Thursday, January 20, 2022

Are Long-term Data Sets Worth the Effort at Biology Field Stations?

For the past 11 years, I have been maintaining equipment and curating data sets for environmental monitoring at University Farms of Case Western Reserve University.  Although the original deployment of was part of my research on Great Lakes ecosystems, the environmental monitoring program at the CWRU Farm became a general resource for research and education.  The original monitoring began with two weather stations, one in an open field and the other in the north woodlot.  Later, we added hydrology monitoring of the experimental watershed and additional environmental monitoring associated with the Farm’s Food Production Program.  The former Farm Director, Dr. Ana Locci, supported and encouraged this work as part of an effort to improve the research and education infrastructure at the Farm.  Our partnership on environmental monitoring platforms deepened with the arrival of Beech Leaf Disease (BLD) at the Farm in 2017 and led to incorporation of a remote sensing platform with the addition of an unmanned aerial vehicle and sensors to monitor changes in forest canopies associated with the spread of BLD.  I summarized preliminary findings of this work in previous posts.  In this post, I want to reflect on the value of long-term monitoring at a university field station.

The motivation for this reflection has arisen from both personal and institutional changes in priorities.  As with many things over the last two years, the Covid-19 pandemic has contributed to reassessment of research and education initiatives at the Farm.  With Dr. Locci’s retirement as Farm Director in 2020, the environmental monitoring program lost its primary institutional sponsor.  In the hiatus following her retirement, restrictions on activities associated with the University’s Covid protocols, led to shorter-term reassessment of priorities of Farm management and activities of the Biology faculty involved with the Biology Field Station.  Along with these changes and changes in my personal priorities, the environmental monitoring program has now ended.  Only the weather station in the north woodlot and a weather station at the November Greenhouse continue operating, and this will be the last year for which the remote data logger in the north woodlot will report data over a 3G network.  Recently, however, some CWRU faculty have asked for access to historical environmental data.  In particular, Dr. Mark Green and his undergraduate student, Kyle Rickert, have analyzed some of the weather station data as part of a small project to measure sap flux in beech trees of the north woodlot.  Although I had proposed providing a data archiving platform for Farm data in 2018, I haven’t kept up with documenting a wide range of problems with the monitoring platforms.  Various probe failures, data gaps, and difficulties accessing historical data made it difficult to give others access to a consistent set of time series from various probes.  Stimulated by Green and Rickert’s preliminary analyses of partial data sets, I have now finished a complete review of the data and am distributing the consolidated data from the weather station to interested researchers.

In their partial analysis of soil moisture data from the north woodlot weather station, Green and Rickert found some recent increases in the soil moisture that reinforced their observations of reduced sap flux in BLD infected beech trees.  Previously, Dr. Locci and I had identified a pattern of increased solar radiation in the north woodlot where damage to beech was acute.  To me, the following Figures 1 and 2, prove the importance of maintaining long-term environmental monitoring at the Farm.  

In my first post on BLD incidence at the Farm (2017 post), I noted that the ratio of solar radiation measured at the weather stations of the north woodlot and open field had nearly doubled from a about 6% prior to 2017 to about 12% in 2017 during the summer.  As illustrated in Fig. 1, this trend continued after 2017 with the ratio approaching 19% in the summer of 2021.  Fig. 2 also shows a substantial change in soil moisture from 2017 to 2021.  Over the period of 2009 to 2016, minimum fall soil moisture (m3/ m3) ranged from 0.02 to 0.1, except for 2014.  From 2017 to 2021, minimum soil moisture increased to 0.1 in 2017 and 2018 and then to 0.22 in 2021.  




Conclusion

The eastern part of the north woodlot is a remnant primary forest with a predominant beech-maple assemblage. Beech Leaf Disease is only the latest stressor on beech in northeastern Ohio.  Beech bark disease has also impacted the beech area of the north woodlot.  The cumulative stress on beech trees is evident is the loss of large old beeches.  Without the long-term data sets from the weather stations, however, it would have been difficult to detect the timing of the consequences of these stressors.  The increases in the fall soil moisture from 2017 correspond most closely with the outbreak of Beech Leaf Disease.  It would thus seem prudent to continue this environmental monitoring program.