This MTNCLIM Conference was the first western mountain climate science conference modelled after the successful Pacific Climate (PACLIM) conference and sponsored by CIRMOUNT, the Consortium for Integrated Climate Research in Western Mountains—a working group of scientists from a range of agencies and universities, including the Mountain Research Institute (MRI). MTNCLIM aims to advance the sciences related to climate and its interaction with physical, ecological, and social systems of western North American mountains. Within this arena, MTNCLIM goals are to:
Highlights from the MRI perspective
Steve Gray of the USGS Desert Laboratory in Tucson, Arizona, gave an invited talk in which he linked perspectives derived from paleo-reconstructions of precipitation to both ecosystem dynamics and management of western resources. The paleo-record clearly shows that wet periods—and not droughts—are the anomalies of western climate. Beyond that, the pattern is far more complicated than a simple alternating of wet and dry periods. The record manifests a variety of frequencies, from inter-annual variation to multi-decadal regimes. Extended droughts result in extensive vegetation mortality. Subsequent wet years restart vegetation demography as well as launching colonization of new habitat. At larger scales, these disturbances may, like wildfire, create their own “weather,” that is, generate endogenous novel dynamics. On an institutional level, regime shifts are often conflated with management (the debate regarding the management or, alternatively, climatic origins of fuel build up in western forests being a prime example). Furthermore, persistent regimes produce an ossification of management rules that leads to surprise and maladaptation when the next regime shift occurs.
Indeed, a new CIRMOUNT work group has as its mission to explore the creation of an “up-to-date, spatially focused network of reconstructions to assist water resources managers in long term planning.” This specific focus might be useful for at least a few of the Global Change in Mountain Regions (GLOCHAMORE) Mountain Biosphere Reserves (MBRs)—as it has not been included so far in GLOCHAMORE's research strategy—as well as in Central Asia, the subtropical Andes, and other arid mountain ranges.
Tom Whitham of Northern Arizona University in Flagstaff, Arizona, focused on community and evolutionary consequences of the extended drought in the Southwest, providing a much more nuanced view of vegetation response than the “shifting band” perspective. Tree mortality is the key consequence of the Southwest drought. As the tree species in question are keystone species, their mortality reverberates through the structure of plant, bird, mammal, and arthropod communities. The extensive mortality has evolutionary consequences both through population bottlenecks and, because mortality is recurrently site specific, the possibility of local genetic adaptation. Whitham emphasized that ecological interpretations are very likely to be fundamentally revised, and even reversed, once data sets have a duration sufficient to cover the full suite of selective forces. For instance, after nearly two decades of study he was ready to conclude that an insect-resistant morph of pinyon pine was bound to eventually dominate the population, only to find that insect-resistant morphs were three times as likely to die from drought, suggesting that the multiple disturbances of drought and insects maintained the polymorphism of the population. More information about these lines of research can be found on the DIREnet–Drought Impacts on Regional Ecosystems network web-site: www.mpcer.nau.edu/direnet.
For a variety of regions, MRI has focused on recruitment of woody vegetation into higher alpine areas. Whitham's work is a reminder that it is equally important to understand mortality at the lower edge of the mountain forest. While this may or may not be important in Europe, it is important in MBRs in semi-arid regions.
Alex Hall of UCLA gave a very intriguing talk on the use of a fine-grained (6-km grid cell) RCM (regional climate model) to investigate the impacts of southern California mountains on precipitation and wind events. He and his colleagues drove the model with observed boundary conditions from 1995 to the present, and found very high correlation with observed weather data. The model successfully predicted the circulation modes associated with extreme wet and dry conditions in southern California. The mountains themselves are implicated in the generation of offshore Santa Ana winds and in the pattern of precipitation across the basin. Along with another presenter, Ruby Leung of the Pacific Northwest National Laboratory, he argued convincingly that the creation of RCMs for key mountain regions is feasible and ought to be a main part of the GLOCHAMORE research strategy.
Many other papers and participants deserve mention: Sam Ear-man of the Desert Research Institute in Reno, Nevada and Mark Williams from University of Colorado at Boulder discussed isotope studies that showed the importance of snow melt to groundwater, and the subsequent importance of groundwater in runoff. Mitch Plummer's paper on the simulation of mountain glaciers gave the impression that he worked at the University of Zurich rather than the Idaho National Engineering and Environmental Lab. Pam Sousanes of Denali National Park explained the Natural Park Service (NPS) Climate Monitoring Program, which would have greatly pleased Bruno Messerli.
More information on the conference can be found at http://www.fs.fed.us/psw/mtnclim/