Cascading effects of grazing on predatory arthropod and parasitoid densities

An important goal in arthropod conservation is to understand how arthropods are affected by anthropogenic activities. Livestock graze 29% of the land area in the U.S., which can result in both top-down and bottom-up effects on ecosystems that are grazed. Grazing often reduces species richness and abundance of arthropods; however, these trends depend upon context and taxa, making generalization difficult. Grazing can either increase or decrease species richness and abundance of arthropods, depending on context and taxa, making generalization difficult. The impacts of grazing on different taxa may also be indirect, depending upon trophic interactions with other members of the community. We propose that considering trophic relationships will help clarify the effects of grazing on arthropods. Here, we study the effects of grazing by ungulates on pompilid wasps (Hemipepsis and Pepsis hawk wasps) and tarantulas (Aphonopelma hentzi). We do this by comparing the cover of forbs (flowering plants..., We sampled forb cover, wasp densities, and tarantula densities at five shortgrass prairie sites in southeastern Colorado, USA (Cook & Redente, 1993, Figure 1a), which has a semi-arid, continental climate with hot summers and cold winters. Hardy, drought-resistant grasses dominate most of the region, which is commonly used for cattle grazing. For example, in 2019 was recorded as supporting 452,400 cattle on 27 million acres (Meyer, 2019).  
Our sites were located on Southern Plains Land Trust property, which manages the grazing levels there. Domestic cattle grazed three of the sites at moderate to heavy levels (one head per 30 acres or 0.082 head/hectare, year-round). The remaining two lightly grazed sites were not stocked with cattle and only grazed by deer (Odocoileus spp.), pronghorn (Antilocapra americana), occasional elk (Cervus canadensis), and, rarely, escaped cattle. Wild cervids occurred in grazed sites as well. Because most of the region is grazed, only two lightly gra..., , # Cascading effects of grazing on predatory arthropod and parasitoid densities

[https://doi.org/10.5061/dryad.mpg4f4r9g](https://doi.org/10.5061/dryad.mpg4f4r9g)

## Description of the data and file structure

**Overview**

This dataset contains ecological sampling data collected in southeastern Colorado, USA, across five shortgrass prairie sites managed by the Southern Plains Land Trust. The data focuses on assessing the relationship between grazing levels and the densities of tarantulas, hawk wasps (Hemipepsis and Pepsis), and forb cover, providing valuable insights into the effects of grazing on shortgrass prairie ecosystems.

The shortgrass prairie in this region experiences a semi-arid continental climate, characterized by hot summers and cold winters. The vegetation is dominated by drought-resistant grasses, making it ideal for cattle grazing. Sampling was conducted between 2021 and 2022 as part of an ecological study.

**Study Sites and Grazing Levels**

* **Grazed Sites**: Thre...,