NPP Temperate Forest: OTTER Project Sites, Oregon, U.S.A., 1989-1991


[PHOTOGRAPH]
Photograph: Forest in the western coastal range of Oregon (click on the photo to view a series of images from the OTTER sites)

Data Citation

Cite this data set as follows:

Waring, R. H., B. Law, and B. Bond. 1999. NPP Temperate Forest: OTTER Project Sites, Oregon, U.S.A., 1989-1991. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

Description

The Oregon Transect Ecosystem Research Project (OTTER) was conducted to develop a strategy to extrapolate point measurements and estimates of ecosystem structure and function across large geographic regions that varied in climate and vegetation. The full spectrum of remote-sensing data and algorithms were evaluated for their satisfaction of parameter requirements of ecosystem models to assess ecosystem structure and function. Ground-based field and laboratory measurements were used to initialize, drive, and validate the predictions of the model and of remote-sensing analysis. The goal was to be able to predict the major fluxes of carbon, nitrogen, water, and the factors that regulate the dynamics of these variables. Full details and access to other data from this project are available through the OTTER pages maintained by the ORNL DAAC. The OTTER NPP Data Set, described here, contains only the estimates of NPP and associated measurements from the OTTER transect that were made during the period 1989-1991.

The study region was a transect which began near Cascade Head Experimental Forest, north of Lincoln City, Oregon (44.95 N 124.02 W) and extended approximately 250 km to Redmond (44.27 N 121.17 W), located in the high desert interior of Oregon. The transect included six forest ecosystem sites selected from the same forest community types as an earlier study of biomass, leaf area, and NPP by Dr. H. L. Gholz (1976-1977). Together, these study sites displayed almost the complete range of net primary productivity found in North America: from the western-most site going east, the site names are Cascade Head, Waring's Woods, Scio, Santiam Pass, Metolius, and Juniper. Three plots -- control ("Gholz's site"), nitrogen-enriched (alder), and old-growth -- were studied at the Cascade Head site with Tsuga heterophylla dominating the control and old-growth plots and Alnus rubra dominating the nitrogen-enriched plot. The Waring's Woods and Santiam Pass sites received no treatment and were dominated by Pseudotsuga menziesii and Tsuga mertensiana, respectively. The Scio site had three plots -- control, single fertilization, and double fertilization -- all of which were dominated by Pseudotsuga menziesii and Tsuga heterophylla. Pinus ponderosa dominated the two plots, control and fertilized, at the Metolius site. The Juniper site, which received no treatment, was dominated by Juniperus occidentalis. The treatment plots or subsidiary stands were also studied because nitrogen is known to be lacking in this region.

Mean annual temperature varied inversely with elevation, from 11.2 C (170 m) at Waring's Woods to 6.0 C (1460 m) at Santiam Pass. Annual precipitation ranged from 220 mm at the eastern-most site to 2510 mm at the coastal sites but did not vary linearly across the intervening sites.

Net primary productivity (above- and below-ground; NPP), estimated from ground-based measurements, for the Cascade Head (old-growth), Cascade Head (alder), Waring's Woods, Scio (control), Scio (single fertilization), Santiam Pass, Metolius (control), Metolius (fertilized), and Juniper sites was 1360, 1630, 1540, 2250, 2570, 750, 320, 320, and 300 g/m2/yr, respectively. Estimated below-ground NPP increased from 20% to 60% with increasing harshness of the environment. Although the sites intercepted between 22% to 99.5% of the incident photosynthetically active radiation, the amount they were able to utilize varied from 92% in the coastal rainforests to <25% in the juniper woodland as a result of temperature extremes, drought, and vapor pressure deficit extremes. Comparisons of NPP predictions made by the FOREST-BGC model to the measured data resulted in an r-squared of 0.82. The remotely sensed data (from broad- and narrow-spectral-band instruments) were capable of providing estimates of leaf area index that could be used in forest ecosystem simulation models to estimate evapotranspiration, photosynthesis, canopy turnover, and net primary productivity over large areas. Remote sensing also provided values for nitrogen content, lignin concentration, chlorophyll, and intercepted photosynthetically active radiation (IPAR). While the extraction of important ecological and environmental information from satellite remotely sensed observations was possible, it was made difficult by atmospheric attenuation and residual cloud cover.

Some imagery from the OTTER study sites is publicly available from the Earth Observations Laboratory/ Institute for Space and Terrestrial Science in Ontario, Canada. Dr. R. H. Waring, Dr. B. E. Law and Dr. H. L. Gholz have also provided further notes explaining the range of estimates of LAI and how mean "modelable" values were arrived at by Dr. L. L. Pierce and co-workers.

References (some with summaries) to the OTTER data set and some applications of the data are available.

Main Reference

Runyon, J., R. H. Waring, S. N. Goward, and J. M. Welles. 1994. Environmental limits on net primary production and light-use efficiency across the Oregon transect. Ecological Applications 4: 226-237. (Other papers describing the OTTER project results may be found in this special issue of Ecological Applications [Volume 4, part 2]).

Contact Information

Contacts: Dr. Beverly Law and Dr. Barbara Bond
Department of Forest Science
Oregon State University
Corvallis
Oregon 97331-7501
U.S.A.

E-mail: lawb@fsl.orst.edu / barbara.bond@orst.edu