Data from: Mastication treatments increase perennial herbaceous cover across soil types in southeastern Colorado piñon-juniper woodlands

Description

In this study we assessed vegetation responses to mastication treatments across three dominant soil types in two-needle piñon (Pinus edulis Engelm. [Pinaceae]) - one-seed juniper (Juniperus monosperma [Engelm.] Sarg.) woodlands in southeast Colorado, USA – a region characterized by monsoonal precipitation, limited presence of introduced plant species, and relatively high grazing intensity by cattle and wildlife. We surveyed understory species composition in the year prior to mastication (2018) as well as 1 (2019) and 3 years (2021) post-mastication. Fifteen sites were established, with paired treatment and control plots that measured 10 by 50 meters. The line point intercept method was used to survey ground cover and plant community composition across all years. Targeted sampling of understory plants also occurred in small quadrats in 2019 and 2021 under where canopy trees existed prior to mastication, on the edge of the tree canopy prior to mastication, and in the interspace.

Steps to reproduce

Sampling was conducted between late July and early August of 2018 (pre-treatment), 2019 (1-year post-treatment), and 2021 (3-years post-treatment). Pre-treatment vegetation sampling was conducted to establish baseline assessments of groundcover, plant community composition, and woodland structure in both control and treated plots. At each plot we established a 50-m transect in the center of the plot that ran south to north. We used the line point intercept method to characterize ground cover and plant community composition, which was done by dropping a pin flag from chest height at each meter and recording all plants intercepted from top to bottom and the ground cover (biological soil crust, bare soil, rock, plant litter, wood, mulch, or plant base). We identified plants to the species level when possible and recorded their status (live or dead). To assess woodland structure, we recorded the diameter at root collar (DRC), canopy area, species, height, and location along the transect of all trees in the 50 m x 10 m plot that were greater than 1 m in height. Due to relatively low tree cover across the study area (8% mean cover across plots pre-treatment [2018]), we conducted targeted sampling of understory vegetation beneath and adjacent to trees (or where trees were previously located in the masticated plots) to assess the effects of mastication treatments one (2019) and three (2021) years after mastication. To do this, we established six 0.25-m2 quadrats directly beneath and adjacent to three trees (or mulch piles where trees previously existed for masticated plots) in each plot. Trees were selected by sampling the closest tree to the 0-m, 25-m, and 50-m points along the transect. Quadrats were then established at three microsites on the north and south side of the tree bole: directly beneath tree canopies (referred to as “under”), along the canopy edge (“edge”), and two meters beyond the edge of the tree canopy (“inter”). In each quadrat we recorded percent cover of all plant species rooted within the quadrat using ocular estimates, with a maximum of 100% cover per quadrat. Percent cover values were summarized by taking the average across all trees (n = 3) and cardinal directions (north, south) for each microsite (under, edge, inter) in each plot. These values were then used to estimate plant diversity, richness, and cover by species and functional group in each microsite type in each plot.

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