Progress 09/16/18 to 09/30/19
Outputs
Target Audience:The target audiences for this research include students, the scientific community, and land managers. Students helped to conduct this research it will be included in a Master's thesis for Jalene Weatherholt. Results are still being processed, but will be submitted to a peer-reviewed publication within the next year. Presenting these results at local conferences (e.g. the Northwest Forest Soils Council meeting) will help to communicate these findings to agency and stakeholder communities. Changes/Problems:We ran into a few obstacles over the course of this project. Due to these delays, we plan to continue field monitoring for an additional year in order to collect sufficient data for analysis and publication. Graduate student personnel: There was graduate student turnover on this project which presented some challenges to data collection and sample processing. We discovered that the original student hired was not able to physically perform the required field work. A student from the Johnson lab helped to fill the gap before a new permanent student was found. The student currently handling the data is dedicated to the publication and completion of this project. Equipment failure and destruction: We had issues with some of the equipment malfunctioning in the field. Fortunately, data was monitored remotely and we were able to quickly dispatch a team to repair it leading to only small gaps in data. Additionally, we had overenthusiastic wildlife who caused some disturbance by using our poles for scratching posts, chewing through wires, and unplugging our sensors. We were able to correct these errors through additional trips to the field. During these trips, we anchored the posts for the logger boxes and stacked rocks to provide more stability, ran all sensors through conduit, and swapped out the logger boxes for a newly available model which included anchors for logger stereo cables. Deionized water malfunction and building flooding: In January 2019, a coil full of coolant burst in a winter storm and rained down through five floors of the primary research location at the University of Washington. Clean-up and decontamination from that event lasted several months, delaying the processing of samples. In a separate incident, the glass pipes for the deionized water system broke and flow of DI has been unavailable for over a year. The repair process is nearly complete and we will develop the soil water retention curves as soon as possible. What opportunities for training and professional development has the project provided?Students were the primary benefactors of professional development training for this project. Graduate students who were involved learned how to coordinate field work, navigate complex terrain, collect soil and plant samples, prepare and analyze laboratory data, and had the opportunity to practice scientific writing. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We measured soil physical and chemical characteristics at two sites in eastern Washington. Previously collected ring width data showed that one of these sites (Bear Canyon Ridge, BCR) had patterns of tree growth and stable isotope values that were highly correlated with winter precipitation, while tree growth at the other site, Foggy Dew (FOD), was less well correlated with winter precipitation. Stable isotopes from Foggy Dew were strongly correlated with summer precipitation. As a result, this study aimed to examine below-ground properties between sites as a potential mechanism underlying these differences in tree growth and stable isotope patterns. We deployed soil moisture and temperature sensors, collected surface soil samples for laboratory analysis, and measured incremental tree growth for two years. We found that soil conditions at FOD were less hospitable for the Ponderosa pine growing there. There was less water and nutrients and the soil experienced more extreme temperatures than at BCR. This indicates that trees at FOD may be limited more by soil conditions than direct climate effects and thus could explain why summer precipitation was a more important influence on tree isotopic ratios than winter precipitation. BCR, in contrast, is better able to buffer against summer environmental changes due to the more supportive soil habitat. As a result, any future changes in climate which exacerbate soil conditions (i.e. declines in precipitation or increased warming) will likely have a larger effect on tree survival at FOD. We collected microcores (short cores used to asses cambial growth) from BCR and FOD and found that there was more growth at BCR in a single season than at FOD, which can be linked to soil characteristics. These results are important for land managers as the harvest of Ponderosa pine has been a cornerstone of the timber industry in the American West since the 1860s. It will also influence the management of wild stands. Understanding the drivers of tree mortality in these forests will help us to protect this valuable resource for future generations.
Publications
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