When many people look at a forest they see only the trees. This is understandable, as trees are substantially larger than any other organism in the forest. Yet despite their physical dominance, overstory trees generally are not the most species-rich, nor numerically abundant, taxonomic group in a forest. Richness and population sizes of many other organisms, especially herbs, invertebrates, and microbes, may be several orders of magnitude greater than overstory trees.

The ‘other taxa’ of forest ecosystems may outnumber trees, but in many ways the overstory has a profound influence on their existence. In this context, the overstory provides a fabric to the forest that controls the types, richness, and abundance of other biota through regulation of key functions and provision of critical resources. The compositional fabric varies across physical and chemical gradients of landscapes. Tree composition also changes over time with succession after disturbances. Forest management can cause equally important changes in the fabric of overstory composition.

In this chapter, we review the relationships that exist between overstory trees and other organisms in a forest and assess the ecological consequences of altering these relationships through forest management, namely, changing the compositional fabric. This understanding is essential to devise management strategies that both maintain biological diversity and sustain timber production. Methodologies for managing overstory composition often have a stand-level focus, but they also need to include a larger-scale perspective that considers the distribution and abundance of stand compositions across landscapes. To this end we discuss challenges and recommendations for developing and pursuing compositional goals for landscapes.