DOI: 10.5061/dryad.51c59zw8j
title: Scale dependence in functional equivalence and difference in the soil microbiome

description: Climatic history can shape the functioning of soil microbial communities
 and thus rates of ecosystem processes such as organic matter
 decomposition. For example, broad spatial scale differences in climatic
 history, such as contrasting precipitation regimes, have been shown to
 generate unique microbial functional responses to contemporary moisture
 conditions. Yet it is an open question as to whether local differences in
 soil microclimate similarly influence the functional potential of
 decomposer communities. Here, we use a multi-scale approach within and
 among two temperate forest field sites to investigate this question. Soils
 from fifty-four microsites, that vary in their soil moisture
 climate-regimes, were used as inocula for a common leaf litter (Quercus
 rubra) in a controlled, laboratory microcosm study. Microcosms were placed
 under dry, mesic and wet lab-moisture conditions and the rate of carbon
 (C) mineralization of the litter was measured over 202 days. Our results
 reveal differences in decomposition rates under controlled conditions that
 highlight broad-scale functional differences between the soil communities
 at each site. Specifically, we found that C mineralization differed by as
 much as two-fold for soil communities when compared between the sites. Our
 results also show that functional differences of soil communities are
 observable within one site but not the other. In the site where
 local-scale functional legacies were apparent, the historical soil
 moisture microclimate-regimes generated as much as an 89% change in C
 mineralization rates of the leaf litter under the same contemporary,
 lab-imposed moisture conditions. A similar pattern was not observable in
 the other site; instead, laboratory moisture conditions explained almost
 all variation in C mineralization. Our findings confirm those from prior
 studies where regional-scale moisture-regime differences shape microbial
 function, and extends this prior work by providing evidence that
 pronounced local-scale differences in soil moisture microclimate-regimes
 can generate microbial functional legacies.
description: Full methods can be found in the associated manuscript.
 Briefly, twenty-seven 1 m<sup>2</sup> plots within
 each of two forest sites (SCBI: Smithsonian Conservation Biological
 Institute, Front Royal, VA and HARV: Harvard Forest, Petersham, MA) were
 set up in fall 2019. Soil measurements (temperature, moisture, pH, etc)
 were taken over a 10-month period from December 2019 to September
 2020. Soils from these plots were used to inoculate
 <em>Quercus rubra</em> leaf litter in a lab microcosm
 experiment across different moisture treatments. Carbon mineralization was
 measured over 202 days by measuring CO<sub>2</sub> production
 in each microcosm over 24 h at 17 time points (day 1, 6, 9, 13, 20, 27,
 34, 43, 50, 64, 78, 92, 105, 120, 141, 168, 202) with the frequency of
 measurement decreasing over the course of the experiment. Cumulative C
 mineralization rates were calculated. To estimate
 CO<sub>2</sub> evolved from <em>Q. rubra</em>
 litter, cumulative C mineralization from litter-soil microcosms were
 subtracted from soil-only controls for the corresponding microsite soil
 sample.
description: There are 4 associated CSVs in this dataset:
 1. Micosite properties that describe the microsite by elevation,
 associated tree species, tree DBH, slope, and aspect.
 microsite_properties.csv 2. microsite
 measurements that include site, plot, date sampled, sampling period name,
 soil temperature, litter temperature, soil gravimetric water content, soil
 pH, microbial biomass (SIR), soil %N, soil %C, soil C:N, bulk density
 (0-5cm), soil water holding capcity
 microsite_measurements.csv 3. microcosm
 experiment carbon mineralization time series that includes site, plot,
 lab.id, microcosm.id, replicate, day, date, lab treament, litter carbon
 mineralization, soil carbon mineralization
 cMineralization.csv 4. cumulative carbon
 mineralization from 202 day microcosm experiment that includes site, plot,
 treatment, replicate, litter cumulative carbon mineralization, and soil
 umulative carbon mineralization
 cumulative_CMineralization.csv  
 There is one README file that describes the variables and units
 within each CSV.
 PolussaetalScaleDependenceREADME.txt