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Data from: Insectivorous birds and bats outperform ants in the top-down regulation of arthropods across strata of a Japanese temperate forest

Cite this dataset

Sivault, Elise et al. (2024). Data from: Insectivorous birds and bats outperform ants in the top-down regulation of arthropods across strata of a Japanese temperate forest [Dataset]. Dryad. https://doi.org/10.5061/dryad.xpnvx0kq2

Abstract

Birds, bats, and ants are recognized as significant arthropod predators. However, empirical studies reveal inconsistent trends in their relative roles in top-down control across strata. Here, we describe the differences between forest strata in the separate effects of birds, bats, and ants on arthropod densities and their cascading effects on plant damage. We implemented a factorial design to exclude vertebrates and ants in both the canopy and understory. Additionally, we separately excluded birds and bats from the understory using diurnal and nocturnal exclosures. At the end of the experiments, we collected all arthropods and assessed herbivory damage. Arthropods responded similarly to predator exclusion across forest strata, with a density increase of 81% on trees without vertebrates and 53% without both vertebrates and ants. Additionally, bird exclusion alone led to an 89% increase in arthropod density, while bat exclusion resulted in a 63% increase. Herbivory increased by 42% when vertebrates were excluded and by 35% when both vertebrates and ants were excluded. Bird exclusion alone increased herbivory damage by 28%, while the exclusion of bats showed a detectable but non-significant increase (by 22%). In contrast, ant exclusion had no significant effect on arthropod density or herbivory damage across strata. Our results reveal that the effects of birds and bats on arthropod density and herbivory damage are similar between the forest canopy and understory in this temperate forest. In addition, ants were not found to be significant predators in our system. Furthermore, birds, bats, and ants appeared to exhibit antagonistic relationships in influencing arthropod density. These findings highlight, unprecedentedly, the equal importance of birds and bats in maintaining ecological balance across different strata of a temperate forest.

README: Insectivorous birds and bats outperform ants in the top-down regulation of arthropods across strata of a Japanese temperate forest

https://doi.org/10.5061/dryad.xpnvx0kq2

Here are the two main important datasets used throughout the manuscript.

Arthropod_dataset.xlsx shows the total arthropod density per sample found in our study as well as the densities partionned into four feeding guilds: NR, Sapsuckers, Herbivores and Predators.

Herbivory_datatset.xlsx presents the herbivory estimations found for each twig in our study.

Description of Arthropod_dataset.xlsx

PlantSpeciesAnal : Tree species 

Strata : Stratum where the arthropods were collected to measure herbivory (Understory or Canopy)

Patrol : Season of Collection (A or B)

Treatment : Name of each treatment (ALL, ANT, CN2, CN3, BIR, BAT, CN1)

Total.arth : Total number of collected arthropods 

Herb : Number of collected herbivorous arthropods

NR : Number of collected NR arthropods (Arthropods with No Relationships with herbivory or other predators) 

Pred : Number of collected Predatory arthropods

Sap : Number of collected sapsucking arthropods

TotalLeafArea : Mean area of the leaves (cm²)

Tot.ab.f : Total density of arthropods (abundance of arthropods / mean leaf area)

Tot.ab.herb : Density of herbivorous arthropods

Tot.ab.NR : Density of NR arthropods

Tot.ab.Pred : Density of predatory arthropods

Tot.ab.sap : Density of sapsucking arthropods

Description of Herbivory_dataset.xlsx

Strata : Stratum where the leaves were collected to measure herbivory (Understory or Canopy)

Treatment: Name of each treatment (ALL, ANT, CN2, CN3, BIR, BAT, CN1)

Experiment : Name of the experiment (CUVA, UBB or CN3)

Patrol : Season of Collection (A or B)

HerbProp : Herbivory estimation (proportions)

Twig : Color of the twig of the selected branch

SpeciesAnal : Tree species

Methods

We collected this dataset in the Tomakomai experimental forest in Hokkaido, Japan. 

We conducted two parallel experiments with different purposes. The Canopy-Understory Vertebrate and Ant Exclusion (CUVA) experiment focused on predator effects (ants, vertebrates, and their combination) on arthropod densities and herbivory in the forest understory and canopy, while the Understory Bird and Bat Exclusion (UBB) experiment specifically examined the individual effects of birds and bats in the understory. Additionally, we complemented our research on the impact of predators on arthropods and plants by conducting surveys of the excluded predator communities. Each experiment was conducted twice: first in 2018 and then replicated in 2019. 

Funding

European Research Council, Award: 805189, Starting grant

University of South Bohemia in České Budějovice, Award: 014/2022/P, Grant agency

Cooperation activity with , Award: VAJVA-19-65