Frequent small animal disturbances maintain grassland diversity as a fine-grained mosaic

Evidence

A different perspective emerges from the work of Piatt (1975), Giesel (1976), and Wiens (1976). These authors, in conjunction with Levin and Paine (1974), suggest that patchy environments can be essential in maintaining the biological diversity characteristic of certain communities. An extension of this view leads to the hypothesis that the populations of animals in the arid grasslands could have produced annually a sufficient disturbance habitat to assure the maintenance of certain species requiring openings for seedling establishment. In Piatt’s study, the disturbance agents were populations of badgers and pocket gophers. In the patchy environments reported on by Baxter and Hole (1967), the disturbance agents were several grassland species of mound-building ants. In both examples, an alternate view of the grassland community emerges, one in which a large number of small disturbances produces a dynamic mosaic of small, short-lived patches utilized by opportunistic species. A type of secondary succession may take place in the larger disturbances, or the patches may simply disappear by edge closure. Thus, the prairie, as sampled at the relatively coarse level of most community measurements, may need to be examined as a composite of both pioneer and K-selected or climax species, not necessarily mixed in a single community but as a mosaic of two or more communities (or age-states) in a dynamic, fine-textured mosaic. — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 499

Categorization

• XREF: Generalizes the patch-dynamics thesis beyond forests (chs 4-5): badgers, gophers, and ants stand in for treefall gaps as diversity-sustaining disturbance agents — a key bridge for the reader’s own synthesis. — connects to: Shrubland diversity arises from varied disturbance rather than a single optimum — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 672; Unrelated sessile communities obey the same disturbance-diversity rule — Robin Wall Kimmerer, Gathering Moss: A Natural and Cultural…, 300; Localized disturbances turn sessile assemblages into a patch mosaic — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 681 (+6 more)
• ADDENDUM: Little animals as disturbance ‘engineers’ could feed the trees-as-infrastructure article’s logic by supplying a complementary story: fauna as small-scale disturbance infrastructure in grass systems.

Broader Connections

• Localized disturbances turn sessile assemblages into a patch mosaic #expands (0.82) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 681
• Shrubland diversity arises from varied disturbance rather than a single optimum #expands (0.78) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 672
• Unrelated sessile communities obey the same disturbance-diversity rule #expands (0.75) — Robin Wall Kimmerer, Gathering Moss, 300
• Repeat disturbances near old gaps are common and favor growth-suppression alternating species #expands (0.74) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 230
• The same disturbance-diversity dynamics governing forest trees also structure moss communities on logs #corroborates (0.72) — Robin Wall Kimmerer, Gathering Moss, 371
• Symmetrical competition makes disturbance-diversity peaks unpredictable #corroborates (0.70) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1006