COMPASS

Recent Publications

of the Southern Research Station

Winter 2003

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http://www.srs.fs.usda.gov/pubs/

**Wildland-Urban Interface: Intersection of People, Resources, and
Competing Uses**

The term "wildland-urban interface" might sound like a clean alignment,
but the intense competition for limited natural resources increasingly
resembles a professional hockey game. Individuals, groups, developers,
counties, States, small landowners---so many visions conflict over what
constitutes proper use. Published by the Southern Research Station,
*Human Influences on Forest Ecosystems; the Southern Wildland-Urban
Interface Assessment* takes the pulse of people and southern forests as
the South's rapidly increasing population pushes against limited natural
resources. The assessment, edited by Edward A. Macie and L. Annie
Hermansen, opens a dialogue about the complex and evolving nature of
these topics.

Financial ability to get away from the city and suburbia draws people to
move further into the wild, to find their own peace, security, or
adventure. The landscape keeps changing from what "natives" or "locals"
valued when they were raised on that land or when they moved to that
special place. Conflict comes to life at a county zoning meeting or a
department of transportation hearing. Homeowners who choose to build in
heavily wooded, sparsely populated areas can enjoy living in a remote
setting---until a fire threatens lives and structures and challenges
responders' capabilities.

After the 1998 Florida wildfires, the Chief of the USDA Forest Service
identified the wildland-urban interface as one of the main priorities
for the Forest Service in the South. Representatives from the Forest
Service; the Southern Group of State Foresters; universities; the
Cooperative Extension Service, Southern Region; and nonprofit
organizations formed the Southern Wildland-Urban Interface Council. The
group identified key issues and fleshed them out in focus groups that
met in six Southern States. The assessment addresses these topics:

-   Population and demographic trends

-   Economic and tax issues

-   Land use planning and policy issues

-   Urban influences on forests

-   Challenges to forest resource management and conservation

-   Social consequences of change

-   Fire

*Human Influences on Forest Ecosystems; the Southern Wildland-Urban
Interface Assessment*

(GTR SRS-55) is available in print and on the Web
(www.interfacesouth.usda.gov and
([www.srs.fs.fed.us](http://www.srs.fs.fed.us/)). Visit
[www.interfacesouth.usda.gov](http://www.interfacesouth.usda.gov/) to
download a comprehensive literature database and supporting documents.

**27** Macie, Edward A.; Hermansen, L. Annie, eds. 2002. **Human
influences on forest ecosystems: the southern wildland-urban interface
assessment.** Gen. Tech. Rep. SRS-55. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 159 p.

**Southern Pine Ecosystems**

**1** Barnett, J.P.; Dumroese, R.K.; Moorhead, D.J., eds. 2002.
**Proceedings of workshops on growing longleaf pine in containers---1999
and 2001.** Gen. Tech. Rep. SRS--56. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 63 p.

This publication, a compilation of 20 papers concerning nursery
production of longleaf pine seedlings in containers for reforestation,
is a summary of longleaf pine workshops held in 1999 and 2001. The
Longleaf Alliance and the USDA Southern Research Station and Southern
Region Cooperative Forestry organized the first workshop in 1999. It was
held in Jesup, Georgia, on September 21-23, 1999, and 15 papers were
contributed. The University of Georgia Cooperative Extension Service
hosted the second meeting on January 16-18, 2001, in Tifton, Georgia,
and 5 papers are included from that effort. Papers are presented in an
order that reflects a typical growing season and include information on
nursery start-up costs; seed collection, processing, and treatment;
irrigation and fertilization practices; container specifications; target
seedling characteristics; water quality and irrigation concerns;
experiences of small and large operators; pest control; marketing; and
field planting.

**2** Barnett, James P.; Hainds, Mark J.; Hernandez, George A. 2002.
**Interim guidelines for growing longleaf seedlings in containers**
\[Brochure\]**.** Gen. Tech. Rep. SRS-60. Asheville, NC: U.S. Department
of Agriculture, Forest Service, Southern Research Station.

These interim guidelines are designed for producers and users of
longleaf pine container stock. They are not meant to exclude any
container product. The seedling specifications listed in the preferred
category are attainable by the grower and will result in excellent field
survival and early height growth.

**3** Bridgwater, F.E.; Smith, W.D. 2002. **Decline in values of slash
pine stands infected with fusiform rust.** Southern Journal of Applied
Forestry. 26 (3): 134-139.

Losses in product values due to fusiform rust, caused by *Cronartium
quercuum* (Berk.) Miyabe ex Shirai f. sp. fusiforme, were estimated from
four 2.5-yr-old slash pine (*Pinus elliotii* Engelm.) plantations
planted in southern Mississippi over a range of sites with different
growth potential and expected rust infection levels. The percentage of
infected stems ranged from 2.5 percent to 62 percent at age 2.5 years.
The conversion-return method was used to take into account logging,
transportation, and milling costs. Estimated stand values between
infected and noninfected stands were compared to determine the losses in
product value due to fusiform rust. Decline in estimated stand stumpage
values ranged from 5.6 percent to 15.5 percent at age 25 years. Stand
stumpage values at age 25 declined 0.26 percent per 1 percent increase
in stem rust infection at both ages 5 and 2.5. The strong linear
relationship between the percentage of stems infected at age 5 and
decline in stand stumpage values provides a useful tool for land
managers who need to estimate the reduction in value of slash pine
stands at harvest based on rust infection at age 5 years. Combining this
information with estimates of losses from rust-associated mortality and
reduced growth of infected stems (from other studies) permits land
managers to estimate the value of slash pine stands at harvest at early
ages and decide among management alternatives.

**4** Cain, Michael D.; Barnett, James P. 2002. **Effects of early
release on natural versus container loblolly pines 12 years after field
establishment.** Southern Journal of Applied Forestry. 26(4): 173-180.

Genetically improved, container loblolly pine (*Pinus taeda* L.)
seedlings were compared to naturally established loblolly seedlings on a
cutover pine site. Crop pines on 6 of 12 plots were released from woody
and herbaceous competition within a 2 ft radius of each stem. On release
plots, woody competition was controlled by hand-cutting for 5
consecutive years, and herbaceous competition was controlled with
herbicides for 4 consecutive years after pine establishment. Competition
control increased 12 year survival by 68 percentage points for natural
pines and by 47 percentage points for planted pines. Twelve years after
field establishment, mean-tree volume of planted pines was no different
than that of naturally established pines. Nevertheless, volume gains of
150 percent to 200 percent were achieved within regeneration techniques
as a result of release.

**5** Cain, Michael D.; Shelton, Michael G. 2002. **Does prescribed
burning have a place in regenerating uneven-aged loblolly-shortleaf pine
stands?** Southern Journal of Applied Forestry. 26 (3): 117-123.

Before the 1981 growing season, a study was installed in southeastern
Arkansas to examine the effects of three dormant-season burn intervals
(low, moderate, and high frequency), and an unburned treatment on
natural regeneration in uneven-aged stands of loblolly and shortleaf
pines. Merchantable pine basal areas were maintained by harvesting on a
5 or 6 year cutting cycle. When the study began, hardwoods greater than
1 in. d.b.h. were injected with herbicide on all plots. During the next
19 years, there were eight high frequency, four moderate frequency, and
three low frequency prescribed burns. In 1991, the unburned plots
received a single, broadcast-herbicide treatment. Single-tree selection
harvests were conducted in 1982, 1987, 1992,and 1997. Through 1999 (19
years), herbicides applied at 10 year intervals were more effective than
dormant-season burns for enhancing the growth of sub-merchantable pines.
Although recurring winter burns tended to stop the progression of both
pines and hardwoods from seedling to sapling size classes, the data
suggest that properly timed dormant-season burns might be used to secure
natural pine regeneration in selection management.

**6** Collins, Christopher S.; Conner, Richard N.; Saenz, Daniel. 2002.
**Influence of hardwood midstory and pine species on pine bole
arthropods.** Forest Ecology and Management. 164: 211-220.

Arthropod density on the boles of loblolly pines (*Pinus taeda*) was
compared between a stand with and a stand without hardwood midstory and
between a stand of loblolly and shortleaf pines (*P. echinata*) in the
Stephen F. Austin Experimental Forest, Nacogdoches County, Texas, USA
from September 1993 through July 1994. Arthropod density was greatest
(*t* = 5.67, 10 d.f., *P* \< 0.001) in an open pine stand nearly devoid
of hardwood midstory than in a pine stand with dense hardwood midstory.
Loblolly pine had greater (*t* = 2.34, 10.9 d.f., *P* = 0.040) arthropod
densities than shortleaf pine. Vegetative characteristics within a pine
stand rather than bark rugosity appear to be the dominant factor
determining arthropod density on the boles of pines. The red-cockaded
woodpecker (*Picoides borealis*) should benefit from greater abundances
of arthropods on the boles of pines, particularly during the nesting
season. In order to provide prime foraging habitat for the red-cockaded
woodpecker, land managers should consider the vegetative community
structure within foraging habitat.

**7** Franzreb, Kathleen E. 2002. \[Book Review\]. **The red-cockaded
woodpecker: surviving in a**

**fire-maintained ecosystem.** The Condor. 104(3): 701-703.

Southern Station research wildlife biologist Kay Franzreb reviews **The
Red-cockaded Woodpecker: Surviving in a Fire-maintained Ecosystem.**
Richard N. Conner, D. Craig Rudolph, and Jeffrey R. Walters wrote this
comprehensive book on the biology, conservation, and recovery of
*Picoides borealis*.

**8** Glitzenstein, Jeff S.; Streng, Donna R.; Wade, Dale D. 2003.
**Fire frequency effects on longleaf pine (*Pinus palustris* P. Miller)
vegetation in South Carolina and Northeast Florida, USA.** Natural Areas
Journal. 23 (1): 22-37.

Southeastern United States habitats dominated by longleaf pine (*Pinus
palustris* P. Miller) have declined precipitously in area and extent.
Conservation of diverse ground-layer vegetation in these endangered
habitats depends on prescribed fire. While the need for prescribed fire
is now generally accepted, there is disagreement concerning the most
appropriate fire regime. One of the more important variables is
frequency of fire. Several hypothetical relationships between fire
frequency and vascular plant richness and composition are suggested by
the existing literature. Results of two long-term prescribed fire
studies support the hypothesis that burning as frequently as fuels
permit is optimal for maintaining the largest number of native
ground-layer plant species. However, fire frequency effects on species
composition differed between the two studies. Increasing fire frequency
in South Carolina Ultisol flatwoods and wet savannas was associated with
a distinct shift from woody to herbaceous-dominated communities. Herbs,
particularly bunchgrasses and perennial forbs, dominated annual- and
biennial-burn treatment plots, whereas triennial- and quadrennial-burn
plots were shrub-dominated. In contrast, annual and biennial fires did
not produce herbaceous dominated ground-layer vegetation in North
Florida Spodosol flatwoods. Reduced dominance of saw palmetto and
somewhat increased importance of forbs and grasses, particularly
rhizomatous grasses, distinguished the annually burned plots. However,
biennial-and quadrennial-burn plots were similar in composition and did
not differ significantly in species richness at the largest spatial
scale.

**9** Gwaze, D.P.; Bridgwater, F.E.; Williams, C.G. 2002. **Genetic
analysis of growth curves for a woody perennial species, *Pinus taeda*
L.** Theoretical and Applied Genetics. 105: 526-531.

Inheritance of growth curves is critical for understanding evolutionary
change and formulating effi­cient breeding plans, yet has received
limited attention. Growth curves, like other characters that change in
con­cert with development, often have higher heritability than
age-specific traits. This study compared genetic pa­rameters of
height-growth curves with those of age-spe­cific heights for a conifer,
*Pinus taeda* L. Growth curves were fitted with: (1) a linear regression
model; and (2) a non-linear model based on Richards\' function, using
two sources of height data: two six-parent diallel tests as­sessed at age
2 to 10 years, and two tests from a nested mating design with 222
parents assessed at 1 to 25 years. Additive genetic control of
growth-curve parameters was moderate (h^2^ = 0.06 to 0.26) and slightly
lower than that for age-specific heights. Additive variance exceeded
dominance variance for rate and shape parameters, but not for the
asymptote. Genetic correlations among growth-curve parameters were high.
Early selection on height was as efficient as selection on growth-curve
parameters.

**10** Ludovici, Kim H.; Zarnoch, Stanley J.; Richter, Daniel D. 2002.
**Modeling in-situ pine root decomposition using data from a 60-year
chronosequence.** Canadian Journal of Forest Research. 32: 1675-1684.

Because the root system of a mature pine tree typically accounts for
20-30 percent of the total tree biomass, de­composition of large lateral
roots and taproots following forest harvest and re-establishment
potentially impact nutrient supply and carbon sequestration in pine
systems over several decades. If the relationship between stump diameter
and decomposition of taproot and lateral root material, i.e., wood and
bark, can be quantified, a better understanding of rates and patterns of
sequestration and nutrient release can also be developed. This study
estimated decomposition rates from in-situ root systems using a
chronosequence approach. Nine stands of 55- to 70-year-old loblolly pine
*(Pinus taeda* L.) that had been clear-cut 0, 5, 10, 20, 25, 35, 45, 55,
and 60 years ago were identified on well-drained Piedmont soils. Taproot
and lateral root systems were excavated, measured, and weighed. Although
more than 50 percent of the total root mass decomposed during the first
10 years after harvest, field excavations recovered portions of large
lat­eral roots (\>5 cm diameter) and taproots that persisted for more
than 35 and 60 years, respectively. Results indicate that decomposition
of total root biomass, and its component parts, from mature, clear-cut
loblolly pine stands, can be modeled with good precision as a function
of groundline stump diameter and years since harvest.

**11** Rudolph, D. Craig; Conner, Richard N.; Schaefer, Richard R. 2002.
**Red-cockaded woodpecker foraging behavior in relation to midstory
vegetation.** Wilson Bulletin. 114 (2): 235-242.

Red-cockaded woodpeckers (*Picoides borealis*) nest and forage in
pine-dominated forests. Research indicates that substantial hardwood
midstory encroachment is detrimental to red-cockaded woodpecker
populations, although the exact mechanisms are unknown. We examined
foraging behavior in relation to midstory between August 1989 and
February 1990. Red-cockaded woodpeckers foraged at greater heights in
areas of taller and denser midstory in the loblolly-shortleaf pine
(*Pinus taeda* and *P. echinata*, respectively) habitat, but not in
longleaf pine (*P. palustris*) habitat with less-developed midstory
vegetation than typical of loblolly-shortleaf pine habitat. In adition,
red-cockaded woodpeckers concentrated foraging activities in or adjacent
to forest stands or openings with reduced midstory vegetation. Overall,
red-cockaded woodpeckers foraged disproportionately at heights and sites
that minimized their exposure to dense midstory conditions. These
results suggest that ecosystem management, preferably using prescribed
fire, that reduces midstory vegetation will improve foraging habitat for
red-cockaded woodpeckers.

**12** Sanchez, Felipe G.; Bursey, Maurice M. 2002. **Transient nature
of rhizosphere carbon elucidated by supercritical freon-22 extraction
and ^13^C NMR analysis.** Forest Ecology and Management. 169: 177-185.

The region immediately adjacent to established roots of mature trees has
been termed the \"reoccurring rhizosphere\" and it has been hypothesized
that organic matter input from fine root turnover, root exudates, and
sloughing may result in a build up of the soil carbon in this region.
The \"reoccurring rhizosphere\" for first-, second-, and third-order
roots of select loblolly pines *(Pinus taeda* L.) were examined on
sandy, loamy sand and sandy loam soils. A significant carbon build up
next to the root orders was confirmed for the sandy and loamy sand
soils. The carbon build up was substantial (55 percent increase) next to
the first-­order roots of the sandy soil. However, the sandy loam soil
did not display a significant amount of carbon build up next to the root
orders. Extraction of the soil samples with supercritical freon-22
showed that the additional carbon in the \"reoccurring rhizosphere\" was
highly soluble. Approximately 60 percent of the total soil carbon was
extracted from the sandy and loamy sand soils, while approximately 40
percent was extracted from the sandy loam soil. A qualitative comparison
of the extracts by liquid state ^13^C nuclear magnetic resonance showed
that the \"reoccurring rhizosphere\" region had a higher relative
proportion of labile materials (i.e., carbohydrates, proteins, etc.)
than the bulk soil. This information coupled with the high solubility in
supercritical freon-22 suggests that the carbon build up in the
\"reoccurring rhizosphere\" region of loblolly pines may be transient in
nature.

**13** Sullivan, Brian T. 2002. **Evidence for a sex pheromone in bark
beetle parasitoid**

***Roptrocerus xylophagorum*.** Journal of Chemical Ecology. 28(5):
1045-1063.

Male *Roptrocerus xylophagorum* (Ratzeburg) (Hymenoptera: Ptero­malidae)
exhibited courtship and mating behaviors including wing fanning,
an­tennation, mounting, and copulation attempts when exposed to glass
bulb decoys coated with a whole-body extract of females in hexane,
acetone, or methanol. Activity of extract-treated decoys declined
gradually over one week. Males responded much less strongly to
freeze-killed female cadavers extracted with solvents than to
unextracted cadavers; treatment of extracted cadavers with fe­male
extract restored male responses. The pheromone was found to be equally
present over the surface of both the abdomen and head/thorax of females,
and the origin of the pheromone could not be conclusively localized to
any single body region. The activity of pheromone on females increased
between day 1 and days 3-5 following eclosion; otherwise, pheromone
activity was not significantly af­fected by either female age or mating.
Males were arrested within the zone of a glass surface on which females
had walked, suggesting that the pheromone might be substrate-borne.
Recent exposure to females reduced male responsive­ness, but
responsiveness was fully restored after a few hours of male isolation
from females. When hexane extracts of whole females were fractionated on
silica gel, the pheromone\'s activity was largely recovered with the
first, most non-polar fraction. Female extracts and fractions were
analyzed by coupled gas chromatography-mass spectrometry. Cuticular
hydrocarbon alkanes were iden­tified as the extract components whose
concentrations correlated best with male responses. Evidence of the
pheromone\'s long persistence, low volatility, low polarity, and
presence over the insect\'s entire body surface further supported the
hypothesis that the pheromone was composed of one or more cuticular
hydrocarbons.

**Wetlands, Bottomlands, and Streams**

**14** Smith, David R.; Schiff, Nathan M. 2001. **A new species of
*Xiphydria* latreille (Hymenoptera: Xiphydriidae) reared from river
birch, *Betula nigra* L., in North America.** Proceedings of the
Entomological Society of Washington. 103 (4): 962-967.

*Xiphydria decem*, n. sp., is described and separated from other North
American species. It was reared from branches of river birch, *Betula
nigra* L. (Betulaceae) in Illinois.

**15** Sun, G.; McNulty, S.G.; Amatya, D.M. \[and others\]. 2002. **A
comparison of the watershed hydrology of coastal forested wetlands and
the mountainous uplands in the Southern U.S.** Journal of Hydrology.
263: 92-104.

Hydrology plays a critical role in wetland development and ecosystem
structure and functions. Hydrologic responses to forest management and
climate change are diverse in the Southern United States due to
topographic and climatic differences. This paper presents a comparison
study on long-term hydrologic characteristics (long-term seasonal runoff
patterns, water balances, storm flow patterns) of three watersheds in
the Southern United States. These three watersheds represent three types
of forest ecosystems commonly found in the Lower Atlantic Coastal Plain
and the Appalachian Upland Mountains. Compared to the warm, flat, and
shallow groundwater dominated pine flatwoods on the coast, the inland
upland watershed was found to have signifi­cantly higher water yield,
Precipitation/Hamon\'s potential evapotranspiration ratio (1.9 for
upland vs 1.4 and 0.9 for wetlands), and runoff/precipitation ratio
(0.53 ± 0.092 for upland vs 0.30 ± 0.079 and 0.13 ± 0.094 for wetlands).
Streamflow from flatwoods watersheds generally are discontinuous most of
the years, while the upland watershed showed continuous flows in most
years. Stormflow peaks in a cypress-pine flatwoods system were smaller
than that in the upland watershed for most cases, but exceptions
occurred under extreme wet conditions. Our study concludes that climate
is the most important factor in determining the watershed water balances
in the Southern United States. Topography affects streamflow patterns
and stormflow peaks and volume, and is the key to wetland development in
the Southern United States.

**Mountain and Highland Ecosystems**

**16** Greenberg, Cathryn H. 2002. **Response of white-footed mice
(*Peromyscus leucopus*) to coarse woody debris and microsite use in
Southern Appalachian treefall gaps.** Forest Ecology and Management.
164: 57-66.

The influence of treefall gaps and coarse woody debris (CWD) on
white-footed mouse (*Peromyscus leucopus*) abundance was tested
experimentally during 1996-1999 in a Southern Appalachian hardwood
forest. I compared the relative abundance and body size of *P. leucopus*
among unsalvaged gaps that were created by wind disturbance and retained
high CWD levels, salvage logged gaps where fallen and damaged tree boles
had been removed, and closed-canopy controls. I also tested the relative
use by mice of four microsite types: CWD, pits, woody brush, and open
ground. One-hundred and forty-one *P. leucopus* were captured 310 times
during the study. There were no differences in capture success, body
size, or sex ratio among treatments before or after salvage logging, but
abundance varied among years. Capture success was higher at traps set
adjacent to CWD (*P* \< 0.05) and in pits (*P* \< 0.10) than at traps
set under brush or on open ground. In the Southern Appalachians,
windthrow-created canopy gaps and associated microsites do not affect
habitat use by *P. leucopus* at a landscape level (as measured by
relative abundance among treatments), but CWD influences the
microdistribution of *P. leucopus* where it is present.

**17** Knoepp, Jennifer D.; Vose, James M. 2002. **Quantitative
comparison of *in situ* soil CO~2~ flux measurement methods.** Resch.
Pap. SRS-28. Asheville, NC: U.S. Department of Agriculture, Forest
Service, Southern Research Station. 11 p.

Development of reliable regional or global carbon budgets requires
accurate measurement of soil CO~2~ flux. We conducted laboratory and
field studies to determine the accuracy and comparability of methods
commonly used to measure *in situ* soil CO~2~ fluxes. Methods compared
included CO~2~ traps; a multichamber open dynamic system (OC) with an
infrared gas analyzer; and a headspace analysis system, with gas
chromatograph with circulating fan (GCF) and gas chromatograph without
circulating fan (GC), measuring changes in headspace CO~2~ concentration
using a gas chromatograph. In the laboratory, we compared NaOH, OC, GCF,
and GC using sand-filled cylinders to simulate a soil system. Three
concentrations of standard CO~2~ gas (representing low, medium, and high
soil-CO~2~ flux rates) entered the cylinders through individually
monitored flow meters. Flux rates measured using the OC method equaled
the actual CO~2~ flux at all three CO~2~ concentrations. Flux rates
determined with GC and GCF were \< 55 percent of the actual flux rate.
The percent of actual CO~2~ flux measured increased with increasing
CO~2~ concentrations. At all concentrations, NaOH collected between 40
and 47 percent of CO~2~ entering the system. A field study was conducted
to verify laboratory results and allow comparison with the soda lime
trap (SODA) method. In laboratory and field studies, all methods
detected significant differences in flux rates among the standard CO~2~
concentrations and field sites. Regression analyses showed good
relationships between NaOH, SODA, and GC methods with flux rates
measured using the OC methods (r^2^ \>= 0.78). Slope values for these
regression equations ranged from 0.34 for NaOH to 0.54 for GC and SODA.
These results suggest that data collected using the other methods could
be standardized to OC flux rates. However, because methodological
differences significantly affect CO~2~ flux measurements, care should be
used in applying these relationships.

**18** Oak, Steven W. 2002. **From the Bronx to Birmingham: impact of
chestnut blight and management practices on forest health risks in the
Southern Appalachian Mountains.** Journal of the American Chestnut
Foundation. 16(1): 32-41.

Southern Appalachian forest landscapes evoke images of the primeval
forest in many people today. Indeed, most vegetation components in these
forests have been present in varying mixtures and distributions for at
least 58 million years. However, the only thing constant about these
landscapes has been change. Advancing and retreating ice sheets,
drought, flood, wind, and fire all served to shape forest composition
and structure. Irrepressible as these forces are, people have been
perhaps the most important change agents since arriving in the region at
least 9,000 years ago. In this context, the types and sequence of
human-influenced disturbances since the middle of the 19th century have
resulted in Southern Appalachian forests that bear little resemblance in
terms of composition and structure to any that have existed in the past.
These disturbances include the widespread use of fire, first by native
people and then by European settlers; land clearing and agriculture
followed by abandonment of marginally productive lands; widespread and
sometimes abusive logging to supply fuel and building materials to a
growing Nation; industrialization and concurrent urbanization; and the
implementation of aggressive fire suppression.

**19** Prestemon, Jeffrey P.; Pye, John M.; Abt, Karen Lee \[and
others\]. 2000. **Market definition for hardwood timber in the Southern
Appalachians.** In: Munn, I.A.; Bullard, S.H.; Grado, S.C.; Grebner,
D.L., eds. Proceedings of the 1999 southern forest economics workshop.
Starkville, MS: Mississippi State University: 91-98.

Direct estimation of aggregate hardwood supply is seriously complicated
by the diversity of prices, species, and site conditions in hardwood
stands. An alternative approach is to aggregate regional supply based on
stumpage values of individual stands, arguably the real driver of
harvest decisions. Complicating this approach is that species-specific
prices are only available for logs delivered to the mill. To derive
stumpage values, delivered prices must be reduced by the costs of
harvesting and transport to the mill; hence, the spatial characteristics
of the market may be important in defining the aggregate timber supply
responsiveness to price. This paper represents an intermediate step in
estimating an aggregate supply model for hardwood timber, where we
tested the more limited hypothesis that harvest probability and hence
stand age is positively related to timber value and negatively related
to factors which reduce timber value. We regressed stand age on
distances to three types of mills, slope of site, distance from the
stand to the nearest road, site quality, and broad management type. We
found that stand age increases with distance from mills for NIPF-,
industry-, and government-managed stands in the Southern Appalachians.
Stand age is negatively related to site quality, positively related to
slope of stand, and not significantly affected by distance from the
stand to the nearest road. Stand ages also vary by broad management
type.

###### 

###### **Large-Scale Assessment and Modeling**

**20** Bowker, J.M.; English, Donald B.K. 2002. **Mountain biking at
Tsali: an assessment of users, preferences, conflicts, and management
alternatives.** Gen. Tech. Rep. SRS-59. Asheville, NC: U.S. Department
of Agriculture, Forest Service, Southern Research Station. 28 p.

Tsali Recreation Area is part of the Cheoah Ranger District of the
Nantahala National Forest. Overlooking the Great Smoky Mountains, it is
one of the premier mountain biking sites in the Eastern United States.
The results of a 13-month on-site survey of 1,359 Tsali visitors examine
the demographics, behavior, current trip profile, and attitudes toward
user fees, current management policies, and future management
alternatives. More than 70 percent of visitors were male, 96 percent
were white, 85 percent had attended college, 90 percent were between the
ages of 20 and 49, and more than 60 percent had incomes over \$50,000.
Sixty percent of the visitors had four or more years of experience; 16
percent were beginners. Visitors averaged 21 biking trips totaling 59
days yearly, averaging 3 visits to Tsali. Fifty-five percent were
first-time visitors, while 80 percent said Tsali was their \"favorite
place\" to ride. Trail surface and congestion were the most important
site attributes to visitors. Surfaces rated high in performance,
indicating that management practices are successful. Congestion on
trails rated slightly less than \"good,\" suggesting management
consideration. Site facilities rated \"good\" or better on average.
Parking and security were ranked highly for both performance and
importance. Toilet facilities ranked the lowest in performance but high
in importance, suggesting another area for management consideration.
Most visitors (95 percent) agreed that fees are a \"good tool to manage
public recreation areas,\" in general and at Tsali. Visitors
overwhelmingly supported future management alternatives that proposed
more trail miles, even though these were combined with fee increases.

**21** Brockway, Dale G.; Gatewood, Richard G.; Paris, Randi B. 2002.
**Restoring fire as an ecological process in shortgrass prairie
ecosystems: initial effects of prescribed burning during the dormant and
growing seasons.** Journal of Environmental Management. 65: 135-152.

Prior to Anglo-European settlement, fire was a major ecological process
influencing the structure, composition, and productivity of shortgrass
prairie ecosystems on the Great Plains. However during the past 125
years, the frequency and extent of grassland fire has dramatically
declined as a result of the systematic heavy grazing by large herds of
domestic cattle and sheep, which reduced the available levels of fine
fuel and organized fire suppression efforts that succeeded in altering
the natural fire regime. The greatly diminished role of recurrent fire
in these ecosystems is thought to be responsible for ecologically
adverse shifts in the composition, structure and diversity of these
grasslands, leading specifically to the rise of ruderal species and
invasion by less fire-tolerant species. The purpose of this study was to
evaluate the ecological effects of fire season and frequency on the
shortgrass prairie and to determine the means by which prescribed fire
can best be restored in this ecosystem to provide the greatest benefit
for numerous resource values. Plant cover, diversity, biomass and
nutrient status, litter cover, and soil chemistry were measured prior to
and following fire treatments on a buffalograss-blue grama shortgrass
prairie in northeastern New Mexico. Dormant-season fire was followed by
increases in grass cover, forb cover, species richness, and
concentrations of foliar P, K, Ca, Mg, and Mn. Growing-season fire
produced declines in the cover of buffalograss, graminoids, and forbs,
and increases in litter cover and levels of foliar P, K, Ca, and Mn.
Although no changes in soil chemistry were observed, both fire
treatments caused decreases in herbaceous production, with standing
biomass resulting from growing-season fire \~600 kg/ha and
dormant-season fire \~1200 kg/ha, compared with controls \~1800 kg/ha.
The initial findings of this long-term experiment suggest that
dormant-season burning may be the preferable method for restoring fire
in shortgrass prairie ecosystems where fire has been excluded for a
prolonged time period.

**22** Clark, Mark M.; Meller, Russell D.; McDonald, Timothy P. 2000.
**A three-stage heuristic for harvest scheduling with access road
network development.** Forest Science. 46(2): 204-218.

In this article we present a new model for the scheduling of forest
harvesting with spatial and temporal constraints. Our approach is unique
in that we incorporate access road network development into the harvest
scheduling selection process. Due to the difficulty of solving the
problem optimally, we develop a heuristic that consists of a solution
construction stage and two solution improvement stages. We call our
approach INROADS and compare it to three other approaches by employing
hypothetical example problems with 225 stands (or cut blocks) over a
three-period planning horizon. Thirteen example forests that vary in
terms of stand value and spatial dispersion are used to evaluate our
heuristic, which outperforms the other approaches tested.

**23** English, Donald B.K.; Kocis, Susan M.; Zarnoch, Stanley J.;
Arnold, J. Ross. 2002. **Forest Service national visitor use monitoring
process: research method documentation.** Resch. Pap. SRS-57. Asheville,
NC: U.S. Department of Agriculture, Forest Service, Southern Research
Station. 14 p.

In response to the need for improved information on recreational use of
National Forest System lands, the authors have developed a nationwide,
systematic monitoring process. This report documents the methods they
used in estimating recreational use on an annual basis. The basic unit
of measure is exiting volume of visitors from a recreation site on a
given day. Sites are stratified by type. Days are stratified by expected
volume of exiting recreation visitors. A double sampling strategy is the
primary means used to obtain measures of exiting recreation traffic.
Where possible, observable counts of other measures highly correlated
with visitation, such as fee envelopes, ski lift tickets, or
concessionaire reports, are used to reduce variation in visitation
estimates. In addition to showing how sampling units were defined, the
authors also provide calculations they used in developing estimators for
the mean and variance of visitation.

**24** Kilgo, John C.; Gartner, David L.; Chapman, Brian R. \[and
others\]. 2002. **A test of an expert-based bird-habitat relationship
model in South Carolina.** Wildlife Society Bulletin. 30(3): 783-793.

Wildlife-habitat relationships models are used widely by land managers
to provide infor­mation on which species are likely to occur in an area
of interest and may be impacted by a proposed management activity. Few
such models have been tested. We used recent avian census data from the
Savannah River Site, South Carolina to validate BIRDHAB, a geographic
information system (GIS) model developed by United States Forest Service
resource managers to predict relative habitat quality for birds at the
stand level on nation­al forests in the southeastern United States.
BIRDHAB is based on the species-habitat matrices presented by Hamel
(1992). Species-specific accuracy rates for BIRDHAB pre­dictions (the
percentage of all stands in which a species was predicted correctly as
pres­ent or absent) ranged from 33.6-93.0 percent, with a mean of
67.4±17.3 percent (SD, n=46 species). Accuracy was \>90 percent for 5
species, but \<50 percent for 9 species. BIRDHAB performed well (P
\<0.05) in predicting presence-absence of 32 species. Generally, the
model was more accurate in predicting presence-absence for habitat
specialists than for generalists. Habi­tat-specific accuracy rates (the
percentage of species for which a habitat\'s prediction was correct)
ranged from 52.7-92.7 percent, with a mean of 71.8±(SD) 9.8 percent
(n=26 habitat types). BIRDHAB was a useful tool for many of the species
that we tested, but it had no predic­tive ability for many others. Such
species-specific variation in accuracy probably is common among
wildlife-habitat relationships models, reinforcing the need for thorough
testing before these models are used in land-use planning.

**25** Ludovici, Kim H.; Zarnoch, Stanley J.; Richter, Daniel D. 2002.
**Modeling in-situ pine root decomposition using data from a 60-year
chronosequence.** Canadian Journal of Forest Research. 32: 1675-1684.

Because the root system of a mature pine tree typically accounts for
20-30 percent of the total tree biomass, de­composition of large lateral
roots and taproots following forest harvest and re-establishment
potentially impact nutrient supply and carbon sequestration in pine
systems over several decades. If the relationship between stump diameter
and decomposition of taproot and lateral root material, i.e., wood and
bark, can be quantified, a better understanding of rates and patterns of
sequestration and nutrient release can also be developed. This study
estimated decomposition rates from in-situ root systems using a
chronosequence approach. Nine stands of 55- to 70-year-old loblolly pine
*(Pinus taeda* L.) that had been clear-cut 0, 5, 10, 20, 25, 35, 45, 55,
and 60 years ago were identified on well-drained Piedmont soils. Taproot
and lateral root systems were excavated, measured, and weighed. Although
more than 50 percent of the total root mass decomposed during the first
10 years after harvest, field excavations recovered portions of large
lat­eral roots (\>5 cm diameter) and taproots that persisted for more
than 35 and 60 years, respectively. Results indicate that decomposition
of total root biomass, and its component parts, from mature, clear-cut
loblolly pine stands, can be modeled with good precision as a function
of groundline stump diameter and years since harvest.

**26** Luxmoore, Robert J.; Hargrove, William W.; Tharp, M. Lynn \[and
others\]. 2002. **Addressing multi-use issues in sustainable forest
management with signal-transfer modeling.** Forest Ecology and
Management. 165: 295-304.

Management decisions concerning impacts of projected changes in
environmental and social conditions on multi-use forest products and
services, such as productivity, water supply or carbon sequestration,
may be facilitated with signal-transfer modeling. This simulation method
utilizes a hierarchy of simulators in which the integrated responses
(signals) from smaller- scale process models are transferred and
incorporated into the algorithms of larger spatial- and temporal-scale
models of ecological and economic phenomena. Several innovative
procedures germane to multi-issue sustainable forest management have
been initiated in our signal-transfer modeling development for forests
of the southeastern United States. These developments include response
surface interpolation for multi-factor signal-transfer, use of loblolly
pine modeling to infer the growth of other southern pines, determination
of soil nutrient limitations to productivity, multivariate clustering as
a spatial basis for defining land units relevant to forest management,
and variance propagation through the modeling hierarchy. Algorithms for
larger scale phenomena are shown to constrain the variance introduced
from a smaller-scale in a simulation of ambient ozone exposure effects
on loblolly pine timber yield. Outputs of forest variables are frequency
distributions that may be statistically compared for alternative
environmental or management scenarios.

**27** Macie, Edward A.; Hermansen, L. Annie, eds. 2002. **Human
influences on forest ecosystems: the southern wildland-urban interface
assessment.** Gen. Tech. Rep. SRS-55. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 159 p.

This publication provides a review of critical wildland-urban interface
issues, challenges, and needs for the Southern United States. Chapter
topics include population and demographic trends; economic and tax
issues; land use planning and policy; urban effects on forest
ecosystems; challenges for forest resource management and conservation;
social consequences of change; fire; and themes, research, and
information needs for the wildland-urban interface.

**28** McCarty, John P.; Levey, Douglas J.; Greenberg, Cathryn H.;
Sargent, Sarah. 2002. **Spatial and temporal variation in fruit use by
wildlife in a forested landscape.** Forest Ecology and Management. 164:
277-291.

We monitored production and removal rates of fruit from 22 common plant
species over 2 years in five habitats of a managed landscape in South
Carolina (USA). Our long-term goal is to determine the importance of
fruit as a resource for vertebrates and to provide recommendations for
management of key species and habitats. This study lays the foundation
for that goal by documenting fruit production and availability,
variation in use by wildlife, and how these factors vary by plant
species, habitat, and season. Six species produced \>1 kg dry mass of
pulp per hectare per year. Vertebrates consumed 250 percent of fruits in
17 of the 22 plant species. Fruit loss to insects and microbes was
generally small and varied significantly among seasons, being lowest in
fall and winter. The length of time ripe fruit survived on plants varied
among species from 3 to 165 days. Survival time of fruits did not vary
significantly among habitats but was significantly shorter in the summer
than in fall or winter. Approximately, half the species produced fruit
in the fall and winter, and these fruits were primarily consumed by
over-wintering wildlife. This pattern is inconsistent with the general
belief that fruit production in the Eastern United States is timed to
correspond with periods of high bird abundance during fall migration.
Production and consumption of winter fruits deserves further attention
from forest managers, as relatively little other food is available in
winter, energy demands of over-wintering birds are high, and current
management practices often reduce fruit availability of key species
(e.g., *Myrica cerifera*). We suggest that fruit is more important than
generally realized in maintaining vertebrate diversity in temperate
forests and that the focus of managers on hard mast production should be
broadened to include fruiting plants.

**29** Prestemon, Jeffrey P.; Pye, John M.; Butry, David T. \[and
others\]. 2002. **Understanding broadscale wildfire risks in a
human-dominated landscape.** Forest Science. 48(4): 685-693.

Broadscale statistical evaluations of wildfire incidence can answer
policy- relevant questions about the effectiveness of microlevel
vegetation management and can identify subjects needing further study. A
dynamic time series cross-sectional model was used to evaluate the
statistical links between forest wildfire and vegetation management,
human land use, and climatic factors in Florida counties. Four forest
wildfire risk functions were estimated: one for fires regardless of
ignition source, and three others for fires of specific ignition
sources: arson, lightning, and accident (unintentional anthropogenic).
Results suggest that current wildfire risk is negatively related to
several years of past wildfire and very recent site prep burning, and
risk is positively related to pulpwood removals. The effect of
traditional prescribed burning on wildfire risk varies by ignition
source. El Niño-Southern Oscillation (ENSO) sea surface temperature
(SST) anomalies were also significantly linked to forest wildfire risk,
but a measure of the wildland-urban interface was not significant.
Although these county-level results hold promise for aggregate risk
assessment, modeling at finer spatial and temporal scales might further
enhance our understanding of how land managers can best reduce the
longer term risk of catastrophic wildfire damages.

**30** Rials, Timothy G.; Kelley, Stephen S.; So, Chi-Leung. 2002. **Use
of advanced spectroscopic techniques for predicting the mechanical
properties of wood composites.** Wood and Fiber Science. 34(3): 398-407.

Near infrared (NIR) spectroscopy was used to characterize a set of
medium-density fiberboard (MDF) samples. This spectroscopic technique,
in combination with projection to latent structures (PLS) modeling,
effectively predicted the mechanical strength of MDF samples with a wide
range of physical properties. The stiffness, strength, and internal bond
properties of the MDF sample could be predicted from the NIR spectra of
the MDF surface. The technique is very rapid and provides molecular
level insight on subtle changes in the properties of the MDF panels. The
results highlight the potential value of NIR spectroscopy for process
monitoring and quality control applications.

**31** Riitters, Kurt H.; Wickham, James D.; O'Neill, Robert V. \[and
others\]. 2002. **Fragmentation of Continental United States Forests.**
Ecosystems. 5: 815-822.

We report a multiple-scale analysis of forest fragmentation based on
30-m (0.09 ha pixel^-1^) land-cover maps for the conterminous United
States. Each 0.09-ha unit of forest was classified according to
fragmentation indexes measured within the surrounding landscape, for
five landscape sizes including 2.25, 7.29, 65.61, 590.49, and 5314.41
ha. Most forest is found in fragmented landscapes. With 65.61-ha
landscapes, for example, only 9.9 percent of all forest was contained in
a fully forested landscape, and only 46.9 percent was in a landscape
that was more than 90 percent forested. Overall, 43.5 percent of forest
was located within 90 m of forest edge and 61.8 percent of forest was
located within 150 m of forest edge. Nevertheless, where forest existed,
it was usually dominant---at least 72.9 percent of all forest was in
landscapes that were at least 60 percent forested for all landscape
sizes. Small (less than 7.29 ha) perforations in otherwise continuous
forest cover accounted for about half of the fragmentation. These
results suggest that forests are connected over large regions, but
fragmentation is so pervasive that edge effects potentially influence
ecological processes on most forested lands.

**32** Stanturf, J.A.; Madsen, P. 2002. **Restoration concepts for
temperate and boreal forests of North America and Western Europe.**
Plant Biosystems. 136(2): 143-158.

Throughout the boreal and temperate zones, forest restoration efforts
attempt to counteract negative effects of conversion to other land use
(afforestation and remediation) and disturbance and stress on existing
forests (rehabilitation). Appropriate silvitultural practices can be
designed for any forest restoration objective. Most common objectives
include timber, wildlife habitat for game species, or aesthetics.
Increasingly, other objectives are considered, including carbon
sequestration, biological diversity, non-game mammals and birds,
endangered animals and plants, and protection of water quality and
aquatic resources, and recreation. Plantation forestry remains the most
effective approach to restoration of forest cover to large areas, and
recent trends toward more complex plantations are explored.
Rehabilitation of degraded forests increasingly relies on
re-establishing natural disturbance regimes and emphasizes
"close-to-nature" approaches to regeneration and stand management. The
objectives of this paper are to clarify concepts of forest restoration
and to present examples of restoration activities in temperate and
boreal forests of North America and Western Europe.

**33** Sword, Mary A.; Tiarks, Allan E. 2002. **Local soils information
needed to define the root zone in process models on the Gulf Coastal
Plain.** Gen. Tech. Rep. SRS-58. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 15 p.

We combined published information and our own experimental results from
the Gulf Coastal Plain to evaluate how soil aeration and strength
interact with loblolly pine root growth. Our results demonstrate that
soil aeration and strength differ by soil series and year and are
subject to vertical and horizontal spatial variation. Comparison of
loblolly pine root phenology and seasonal redox potential indicates that
oxygen is frequently limiting to new root growth. The strength of these
soils may also restrict loblolly pine root growth. Physiological process
models that predict southern pine productivity should apply accurate
calculations of plant-available soil in simulations of potential root
zone water storage and plant-available water. We propose a conceptual
root zone submodel that predicts the volume of plant-available soil with
soil aeration, strength, and water retention by horizon. Model
parameters are components of the Natural Resources Conservation Service
(NRCS) Soil Interpretation Record (SIR) database collected across the
United States.

Inventory and Monitoring

**34** Bechtold, William A.; Mielke, Manfred E.; Zarnoch, Stanley J.
2002. **Comparison of field methods and models to estimate mean crown
diameter.** Northern Journal of Applied Forestry. 19(4): 177-182.

The direct measurement of crown diameters with logger's tapes adds
significantly to the cost of extensive forest inventories.\
We undertook a study of 100 trees to compare this measurement method to
four alternatives---two field instruments, ocular estimates, and
regression models. Using the taping method as the standard of
comparison, accuracy of the tested alternative was adequate for softwood
species, but short of the specified measurement quality objective for
estimating the mean crown diameter of hardwoods. Due to savings in field
costs, ocular estimation and regression models were the best
alternatives to direct measurement with logger's tapes.

**35** Bentley, James W.; Johnson, Tony G.; Howell, Michael. 2002.
**Arkansas' timber industry---an assessment of timber produce output and
use, 1999.** Resour. Bull. SRS-79. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 40 p.

In 1999, roundwood output from Arkansas' forests totaled 692 million
cubic feet. Mill byproducts generated from primary manufacturers were
290 million cubic feet. Almost all plant residues were used, primarily
for fuel and fiber products. Saw logs were the leading roundwood product
at 320 million cubic feet; pulpwood ranked second at 285 million cubic
feet; veneer logs were third at 84 million cubic feet. The number of
primary processing plants was 336 in 1999. Receipts for those mills
totaled 681 million cubic feet.

**36** Bragg, Don C. 2002. **A system to derive optimal tree diameter
increment models from the Eastwide Forest Inventory Data Base (EFIDB).**
Southern Journal of Applied Forestry. 26(4): 214-221.

This article is an introduction to the computer software used by the
Potential Relative Increment (PRI) approach to optimal tree diameter
growth modeling. These DOS programs extract qualified tree and plot data
from the Eastwide Forest Inventory Data Base (EFIDB), calculate relative
tree increment, sort for the highest relative increments by diameter
class, and generate an ASCII file for post-processing in any software
package capable of customized ordinary least squares regression.

**37** Hartsell, Andrew J. 2002. **Forest statistics for southeast
Alabama, 2000.** Resour. Bull. SRS-66. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station. 59 p.

This report summarizes a 2000 inventory of the forest resources of a
21-county area of Alabama. Major findings are highlighted in text and
graphics; detailed data are presented in 49 tables.

**38** Howell, Michael; Wright, Robert. 2002. **Tennessee's timber
industry---an assessment of timber product output and use, 1999.**
Resour. Bull. SRS-76. Asheville, NC: U.S. Department of Agriculture,
Forest Service, Southern Research Station. 39 p.

In 1999, roundwood output from Tennessee's forests was 325 million cubic
feet. Mill byproducts generated from primary manufacturers totaled 125
million cubic feet. Ninety percent of the plant residues were used
primarily for fuel and fiber products. Saw logs were the leading
roundwood product at 185 million cubic feet; pulpwood ranked second at
121 million cubic feet; other industrial products were third at 13
million cubic feet. There were 451 primary processing plants operating
in Tennessee in 1999. Total receipts amounted to 306 million cubic feet.

Foundation Programs

**39** Bragg, Don C. 2002. Review of **SnagIt, version 6.1 for
Windows**. Bulletin of the Ecological Society of America**.** 83(4):
255-256.

Southern Station research forester Don Bragg reviews SNAGIT, Version 6.1
for Windows. He comments on the increasing demand for scientists to
utilize digital files to publish their research. Bragg considers SNAGIT
an effective and affordable screen capture utility that has evolved into
a multi-feature graphics package.

**40** Grace, J.M., III. 2002. **Control of sediment export from the
forest road prism.** Transactions of the American Society of
Agricultural Engineers. 45 (4): 1127-1132.

The effectiveness of four road turn-out ditch treatments (vegetation,
rip-rap, sediment fences, and settling basins) in reducing sediment
export to the forest floor was evaluated. These four runoff control
methods are commonly prescribed to control forest road runoff and
sediments. The study utilized runoff samplers, runoff diversion walls,
sediment filter bags, and erosion stakes to evaluate runoff
concentration reductions through the treatments and sediment export
downslope of the treatments. Settling basin, sediment fence, and
vegetation treatments had no significant differences in runoff
concentration reductions, which averaged more than 40 percent. The
rip-rap was significantly less effective at reducing runoff
concentration than were either the vegetation or sediment fence. The
sediment basins were very effective during smaller storm events, but not
during the largest storms, when they overflowed. The sediment basin
exported the least amount of smaller-sized sediment that is likely to be
delivered to stream systems.

**41** Wilson, A.D.; Lester, D.G. 2002. **Trench inserts as long-term
barriers to root transmission for control of oak wilt.** Plant disease.
86 (10): 1067-1074.

Physical and chemical barriers to root penetration and root grafting
across trenches were evaluated for their effectiveness in improving
trenches as barriers to root transmission of the oak wilt fungus in live
oaks. Four trench insert materials were tested, including
water-permeable Typar and Biobarrier, and water-impenetrable Geomembrane
of two thicknesses. Systemic fungicide treatments of trees immediately
outside of trenches also were tested. In the first several years
following trench installation, an abundance of small adventitious roots
commonly formed from roots severed by trenching. These roots provided
opportunities for initiation of root grafts across trenches in
subsequent years. Although trench inserts did not significantly improve
trenches during the first three ears following trench installation,
water-permeable inserts did effectively improve the performance of
trenches beyond the third post-trenching year, when trenches are
normally effective, and extended trench longevity indefinitely. The
water-permeable inserts were more effective root barriers because they
did not direct root growth from the point of root contact. The
water-impermeable materials, however, did tend to direct root growth
around these barriers, leading to the development of new root graft
connections and associated oak wilt root transmission across the trench.
The additional cost of trench inserts above trenching costs was
justified in urban and rural homestead sites, where high value landscape
trees required more protection and additional retrenching costs were
avoided.