Temporate Agroforestry: NC-RWU-4154PROBLEM 12.15

Adaptive and Mitigative roles in AvVMAILAR/wBLF_EAR

AChanging Physical and Socio-Economic Climate

Proceedings of the Seventh Biennial Conference on Agroforestry in North America

and

Sixth Annual Conference of the Plains and Prairie Forestry Association

August 12 - 15, 2001

William Schroeder and John Kort, Editors

4

Grossman, Benjamin C.; Gold Michael A.; Dey, Daniel C. [2001].Restoration of hard mast species for wildlife in Missouri

floodplains: precocious flowering in Quercus. In: Schroeder,William; Kort, John, eds. 7thbiennial conference on agroforestry inNorth America and 6thannual conference of the Plains and Prairie

Forestry Association; 2001 August 12-15; Regina, Saskatchewan,Canada. [City, State: Publisher unknown]: 233-242.

Temperate Agroforestry:Adaptive and Mitigative Roles in

A Changing Physical and Socio-Economic Climate

Proceeding of the Seventh Biennial Conference on Agroforestry in North Americaand

Sixth Annual Conference of the Plains and Prairie Forestry Association

August 13 - 15, 2001Regina, Saskatchewan, Canada

William Schroeder and John Kort, Editors

iii

Table of Contents

CHAIRMAN'S MESSAGE ii

KEYNOTE ADDRESSESAgroforestry as a Carbon Sink 2

R. Neil Sampson

Poplar as a Crop -It's Place in a ChangingAgriculture ........................... ; ............ 9Brydon Ward

Shelterbelts: Their Place in a Changing Agriculture .......................................... 12Bruce C. Wight

Agroforestry Technology Transfer and Outreach: Where Do We Go From Here? ................... 19Sandra S. Hodge

Agroforestry Research and Development in North America: Environmental Benefits and Potentials .... 25Andrew M. Gordon and Naresh V. Thevathasan

•CONCURRENT SESSIONS

Greenhouse GasesThe Carbon Sequestration Potential of Prairie Shelterbelts and Their Contribution to a NationalGreenhouse Gas Mitigation Stragegy ..................................................... 27

Bob Tumock

Above and Below-Ground Biomass Production by Two-Year-Old Poplar Clones on FloodplainSites in the Lower Midwest, U.S.A......................................... .............. 34

S. G. Pallardy, D.E. Gibbins and J.L Rhoads

An Economic Analysis of Fossil Fuel Substitution for Climate Change Mitigation 40Peter J. Graham

Impacts of Drought on Growth and Regeneration of Conifers on the Canadian Prairies .............. 46E.H. (Ted) Hogg

Response of Tembling Aspen and Hybrid Poplar to CO2Enrichment in the Greenhouse ............. 52Kendall A. Tupker, S. Ellen Macdonald and Barb R. Thomas

Stragegies for Improved Establishment of Conifers on Marginal Lands on the Canadian Prairies ...... 68P.A. (Rick) Hurdle, Dan Maclsaac and Graham Hillman

Biomass and Taper Equations for Hybrid Poplar Growing in SRIC Plantations and Estimatesof C Contained in A'boveground Biomass .................................................. 69

L.M. Zabek, C.E. Prescott and C. van Oosten

Understanding the Role of Risk Perception and Attitudes in Climate Change Policy-Making .......... 70Adam Wellstead

_iv

Socio-Economic IssuesAdapting Agroforestry Extension Programs to the Area: A Survey of Central Minnesota Farmerand Extension Educators " 72

Michael Demchik

Extent and Geographic Location of Agroforestry Throughout the US - an RC&D Survey 77Richard•Straight

Agroforestry in the Southeastern United States: Current Practices and Potential for Development ..... 81Sarah W. Workman, Michael E. Bannister and P.K.R. Nair

Economic Differences Between Agriculture and Agroforestry ................................... 94Larry D. Godsey

Overview of Agroforestry Practices in Central Brazil ........................................ 101Wayne A. Geyer, Francis Dube and Laercio Couto

The Forest Garden 103 :Gregoire Lamoureux

Evolution of an Agroforestry Program•- The Road From Self-Interest to Common Ground 107Shane Tornblom

Federal Support for Agroforestry Research: The USDA Cooperative State Research, Educationand Extension Service's Share • 108

Catalino A. Blanche and Larry Biles

Silvopasture SystemsGrazing Cattle in a Black Walnut Agroforestry System ...................................... 110

Larry Harper

Tree-Pasture Species Interactions in a Silvopastorai Experiment in New Zealand ................. 114Donald J. Mead and Scott X. Chang

Forage Frost Protection Within Conifer Silv0pastures ....................................... "i20CoM.Feldhake

Effect of Shade on Forage Quality ...................................................... 125M.B. Huck, M.S. Kerley, H.E. Garrett, R.L. McGraw, J.W. Van Sambeek andN.E. Navarrete-Tindall

Grazing During the Establishment Period: Methods of Tree Protection and Impact of Grazing onTree and Animal Performance ................................ ......................... ;I35

J.W. Lehmkuhler, E.E.D. Felton, D.A. Schmidt, K.J. Bader, A. Moore, M.B. Huck, H.E. Garretand M.S. Kerley

Forageand Livestock Production From a Winter Annual Forage System in a Silvopastoral Setting .... 144R.L. Kallenbach, M.S. Kerley, G.J. Bishop-Hurley

Groundwater Nitrogen Dynamics in a Temperate Alley Cropping System With Pecan(caryafllinoensis) and Cotton (gossypium sp.) " 145

Samuel C. Allen, Shibu Jose and P.K.R. Nair

Stacked Broiler Litter Impacts the Biological and Financial Productivity of Loblolly PineSilvopastures ........... ............................................................ 146

Terry R. Clason

Ponderosa Pine Silvopasture: A Practical Environmental Safeguard " 147Doak Nickerson

V

Intercropping/AlleycroppingDevelopment of Sea Buckthorn (Hippophae Rhamnoides L.) As an Agroforestry Crop on theCanadian Prairies ........... ......................................................... 149

Pare Franklin, W.R. (Bill) Schroeder and Sakti Jana

Economics of a Commercial Alley Cropping System in Central Brazil ........................... 153FoDube, WA. Geyer and L. Couto

Management Challengesof Temperate Alley Cropping Systems: Lessons from SouthernU.S.A ...... 158Craig Ramsey and Shibu Jose

Intensive Intercropping in Orchard Agriculture - An Extension Report ........................... 164Todd Leuty

Arthropod Dynamics in Monocropped and Black Walnut - Alley Cropping Forages ................ 167W. Ter?eflStamps, Terry L. Woods and Marc J. Linit

Transforming Agroforestry Plantings to On-Farm Profit Centers Through Specialty Forest ProductProduction ...... ............................ _........................................ 170

Scott J. Josiah, David Lambe, Richard St. Pierre and Rachel Allison

Development of Juneberry as an Agroforestry Crop in North Dakota ........................... 176M.B. Jackson, J.A. Walla and H.M. Hatterman-Valenti

A Framework to Analyze Markets for Traditional and Nontraditional Midwestern AgroforestryProducts: The Case of Eastern Red Cedar ............................................... 179

Michael A. Gold and Larry D. Godsey

ShelterbeltsEvaluation of the Break-Even Corn Yield Within the Leeward Protected Zone of a Windbreak ........ 185

Robert K. Grala and Joe P. Colletti

Impact of Weed Management Intensity on Growth of Field Shelterbelts ......................... 199Lyle Alspach and William Schroeder

Shetterbelts, Livestock Odor Mitigation, and Sustainable Agriculture: A Research Framework ....... 206John Tyndall and Joe Colletti

Evaluation of Temperature Profiles Over Crop Canopies Protected by Shelterbelts and theResponse of Soybean Crops to Temperature Modifications (preliminary results) .................. 220

G.C. Horvath, W. Mize and W.D. Batchelor

Prog[ess on Modeling Crop Production Under Shelter ...................................... 221Carl Mize, W. Batchelor, E. Takle, J. Brandle, M. Egeh and g, Horvath

Riparian Buffer Strips / PhytoremediationEstablishment of Riparian Forest Buffers on Agricultural Lands in the Oregon Coast RangeBeaver Creek Case Study ................ . _.................................... : ...... 223

Badege Bishaw, William Rogers and William Emmingham

Restoration of Hard Mast Species for Wildlife in Missouri Floodplains: Precocious Floweringin Quercus ........................................................................ 233

Benjamin C. Grossman, Michael A. Gold and Daniel C. Dey

• Financial Agents, Water Quality and Riparian Forest Buffers ................................. 243Matthew J. Brewer and Joe P. Colletti

Riparian Buffers Control Water Pollution: Need We Know More? .............................. 253Michael G. Dosskey

vi

Incorporation ofSelected Forage Grasses in Riparian Buffers Designed for the Bioremediationof Atrazine, Balance (Isoxaflutole)and Nitrate .... , ........................................ 256

C.H. Lin, R.N. Lerch, H.E. Garrett and M.F. George

Johnson Silvacycling Project - Establishment and Baseline Data Collection ...................... 266Kevin teneycke

Riparian Forest Buffers in the Agroecosystem: A Decade of Research .......................... 267Joe P. Colletti

Hybrid PoplarIrrigating Poplars with Near-Surface Ground Water ......................... _............... 269

H. Steppuhn, J. Kort and D.G. Smith

Application of DNA Markets for the Identification and Management of Hybrid Poplar Accessions ..... 276Faouzi Bekkaoui; Bruce Mann and Bill Schroeder

- Increasing Productivity of Hybrid Poplar Plantations in British Columbia Through Inorganicand Organic Fertilization -Operational Opportunities ................... . ................... 282

Cees van Oosten, Mike VanHam and Lisa Zabek

Potential Pests of Poplar Plantations in Saskatchewan ........ "............................... 288Don Reynard

Nutrition and Fertilization Response of T x D Hybrid Poplar .................................. 291L.M. Zabek and C.E. Prescott

Clonal Evaluation of Hybrid Poplaron the Canadian Prairies ................................. 298D.S. (Dan) Walker and W.R. (Bill) Schroeder

Investigating Cottonwood Biomass Production Clones for Insect Pests in a Missouri Floodplain ...... 308Allen J. Niedermann, W. -FerrellStamps and Marc J. Linit

Extensive Management of Hybrid Poplar on Coastal Flood Plains .......................... ... 309Dan Carson

POSTER PRESENTATION ...... ................................................. 310

FIELD TOUR SUMMARIES ....................................................... 330

PLANT MATERIAL TOUR ..................... i ................................. 341

PARTICIPANTS LIST ............................................................ 346

[

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RESTORATION OF HARD MAST SPECIES FOR WILDLIFE IN MISSOURI FLOODPLAINS:PRECOCIOUS FLOWERING IN QUERCUS

Benjamin C. Grossman, Michael A. Gold and Daniel C. Dey

University of Missouri Center for Agroforestry203 ABNR Building

Columbia, MO 65211

ABSTRACT

This paper details the value of and need for planting hard mast oak species in the Lower Missouri River floodplain.Additionally, it describes results from the use of Containerized root production method (RPMTM) oak seedlings for thereforestation of the Lower Missouri River floodplain. An estimated.75 percent of bottomland hardwoods have beenremovedfrom the Mississippi Alluvial PlainSincepre-setttement times. Further, natural regeneration of oak along theUpper Mississippi and Lower Missouri Rivers has been limited following major flood events in 1993 and 1995.Traditional planting methods havehad limited successdue to frequent flood events, Competitionfrom faster growingvegetation and white-tailed deer herbivory.

Floodplainforests provide a diversityof habitat forwildlife. In areas of high agricultural production, riparian forests maybe the only habitat remaining for wildlife. Late-succession tree species, such as oak, provide mast for numerousspecies of birds as well as large and small mammals.

In the Missourifloodplain, RPMTM grown oak seedlings have considerable advantages over traditional nursery stockincluding improved transplant success, ability to be fall planted, terminal tips that reach above browse height,acceleratedgrowth in thefirst year afterfall planting and precocious flowering and mast production in the 3rdor4 thyear.Establishingflood tolerant precocious oak seedlings in the floodplain provides a source of food for acorn-c0nsuming

wildlife ten to fifteen years sooner than oaks originating from natural regeneration, direct seeding or traditional bare-root planting. In addition, precocious seedlings can increase the probability of successful oak regeneration in thefuture, reducethe intensity and rateof flowof floodwater and concurrentlyprovide sitesfor sediment depos tion insteadof scour.

Keywords: floodplain, wildlife, restoration' precocious flowering, RPM, containerized seedlings, oak

INTRODUCTIONFloodplain Forests

• Forestedfloodplain habitats, once abundant in the continental United States, have been reduced by 70 to 90 percentof their Pre-Europeanextent (Bragg and Tatsch11977; Dah11990; Knutson and Klaas 1995; Nelson 1997; Nelson etal. 1998) due largely to land clearing for agriculture and the construction of dams and levees to protect valuablecropland and aid navigation. Much of the lossof hard mast SlSeciessuch as the oaks occurred in the first wave of landClearingbecausetheYwere mostcommon onthe elevated, better drained soils, and hence the prime agricultural landsin the floodplains. River channelization and improvements for flood protection haveallowed for more of the floodplainto be convertedto agriculture, and havedrastically altered river hydrology resulting in inci'eases in the frequency andduration of high intensity floods. Changes in flood regimes in the Missouri and Mississippi River systems haveadverselyaffected tree growth, increased mortality in the less flood tolerant speciessuch as pin oak (Quercus palustrisMuenchh.),and caused successional shifts in composition to more flood tolerant species in the remnant floodplainforests (Johnson et al. 1974). The abundance of species such as swamp white oak (Quercus bicolorWillld.), bur oak(Q. macrocarpa Michx.), pin oak, black walnut (Juglans nigra L.), pecan (Carya illinoensis (Wangenh.) K. Koch),shellbark hickory (C. laciniosa (Michx,f.) Loud.) and shagbark hickory (C. ovata iMill.) K. Koch) has been greatlyreduced, as has the areal extent of cottonwood (Populus deltoides Bartr. ex Marsh.), silver maple (Acer sacchafinumL.) and sycamore (Platanus occidentalis L.) forests (Bragg and Tatschl 1977; Yin and Nelson 1995;Yin et al. 1997).The loss of floodplain forests and in particular hard mast species is of concern to wildlife biologists, foresters andprivate landowners,

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Benefits of Floodplain Forests

Flood and environmentalprotection

Woody vegetationgrowingin the floodplain increases the stability of streambanks (Geyer etal. 2000), protects levees,and reducesthe negative impacts of flooding caused by scouring, deposition and infrastructuredamage (Dwyer et al.1997; Low 1994). Levee failure was especially prevalent along the Lower Missouri River during the 1993 flood,.resulting in millions of dollars in damage to agricultural crops and cropland (U.S.Army Corps of Engineers 1996). Astudy conducted,by Dwyer et al. (1997) along a 39-mile stretch of the Lower Missouri River found that as the widthof the woodycorridor between the river bankand the primary levee increased, the damage in both numbers and sizeof leveefailures decreased during the flood of 1993. They also found that 300 feetwas the minimum width necessaryfor a woody corridor,to be effective in reducing levee failures.

Beyond.floodprotection, floodplain forests can increase groundwater storage, increase soil productivity (Ribaudo etal. 1990) and reduce nutrient run-off by absorbing, filtering and transforming excess fertilizer applied to adjacentcropland (Peterjohn and Correll 1984; Sparks 1995).

Wildlife habitat

Rivers and their floodplains are among the most highly productive ecosystems in the world (Yin and Nelson 1995),providing habitat fora wide diversityof wildlife. Inthe UnitedStates, the Missouri andMississippi Rivers serve as majorcorridors formigrating birds (Sparks 1995), as well as habitat for many year-round resident wildlife species. Floodplain.forests providea diversity of habitat for many forest dwelling bird species, mammals, amphibians and reptiles (Dwyeret al. 1997;.Sparks 1995; Yin et al. 1997; Twedt et al. 1999). In landscapes dominated by agricultural production,riparian forests may be the onlyforest habitatremaining forwildlife. Differe'ntspecies of wildlife use floodplain forest.s-to varying degrees. Some wildlife use the riparian zone to fulfill all their life requirements,while others use it only aportion of thetime for critical activities such as feeding, breeding, or as escape cover. Hirsch and Segelquist (197.8)found that 90 percent of the white-tailed deer in Louisiana lived in the bottomlands even though that type of habitatonly made up 50 percent of the potential deer range in thestate.

Since the loss of the American chestnut. (Castanea dentata (Marsh.) Borkh.) due to the outbreak of Cryphonectriaparasitica in the early1900s, Quercus has become the dominant tree genus in theeastern United States (Braun 1950;Woods and Shanks 1959), and acorns have become a major food source for numerous species of birds (i.e., turkey,ruffed grouse, quail, mallards, greater and lesser prairie chicken), large mammals (i.e., white- and black-tailed deer,mule deerandblackbear) andsmall mammals (i.e., mice,squirrel, chipmunk, fox, raccoon andporcupine) (Van Dersal1938; Martinet al. 1951).

Acorns are relativelyhigh in fat and carbohydrates and are good sources of protein,vitamins, calcium and phosphorus(Goodrum et al. 1971). Numerous wildlife species require hard mast for a source of food; waterfowl using floodplainforests for wintering areas depend on hardwood mast for the bulk of their diets (Hirsch and Segelquist 1978). Somespecies of wildlife (e.g., squirrel and turkey) rely on acorns much of the year (e.g., Christisen and Korschgen 1955),while othersare more seasonal in their consumptionof acorns. In samples collected at various check stations, acornsmade Upfrom 16 to 100 percent of the rumen contents of white-tailed deer (Short et al. 1969;Goodrum et al. 1971):

The quantityof acorns produced in a season can have an effect on wildlife populations and indirectly on how wildlifeimpact othervegetation through browsing and foraging. Forexample,Korschgen (1954)noted an increase indamageto agricultural crops and forest plantations by deer in years of poor acorn production in Missouri. Similarly, wildlifepopulationscan effect acorn production. Acorn crops have been found to besignificantly correlated with small rodentpopulations, includingsquirrels and chipmunks (McShea 2000). In years of lowto moderateacorn production, wildlifecan consume nearly the whole crop. Goodrum et al. (1971) estimated that 85 poundsof acorns per acre are requiredtOsatisfythe requirements of five species of wildlife (white-taileddeer, gray squirrel, fox squirrel, turkey and bobwhitequail) for 300days. Approximately ninewhite oaks, 16 inches in diameter, would be required to produce this amountof acorns (Goodrum et al. 1971). Because acorns and other nuts are so valuable to Wildlife,restoring hard mastproduction in floodplain forests would improve the quality of wildlife habitat.

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Floodplain Restoration for Wildlife

The Great Floodof 1993degraded over 800,000 acres of croplandin the Lower Missouri River floodplain by depositingsandand scouring fields.Thousands of acres of flood-damaged lands were purchased by state and federal agenciesfromwiiling sellerssince 1993.Managers are interestedin reforestingmany of these floodplain propert es andensur ngthat the forests have the capacity to produce hard mast.

Light-seededwindblownspecies are naturallyadaptedto old-field invasion,whereas heavy-seededmastspecies, suchas oak and pecan, require a nearby seed Source (Newling 1990; Strader et al. 1994). Along the Missouri andMississippi Rivers,the regeneration of light-seed.ed,pioneer tree species such as cottonwood, willow (Safix spp.) andsilver map}e has beer) so successful that heavy-seeded, mast-producing species important for wildlife have difficultyregenerating. Hardmastspecies havehad difficulty.becomingestablished due to the intense competition from pioneertree spedies a.ndthe lush.growth of herbaceous species, their inherent slow juvenile growth, flooding and deerherbivo.ry(i_e., Buckley et al. 1998; Dalrymple 2000 pers.comm.).

Artificial:regenerationof hardmast species is neededwhere there is a lack of a local seedsource (Newling 1990; Pope1993). Artificial regeneration hastraditionally involved sowing seed or planting bare-root seedlings. Unfortunately,attempts to establish oak and other nut species inbottomland fields have often failed despite our best knowledge andefforts. Traditional methods of planting bare-root seedli.ngs or direct seeding of oak, pecan or black walnut inbottomlands has not always been successful, even with annual weed oontrol during the establishment period. Thesemethodshave not reliably produced adequately stocked forests. For example, in a survey of 4-year-old WetlandReserve Program plantings in the Mississippi Riverfloodplain, Schweitzer and Stanturf (1997) found that only 9% ofthe total reforested lafld in 13 Mississippi counties met the Natural Resources Conservation Service.requ rement forat least 125 hard mast stems per acre (309 stems per ha) in 3-year-old stands. An alternative to traditionalregeneration practices in floodplains is the use of large containerized (e.g., 3 to5 gallons) Seedlingsproduced by a

new nursery cultural system known as the root production-method iRPMTM).

ROOT PRODUCTION METHODTM

The RPMTM process used to produce large container seedlings is brieflydescribed in the Methods section. Seedlingsgrown by this method can attain heights greater than5 feet in one to two years, have basal diameters approaching1 inch, and have root systems that are 3 to 7 times the dry massand 4 to 9 times the volume of 1-0 bare-root seedlings

• (Shaw et al. 2002).

In the Upper Mississippiand Lower Missouri River floodplains, RPMTM seedlings have considerable advantages overtraditional bare-root nursery stock including (1) improved growth and survii/al, (2) large root systems that do notexperience the damage and transplant shock that bare-root seedlings do, (3) crowns that are more likely to be abovegrowing .seasonfloods, (4) a terminal shoot that is more likely to be above deer b(owse height (i.e., > 5 feet tall (1.5meters)), (5)large basalstem diameterD 0.6 inch(1.5 centimeters)]and (6) precocious flowering andmast production.

Dey et al. (2001) found that a small proportion (oneto four percent) of Quercus bicolor (Willd.) seedlings planted as18 to 2 ! month-old RPMTM stock produced sound acorns in the first two years in former cropfields along the MissouriRiver. Although we do not fully understand this early fruiting in plantsgrown by the RPM'n!process, it is not uncommonand occurs in a variety of tree, shrub and herbaceous species. Such early acorn production in oaks is phenomenalconsidering that naturally and artificially regenerated oaks require 15 to 35 years to bare fruit (Schopmeyer 1974).

Purpose and Objectives

Theoverall purpose of the research was to establish base line data on early, morphological characteristics ofbottomland oak species that may leadto precociousflowering in seedlings produced by the RPM_ process. Specificresearch objectives were twofold: 1) to determine the effect of acorn size and mass, and early seedling growth onmorphological characteristics of one-year-old seedlings propagated under the RPMTM system; and 2) to determine ifRPMTM seedlingsfrom a wetland population of oak hybrids that exhibited early and abundant acorn.production wouldperform better than RPMTM seedlings from a randomly selected population of acorns.

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MATERIALS AND METHODS

Acorns were collected in the fall of 1999 from two separate sources. One population consisted of randomly collectedQuercusbicolor(WiIId.) acorns from Saline County, Illinois. The other acorns originatedfrom LincolnCounty, Missouriandwere from a population of half-sibling Q. bicolorx macrocarpa (Michx.), i.e., Q. x. schuettei (Trel.). In the normalRPMTM process, acorns are graded by mass and diameter. Only the heaviest and largest acorns are stratified overthe winter. In February, acorns are germinated in heated greenhouses in mesh-bottomed trays that allow for airpruning of the roots. Following the first shoot flush, seedlings are graded by precocious shoot growth and only the

• fastest growing seedlings (approximately the tallest 50 percent of germinates) continue in the RPMTM •process. Aftera series of transplants into increasingly larger bottomlesscontainers, seedlings are finally potted in shallow 3-or 5-gallon pots with a growth medium of dce hulls, pine bark and sand that has 35 percent air space. Seedlings arethenplaced outside for the remainder of the growing season. Typical RPMTM seedlings attain heights of 4 feet (1.2m) ortaller after 210 days of growth and they develop dense, fibrous rootsystems high on the root collar."

For this research, acorns were propagated into seedlings following the RPMTM process with the following importantexceptions: as acorns and seedlings were graded, all seed and plant materials were separated and retained in theirrespective size classes instead of being discarded (i.e., both large and small seed, heavy and light seed, andprecocious and non-precocious seedlings were retained). This resulted in eight treatments that represent allcombinations of acorn mass (heavy or light), acorn size (large or small) and shoot growth (precocious or not). Dueto poor germination we had fewer than expected seedlings for some treatments and were forcedto use two differentexperimental designs for each population. A 3x3 balanced lattice square design was used to examine all eighttreatments. The Q. x. schuettei population had four replications, each observation being the mean of two seedlingswithin a block. The Q. bicolorpopulation also had four replications, but had fewer seedlings due to poor germinationland therefore, each observation Wasfrom one seedling. A 4x4 balanced Latin square design was usedwith only thefour precocious treatments with one replication per population. Each block within each design contained threeseedlings, from which a statistical mean was derived to obtain one observation.

At the end of the growing season, seedlings were destructively sampled and measurements were taken on seedlingcharacteristics. Variables measured included root collar diameter (measured 2.5 cm above the root collar), height,root volume, root, shoot and total dry mass and number of flushes. Root volume was measured by the displacementmethod described by BOhm(1979). Seedling mass was.recorded after seedlings were oven dried and weighed ona top loading balance. SAS Version 8.2 (SAS 2000) was used to conduct the analysis of variance, to test hypothesesrelating acorn mass, acorn size and initial shoot growth to first-year RPMTM seedling morphology, and to determine

"least significant differences (LSD) between treatment means. _

RESULTS AND DISCUSSION

Effect of Acorn Mass, Size and Precocious Shoot Growth on Seedling Characteristics

Precocious shoot growth was not significantly related to first-year root or shoot size or morphology in either Quercuspopulations based on the Latin square design. Analysis of least significant differences showed that, seedlings fromthe light-small acorn treatment were consistently larger than any other acorn mass-size treatment combination (fig.1). Significant differences were found among all eight treatments (i.e., all combinations of acorn mass and size, andprecocious shoot growth) that were analyzed with the lattice square design from both Quercuspopulations, but thesedifferences were notconsistent for one particular treatment with one exception (fig. 2). For example, the heavy-small-precocious treatment from the Q. bicolor population wasconsistently, but not always, significantly larger than the othertreatments from that population.

Results found here are not consistent with most research on the acorns effect on seedling .characteristics.Researchers have found that seed mass is positively correlated or significantly related to earlyseedling growth (i.e.,Eytingen 1917; Korstian1927; McComb t 934; Riceet al. 1993; Bonfil 1998). Rodger (1920) however, found no effectof acorn mass andsize on seedling characteristics, but his sample was too small to make definitive conclusions. Longand Jones (1996) also found no effect of acorn mass and size on seedling characteristics, but suggests that poorcontrol over acorn moisture content (in their study and others) and .genotypic variation on seed size could haveinfluenced their results. Studies that involved the removal of a portion of the acorn prior to sowing, or removal of thecotyledons shortly after germination, found that seedling growth was more effected by poor soil nutrition than by lossof acorn mass (Sonesson 1994; Anderson and Frost 1996). Furthermore, it has been speculated that acorn size may.

237

be more important in attracting wildlife for seed dispersal than for first-year-growth (Stiles 1980; Anderson and Frost1996}.

Conflicting results may also be due to differences in propagation methods. Traditionally seedlings have been grownin seedbeds as bare-rooted nursery stock under less than ideal conditions for rapid growth. Containerized RPMTM

seedlings grown in the greenhouse under optimal growing conditions are under no stress and are absent ofcompetition relativeto seedlingsgrown in the wild or innursery beds. Largerseeds may have advantagesover smallerseeds if both are grown in competition (Wulff 1986; Bonfil 1998), but under low stress and competition-freeenvironments, little appears to be gained from larger seeds.

In addition to the absence,of stress or competition_RPMTMseedlings have an extremely dense, fibrous root systemwith numerous lateral roots providing a greater amount of surface area for the absorption and utilization of.oxygen,water and nutrients than bare-rootedseedlings. Optimal growing conditions provided by the RPMTM systemfacilitatesthe production of a dense, fibrous root system has been shown to remove the effect of acorn mass, size andprecocious shoot growth on oak seedlings after one growing season.

Population Differences

We evaluated the influence of genetics and the RPMTM process on seedling morphology after one growing season bycomparing RPMTM seedlings from two different seed sources. The hybrid Q. x. schuettei acorns were expected toperform betterthan the Q. bicoloracorns from public collections obtained from the state nursery. Seedlingsfrom hybridacornscollected by Forrest Keeling Nursery from precocious mothertrees located in floodplains have beenobservedto flower precociously andabundantly. Tree genetics have been Shownto.regulate mast production (Wolgast 1978).However, we found no significant differences in seedling morphology between populations and only a few significantdifferences among treatments (fig. 1 and fig. 2.). Quercus bicolor seedlings were consistently Jarger than Q. x.schuettei seedlings, but differences were not statistically significant. There is insufficient evidence to conclude thatobserved differences,in seedling morphology between Q. x. schuettei and Q.bicoloracorns after one growingseasonare indicative of future outplanting success and precocity.

Seed collected from superior seed trees have been shown to have increased viability and germinate earlier(Buchschacheret al. 199t), growth responsesthat could prove advantageous in a natural setting (Seiwa 2000).Timingof germinat!on, as well as values of allmeasured variables, varied more in Q. bicolorthan inhalf-sibling Q. x. schuetteiacorns, possibly due to the greater degree of genetic diversity found in the randomly collected Q. bicolor acorns(Mercier et al. 1996).

IMPLICATIONS

Bottomland regeneration with bare-rooted seedlings has typically relied on planting oak species at a tight, uniformspacing, typically 12 by 12feet. Thinning at a later date is typically necessary to allow full canopy expansion. RPMTM

seedlings are larger than bare-rooted seedlings at the time of planting and are expected to reach canopy closuresooner; therefore a wider spacing is used (30 by 30 feet) which may not require future thinning. Furthermore,bottomland reforestation with RPMTM seedlings has been very successful, with little or no mortality and acornproduction in the third or fourth year (Dey et al. 2001). Precocious flowering and fruiting provides an excellentopportunity for natural regeneration as well as forage for acorn consuming wildlife much earlier than traditional oak.plantings.

An alternative to an oak monoculturefor bottomland reforestation is implementing an agroforestry design by plantingmast-producing RPMTM seedlings (i.e., oak and pecan) at a slightly wider spacing and interplanting early successionalspecies such as cottonwood (Twedt and Portwood 1997). The cottonwood could be harvested twice at ten-yearintervals for pulp wood. During the twenty year period of pulp wood production, acorn-producing RPMTM seedlingswould have the potential to naturally regenerate the stand as weil as provide wildlife forage. After the second pulpwood harvest, RPMTM seedlings and other naturally seeded tree seedlings should be large enough to dominate thereforested tract. Interplanting early-successional species with mast-producing species such as oak and pecan canpromote rapid colonization by migrant birds, enhance plant species diversity, promote a more rapid financial returnto landowners,and enhance the.public's perception of reforestation efforts (Twedt and Portwood 1997).

238

ACKNOWLEDGEMENTS

W_thoutthe assistance from all the individuals at Forrest Keeling Nursery,noneOfthis would have been possible, andfor that we are grateful. The technical assistance of the Universityof Missouri Department of Forestry, the Center forAgroforestry and the Missouri Department.of Conservation State Nursery is also gratefully acknowledged, This workwas funded under cooperative agreement C R 826704-01-0 with the US EPA. The resultspresented a_-ethe soleresponsibility of the P.l.'s and may not represent the policies or positions of the EPA.

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241

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