TW006

This database was developed to store data for ecophysiology and ecohydrology studies in Watershed 01 (WS01) at the H.J. Andrews Experimental Forest. The data include a combination of continuous sensor measurements (e.g. for soil moisture, soil temperature, air temperature, and relative humidity data) and repeated sampling (e.g., litterfall, dissolved organic carbon (DOC), rock content of soils).

WS01 was clear cut between 1962 and 1966, burned, and replanted to varying degrees of success with Pseudotsuga menziesii, and a set of long-term plots that lie on transects normal to the main stream system was installed in 1962 to monitor plant succession and biomass development (TP073). The plots for these ecohydrological studies were co-located with a subset of TP073 plots to facilitate cross-referencing and cross-analysis of information. The boundaries of the TW006 plots are all at least 5 meters outside of the boundaries of the plant succession and biomass plots so as not to interfere with the long term integrity of those plots.

An initial set of eight plots were installed for TW006 in 2004. All of these plots were located near transect #1 of the TP073 plots; i.e. the transect closest to the mouth of the watershed (see http://oregonstate.edu/feel/mapsVideos/transect_diagram.jpg, http://oregonstate.edu/feel/mapsVideos/airshed_base.pdf, and for a “virtual tour” of the watershed that illustrates the plot locations see http://oregonstate.edu/feel/mapsVideos/WS01_3d_spinningWheel2.AVI.MOV). Each of the eight plots (also known as “telemetry plots”) is associated with a bank of solar collectors and batteries that provide power for a network of sensors, and data is transmitted by telemetry via a relay station to the Andrews Headquarters. An additional set of 16 plots was established in 2009 to extend data collection through a broader area of the watershed and to represent the full range of vegetation cover classes. The locations of these was based on a stratified random sampling of TP073 plots. Data from the 2009 LiDAR reconnaissance were used to do this. A LiDAR “cover*height” index was assigned to each of the TP073 plots, and the plots were then grouped into five “height*cover” categories. Three plots were randomly selected from the lowest two categories, two from the highest category, and four each from the remaining categories. In some cases it was necessary to re-select because the randomly-selected plots were relatively inaccessible, so the final set of plots may be somewhat biased on the basis of access for sampling. The figure below shows the location of the 16 plots relative to the network of TP073 permanent plots with background colors showing the LiDAR “height*cover” classes.

All of the 16 plots were used for litterfall collections between 2009-2011. Litter was collected with sets of 5 traps per plot with 43 cm x 43 cm dimensions per plot. The traps were initially installed on August 12. 2009. Collections began in October, 2009 and continued at monthly intervals during the summer and bi-monthly intervals during the winter for two years. In 2010, a soil pit of 30 cm x 30 cm x 30 cm was dug near one of the litter traps for each of the plots and all of the rocks within these pits were excavated, bagged and returned to Dr. Kate Lajtha’s laboratory where they were cleaned, dried and weighed to estimate soil rock content. Initial analysis of these data suggested that the sample size was too small to adequately represent the range of productivity in the watershed, so four additional plots were added. The plots were further excavated in July and August of 2010 to install two lysimeters (3 inch long, 1 inch diameter remote suction) at a depth of 70-90 cm.

Starting in November, 2010, lysimeters were evaculated with a hand pump, and between 1 and 7 days later, any water collected in the lysimeters was collected into a vial and returned to the laboratory for analysis of dissolved organic carbon (DOC). Sampling continued at irregular intervals thereafter.