An official website of the United States government
The Caldor fire burned ~222,000 acres of the Eastern Sierra Nevada during summer–fall 2021. We evaluated the effects of this “megafire” on the physical properties of a sandy soil developed from glacial tills to document fire-induced soil modifications in this region. We measured soil water retention and hydraulic conductivity functions as well as the thermal properties of five core samples from control (unburned) areas and eight core samples from burned soil of the same soil unit. Soil water repellency was measured in terms of water drop penetration time (WDPT) in the field and apparent contact angle in the laboratory on control and burned soil as well as ash samples. Soil organic matter (SOM) and particle and aggregate size distributions were determined on control and burned soil samples. Additionally, scanning electron microscopy (SEM) was used to image microaggregates of control and burned soil samples. We found a significant difference in SOM content and sand and silt aggregate size distribution between control and burned samples, which we associated with the disintegration of microaggregates due to the fire. We found no significant difference between soil water retention and hydraulic conductivity functions of control and burned soil but observed greater variation in saturated hydraulic conductivity and systematic shifts in thermal conductivity functions of burned compared to control samples. WDPT and apparent contact angle values were significantly higher for burned soils, indicating the occurrence of fire-induced soil hydrophobicity (FISH). Interestingly, the average apparent contact angle of the control soil was >90°, indicating that even the unburned soil was hydrophobic. However, the ash on top of the burned soil was found to be hydrophilic, having apparent contact angles <10°. Our results indicate that SOM and microaggregates were readily affected by the Caldor fire, even for sandy soil with a weakly developed structure. The fire seemed to have moderated thermal properties, significantly and soil wettability but had only minimal effects on water retention and hydraulic conductivity functions. Our findings demonstrate the complex nature of fire-soil interactions in a natural environment and highlight the need for additional investigation into the causes and processes associated with FISH and structure alterations due to fire to improve our ability to rapidly determine potential problem areas in terms of hazards commonly associated with fire-affected soils.
more »
« less
Biogeochemical and 13C NMR data from NEON surface mineral soils
To understand controls on soil organic matter chemical composition across North America, we collected 13C NMR spectra and conducted and synthesized additional biogeochemical measurements from NEON Megapit soil samples as well as additional samples (total n = 42). This dataset supports the findings described in the associated manuscript by Hall, Ye et al. (2020).
more »
« less
- PAR ID:
- 10387388
- Publisher / Repository:
- Environmental Data Initiative
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Soil element concentrations (Na, Mg, K, Ca, Al, Mn, Fe, Si, Sr, and Ba) were measured in salt exchangeable extracts of soil samples taken in July 2017 in the MELNHE study, specifically in Bartlett stands C1-C9 and Hubbard Brook stands HBM and HBO. Additional detail on the MELNHE project, including a datatable of site descriptions and a pdf file with the project description and diagram of plot configuration can be found in this data package: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=344. Additional analysis data on these samples can be found in the dataset "Soil properties in the MELNHE study at Hubbard Brook Experimental Forest, Bartlett Experimental Forest and Jeffers Brook, central NH USA, 2009 - present" (https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=165). This work is a contribution of the Hubbard Brook Ecosystem Study. Hubbard Brook is part of the LTER network, which is supported by the US National Science Foundation. The Hubbard Brook Experimental Forest is operated and maintained by the US Department of Agriculture, Forest Service, Northern Research Station.more » « less
-
{"Abstract":["Soil element concentrations (Na, Mg, K, Ca, Al, Mn, Fe, Si, Sr, and\n Ba) were measured in salt exchangeable extracts of soil samples taken\n in July 2017 in the MELNHE study, specifically in Bartlett stands\n C1-C9 and Hubbard Brook stands HBM and HBO.\n\n \n Additional detail on the MELNHE project, including a datatable of site\n descriptions and a pdf file with the project description and diagram\n of plot configuration can be found in this data package:\n https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=344.\n\n \n Additional analysis data on these samples can be found in the dataset\n "Soil properties in the MELNHE study at Hubbard Brook\n Experimental Forest, Bartlett Experimental Forest and Jeffers Brook,\n central NH USA, 2009 - present"\n (https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=165).\n\n \n This work is a contribution of the Hubbard Brook Ecosystem Study.\n Hubbard Brook is part of the LTER network, which is supported by the\n US National Science Foundation. The Hubbard Brook Experimental Forest\n is operated and maintained by the US Department of Agriculture, Forest\n Service, Northern Research Station."]}more » « less
-
null (Ed.)A major limitation to building credible soil carbon sequestration programs is the cost of measuring soil carbon change. Diffuse reflectance spectroscopy (DRS) is considered a viable low-cost alternative to traditional laboratory analysis of soil organic carbon (SOC). While numerous studies have shown that DRS can produce accurate and precise estimates of SOC across landscapes, whether DRS can detect subtle management induced changes in SOC at a given site has not been resolved. Here, we leverage archived soil samples from seven long-term research trials in the U.S. to test this question using mid infrared (MIR) spectroscopy coupled with the USDA-NRCS Kellogg Soil Survey Laboratory MIR spectral library. Overall, MIR-based estimates of SOC%, with samples scanned on a secondary instrument, were excellent with the root mean square error ranging from 0.10 to 0.33% across the seven sites. In all but two instances, the same statistically significant (p < 0.10) management effect was found using both the lab-based SOC% and MIR estimated SOC% data. Despite some additional uncertainty, primarily in the form of bias, these results suggest that large existing MIR spectral libraries can be operationalized in other laboratories for successful carbon monitoring.more » « less
-
{"Abstract":["Interactions between plants and soil microbes influence plant\n nutrient transformations, including nitrogen (N) fixation, nutrient\n mineralization, and resource exchanges through fungal networks.\n Physical disturbances to soils can disrupt soil microbes and\n associated processes that support plant and microbial productivity.\n In low resource drylands, biological soil crusts\n ("biocrusts") occupy surface soils and house key\n autotrophic and diazotrophic bacteria, non-vascular plants, or\n lichens. Interactions among biocrusts, plants, and fungal networks\n between them are hypothesized to drive carbon and nutrient dynamics;\n however, comparisons across ecosystems are needed to generalize how\n soil disturbances alter microbial communities and their\n contributions to N pools and transformations. To evaluate linkages\n among plants, fungi, and biocrusts, we disturbed all unvegetated\n surfaces with human foot trampling twice yearly in dry conditions\n from 2013-2018 in cyanobacteria-dominated biocrusts in Chihuahuan\n Desert grassland and shrubland ecosystems. Our study included\n microbial communities and N pools sampled at different time points\n in the disturbance treatments at one or both sites. We began our\n sampling after observations in April 2018 that the chlorophyll a\n content was at least double in control than disturbed plots in both\n ecosystems (Chung et al. 2019). Stomping occurred in May, and we\n collected soil and plant samples in June 2018 for N pools and soil\n and root fungal abundance. We collected additional soil samples in\n September 2018 and conducted the 15N tracer experiment to observe\n rates of N transfer from biocrust to plants before the fall stomp\n treatment in October. We collected chlorophyll a samples and soils\n for sequencing bacteria in September of 2019, also before the fall\n stomp treatment."]}more » « less
