Forest Canopies

Ecology, July, 1996 by Evan H. DeLucia

The book is organized in four parts: I) "Structure and Function of Tree Canopies," II) "Organisms in Tree Canopies," III) "Processes in Tree Canopies," and IV) "Human Impacts on Canopy Research."

The first-part, on structure and function, includes chapters on canopy access, tree architecture, exchange processes (energy and matter), and canopy microclimate. The review of different methods of canopy access is entertaining and encompasses descriptions of the "low tech" methods of hands-on climbing to the more "high tech" aspects of using a canopy crane or ultralight aircraft. This is clearly an endeavor for the courageous, as is evident from the story of a graduate student who took a 120[feet] plunge after forgetting to hook in his climbing gear - he survived but doesn't look quite the same. The sections on exchange processes and microclimate are contemporary and informative. Unfortunately, the chapter on architecture is largely descriptive and devoid of solid functional inferences.

The second and largest section examines canopy organisms from tropical arthropods to lizards, birds, mammals, epiphytes, and hemiepiphytes. These chapters are well referenced and provide a good entrance into the literature. Erwin's chapter on arthropod biodiversity is notable. In an historical overview, he brings to life the urgency and woeful state of our understanding of the biodiversity of canopy arthropods. Many of the organismal chapters are very descriptive - this seems to reflect the embryonic nature of the research on almost all canopy organisms.

The third part examines canopy processes, including chapters on photosynthesis, herbivory, reproductive biology, and nutrient cycling. The photosynthesis chapter provides a good overview. However, given contemporary concerns about the preservation of biodiversity, I was surprised that the issue of species composition and its influence on canopy fluxes was not addressed. The emphasis on sexual systems and population structure in the section on reproductive biology rendered this chapter out of place.

Part four addresses various aspects of human impact on canopy research. Bennett provides an encyclopedic overview of human uses of epiphytes and vines. It is not easily read with its lists of taxa and their uses but provides practical information. For example, one particularly obliging genus, Mandevilla, contains one species that is a source of an aphrodisiac and another species that follows up with a remedy for venereal disease. I would hope they are sympatric. The chapter on collection of canopy plant materials was redundant with other sections on canopy access, and the chapter on tourism seemed irrelevant.

As with many edited volumes there is some redundancy, particularly in reference to canopy access methods, and the frequent naive pleas for standardized methods were distracting. Also, I found the sentiment expressed by the editors and others that the study of forest canopies is a fundamentally new scientific endeavor to be curious, if not misleading. Certainly, forest canopies represent a relatively under-explored location where our contemporary concepts of ecology, evolution, and physiology are at play. It represents a new habitat to understand, but should not be viewed as a unique scientific discipline. The enthusiasm expressed in many of the chapters was contagious and the contributions are, as a whole, well written, referenced, and illustrated. Many of the chapters concluded with a "future research" section which students will find engaging. There is an excitement reading about these explorations tens of meters above the forest floor in the tropics and this volume will provide a solid reference and foundation for those wishing to initiate inquiries in this unexplored habitat.

EVAN H. DELUCIA UNIVERSITY OF ILLINOIS, URBANA - CHAMPAIGN Department of Plant Biology 265 Morrill Hall Urbana, Illinois 61801