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

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the basic energy budget model given in equation 2 . The gradients of temperature an d vapor above the rough, porous forest canop y are very slight, and measurement difficultie s increase with small gradients . Another major problem is related to the difficulty of measuring changes in stored energy in the biomass of the forest . These problems will be placed int o perspective at the Cedar River site, for the y affect the analyses and the subsequent interpretation of the results . Evaluation of Gradients Gradients of temperature, vapor concentration, and wind are small above fores t canopies, even though the transfer of energy and mass may be proceeding at high rates . The small gradients result from mixing induced by the mechanical turbulence create d by the rough canopy surface . In addition, the exchange surfaces are distributed through a considerable canopy depth so that the source s of heat and vapor are diffuse, rather tha n being concentrated as in the dense canopies of crops or other low vegetation . The smal l gradients above the forest require tha t extreme care be taken in the development o f suitable instrumentation, and in the experimental design controlling the deployment o f sensors . The Bowen ratio model assumed tha t steady state conditions prevail, i .e., the value s of the variables do not change with respect t o time during the period of analysis . This i s partially satisfied by averaging the values ove r the period of an hour before applying the model . Integration into hourly means als o reduces the small random component of error associated with the measurements. It does not, however, reduce biases that are introduced by small differences among sensors . Such biases can be a source of serious error , particularly with small gradients that exis t above the forest . Bias errors must be handle d by techniques other than averaging . Two approaches have been used to cope with the problems involved in the measurement of small gradients above forests . In the first approach, the two levels of measuremen t required for the Bowen ratio are separated by a relatively large distance (10 m) in order to increase the differences that are being measured to a level commensurate with the sensitivity of the data system (Galoux et al . 1967 , Storr et al. 1970) . In the second, reversing sensors have been used to cancel the effect of any small biases that may exist between sensors (Black and McNaughton 1971) . A large vertical separation of the sensors introduces questions of the representativenes s of the measured gradients which should represent the effect of the underlying surface . It is quite possible that a sensor placed 10 m abov e the canopy may be measuring properties o f the atmosphere that are derived from a surface other than the one under investigation . In contrast, a pair of reversing sensors, place d near the canopy, offers an excellent means fo r evaluating small gradients . However, the reversing mechanism introduces new problem s of design for operation and support in tal l forests . A graphical approach was used in this study to minimize sensor errors in the gradien t measurements used for the Bowen ratio analysis . Initially, the mean hourly values o f potential temperature were plotted agains t the associated values of vapor pressure t o yield 24 plots (1 per hour) for each day, with each plot containing six points (one for eac h measurement level) . The plots will be straigh t lines if similarity exists between the gradient s of potential temperature and vapor concentration, providing there are no errors of measurement (Tanner 1963). Since similarity is an assumption of the Bowen ratio method, thes e plots were used to separate out the instrument levels that exhibited small offset s throughout the day and to identify thos e levels appropriate for use in the Bowen rati o analysis . The similarity plots for July 29 are shown for levels 1, 4, 6 in figure IA, and for levels 1 , 2, 3 on July 31 in figure 1B . The potentia l temperature (e-) scale on the ordinate differ s between the 2 days. The vapor pressure (e ) scale is shown in the legend . Note that the plo t for each hour has been normalized by subtracting the & and e value at the bottom level fro m the observations at each of the other levels . Therefore each plot actually shows the incre - 246
0.4 0.2 v 0 0 w IX -0.2 I- cr -0.4 w -0.6 ~ 0.04 A ..29 JULY HOUR (PDT) -->- y y g i 0 I 2 3 4 5 6 7 1I I 1 1! I r 17 .19 202122 23 2 4 9 10 II 12 13 14 15 16 o 18 B. 31 JULY r a I 2 3 4 5 6 7 8 9 HOUR (PDT)----4 .- 10 I I 2.03.122! J 1213 14 15 16 17 18 19 ° 1 23 24 0- I u -0.04 • MB VAPOR PRESSURE, M B Figure 1 . Similarity between gradients of potential temperature and vapor pressure . A. Clear weather on Jul y 29, 1971 . Levels 1, 4, and 6 . B . Overcast weather on July 31, 1971 . Levels 1, 2, and 3 . ment of a and e with respect to the firs t measurement level near the canopy . Though several points can be deduced fro m such similarity plots, the most important conclusion concerns adequacy of data . The linearity at the selected levels confirms their acceptability for the Bowen ratio model , although an unexplained offset is evident at level 2 during the 1000-1200 hours on Jul y 31 . Once the data is judged acceptable, on e notes that the slope of the lines is A&/Ae ; this is directly proportional to 0, the Bowen ratio , as shown in equation 3 . Thus the relative slope of the similarity plots is an index to th e way that the surface is partitioning the net energy supply into convection and evaporation. Further, the quadrant of each hourl y plot indicates the sign of 0, and the direction of the H and XE fluxes . For example, as plotted in figure 1A and 1B, both fluxes will have the same sense in quadrants I and III where the slope is positiv e ((3>0). In quadrant I, H and XE are both directed away from the surface and are negative by the sign convention adopted earlier . In quadrant III, H and XE are both positive, a s their sense is toward the surface . The slop e and the (3 coefficient are negative in quadrant s II and IV. In quadrant II, H is toward th e surface (advection) while XE is directed away , while the fluxes in quadrant IV have th e opposite sense . The similarity plots can thu s provide three things : a ready indication of the magnitude of the Bowen ratio ; an indicatio n of the direction of the H and E fluxes ; and an identification of levels suited for the Bowe n ratio analysis . 247
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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
Page 25 and 26:
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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Page 55 and 56:
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
Page 69 and 70:
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
Page 91 and 92:
Table 3.-Predicted plant response i
Page 93 and 94:
Walker, Reed, Scott, and Webb are c
Page 95 and 96:
Water and Nutrien t Movement Throug
Page 97 and 98:
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
Page 107 and 108:
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
Page 187 and 188: Table 2 .-Annual litter fall in Col
Page 189 and 190: Table 4. Biomass and growth increme
Page 191 and 192: Table 6.-Annual turnover from certa
Page 193 and 194: Kiil, A. D. 1968. Weight of the fue
Page 195 and 196: condition differ) ; the turnover ra
Page 197 and 198: proportionally about the same for e
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: (3 = H/AE=yo$/De (3 ) where y is th
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 and 246: 1970. Evapotranspiration an d meteo
Page 247 and 248: may bias the results . Meteorologic
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
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Table 1.-Suggested criteria for jud
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Table 4.-Average C, N, and P conten
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during 1963 to 1967 and from Lake S
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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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