Forests serve crucial roles in regulating freshwater resources. When complex global change drivers interact with the equally complex structure of natural forest ecosystems, uncertainty is created as forests change in structure and function. Within a climate-modified forest stream, not all measurable ecological processes change in lockstep – some signals change quickly and may intiate a cascading sequence of changes. These changes are expected to occur at a higher rate in northern latitude forests. The following question was considered: Is there empirical evidence of climate change driving forest waters into a “new normal”? First, multivariate autoregressive models were applied to a cluster of forested watersheds to explore the interactive effects of climate change on hydrological and biogeochemical resiliency (reactivity and recovery rates). Second, indicators of shifts to alternative stable states were explored to identify which hydrological and biogeochemical constituents were driving loss of resiliency.
Results/Conclusions
Forests without wetlands showed higher reactivity but lower recovery rates in hydrological and biogeochemical exports. Forests without wetlands appear to be moving into a “new normal” defined by increased nitrogen (but decreased phosphorus) export to surface waters, with human-modified forested systems (e.g., managed forests) accelerating these changes.