DOI: 10.5061/dryad.7sqv9s52c
title: Data in: Reduced predation and energy flux in soil food webs by introduced tree species

description: The introduction of non-native tree species has become a global concern
 and may disrupt native communities and related ecosystem functions. Soil
 food webs regulate organic matter decomposition and nutrient cycling in
 forests with their feeding activities, but evaluating the consequences of
 tree species introduction on soil invertebrates is challenging due to the
 complex trophic structure and wide range in body size of soil
 invertebrates. Here, we employed an energetic food web approach and
 estimated the energy flux in soil food webs using a four-node model
 including soil meso- and macrofauna decomposers and predators. We examined
 pure and mixed stands of native European beech (Fagus sylvatica),
 introduced Douglas fir (Pseudotsuga menziesii), and native range-expanding
 Norway spruce (Picea abies) across site conditions. Compared to native
 forests, introduced tree species reduced the total mass of macrofauna
 predators by 92% at sandy sites but not that of decomposers, suggesting
 trophic downgrading in soil food webs by Douglas fir. The energy flux in
 mixed forests was intermediate between respective monocultures, suggesting
 that tree mixtures mitigate potential negative impacts of introduced tree
 species on food web functioning. Across size classes, soil macrofauna
 responded more sensitively to changes in environmental conditions than
 soil mesofauna. Despite the lower total mass, the energy flux through
 mesofauna outweighed that through macrofauna when considering energy loss
 to predators, highlighting the importance of mesofauna for decomposition
 processes in forest soil food webs. Additionally, total energy flux
 positively correlated with species richness, pointing to the significance
 of soil biodiversity for trophic functionality. Overall, the study
 emphasizes the critical role of tree species composition, site conditions,
 and soil biodiversity in driving energy flux through soil food webs and
 maintaining forest ecosystem functions.
description: Soil samples were taken to evaluate the population density of
 soil meso- and macrofauna between November 2017 and January 2018. At an
 equidistance from trees of the same (pure stands) or different species
 (mixed stands), two small (⌀ 5 cm) and two large (⌀ 20 cm) soil cores were
 taken at a distance of approximately 10 m close to the center of each
 plot. Soil cores were separated into litter (OL/F), 0–5 cm, and 5–10 cm
 depth and transported to the laboratory for extraction of soil meso- and
 macrofauna using heat. Mesofauna (Acari, Collembola, Diplura, Pauropoda,
 Protura, Symphyla) were extracted from small cores, and Pseudoscorpionida
 and macrofauna were extracted from large cores. The extracted animals were
 collected in 50% diethylene glycol and then transferred into 70% ethanol
 for determination. Animal taxa were first sorted and
 assigned into functional groups. Adults of soil microarthropods
 (Collembola, Mesostigmata, and Oribatida) were identified to species
 level, and other soil invertebrates were identified to taxonomic levels
 sufficient for functional guild assignment using a stereomicroscope and a
 microscope. In particular, Coleoptera were identified to families,
 including juveniles, allowing trophic assignment to predators or
 decomposers. Species diversity was estimated based on one soil core for
 soil Collembola, Mesostigmata, and Oribatida, and two soil cores for
 Pseudoscorpionida and macrofauna (Araneae, Coleoptera, Isopoda, Myriapoda,
 Opiliones, Wenglein<sup> </sup>et al. in preparation).
 Decomposer groups included Collembola, Diplopoda, Diplura, Elateridae,
 Isopoda, Lumbricidae, Oribatida, Pauropoda, Protura, Scarabaeidae, and
 Symphyla; predator groups included Araneae, Cantharidae, Carabidae,
 Chilopoda, Coccinellidae, Dermestidae, Mesostigmata, Opiliones,
 Pseudoscorpionida, and Staphylinidae. For
 microarthropods, species-specific body sizes were used to estimate their
 fresh mass. Exceptions were juveniles of Oribatida and Mesostigmata, which
 were grouped into size classes. Different allometric equations were used
 for adults and juveniles of mites, because no species key exists for mite
 juveniles, and only body length was estimated. Individual body size of
 other animal groups was measured from one soil core in each plot using a
 camera system (Zeiss Stemi 2000-CS with Zeiss AxioCam ICc1). Where there
 were more than ten individuals present in each morphospecies, ten
 individuals were randomly selected for body size measurements. Individual
 biomass was estimated from body size using group-specific power equations
 based on either body length or both length and width (Table S2).
 Individual metabolic rate was estimated based on group-specific allometric
 scaling equations, using mean annual air temperature in each plot. Total
 fresh mass and community metabolism were summed up from
 individual-estimated data and used for energy flux models. 
description: # Data in Reduced predation and energy flux in soil food webs by
 introduced tree species
 [https://doi.org/10.5061/dryad.7sqv9s52c](https://doi.org/10.5061/dryad.7sqv9s52c) ## Description of the data and file structure The data include fresh mass, energy flux, and local biodiversity of soil mesofauna (decomposer, predator) and macrofauna (decomposer, predator).   ### Files and variables #### File: \_Lu2024-Biomass_and_energy_flux_in_temperate_forests.csv **Description:**  ##### Variables * id_forest: 1 to 5 coding for forest type (Douglas, Douglas-Beech, Beech, Spruce-Beech, Spruce) * id_quintet: one of the eight study sites (1-8) * Q_groups: quintet groups, Q1-4 (loamy sites), Q5-8 (sandy sites) * mass_macrodecomposer: fresh mass in ug m-2 of macrofauna decomposer * mass_mesodecomposer: fresh mass in ug  m-2 * mass_macropredator: fresh mass in ug  m-2 * mass_mesopredator: fresh mass in ug  m-2 * mass_total: fresh mass in ug m-2 * flux_macrodecomposer: energy flux in Joule m-2 h-1 of macrofauna decomposer * flux_mesodecomposer: energy flux in Joule m-2 h-1 * flux_macropredator: energy flux in Joule m-2 h-1 * flux_mesopredator: energy flux in Joule m-2 h-1 * flux_total: energy flux in Joule m-2 h-1 * richness_macrodecomposer: species number per plot of macrofauna decomposer * richness_mesodecomposer: species number per plot of mesofauna decomposer * richness_macropredator: species number per plot * richness_mesopredator: species number per plot * richness_total: species number per plot ## Access information Data was derived from the following sources: * [https://doi.org/10.1594/PANGAEA.944647](https://doi.org/10.1594/PANGAEA.944647) * [https://doi.org/10.1594/PANGAEA.944669](https://doi.org/10.1594/PANGAEA.944669) * [https://doi.org/10.1594/PANGAEA.944676](https://doi.org/10.1594/PANGAEA.944676)