Climate Change

Andrew's Glacier Study Site. Photo credit: Ed Hall/USGS.

As the earth system changes in response to human activities, a critical objective is to predict how biogeochemical process rates (e.g. nitrification, decomposition) and ecosystem function (e.g. net ecosystem productivity) will change under future conditions. A particular challenge is that the microbial communities that drive many of these processes are capable of adapting to environmental change in ways that alter ecosystem functioning. Despite evidence that microbes can adapt to temperature, precipitation regimes, and redox fluctuations, microbial communities are typically not optimally adapted to their local environment. For example, temperature optima for growth and enzyme activity are often greater than in situ temperatures in their environment. Here we discuss fundamental constraints on microbial adaptation and suggest specific environments where microbial adaptation to climate change (or lack thereof) is most likely to alter ecosystem functioning. Our framework is based on two principal assumptions. First, there are fundamental ecological trade-offs in microbial community traits that occur across environmental gradients (in time and space). These trade-offs result in shifting of microbial function (e.g. ability to take up resources at low temperature) in response to adaptation of another trait (e.g. limiting maintenance respiration at high temperature). Second, the mechanism and level of microbial community adaptation to changing environmental parameters is a function of the potential rate of change in community composition relative to the rate of environmental change. Together, this framework provides a basis for developing testable predictions about how the rate and degree of microbial adaptation to climate change will alter biogeochemical processes in aquatic and terrestrial ecosystems across the planet. http://www.today.colostate.edu/story.aspx?id=6416#

For more information contact, Ed Hall.

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These rice plants show the difference in growth of rice plants exposed to salt when grown with and without endophytes, which are mutually beneficial microscopic fungi that live in most plants. The plant on the left was colonized with a fungi that made it salt-tolerant, but it wasn't exposed to salt; the plant in the middle was colonized with a fungi that made it more salt-tolerant, and it was exposed to salt; and the plant on the right was the normal rice variety without the fungi and exposed to salt. The difference is dramatic (click to enlarge). Photo credit: Russell “Rusty” Rodriquez/USGS

Climate change and catastrophic events have contributed to rice shortages in several regions due to decreased water availability and soil salinization.  Although not adapted to salt or drought stress, two commercial rice varieties achieved tolerance to these stresses by colonizing them with Class 2 fungal endophytes isolated from plants growing across moisture and salinity gradients.
Plant growth and development, water usage, ROS sensitivity and osmolytes were measured with and without stress under controlled conditions. The endophytes conferred salt, drought and cold tolerance to growth chamber and greenhouse grown plants. Endophytes reduced water consumption by 20-30% and increased growth rate, reproductive yield, and biomass of greenhouse grown plants.  In the absence of stress, there was no apparent cost of the endophytes to plants, however, endophyte colonization decreased from 100% at planting to 65% compared to greenhouse plants grown under continual stress (maintained 100% colonization). These findings indicate that rice plants can exhibit enhanced stress tolerance via symbiosis with Class 2 endophytes, and suggest that symbiotic technology may be useful in mitigating impacts of climate change on other crops and expanding agricultural production onto marginal lands. Read the USGS Press Release: "Climate Adaptation of Rice"
The article is available at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0014823

For more information contact Russell “Rusty” Rodriquez.

See also Climate Change: Carbon Cycling >>

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