Since the publication of Lowman and Rinker’s Forest Canopies (2^nd edition) in 2004, exciting research has continued in the High Frontier. In this brief overview of canopy ecology, I will touch on a few highlights of recent work which follows up some of the topics addressed in Forest Canopies. The interface between herbivory and nutrient cycling continues to be a particularly rich area for canopy research. Le Mellec and Michalzik (2008) found significant increases in throughfall inputs of total and dissolved organic carbon and nitrogen during an outbreak of the pine lappet in Scots pine.  Madritch et al. (2007) reported that frass inputs from canopy herbivores varied with leaf chemistry among aspen clones and influenced soil respiration. Meehan and Lindroth (2007) have modeled nitrogen flux from frass fall and determined that larval nitrogen flux remained fairly constant even when nitrogen content of their food varied, suggesting that larvae compensated for low quality leaves by consuming more of them. Influences on nutrient fluxes by an invasive herbivore, the hemlock wooly adelgid, included increasing nitrogen concentration in birch litter when subjected to throughfall affected by the HWA (Stadler et al. 2006). As a reminder of the complexity of interactions which ecologists study, Mooney’s 2007 paper in Ecology reported that birds and ant predators reduced the numbers of most herbivorous arthropods, but had opposite effects on aphids. Recent biodiversity studies on canopy organisms include reports on oribatid mite communities of British Columbia by Winchester et al. (2008), camera trap records of small mammals in the Atlantic Forest of Brazil (Oliveira-Santos 2008), and arboreal arthropods found in epiphytes in Maine. Changes in canopy cover were shown to influence the abundance of microarthropods in litter (Kaminski et al. in press) and to mediate interactions between a specialist caterpillar and seedling leaves of a neotropical tree (Norghauer 2007). New sensors providing hyperspatial and hyperspectral resolution have recently been used for biodiversity (Nagendra and Rocchini 2008), canopy nutrient (Chambers et al. 2007) and CO2 flux measurements (Muraoka and Koizumi 2009), the later improving our understanding of global climate change effects.   

Results/Conclusions

Canopy ecology of forests continues to be a productive field of inquiry. Improvements in physical access and remote sensing allow ecologists to increase our knowledge of biodiversity and further our understanding of processes such as nutrient cycling, herbivory, and effects of climate change.