Overview of eastern dendroecology and new directions

Background/Question/Methods

Dendroecology, using patterns of annual tree-ring growth to study a variety of ecological events, has contributed significantly to our understanding of forest dynamics.  In its infancy, this field was dominated by characterizations of stand-ages derived from cut stumps and increment borers.  The advent of precise measuring devices, computers, and specific formulas for characterizing tree growth responses to disturbance led to very detailed examinations of gap and stand dynamics throughout eastern forests.  Remaining old-growth forests became the focus of dendroecological interest, examining them to determine the intensity and frequency of past disturbance events like wind, ice, fire and forest pests.  Coupling land-use history data with these disturbance signals provided greater opportunities to elucidate individual species’ life history requirements, tree recruitment and coexistence patterns, and successional trends.  For example, oak recruitment in many forests increased following periodic historical disturbance events, but recent disturbances have favored more shade-tolerant trees like maple over oak. 

Results/Conclusions .

Tree sampling intensity has increased over larger plots and across a larger array of sites, enabling the detection of landscape-level and regional patterns of disturbance.  Lessons learned from dendroecology are increasingly being used to inform managers interested in emulating natural disturbances in silvicultural practices.  Recent studies of disturbance dynamics in northeastern old-growth hemlock-northern hardwood forests have provided guidelines for restoring late-successional and old-growth forest structure in second growth stands.   Additional new advances in dendroecology include documenting links between tree growth rates and lifespan, carbon storage levels in eastern forests, deciphering multiple interacting factors influencing forest growth and function, and understanding the various impacts of newly introduced invasive forest pests on tree growth.  Insects like hemlock woolly adelgid (Adelges tsugae), emerald ash borer (Agrilus planipennis), European wood wasp (Sirex noctilio), and Asian longhorned beetle (Anoplophora glabripennis) have recently invaded portions of eastern forests, and dendroecological investigations of their impacts are extremely helpful in understanding insect dynamics within a stand, throughout a region, and responses of host trees to these novel pests.  As climate continues to interact with trees and pests, dendroecology will continue to be a valuable tool in understanding and possibly predicting forest dynamics and function.