IBUSDA FOREST SERVICEGENERAL TECHNICAL REPORT NC-58

EN_RGY&WOOD

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_1 _RGY&WOOD.NorthCentral Forest ExperimentStationForest Service, U.S. Department of Agriculture

North Central Forest Experiment StationForest Service - U.S. Department of Agriculture

1992 Folwell AvenueSt. Paul, Minnesota 55108

1980

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

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" fromintensivelycultured plantations:.research anddevelopmentprogram

" . TABLEOF CONTENTS. Page

Background ........................................................................................................2Selection of promising species .................................................................5

, Stand establishment methods ..................................................................6. Fiber and energy yields in response to spacing

and harvest cycles ...................................................................................8Yield response to nutrient and moisture regimes ............................10Effect of crown architecture and canopy density on yield ....... 11Physiological factors influencing yield ..................................................13

Raw material quality of intensive culture trees ................................14Diseases of intensive culture species .....................................................17Insect problems in intensive culture ......................................................18Design of mechanized equipment for intensive

culture systems ...........................................................................................19Cost of producing wood for fuel and fiber ........................................20Industrial cooperators ....................................................................................21

. Publications ........................................................................................................24

The first small plot experiments were established in 1970to test the growth of various Populus clones and the

BACKGROUND effect of spacing on yield.

eration with industries, and the collaboration of:The Maximum Yield Work Unit was established in scientists from different disciplines in a systems ap-

1971, by the North Central Forest Experiment Sta- proach. The research team now includes silvicultur-tion in response to concerns expressed by both indus- ists, physiologists, an ecologist, geneticists, a soiltrial foresters and researchers. Industrial foresters scientist, hydrologist, a wood technologist, a patholo-realized that new systems for growing more fiber on gist, an entomologist, an engineer, and an economist.less land must be explored because of escalating fiber Supplemental funding from the Department of En-

• _ demand, increasing demand for recreation and non- ergy since 1977 has enabled researchers to accelerateforest uses of forest land, rising land prices and tax progress in several problem areas, with emphasisrates, and increasing harvest and transportation placed on the development of methods to plant treescosts, and ensure their early survival. Establishment is the

. Forestry researchers realized that much basic ge- most critical problem in the short-rotation-intensive-netic, physiological, and cultural knowledge could be culture (SRIC) system because larger research stud-applied if environmental conditions forgrowingtrees ies or large-scale industrial plantations cannot becould be more closely controlled as in agriculture, established until the technology to successfully plant

•Research was begun to select promising species, es- hardwood stands has been developed. Although prac-tablish intensively cultured plots, explore new har- tices for planting softwoods were developed long ago,vesting methods, evaluate pulping qualities of the no system for consistently establishing plantations offiber, and assess the economic viability of this sys- hardwood forest trees in the upper Midwest has beentem. This program used a systems approach, with developed (except for the shelterbelt plantings of theresearchers from many different disciplines working northern Plains). The problems in large-scale plant-together, ing operations are often different from those nor-

In 1976, the program was expanded to incorporate mally encountered in small plot experiments, and theboth developmental and basic research, active coop- additional funds have enabled researchers to provide

information to help industry establish larger pilot- The USDA Forest Service's Maximum Yield ofsized plantations. Wood and Energy from Intensively Cultured Planta-

tions Research and Development Program includestwo Research Work Units as well as scientists from

More than 10 acres a year of intensively cultured other Research Work Units within the North Central

plantations are being established at the Harshaw Forest Experiment Station. Research problems, ob-Experimental Farm near Rhinelander, Wisconsin. Era- jectives, and results will be presented separately inphasis is on developing cultural practices and mechan-ized equipment suitable for operational plantation this report for each problem area, although this doesmanagement, not accurately represent the overlap and interaction

between problem areas due to the complex set offactors that determine biomass yield.

Briefly, the SRIC concept is that plantation bio-mass yields can be greatly increased by using geneti-cally superior planting material and optimizing fieldenvironmental conditions. Generally, hardwoodshave been tested more thoroughly for intensive cul-ture systems because of their rapid juvenile growthand their ability to sprout from the stump after theyare harvested, thus eliminating the need to replantthe trees.

The establishment of intensive culture plantationswith most species in any region of the United Stateswill likely include essentially the same kinds of oper-ations, although the precise nature of these opera-tions will vary greatly by species and site. Many ofthese concepts are more typically termed _agricul-tural" rather than _silvicultural" in nature.

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One of the most critical problems in establishing theshort-rotation-intensive-culture system is weed control.Weeds are a serious competitor during the first 2 years,and research in weed control methods has recently beenexpanded.

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First, the land must be cleared and plowed to elimi- fertilizing and irrigating. Diseases and insect pestsnate other plants and to make the site suitable for are also controlled.planting and cultural equipment (i.e., abandoned After 6 to 10 years, at a time when the trees reach

farm land is well suited). Seedlings or cuttings are near-optimal biological growth, the trees could beplanted with mechanical planting equipment at var- harvested using specially-designed harvesters. Theied distances from a few centimeters to several me- wood will likely be chipped and used for energy, pulp,ters within the rows that are from 1 to several meters reconstituted wood products, feed, chemicals, or anyaPart.The first growing season is critical to the sur- combination of these products. In the spring follow-vival of the small trees, and plantations must be kept ing harvest, several new stems will sprout from eachfree of weeds either by cultivating, planting a cover cut stump (coppice), and these will become the nextcrop between the rows, applying an herbicide, or crop of trees.other means. Each growing season the trees are pro-vided optimal amounts of nutrients and water by

" Irrigation is one of the culturalpractices being studied inthis research program. More precise information about

. the quantity and timing of irrigation is still needed.;.

SELECTIONOF PROMISING SPECIES

These plots were established in 1974 to test the perform-ance of different Populus clones. Note the differences ingrowth rate of these clones after 3 years under similarintensive culture conditions. Research Results

The genus Populus (poplars and cottonwoods) wasselected for the early experiments because of its rapidjuvenile growth, ease of hybridization, vegetative

Research Problem propagation,and the vast amount of information al-• ready known about its growing requirements. In

The characteristics ofhigh-yielding trees for inten- 1971, 30 Populus hybrid clones were tested in field

sive culture are significantly different than those for plots at Rhinelander, Wisconsin, and Ames, Iowa.conventional forestry. Selected species must be bio- Fourteen of these have been selected for further test-

logically efficient to take full advantage of the optim- ing under various intensive culture techniques.ized conditions of intensive culture. Other species tested included jack pine, (Pinus bank-

siana), larch (Larix laricina), alder (Alnus), and

Research Objectives green ash (Fraxinus pennsylvanica).Rapid laboratory screening tests have beenPromising species and clones must be screened for conducted using physiological and morphological

a wide range of biological and physical properties, characteristics, such as net photosynthesis rate, pro-Initial tests include growth rate, response to different duction of enzymes controlling nitrogen uptake andspacings, response to water and nutrient man- metabolism, branch angle, and leaf orientation onagement, sprouting ability, insect and disease re- branches.sistance, wood quality, and adaptation to regional Controlled-environment chamber experimentsclimatic conditions. As results from physiological were also completed for 25 Populus clones using 3studies of crown architecture, photosynthesis, and different combinations of growth period and temper-transl0cation of photosynthetic products are ob- ature. After comparing total biomass, leaf weight,tained, they will be included in genetic selection and stem weight, height, and leaf number at 8 weeks, 14breeding programs, clones were recommended for field testing.

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STAND-ESTABLISHMENTMETHODS

Weed competition is one of the most serious problems in Planting low lying leguminous cover crops may be anestablishing hardwoods for intensive culture. In field effective way of simultaneously providing soil nitrogenexperiments, the herbicide "'Roundup'" was found to keep and controlling weeds. White Dutch clover shown herestands almost free of weeds, prevents the growth of taller weeds that might otherwise

shade and compete with the hybrid poplar cuttings, butis also competitive with the trees.

Research Problem and chemical weed control; and mechanization of• cultural operations will be studied. In particular,

The survival of trees during the critical first 2 conventional farming techniques will be tested. A1- 'years is primarily determined by vigor of the plant- ternative vegetative propagation systems will being stock; adequacy of site preparation, fertilization, studied, including methods for collecting and storingand irrigation; and control of competing weeds. Be- cuttings, methods for obtaining plants from green-cause early site occupation is desired for intensive house stock plants, methods for stimulating the root-silviculture systems, high survival of planted trees is ing of clones that are difficult to root, and possiblyimportant. Stand establishment techniques have not systems for establishing cuttings in containers.been Well developed for hardwood plantations, al-

though application of agronomic and horticultural Research Resultsmethods offer promise. Studies began in 1978 to test the effectiveness of

Research Objectives 245 combinations of methods of weed control in both• spring and summer plantings were evaluated afterIt is expected that plantation establishment meth- the first year. The best site preparation methods were

ods for Populus clones will be developed during the chisel plowing or a combination of moldboard plow-next 5 years to attain a survival rate of 90 percent, ing to 9- to 10-inch depths followed by disking andMethods for site preparation; mechanical, biological, spike-tooth harrowing. Crownvetch and birdsfoot

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. Weeds may be controlled by mowing, a method that is° widely used in orchards.

trefoill both leguminous nitrogen-fixing plants, werethe most. effective cover crops for stimulating t_eegrowth during the first year, but were not effectivewhen evaluatedthe second year. "Linuron" and and survival for all planting dates. Rooted hardwood'_Roundup" herbicides were the most effective herbi- cuttings in _Tubepak" containers provided no advan-cides when no other weed control method was used. A tage in either survival or height growth. Bare rootedcombination of a crownvetch cover crop together with tip cuttings performed poorly for all planting dates.herbicide _Treflan" was slightly better than any Some of the fastest-growingPopulus clones, in par-other weed control treatment, ticular, P. alba L. x P. grandidentata Michx. hybrid

'One year of data is by no means conclusive, and the (Crandon), are difficult to establish vegetativelymabove-average rainfall during the growing season less than 50 percent of the cuttings rooted usingmay have produced different results than a similar normal greenhouse practices. However, rooting

experiment in a drier year. However, this study pro- greenwood tip cuttings in greenhouse fiats at tem-Vides preliminary information regarding promising peratures of 76 ° to 85°F provided 70 to 100 percentsite preparation and weed control methods that rooting success, faster rates of root elongation, andshould be tested in larger plantings, less mortality from fungal and bacterial infections.

The optimal propagation method may vary with Hormone treatments increased rooting success andthe time of planting. In this study, soaked and un- number of roots per cutting, but hormone concentra-soaked hardwood cuttings had the best height growth tion was less important than temperature.

Containerized Populus cuttings are grown in the green- New greenhouse methods such as hydroponics are beinghouse in preparation for planting. The survival rate of tested for mass production of rooted greenwood cuttings.these rooted cuttings will be compared to that of This method may be more economical for establishingunrooted cuttings to determine the most effective meth- cutting orchards because it uses less greenhouse spaceods of Stand establishment, than containerized stock.

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FIBERAND ENERGYYIELDSIN' RESPONSETO SPACINGAND HARVESTCYCLES

fore, essentially all the sunlight is intercepted by theleaves before it reached the ground. Closely spacedstands also attain maximum mean annual produc-tion early in the rotation, but the competition be-tween trees begins to reduce the annual biomassproduction per tree. In addition, closely spaced standsare more expensive to establish and it is doubtful that

, these additional costs can be recouped through, higher yields. Because the mean annual production, is closely related to the stand's leaf area index (leaf

surface area per unit land area), it appears that earlyoptimization of leaf area may increase yields, much

" as cultural systems to optimize leaf area index inagriculture have been successful.

Research Objectives. Preliminary research on small plots to determine

the effect of spacing and rotation age on yields hasalmost been completed, and researchers are cur-rently evaluating the most promising spacings androtation ages on yields of larger field plots. From theresults of specific studies they will establish mathe-matical relations between total tree dry weight andeasily measured variables such as diameter andheight, determine effects of spacing on dry weightdistribution among tree components, and determineleafbiomass and leaf area index with respect to vari-ous yields. The optimal combinations of spacing and

• rotation will be studied for the maximization of fiber

and energy production in stands of Populus, alder(Alnus glutinosa), jack pine, and larch. The distribu-tion of major nutrients within the stands will be

Trees planted at close spacings will quickly occupy the studied and effects of frequent harvesting on nutriententire site. After 6 years, essentially no sunlight will

. reach the ground in this stand, which was planted at 0.6 budgets will be determined.rn x 0.6 m spacing. An integral part of biomass production studies is

determining the efficiency of solar energy utilizationby plants. This energy data is particularly needed for

Research Problem evaluating systems in which tree plantations wouldbe utilized as an energy source. By comparing the

One Of the keys' to maximizing fiber and energy heat of combustion of harvested biomass to the en-production in forest stands is to optimize cultural ergy requirements for intensive culture, the netpractices-- the spacing and rotation age for the se- energy gains will be assessed.lected species and clones. In particular, information

is needed on the efficiency of capturing solar energy Research Resultsby plants and the energy relations in intensivelycultured plantations. Early field tests of closely-spaced Populus 'Tristis'

• It is known that closely spaced stands (1 × 1 m or hybrids showed that total aboveground biomassless) fully occupy the site within a few years; _here- yields could exceed 20 dry tons/ha/year for 4-year-old

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trees grown under intensive culture. Tree growth ulus and 4.7 forjack pine, with a net energy content ofand competition information from these plots was 306 MBtu/ha for Populus and 236 MBtu/ha for jackthen used to model stand growth and project yields pine. When comparing the net energy ratios for in-for 10-to 25-year rotations. The table below summa- tensive culture systems and naturally regeneratedrizes both the observed yields on small plots, and the forests, it appears that net energy returns areprojected yields of stems and branches (Ek and linearly and positively related with the energy in-Dawson 1976): vested in the system. Although net energy ratios of

up to 157:1 have been reported for natural forests, theStem-Branch Biomass Yield energy produced annually per acre by these stands is

very low. To meet future fiber and energy demandsItem _ Spacing from forests, more intensive systems will have to be

0.23 m 0.30 m 0.61 m 1.22 m used, and it appears that these systems will be effi-

t/ha/yr-, cient producers of energy./

Actual yields:4 years 11.3, 13.0 7.5 _ ' Many hardwoods will coppice or sprout from the stump

after cutting thus eliminating establishment costs forProjected yields: the next rotation. The vigor of coppice growth will differ

10 years 17.0 16.5 16.0 15.5' greatly by species and clone and must be determined in15 years m __ -- 29.0 field tests.20 years " _ _ _ 36.0

Field Studies have shown that 1.0 m spacings willhave the same annual yields as 0-.23m spacings after4'to 6 years. Therefore, field tests of selected clones

haven0w been established to test spacings up to 2.0m and the effects of various cultural practices onthose spacings.

Although hardwoods have been used most com-monly in intensive culture studies, yields ofsoftwoods may exceed those of hardwoods on certainsites. Hardwoods are site-demanding, and the estab-lishment of hardwoods on poor sites may be uneco-nomical because of heavy fertilizer and weed controlrequirements. Intensively cultured plantations of 7-year-old tamarack (Larix laricina) were found to pro-duce 4.3to 5.2 tons/ha annually, when planted at

• cIose spacings, fertilized, and irrigated. Under simi-• ,lar conditions, 7-year-01d jack pine produced higher

yields, ranging from 6.8 to 8.1 tons/ha annually. Op-tional spacings will be determined by the expectedrotation age; for example, the maximum mean an-nual increment for the 0.23 m x 0.23 m spacingsoccurred at age 6 for tamarack and age 5 for jack pine.As spacing.increases, the corresponding rotation ageincreases also.

The use of such intensive culture methods as fertil-

ization, irrigation, and cultivation appears to be anefficient use of energy. The ratio of net energy gain tototal energy utilized was calculated to be 4.3 for Pop-

YIELDRESPONSETO NUTRIENTAND MOISTUREREGIMES

A traveling irrigation system is used toprovide water forthe large field experiments. During operation, a water

Research Problem turbine powered winch advances the unit along a cableanchored at one end of the irrigation lane. The unit is

Conventional silvicultural practices have histori- drawn by tractor back to the starting point at thecally provided less than optimum nutrient and water beginning of each day that irrigation is required.

supplies to trees, and therefore tree growth has notapproachedthe biological potential of the species.Traditional practices reduce the number of trees on a promising species and/or clones are not known. Thesite to allocate the fixed supply of water and nutri- growth responses with regard to fertilizer applicationents to fewer trees. With SRIC systems the number of rate, formulation, placement, and time all must be

trees (spacing) is fixed at the time of planting and the determined experimentally. Furthermore, the inter-problem is to determine the quantity of water and action of irrigation and fertilization in affecting plantfertilizer necessary for maximum yield. Related growth will be studied. Research in growth-room,problems are to determine the timing of fertilizer and greenhouse, and field studies will be conducted towater application and the extent to which nitrogen- identify the soil-water potential and nutrient levels

fixing plants may be introduced into intensive of the plant and soil for maximum plant growth forselected clones. Also, changes in physical and chemi-Culture plantations to reduce costly nitrogen

fertilization, cal soft properties and ground water quality will beidentified.

Research ObjectivesResearch Results

Gross plant nutrient and moisture requirementsare known for the genera under consideration for A Continuous Function Design was used in field

• intensive culture, but the specific requirements for experiments, with a moisture gradient superimposed

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at right /ingles upon a fertilization gradient. Theeffects of the independent variables (water and nitro-gen level)and all the combinations of these two vari- [_FFFCT OF CROWN

ables on the groWth of hybrid poplar were thus tested ARCHITECTUREANDon V4-acre plot. The water was provided by a trickleirrigation system and the fertilizer, ammonium ni- CANOPY ON YIELDtrate, was applied by hand. Measurements after thesecond year show that up to 2 inches of irrigation perweek considerably increased height growth, whereasadditional amounts of irrigation (more than 3 inchesper week)inhibitedheight growth. Fertilization with!00 lbs/acre/year nitrogen as ammonium nitrate in- _creased height growth as much as 30 percent. Addi-tional amounts of nitrogen decreased height growth.A smaller plot with an irrigation gradient andincreasing percentages of nitrogen-fixing Alnus glu-tinosa planted among the Populus showed that Pol?u-lus height growth increased about the same whenmixed with a large proportion of Alnus as when fer-tilizer weis applied. _This has significant implications _for reducing fertilization costs in intensive culture

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Light interception is related to both the number of leavesper tree and the leaf area per tree. Leaves of selectedPopulus clones grown under SRIC may exceed 30 cm inlength, and provide a large surface area for lightinterception.

ProblemThe amount of sunlight that leaves intercept is

greatly dependent on the arrangement of leaves onthe branches (crown architecture) and the density of• ,

leaves within the stand canopy. This captured light,in turn, directly affects the amount of photosynthetic

, activity and total biomass production. When the mostadvantageous leaf arrangement on branches isknown, trees with these characteristics can be se-

• lected for clonal testing under SRIC.A trickle irrigation system is used forprecise application Total biomass production in both agricultural andof water in irrigation studies. Microtubes dischargewater at 4-foot intervals along the ½-inch plastic pipe. silvicultural systems is closely related to total leafThe nutrient gradient was established by hand applica- area of the stand. Two of the major limitations totion of fertilizer, productivity of plants are the length of time required

to obtain the optimum leaf area index and the abilityto maintain that optimum leaf area. The low produc-tivity of many forest stands is partly due to thelengthy period of time required to achieve optimumleaf area. A goal of SRIC forestry is to increase the

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effective leaf area earlier in the rotation and main- and concomitant rapid growth depends greatly on thetain it longer than more conventional forest systems, high density of trees in the early years of establish-

The suitability of trees grown under SRIC for pulp ment. In SRIC forestry leaves are concentrated on aproduction also depends partly on the distibution of large number of individuals rather than a few as inbiomass among tree components. Crown architecture more conventional forests.will influence the percentage of biomass in branchand stem wood, and thus affect quality of yield forpulp and other wood products.

Research ObjectivesThe '_ideal" tree for intensive culture will be fur-

ther defined through studies that evaluate the effectof crown architecture and canopy density on yield. Toidentify these attributes, scientists will de_ermineleaf development throughout the growing season,light interception by leaves within the stand, andaffect_of crown architecture on distribution of photo-synthetic products within the tree. Studies will alsoaddress the affects of growth regulators on leaf pro-duction and the affect of spacing, cultural practices,and age on canopy characteristics, t _ '__

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• Research Results Leaf area index describes the surface area available for

Distribution of the number of leaves per tree and photosynthesis in forest stands and is one of the bestindicators of photosynthetic capacity. Automatic mea-the leaf area index was studied in a 5-year-old stand surement of the surface area of each leaf using thisofPopulus _Tristis' grown under SRIC at 1.2 m spac- instrument has greatly accelerated research in this area.ing. Average leaf area index was 7.6, which is 1 to 5times higher than reported natural stands of Populusin the same area. Trees contained an average of more Observation of the vertical distribution of leavesthan 6,600 leaves or 4,800 leaves per square meter, within the canopy showed that about 25 percent ofThe percentage of leaf area on long shoots was 53 the leaf area produced on 3-year-old Populus _Tristis'percent, compared to 10 to 20 percent on trees grown was on the terminal shoot. Because photosynthatesin native stands. Leaves on short shoots are produced produced by the terminal shoot leaves are directlyearly in the growing season and mature early. Long translocated to the stem, greater proportions ofshoots produce leaves continually during the grow- leaves on the terminal shoot will no doubt increaseing season, thus providing an advantage of con- stem biomass production. The lower branches of in-tinuous production of photosynthate throughout the tensively cultured trees retain their leaves longersummer, than those of conventionally cultured trees, which

During the first 3 years, leaf area per tree and results in an even greater leaf surface area for lightnumber of leaves per tree for several Populus clones interception. This retention can most likely be attrib-were not affected by planting densities from 0.2 to 1.4 uted to the optimum growing conditions of inten-meters. Thus, attainment of high leaf area indices sively cultured trees.

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PHYSIOLOGICALFACTORSINFLUENCINGYIELD

Gross photosynthetic rates of Populus are measured inthe field using a 14C0 2 technique. Measurements of leafc'onductance, leaf and air temperature, relative humid-ity, and photon flux density are made concomitantly toprovide for the proper interpretation of photosyntheticrates.

The C02 compensation point of excisedPopulus leaves isProblem measured in the laboratory. Such information about

physiological responses may be used to preselect clonesPh0tosynthates (mostly sugars) are produced in before expensive field screening is conducted.

the leavesduring photosynthesis and are then trans-located to all other parts of the tree. These photosyn-

thetic products may be used for maintaining plantprocesses (respiration) or for producing biomass.Therefore, the net biomass production is dependent

on the rates of photosynthesis and respiration, aswell as on the distribution of photosynthates among

plant parts.Numerous physiological variables have been iden-

tiffed through extensive agronomic research as im-

portant determinants of biomass production in cropplants, but the importance of most of these variableshas not been determined for woody plants. Whenmore information about the desirable characteristics

of trees for SRIC systems is'available, genetic tree

improvement programs can incorporate these traitsinto selections.

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Research Objectives leaves are exposed to 14C02 in the field. Three

days later, the whole tree will be harvested and the _4C02The relation between physiological variables and activity will be measured in the leaves, branches, stem,

the quantity and quality of yield for selected trees and roots.°

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grown under intensive culture will be studied. Thesevariables will include rates of photosynthesis andrespiration, photosynthetic efficiency, patterns of RAW MA__AL

photosynthetic activity during the growing season, _J_L_W O_ ___$__L_patterns ofphotosynthesis within the tree crown, andpatterns of photosynthate distribution within the C_LI__D l__tree. Recommendations for selecting trees can thenbe based on the complex system of physiological vari-ables know to affect yield.

The methodology for conducting physiologicalstudies on trees in the field is not available, partlybecause of the size and complexity oftrees. Therefore,considerable effort will be needed to develop fieldphysiological research techniques for young inten-sively cultured trees.

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Research ResultsField, greenhouse, growth chamber, and labora-

tory studies have been initiated to measure the rateof net photosynthesis, leaf conductance, and CO2compensation points of individual leaves at variouspositions within the canopy throughout the growing

' season. Concurrently, the translocation of photosyn-thates is measured by exposing groups of three fully-expanded contiguous leaves to _4CO2. Trees areharvested after 72 hours and sampled for percentage0f _4C-activity in various tree components to Scanning electron micrograph of a tension wood fiber

from short rotation intensively cultured Populus tree.determine the translocation of photosynthates pro- Surface dislocations (wrinkles) on the fiber affectduced during the exposure to 14CO2. Laboratory subsequent paper strength properties (2000X).experiments to confirm exposure and samplingmethods have been completed, and as trees growolder and more complex it is expected that more so- Problemphisticated field sampling methods will be developed.

The value of biomass produced under SRIC sys-Field experiments with young Populus trees grownunder SRIC have provided some preliminary results, tems depends primarily on the type of specific prod-The upper leaves translocate photosynthates upward ucts for which it can be used. Because wood is such afor use. in shoot development, the middle leaves tran- versatile raw material, an integrated research pro-slocate photosynthates both upward to the shoot and gram must consider the value of wood produced un-downward to the lower stem and roots, and the lower der intensive culture for a wide range of current

' nonexpanding mature leaves translocate primarily products as well as those that may be demanded indownward to the lower stem and roots, where they the future.are utilized for vascular and structural tissues. These Intensive culture practices influence physiological

results suggest that because mature leaves contrib- processes which in turn affect the anatomy, chemicalute mainly to stem wood production, it may be desir- composition, and physical properties of the raw mate-able to select for trees that retain mature leaves, rial and therefore the usefulness of the material.

Research Objectives•- The effect of such variables as plant material, spac-

ing, fertilization, moisture regimes, and age on thequality of raw material will be determined. Tests willbe made to measure the suitability of raw material

• produced by SRIC (including bark) for pulp and pa-per, particleboard, fiberboard, chemical feedstocks,

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energy, _ind animal feed. For the purposes of genetic types with low lignin contents. When conversionselection and breeding programs, the most desirable processes and wood quality needs for these processesraw material attributes for trees grown under inten- are better defined, research in this area will be moresive culture will be identified, appropriate.

The primary concerns associated with the use ofResearch Results rapidly grown juvenile wood for pulp and paper are

that high percentges ofbark may be present in whole-The energy content of most woods is similar-- tree chips and that juvenile wood has shorter fibers.

hardwoods average 4,400 and softwoods average than mature wood, which can adversely affect pulp5,000 kcal perkg of ovendry wood. The factors that yields and paper strength.contribute to differences in energy value of wood are Most anatomical characteristics vary greatly bythe moisture content, density, and the ease of drying species and clone and thus are important selectionbefore conversion. Density will also affect transpor- factors that affect utilization. Anatomical studiestation costs and may affect rates of conversion. Tests have generally shown higher percentages of springof juvenile _Populus wood grown under SRIC have wood and transition fibers in wood grown undershown that moisture content and density are not SRIC; this fact is probably the reason for lower spe-significantly different from wood grown under con- cific gravities for conifer wood grown under intensiveventional systems, culture. Intensive culture jack pine and larch fibers

Wood quality may be important in indirect energy were only one-third as long as fibers from older ma-conversion processes and for the utilization of wood ture wood, but improved pulping processes haveas liqtiid fuel and chemical feedstock. For example, made fiber length less important. However, morelignin may.hinder the conversion proces s, and ap- reaction wood is produced under intensive culturepropriate plant selections could be made for geno- than under conventional silvicultural practices prob-

ably due to the accelerated growth rates.• In one study pulp yields of tension wood and nor-

Trees from the.first SRIC plots are used for a multiple of mal wood were 60 and 53 percent, respectively. A1-research purposes. After they are weighed to determinetotal above-ground biomass yield, the wood is used inutilization tests.

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though paper from tension wood had inferior performance of SRIC produced wood, which could beStrength properties to that from normal wood, the decreased by longer rotations and improved methodsproperties of kraft paper produced from SRIC Popu-. of whole tree chip segregation.lus are still within acceptable ranges. Tension woodfibers resisted collapse during beating and produceda thicker, more porous sheet, but the pulp was stillclearly acceptable after refining.

Wood produced from 8-year-old jack pine and larchgrown under SRIC was also found to be acceptable forkraft pulping, with 41 percent pulp yield for jack pineand 39 percent for larch. On the basis of handsheetstrength tests including burst, tear, and tensile,larch was slightly superior to jack pine. The accepta-

biliW of Populus and the conifer raw material pro-'duced under a SRIC system differed little. Thus, itwas concluded that biomass yield and clonal differ-ences are the major factors for determinin_ the mostpromising.species and clones for SRIC.

" This whole-tree chipper automatically separates some ofthe foliage from the chips. The chips may be further

I separated by the Vacuum Airlift Segregation process.

Intensive cultured Populus may also be suitable asa raw material for producing flakeboard, a structuralparticleboard. Tests on five Populus clones showedclonal variation in board strength properties, withthe better clones producing boards exceeding indus-trial guidelines for strength properties. Bark reducedboard strengths much less than was expected.

• Another alternative use for Populus foliage is ani-mal feed supplement. Recently matured Populusleaves have been found to contain levels of nitrogen,

WOodproduced under intensive culture has been found carbohydrates, and pigments comparable to forageto be acceptable for kraft pulping. The wood may also be

' suitable for thermornechanical pulping, crops. Feeding tests with ruminants showed the foli-. age to be acceptable, although the palatability of

clones differ.

Wood grown under SRIC was also tested in thermo- To alleviate the problems resulting from high barkmechanical pulping processes, which offers the content in the manufacture of both reconstitutedadvantages of higher, yields and lower capital invest- wood products and pulp and paper, a vacuum airliftments than kraft pulping. Tests showed this wood to segregation (VAS) process was developed to separatebe inferior to pulps obtained from mature wood be- whole tree chips into components-- wood chips, bark,cause fiber lengths were shorter; fiber length is more foliage., and fines. In the VAS process, chips arecritical for obtaining paper strength for thermome- spread over a continuously moving wire mesh con-chanical pulps than for kraft pulps. However, optical veyor belt that passes under a series of vacuumproperties were generally good, which suggests that hoods, which separates the components on the basisblending of mechanical and kraft pulp may be possi- of differences in terminal settling velocities of the

' ble. Bark content was a major factor in the lower particles.

16

DISEASESOF INTENSIVELYCULTUREDSPECIES

Popu!us foliage has been found to be acceptable rumin-ant feed, although the palatability appears to vary byclone.

Processing systems such as the VAS offer numer-.ous alternatives for the utilization of the biomass,depending on the market demands ana industry ob-jectives. Four single- and multiple-use alternativesystems are summarized below for 5-year-old Popu-lus grown under SRIC at 1.2 m spacing.

•System Pulp yield Energy FeedMetric ton/ M kcal/ Metric ton/

hectare hectare hectare Leaf rust causes defoliation of Populus before the end of• . the growing season. As shown, severity of damagePulp only 42 _ _ varies between clones so selection will be made for thoseEnergy only _ 200 _ clones that are least susceptible to leaf rust.Pulp and

energy 27 68 -- Research ProblemPulp, energy,

. and animal Intensive culture systems may be more vulnerablefeed. 27 48 5 to disease than conventional mixed species stands

because they contain only a few species or hybridsand they may facilitate transmittal of pests becausethey are closely spaced. At any rate, the susceptibil-ity of a species to pests and the possible control meth-ods must be determined before any species or clone iswidely planted.

Research ObjectivesIt is well known that Melampsora medusae leaf

rust, Marssonina brunnea leaf blight, and Septoria

17

"musiva Peck leaf spot and canker are the most preva- be greater than in forests with a wide range of specieslent poplar diseases in the United States. The suscep- and ages. However, the SRIC system affords the op-tibility of various Populus clones to these and other portunity of using cultural tools to control insectsdiseases will be determined through this research, before they become destructive.Additionally, the incidence and severity of these dis- Natural enemies of Populus include more than 150eases within the north-central region of the United insects. The most destructive of these are leaf aphids,States will be examined. Integrated control methods which feed on leaves and ultimately defoliate thetoreduce damage from these diseases will be recom- trees. Jack pine and larch also have numerous defoli-mended, ating, sapsucking, and shoot-stem boring insect

pests.Research Results

Research ObjectivesThe screening of clones .for disease susceptibility

throughout the intended establishment range is ex- Insect damage depends on the number of insectstremely important. Populus clones were planted at attacking the tree or stand, the part of the tree in-each of 13 sites throughout the Midwest in 1976 and fested, the season of attack, and the age of the tree.1977, withan intent to monitor the plots for 10 years. _ After the potential insect pests are identified, clones

:After one growing season, it was found t_at the most resistant to these pests may be selected, althoughserious diseases were Marssonina leaf spot, Melamp- resistance includes extremely complex factors such

"sora leaf rust, Septoria leaf spot, Cytospora canker, as nutritional status and vigor of the tree.and Septoria canker. The severity of each of the dis- Control methods for insects in intensive cultureeases varied widely in the region, systems will be identified. These may include site

Leaf rust injures trees by causing leaf damage and preparation to eliminate insect habitats occupied indefoliation, and when severe, increases susceptibility other stages of the life cycle, fertilization to improveto other diseases. Incidence was found to vary greatly nutritional status of the tree or alter tissue compo-

' between clones, and fungicide treatment delayed de- nents essential for specific insect pests, irrigation tofoliation but did not prevent severe rust damage for eliminate the water stress conditions that are oftenone hybrid, P. deltoides x P. balsamifera 'Northwest'. causes of insect outbreaks, and hybridization to alterInfection is usually most severe on lower leaves, thus plant density. Close planting may provide stress fromit generally affects basal diameter growth but not competition or modify environmental conditions toheight growth, limit some insects and favor others.

Research Results

Insect damage has been surveyed on establishedintensive culture plots of Populus throughout theNorth Central States. Aphids, Chaitophorus populi-

• toliae (Oest.), were found to cause the greatest defoli-ation damage, although considerable differences in

: severity of attack were observed among clones.Further tests on the impact of defoliation in rela-

tion to clone and spacing have begun. An experimentto test the effects of various degrees and timing of

II_OEI_,,|IkI__TP_O_L___ [_ defoliation on yield is in progress--certain percent-d

[_T_$[V_ CULTV_ ages ofleaves are manually removed at various timesduring the growing season. The effects of girdlingand boring damage will be determined in similarexperiments by physically damaging the trees. Whenthe season and severity of impact can be relatedto actual yields, cultural control methods will be

Research Problem prescribed.

Because intensive culture crops are expected to befairly uniform in species, age, spacing, and geneticcomposition, the potential for insect outbreaks may

DESIGNOF MECHANIZEDEQUIPMENTFORINTENSIVECULTURESYSTEMS

tensive culture systems may eventually be developedif these modifications do not perform satisfactorily.In particular, equipment needs for planting, cultiva-tion, fertilization, and irrigation will be assessed.

Probably the most critical need is for appropriateharvest equipment. Design criteria for a small-diam-eter short-rotation harvester are currently being de-veloped, and preliminary designs for the cutting headare already underway.

Research Results

Engineers working with this program have modi-fied existing tree planting equipment to accommo-date the large unrooted and rooted cuttings used inthe large-scale field plantings. These modificationsThis tree planter was modified for planting unrooted

cuttings. The operators place the 8-inch cuttings ver- are currently being tested in th e field and will betically in a trench and the planter wheels pack the soil further improved as operational data are obtained.around them. Similarly, a traveling irrigation system to deliver..

water over 3 to 9 m-high trees has been installed forthe large field plantings. The irrigation system per-

Research Problem formance will be critical as the trees increase in

Labor costs are rising in all sectors of the economy, height toward 9 m or taller, because the system mustand forest and agricultural operations have become be able to deliver water uniformly over the land area.increasingly mechanized in order to lower production preliminary design criteria have been developedcosts. Intensive culture systems must also be mecha- for the mechanized harvest equipment. In general, itnized. Although they require many cultural op- must be capable of harvesting one or more rows of theerations widely practiced in agriculture, commercial plantation at one time, severing each tree sequen-agricUltUral equipment is generally not suitable for ....t_ially in the row, and forwarding the material to thetree crops, landing site. The lack of information about optimal

Researchers have improvised equipment for plant- spacings and rotation age (and thus stem diametering cuttings, cultivating, and irrigating. Small re- and height) make the design efforts and equipmentsearch plots have been harvested with chain saws. development a continuous process. Consequently, it•Yet these methods will be impractical for even the is highly unlikely that the first generation of small-,large-scale pilot plantings already established. Har- diameter harvesters developed will be those which

are ultimately commercially produced.vesters used for current silvicultural operations arenot suitable for closely-spaced stands, which have To ensure an acceptable level of regeneration bysmall stems, and multiple stems on each stump after coppicing, the harvester must make a clean cut sur-the first rotation. An entire systems approach must face and provide minimal pressure against thebe developed for harvest, collection, and delivery of stumps and root systems. It must be able to cut at low .wood to the pulp mill or energy conversion facility, stump heights and handle the multi-stem tree that

will develop in coppice rotations of hardwoods. The

Research Objectives wood will probably be used as chips, so the harvestermust simultaneously chip the wood or a whole-tree

Modifications of commercial agricultural and chipper must be present at the landsite. Existing chiphorticultural equipment will be investigated first, trucks will be suitable for final transport of chips toalthough substantially different equipment for in- the mill or conversion site.

.

19

Before intensive culture management will bewidely accepted by land managers, however, detailed

CO_ _O_ _O__C_ __ WOO_ information on the production costs and anticipated

_O_ __ __D ___ revenues must be obtained. Estimates of the eco-nomic feasibility of intensive culture systems forfiber and fuel are needed to compare with conven-tional silvicultural systems for fiber and alternative..

energy supplies, such as coal. Although only prelimi-nary econSmic analyses can be made with the infor-mation'now available about yields under specifictreatments, the sensitivities of the final productioncosts to various cultural treatments are needed byresearch scientists.

Until basic SRIC growth information under spe-cific treatment regimes is readily available, eco-nomic evaluations will be partially made by using abreak-even analysis technique. Break even analysis

• permits the physical yields (e.g., dry tons per acre) orfinancial yields required to cover all costs included ina specific production schedule to be estimated. Inaddition, the sensitivity of total production costs toindividual costs such as land rent, stand establish-ment, fertilization, irrigation, and harvesting will bedetermined.

• As better biological growth information and pro-duction management inputs are obtained fromlarger-scale plantings, more sophisticated economicanalyses for calculating present net worth and inter-nal rates of return will be incorporated into the eval-uations. For example, cashflow analyses will be usedto calculate costs and benefits of growing Populus_Tristis # 1' for two 10-year rotations and three spac-ings, with emphasis on impacts of different interestrates, inflation and price trends, and Lake States

The effectiveness of herbicides in reducing weed compe- land use alternatives.tition (left) compared to the control (right). When largefield tests are conducted for such intensive culture The cashflows will be contrasted with energy flowspractices as weed control, the costs and effectiveness of to determine cost-energy tradeoffs. In addition, thealternative treatments can be compared, minimum operational size will be identified. The

costs and energy balances will be assessed for bio-mass on the stump, delivery of whole-tree chips at

Research Problem percent moisture content, and delivery of kiln-dried whole-tree chips.

' SRIC systems have been explored in response to

'rising land prices and taxes, increasing demands for Research Resultsrecreation and nonforest uses of forest land, escalat-•ing future fiber demands, and rising costs ofconven- Break-even analyses were prepared for each oftional energy. The system appears to offer resource eight management alternatives ranging from 2-yearmanagers the opportunity to supply the same quan- rotations with numerous coppice harvests to 15-yeartity of fiber on much less acreage and the opportunity rotations without coppicing. Low, medium, and highto grow energy feedstocks at competitive prices. An cost estimates were used for each production activityadditional significant attraction of this system is the within each of the eight management programs. Allpotential realization of an equivalent return on in- management costs were compounded to the time ofvestment with 6 to 10 years after planting, rather harvest or the end of the rotation. These are thethan the 30 to 60 years necessary for conventional minimum values that must be recovered when sell-

. silvicultural systems, ing the wood before any profit is returned.

0"

Using receni_ simulation biological growth resultsand assuming that energy from wood is worth $1.00

per million Btu's and dry fiber is worth $30.00 per ]NDUSIR]AL COO]_[__IORSton, the eight management alternatives were evalu- :ated for potential profitability. Alternatives with ro-tation ages ofl0 to 15 years, one coppice rotation, andaverage yields of 8.4 to 10.0 dry tons/acre (18.8 to 22.4mt/ha)/year total biomass, appeared potentially prof-itable .for both energy and fiber. The cost of woodproduced under 4- to 5-year rotations approached$1.00/mmBtu and $3-0.00 dry ton only where lowmanagement costs were assumed. In general, theanalysis suggests that the longer rotations will bemore profitable than extremely short ones.

Because.production costs are different between thefirst harvesting period .and the following coppicings,the time required to recover the investment, i.e.,when compounded yields exceed compounded ex- Populus grows well on sandy sites irrigated withpenditures,-is also an important consideration. The secondary pulp mill effluent.farther, into the future the payback occurs frominitie/1 point, the greater the risk of the investmentand the more important the success of scheduled Research Problemc°ppicings" Industry will ultimately determine the commer-

Evaluating the sensitivity of total production costs cial success of intensive culture concepts. Some of theto changes in various cost factors provides considera- intensive culture techniques developed under re-

'ble information for setting research priorities. Em- search conditions may not be feasible in large indus-phasis should be placed on cultural practices that will trial woodlands programs. Therefore, it is extremelym0st decrease the total production costs if their costs important to cooperate with industrial foresterswere decreased. For example, a $10/acre decrease infertilizer cost would decrease the cost of energy by throughout the research and development effort.

$0.20/mmStu; a $10/acre decrease in harvest costs Research Objectiveswould decrease the cost of energy by $0.15/mmBtu;and-a $10/acre decrease in first-year establishment The technical and economic feasibility of intensivecosts would decrease energy costs by $0.08/mmBtu. culture cannot be determined by small field experi-This result suggests that costs could be significantly ments such as those conducted at Rhinelander. Largereduced if fertilizer requirements were decreased by plantations must be established to learn whetherplanting nitrogen-fixing cover crops, alder, or other research results can be applied in industrial forest

. .nitrogen-fixing tree species, operations and to obtain information about the cost of

" . More detailed economic evaluations using cash- operational intensive culture systems., flow.analyses are in progress. Operational informa-

tion on machine production rates, man-hours, andfuel consumption rates have been collected from the More than 30 million gallons of effluent are produced

• daily by a large modern paper mill in the Lake States., large-scale planting s at the Harshaw farm near Currently, holding ponds are used for biological treat-

Rhinelander, Wisconsin. Data will also be available ment of wastes before discharge into a river.from the pilot-sized intensive culture system nowestablished, in the Lake States. Costs and energy

requirements have been compiled for the purchaseand maintenance of equipment, and the cost curvesand energy inputs for alternative equipment combi-nations are being developed.

21

Research Results

One Of the pulp mills in the Lake States has beenexploring the possibility of using mill effluent from asecondary treatment plant as an irrigating mediumon trees growing on land adjacent to the mill. Thecompany is interested in obtaining uniform highquality wood and in reducing transportation costs,

harvesting costs, and taxes on vast acreages of forestland:

Moreover, the company is concerned about devel-oping a means of disposing of some 30 million gallons

o.f effluent a day, which is presently treated and thendischarged into a river. One possible use for thiseffluent is irrigation of intensive culture trees. Inareas of the united States where water is limited and

industrial plants have to find a way, to dispose ofeffluent, irrigation with treated effluent may be a 4solution to both problems. _......

A large-scale pilot study is in progress to test the ....most intensive methods for growing fiber. A 40-acresite has been cleared, and tilled, and Populus cut-tings will be planted at two spacings. An irrigationsystem to distribute the effluent will be installed to

" maintain an optimum moisture regime for the trees.•In addition, a 1-acre test plot of willow (Salix) andseveral Populus clones has been established to

determine the tolerance of these species to high ap-•plications of effluent and the effect of the effluent ongroundwater quality.

The groundwater at the site has been thoroughlymapped to identify depth, direction of flow, andchemical nature. Throughout the study it will bemonitored to detect changes due to irrigation withthe effluent.

Water sampling probes are used to monitor the ground-" water quality under and near the site where effluent is

being applied.

Wastewater effluent from the pulp mill holding ponds(top) is pumped (middle) to the experimental fields.There, it is applied onto the intensive culture Populuswith a flood irrigation system (bottom). Flood irrigationis used to avoid the possible odor problems of overheadspraying.

:22

As a separate effort, more than 1,200 acres of Popu- _,_o_...... ":lus and A lnus were planted in 1978 by the Packaging °_ =:

Corporation of America near Manistee, Michigan, in _ ,cooperation with the Maximum Yield Program. :_,Nurseries of superior clonal material were estab-lished and hardwood cuttings were planted in 3.3 x

3.3 m .spacings. Agricultural techniques and equip-ment were used to mechanically prepare the site,

fertilize, and cultivate. Smaller acreages were estab-

I lished during the previous 3 years, with considerable•failure due to stand establishment problems and

I weed competition. Successful cultural practices formany of these problems have gradually been worked Commercial agricultural equipment is used for site

_' out and survival of trees for 1978 was more than 80 preparation. In some fields, the mills'sewage sludge was

percent. It-is expected that an additional 1,200 acres applied to provide soil amendments.Willbe established in 1979.

° ' "_ G

At the Packaging Corporation of Arnerica plantations, a20-foot cultivator is used to clean three rows of Populus

Large plantings have been established by Packaging at one time. About 100 acres can be cultivated dailyCorporation of America to obtain operational and during the first growing season.

economic information about meeting their mill needs Some of the older plantings are growing well, par-with, intensively cultured Populus. ticularly this stand of 2-year-old Populus. Wide spacings

were used because the trees will be grown for lO-to 15-year rotations.

= _ _,. _,_

• °

°

23

°

Dawson, David H. 1973. Rust resistance of Populusclones compared in Wisconsin study. Tree Plant-

___C__O_S er's Notes 25(1):16-18.

Dawson, David H. 1975. Are cultural methods avail-able to maximize yields. Iowa State Journal ofResearch 49(3, 2 pt.):279-280.

Dawson, David H. 1975. A program to develop maxi-

This list includes all publications since 1970 of the mum wood yield from planted stands. Popl.ar Coun-Maximum Yield of Wood and Energy Research and cil News, Fall, 1975:4-5.Development Program, North Central Forest Exper- Dawson, David H. 1976. History and organization ofiment Station, U.S. Department of Agriculture, Multiproject Program II. In Intensive plantation

Forest Service. culture-- five years research. U.S. Department ofAgriculture Forest Service, General Technical Re-

Crist, John B. 1976. Utilizatio_ advantages of mate- port NC-21, p. 1-4. U.S. Department of AgricultureForest Service, North Central Forest Experimentrial produced in maximum fiber yield plantations.

In Intensive Plantation Culture. U.S. Department Station, St. Paul, Minnesota.of Agriculture Forest Service, General Technical Dawson, David H. [n.d. Circa 1976.] New intensiveReport NC-21, p. 109-111. U.S. Department of Ag- culture systems in the Lake States. In Intensivericulture Forest Service, North Central Forest forest management Conference Proceedings, Uni-Experiment Station, St. Paul, Minnesota. versity of Minnesota, Cloquet Forestry Center,

Crist, John B., and David H. Dawson. 1975. Anatomy Cloquet, Minnesota. March 1975, p. 71-74, 74-75.and dry weight yields of two Populus clones grown Agricultural Experiment Station, Miscellaneousunder intensive culture. U.S. Department of Agri- Report 136.

. culture Forest Service, Research Paper NC-113, 6 Dawson, David H., and John Crist. [n.d. Circa 1972.]p. U.S. Department of Agriculture Forest Service, Dry weight yields and wood anatomy of twoNorth Central Forest Experiment Station, St. Populus clones after two seasons of intensive cul-Paul, Minnesota. ture. Sixth TAPPI Forest of Biology Conference

Crist, John B., David H. Dawson, and JoAnn A. Nel- [Abstract], May 1-3, 1972, Appleton, Wisconsin III-son. 1976. Wood and bark quality of juvenile jack 3"1-2.pine and eastern larch grown under intensive cul- Dawson, David H., and Jay G. Hutchinson. 1972.ture. In 1977 TAPPI Forest Biology Wood Chemis- Research tackles the pulpwood generation gaptry Conference, Madison, Wisconsin. p. 211-216. through maximum fiber yield program. Forest

Crist, John B., and Dean W. Einspahr. [In press.] Industry 99(2):26-27.Kraft pulp and paper properties of whole-tree, Dawson, David H., and Jay G. Hutchinson. 1973.short rotation intensively cultured jack pine and Farming for Fiber. Wisconsin Conservation Bulle-eastern larch. In 33rd Annual Meeting, Forest tin 38(3):24-26.

Products Research Society Proceedings. San Fran- Dawson, David H., Judson G. Isebrands, and John C.cisco, California. July 8-12, p. 5 (Abstract). Gordon. 1976. Growth, dry weight yields, and spe-

Crist, John B., Judson G. Isebrands, and Neil D. cific gravity of 3-year-old Populus grown underNelson. 1979. Suitability of intensively grown Pop- intensive culture. U.S. Department of Agricultureulus raw material for industry. 16th North Ameri- Forest Service, Research Paper NC-122, 7 p. U.S.

' can Poplar Council Proceedings. Thompsonville, Department of Agriculture Forest Service, NorthMichigan. p. 65-74. Central Forest Experiment Station, St. Paul,

•Crist, John B., Judson G. Isebrands, J. D. Sinkey, and Minnesota.W. L. Bohn. 197.8. Thermo-mechanical pulping of 3short-rotation intensively cultured species. An- Dawson, David H., and Nonan Noste. 1976. Review ofnual Meeting, Forest Products Research Society competition control for intensive culture forestryProceedings, Atlanta, Georgia. June 25-29, 1978, in the north central Region. Iowa State Journal ofp. 21. (Abstract). Research 50(3):271-275.

Dawson, David H. 1971. Maximizing fiber yields Dawson, David H., and Howard M. Phipps. 1978.from woody species. American Pulpwood Associa- Vegetative propagation of Populus for intensivelytion Technical Paper, January 1972, p. 9-16. cultured plantations, p. 8-22. In Fourth North

24

American Forest Biology Workshop Proceedings, Hansen, Edward A. 1977. Forest irrigation: a review.August 9-11, 1976, SUNY, Syracuse, New York. In Soil moisture...site productivity Symposium

Dawson, David H. Jaroslav Zavitkovski, and Judson Proceedings. Myrtle Beach, South Carolina. p.' 126-137.G. Isebrands. 1978. Managing forests for maxi-mum yields. In Second Annual Symposium on Hansen, Edward A., and James B. Baker. 1979.Fuels fromBiomassProceedings, June 20-22, Troy, Biomass and nutrient removal in short rotationNew York. p. P-161 to P-167. intensively cultured plantations. In Proceedings

Symposium on Impact of Intensive Harvesting on.Dickson, Richard E., and Philip R. Larson. 1977. Forest Nutrient Cycling. p. 130-151.

Muka from Populus leaves: a high-energy feed sup-plement for livestock. In Eighth TAPPI Forest Hansen, Edward A., and Richard E. Dickson. 1979.• Water and mineral nutrient transfer between rootBiology Wood Chemistry Conference, p. 95-99.

systems of juvenile Populus. Forest ScienceJune 201-22,Madison, Wisconsin: 25(2):247-252.

Dykstra, Gary F. 1974. Nitrate reductace activity Hansen, Edward A., Howard M. Phipps, and Davidan d protein concentration of two Populus clones. H. Tolsted. 1979. Rooting greenwood tip cuttings ofPlant Physiology 53:632-634. a difficult-to-root Populus clone. Tree Planters

Ek; Alan R. 1_79.. A model for estimating breinch Notes 30(2):9-11.

Weight and branch leaf weight in biomass studies. Hansen, Edward A., H. A. McMeel, D. A. Metzer, H.Forest Science 25:303-306. A. Phipps, P. S. Roberts, Terry Strong, David

Ek, Alan R., and David H. Dawson. 1976. Actual and Tolsted, and J. Zavitkovski. 1979. Short rotationprojected growth and yields ofPopulus 'Tristis # 1' intensive culture practices for northern Wisconsin.under intensive culture. Canadian Journal of For- 1979. In 16th Annual Meeting Proceedings. Northest Research 6(2):132-144. American Poplar Council. August 14-17, 1979,

Ek, Alan R., and David H. Dawson. 1976. Yields of Filer City, Michigan. p. 47-63.intensivelygrown Populus: actual and projected. Isebrands, J. G. 1977. Short rotation silviculture asIn Intensive_ plantation culture_five years re- an energy source. Proceedings National Con-search. U.S. Department of Agriculture Forest ference Forest Products Utilization Research,Service, General Technical Report NC-21, p. 5-9. Madison, Wisconsin, October 25-27, 1977. p. 18.U.S. Department of Agriculture Forest Service, (Abstract).

North Central Forest Experiment Station, St. Isebrands, J. G., and N. D. Nelson. 1979. DistributionPaul, Minnesota. of number of leaves and leaf area in short rotation

Geimer, Robert L. 1976. "Agricultural" poplars as a intensively cultured Populus 'Tristis'. Proceedingsraw material for structural particleboard. In In- 5th North American Forest Biology Workshop,tensive plantation culture--five years research. Gainesville, Florida, March 13-15, 1978, p. 426U.S. Department of Agriculture Forest Service, (Abstract).

General Technical Report NC-21, p. 115-117. U.S. Isebrands, J. G., and R. A. Parham. 1978. On theDepartment of Agriculture Forest Service, North nature of surface dislocations on Populus tensionCentral Forest Experiment Station, St. Paul, wood fibers. Planters Science Conference Proceed-Minnesota. ings, Blacksburg, Virginia, June 25-30, 1978,

Geimer, R. L., and J. B. Crist. 1978. Structural flake- Botany Society, American Miscellaneous Series. board fromshort-rotation intensively cultured hy- Publication 156, p. 34. (Abstract). Also IAWA

bricl poplar clones. [Abstract.] In Forest Products Bulletin 1978/2-3:47.

Research Society Annual Meeting Proceedings, Isebrands, J. G., L. C. Promnitz, and D. H. Dawson.June 25-30, Atlanta, Georgia, p. 9-10. 1977. Leaf area development in short rotation in-

Hansen, Edward A. 1976. Determining moisture- tensively cultured Populus plots. In TAPPI Forestnutrient requirements for maximum fiber yield. In Biology/Wood Chemistry Conference Proceedings,Intensive plantation culture--five years research. Madison, Wisconsin. p. 201-210.U.S. Department of Agriculture Forest Service, Isebrands, J. G., L. C. Promnitz, and David H. Daw-

I

I General Technical Report NC-21, p. 43-46. U.S. son. 1977. Leaf area development in short rotationDepartment of Agriculture Forest Service, North intensive cultured Populus plots. In 1977 TAPPICentral Forest Experiment Station, St. Paul, Forest Biology Conference. June 20-22, Madison,Minnesota. Wisconsin. p. 201-209.

25

Isebrands, J. G., J. A. Sturos, and J. B. Crist. 1979. Netzer, Daniel A., and Nonan V. Noste. 1978. Herbi-Alternatives for the integrated utilization of short cide trials in intensively cultured Populus planta-rotation intensively cultured Populus raw mate- tions in northern Wisconsin. U.S. Department ofrial, In Proceedings TAPPI Annual Meeting, Agriculture Forest Service, Research Note NC-March 12-14, New York, New York. p. 181-187. 235, 4 p. U.S. Department of Agriculture Forest

Isebrands J. G., J. A. Sturos, and J. B. Crist. Service, North Central Forest Experiment Station,1979. Integrated utilization of biomass. TAPPI St. Paul, Minnesota.62(7):67-70. Neuman, Ronald D. 1976. Pulp and paper character-

Larson, P. R., R. E. Dickson, and J. G. Isebrands. istics of Populus hybrids. In Intensive plantation1976. Some physiological applications for inten- culture_five years research. U.S. Department ofsive culture. In Intensive plantation culture--five Agriculture Forest Service, General Technicalyears research. U.S. Department of Agriculture Report NC-21, p. 112-114. U.S. Department of Ag-Forest Service, General Technical Report NC-21, riculture Forest Service, North Central Forestp. 10-18. U.S. Department of Agriculture Forest Experiment Station, St. Paul, Minnesota.Service, North Central Forest Experiment Station, Nienstaedt, Hans, and Richard M. Jeffers. 1976. In-

° _St. Paul, Minnesota. creased yields of intensively managed plantations

Michael; D., D. Dickmann, and N. Nelson. 1979. of improved jack pine and white spruce. In Inten-Photosynthesis, CO2 compensation and stomatal sive plantation culture_five years research. U.S.conductance of young poplar plants grown under Department of Agriculture Forest Service, Gen-intensive cultUre. Plant Physiology Annual Meet- eral Technical Report NC-21, p. 51-59. U.S. De-ing Supplement (Abstract). [In press.] partment of Agriculture Forest Service, North

Myers, Wayne, Louis F. Wilson, and John Bassman. Central Forest Experiment Station, St. Paul,1976. Impact of insects on trees planted for maxi- Minnesota.mum fiber production_studies in progress. In In- Noste, Nonan V., and Howard M. Phipps. 1978. Her-

. tensive plantation culture--five years research, bicide and container system effects on survival andU.S. Department of Agriculture Forest Service, early growth of conifers in northern Wisconsin.General Technical Report NC-21, p. 92-95. U.S. The Forestry Chronicle 54(4):209-212.Department of Agriculture Forest Service, NorthCentral Forest Experiment Station, St. Paul, Pallardy, S. G., and T. T. Kozlowski. 1979. Relation-

ships of leaf diffusion resistance of Populus clonesMinnesota. to leaf water potential and environment. Ecologia

Nelson, N. D., and W. E. Hillis. 1978. Association 40:371-380.

between altitude and xylem ethylene levels in Eu- Pallardy, S. G., and T. T. Kozlowski. 1979. Stomatalcalyptus pauciflora. Australia Forest Research response of Populus clones to light intensity8:69-73. and vapor pressure deficit. Plant Physiology

Nelson, N. D., and W. E. Hillis. 1978. Ethylene and 64:112-114.

tension wood formation in Eucalyptus gomphoce- Parham, R. A., K. W. Robinson, and J. G. Isebrands.•: phala. Wood Science Technology 12:309-315. 1976. Effects of tension wood on kraft paper from a

Nelson, N. D., and W. E. Hillis. 1978. Genetic and short rotation hardwood (Populus Tristis #1).biochemical aspects of kino vein formation in Eu- Institute of Paper Chemistry IPC Technologycalyptus I. Genetic variation in response to kino Series _40, p. 15.

induction in E. regnans. Australia Forest Research Parham, R. A., K. W. Robinson, and J. G. Isebrands.8:75-81.1977. Effects of tension wood and kraft paper from

Nelson, N. D., and W. E. Hillis. 1978. Genetic and a short rotation hardwood (Populus Tristis #1).biochemical aspects of kino vein formation in Eu- Wood Science and Technology 11:291-303.:calyptus II. Hormonal influences on kino formationin E. regnans. Australia Forest Research 8:83-91. Petersen, Larry A., and Howard M. Phipps. 1976.

Water soaking pretreatment improves rooting andNelson, N. D., J. G. Isebrands, and W. E. Hillis. 1978. early survival of hardwood cuttings of some Popu-

Some effects of ethylene on the morphology and lus clones. Tree Planter's Notes 27(1):12, 22.anatomy of Eucalyptus and Populus seedlings.(Abstract) Plant Science Conference Proceedings, Phipps, Howard M. 1976. Propagation research inBlacksburg, Virginia, June 25-30, 1978. Botany the establishment of maximum yield plantations.Society America, Miscellaneous Series Publication In Intensive plantation culture_five years re-156, p. 34. Also IAWA Bulletin 1978/2-3:48. search. U.S. Department of Agriculture Forest

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Service, General Technical Report NC-21, p. 60-62. plantation culture--five years research. U.S. De-U.S. Department of Agriculture Forest Service, partment of AgriCulture Forest Service, GeneralNorth Central Forest Experiment Station, St. Technical Report NC-21, p. 81-84. U.S. Depart-Paul, Minnesota, ment of Agriculture Forest Service, North Central

Phipps, Howard M. 1977. White spruce seedlings re- Forest Experiment Station, St. Paul, Minnesota.spond to density and fertilizer treatments in a plas- Schipper, Arthur L., Jr., and David H. Dawson.tic greenhouse. Tree Planter's Notes 28(1):8-10, 38. 1974. Poplar leaf rust---a problem in maximum

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PhipPs'HowardA. 1978. Rooting Populus cuttings in wood fiber production. Plant Disease Reporter.Various media bound with a liquid polymer. Plant 58(8):721-723.Propagator 24(2):11-13. Schipper, Arthur L., Jr., Harold S. McNabb, Jr., and

Phipps, Howard M., Dana A. Belton, and Daniel A. William F. Haywood. 1977. Dothichiza and Pho-Netzer. 1977. Cutting propagation of some Populus mopsis cankers of hybrid poplar in Iowa. (Abstractclones for tree plantations. Plant Propagator 128) American Phytopathology Society Proceed-23(4):8-11. ings 4:109-110.

Phipps, Howard M., and Nonan V. Noste. 1976. Some Strong, Terry F., and J. Zavitkovski. 1978. Morphol-' problems of establishing and managing inten- ogy of jack pine and tamarack needles in dense

Sively cultured planted stands. In Intensive stands. U.S. Department of Agriculture Forestplantation culture--five years research. U.S. De- Service, Research Paper NC-153, 6 p. U.S. Depart-partment of Agriculture Forest Service, General ment of Agriculture Forest Service, North CentralTechnical Report NC-21, p. 47-50. U.S. Depart- ForestExperiment Station, St. Paul, Minnesota.ment of Agriculture Forest Service, North Central Sturos, J. A., J. B. Crist, J. G. Isebrands, N. D. Nel-Forest Experiment Station, St. Paul, Minnesota. son. 1978. Harvesting and benefication of whole-

tree chips from three short rotation, intensivelyPromnitz, Lawrence C., and Paul H. Tray. 1976. cultured species. (Abstract). In FPRS Annual. Rapid selection techniques for indentifying supe- Meeting Proceedings, p. 5. Atlanta, Georgia. June

rior clones. In Intensive plantation culture--five 25-30, 1978.years research. U.S. Department of AgricultureForest Service, General Technical Report NC-21, Sucoff, Edward, and Dennis Hiesey. 1978. Pre-p. 25-31. U.S. Department of Agriculture Forest liminary evaluation of leaf water potential forService, North Central Forest Experiment Station, irrigating hybrid poplar. Minnesota AgricultureSt. Paul, Minnesota. Experiment Station, Science Journal Series Paper

10264, and Fifth North American Forest BiologyRose, Dietmar W. 1975. Fuel forest vs. strip-mining:

fuel production alternatives. Journal of Forestry Workshop Proceedings, p. 187-195.•73(8):489-493. Widin, Katherine D., and Arthur L. Schipper, Jr.

Rose, Dietmar W. 1976. Economic investigations of 1976. Epidemiology and impact of Melampsora me-intensive silvicultural systems. Iowa State Jour- dusae leaf rust on hybrid poplars. In Intensivehal of Research 50(3):301-315. plantation culture--five years research. U.S. De-

Rose, _Dietmar W. 1977. Cost of producing energy partment of Agriculture Forest Service, Generalfrom wood in intensive cultures. Journal of Envi- Technical Report NC-21, p. 63-74. U.S. Depart-

ronmental Management 5:23-35. ment of Agriculture Forest Service, North CentralForest Experiment Station, St. Paul, Minnesota.

Rose, Dietmar W., and Dean S. DeBell. 1978. Eco-nomic assessment of intensive culture of short- Widin, K. D., and A. L. Schipper, Jr. 1977. Develop-rotatioh hardwood crops. Journal of Forestry ment of the uredium ofMelampsora medusae. (Ab-76(11):706-711. stract 127) American Phytopathology Society

Schipper, Arthur L., Jr. 1976. Hybrid poplar diseases Proceedings 4:109.anddisease resistance. In Intensive plantation cul- Widin, K. D., and A. L. Schipper, Jr. 1978. Melamp-ture--five years research. U.S. Department of Ag- sora medusae affects hybrid poplar growth in thericUlture Forest Service, General Technical Report north-central USA. (Abstract 055). In 3rd Interna-NC-21, p. 75-80. U.S. Department of Agriculture tional Congress Plant Pathology Proceedings.Forest Service, North Central Forest Experiment p. 130. August 16-23, 1978, Munchen, FederalStation, St. Paul, Minnesota. Republic of Germany.

Schipper, Arthur L., Jr. 1976. Poplar plantation Tray, P. H., and L. C. Promnitz. 1976. Controlleddensity, influences foliage disease. In Intensive environment selection of Populus clones. In Inten-

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sive plantation culture--five years research. U.S. intensively cultured jack pine plantations in Wis-Department of Agriculture Forest Service, Gen- consin. U.S. Department of Agriculture Foresteral Technical Report NC-21, p. 25-31. U.S. Service, Research Paper NC-157, 15 p. U.S. De-Department of Agriculture Forest Service, North partment of Agriculture Forest Service, NorthCentral Forest Experiment Station, St. Paul, Central Forest Experiment Station, St. Paul,Minnesota. Minnesota.

Zavitkovski, J. 1976. Biomass studies in intensively Zavitkovski, J., and David H. Dawson. 1978. Struc-managed forest stands. In Intensive plantation ture and biomass production of 1- to 7-year-oldculture--five years research. U.S. Department of intensively cultured tamarack plantations inAgriculture Forest Service, General Technical Wisconsin. In 1978 TAPPI Annual Meeting Pro-Report NC-21, p. 32-38. U.S: Department of Agri- ceedings, p. 29-35. Chicago, Illinois.

culture Forest Service, North Central Forest Ex- Zavitkovski' J., and David H. Dawson. 1978. Inten-periment Station, St. Paul, Minnesota. sively cultured plantations. Structure and biomass

Zavitkovski, J. [In press]. Biomass farms for energy production of 1- to 7-year-old tamarack in Wiscon-production: an analysis of biological consideration, sin. TAPPI 61(6):68-70.

In Society of American Foresters Annual Meeting Zavitkovski, J., Edward A. Hansen, and H. A.Proceedings. October 23-25, St. Louis'. McNeel. 1979. Nitrogen-fixing species in short ro-

Zavitkovski, J. 1979. Energy production in irrigated, tation systems for fiber and energy production. Inintensively cultured plantations ofPopulus 'Tristis Symbiotic Nitrogen Fixation in the Management#1' and jack pine. Forest Science 25(3):383-391. of Temperate Forests Symposium Proceedings,

Zavitkovski, J., and David H. Dawson. 1977. Biomass April, Corvallis, Oregon. [In press.].distribution in 6-year-old intensively culturedjack Zavitkovski, J., J. G. Isebrands, and D. H. Dawson.pine plantations in northern Wisconsin. In 1977 1977. Productivity and utilization potential ofTAPPI Forest Biology-Wood Chemistry Confer- short-rotation Populus in the Lake States. In East-ence Proceedings, p. 217-221, Madison, Wisconsin. ern Cottonwood and related species Symposium

Zavitkovski, J., and David H. Dawson. 1978. Struc- Proceedings. Greenville, Mississippi, Septemberture and biomass production of 1- to 7-year-old 28-October 2, 1976, p. 392-401.

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28 -_ U. S.GOVERNMENT PRINTING OFFICE: 1980 669-208

U.S. Department of Agriculture, Forest Service.1980. Energy and wood from intensively cultured plantations: research

and development program. U.S. Department of Agriculture ForestService, General Technical Report NC-57, 28 p. U.S. Department ofAgriculture Forest Service, North Central Forest Experiment Sta-tion, St. Paul, Minnesota.

Since 1971 there has been significant progress in greatly increasingyields of wood and energy (biomass) from intensively cultured planta-tions compared with natural stands. This publication reports theresults of studies and summarizes the "maximum-yield" research inprogress at the North Central Forest Experiment Station.

KEY WORDS: biomass, maximum-yield, short rotation-forestry,physiology, tree-planting.

U.S. Department of Agriculture, Forest Service.1980. Energy and wood from intensively cultured plantations: research

and development program. U.S. Department of Agriculture ForestService, General Technical Report NC-57, 28 p. U.S. Department of

• Agriculture Forest Service, North Central Forest Experiment Sta-tion, St. Paul, Minnesota.

Since 1971 there has been significant progress in greatly increasingyields of wood and energy (biomass) from intensively cultured planta-tions compared with natural stands. This publication reports the /

• results of studies and summarizes the "maximum-yield" research in• .

progress at the North Central Forest Experiment Station.

KEY WORDS: biomass, maximum-yield, short rotation-forestry,physiology, tree-planting.

\

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