***Compass*--Summer 2001**

**The Southern Research Station**

**Recent Publications Catalogue**

**(http://www.srs.fs.fed.us/pubs/)**

Managing Forests---Maximizing Carbon Storage

Atmospheric CO~2~ (an important "greenhouse" gas) is rising at a
historically rapid pace, mainly due to global conversion of forests to
agriculture and urban landscapes, combined with increasing quantities of
CO~2~ emitted from burning fossil fuels. There is advancing theoretical
and empirical evidence that increasing greenhouse gases may be altering
the world's climate. As such, there has been considerable international
deliberation, both political and scientific, on potential avenues to
reduce net carbon emissions.

While many short-term studies have shown atmospheric carbon dioxide
increases tree growth, an article co-authored by three Southern Research
Station scientists takes a longer view. *Soil Fertility Limits Carbon
Sequestration by Forest Ecosystems in CO~2~-enriched Atmosphere*,
published in the May 24 issue of *Nature*, indicates that along a
gradient of decreasing site fertility, nutrient amendments (nitrogen)
would become increasingly necessary if forested ecosystems are to help
reduce the rate at which atmospheric carbon dioxide concentrations
increase. The study is part of the effort to understand the relationship
between forests, which often are limited to sites with low nutrient
soils, and carbon sequestration, in order to estimate current and future
global carbon budgets. Lead author is Ram Oren, School of the
Environment and Earth Sciences, Duke University. Ten co-authors include
Southern Research Station scientists Kurt Johnsen and Chris Maier of
Research Triangle Park, and Steve McNulty of Raleigh. Johnsen serves as
project leader for the Biological Foundations of Southern Forest
Productivity and Sustainability research unit. Maier performs research
as a biologist in the RTP project. Steve McNulty is an ecologist with
the Southern Global Change Program. Ram Oren's co-principal investigator
is David Ellsworth, School of Natural Resources, University of Michigan,
Ann Arbor, and the Brookhaven National Laboratory in Upton, N.Y. In
addition to Forest Service scientists Johnsen, Maier, and McNulty, other
co-authors include Nathan Phillips, Department of Geography, Boston
University; Karina Schäfer, Heather McCarthy, Brent Ewers, and Gabriel
Katul, Duke; and George Hendrey of Brookhaven, who designed and
engineered the Duke Forest site of the experiment.

The experiments reported in *Nature* showed that without additional
nutrients, initial growth increases of mature loblolly pine trees
leveled off after the first three years of exposure. In addition to
nutrient limitations, growth responses were also sensitive to the
availability of soil moisture. The presence of elevated levels of carbon
dioxide alone, which is occurring due to global industrialization and
land use changes, may not result in a long-term increase in the rate of
tree growth. However, the results also suggest that forest
fertilization, already a practice in Southern pine plantations, might
become even more beneficial in a high carbon dioxide world.

In light of discussions of the findings presented in *Soil Fertility
Limits Carbon Sequestration by Forest Ecosystems in CO~2~-enriched
Atmosphere*, Johnsen, Oren, McNulty, and Maier chose to address the
prevailing misconception that forests will not be important in absorbing
CO~2~ from the atmosphere and thus will not help to mitigate climate
change. This ignores the fact that carbon absorption by the pine trees
from both the present-day atmosphere and from the manufactured
atmosphere representing the future was substantial. The authors did find
that the CO~2~-absorbing capacity of the experimental forests was not
increased much from what it is in the present by the higher CO~2~ that
simulates future conditions. So the unfortunate conclusion drawn by some
is that contrary to expectations of many scientists and policy-makers,
current forests on low fertility soils, represented by this study, will
not take up [more]{.underline} CO~2~ in the future than it does today.
The authors concluded that nutritional and water limitations to growth
must be considered in computer models that predict forest responses to
elevated CO~2~. This is especially important since results from these
models can be the basis of some policy decisions.

We use the Southern United States, the region where the study was done,
as one example of the potential of forests to sequester atmospheric
carbon. Carbon sequestration in southern pine forests continues to
increase with improvements in forest management. The nearly four-fold
increase in pine productivity over the last half-century is the result
of genetic improvement, site preparation, and other management
activities. Larger trees over time are a consequence of greater amounts
of carbon absorbed from the atmosphere. When southern pine forests are
eventually harvested, various forest products such as conventional
lumber, fiberboard, and paper products have "life-spans" during which
time the carbon in them is kept out of the atmosphere. Remaining parts
of harvested trees like taproots can be slow to decay, thereby further
retaining carbon out of the atmosphere. Although in an associated study
soil carbon was not shown to increase strictly due to elevated CO~2~
over a three-year period, other longer-term studies have shown that
productive forests do increase soil carbon, particularly if they are
established on sites that were degraded by past agriculture practices.
Furthermore, in the Southern U.S., converting the over 15 million acres
of marginal agriculture land to pine forests could produce a 20-fold
increase in carbon sequestration on those sites. So planting forests is
not as futile as has been stated based on misinterpretation. The
opposite trend, the conversion of forests to agriculture and urban
landscape, releases large amounts of carbon into the atmosphere.

Thus, higher productivity and more forest acreage in the Southern U.S.
could increase carbon sequestration to account for an additional 5
percent of the CO~2~ produced by the United States annually, and
conservation of forests, both regionally and globally, is imperative for
stemming increasing atmospheric CO~2~. Although not a panacea, this
represents an important and realistic tool for mitigating increasing
atmospheric CO~2~ concentrations.

The results from the studies described in *Soil Fertility Limits Carbon
Sequestration by Forest Ecosystems in CO~2~-enriched Atmosphere*
indicate that, contrary to hopes, future growth of current forests may
not become a stronger sink for, and may not sequester
[more,]{.underline} carbon than now as a direct result of projected
CO~2~ increases. However, this work should not be used to minimize the
importance of forests in the global carbon budget or to refute the
potential value of managed forests to reduce overall CO~2~ net
emissions. Collaborative sources funded this study: the USDA Forest
Service; the U.S. Department of Energy, Office of Health and
Environmental Health and Environmental Research; the National Institute
for Global Environmental Change, Southeast Regional Center at the
University of Alabama; and the National Science Foundation's Multi-user
Instrument Program.

The Summer 2001 issue of *Compass* includes several articles about
forest management and carbon dioxide:

Booker, Fitzgerald L.; Maier, Christopher A. 2001. **Atmospheric carbon
dioxide, irrigation, and fertilization effects on phenolic and nitrogen
concentrations in loblolly pine (*Pinus taeda*) needles.** Tree
Physiology. 21: 609-616. **(1)**

Johnsen, Kurt H.; Wear, D.; Oren, R.; and others. 2001. **Carbon
sequestration and southern pine forests.** Journal of Forestry. 99(4):
14-21. **(4)**

Oren, Ram; Ellsworth, David S.; Johnsen, Kurt H.; and others. 2001.
**Soil fertility limits carbon sequestration by forest ecosystems in a
CO~2~--enriched atmosphere.** Nature. 411: 469-472. **(16)**

Dating Stream Sediments

Government agencies responsible for water quality, as well as anyone
whose drinking water, recreational activities, or economic livelihood
depends on stream health, demonstrate increasing interest in determining
whether stream sediment at a particular location is the result of recent
terrestrial erosion or reworking of sediment already in the drainage
system. Jonathan D. Phillips, University of Kentucky, and Daniel A.
Marion, Southern Research Station, have developed new and more
affordable field and laboratory techniques to address this question. In
*Residence Times of Alluvium in an East Texas Stream as Indicated by
Sediment Color*, Phillips, a University of Kentucky geographer, and
Marion, a research hydrologist in Oxford, MS, use sediment residence
times to discriminate between "new" sediment caused by recent erosion
outside a stream and "old" sediment that was eroded in the past and
stored within a stream.

The Environmental Protection Agency is charged with developing watershed
goals for areas identified as being in an impaired state. The Total
Maximum Daily Load (TMDL) sets the allowable amount of sediment moving
through a stream. Marion says, "If monitoring reveals a TMDL has been
exceeded, the next question becomes, 'Whose sediment is it?'" One path
to finding the answer could be determining the sediment's age. Phillips
and Marion show that soil color can indicate the length of time sediment
has been stored at a sampled site. Hypothetically, if these methods
revealed soil characteristics specific to new sediment, then the focus
of regulatory agencies could shift to determining the cause of erosion.

The authors caution that their methods are only applicable where soils
contain a large amount of iron oxides (a characteristic of many soils in
the South). They also state that soil color indicators are most useful
when combined with other methods. The depth of sediment covering the
root collar of trees and root growth patterns can reveal physical
history before and after flooding. Buried soil horizons, the presence of
invasive tree species, and the age of buried trees can provide
additional evidence to more precisely date sediment or demonstrate
changes in sedimentation rates.

Dan Marion, a scientist in the Managing Upland Forest Ecosystems in the
Midsouth research unit, headed by Jim Guldin, began working with
Jonathan Phillips when the geographer was with Texas A&M University.
Phillips' ideas about geochemical dating and soil characteristics formed
the basis for their research on stream sedimentation in Loco Bayou, a
tributary of the Angelina River. Using the research methods described in
*Residence Times of Alluvium in an East Texas Stream as Indicated by
Sediment Color* could cost a couple of thousand dollars. In contrast,
using radionuclide methods would cost several times as much. Phillips
and Marion plan to continue their sediment dating research. Their next
study will focus on more quantitative and rigorous analysis of iron
reduction in soils so as to better refine sediment residence times.

To receive a copy of *Residence Times of Alluvium in an East Texas
Stream as Indicated by Sediment Color*, circle publication **8** on the
request card.

Station News

**Conferences and Workshops**

The **8th Workshop on Seedling Physiology and Growth Problems in Oak
Plantings** takes place September 9-12 in Hiawassee, GA. The USDA Forest
Service, Southern Research Station, Institute of Tree Root Biology, and
the Southern Region, join the Georgia Forestry Commission to sponsor
this workshop. The three-day event covers regeneration involving
silvicultural manipulation, physiological attributes, tree improvement,
and insects and disease problems. Private and industrial landowners,
nursery owners, land managers, and scientists will find topics to
interest them. One session will feature a demonstration on how to
establish a 2 acre oak stand. The meeting will include equal sessions of
oral presentations, discussions, and field trips. The
Hiawassee-Blairsville area of North Georgia straddles the Appalachian
Trail. The forests in this region are experiencing transition, with many
oak species declining as faster growing, more shade-tolerant species
begin to dominate the higher quality sites. Workshop planners say oak
biological attributes may be the essential element needed to
successfully regenerate the many important species of oak.

For more information about the 8th Workshop on Seedling Physiology and
Growth Problems in Oak Plantings, please contact Paul P. Kormanik,
Institute of Tree Root Biology, 706-559-4288; Susana Sung, 706-559-4289,
<ssung@fs.fed.us>; or William Otrosina, 706-559-4295,
<wotrosina@fs.fed.us>.

That place where urban lands meet and interact with rural lands defines
the wildland-urban interface (WUI). To understand the meaning of the
term, consider attending the **Wildland-Urban Interface: Sustaining
Forests in a Changing Landscape** conference in Gainesville, FL,
November 5-8. A field trip on the first day will introduce participants
to WUI issues in Florida. Forestry and natural resource managers and
scientists, arborists and horticulturists, industry and consulting
foresters, and Federal, State, regional, county, and city planners and
policymakers can benefit from attending the conference. Sponsors include
the USDA Forest Service, Southern Research Station and Southern Region,
the University of Florida, and the Southern Group of State Foresters.
For more information, contact Mary L. Duryea at 352-846-0896 or
<mlduryea@ufl.edu>, or Susan W. Vince at 352-846-0886 or
<svince@ufl.edu>. For information on the Web, visit
http://www.conference.ifas.ufl.edu/urban.

Southern forests provide immeasurable benefits for our country. This
diverse region supports rich ecological, economic, and cultural systems.
Plan now to attend the **Southern Forest Science Conference** in Atlanta
on November 26-28. Sponsored by southern forest science and management
communities, this conference will celebrate past accomplishments and
create a vision for the future of southern forestry research and
management. Scientists, managers, owners, and users of southern forests
share a common desire to sustain and improve these forests and the
benefits they provide. The USDA Forest Service, Southern Research
Station and Southern Region co-sponsor the Southern Forest Science
Conference. For more information, contact Hermann Gucinski or Nancy
Walters, Southern Research Station, 828-257-4302, or visit
[http://www.southernforestscience.net](http://www.southernforestscience.net/).

**Accomplishments and Awards**

**Cassandra Johnson** recently graduated from the University of Georgia
with a Ph.D. in sociology. Cassandra, a social scientist in Ken
Cordell's unit in Athens, GA, focuses on environmental sociology and
natural resources. Johnson researches attitudes about outdoor recreation
and leisure, environmental justice, and ethnicity. Congratulations, Dr.
Johnson!

Southern Station Director **Pete Roussopoulos** received the 2000
Presidential Rank Award of Meritorious Executive. Winners of this
prestigious award have demonstrated ability to lead a Government Agency
that delivers great service, fosters partnerships and community
solutions to achieve results, and continuously pushes itself to get the
job done more effectively and efficiently. Only one of two Senior
Executives in the Forest Service to receive this award, Pete was
recognized for outstanding service in natural resources and the
environment. Pete became Director of the Southeastern Forest Experiment
Station in 1992. In 1995 he became Director for the combined Southern
Research Station, responsible for Forest Service Research and
Development throughout the 13 Southern States. We are proud of you,
Pete, and the work you encourage us to accomplish.

The Southern Appalachian Mountains and the Biosphere, known as SAMAB,
honored **Nancy Herbert**, Southern Research Station Assistant
Director---Mountains with the Hinote Award. Nancy earned this honor for
her dedication during her two terms as vice president of the SAMAB
executive committee and for stepping up to fill the vacated
chairperson's position.

The U.S. Department of Agriculture recognized two Southern Research
Station scientists with the USDA Honor Award. **James H. Miller** is a
research ecologist and team leader in Charlie McMahon's silviculture
project, located on the campus of Auburn University in Alabama. The USDA
honors Jim's leadership in research and outreach to further plant
conservation and nonnative plant management for sustaining productivity
and biodiversity in the forests of the Southeastern United States.

**Hermann Gucinski**, Assistant Director for Research---Global Change,
received the USDA Honor Award as a member of the intra-agency Climate
Change Negotiations Analytic Support Team. The team made significant
contributions to improving the Kyoto Protocol through the consideration
of forest, crop, and grazing land management. In addition to overseeing
the Southern Global Change research work unit in Raleigh, NC, Hermann
oversees the Forested Wetlands and Bottomland Hardwoods research work
units in South Carolina and Mississippi and other related Southern
Research Station work.

The Chief of the Forest Service Honor Award for Distinguished and
Superior Science was bestowed on **Ken Cordell**, project leader in
Athens, GA, located on the University of Georgia campus. Ken has been a
champion for understanding visitor preferences for natural resources
experiences on public lands for four decades. Cordell received the award
to honor his national and international science leadership in developing
methods for conducting broad-scale assessments of long-term trends in
outdoor recreation, wilderness, and American demographics. Government
agencies and private organizations use these assessments extensively in
planning, policy, research, and education.

**Wayne T. Swank**, research ecologist emeritus at the Coweeta
Hydrological Laboratory; **Robert C. Thatcher**, former Southeastern
Forest Experiment Station assistant director for research in Georgia and
Florida; and **Charles C. Van Sickle**, former assistant director for
research in the Carolinas and Virginia, Southeastern Forest Experiment
Station and Southern Station, received the honorable title of Fellow of
the Society of American Foresters (SAF). This organization awards the
honor of Fellow based on an individual's strong continuing commitment
through direct SAF volunteer activities and exemplary action, sustained
leadership, and advancement of the forestry profession at the local,
regional, national, or international level. An applicant for Fellow must
be nominated by 30 peers and voted on by the SAF membership.

**Familiar Faces in New Places**

Congratulations to **John Kelly**, promoted to assistant director for
Inventory and Monitoring. John oversees the research and field
components of Forest Health Monitoring and Forest Inventory and Analysis
(FIA), and the research units for forest products and forest operations.
John began his Forest Service career in 1985 as a research forester in
the FIA project in Starkville, MS. John initiated the process of
changing from flat data files for each State to a regional relational
database. John became project leader in 1994, and moved to Asheville in
1996 as Inventory and Monitoring program manager for the Southern
Research Station. Under John's leadership, the Southern Station has
established an east-wide database. We are in the processing of migrating
to the national FIA database.

**Rob Doudrick** moves to the Forest Service's Washington Office to
become staff assistant to the budget coordinator for Research and
Development. Rob has served as the Southern Research Station's Assistant
Director for Planning and Applications since 1998. He has led the
Station's efforts to increase outreach efforts to underserved customers.
Doudrick began his Forest Service career in Gulfport, MS, as a
post-doctoral plant pathology student. The research unit moved to
Saucier---which borders on Success---where Rob became project leader in
1989. During the last year, Rob has been a Legislative Fellow with
Congressman Charles Taylor's office. We will miss you, Rob, but we will
definitely work to stay on your radar screen! Congratulations to you and
your family as you travel further.

**Pauline Spaine** joins Congressman Taylor's office as legislative
assistant for environmental issues. Paula is a plant pathologist in
Kerry Britton's Insects and Diseases of Southern Forests unit in Athens,
GA.

**Bruce Jewell** has joined the Southern Research Station as Assistant
Director for Research. Bruce oversees the research work units involved
with southern pines. Bruce was Deputy Director of State and Private
Forestry at the Southern Region, so we know he will enhance our strong
connection with the Southern Region and the customers we serve together.
Welcome, Bruce!

**Southern Pines Research**

Booker, Fitzgerald L.; Maier, Christopher A. 2001. **Atmospheric carbon
dioxide, irrigation, and fertilization effects on phenolic and nitrogen
concentrations in loblolly pine (*Pinus taeda*) needles.** Tree
Physiology. 21: 609-616.

Concentrations of total soluble phenolics, catechin, proanthocyanidins
(PA), lignin and nitrogen (N) were measured in loblolly pine *(Pinus
taeda* L.) needles exposed to either ambient CO~2~ concentration
(\[CO~2~\]), ambient plus 175 or ambient plus 350 μmol CO~2~ mol^‑1^ in
branch chambers for 2 years. The CO~2~ treatments were superimposed on a
2 x 2 factorial combination of irrigation and fertilization treatments.
In addition, we compared the effects of branch chambers and open‑top
chambers on needle chemistry. Proanthocyanidin and N concentrations were
measured in needles from branch chambers and from trees in open‑top
chambers exposed concurrently for two years to either ambient \[CO~2~\]
or ambient plus 200 μmol CO~2~ mol^‑1^ in combination with a
fertilization treatment. In the branch chambers, concentrations of total
soluble phenolics in needles generally increased with needle age.
Concentrations of total soluble phenolics, catechin, and PA in needle
extracts increased about 11 percent in response to the elevated
\[CO~2~\] treatments. There were no significant treatment effects on
foliar lignin concentrations. Nitrogen concentrations were about 10
percent lower in needles from the elevated \[CO~2~\] treatments than in
needles from the ambient \[CO~2~\] treatments. Soluble phenolic and PA
concentrations were higher in the control and irrigated soil treatments
in about half of the comparisons; otherwise, differences were not
statistically significant. Needle N concentrations increased 23 percent
in response to fertilization. Treatment effects on PA and N
concentrations were similar between branch and open‑top chambers,
although in this part of the study N concentrations were not
significantly affected by the CO~2~ treatments in either the branch or
open‑top chambers. We conclude that elevated \[CO~2~\] and low N
availability affected foliar chemical composition, which could, in turn,
affect plant--pathogen interactions, decomposition rates, and mineral
nutrient cycling. (1)

Boyer, William D. 2001. **A generational change in site index for
naturally established longleaf pine on a south Alabama Coastal Plain
site.** Southern Journal of Applied Forestry. 25(2): 88-92.

Research on longleaf pine (*Pinus palustris* Mill.) has been carried out
for over 50 yr on a Coastal Plain site in south Alabama. Studies have
included the original second‑growth stands and also naturally
established third‑growth stands. Site index data revealed that estimated
site index values for third growth generally exceeded those for second
growth. Age 50 site index in 16 study compartments with second growth
near index age averaged 66 ft. Estimated site index for third‑growth
stands recorded in 17 different compartments averaged 81 ft. Nine of the
16 compartments with second‑growth stands now include third growth about
40 yr in age. This provided an opportunity to make a direct comparison
of generational site index differences within the same compartments.
Site index for second growth averaged 65 ft (range 61 to 70 ft), while
third growth averaged 83 ft (range 77 to 87 ft). Reasons for this large
increase in apparent site quality are unknown, but since soils are the
same, some climate changes may be suspect. **(2)**

Glitzenstein, Jeff S.; Streng, Donna R.; Wade, Dale D.; Brubaker, John.
2001. **Starting new populations of longleaf pine ground-layer plants in
the outer Coastal Plain of South Carolina, USA.** Natural Areas Journal.
21: 89-110.

Southeastern United States habitats dominated by longleaf pine *(Pinus
palustris* Miller) and associated plant species have declined
dangerously. Conservation of rare and common plants of longleaf pine
habitats may be aided by starting new populations in the field. We
review methods for initiating plant populations and integrate
information from our studies of rare and common longleaf pine
ground‑layer plants of the outer South Carolina Coastal Plain. In our
experience it is possible to start new populations of most longleaf pine
ground‑layer plants, including rare species, if (1) seeds are collected
from frequently burned sites with reasonably large populations of
desired species; (2) appropriate media are used for seedling
propagation; (3) outplanting of nursery grown seedlings or direct
seeding is done during periods of sufficient soil moisture; and (4)
introduction sites properly match habitat requirements (inferred from
indicator plants) of desired species, and the sites can be managed with
frequent prescribed fire. **(3)**

Johnsen, Kurt H.; Wear, D.; Oren, R.; and others. 2001. **Carbon
sequestration and southern pine forests.** Journal of Forestry. 99(4):
14-21.

In managed forests, the amount of carbon further sequestered will be
determined by (1) the increased amount of carbon in standing biomass
(resulting from land-use changes and increased productivity); (2) the
amount of recalcitrant carbon remaining below ground at the end of
rotations; and (3) the amount of carbon sequestered in products created
from harvested wood. Because of the region's high productivity and
industrial infrastructure, carbon sequestration via southern pine
forests could be increased, and this may benefit the Nation in terms of
global policy commitments. **(4)**

Klepzig, K.D.; Moser, J.C.; Lombardero, F.J.; and others. 2001.
**Symbiosis and competition: complex interactions among beetles, fungi,
and mites.** Symbiosis. 30: 83-96.

Symbioses among bark beetles and their fungal and mite associates
involve complex, multi‑level interactions. *Dendroctonus frontalis*
attacks and kills southern pines, introducing fungi into the tree.
*Ophiostoma minus* may initially aid beetles in killing trees, but later
this \"bluestain\" fungus becomes an antagonist, competing with larvae
for host phloem. Two additional fungi, *Entomocorticium sp. A* and
*Ceratocystiopsis ranaculosus* are carried within a specialized
mycangium and inoculated into phloem where they are fed upon by beetle
larvae. The beetle also vectors several species of phoretic mites, which
transport spores of O. minus, and *C.* *ranaculosus* and can complete
their life cycle upon these two fungi. A similar interaction occurs
between *Ips avulsus* and its fungal *(Entomocorticium* spp.) and mite
*(Elattoma bennetti)* symbionts. Larval beetles feed on fungus, as do
the mites. Female mites feed on fungus growing within beetle galleries,
swelling to many times their normal size. Larval mites develop and mate
within the females who burst open, giving birth to reproductively mature
females. These relationships may be best understood by considering the
manner in which symbioses vary with time and resources, and the degree
to which other species may affect interactions among symbionts. **(5)**

Saenz, Daniel; Conner, Richard N.; Collins, Christopher S.; Rudolph, D.
Craig. 2001. **Initial and long-term use of inserts by red-cockaded
woodpeckers***.* Wildlife Society Bulletin. 29(1): 165-170.

Artificial cavities have become a standard management technique for
red‑cockaded woodpeckers *(Picoides borealis).* Seventy cavity inserts
were installed in our study sites on the Angelina National Forest in
eastern Texas from 1990 to 1995. Eighty‑two percent of the inserts were
used for at least one year. It is still too early to make a direct
comparison, but it is likely that inserts will remain usable as long as
natural cavities do. Inserts installed in 1990 and 1991 were 20.5 cm in
height, whereas inserts installed from 1992 to 1995 were 25.5 cm in
height. Larger inserts *(*25.5 cm) appear to remain usable for a longer
time than smaller inserts *(*20.5 cm). Newer unused inserts are more
likely to become active for the first time than older unused inserts.
Similar to unused inserts, active cavities (naturally excavated and
inserts) that have become inactive are less likely to be reactivated the
longer they are inactive. Newness and recency of cavity use and
red‑cockaded woodpecker activity appear to be important factors in the
attractiveness of inserts and naturally excavated cavities. **(6)**

Welch, Nicole Turrill; Waldrop, Thomas A. 2001. **Restoring table
mountain pine (*Pinus pungens* Lamb.) communities with prescribed fire:
an overview of current research.** Castanea. 66(1-2): 42-49.

Table mountain pine (*Pinus pungens* Lamb.) communities of the Southern
Appalachian Mountains have been maintained historically by lightning‑
and human‑caused fires. Characteristic stands have a table mountain pine
overstory, a chestnut oak (*Quercus prinus* L.), scarlet oak (*Q.
coccinea* Muenchh.), and blackgum (*Nyssa sylvatica* Marshall)
understory, and a mountain laurel (*Kalmia latifolia* L.) shrub layer.
Following more than 60 years of fire suppression, most stands have
increased densities of oaks and mountain laurel, as well as
fire‑intolerant species such as red maple (*Acer rubrum* L.) and white
pine (*P. strobus* L.). Previous research suggests that restoration of
these communities can only be accomplished with high intensity fires
that open the forest canopy and expose mineral soil. Opportunities to
conduct such burns, however, are limited under current prescribed
burning guidelines. Two recent studies examined community response to
prescribed burning. Fires of low and medium‑low intensity gave rise to
abundant regeneration, but may not have killed enough of the overstory
to prevent shading. High‑intensity fires killed almost all overstory
trees but may have destroyed some of the seed. Fires of medium‑high
intensity may have been most successful; they killed overstory trees and
allowed abundant regeneration. Large numbers of these seedlings survived
the first growing season as their roots penetrated duff to reach mineral
soil. Hardwood rootstocks resprouted after all fire intensities and may
out‑compete pine seedlings for available resources. Fires of lower
intensity than previously recommended may best provide conditions for
table mountain pine regeneration, but additional research is needed.
Prescriptions calling for lower intensity fires may widen the burning
window defined by current guidelines. **(7)**

**Wetlands, Bottomland Hardwoods, and Streams Research**

Phillips, Jonathan D.; Marion, Daniel A. 2001. **Residence times of
alluvium in an east Texas stream as indicated by sediment color.**
Catena. 45: 49-71.

The relationships between sediment production, storage, and transport in
fluvial systems are complex and variable. Key issues in addressing these
relationships are the residence times of sediment delivered to the
channel, and the proportion derived from recent upland erosion as
opposed to remobilized alluvium. The systematic changes in iron
geochemistry often experienced by sediments deposited in an anaerobic
environment, such as a stream channel or waterlogged floodplain, are
used here as an indicator of residence time over contemporary time
scales. In areas such as east Texas, where upland soils are high in iron
oxide content, these changes are reflected in soil color. Alluvium with
red, yellow, or brown colors indicating ferric oxidized iron and
sufficient organic matter for reduction to occur indicates a short (\< 1
year) residence time. Redox features along root channels may indicate
the residence time of oxidized material without organic matter. Alluvium
with gley colors (Munsell chroma \< 3) indicates a longer residence time
(\> 1 year). Sediments with the longest residence times in alluvial
environments (\>\> 1 year) will not oxidize on exposure to the
atmosphere due to the loss of iron, while those with ferrous iron
remaining will experience oxidation and color change on exposure. In
Loco Bayou, Texas, these indicators of residence time are shown to be
generally consistent with other field evidence of erosion and
sedimentation. Further, the color indicators correctly indicate the
residence time in several cases where the latter is known from field
observations. **(8)**

Stanturf, John A.; Schoenholtz, Stephen H.; Schweitzer, Callie Jo;
Shepard, James P. 2001. **Achieving restoration success: myths in
bottomland hardwood forests.** Restoration Ecology. 9(2): 189-200.

Restoration of bottomland hardwood forests is the subject of
considerable interest in the Southern United States, but restoration
success is elusive. Techniques for establishing bottomland tree species
are well developed, yet problems have occurred in operational programs.
Current plans for restoration on public and private land suggest that as
many as 200,000 ha could be restored in the Lower Mississippi Alluvial
Valley alone. The ideal of ecological restoration is to reestablish a
completely functioning ecosystem. Although some argue that afforestation
is incomplete restoration, it is a necessary and costly first step but
not an easy task. The 1992 Wetlands Reserve Program in Mississippi,
which failed on 90 percent of the area, illustrates the difficulty of
broadly applying our knowledge of afforestation. In our view, the focus
for ecological restoration should be to restore functions, rather than
specifying some ambiguous natural state based on reference stands or
pre‑settlement forest conditions. We view restoration as one element in
a continuum model of sustainable forest management, allowing us to
prescribe restoration goals that incorporate landowner objectives.
Enforcing the discipline of explicit objectives, with restoration
expectations described in terms of predicted values of functions, causal
mechanisms, and temporal response trajectories, will hasten the
development of meaningful criteria for restoration success. We present
our observations about current efforts to restore bottomland hardwoods
as nine myths, or statements of dubious origin, and at best partial
truth. **(9)**

**Southern Appalachians Research**

Swank, W.T.; Vose, J.M.; Elliott, K.J. 2001. **Long-term hydrologic and
water quality responses following commercial clearcutting of mixed
hardwoods on a Southern Appalachian catchment.** Forest Ecology and
Management. 143: 163-178.

Long‑term changes (∼20 years) in water yield, the storm hydrograph,
stream inorganic chemistry, and sediment yield were analyzed for a 59 ha
mixed hardwood covered catchment (Watershed 7) in the Southern
Appalachian Mountains (USA) following clearcutting and cable logging.
The first year after cutting, streamflow increased 26 cm or 28 percent
above the flow expected if the forest had not been cut. In subsequent
years, discharge increases declined at a rate of 5--7 cm per year until
the fifth year, when changes in flow returned to baseline values. Later
in forest succession, between ages 15 and 18 years, both significant
increases and decreases in annual water yield were observed; these
discharge dynamics are discussed in relation to vegetation regrowth
dynamics. Flow responses predicted from an empirical regional scale
model were within 17 percent of experimental values during the first 4
years of regrowth. Intra‑annual analysis showed that proportionally
larger increases (48 percent) in flow occurred in the low flow months of
August--October. Storm hydrograph analysis showed that, on an average,
initial flow rate and peakflow rates increased 14--15 percent, and
stormflow volume increased 10 percent.

Analyses of stream solute concentrations and catchment nutrient fluxes
showed small increases in nutrient losses following clearcutting and
logging. Responses were largest the third year after treatment, with
annual values of 1.3, 2.4, 2.7, 3.2, 1.4, 0.39, and 2.1 kg ha^‑1^ for
NO~3‑~N, K, Na, Ca, Mg, S, and Cl, respectively. Explanations for the
retention of nutrients and high ecosystem resistance and resilience are
discussed in relation to internal biogeochemical cycles based on
long‑term process level studies on the catchment. A second, sustained
pulse of NO~3~^--^ to the stream (exceeding post‑harvest values)
observed later in succession is also discussed in the context of
ecosystem processes. Large increases in sediment yield were measured
immediately after road construction due to two major storm events.
Subsequently, during logging, sediment yield from roads was greatly
reduced and insignificant when logging activities were completed. In
contrast, cumulative increases in sediment yield were observed
downstream over the next 15 years, which illustrate the lag between
pulsed sediment inputs to a stream and the routing of sediments through
a stream system. The relevance of sedimentation to stream sustainability
is discussed in the context of long‑term responses in the benthic
invertebrate community structure and productivity measured on Watershed
7. **(10)**

**Interior Highlands Research**

Cain, Michael D.; Shelton, Michael G. 2001. **Secondary forest
succession following reproduction cutting on the Upper Coastal Plain of
southeastern Arkansas, USA.** Forest Ecology and Management. 146:
223-238.

To contribute to an understanding of forest management on secondary
forest succession, we conducted vegetation surveys in a chronosequence
of pine stands ranging in age from 1 to 59 years. Adjacent areas were
compared at 1, 7, 12, and 17 years following two reproduction cutting
methods (clearcuts or pine seed‑tree cuts); a 59‑year‑old pine stand
that was periodically thinned was also included to represent conditions
before reproduction cutting. Because average or better natural loblolly
and shortleaf pine *(Pinus taeda* L. and *P. echinata* Mill.) seed crops
coincided with the planned site disturbances, pines dominated the
seedling‑size classes at 1 and *7* years after reproduction cutting, the
sapling‑size classes at 7, 12, and 17 years after reproduction cutting,
and the small‑ and large‑tree size classes at 12, 17, and 59 years after
reproduction cutting. For seedling size classes, three measures of woody
plant diversity (Shannon\'s *(H\'),* Simpson\'s *(D),* and evenness
*(e)* indices) tended to increase from 1 to 12 years after reproduction
cutting. In the sapling‑size classes, *H\'* and *D* diversity indices
were highest at 17 years and lowest at 59 years after reproduction
cutting. For small‑tree size classes, *H\',* and *D* were highest at 7
years and lowest at 12 years after reproduction cutting. Across all but
the large‑tree size classes, woody species richness peaked 7 years after
reproduction cutting. Naturally regenerated pines achieved complete
crown closure by 17 years after reproduction cutting; consequently, the
presence of shade‑tolerant woody plants increased in the understory, and
shade‑intolerant herbaceous plants disappeared from the forest floor.
**(11)**

**Large Scale Assessment and Modeling Research**

Bragg, Don C. 2001. **Potential relative increment (PRI): a new method
to empirically derive optimal tree diameter growth.** Ecological
Modelling. 137: 77-92.

Potential relative increment (PRI) is a new method to derive optimal
diameter growth equations using inventory information from a large
public database. Optimal growth equations for 24 species were developed
using plot and tree records from several states (Michigan, Minnesota,
and Wisconsin) of the North Central US. Most species were represented by
thousands of individuals measured across an extensive geographic region
that presumably covered a large range of possible environmental
conditions. Thus, it was assumed that the individuals growing at the
highest rate for each diameter class represented a reasonable estimate
of size‑specific optimal growth. Comparison of PRI equations among
several hardwood and conifer species of differing shade tolerance
indicated that unique patterns of optimal diameter growth result. The
PRI methodology is similar to other optimal growth models in both shape
and trends of predicted growth, but is easier to calculate and offers
more flexibility than many other designs. **(12)**

Greenberg, Cathryn H. 2001. **Spatio-temporal dynamics of pond use and
recruitment in Florida gopher frogs (*Rana capito aesopus*).** Journal
of Herpetology. 35(1): 74-85.

This study examines spatio‑temporal dynamics of Florida gopher frog
*(Rang capito aesopus)* breeding and juvenile recruitment. Ponds were
situated within a hardwood‑invaded or a savanna‑like longleaf
pine‑wiregrass upland matrix. Movement (*N* = 1444) was monitored using
intermittent drift fences with pitfall and funnel traps at eight
isolated, ephemeral ponds February 1994 to January 1999. Adult pond use
was low but relatively constant among years and did not differ between
habitat matrices. Juvenile recruitment was significantly higher in the
savanna‑like upland matrix. The number of adults using ponds was
positively correlated with the number of next‑year\'s recruits in only
one year. Recruitment rates were relatively low (maximum 175
captured/pond/yr), but juveniles were produced from most ponds in three
of five years. Recruitment was negligible in 1994 because of ponds
drying and in 1997 for unknown reasons. Juvenile body size differed
significantly among years and ponds. Body size was negatively correlated
with the number of juveniles exiting ponds in only one year, suggesting
that intraspecific competition is only one of many factors affecting
juvenile body size. Most emigration by metamorphic juveniles occurred
May through August and was unrelated to rainfall. Dates of first
emergence and length of emigration periods varied. A high proportion of
juveniles with tailbuds and similar tailbud lengths in most months
suggest that metamorphosis occurred throughout the emigration period.
High variability in juvenile recruitment success and significant
differences in body size among years and ponds suggests that each is
influenced by factors at both a landscape (e.g., rainfall and pond
hydrology) and within‑pond scale (e.g., competition and predation).
**(13)**

Kilgo, John C. 2000. **Hope is the thing with feathers \[book
review\].** Wilson Bulletin. 112(4): 570-571.

*Hope Is the Thing with Feathers*, written by Christopher Cokinos,
presents accounts of the lives and deaths of six extinct species (or
races) of North American birds: Carolina parakeet, ivory-billed
woodpecker, heath hen, passenger pigeon, Labrador duck, and the great
auk. The message of Cokinos' book is that we must do more than hope; we
must act to prevent the extinction of the species we still have. An
important step in this process is remembering the species and learning
from the mistakes that led to their extinction. **(14)**

Ewers, B.E.; Oren, R.; Johnsen, K.H.; Landsberg, J.J. 2001. **Estimating
maximum mean canopy stomatal conductance for use in models**. Canadian
Journal of Forest Research. 31: 198-207.

Fertilized (F) and irrigated and fertilized (IF) stands of *Pinus*
*taeda* L. produced twice the leaf area index of irrigated (I) and
control (C) stands. Based on sap flux‑scaled mean stomatal conductance
(*G*~S~), we found that stomatal

conductance in F was half that in other treatments. During the growing
season, *G*~S~ was related to vapor pressure deficit

\(D\) and soil moisture. During the cooler season, soil moisture was
high and light accompanied *D* in controlling *GS*. Under all conditions
and treatments, the rate of decrease in *G*~S~ with *D* was proportional
to *G*~S~ at low *D (=* 1 kPa). We

evaluated whether *G*~S~ can be used as an input to growth models and
used a simple growth model (3‑PG), which also

predicts stand transpiration *(E*~C~*),* to compare with direct *E*~C~
measurements in the four stands. Model predictions of

monthly *E*~C~ based on Penman--Montieth equation parameterized with
maximum *G*~S~ (*G*~Smax~) estimated under highest \"native\" soil
moisture (0.07 m^3^.m*^3^)* produced long‑term values within 10 percent
of measured *E*~C~. When the model was parameterized with *G*~Smax~
estimated under experimentally raised soil moisture, or with
porometrically measured conduc­tance, *E*~C~ values were consistently
overpredicted from 12 to 33 percent. Thus, sap‑flux scaled mean canopy
stomatal conduc­tance obtained under non-limiting light conditions, low
*D,* and highest native soil moisture, is the most appropriate parameter
value for certain single-leaf type of models. **(15)**

Oren, Ram; Ellsworth, David S.; Johnsen, Kurt H.; and others. 2001.
**Soil fertility limits carbon sequestration by forest ecosystems in a
CO~2~--enriched atmosphere.** Nature. 411: 469-472.

Northern mid-latitude forests are a large terrestrial carbon sink.
Ignoring nutrient limitations, large increases in carbon sequestration
from carbon dioxide (CO~2~) fertilization are expected in these forests.
Yet, forests are usually relegated to sites of moderate to poor
fertility, where tree growth is often limited by nutrient supply, in
particular nitrogen. Here we present evidence that estimates of
increases in carbon sequestration of forests, which is expected to
partially compensate for increasing CO~2~ in the atmosphere are unduly
optimistic. In two forest experiments on maturing pines exposed to
elevated atmospheric CO~2~, the CO~2~-induced biomass carbon increment
without added nutrients was undetectable at a nutritionally poor site,
and the stimulation at a nutritionally moderate site was transient,
stabilizing at a marginal gain after three years. However, a large
synergistic gain from higher CO~2~ and nutrients was detected with
nutrients added. This gain was even larger at the poor site (threefold
higher than the expected additive effect) than at the moderate site
(twofold higher). Thus, fertility can restrain the response of wood
carbon sequestration to increased atmospheric CO~2~ sequestration to
increased atmospheric CO~2~. Assessment of future carbon sequestration
should consider the limitations imposed by soil fertility, as well as
interactions with nitrogen deposition. **(16)**

Rauscher, H. Michael; Spearman, John E., Jr.; Fout, C. Preston; and
others. 2001. **Talking high-tech turkey: USDA uses new software to
analyze habitat management scenarios.** Tree Farmer. 20(3): 6-9.

Researchers at the USDA Forest Service, Northeastern and Southern
Research Stations, with many collaborators, have been developing a
computer software product called the NED Decision Support System. This
program is designed to help forestry consultants and their private
landowner clients develop goals, assess current and potential
conditions, provide ways to study and select from different scenarios,
and produce management plans for their forest properties. This NED
process has recently been applied to Deer Hill Tree Farm in Gourdin, SC.
The authors discuss the results of field testing NED at a 1000 acre
family-operated farm. **(17)**

Wilson, A. Dan. 2001. **Oak wilt: a potential threat to southern and
western oak forests.** Journal of Forestry. 99(5): 4-11.

Oak wilt is recognized as one of the most destructive diseases to
afflict oak species in the United States. The distribution and
development of oak wilt in our eastern and midwestern oak forests has
been closely linked to changes in forest stand composition, forest
management practices, and pathogen dissemination facilitated by human
and vector activity. The potential for oak wilt to spread into southern
and western States and its possible impacts are discussed. The Texas
experience with an oak wilt epidemic provides useful perspectives and
suppression alternatives for other States not yet touched by this
malady. **(18)**

**Inventory and Monitoring Research**

Dean, Thomas J.; Baldwin, V. Clark, Jr. 1996. **Crown management and
stand density.** In: Carter, Mason C., ed. Growing trees in a greener
world: industrial forestry in the 21st century; 35th LSU forestry
symposium; 1996 January 10-11; Baton Rouge, LA. Baton Rouge, LA:
Louisiana State University Agricultural Center: 148-159a-e \[159ii
revised\].

Stand density management allows a forester to utilize mortality and
promote individual tree vigor. However, even after four decades of
spacing studies, planning for stand-density management remains a
difficult problem. Forest management approaches the problem with
sophisticated analysis, but the heart of the analysis depends on
statistical growth models fit to data from empirical field trials.
Statistical growth-and-yield simulators interface poorly at times with
modern forest management analyses. Even though no better predictor of
the next rotation exists than the performance of the previous rotation,
history data does not exist for every stand, and the combinations of
species, density management, soils, and topography create a matrix too
large to test with spacing studies. Furthermore, changes in cultural
treatments, product specifications, and the physical environment
diminish the predictive value of field trials. Theories are emerging
from recent work to support density-management planning. These theories
focus on the dynamics of crown dimensions in relationship to stand
development and average tree spacing and may aid in developing sound
density-management decisions and managing for desired stand qualities.
In addition, they may aid in overcoming some of the deleterious effects
of climate change, air quality, and site degradation. Mechanistic
linkages between the crown and the stem suggest new uses for traditional
treatments that may stimulate productivity and improve value. **(19)**

Vissage, John S. 2000. **Forest statistics for Southwest-North Alabama,
1999.** Resour. Bull. SRS-56. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 50 p.

This report summarizes a 1999 inventory of the forest resources of a
seven-county area of Alabama. Major findings are highlighted in text and
graphs; detailed data are presented in 49 tables. **(20)**

Vissage, John S. 2000. **Forest statistics for Southwest-South Alabama,
1999.** Resour. Bull. SRS-55. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 50 p.

This report summarizes a 1999 inventory of the forest resources of a
five-county area of Alabama. Major findings are highlighted in text and
graphs; detailed data are presented in 49 tables. **(21)**

**Foundation Programs Research**

Connor, Kristina F.; Bonner, Franklin T. 2001. **The effects of
desiccation on seeds of *Acer saccharinum* and *Aesculus pavia*:
recalcitrance in temperate tree seeds.** Trees. 15: 131-136.

This study was undertaken to determine how the results from lipid,
moisture, and differential scanning calorimetry analyses conducted on
silver maple (Aceraceae: *Acer saccharinum* L.) and red buckeye
(Hippocastanaceae: *Aesculus pavia* L.) compared with those obtained
from previous studies on white and water oaks (Fagaceae: *Quercus alba*
and *Q. nigra),* and the tropical zone species American muskwood
(Meliaceae: *Guarea guidonia)* and carapa (Meliaceae: *Carapa
guianensis).* Seeds were air‑dried at room temperature for 9--11 days.
At intervals, germination was tested, moisture determined, and lipids
extracted. It was found that, like the other recalcitrant seeds, (1)
viability was greatly reduced or lost after 11 days of drying, (2)
percentage changes in individual fatty acids were not related to seed
viability, and (3) results from the differential scanning calorimetry
studies revealed a strong relationship between enthalpy/onset data from
the embryo and cotyledon tissues and loss of viability. Also, silver
maple seeds experienced a 50 percent reduction in viability by day 5 of
drying and retained an axis moisture content over 25 percent throughout
the experiment. However, unlike the other recalcitrant seeds surveyed,
both silver maple and red buckeye had a significant reduction in the
total amount (mg/g) of cotyledon lipids as the experiment progressed.
However, no decrease in the unsaturated/saturated fatty acid ratio was
found, so we conclude that in these species, lipid peroxidation is not a
marker of declining seed viability. Also, red buckeye seeds did not lose
50 percent viability until after day 8 of the experiment, and axis
moisture content fell well below 20 percent as the seeds dried. **(22)**

Deller, Steven C.; Tsai, Tsung-Hsiu (Sue); Marcouiller, David W.;
English, Donald B.K. 2001. **The role of amenities and quality of life
in rural economic growth.** American Journal of Agricultural Economics.
83(2): 352-365.

A structural model of regional economic growth is estimated using data
for 2243 rural US. counties. Five indices designed to capture specific
amenity and quality of life characteristics are constructed using 54
separate indicators. Results suggest that amenity characteristics can be
organized into consistent and meaningful empirical measures that move
beyond ad hoc descriptions of amenities. In addition to insights into
the influence of local characteristics ranging from tax burdens to
income distribution on regional economic growth, results suggest that
predictable relationships between amenities, quality of life, and local
economic performance exist. **(23)**

Hawkins, Leigh K.; Dane, Fenny; Kubisiak, Thomas L.; and others. 2001.
**Linking mapping in a watermelon population segregating for fusarium
wilt resistance.** Journal of American Society for Horticultural
Science. 126(3): 344-350.

Isozyme, randomly amplified polymorphic DNA (RAPD), and simple sequence
repeats (SSR) markers were used to generate a linkage map in an F~2~ and
F~3~ watermelon *(Citrullus lanatus* (Thumb.) Matsum. & Nakai)
population derived from a cross between the fusarium wilt *(Fusarium
oxysporum* f. sp. *niveum)* susceptible "New Hampshire Midget" and
resistant PI 296341‑*FR.* A 11*2*.9 cM RAPD‑based map consisting of 26
markers spanning two linkage groups was generated with F~2~ data. With
F~3~ data, a 139 cM RAPD‑based map consisting of 13 markers covering
five linkage groups was constructed. Isozyme and SSR markers were
unlinked. About 40 percent to 48 percent of the RAPD markers were
significantly skewed from expected Mendelian segregation ratios in both
generations. Bulked segregant analysis and single‑factor analysis of
variance were employed to identify RAPD markers linked to fusarium wilt
caused by races 1 and 2 of *F. oxysporum* f. sp. *niveum.* Current
linkage estimates between the resistance trait and the marker loci were
too large for effective use in a marker‑assisted selection program. (24)

Kabir, Mohammed Firoz; Daud, Wan M.; Khalid, Kaida B.; Sidek, Haji A.A.
2001. **Temperature dependence of the dielectric properties of rubber
wood.** Wood and Fiber Science. 33(2): 233-238.

The effect of temperature on the dielectric properties of rubber wood
was investigated in three anisotropic directions---longitudinal, radial,
and tangential, and at different measurement frequencies. Low frequency
measurements were conducted with a dielectric spectrometer, and high
frequencies used microwave applied with open‑ended coaxial probe
sensors. Dielectric constants and dielectric loss factors were measured
at temperatures from 25 to 100°C. A large dielectric dispersion occurred
at frequencies less than 10 Hz and at temperatures more than 60°C. The
minimum peak value of the dielectric loss factors shifted towards higher
frequencies at higher temperatures in all three grain directions. The
tangential direction showed the highest activation energy. The
dielectric constant decreased as frequency increased from 1 to 10 GHz,
and thereafter remained unchanged with additional frequency increases.
The dielectric constant exhibited higher values at higher temperatures.
The dielectric loss factor showed a peak value at around 10 GHz at 25°C.
**(25)**

Kabir, M.F.; Schmoldt, D.L.; Schafer, M.E. 2001. **Roller-transducer
scanning of wooden pallet parts for defect detection.** In: Thompson,
D.O.; Chimenti, D.E. Review of progress in quantitative nondestructive
evaluation. 20: 1218-1225.

Ultrasonic scanning experiments were conducted on two species of pallet
deckboards using rolling transducers in a pitch‑catch arrangement. Sound
and unsound knots, cross grain, bark pockets, holes, splits, decay, and
wane were characterized using several ultrasound parameters. Almost all
parameters displayed sensitivity to defects distinctly from clear wood
regions---being greatest for unsound knots, bark pockets, decay, holes,
splits, and less for sound knots and cross grain. This study supports
our conjecture that on‑line inspection of wooden pallet parts is
possible using rolling-transducer ultrasonic inspection. **(26)**