PE EIE[R-Rg RESEARCH ON - HJ Andrews Experimental Forest

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Proceedings-Research on Coniferous <strong>Forest</strong> Ecosystems-A symposium . Bellingham, Washington-March 23-24, 197 2 The lysimeter installation on the Cedar River Watershed Leo J . Fritsche n Associate Professo r College of <strong>Forest</strong> Resource s University of Washingto n Seattle, Washingto n Abstract A lysimeter was built around the root ball of a 28 m Douglas-fir (Pseudotsuga menziesii) tree. The container , tree, and soil weigh 28,900 kg. The sensitivity of the weighing mechanism is 630g which is equivalent t o 0.06 mm of water. The installation will be used to study evapotranspiration and volume changes in relation t o soil water potential and atmospheric demand; to test cuvette and meteorological methods ; determine canop y interception ; and to assess the effects of irrigation and fertilization . Introduction Understanding the process and quantifying the rate of water transfer within a forest ecosystem has become increasingly more important in recent years . This concern has originated from both applied and basic directions . For example, it has been estimated that by 1980, six major regions will have no wate r reserve. These regions are Colorado River , South Pacific, Great Basin, Upper Ri o Grande, Pecos River, and Upper Missour i River (Colorado River Association 1966) . Furthermore, interbasin transfer is bein g practiced in at least two areas at the presen t time . Increasing need for water conservation, th e possibility of interbasin water transfer, and the treatment of watersheds to increase yiel d or change quality has demonstrated the nee d for additional research on water use by various types of vegetative cover. For example , clearcutting a north-facing Coweeta watershe d resulted in a 1st year increase streamflow o f 40.2 cm and a stabilized increase of 23 .8 cm . Although the 1st year 's increase from a south - facing watershed was only 15 cm which de - creased to insignificance by the 3d year (Swift, unpublished data), it is believed that the different microclimatic influences upon the vegetation and resulting evapotranspiration will account for the discrepancy in wate r yield. To understand fully the processes involved and to predict results from futur e cuttings require detailed investigations relating water use to its availability and to atmospheric conditions . Short-period (1 hour or less) determinations of evapotranspiration are necessary t o study the complex soil-plant-atmospheric relations. Many methods or combination o f methods have been employed to determin e evapotranspiration. The major ones includ e watershed runoff ; measurement of soi l moisture depletion by either gravimetri c sampling, with resistance blocks, or with neutron soil moisture meters ; use of weighin g lysimeters ; and application of meteorologica l models . Other methods have employe d percolation tension plates, stemflow measurements, and enclosures . Of these methods only weighing lysimeters, enclosures, and meteorological models are capable of yielding hourl y results . Enclosures alter the microclimate an d 255
may bias the results . Meteorological method s must be tested in the areas of anticipated us e (Slatyer and Mcllroy 1961) . Such testing has not been accomplished in forested areas . Thus, weighing lysimetry appears to be th e only method capable of yielding the neede d short period accurate rates . Weighing lysimeters have been used to determine evapotranspiration of agriculture crops (McIlroy and Angus 1963, Pruitt and Angus 1960, Harrold and Dreibelbis 1951, Va n Bavel and Meyers 1962), but they haven't been used for natural vegetation, such a s brush and trees, which have extensive root systems . The use of weighing lysimeters to deter - mine evapotranspiration of trees is feasibl e only if the trees are uniformly spaced such as in a plantation . Installation is easier when the root system is naturally restricted, thereby reducing the size of the lysimeter and it s deadweight. Under these conditions, it would be possible to obtain accurate short period evapotranspiration rates, thus enabling a mechanistic examination of evapotranspiration in relation to the determining meteorological and soil moisture conditions . Establishment of evapotranspiration from a single tree or group of trees in a specific location is important but does not yield answer s for other types of vegetation in different climatic zones . Installation of lysimeters in many locations is not possible and may not be feasible because of the cost . However, meteorological methods if tested can be employed to establish evapotranspiration rates wher e lysimeters are not feasible. Results fro m meteorological methods can be tested against the results from a properly installed weighing lysimeter. This has been accomplished for agriculture crops (Tanner 1967, Pruitt 1963 , Fritschen and Van Bavel 1963, Fritsche n 1965) . However, differences in scale factor s such as canopy height, density, and roughnes s demand additional testing before these methods can be used over natural vegetation . The purpose of this paper is to discuss th e establishment of the weighing lysimeter in a Douglas-fir forest for the primary purpose of studying the complex relation between evapotranspiration rates and the determining meteorological and soil moisture conditions . In later stages the installation will be used t o evaluate meteorological methods for determining evapotranspiration to be used i n other areas . The Site The lysimeter installation is located on the Cedar River Watershed near Seattle, Washing - ton. The soil is a Barneston, gravelly, loamy sand originating from glacial outwash laid down at the end of the Vashon glacial period (Poulson and Miller 1952) and generally restricts the root system above the 3-foot depth (Gessel and Cole 1965) . The lateral extent of the root system is largely restricted to th e basic spacing of the trees . The area is relatively level and has a uniform canopy density making it desirable for micrometeorological investigations . The trees are 35-year-old Douglas-fir (Pseudotsuga menziesii) which regenerated naturally after logging. The average tree spacing i s 5.8 m, resulting in 231 trees per 4,041 m 2 consisting mostly of Douglas-fir with a fe w hemlock (Tsuga heterophylla) and maple . Trees in the 5 to 30 cm d.b.h. classes occur with the greatest frequency . Ground vegetation consists of bracken fern (Pteridiu m aquilinum), salal (Gaultheria shallon), red huckleberry (Vaccinium parvifolium), an d mosses, mainly (Eurhynchium oregonum) . The Lysimeter The lysimeter was constructed around th e root ball of a 35-year-old, 28 m tall an d 38 cm diameter Douglas-fir tree . The lysimeter consists of two right cylinder containers, one located within the other . The inner - most container in which the tree is located i s 366 cm in diameter and 122 cm deep, havin g a surface area of 10 .5 m 2 (fig. 1). The container at "field capacity " with tree and soi l weighs 28,900 kg (fig . 2) . The inner container is resting on a hydraulic transducer located on the bottom of th e outer container. The hydraulic transduce r consists of eleven 15 m lengths of 6 .35 c m 256
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PE EIE[R-Rg RESEARC H O N CONIFEROU
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Research on Coniferous Forest Ecosy
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Contents SOME BROADER VIEWS OF BIOM
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Page AQUATIC PROCESS STUDIES 279 St
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Proceedings-Research on Coniferous
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directly, to solution of major natu
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4. Nutritional adaptation to enviro
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where validation studies could be c
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have been developed . Prior to thei
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of gross production and respiration
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Figure 1 . Aerial photo of Findley
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Nutrient levels in stream and lake
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Acknowledgments The work reported i
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inputs into the lakes . Recent stud
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was slightly raised in 1902, the la
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climate, surrounding terrestrial en
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more similar than between the diffe
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The net rate of primary production
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community structure and energy flo
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est adapted organism vacillates bet
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U .S . Analysis of Ecosystems, Inte
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successful . Thus we can see modeli
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of the external quantities of S wou
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Figure 2 . The major subsystems of
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subsystems as objects . In addition
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several models together to form the
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The study areas are located at seve
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K m Figure 1 . Watershed 2, H . J.
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An alternative way of considering i
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Snowmelt A flow chart of the snow a
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d Gs Gr = (1 - Ki) d t By integrati
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Calibration of Parameter s In gener
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model being developed under the Con
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Usually, we are interested in the o
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LINEAR Y~(T) 2nd ORDER Y2 (T) 3rd O
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the watershed. The hydrologic model
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considered as part of another food
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PRIMARY PRRODUCTIO N ■ FOLIAGE CO
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Graham, S. A. 1952. Forest entomolo
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ful in regions with relatively unif
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epresents the basic linkages betwee
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Cleary and Waring 1969, Reed 1971,
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vation that species such as Brewer
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Table 3.-Predicted plant response i
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Walker, Reed, Scott, and Webb are c
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Water and Nutrien t Movement Throug
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Here v is the volume of water cross
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2 10 7100 .160 .220 .280 .340 .400
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.0500 .040 0 z .030 0 E L.) 0 .020
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ment of the flux of ions through th
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Table 2 .-Forest floor composition
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Table 5 .-Monthly amounts of litter
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Figure 2 illustrates how CO 2 produ
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Ballard, T. M. 1968 . Carbon dioxid
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2. How effectively are these chemic
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Table 2 .-Nutrient budget for disso
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Figure 1 . Water content of the sur
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0.12_ _30 rn z 0 Q z w 0 z 0 0 z Q
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_3 0 . Outflow Concentration _ __ R
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0.10_ 0.08 _ Pea k 0.04_ Concentrat
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8J Calciu m 0 I I I I 0.25 0.50 0.7
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water is dominant because flowing w
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Table 1.-Characteristics of study p
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Z w 2 w J w 3 0 Table 2. Average to
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of the nitrogen was not determined.
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Table 6. Total kg per hectare per y
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through litterfall . More amounts o
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Figure 3. Two additional carabiners
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1 1 Figure 11 . The climber places
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Figure 16. The spar in use. The sus
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in our example) and the running tot
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Dashed lines are dead branches . Th
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Table 1.-Transpiration rates, mean
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this case the slopes of activity-ti
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solve equation 2 for Tm since the f
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ing methods . Every point in the sa
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Patterns in Point Displacemen t Mea
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trees indicates that the coordinate
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data; there is no obvious explanati
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where C is the percentage cover by
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Table 1.-Epiphyte biomass on the tr
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NZ. 4 50 100 150 EPIPHYTE IMPORTANC
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Table 4.-Biomass estimates (kg) for
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watershed 10 (C . T. Dyrness, perso
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Table 1 .-Some population character
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Table 2 .-Annual litter fall in Col
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Table 4. Biomass and growth increme
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Table 6.-Annual turnover from certa
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Kiil, A. D. 1968. Weight of the fue
Page 195 and 196: condition differ) ; the turnover ra
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Page 199 and 200: Bird Studies The forest birds were
Page 201 and 202: Further Studies The data provided f
Page 203 and 204: Terrestrial Process Studies 209
Page 205 and 206: from theses. The principal processe
Page 207 and 208: Table 1 .-Saturating light intensit
Page 209 and 210: at least 0 .06 percent CO 2 . Howev
Page 211 and 212: Pharis et al. 1967). Again Helms (1
Page 213 and 214: Effects of Leaf Temperature an d Le
Page 215 and 216: Literature Cited Baule, H., and C.
Page 217 and 218: Lopushinsky, W . 1969. Stomatal clo
Page 219 and 220: Proceedings-Research on Coniferous
Page 221 and 222: Von Bertalanffy (1969) calls nonsum
Page 223 and 224: which may be of importance in model
Page 225 and 226: The first three terms of equation 1
Page 227 and 228: P = F+ R where F = net assimilation
Page 231 and 232: This function is asymptotic to zero
Page 233 and 234: The important interaction between l
Page 237 and 238: (3 = H/AE=yo$/De (3 ) where y is th
Page 239 and 240: 0.4 0.2 v 0 0 w IX -0.2 I- cr -0.4
Page 241 and 242: Table L-Diurnal energy budget compo
Page 243 and 244: 4 8 10 12 14 16 18 20 22 24 TIME, H
Page 245: 1970. Evapotranspiration an d meteo
Page 249 and 250: 7.4 ppm . The lysimeters at Coshoct
Page 251 and 252: Acknowledgments The work reported i
Page 253 and 254: extracted was determined by the wei
Page 257 and 258: I - 5 -l o -1 5 HPV 1 10 . 0 I . 6
Page 259 and 260: Table 1 .- Tukey's w Multiple Compa
Page 261 and 262: studies in conifers-a review . In J
Page 263 and 264: permeable to both CO 2 and water va
Page 265 and 266: insolation (1 cal cm 2 min-1 ) and
Page 267 and 268: Aquatic Process Studies 279
Page 269 and 270: stream environments (Krygier and Ha
Page 271 and 272: S, - 4ydrolo9i c S2 = I¢rr¢strIa
Page 273 and 274: ingestion variation between individ
Page 277 and 278: contribute to detrital compartment
Page 279 and 280: volume measurement, realizing that
Page 281 and 282: fer of the indicated carbon-14 trac
Page 283 and 284: 18L LAKE WATER LIGH T 50m1 HOURLY D
Page 285 and 286: a function of time and space, (b) c
Page 289 and 290: Table 1.-Suggested criteria for jud
Page 291 and 292: Table 4.-Average C, N, and P conten
Page 293 and 294: during 1963 to 1967 and from Lake S
Page 295 and 296: greater than 7 .2:1 (16:1 by atoms)
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2 .0 1 .0 0 Si P-N N-Si P-Si P-N-Si
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detectable increase in concentratio
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in lakes . J. Ecol . 29 : 280-329 .
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Woodey 1970 ; Thorne, Reeves, and M
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targets are insonified several time
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This program will automatically cal
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The FOREST SERVICE et ; U :' S D pa
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