Late-successional riparian forests often regulate autotrophic microhabitats in low-order streams through shading provided by canopies. However, few studies have linked forest structure with periphyton microhabitat in adjoining streams. Our hypotheses were that (1) the heterogeneous horizontal structure in old-growth forests creates more spatially variable below-canopy light environments compared with mature forests and (2) site-specific light availability over streams correlates with spatial distributions of periphyton microhabitat. We surveyed 15 low-order stream reaches in late-successional northern hardwood–hemlock forests in the Adirondack Mountains of New York, USA. We measured forest structure and the below-canopy light environment at all reaches and the periphyton chlorophyll a concentration on artificial substrates in eight reaches. While stand age was not statistically significant, multivariate models of horizontal forest structure (e.g., gap distribution) and topography showed strong relationships (R² > 0.70) with the below-canopy light environment across all late-successional forests. Furthermore, metrics of below-canopy light availability explained a small but statistically significant proportion of the variation in chlorophyll a concentration. This variation in chlorophyll a indicates that complex late-successional riparian forests, both mature and old-growth, create a mosaic of heterotrophic (shaded) and autotrophic (lighted) microhabitats along low-order streams. These results reveal important and previously unrecognized links between stream habitat heterogeneity and the horizontal heterogeneous late-successional forest structure.

Clonal forestry is becoming a reality in the southeastern United States owing to recent improvements in somatic embryogenesis for Pinus taeda (L.). D

Weed control and overstory reduction are important silvicultural treatments for improving survival and growth of under‐planted oak and hickory seedlings. Mast‐producing trees in the bottomland forests of the blackland prairie and Post Oak Savannah ecoregions of Texas have declined in abundance. Oaks and hickories have been replaced by more shade‐tolerant species, including green ash (Fraxinus pennsylvanica Marshall) and sugarberry (Celtis laevigata Willd.), which do not produce significant hard mast for priority wildlife species. A split‐plot experiment design was installed on three sites at Richland Creek Wildlife Management Area in Freestone County, Texas, studying the effects of canopy coverage and competition control on survival and growth of bur oak (Quercus macrocarpa Michx.), Shumard oak (Quercus shumardii Buckl.), and pecan (Carya illinoinensis (Wagenh.) K. Koch) seedlings. Uprooting by hogs shortly after planting resulted in greater than 90% mortality of pecan on the two lower elevation sites. Year one survival of Shumard oak was significantly higher than bur oak. However, bur oak was more preferred by hogs than Shumard oak. Year one growth of bur oak was significantly greater than Shumard oak. Severe flooding during the second growing season caused complete mortality on the lower two sites. None of the species were well suited to such prolonged (3–4 months) inundation as seedlings. On the remaining site, density reduction and weed‐barrier mats improved growth and survival while herbaceous weed control with herbicides actually reduced both growth and survival.