Vernal
PoolsNatural
History and Conservation
In March 2000, I attended the “Conference on Vernal Pools of New England: Conservation, Ecology, Research” at the University of Rhode Island in Kingston. The two things that most stood out in my mind were that 400 people showed up for the two-day conference and Betsy Colburn’s keynote address, “Conserving vernal pool wildlife: physical factors, biological questions, and policy concerns.” Here was a scientist discussing vernal pools on an ecosystem scale, not just as breeding grounds for mole salamanders (Ambystoma spp.) and fairy shrimp (Eubranchipus spp.).
As soon as I learned that Colburn had published Vernal Pools Natural History and Conservation in October 2004, I read it immediately. I was impressed with the depth and scope of this expansive book about the ecology and conservation of vernal pools of the glaciated Northeast -- and the flora and fauna within them. Conservation biologists, environmental educators, naturalists, and just-plain aficionados of vernal pools will find Vernal Pools informative and valuable.
In her book, as in her talk at the vernal pool conference, Colburn focuses on vernal pools as whole ecosystems – an approach that is long overdue. Chapter 1 defines the vernal pools of the glaciated northeast according to five general, but succinct, criteria that Colburn describes as follows:
· “Woodland context: vernal pools occur in or next to forests or other wooded areas.
· “Isolation: vernal pools lie in confined basins with no continuously flowing inlet or outlet, and they have no continuous surface-water connection with permanently flooded water bodies.
· “ Size: vernal pools are small and shallow.
· “Hydrology: vernal pools fill seasonally, attaining their maximum water levels and volumes in the spring; they dry up annually or every few years – standing water either disappears completely, or water levels drop substantially during the summer… and they contain water for a minimum of two months in most years.
· “Biological community: vernal pools lack established fish populations, and they provide habitat for animals that are adapted to seasonal drawdown and require the absence of fish predation for successful reproduction.”
The rest of the book expands on this definition, providing essential biotic and abiotic characteristics and natural history of vernal pools, and does so with a sense of respect and wonder for these small, unique wetlands.
Coburn breaks new ground in Vernal Pools with her proposed hydrological classification of vernal pools (Chapter 2 Hydrology). She clearly states that hers is a working model that requires further studies and testing. In my limited experience classifying and teaching about vernal pools, it makes sense. Colburn divides vernal pools into 5 classes: short-cycle, spring-filling pools; long-cycle spring-filling pools; short-cycle, fall-filling pools; long-cycle, fall-filling pools; and semi-permanent pools.
Salamanders are to vernal pools what the panda was initially to the World Wildlife Fund – the species that appeals to people’s emotions and curiosity. Colburn’s amphibian chapter (11) is first rate. Chapter 11 and Chapter 14, “Protecting Vernal Pools,” emphasize the importance of the surrounding wooded uplands as well as vernal pool complexes to the successful breeding of these animals. Colburn bluntly presents the argument that we need to look at – and protect -- vernal pools in a new way: not simply as isolated wetland communities but both as part of a meta-complex of other vernal pools and as an entire wetland/woodland landscape. Lest those of us in Massachusetts feel smug about our 100-foot buffer zone to “protect” vernal pools, Colburn reiterates that, as adults, many species of salamanders and frogs have upland home ranges much farther than 100 feet away from their natal vernal pools.
One of the most astounding facts that Colburn reveals about vernal pools and seasonal ponds is their high biodiversity on a landscape or regional level. Colburn notes, “more than 550 species of multicellular animals have been reported from northeastern vernal pools. If animals that have been identified only to the family or generic level are included, the number exceeds 700.” Her appendix, an annotated list of the fauna of vernal pools and seasonal pools, runs 64 pages!
Chapters 4-12 provide overviews of the life histories of many common organisms found in vernal pools, from “Bacteria, Protists, Algae and Fungi”(Chapter 4) to “Reptiles, Birds, and Mammals” (Chapter 12). And Chapter 13 “Energy Flow, Seasonal Cycles, and Variations in Community Composition” pulls together the dynamics of energy flow and trophic structure in vernal pools. Environmental educators will find this chapter a useful teaching tool, particularly Figure 39, which depicts the general food web in vernal pools.
Finally, Colburn offers a list of questions at the end of each chapter which in her words, “it is hoped that the brief summaries of research questions provided here will stimulate interest among academic and governmental researchers, as well as naturalists, classroom teachers, and others, and will serve as an impetus for funding to support additional studies on vernal pools.”
The strength of Vernal Pools lies in its
ecological synthesis of the natural history of vernal pools and their
inhabitants, and its message of conservation.
It is the first comprehensive book about vernal pools that I have
read. However, it is not a
field guide. Complementing
Vernal Pools are two excellent field guides: A Field Guide to
the Animals of Vernal Pools by Leo Kenney and Matthew Burne, 2001,
available through the Massachusetts Natural Heritage and Endangered
Species Program; and A Guide to Common Freshwater Invertebrates of
North America by J. Reese Voshell, Jr., 2002, also published by
McDonald & Woodward.
The views and opinions expressed in all articles that appear in "Conservation Perspectives" are those of the authors and do not necessarily reflect those of NESCB.