Objectives: The aims of this research are to (i) use dendrochronological techniques to assess the performance of B. papyrifera to intra- and inter-annual microclimatic variability and (ii) determine if satellite imagery can serve as a proxy for assessing tree health by relating vegetation indices such as NDVI to tree-ring characteristics.
Principal Investigator: Tala Awada, Paolo Cherubini
Recommended Citation: Awada T., Bumann E., and Cherubini P., 2016 "Betula papyrifera tree cores from Niobrara river, NE"
Project Contents: Data for 1 Plot, 45 Trees, 155 Cores
Project Period: 0000-00-00 to 0000-00-00
Data License: Data is available upon request What's this?
Description: Remnant populations of Betula papyrifera have persisted in the Great Plains after the Wisconsin Glaciation along the Niobrara River Valley, Nebraska. Population health has declined in recent years, which has been hypothesized to be due to climate change. We used tree rings to assess the response of B. papyrifera to microclimate and the normalized difference vegetation index (NDVI) derived from satellite imagery as a proxy for population health. The study area was located at the Nature Conservancy’s Niobrara Valley Preserve in north-central Nebraska, centered at 42°78′34″N, 100°02′80″W, and encompasses nearly 227 km2. Seven north-facing stands were selected along a 27 km section of the river. Individuals were found only on north-facing slopes and growing from pre-existing root crowns. We selected the largest trees based on healthiest visual appearance and largest diameter measured at breast height. A total of 180 cores, i.e., four cores from each of 45 trees, were sampled at 1.3 m from the base, at 90° around the trunk, representing the north, south, east, and west sides. The oldest ring record dated back to 1894, with the majority of consistent records across trees rings dating back to the early 1950s, thus the time frame selected for this study.
Related Publications: No related publications
Taxonomic standard used: USDA Plants Database
How plots were selected: Sites were located at the Nature Conservancy in the Niobrara River Valley. Sites were identified visually by canoe and accessed through the river.
How trees were selected: Trees within sites were selected based on their condition and stem diameter. We selected the largest stems.
Exclusion of trees (if any): Trees less than 10cm DBH were rejected. Trees that appeared to have trunk rot (determined by crown condition) were rejected.
How cores were collected: Four increment cores were collected from the selected stems at 1.3m from the root crown, at 90 degree intervals around the trunk; representing the north, south, east, and west facing orientations.
How cores were processed: Cores were placed in plastic core trays and were air dried for several weeks. Once dried, cores were glued to wooden dowels and sanded flat and smoothed with up to 600 grit sandpaper. Cores were analyzed at the University of Nebraska-Lincoln and the Dendrochronology laboratory, Swiss Federal Institute for Forests, Snow and Landscapes, WSL, Switzerland.
North and east increment cores were processed at UNL were scanned at 3200 dpi and individual ring widths were measured to the nearest 0.01 mm using WinDENDRO. South and west increment cores were measured under a microscope to the nearest 0.01 mm using a linear table at the Dendrochronology lab in Switzerland“LINTAB”. The data were recorded, presented, and analyzed in TSAPWin. After visually cross-dating each tree core (north, south, east, and west), each sample plot was visually cross-dated in TSAPWin. Missing rings were inserted manually with a value of 0 to complete the chronology. The visually cross-dated data were imported into CONFECHA for statistical analysis to check cross-dating accuracy. Additionally, we determined the “Gleichläufigkeit” (Glk), which is a measure of the year-to-year agreement between the interval trends of two chronologies based upon the sign of agreement and usually expressed as a percentage of cases of agreement, as well as the cross-dating index (CDI), which is a combination of the Glk and the t value of the chronology. Crossdating software used: TSAPWin, COFECHA
Exclusion of cores (if any): Increment cores that lacked structural integrity due to wet rot were rejected, ultimately resulting in 153 of 180 increment cores from a total of 43 of 45 trees.
Added to the database: 10/18/2021
Last modified: 03/24/2022