Spatial Patterns of Canopy Disturbance, Structure, and Species Composition in a Multi-Cohort Hardwood Stand

Abstract

Multi-cohort stands are increasingly recognized and valued because of their biological functioning, biological diversity, and resistance and resiliency to perturbations. These forest ecosystems are epitomized by multiple age classes, and often contain multiple canopy layers, a range of tree size classes, and large amounts of woody debris. Disturbance history reconstructions in multi-cohort stands provide an understanding of the processes that create these systems. In this study, we documented structure and composition, and used dendroecological techniques to reconstruct disturbance history on a 1 ha plot in a multi-cohort hardwood stand in the Fall Line Hills of Alabama. The stand was dominated by Quercus alba L. and Liriodendron tulipifera L. Mingling index and stem maps indicated that most species were well dispersed throughout the stand, with the exception of L. tulipifera and Carya tomentosa (Poiret) Nuttal, which were relatively clustered. The oldest trees in the stand established in the 1770s, however, the largest recruitment event occurred ca. 1945 in conjunction with a stand-wide canopy disturbance. We posit that spatial heterogeneity of canopy removal during this event was largely responsible for the observed compositional and spatial complexity documented in the stand. In addition to the 1945 event, we recorded another stand-wide canopy disturbance in 1906 and 84 gap-scale disturbance events from 1802 to 2003. The conditions documented in the stand can be used as a benchmark to guide the creation and maintenance of complex multi-cohort stand characteristics, an increasingly popular management goal.

What Are Intermediate-Severity Forest Disturbances and Why Are They Important?

“…In fact, in many forest types, more than one intermediate-severity disturbance is likely to occur during the lifespan of the dominant trees. In Quercus stands of the eastern USA for example, the return interval of intermediate-severity disturbance events based on tree-ring records has been found to range from 20-50 years [94][95][96][97][98][99][100]. An intermediate-severity disturbance return interval of ca.…”

Wildfire Alters Spatial Patterns of Available Soil Nitrogen and Understory Environments in a Valley Boreal Larch Forest

“…Plants can also impact the spatial pattern of soil resources by altering physical, chemical and biological soil properties [6][7][8]. However, recent studies have found that these interactions and the potential heterogeneity across landscapes could be modified by disturbances [9][10][11]. Wildfire is one of the most important natural ecological disturbance agents in forest ecosystems, is characterized by variations in fire severity and frequency [12,13], and therefore produces spatial and temporal variations in ecological systems.…”

Incorporating Intermediate-Severity Disturbances in Oak Stand Development

“…Disturbance history reconstructions using tree-ring records and forest inventory data have been conducted in some oak stands of the eastern USA. The studies have shown that the return interval of disturbance events that removed trees from at least 25% of the stand was typically 20-50 years [6,26,[56][57][58][59][60][61]. Disturbances of this spatial extent and severity would be classified as intermediate-scale events.…”