Platte River Whooping Crane Maintenance Trust (Crane Trust) Supra-database V2
Description
This dataset summarizes the results of 386 vegetation surveys and relevant land management actions conducted over 11 growing seasons from 2015 through 2025. Surveys were conducted at 74 long-term vegetation monitoring plots in terrestrial habitats within the Central Platte River Valley of Nebraska, which are owned and/or managed by the Crane Trust. Survey areas consisted of upland and lowland herbaceous and woody habitats including wet meadows, prairies, woodlands, shrublands, and savannas. Additionally, monitoring sites have a range of land use histories. “Relict” sites have never been tilled and largely retain their historic character, with vegetation dominated by native species. “Rehabilitated” sites were also never tilled but were historically degraded through neglect or overuse, losing many native species and/or shifting to an alternative stable state (e.g., meadow to woodland). These sites have since been actively managed to recover their historic character, such as by reversing woody encroachment or controlling invasive species. “Reconstructed” sites were once tilled for row crops but have been reseeded with native prairie species believed to have historically occurred in the region and have also often been recontoured to reflect historic topography before industrial agriculture. Survey sites were visited between 1 and 9 times each and 5.22 times over 11 growing seasons on average (SD = 2.03, SE = 0.2). Woodland sites were only surveyed during our initial inventory efforts unless later management or restoration activities (e.g., prescribed fire) occurred, as woodland habitats generally laid outside of the Crane Trust’s rotationally managed pastures under routine monitoring. Monitoring of all other terrestrial habitats (i.e., meadows, prairies, etc.) occurred on an every-other-year (i.e., biennial) cycle. However, when necessary, survey plots were visited more frequently to assess the initial response to significant woody or invasive species control efforts. Overall, woodland sites were surveyed an average of 2.0 times (range = 1-3) while all other habitats were surveyed 5.6 times (range = 1-9) over 11 growing seasons. Finally, monitoring plots were progressively added along with the conservation of additional properties; therefore, some sites were surveyed less simply because they were established more recently. The dataset provides a great deal of information for each monitoring plot including plant species richness, dominance, and cover metrics per site visit disaggregated plant growth habit as well as several standard indices for site assessment including the floristic quality index, the mean wetland indicator status, and the Simpson diversity index. Finally, the dataset also provides key management data such grazing and controlled burning metrics. Version 2 has been updated to fix formatting errors, remove excess data rows, and add data missing from Version 1.
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The sampling design and survey methods used to collect vegetation data within riparian habitats along the Platte River were previously described in detail by Caven et al. (2017), Caven and Wiese (2022), and Caven et al. (2022). We established a vegetation inventory and monitoring system using an ecotope-based design, where sampling units were defined by unique combinations of soil type, flooding frequency, land-use history, and vegetation community. Ecotopes represent the smallest practical landscape unit for analysis, being both mappable and homogeneous considering biotic (e.g., plant cover) and abiotic (e.g., hydrology, soils) features. Soil and hydrology information was derived from USDA–NRCS (2021) data, while land-use history and vegetation characteristics were compiled from organizational records, previous publications, and aerial imagery (e.g., Nagel 1981). To capture the diversity of conditions across the landscape, we used a stratified random sampling approach that placed multiple plots within each distinct ecotope type. These monitoring plots are roughly distributed across 6,500 ac (2,630 ha). To assess plant community composition and structure, two complementary field survey techniques were employed across study sites: the line-point intercept method and the quadrat-based ocular cover estimation. The line-point intercept method effectively documents dominant vegetation, structural, and ground cover characteristics, but is less sensitive to variations in species richness. Observations were made every 2 meters along permanently marked 100-meter transects, with species recorded across three vertical strata: low (<0.5 m), mid (0.5–2.0 m), and upper (>2.0 m). Ground cover was categorized broadly into litter/duff and bare soil/rock. Species richness and relative abundance were visual estimated using a quadrat ocular cover estimation method, which involved placing a 0.5 × 1.0 m quadrat placed every 10 meters along the survey transect and visually estimating of percent cover of each species detected within the sampling frame to the nearest 5%. Overlapping canopies were accounted for, often resulting in total cover values exceeding 100%. This method is more effective at detecting rarer species. Surveys were conducted during the frost-free growing season, typically between mid-June and mid-October, when plants were mature enough for accurate identification. Most vegetation was identified to species level, with a small proportion classified to genus.