AvalonPosterFinal

AvalonPosterFinal

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  Author: Leslie Goldman ©2013 National Ecological Observatory Network, Inc. All rights reserved. The National Ecological Observatory Network is a project sponsored by the National Science Foundation and managed under cooperative agreement by NEON, Inc. This material is based upon work supported by the National Science Foundation under the following grants: EF-1029808, EF-1138160, EF-1150319 and DBI-0752017. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Plant communities famously vary in their allocation of carbon resources to aboveground shoots and belowground roots; the balance of which has an outstanding role in carbon sequestration and nutrient cycling within ecosystems. Much literature and research has been allocated to understanding and mapping aboveground shoots, however there is a lack of literature on belowground roots especially on a large scale. Many studies are dedicated to understanding rooting systems of specific plant communities; however the purpose of this study is to continentally model fine root biomass. Fine root biomass was collected by the National Ecological Observatory Network from 35 sites across the United States. Climate, pedological, and ecological factors were then used to create a predictive model of β. Where β is the non-linear least squares fit of the cumulative fine root proportion at depth. β was best predicted by the climate ratio and NLCD class, however failed to be modeled at sites with extreme climate types, such as those of high aridity. Abstract Contact Information: [email protected] www.neoninc.org  NLCD Class and Climate Ratio are the best predictive factors for modeling β.  Two models with different variable factors may be needed to create a separate model for the sites under extreme climate ratios. However those with climate ratios between (0.3-1.5) may be modeled using simplified NLCD class and climate ratio. Here ae some highlights about the diagram above: • Bullet 1 • Bullet 2 • Bullet 3 LAYOUT NOTES: Don’t forget to use the Paragraph palette to manage line spacing; and turn on your rulers to adjust your indents for the bullet text… Climatic and Ecological Factors Explain Fine Root Biomass at Depth on the Continental Scale Author: Avalon Hoek Spaans (Junior, University of Florida), Cody Flagg(Mentor), Katie LeVan(Mentor), Alison Hogeboom, Jennifer C. Everhart, Courtney Meier, Julia J. Spencer Modeling Fine Root Proportion at Depth Future Directions • Investigate using a more accurate ecological predictor instead of NLCD class, which accounts for age and density of vegetation. • Explore the relationship between soil physical /chemical properties and belowground biomass in deep soil profiles  Clay content  C:N ratio  % N • Create a predictive model which focuses on sites sampled under extreme climate types. References: Gale, M.R., D.K. Grigal, 1987. Vertical root distributions of northern tree species in relation to successional status. Can J For Res 17:829-834. Gill, R., R. Kelly, W. J. Parton, K. Day, R. Jackson, J. a Morgan, J. M. O. Scurlock, L. L. Tieszen, J. V Castle, D. S. Ojima, and X. S. Zhang. 2002. Using simple environmental variables to estimate below- ground productivity in grasslands. Global Ecology and Biogeography 11:79–86. Spencer, J., C. . Meier, H. Abercrombie, and J. . Everhart. 2013. Belowground Biomass Sampling to Estimate Fine Root Mass across NEON Sites. Continental Scale Sampling Belowground Biomass Sampling Methods Conclusions Soil Pits Sampled as of July 2015 Fig. 1: 35 soil pits have been sampled across 15 ecoclimatic domains as of July 2015, with 60 sites to be completed by 2017. Fig. 2: Field technicians collect belowground biomass for each profile (outlined in blue) in D05TREE. Prediction of Beta under Extreme Climate Types Fine Root Proportion at Depth In each panel(right), lower ß values indicate shallower rooting profiles, while higher ß values indicate deeper rooting profiles. The ß value is the non-linear least squares fit for ß using the equation Y=1-ßd (Gale and Grigal, 1987) where Y is the cumulative root proportion, d = depth from the soil surface, and ß is the fitted parameter. (Jackson et al., 1996). Data from 27 out of the 35 sites with complete pedological, climatic, and ecological data were then used to create a predictive model of Beta. Climatic variables included: mean annual temperature, mean annual precipitation, and climate ratio. Pedological variables included: total coarse fragments, soil texture, average porosity, and bulk density. The ecological variable that was used was NLCD class (land use cover). Models were tested in multiple variable combinations with ecological, climatic, and pedological factors of a single variable, two variables, or three variables. 62 models were tested resulting in NLCD class and Climate Ratio (Mean Annual Precipitation/Potential Evapotranspiration) as the best predictors. Modeling Beta with Climatic and Ecological Factors a) How well can ß be predicted? The actual ß values from each soil pit are plotted against the predicted ß values(left) for 27 sites where complete data were available. The model took ß as a function of two independent state factors: Climate Ratio, and simplified NLCD classes, where the adjusted R2= 0.45. b) NLCD Class influence on prediction of ß NLCD categories of land use vary in their influence on β, with forest and wetland sites indicating a deeper rooting profile than herbaceous sites. c) Climate influence on the prediction of ß Climate Ratio negatively influences Beta, where sites with great aridity (lower climate ratio) indicate a deeper rooting profile.  Soil samples of a known volume were taken from three vertical profiles down the face at 10 cm intervals down to 1m and at 20cm intervals from 1 m to the final pit depth of 2m.  Samples were then wet sieved to extract root mass, and categorized based on coarse, fine, live, and dead characteristics.  Where fine roots (<2mm) and coarse roots (>2mm)  Roots were then dried at 65°C for 48 hours and weighed.  This study will focus only on fine live and dead roots, as many of the sites that were sampled contained no coarse roots.  Each pit (2m deep and approximately 1.5m wide) was dug adjacent to the NEON Observation Tower  Every site undergoes a standardized collection of belowground biomass, and soil physical and chemical properties.  The soil pit root sampling effort allows estimation of the proportion of roots sampled at a given depth, and generates a baseline estimate for belowground biomass distributions with depth across all NEON sites. Figure 5: Climate Ratio and NLCD were used to model Beta at 33 sites with complete ecological and climatic data. The adjusted R2 decreased from 0.45 to 0.18, this can be seen due primarily to the addition of sites with extreme climate ratios, with an increase in arid sites from the desert southwest (D13MOAB, D14SRER, D14JORN, D15ONAQ), and the addition of a humid continental climate site (D16ABBY). Fig 3: The cumulative root proportion as a function of soil depth for 35 NEON sites. Fig 4: Influential factors of the best predictive model of β.