatment combinations, preliminarily suggests that the resource-disturbance hypothesis may be used may be used as a next step in developing our understanding of the mechanisms involved in structuring plant communities. Furthermore, the focus of the model is on the outcome of CI, which may be a useful predictor of changes in species diversity. Further study is needed to confirm the results of this study and validate the usefulness of this model in other systems. ^

The Nevada Gaming Debt Collection Experience

In the discussion - The Nevada Gaming Debt Collection Experience - by Larry D. Strate, Assistant Professor, College of Business and Economics at the University of Nevada, Las Vegas, Assistant Professor Strate initially outlines the article by saying: “Even though Nevada has had over a century of legalized gaming experience, the evolution of gaming debt collection has been a recent phenomenon. The author traces that history and discusses implications of the current law.” The discussion opens with a comparison between the gaming industries of New Jersey/Atlantic City, and Las Vegas, Nevada. This contrast serves to point out the disparities in debt handling between the two. “There are major differences in the development of legalized gaming for both Nevada and Atlantic City. Nevada has had over a century of legalized gambling; Atlantic City, New Jersey, has completed a decade of its operation,” Strate informs you. “Nevada's gaming industry has been its primary economic base for many years; Atlantic City's entry into gaming served as a possible solution to a social problem. Nevada's processes of legalized gaming, credit play, and the collection of gaming debts were developed over a period of 125 years; Atlantic City's new industry began with gaming, gaming credit, and gaming debt collection simultaneously in 1976 [via the New Jersey Casino Control Act] .” The irony here is that Atlantic City, being the younger venue, had or has a better system for handling debt collection than do the historic and traditional Las Vegas properties. Many of these properties were duplicated in New Jersey, so the dichotomy existed whereby New Jersey casinos could recoup debt while their Nevada counterparts could not. “It would seem logical that a "territory" which permitted gambling in the early 1800’s would have allowed the Nevada industry to collect its debts as any other legal enterprise. But it did not,” Strate says. Of course, this situation could not be allowed to continue and Strate outlines the evolution. New Jersey tactfully benefitted from Nevada’s experience. “The fundamental change in gaming debt collection came through the legislature as the judicial decisions had declared gaming debts uncollectable by either a patron or a casino,” Strate informs you. “Nevada enacted its gaming debt collection act in 1983, six years after New Jersey,” Strate points out. One of the most noteworthy paragraphs in the entire article is this: “The fundamental change in 1983, and probably the most significant change in the history of gaming in Nevada since the enactment of the Open Gaming Law of 1931, was to allow non-restricted gaming licensees* to recover gaming debts evidenced by a credit instrument. The new law incorporated previously litigated terms with a new one, credit instrument.” The term is legally definable and gives Nevada courts an avenue of due process.