Wednesday, June 3, 2009
Thursday, April 23, 2009
The questions presented provide an interesting look over the horizon and suggest emerging issues and concerns. Because the five questions related to Freshwater Ecosystems (#54-58) are of particular interest to me, I list them in full below:
- How can freshwater biodiversity and ecosystem service values best be incorporated in the design of water-provisioning schemes for direct human use and food production?
- Which aquatic species and communities are most vulnerable to human impacts, and how would their degradation affect the provision of ecosystem services?
- Where will the impacts of global climate change on hydrology be most extreme, and how might they affect freshwater species and the ability of wetlands and inland waters to deliver ecosystem services?
- Which multinational governance, cross-sector cooperation arrangements, and finance mechanisms will make freshwater ecosystem management more effective and reduce international conflicts over water?
- How does investment in restoration of wetlands and riparian areas compare with construction of dams and flood defenses in providing cost-effective improvements in flood management and the storage and retention of water for domestic, industrial, and
The third question, related to climate change impacts on freshwater systems, is particularly relevant to those of use living in mid-continent, mid-latitude locations, a fact underscored by a feature article in today's Strib on water quality in west-metro lakes. Reduced rainfall last summer appeared to limit external nutrient loading thus resulting in clearer water. In contrast, and more locally, our data from Grace Lake suggest that longer hotter summers, which result in extended periods of stratification and consequent increased internal loading, will result in dramatic increases in mid-summer algal growth with corresponding shifts in fish communities and overall aesthetic appeal. In any case, a changing climate will fundamentally reshape the dynamics of ecological processes in our lakes and rivers (in ways we are only beginning to understand).
Note: The fifth freshwater question is also especially relevant regionally given the extent of northern Minnesota wetlands and the on-going flood related issues in the Red River Valley.
Wednesday, April 8, 2009
Wednesday, March 18, 2009
Tuesday, March 17, 2009
In the course of looking for something else, I came across a fascinating paper on "urban metabolism" (see pdf of Bettencourt, L. and others. 2007. Growth, innovation, scaling, and the pace of life in cities. Proc. Natl. Acad. Sci. USA 104(17): 7301-7306 ). Among many other interesting things, this article shows that mean walking speed increases as function of population (see top figure). For those not familiar with natural logarithmic scales, what the figure shows is that in a city of around 3000 people (~e8), average walking speed is about 1 meter per second (e0) . In a village of 400, average walker velocity slows to roughly 0.8 meters per second while in a city of 1.2 million the typical pedestrian is hustling along at 1.5 meters per second.
Two things are remarkable about this finding. First, and as is shown in the lower figure, metabolic rates of individual organisms typically decrease as body size increases. Somehow, cities as organic entities function in a way that is fundamentally different than what we see in individual animals. Second, the incredibly tight scaling of walking speed to city size is extraordinary. That such a basic human behavior is so closely tied to population density has profound implications for the way we perceive the world.
As I have worked with lakshore property owners from around Minnesota over the past couple years I have often been struck by the starkly contrasting perspectives of urban and rural residents. Perhaps this work offers a hint at why what we value here in northern Minnesota is so different than what is valued by residents of the Twin Cities metropolitan area. If population density can influence our mean walking speed is it any wonder that it might also influence more subtle attitudes and behaviors?
'...what that must do to their souls, how different they must be in their private concerns and evaluations and wishes.' -- Dean Moriarty, in Kerouac's 'On The Road'
Thursday, March 5, 2009
One excellent place to start would be to provide signage at accesses discouraging the now almost ubiquitous practice of power-loading (i.e., driving your boat on to the trailer) . Power-loading produces a pronounced scour hole and wide spread sedimentation at just the place where invasive species are most likely to enter a lake. In effect, power-loading is equivalent to putting out a welcome mat for Eurasion watermilfoil and other invasive plants. With spring just around the corner, it is time to think about such things...