Eastern Old‐Growth Forests: Two Books Twenty‐two Years Apart

A review of Andrew Barton, and William Keeton, editors. Ecology and Recovery of Eastern Old-Growth Forests. Island Press, Chicago, Illinois, USA, 2018. When most people pick up a book about eastern old-growth forests, they want to know how many of these wild forests remain, where they are, what makes them unique, how we can preserve the few left, and how we can help some of our forests recover their original, pre-logged, condition. A 1996 book edited by Mary Byrd Davis addressed all of these questions and more. But that book is now more than twenty years old. My review will focus on the similarities and differences between the new Barton and Keeton book and the earlier Davis book. This seems appropriate since both books were published by Island Press and the newer book's cover seems to purposefully resemble Davis's book, and indeed both spines proclaim “EASTERN OLD-GROWTH FORESTS” in caps. Reaching for one or the other on the shelf requires a close look to tell them apart. Although there is a nod to biodiversity, the emphasis in this volume leans instead toward natural disturbance dynamics, threats to the forest, and silviculture. The disturbance chapter by D'Amato et al. does an excellent job at presenting the newest research in disturbance dynamics. The chapter includes discussions of wind, specific insects, pathogens, wildfires, ice storms, and drought and then ranks all the various disturbances by severity and scale. Much of this chapter, however, veers into a discussion of ecological silviculture. Most ecologists, myself included, are in favor of more sensitive forest management that mimics natural disturbances and promotes the structures found in old-growth forests: such as tip-up mounds, increased coarse woody debris, standing dead trees, and larger living trees; but the old-growth forests we study, and try to preserve, exist because they have escaped both silviculture and severe natural disturbance. By definition (pg. 2), old-growth forests contain old trees and are relatively undisturbed by people. Silviculture, no matter how sensitive, is a human-inflicted disturbance. There is a very good biodiversity chapter by Gregory McGee, but it primarily addresses vascular plants, mosses, lichens, fungi, and small invertebrates such as mites, springtails, and spiders. In contrast, Davis's 1996 book also had chapters on vertebrate relationships with old-growth forests including salamanders, birds, carnivores, and even humans. With the exception of a few paragraphs about salamanders, the new book does not address the relationship of vertebrates with old-growth forests. The chapter on forest–stream interaction in eastern old-growth forests by Dana Warren et al. is a useful addition that was not covered in Davis's book. As Warren's team notes on page 159, “streams bordered by old-growth forests are profoundly different from those surrounded by younger forests.” The importance of large dead wood in streams to fish and macroinvertebrates is discussed. Also discussed are the forest influences of stream light regimes and nutrient cycling on stream ecology. Those interested in stream restoration in wooded habitats should pay particular attention to this chapter. Similar to the Davis book, there are chapters describing specific old-growth forest communities such as bottomland hardwood forests, pine woodlands, Southern Appalachian mountain forests, hardwood–hemlock forests, and boreal forests. These chapters will be of interest to anyone who works in those particular ecosystems. The pine chapter by Robert Peet et al. is particularly well done. They have included a map and a table that organizes the remaining old-growth southeastern pine savannas into useful categories. The boreal forest chapter by Kneeshaw et al. has an interesting discussion of planning for natural disturbances by managing on a landscape scale instead of a single forest scale. But, as they remark on pages 146–147, “such foresight and long-term large-scale planning is an aspirational concept that remains a long way from being made operational.” Most troubling to me was the chapter on silviculture by Keeton et al. On page 238, they pose the interesting question: “Is it better to let old growth recover passively or could silvicultural methods be used to restore or increase the representation of old-growth characteristics in secondary forests?” Instead of presenting data to answer that question, the idea of passive recovery is waved away with a pen stroke. They write: “In the Anthropocene, the idea of just letting nature take its course no longer seems to be an adequate strategy.” Without further proof, I am not convinced of this. A paragraph later they write: “Even if passive management could restore healthy old-growth forests, the process in the existing second-growth would often involve a delay of another 60–150 years.” While their arguments to use active management to increase structural complexity in second-growth forests are persuasive and could lead to increased habitat types and increased biodiversity in the short term, time is integral to the development of an old-growth forest. Thinking that putting more woody debris on the forest floor, and scarifying and pushing over some trees, will create an old-growth forest is like thinking you can make a teenager an elderly person by dying their hair gray. Calling this sort of management “old-growth silviculture” is somewhat misleading. “Old-growth-like silviculture” or “silviculture for old-growth characteristics” would be less confusing. Also, when discussing the benefits or drawbacks of active management for creating old-growth-like characteristics in a specific forest, one should be very clear if the management is for a forest that will continue to have wood fiber taken out of it (a “working forest”), or if it is a preserved forest where natural forces will be allowed to prevail. Silviculture, even as sensitive and well-intentioned as the type described here, may not be appropriate for the latter. These distinctions are not well developed here, and the emphasis seems to be toward managing for “multiple benefits” with talk of rotation periods or entry times. This well-researched and well-written chapter would be an excellent addition to a silviculture book, but it felt out of place in a volume titled Ecology and Recovery of Eastern Old-Growth Forests. The chapter on silviculture would be stronger if it also discussed the drawbacks to active management. Do we really need to mimic natural disturbance processes when they are still at work? Does the introduction of humans with chain saws (for creating snags and coarse woody debris) and heavy equipment (for tipping over trees) have any negative consequences for other forest organisms (such as herbaceous plants, snails, and turtles)? The introduction of nonnative invasive plants is a huge risk associated with any sort of active management these days. A chapter by John Gunn and David Orwig spells out the impact of this growing threat, along with all the rest of the invaders from the emerald ash borer to beech bark disease. In the past twenty years, climate change has become an important factor in forest disturbance and in the value of carbon sequestration by old-growth forests. Discussions of climate change are to be found in many of these chapters. A very useful chapter by Keeton discusses our current understanding of carbon dynamics in forests as they age and change. Again, however, the discussion moves toward silviculture. Silviculture for old-growth characteristics is encouraged for working forests as a way to increase carbon stocking and potentially reap the financial rewards of the carbon market. The Wildlands and Woodlands vision Foster (2017) promoted by Harvard Forest for the New England landscape calls for 10% of the forests to be treated as wildlands to protect biodiversity and wilderness. Since we are nowhere near that percentage at present, we need to have serious discussions about how we can begin to let formerly logged forests become wild once again. It would have been nice to see that discussion in this new book. As biologist Victor Scheffer (1973) says, “The wisdom, goodness, and greatness of Man will be measured not wholly by technical power over the wild things of Earth but also by his moral strength in letting them be.” Although this book is an important reference for those studying eastern old-growth forests, it will not replace Davis's iconic 1996 volume.