[MCN] Can't talk sustainability w/out talking about timescale

Lance Olsen lance at wildrockies.org
Fri Oct 14 13:29:24 EDT 2016

PNAS Early Edition published ahead of print October 11, 2016, 

Sackler Colloquium on Coupled Human and Environmental Systems - 
Biological Sciences - Sustainability Science:

Timescales and the management of ecological systems
Alan Hastings

Abstract [bold added]

Human management of ecological systems, including issues like 
fisheries, invasive species, and restoration, as well as others, 
often must be undertaken with limited information. This means that 
developing general principles and heuristic approaches is important. 
Here, I focus on one aspect, the importance of an explicit 
consideration of time, which arises because of the inherent 
limitations in the response of ecological systems. I focus mainly on 
simple systems and models, beginning with systems without density 
dependence, which are therefore linear. Even for these systems, it is 
important to recognize the necessary delays in the response of the 
ecological system to management. Here, I also provide details for 
optimization that show how general results emerge and emphasize how 
delays due to demography and life histories can change the optimal 
management approach. A brief discussion of systems with density 
dependence and tipping points shows that the same themes emerge, 
namely, that when considering issues of restoration or management to 
change the state of an ecological system, that timescales need 
explicit consideration and may change the optimal approach in 
important ways.
"These large recharge events are vital in replenishing and 
maintaining groundwater storage, especially after multiple years of 
below average precipitation across the region," said Melissa 
Masbruch, a hydrologist at the U.S. Geological Survey in Salt Lake 
City and lead author of the study. "Without them, groundwater 
resources become depleted."

Large groundwater recharge events are characterized by above-average 
annual precipitation and below-average seasonal temperatures, 
especially during the spring (April through June).

Alaska is getting warmer earlier in the year...Over the past 60 
years, the average annual temperature in Alaska has increased by over 
3 degrees Fahrenheit, with most of the change happening in winter and 


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