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Do dense layers of invasive plants elevate the foraging intensity of small mammals in temperate deciduous forests? A case study from Pennsylvania, USA

Citation

Utz, Ryan M.; Slater, Alysha; Rosche, Hannah R.; Carson, Walter P. (2020), Do dense layers of invasive plants elevate the foraging intensity of small mammals in temperate deciduous forests? A case study from Pennsylvania, USA, Dryad, Dataset, https://doi.org/10.5061/dryad.w3r2280nb

Abstract

Monospecific stands of invasive plants can dramatically restructure habitat for fauna, thereby elevating population densities or promoting foraging of consumer species who benefit in the altered habitat. For example, dense stands of invasive plants may protect small mammals from predators, which in turn could increase foraging pressure on seeds that small mammals feed upon. We used a before-after, control-impact experimental design to test whether small mammal capture rates were higher and giving-up densities (GUDs) lower beneath dense stands of Berberis thunbergii, an invasive shrub with a rapidly expanding range throughout eastern North America. Our experimental design included three plot categories: 1) plots heavily invaded by B. thunbergii, 2) control plots lacking invasive shrub cover, and 3) invaded plots where we eradicated B. thunbergii midway through the study. Although our overall small mammal capture rate was low, small mammal captures were 65% higher in B. thunbergii invaded habitat relative to control plots and eradication lowered capture rates by 77%. GUDs were also 26% higher within B. thunbergii relative to control plots and eradication decreased GUDs by 65%. Our findings suggest that small mammals perceive dense stands of B. thunbergii as relatively safe foraging habitat. Prior surveys within our study locations revealed dramatically depressed tree seedling densities under B. thunbergii, thus invasive plants may promote intensive foraging by small mammals and reduce recruitment for species with foraged seeds or seedlings.

Usage Notes

Data usage notes for NeoBiota article: Do dense layers of invasive plants elevate the foraging intensity of small mammals in temperate deciduous forests? A case study from Pennsylvania, USA

Three datasets are provided:

  1. small mammal live trap data (Trap Data.csv),
  2. small mammal seed tray data (Seed Tray Data.csv), and
  3. vegetation surveys (Vegetation data.csv).

The data dictionary below defines all parameters in the datasets.

Trap data.csv 

Site.ID: unique site identifier for each site. EH=Eden Hall site, LT=Latodami, IR=Irwin Run
Trap.Condition: E=empty, T=thrown, D=damaged or destroyed, M=mammal present in trap
Weather: qualitative weather descriptor
Mammal: the genus and species of mammal collected in trap
Sex: the sex of the specimen
Mass: the mass of the small mammal, when present, in grams
Ticks: whether or not ticks were observed on small mammal
D_deploy: date when the trap was set
D_collect: date when the trap was collected
Remove_status: whether the date represents a period before barberry removal (B) or after (A)

Seed data.csv

Site.ID: unique site identifier for each site. EH=Eden Hall site, LT=Latodami, IR=Irwin Run
Deploy.date: date when the trap was set
Collect.date: date when the trap was collected
Tray.intact: whether or not the tray was found intact after the deployment period
Feces: if small mammal feces were present in trays
Tracks: if small mammal tracks were present in trays
Seed.mass: remaining seed mass, in grams; 6 grams were initially deployed
Remove_status: whether the date represents a period before barberry removal (B) or after (A)

Vegetation data.csv 

This dataset represents the two square meter vegetation surveys conducted at each site. Blank cells represent NA values for the sub-survey square meter. Each row represents 1 or 2 individual plants encountered in the sub-survey.

Site.ID: unique site identifier for each site. EH=Eden Hall site, LT=Latodami, IR=Irwin Run
survey.1: barberry stem diameters for all stems encountered in the first square meter survey
survey.2: barberry stem diameters for all stems encountered in the second square meter survey
dry.mass.1: estimated dry mass of the corresponding barberry plant in the first sub-survey based on allometric equation in Link et al. 2018
dry.mass.2: estimated dry mass of the corresponding barberry plant in the second sub-survey based on allometric equation in Link et al. 2018