Riparian vegetation data used for comparing sampling methods along the Colorado River, Grand Canyon, Arizona
Data for journal manuscript: A comparison of riparian vegetation sampling methods along a large, regulated river
Dates
Publication Date
2019-05-14
Time Period
2019
Citation
Palmquist, E.C., 2019, Riparian vegetation data used for comparing sampling methods along the Colorado River, Grand Canyon, Arizona: U.S. Geological Survey data release, https://doi.org/10.5066/P9N2RBIC.
Summary
These data were collected as part of a methodologial comparison for collecting riparian vegetation data. Two common methods for collecting vegetation data were used: line-point intercept and 1m2 ocular quadrats (visual cover estimates). At each site and transect, both methods were used to collect cover and composition data by four different observers. The same transects and quadrats were utilized for both methods and all observers. Field data collected included percent cover for total living foliar cover, each plant species encountered, litter, dead plant material that is still standing, and ground cover features (biological soil crust, rock, sand, and fine soil particles). Line-point intercept data were collected at 25 cm intervals [...]
Summary
These data were collected as part of a methodologial comparison for collecting riparian vegetation data. Two common methods for collecting vegetation data were used: line-point intercept and 1m2 ocular quadrats (visual cover estimates). At each site and transect, both methods were used to collect cover and composition data by four different observers. The same transects and quadrats were utilized for both methods and all observers. Field data collected included percent cover for total living foliar cover, each plant species encountered, litter, dead plant material that is still standing, and ground cover features (biological soil crust, rock, sand, and fine soil particles). Line-point intercept data were collected at 25 cm intervals along each transect and at four points along the edge of each 1m2 quadrat. Since transects varied in length, the number of data points collected along each transect also varied. A pin flag was dropped vertically to the ground at 25 cm intervals and every plant species and ground cover element that touched the pin flag was recorded in the order it touched the pin flag from top to bottom, including any species that would touch the pin flag if it continued upward indefinitely. Each species was only recorded once at each point. Ocular quadrat data were collected at each of the 1 m2 quadrats. Cover estimates were recorded to the nearest 5% other than those estimates under 5% which were recorded as either 1% or “trace”. Observers calibrated their ocular estimates at the beginning of sampling and when a new observer started sampling. Observers were given reference cards illustrating multiple levels of percent cover (1 – 95%), which were used during calibration and throughout data collection. Five observers with three levels of experience participated in this study. Two observers had extensive experience with identification of plant species in the study area, as well as with the methods used. One observer was familiar with the methods as well as riparian plant identification, but had not previously worked in this study area. Two observers had not worked in this system or with these methods before, but had experience conducting vegetation surveys. All observers received on-site training. At each site, four observers sampled the entire site using both field methods.
The purpose of this data was to compare vegetation sampling methods in a dense, species rich riparian context to 1) assess if ocular or LPI sampling methods result in significant differences in cover among observers, 2) identify if the ocular or LPI sampling method has lower variability among observers, 3) assess which method best records the high diversity of riparian areas, and 4) examine how the cover estimates generated from these methods differ.
Rights
The author(s) of these data request that data users contact them regarding intended use and to assist with understanding limitations and interpretation. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
