Nutrient and stoichiometric time series measurements of decomposing coarse detritus in freshwaters

Abstract

Decomposition of coarse detritus (e.g., dead organic matter larger than ~1 mm such as leaf litter or animal carcasses) in freshwater ecosystems is well described in terms of mass loss, particularly as rates that compress mass loss into one number (e.g., a first‐order decay coefficient, or breakdown rate, “k”); less described are temporal changes in the elemental composition of these materials during decomposition, with important implications for elemental cycling from microbes to ecosystems. This stands in contrast with work in the terrestrial realm, where a focus on detrital elemental cycling has provided a sharper mechanistic understanding of decomposition, especially with specific processes such as immobilization and mineralization. Notably, freshwater ecologists often measure carbon (C), nitrogen (N), and phosphorus (P), and their stoichiometric ratios in decomposing coarse materials, including carcasses, wood, leaf litter, and more, but these measurements remain piecemeal. These detrital nutrients are measurements of the entire detrital–microbial complex and are integrative of numerous processes, especially nutrient immobilization and mineralization, and associated microbial growth and death. Thus, data relevant to an elemental, mechanistically focused decomposition ecology are available in freshwaters, but have not been fully applied to that purpose. We synthesized published detrital nutrient and stoichiometry measurements at a global scale, yielding 4038 observations comprising 810 decomposition time series (i.e., measurements within a defined cohort of decomposing material through time) to build a basis for understanding the temporality of elemental content in freshwater detritus. Specifically, the dataset focuses on temporally and ontogenetically (mass loss) explicit measurements of N, P, and stoichiometry (C:N, C:P, N:P). We also collected ancillary data, including detrital characteristics (e.g., species, lignin content), water physiochemistry, geographic location, incubation system type, and methodological variables (e.g., bag mesh size). These measurements are important to unlocking mechanistic insights into detrital ontogeny (the temporal trajectory of decomposing materials) that can provide a deeper understanding of heterotroph‐driven C and nutrient cycling in freshwaters. Moreover, these data can help to bridge aquatic and terrestrial decomposition ecology, across plant or animal origin. By focusing on temporal trajectories of elements, this dataset facilitates cross‐ecosystem comparisons of fundamental decomposition controls on elemental fluxes. It provides a strong starting point (e.g., via modeling efforts) for comparing processes such as immobilization and mineralization that are understudied in freshwaters. Time series from decomposing leaf litter, particularly in streams, are common in the dataset, but we also synthesized ontogenies of animal‐based detritus, which tend to decompose rapidly compared with plant‐based detritus that contains high concentrations of structural compounds su...

Nutrient and stoichiometry dynamics of decomposing litter in stream ecosystems: A global synthesis

“…Further detail can be accessed in a detailed protocol for data extraction and validation (Appendix S2: Sections S1 and S2). The data set is archived with the Environmental Data Initiative (Robbins et al, 2022) and the data sources used specifically for analyses in this study are referenced in Appendix S2: Section S3.…”

“…We synthesized a data set of temporal trends in detrital nutrients (N and P) and stoichiometry (C:N, C:P, N:P) by completing a literature search in Academic Search Complete, Agricola, and Web of Science using queries specified in Appendix S1: Section S1. The synthesized data set (Robbins et al, 2022) is archived with the Environmental Data Initiative at https://doi.org/10.6073/pasta/f53d35244db9a38da0cd7d2e37503270. The code (Robbins, 2023) used to generate the analysis and presentations in this manuscript is archived with Zenodo at https://doi.org/10.5281/zenodo.7770607.…”

Reading tea leaves worldwide: Decoupled drivers of initial litter decomposition mass‐loss rate and stabilization

“…These include a measurement-based interpolation map in addition to equivalents to litter production from five well-accepted land surface models (CABLE, ISAM, JULES, OCN and ORCHIDEE) at a resolution of 1800 arcsec (0.5°). To account for the variation of litter quality, we took the median (0.72), upper quartile (0.80) and lower quartile (0.61) hydrolysable fraction from 145 plant species (Own measurements; Harmon, 2016;Robbins et al, 2022, see Figure S7). This proved a robust representation of the variation in litter quality and spanned the same range as the (unequally represented) growth forms (Figure S7).…”

Reasons to not correct for leaching in TBI; Reply to Lind et al. (2022)

“…In aquatic systems, leaching as an initial event is possible to quantify (Elwood et al, 1981;Gessner et al, 1999;Seelen et al, 2019). However, in these systems, the duration of leaching measurements is also unstandardised (although frequently 24 h) and correcting mass losses for leaching is relatively uncommon (Benfield et al, 2017;Robbins et al, 2022).…”