Forest canopy studies as an emerging field of science

Abstract

Scientific fields go through stages of maturity, as do plants, people, and societies. A scientific field in its infancy is typified by descriptive studies by individual scientists who identify phenomena and document patterns. As a field matures, investigations involve multiple researchers who address process-oriented questions to explain the observed patterns. A sign of maturity for a field is when its scientists can validate predictive models and relate findings to those of other fields (Lodahl and Gordon 1972). Studies of the forest canopy—“the aggregate of all crowns in a stand of vegetation” (Parker 1995)—constitute a scientific field that has passed through some of these stages with remarkable speed, but has not yet attained all of the attributes of full maturity. Thirty years ago, the canopy was considered an insignificant part of the forest ecosystems with little scientific attention beyond a few taxonomists specializing in arboreal biota. The development of three technological innovations coincided with the subsequent rapid growth of canopy studies: (1) mountainclimbing methods, fogging techniques, and construction equipment to facilitate access (Erwin 1982; Moffett and Lowman 1995); (2) easy-to-use equipment for making whole canopy measurements of material and energy exchanges with the atmosphere (Baldocchi et al. 1988), and (3) methods to measure the structure of whole canopies (e.g., LIDAR, Gonzalez et al. 2010). Canopy studies relate to the field of forest ecology, and related fields: e.g., atmospheric sciences, entomology, vertebrate biology, and soil science. A growing literature and textbooks now document our expanding knowledge of the composition, structure, and function of canopy biota, and their responses to changes in environmental conditions (Lowman and Rinker 2004; Lowman and Moffett 1993; Lowman and Nadkarni 1995; Mulkey et al. 1996), including general review papers (Lowman 2009; Parker and Brown 2000) and reviews of specific topics, e.g., epiphytes (Benzing 1990), canopy insects (Basset et al. 2003), and tree physiology (Ryan 2002). Canopy symposia are convened at scientific meetings, and international canopy conferences are held every 4 years. Formal networks exist for communication among researchers. Effects of human activities on canopy biota have been documented at the global level, particularly for climate change and forest fragmentation (Nadkarni and Solano 2002; Ozanne et al. 2003). Canopy research has extended into the policy arena, on issues such as Reducing Emissions from Deforestation and Forest Degradation. This work has received increasing public interest, manifested in popular publications (e.g., Moffett 1993), and numerous media pieces. However, certain aspects to support a vigorous field of science have not yet been attained. A canopy resources website (“the Big Canopy Database”) was initiated in 1999, but support has been based on short-term funding (McIntosh et al. 2007). An attempt to create a journal Handling Editor: Erwin Dreyer