Lepidoptera larvae (caterpillar) abundance and biomass in the northern hardwood forests of central New Hampshire, USA, shows large interannual fluctuations in aggregated caterpillar biomass (21-fold variation in caterpillars/ 8000 leaves) that were spatially correlated across a regional landscape. Primary production of these mature forests has not varied over this period, and many hundreds of Lepidoptera species share comparatively few host plants.

Long-term base cation depletion from soils appears to be detrimental to the health and productivity of hardwood forests in the northeastern U.S. Understanding and predicting forest responses to acidic deposition and changes in soil chemistry would benefit from better knowledge of limitations to soil microorganisms, given their critical role mediating the supply of essential nutrients to plants.