Patterns of root biomass, productivity, turnover, and decomposition in riverine mangroves in the Everglades, Florida, USA, post-Irma, 2018-2019

Patterns of root biomass, productivity, turnover, and decomposition in riverine mangroves in the Everglades, Florida, USA, post-Irma, 2018-2019: Mangrove root biomass, productivity, and decomposition in the shallow (0-45 cm depth) root zone were estimated at Florida Coastal Everglades Long Term Ecological Research (FCE-LTER) Program Shark River (SRS4, SRS5, SRS6, SRS7) mangrove sites during 2018-2019 following Hurricane Irma’s impacts. Root biomass was estimated at all sites in March 2018 with a PVC coring device (10.2 cm diameter x 45 cm length) using the same sampling protocol previously published for the study area (Castañeda-Moya et al. 2011). After collection, root cores were processed individually and initially rinsed with water through a 1-mm screen mesh to remove soil particles. Live roots were separated manually based on their buoyancy, turgor, and color (Castañeda-Moya et al. 2011; Cormier et al. 2015; Medina-Calderon et al. 2021). Live roots were further sorted into three size diameter classes including fine (<2 mm), small (2-5 mm), and coarse (5-20 mm). Roots greater than 20 mm in diameter were not included in this study due to sampling limitations (i.e., core area). All root samples were oven-dried at 60°C to a constant mass and weighed to estimate root biomass (g m-2). Root productivity was estimated with the ingrowth core technique (Vogt et al., 1998) using the same sampling protocol previously published for the study area (Castañeda-Moya et al. 2011). Ingrowth cores (10.2 cm diameter x 45 cm length) were made of synthetic material (3 mm mesh) and filled with root-free commercial sphagnum peat moss. This material has similar soil properties (i.e., bulk density, organic matter content, total C and N) as mangrove peat in our study sites. Ingrowth cores were installed in each of the cored holes formed during sampling of root biomass. At each site, ingrowth cores were deployed vertically into the soil to a depth of 45 cm and retrieved one year later (March 2019). Root growth within the ingrowth core was used to estimate annual root production (g m-2 yr-1) in the shallow root zone across all mangrove sites. After collection, ingrowth cores were processed individually using the same protocol as for root biomass. Turnover rate of fine roots in the shallow root zone was calculated as root productivity divided by root biomass at all sites. Root decomposition experiments were initiated in January 2018 at each site using the mesh bag (1-mm2; 10 x 40 cm) technique. Live roots were initially extracted by coring, rinsed with water to remove soil particles, air-dried for 24 hours, and then placed inside bags. Mesh bags were divided into two 20-cm depth sections (0-20 cm, 20-40 cm), each one containing 5-6 g of fresh root material from each site with an equal mixture of three root size classes: 1-4, 4-8, and 8-12 mm. A total of 18 bags were buried in the soil within two sampling points at each site. Bags were retrieved from sampling points after 190, 358, and 541 days of incubation, oven-dried at 60°C to a constant mass and weighed to estimate root mass loss. Decay rates of mangrove roots were calculated for all sites using the negative exponential model, Mt = M0 e-kt, where Mt = the percentage of dry root mass remaining at time t, M0 = original dry root mass, and k = decay constant (Nye 1961; Olson 1963). Data collection for this package is complete. See also, related pre-Irma root data (https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-fce&identifier=1277). References: Medina-Calderon, J.H., J.E. Mancera-Pineda, E. Castañeda-Moya, and V.H. Rivera-Monroy. 2021. Hydroperiod and salinity interactions control mangrove root dynamics in a karstic oceanic island in the Caribbean Sea (San Andres, Colombia). Frontiers in Marine Science 7: 598132. https://doi.org/10.3389/fmars.2020.598132. Cormier, N., R.R. Twilley, C.K. Ewel, and K.W. Krauss. 2015. Fine root productivity varies along nitrogen and phosphorus gradients in high-rainfall mangrove forests of Micronesia. Hydrobiologia 750, 69-87. Castañeda-Moya, E., R.R. Twilley, V.H. Rivera-Monroy, B.D. Marx, C. Coronado-Molina, and S.M.L. Ewe. 2011. Patterns of root dynamics in mangrove forests along environmental gradients in the Florida Coastal Everglades, USA. Ecosystems 14: 1178-1195. https://doi.org/10.1007/s10021-011-9473-3. Vogt, K.A., D.J. Vogt, J. Bloomfield. 1998. Analysis of some direct and indirect methods for estimating root biomass and production of forests at an ecosystem level. Plant Soil 200:71–89. Olson, J. S. 1963. Energy storage and the balance of producers and decomposers in ecological systems. Ecology 44: 322-331 Nye, P. H. 1961. Organic matter and nutrient cycles under moist tropical forest. Plant and Soil 13: 333-346.