The Diversity-Disturbance Relationship Revisited

Open Access
Author:
Ready, Trine
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Katriona Shea, Thesis Supervisor
  • James Harold Marden, Honors Advisor
  • James Harold Marden, Faculty Reader
Keywords:
  • Intermediate Disturbance Hypothesis
Abstract:
The Intermediate Disturbance Hypothesis has been widely accepted in ecology ever since it was first proposed in the 1970s. The IDH states that diversity and disturbance are strongly linked and that the diversity of a system is maximized at an intermediate level of disturbance to form a unimodal peaked relationship. However, diversity-disturbance relationships of a far wider variety of shapes are recorded in the ecology literature. Mackey and Currie (2001) tested the IDH by analyzing the literature from 1985 to 1996 and cataloguing 197 diversity-disturbance relationships by shape. They found that unimodal peaked relationships made up only a small minority of documented relationships. Since Mackey and Currie (2001), the diversity-disturbance literature has expanded greatly. I analyzed the ecological literature from 2008 to 2018, using a protocol similar to that in Mackey and Currie (2001), and catalogued 581 relationships by shape to assess the relative frequency of different diversity-disturbance relationships recorded in more recent publications. As in the earlier work, I found a lack of consistent patterns in diversity-disturbance relationships. Unimodal peaked relationships still did not make up a majority of the relationships seen, comprising only 32.2% of relationships. When the observed relationships were categorized by disturbance and system characteristics, used species evenness as a diversity measure, measured disturbance on a ‘time since last disturbance’ gradient, or were derived from experimental studies, all displayed a significant decrease in the percentage of unimodal peaked relationships when compared to the overall distribution of relationships. Overall, diversity-disturbance relationships can still not be fully described by the Intermediate Disturbance Hypothesis.