Following the June 2017 Arlington Critical Zone Observatory (CZO) All Hands Meeting we drafted a white booklet to express the ideas generated and emphasize the knowledge shared during this meeting to the broader public. The document is divided into the following sections: 1) critical zone knowledge learned over the last decade, 2) compelling critical zone questions for the decade to come, 3) the next generation of critical zone observatories and approaches, and 4) critical zone education and outreach initiatives. The booklet will be available for public discussion through CZEN.org (see instructions below) through November 5th, 2017. We look forward to hearing your thought on how we can continue to grow CZ science into the future. Please leave your comment below and reference a specific line number in the document so that we can address your comments.
New Opportunities for Critical Zone Science white booklet (PDF)
Pamela L. Sullivan
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The April 2017 Arlington report is a nice comprehensive overview of what we know and where we need to go in integrative CZ science. It is my hope that the following comments can be reflected in the outcomes of the 2017 Arlington meeting.
Comments are prefaced by indicating that I am a co-investigator at the NSF Calhoun CZO and I also attended, presented, and aired the following ideas at the April 2017 Arlington CZ meeting. For some reason these views did not resonate into meeting the report, so I will use this opportunity to reiterate two comments.
The inclusion of millennial scale forcing by anthropogenic urbanization would broaden the impact of CZ science. This requires inclusion of international CZ programs beyond the NSF CZO network, as North America does not offer a written historical record of continuous millennial scale urban influence. This comment is in no way intended to deemphasize the importance of younger urban CZ sites as proposed in the report. Promotion of CZ science in other areas such as China and Middle East offer the double benefit of infilling global nodes of CZO’s data and the potential to extract millennial scale geo/biological records in concert with written human records. This point fits well within sections 1.9, 2.2 and 2.2.1 (1) of the report.
Clay minerals are some of the most reactive parts of the CZ, yet they are difficult to characterize. Clay minerals are mentioned once in the report in the context of how they control porosity and permeability of the CZ. Clay minerals are also very important in mediating biological reactive pathways, contaminant transport, slope stability, and other geophysical properties. The challenge of characterizing and quantifying clays and clay minerals in the critical zone needs to be uplifted in the report.
University of Georgia
The report reads very well. The lead writers did a great job of synthesizing a very large and diverse body of information from the meeting.
I attended the meeting, gave a presentation, and contributed some writing to the report. I am certainly happy with the way my contributed text was adapted and edited into the "Coastal margin" section starting at line 772. Nice improvements.
I was at the meeting representating a Canadian critical zone observatory and would thus be part of the international community of CZ scientists outside the US (and formally part of CZEN). I personally percieved a theme at the meeting that I could not find reflected in equal proportion in the report - based on a farily quick review. That is a theme of recognizing the value of international collaborations among CZ scientists and the important role that networks, funders, and institutions play in enabling transboundary CZ science. I respect that this may not be the focus of the report and I appologize if I just missed this in the document!
This white booklet serves as a road atlas for CZ scientists, putting advances to date in a broad context and offering well-reasoned pathways forward for the CZO program. I really enjoyed reading it and appreciate the authors' work - it is a very powerful document. I have a suggestion involving ideas #2 and #8 early in the document (at least, these seem like the best places to insert my thoughts if they are viewed as valuable). If adopted, modifying these ideas may prompt some subsequent changes in the text that follows. I think both ideas #2 and #8 may benefit by explicitly addressing the interactions b/n biota and geology. It seems like #2 would benefit from some mention of the idea that biota composition and nutrient acquisition strategies appear to depend on lithology (in systems where soil is derived from underlying bedrock). Biota don't just derive nutrient from underlying rock and dust - their very life history strategies are dictated by them, a concept demonstrated in spades in the Sierras wher P-rich and P-poor lithologies are juxtaposed. #8, in turn, could contain an acknowledgement that CZ architecture is also driven by biota, both past and contemporary (and may not be in equilibrium w/ current forcings). Here, I am thinking about the geomorphological and geochemical influence of multiple generations of vegetation. Making these changes would highlght what I think has been a key observation at all CZOs and indeed what has driven much CZO research - the concept that geology and biology *interacting* across moment-to-millennial timescales to govern CZ structure and function. Though the interdisciplinarity of CZ science is explicitly emphasized in the document as is, the geo-bio *interface* as its own driver is to a much lesser degree. This inter-weaving of these particular disciplines was an emergent theme of many of the talks and posters at Arlington and that spirit seems a bit understated in the document. Though there is wide appreciation of the importance of bio in geo, and geo in bio, across long timescales, the CZ perspective has enhanced that paradigm by revealing in exquisite detail how lithology can govern diverse landscape and ecosystem features such as geomorphology and nutrient acquisition strategies, and how biological processes can influence geochemical fluxes and, ultimately, rates of bedrock dissolution. Many of the ideas discussed in the booklet highlight or draw upon the idea that the interdisciplinarity of CZ science is what makes it shine, but it seems important to explicitly emphasize the intersection of these specific disciplines in the 10 ideas described.
Some thoughts from a relative newcomer to CZ science. -Sharon Billings, University of Kansas
The concept is inherent in much of what is discussed in the booklet but is never explicitly stated, yet this was one of the most overwhelmingly common
Comments regarding the New Opportunities for Critical Zone Science,
I have several comments on the draft document stated from the perspective of the Reynolds Creek CZO.
Data management. I think we should promote the idea of using doi’s to promote data use by the “public”.
Publishing specific datasets with associated doi’s has proven to be an effective way of conveying data to the scientific public, effectively archiving, and allowing the scientists who generate these datasets a means of obtaining credit. At RC, datasets describing the spatial distribution of soil carbon, mobile regolith depth and model forcing data have been published. We consider these to be a great compliment to other database initiatives described in the draft.
Around line 248.
There is evidence from RC that the amount of “green water” accessible to plants is controlled by lithology. Detailed water and energy balance data collected on two watersheds with volcanic (basalt and rhyolite) geology provide have shown a close correlation between the amount and timing of water passing through the root zone (1 to 2 m) and that measured as streamflow (Seyfried et al., 2009, Chauvin et al., 2011). The very rapid measured response of groundwater implies a highly permeable substrate with very low effective porosity, consistent with volcanic geology but also not likely to store rock moisture for plant use. The nature of subsurface flow paths and the amount of interannual communication between incoming and stored water are currently under investigation.
Around line 422.
The importance of linking models directly to processes, as opposed to surrogates for those processes, is becoming more evident as measuring and monitoring is intensified. The RCCZO recently collected extensive soil temperature data demonstrating approximately a 5 C mean annual soil temperature difference between adjacent slopes on contrasting aspects. This difference is sufficient to affect carbon cycling as well as mineral weathering in the immobile regolith. Contrary to many modeling approaches used to describe aspect effects (Biome BGC, EEMT), these temperature differences are not related to air temperature (which was equal), or the timing of differential solar radiation inputs (which was asynchronous), but rather the interactions between the land surface cover (e.g., snow cover, vegetation), within soil processes (heat transport and freezing) and incoming solar radiation. All processes captured with the SHAW model, which simulates simultaneous heat and water transport in freezing, vegetated soils, can effectively describe.
Under section 2.2.
Widespread, large scale highly destructive wildfire has become common place in the western US, costing lives, money, and extensive loss of ecosystem services in general. One way of minimizing the threat of such fires is to intentionally light smaller, controlled fires that reduce the fuel and hence risk of catastrophic fire. This carries with it obvious risks and leads to questions regarding how rapidly the system recovers. Work at RC CZO has shown that, under some conditions, the hydrologic recovery is rapid (Flerchinger et al., 2016), plant productivity resumes rapidly (Fellows et al., 2017 in review) and soil OM properties are not greatly affected (Chandler et al., 2017 in review) even while the above ground biomass is much less, thus reducing the fire hazard for some time.
Reasons for maintaining existing the current CZO network.
It seems to me that we should emphasize the idea that these observatories are cost effective resources for the broader scientific community to use. By supplying the “scientific infrastructure” of a data collection network, historic data and results, background information and facilities, research is conducted at the CZO’s that either couldn’t otherwise be accomplished, or could only be accomplished at much greater expense. This is true for work outside the expertise of the local CZO PI’s. RC, for example, has recently “hosted” research on bed load transport (Olinde and Johnson, 2015), soil water repellency (Chandler et al., ), remote sensing technology (Olsoy et al., 2016, Anderson et al., 2017), and downscaling regional forecast data (Cowley et al., 2017). In addition, we participate in different research networks (DIRT, LTAR, SMAP) that would be difficult for individual scientists to maintain.
One final comment regarding the Arlington Meeting; despite the considerable amount of research related to terrestrial carbon dynamics currently pursued at the CZO’s, there is a great reluctance to highlight that work or mention it as an important research objective for the future. From my perspective: 1. Understanding carbon dynamic s is the single most scientific important challenge of our time, and 2. The CZO network is the best place in the world today to advance research addressing that challenge. My reasoning behind the second point is that I think that the biggest reason that progress on the topic is not further advanced is that there hasn’t been sufficient infusion of the physical constraints and controls on carbon related processes. This includes “deep processes” that I think are an essential. Even though the current network is not ideally located for this challenge, it certainly provides a fantastic basis from which to work.
Anderson, K.E., Glenn, N.F., Spaete, L.P., Shinneman, D.J., Pilliod, D.S., Arkle, R.S., McIlroy, S.K., Derryberry, D.W.R. 2017. Methodological considerations of terrestrial laser scanning for vegetation monitoring in the sagebrush steppe. Environmental Monitoring and Assessment 189.10.1007/s10661-017-6300-0
Chandler, D. G., Cheng Y., Seyfried, M.S., Madsen, M. D., Johnson, C. E., and Williams, J. W. Seasonal wetness, soil organic carbon and fire influence soil hydrological properties and water repellency in a sagebrush-steppe ecosystem. Water Resources Research, in review.
Chauvin, G.M., Flerchinger, G.N., Link, T.E., Marks, D., Winstral, A.H., Seyfried, M.S. 2011. Long-term water balance and conceptual model of a semi-arid mountainous catchment. Journal of Hydrology 400:133-143.10.1016/j.jhydrol.2011.01.031
Cowley, G.S., Niemann, J.D., Green, T.R., Seyfried, M.S., Jones, A.S., Grazaitis, P.J. 2017. Impacts of precipitation and potential evapotranspiration patterns on downscaling soil moisture in regions with large topographic relief. Water Resources Research 53:1553-1574.10.1002/2016WR019907
Fellows, A. Flerchinger, G., Lohse, K.A., and Mark Seyfried, Rapid recovery of gross production and respiration in a mesic mountain big sagebrush ecosystem following prescribed fire Ecosystems, in review.
Flerchinger, G.N., Seyfried, M.S., Hardegree, S.P. 2016. Hydrologic response and recovery to prescribed fire and vegetation removal in a small rangeland catchment. Ecohydrology 9:1604-1619.10.1002/eco.1751
Olinde, L. ,Johnson, J.P.L. 2015. Using RFID and accelerometer-embedded tracers to measure probabilities of bed load transport, step lengths, and rest times in a mountain stream. Water Resources Research 51:7572-7589.10.1002/2014WR016120
Olsoy, P.J., Mitchell, J.J., Levia, D.F., Clark, P.E., Glenn, N.F. 2016. Estimation of big sagebrush leaf area index with terrestrial laser scanning. Ecological Indicators 61:815-821.10.1016/j.ecolind.2015.10.034
Seyfried, M.S., Grant, L.E., Marks, D., Winstral, A., McNamara, J. 2009. Simulated soil water storage effets on streamflow generation in a mountainous snowmelt environment, Idaho, USA. Hydrological Processes 23:858-873.DOI: 10.1002/hyp.7211
A few comments about the role of topography and vegetation in CZ science.....
435 - insert "Topography also affects, microclimates, organizes subsurface water flow, and constrains vegetation and snowpack distributions (e.g. Tennent et al., 2017); influencing both the reservoirs of the critical zone and setting the stage for critical zone processes.
655 - insert "We must be able to quantify, for example, where water is stored and for how long, where plants access nutrients, how vegetation is distributed across the landscape, and how deep and at what rate carbon can be moved through the subsurface. " We must understand how vegetation communities are distributed across watersheds, and their respective contributions to soil organic carbon, and overall carbon loss from disturbances such as fire (Li et al., 2015, Poley et al. in preparation, Will et al 2017)".
804 - insert cross-CZO Tennent et al 2017 study " Regional warming will result in changes in snowpacks, and the sensitivity of these snowpacks to temperature-driven shifts from snow to rain and changes in wind speed and vegetation will ultimately affect available streamflow (Tennent et al., 2017)."
Li, A., Glenn, N.F., Olsoy, P.J., Mitchell, J.J., Shrestha, R., 2015, Aboveground biomass estimates of sagebrush using terrestrial and airborne LiDAR data in a dryland ecosystem, Ag & Forest Met, 213: 138–47. doi:10.1016/j.agrformet.2015.06.005.
Poley, A., Glenn, N., Spaete, L., Mitchell, J., Dashti, H., Hyperspectral derived vegetation species and cover across landscape gradients in semi-arid ecosystems using multiple endmember spectral mixture analysis coupled with optimal endmember bundling in preparation.
Tennant, C. J., A. A. Harpold, K. A. Lohse, S. E. Godsey, B. T. Crosby, L. G. Larsen, P. D. Brooks, R. W. Van Kirk, and N. F. Glenn (2017), Regional sensitivities of seasonal snowpack to elevation, aspect, and vegetation cover in western North America, Water Resour. Res., 53, doi:10.1002/2016WR019374.
Will, Ryan M.; Benner, Shawn; Glenn, Nancy F.; Pierce, Jennifer; Lohse, Kathleen A.; Patton, Nicholas; Spaete, Lucas P.; and Stanbery, Christopher. (2017). Mapping Soc Distribution in Semi-arid Mountainous Regions Using Variables From Hyperspectral, Lidar and Traditional Datasets [Data set]. Retrieved from https://doi.org/10.18122/B2Q598