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University of Michigan Biological Station

The University of Michigan Biological Station (UMBS) was founded in 1909.

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Interacting disturbance in forest ecosystems: Does disturbance memory affect resistance and resilience of forest productivity?

Project Abstract: 
Global change is altering disturbance regimes in terrestrial ecosystems, leading to more frequent and intense interactions among disturbances, which can result in compounding effects on ecosystem structure and function. One aspect of disturbance interactions that is poorly understood is the role of structural and functional legacies (or “memory”) of initial disturbance on the resistance and resilience of the ecosystem to subsequent disturbance. In forested ecosystems structural and functional characteristics of the canopy are an important component of ecosystem memory that likely strongly mediates the effect of interacting disturbances on ecosystem functioning, but is also strongly affected by variation in initial disturbance severity. The research program detailed here evaluates how disturbance memory (in the form of altered canopy structure and functional traits) affects ecosystem resistance and resilience to subsequent disturbance. A new experimental defoliation method will be overlaid onto an existing long-term experimental disturbance study to create a novel disturbance interaction experiment. The seed project proposed here will develop the methodology to produce canopy defoliation, assess effects of defoliation on canopy structure, and collect preliminary data on short-term disturbance resistance. The experimental framework, novel methods, and preliminary data collected in this seed project will form the basis for a subsequent proposal to the National Science Foundation Division of Environmental Biology Ecosystem Science Cluster, which will develop and test a new conceptual framework on the role of ecosystem memory in ecosystem response to disturbance. The work made possible by the seed funding will transform our understanding of the effect of disturbances (and altered disturbance regimes related to global climate change) on ecosystem functions such as C sequestration, which can be used to parameterize terrestrial ecosystem models and enhance our ability to predict the future of the globally important terrestrial C sink.
Investigators: 
rfahey
Status of Research Project: 
Active
Related projects: 
Forest Accelerated Succession ExperimenT (FASET)
Years Active: 
2019
Research sites: 
UMBS FASET Tower
Methods: 
The proposed project will be implemented within the FASET footprint, but outside the area of the intensive plots. Within FASET, sites have been identified that are appropriate locations to implement experimental defoliation, test the hypotheses of the proposed seed project, and potentially implement a larger subsequent expanded longer-term project. Rectangular 20 x 10m plots will be established in areas categorized according to initial disturbance severity as follows: low (10-20% mortality), moderate (30-50%), high (60-70%), and no disturbance (<5%). Two levels of defoliation will be tested, but only the light treatment will be replicated across initial disturbance severity categories (3 replicates per category, 12 total manipulated plots. The seed project will develop the methodology to produce required defoliation levels, assess effects of defoliation on canopy structure, collect preliminary data on short-term disturbance resistance (refoliation and NPP response). Defoliation will be accomplished with a heavy-duty power washer raised into the canopy using the "ZEKE" mobile canopy access vehicle. Defoliation using a power washer system has been tested by the PI on a tree level scale, the seed proposal will allow for testing and documentation on a multi-tree, plot-level scale. Based on initial tests, defoliation of the canopy of a single 20 x 10m plot will likely require 6-8 hours of work. Measurements and analysis included in the seed project will focus on documenting experimental defoliation methods, effects on canopy structure, and near-term forest productivity response.