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Restoration and Winter Avian Use of Isolated Prairies in
Eastern Texas
D. Craig Rudolph1,*, Dave E. Plair2, Dan Jones3, J. Howard Williamson1,
Clifford E. Shackelford4, Richard R. Schaefer1, and Joshua B. Pierce1
Abstract - Numerous isolated prairies exist, or existed, on the West Gulf Coastal Plain
east of the main distribution of the prairie ecosystem. Changing land-use patterns and
suppression of wildfire have destroyed almost all of these small prairie occurrences. Intensified
restoration and management of degraded prairie habitat on the Sam Houston National
Forest in southeastern Texas have been ongoing since approximately 2004. As a result,
encroaching woody vegetation has been substantially reduced, and a vegetation structure
consistent with prairie habitat has been restored. Beginning in 2008, we conducted winter
bird surveys on these prairies with the objective of quantifying avian use, especially by
grassland sparrows of the genus Ammodramus. With the improvement in prairie structure,
winter use of these sites by Ammodramus spp. was rapidly established, typically following
the first post-restoration growing season. Ammodramus henslowii (Henslow’s Sparrow), a
species of conservation concern, responded particularly dramatically. These results demonstrate
that aggressive restoration of prairie remnants on the West Gulf Coastal Plain can
rapidly reestablish prairie habitat and facilitate re-colonization by at least some avian species
characteristic of prairie habitats.
Introduction
Numerous isolated prairies occur, or once occurred, on the West Gulf Coastal
Plain (WGCP) in eastern Texas, Louisiana, and southern Arkansas (Diggs et al.
2006, MacRoberts and MacRoberts 2004). In southeastern Texas, many small
isolated prairies occur on the Sam Houston National Forest (SHNF) in Liberty,
Montgomery, San Jacinto, and Walker counties (Carr 1993). These prairies are
embedded within the pineywoods vegetation area on sites where a combination of
edaphic conditions and a frequent fire regime historically inhibited establishment
of woody vegetation (Diggs et al. 2006). Loss of isolated prairies on the WGCP has
been extensive since the arrival of Europeans, primarily due to land-use changes,
fire suppression, and silvicultural practices (MacRoberts and MacRoberts 2004).
MacRoberts and MacRoberts (1997) estimated that the loss of isolated prairie communities
is in excess of 99% in Louisiana alone, and there is no reason to infer a
lower figure for eastern Texas. Many of the prairie occurrences on the SHNF became
degraded due to the lack of consistent and focused management to preserve
1USDA, Forest Service, Southern Research Station, 506 Hayter Street, Nacogdoches, TX
75965. 2USDA, Forest Service, Sam Houston National Forest, 394 FM 1375, New Waverly,
TX 77358. 3Texas Parks and Wildlife Department, PO Box 1003, Huntsville, TX 77342.
4Texas Parks and Wildlife Department, 506 Hayter Street, Nacogdoches, TX 75965. *Corresponding
author - crudolph01@fs.fed.us.
Manuscript Editor: Jerry Cook
Proceedings of the 5th Big Thicket Science Conference: Changing Landscapes and Changing Climate
2014 Southeastern Naturalist 13(Special Issue 5):52–63
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them. Fire suppression, agricultural impacts, grazing, and motorized vehicle activity
also impacted the prairie sites (Carr 1993). Recognizing the widespread loss of
prairie habitat and the degraded condition of isolated prairies on the SHNF, US Forest
Service and Texas Parks and Wildlife Department personnel began a restoration
project in 2004. Restoration consisted of mechanical removal of woody vegetation
when necessary and initiation of a prescribed-fire regime specifically designed to
reduce the prevalence of woody vegetation. On 5 of the prairie sites, restoration
efforts included a limited reintroduction of herbaceous prairie species using sod
and seed from nearby prairies. Restoration was successful in changing vegetation
structure to more closely resemble historic prairie vegetation (Diamond and Smeins
1988). The eventual goal of restoration is for prescribed fire to become the only
management treatment required to maintain prairie habitat.
Recognizing the improvement in prairie vegetation, we initiated winter bird
surveys in 2008 to document the use of restored prairies by avian species, especially
wintering sparrows in the genus Ammodramus. It is important to document
restoration efforts on these prairies because the data will provide a basis for any
future management and research that may occur on these important remnants of
blackland prairies in eastern Texas. Our avian surveys were initiated in 2008, four
years after prairie restoration, and after woody vegetation had largely been removed
and herbaceous vegetation was well established on most prairies. Consequently,
pretreatment avian and vegetation data are lacking. This situation precluded any
formal study design or statistical evaluation of our results. However our survey results
are important because they document the overall colonization pattern of these
prairies by grassland sparrows following restoration.
Study Area and Methods
The study was conducted on the SHNF in southeastern Texas on prairies selected
for restoration located in Walker and Montgomery counties. The prairies were small
(0.4–10.0 ha) and embedded within a forested landscape dominated by mixed Pinus
sp. (pine) and hardwood forest on the uplands, and bottomland hardwood forests
along major drainages. The prairies are restricted to heavy clay vertisols of the
Harris and Houston Black Series (Carr 1993, McClintock et al. 1972, 1979). Both
series are components of the Miocene Fleming Formation consisting of calcareous
marine sediments with high clay content (McClintock et al. 1972, 1979).
The isolated prairies of southeastern Texas have received virtually no ecological
or floristic attention (Brown et al. 2002), but the limited information available
suggests that they are transitional between the extensive blackland prairie to the
northwest and the coastal prairie to the south (Brown et al. 2002; Diamond and
Smeins 1984, 1988; MacRoberts and MacRoberts 2004; Nesom and Brown 1998;
Smeins and Diamond 1983). These prairies also have floristic affinities with isolated
prairies throughout the WGCP and eastward into Mississippi and Alabama
(MacRoberts and MacRoberts 2004). The calcareous soils underlying these prairies
support numerous species absent from the surrounding forested habitats, including
many herbaceous plants (Carr 1993) and gastropods (Hubricht 1985).
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Prairies of the SHNF have been degraded over the last century by agriculture,
silviculture, fire suppression, grazing, off-road vehicle use, and other causes. Agricultural
impacts ceased with the establishment of the national forest in the 1930s. In
recent years, silvicultural impacts, grazing, and off-road vehicle use in SHNF have
essentially eliminated sites that retain native prairie characteristics (Carr 1993).
Prescribed fire was widespread on the SHNF prior to restoration efforts, but it was
used primarily as a forest management tool; effects on prairie sites were incidental.
Thus, the effectiveness of prescribed fires on these prairies was limited by the season,
intensity, and differences in fuel characteristics between forest stands and the
prairie habitats within the burn areas.
Prescribed burning of areas that include the study prairies has been a regular
component of management on the SHNF for decades, as has occasional removal of
woody vegetation from the prairies using chainsaws. A more intensive management
protocol was initiated in 2004 with the specific objective of re storing the degraded
prairies. Restoration initially consisted of woody vegetation removal using mulching
machines, chainsaws, and mowing, as required to eliminate encroachment by
woody species. Mulched material was left in place, and intact woody material was
either burned, removed, or left in place depending on the amount present. Limited
reintroduction of herbaceous prairie species was attempted using seed harvested in
nearby areas (4 sites) and transplanting of sod (1 site). This effort was independent
of our avian surveys, and no data are available on the details of this effort. Following
the initial removal of woody vegetation, prescribed fire was applied when fuel
conditions were suitable and management resources were available.
Little information was available on the floristics and vegetation structure of the
prairies prior to initiation of restoration (Carr 1993; E. Keith, Raven Ecological
Services, Huntsville, TX, pers. comm.). We collected limited additional data on
selected prairies (% herbaceous cover, % woody cover) coincident with our avian
surveys in 2010 and 2011. Differences in data collection methods and the paucity
of pre-treatment data precluded analysis of these data.
We conducted winter avian surveys once per year between 19 January and 29
March from 2008 to 2011. In 2008, we surveyed only 5 prairies. We surveyed 16
prairies in 2009, and 23 in 2010 and 2011 as we continued to identify more prairie
sites and our survey resources increased. Two to nine observers conducted the
surveys depending on prairie size and year. Individual observers were spaced approximately
3 m apart and walked slowly through the prairies in a line (Bechtoldt
and Stouffer 2005). Width of prairie and number of observers frequently required
more than one pass to cover the entire prairie. We recorded all birds detected, and
birds that could not be identified when initially flushed—primarily Ammodramus
sparrows—were flushed repeatedly until identified or lost. Observers surveyed entire
prairies in this manner, and minimized double counting by carefully observing
the location where flushed birds landed. We were confident that double counting
was avoided because individual prairies were small and the grassland bird species
were present at relatively low abundance.
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Results
We initiated prairie restoration efforts in 2004 and intensified our efforts in 2007.
By 2008, we included a total of 23 prairies in restoration and survey efforts. Table 1
lists the prairies and their initial condition, based on visual assessment, prior to
the initiation of intensified management. Table 2 documents the history of woody
plant removal treatments and prescribed fire on the 23 prairies from 2004 to 2011.
Multiple mechanical treatments were frequently necessary to reduce woody vegetation
to levels compatible with development of prairie vegetation structure, i.e., the
development of dense herbaceous vegetation. Mechanical treatments are currently
being phased out. We could not measure pre-restoration woody vegetation because
restoration was well underway prior to initiation of the avian surveys. However, 1–3
mechanical treatments appear to have been sufficient to eliminate woody vegetation,
or at least reduce it to a level that could be effectively managed with fire.
Initial conditions on the prairies were highly variable. Most had moderate
(50–75%) to heavy (75–100%) canopy cover by woody vegetation, primarily Pinus
taeda L. (Loblolly Pine), Juniperus virginiana L. (Eastern Redcedar), Crataegus
spp. (hawthorns), Quercus spp. (oaks), Sideroxylon lanuginosum Michaux (Gum
Bumelia), Celtis laevigata Willdenow (Sugarberry), Ilex vomitoria Sol (Yaupon),
and Cornus drummondii von Meyer (Roughleaf Dogwood). Numerous additional
Table 1. Prairie condition (percent woody encroachment) prior to initiation of restoration activities.
Prairie designations are US Forest Service compartment and stand numbers and east–west or north–
south portions of stands.
% woody
Prairie encroachment Comments
2-1 E 58 >15-m pine encroachment
2-1 W 58 >15-m pine, w/ hardwood, and brush encroachment
2-2 E 1 Minimal encroachment
2-2 W 1 Minimal encroachment
2-9 35 3–5-m brush on periphery, center portion open
4-7 E 10 Minimal encroachment
4-7 W 10 Minimal encroachment
5-8 66 >15-m pines and brush on eastern portion and periphery
23-8 43 12-m pines and brush on western portion
33-8 78 10-m pines and brush on eastern 2/3 of site
58-14 ? 12-m pines in central portion and scattered Juniperus
60-10 23 >15-m scattered pines and 1–2-m brush
60-12 32 >15-m pines and 2-m brush on periphery
60-20 34 2–5-m pines and brush on periphery
60-21 38 2–4-m brush on periphery w/ minimal herbaceous vegetation
60-22 61 2–5-m brush on western side and periphery
60-23 40 2–4-m brush mostly on eastern portion and periphery
60-38 N 44 >15-m pines and 4–7-m brush throughout
60-38 S 44 Minimal encroachment
61-18 62 >15-m pines and 2–5-m brush on northern portion
62-10 33 >15-m pines and ? brush
62-13 99 4–5-m woody encroachment, minimal herbaceous vegetation
63-18 99 >15-m pine, 10-m Juniperus, and 5-m brush, minimal herbaceous vegetation
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species were present as minor components. Due to the dense shade created by the
woody plant canopy, herbaceous species cover was minimal. Portions of several
prairies were still relatively free of woody vegetation and supported a diverse herbaceous
flora based on visual assessments. However, based on the extent of vertisol
soils that presumably once supported prairie vegetation, we characterized all prairies
as being encroached upon by woody vegetation, at least around the margins.
The abundance of woody vegetation rapidly declined on encroached sites when
we initiated mechanical treatments (mulching, mowing, and chainsaw felling). Following
the removal of woody vegetation, herbaceous vegetation developed rapidly
on all sites except limited areas characterized by the most challenging edaphic
conditions including areas of active erosion and poor soils. Stand 21, Compartment
60 is one of the sites where we observed a rapid response by herbaceous species
following woody plant removal. Figure 1 depicts the site’s condition prior to restoration
in 2007; Figure 2 depicts the same site in 2011 following 2 mechanical
treatments and 2 prescribed fires.
Numerous plant species characteristic of these isolated prairies (Brown et
al. 2002, Carr 1993, MacRoberts and MacRoberts 2004) are currently present
post-restoration including Schizachyrium scoparium (Michaux) Nash (Little
Table 2. Area of 23 prairies on the Sam Houston National Forest and management activities carried
out by year, 2004–2011. Prairie = US Forest Service compartment and stand number, C = chainsaw
felling of woody vegetation, P = prescribed burn, Mu = mechanical removal of woody vegetation using
a mulching machine, and Mo = mowed.
Management activities by year
Prairie Area (ha) 2004 2005 2006 2007 2008 2009 2010 2011
2-1 E 7.3 C, P P P P P
2-1 W 3.5 C, P P P P P
2-2 E 3.6 P C, P P
2-2 W 4.7 P C, P
2-9 1.0 P P
4-7 E 2.3 P
4-7 W 3.0 P
5-8 2.8 C, P P P
23-8 1.5 Mu, P C
33-8 2.0
58-14 1.3
60-10 10.0 C, P P Mu, P P Mo
60-12 2.6 C, P P Mu P Mo
60-20 1.0 P Mu P Mo
60-21 1.9 Mu, P P Mo
60-22 0.4 Mu P
60-23 0.7 Mu Mo, P
60-38 N 1.0 Mu
60-38 S 1.6 Mu
61-18 1.9 Mu P
62-10 3.1 C, P P P Mo Mo
62-13 1.5 P P Mu
63-18 3.1 Mu, P C P
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Figure 2. Prairie in Compartment 60, Stand 21 on the Sam Houston National Forest, TX,
after restoration (2011).
Figure 1. Prairie in Compartment 60, Stand 21 on the Sam Houston National Forest, TX,
prior to restoration (2007).
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Bluestem), Andropogon gerardii Vitman (Big Bluestem), Bouteloua rigidiseta
(Steudl) Hitchcock (Texas Grama), Eustoma grandiflorum (Rafinesque) Shinners
(Prairie Gentian), Carex microdonta Torrey & Hooker (Littletooth Sedge),
Polytaenia nuttallii de Candolle (Prairie Parsley), Arnoglossum plantagineum
Rafinesque (Prairie Plantain), and Echinacea purpurea (L.) Moench (Purple
Coneflower). The presence of these species indicates that a significant portion of
the flora survived the period of fire suppression and grazing as remnant communities,
isolated plants within the encroached habitats, or in the seed bank, though
some may have been established through transfer of soil or seed from nearby
prairie sites as part of the restoration effort, or by natural dispersal. Non-native
species are relatively uncommon. However, Bothriochloa ischaemum (L.) Keng
(King Ranch Bluestem) is a pernicious invader present on most of the prairies we
surveyed, and abundant on several of them. Specific data are not available; however
casual observations indicate that King Ranch Bluestem has increased with
disturbance associated with restoration, and forest service personnel are initiating
control measures.
We detected a total of 1626 birds of 31 species on 23 prairies. These included
a suite of species characteristic of forest habitats. We frequently detected an additional
4 species—Spizella passerine Bechstein (Chipping Sparrow), Spizella
pusilla Wilson (Field Sparrow), Melospiza lincolnii Audubon (Lincoln’s Sparrow),
and Passerculus sandwichensis Gmelin (Savannah Sparrow)—characteristic of
grassland and edge habitats. These species tended to occur in fairly large flocks, and
their numbers varied substantially among prairies and years. Forest birds and those
that inhabit grassland and edge habitats accounted for 1215 (74.7%) of the total detections.
These species did not exhibit any consistent numerical trend across years,
likely due to their lack of strict dependence on improving prairie habitat, and the
highly variable data for the 4 species that often occurred in large flocks. Our surveys
failed to detect any members of a suite of several species that we consider typical
of grassland habitats in the region, including Circus cyaneus L. (Northern Harrier),
Eremophilus alpestris L. (Horned Lark), Anthus spragueii Audubon (Sprague’s
Pipit), and Cistothorus platensis Latham (Sedge Wren). In addition, we detected
Sturnella magna L. (Eastern Meadowlark) only once.
Three species of sparrows in the genus Ammodramus accounted for 411 of
the total detections (25.3%), of which 283 were identified to species. Ammodramus
henslowii Audubon (Henslow’s Sparrow) was the predominant species (214
individuals; 75.6%), followed by A. lecontii Audubon (Le Conte’s Sparrow; 67
individuals; 23.7%), and A. savannarum Gmelin (Grasshopper Sparrow; 2 individuals;
0.7%). Unidentified Ammodramus spp. totaled 128 individuals. Table 3
presents data for Ammodramus sparrows stratified by groups of prairies surveyed
for 4 (n = 5) and 3 (n = 11) years. The total number of individuals of Ammodramus
sparrows increased substantially across years in concert with the overall reduction
in woody vegetation and an increase in herbaceous vegetation during those same
years. Increases were substantial: an order of magnitude for the prairies surveyed
for 4 years, and a 27% increase for prairies surveyed for 3 years.
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The number of individuals of Ammodramus sparrows detected on specific prairies
across years was informative. At least 4 prairies (60-21, 60-38, 61-18, and
62-13) had very severe encroachment by woody vegetation prior to mechanical
treatments (Table 1). Woody vegetation was 3–5 m in height with an essentially
closed canopy, producing dense shade that had almost completely eliminated herbaceous
vegetation. Although bird surveys were not conducted prior to mechanical
removal of woody vegetation, the habitat was unsuitable for Ammodramus sparrows
due to the abundance of remaining woody vegetation and the paucity of herbaceous
vegetation in the moderately and heavily encroached prairies. Presumably, they
were absent or present in very low numbers. However, 1–3 growing seasons after
removal of woody plants, extensive grass cover was established, and the numbers
of Ammodramus sparrows began to increase substantially (Table 3).
Prescribed fires and unauthorized grazing also had an impact on use by Ammodramus
sparrows. Prairie 2-2 (20.9 ha) had limited woody encroachment, which
was removed by chainsaw in 2007. Prairie structure remained intact during the
2008 survey, and we detected 9 Ammodramus sparrows. In 2009, prescribed burning
was conducted prior to the avian survey, and we detected only 1 Henslow’s
Sparrow in a small patch of residual grass on the periphery of the prairie. In 2010,
cattle had grazed the site, resulting in a reduction of vegetation height to <15 cm,
and observers detected no Ammodramus sparrows. In 2011, herbaceous cover had
reestablished in the absence of burning and grazing, and we detected 30 Ammodramus
sparrows. Prairie 2-9, a small 1-ha site, was grazed in 2010, and observers
detected no Ammodramus sparrows. In the absence of grazing, we detected 2 Ammodramus
sparrows in 2009 and 1 in 2011.
Discussion
Although the lack of pre-treatment data and divergent sampling techniques precluded
statistical analysis of vegetation, several tentative conclusions are evident.
Following management, prairie sites that were heavily encroached by woody vegetation
were rapidly converted to communities dominated by herbaceous species
with a minimal or non-existent woody component. More importantly, many herbaceous
species present in historic and surviving remnants of blackland prairies and
in remnant patches within the current sites at the beginning of restoration activities
are now present on the restored sites. It is important to conduct detailed surveys to
document the current floristic makeup of these prairies.
Ongoing management will be required to maintain current progress and continue
the restoration of these prairies. In the absence of ecologically significant wildfire,
Table 3. Number of Ammodramus sparrows detected on 5 prairies surveyed for 4 years and 11 prairies
surveyed for 3 years, Sam Houston National Forest, TX (2007–2011).
# prairies 2008 2009 2010 2011
5 9 17 52 96
11 - 61 68 83
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prescribed fire will be necessary to prevent encroachment of woody vegetation.
Anecdotal observations of the current conditions suggest that prescribed fire will be
sufficient to maintain restored conditions once they are achieved. Some remaining
woody vegetation will require additional mechanical control and a few additional
prairie sites remain that are suitable for future restoration.
Due to the increased abundance of herbaceous vegetation and the fuel they
produce, prescribed fires remove all, or nearly all, woody vegetation and debris.
Future prescribed burns later in the growing season are under consideration both
to control invasive King Ranch Bluestem and to better match the presumed natural
fire regime. Erosional features >1 m deep are present at some sites. In the absence
of grazing, these washouts are becoming vegetated and the soil stabilized. If this
trend continues, specific measures to control erosion will not be required. However,
a number of plant species are dependent on areas of bare soil associated with these
erosional features (J. Singhurst, Texas Parks and Wildlife Department, Austin, TX,
pers. comm.) suggesting that some of these areas should be maintained.
Grazing by domestic stock is officially prohibited on these prairie sites; however,
unauthorized grazing still occurs, occasionally resulting in reduction of the
grass height to approximately 10 cm. These heavily grazed sites do not provide
suitable habitat for the Ammodramus sparrows. Grazing also has the potential to
reactivate erosion and introduce additional non-native species. Carr (1993) suggested
that stabilization of eroded portions of these prairies was unlikely as long
as grazing continues, strengthening the case for setting the elimination of grazing
as a management goal. Additionally, soil disturbance by feral hogs and off-road
vehicles occurs intermittently. Management efforts should be made to minimize
these and any other sources of soil disturbance.
Barring the return of fire-suppression, the threat from exotic invasive plant
species is undoubtedly the major threat to the continued existence of these prairie
communities. King Ranch Bluestem, a native of central Asia, is rapidly spreading
in the region (Gabbard and Fowler 2007). It is currently present in most of the
SHNF prairies and has the potential to drastically change the vegetation structure
with potentially serious impacts on floristics, grassland bird communities, and
other taxonomic groups. Some success in the control of King Ranch Bluestem
through the use of hot, growing-season fires, especially immediately prior to seed
dispersal, has been reported (Ruckman 2009, Simmons et al. 2008, but see Davis
2011). Prairie vegetation in the SHNF should be closely monitored to ascertain the
distribution and amount of King Ranch Bluestem and determine if control measures
are warranted.
The abundance of wintering grassland sparrows, primarily Henslow’s Sparrow,
is notable. Henslow’s Sparrow is of significant conservation concern
(Burhans 2002), and little is known concerning its wintering ecology. Several
studies have detailed the relationship of wintering Henslow’s Sparrows with fire
(Carrie et al. 2002, Johnson et al. 2009, Tucker and Robinson 2003), suggesting
that Henslow’s Sparrows preferentially use ephemeral habitats within 1–2 years
post-burn. This is consistent with the rapid arrival of wintering birds following
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2014 Vol. 13, Special Issue 5
prairie restoration in this study. The high density of Ammodramus sparrows is also
noteworthy. The 61.8 ha of prairie habitat surveyed in 2010 and 2011 supported
137 and 187 Ammodramus sparrows, respectively. Henslow’s Sparrows, were
most numerous, but substantial numbers of Le Conte’s Sparrows and an occasional
Grasshopper Sparrow were also present. Not all prairie habitat was suitable for
sparrows in any given year. To our knowledge, such a high density of wintering
Henslow’s Sparrows has not been previously reported on the WGCP. Christmas
Bird Count data for the WGCP only report low numbers, and our reported densities
are higher than those reported by Carrie et al. (2002) in Louisiana. The
density of Henslow’s Sparrows suggests that the prairies we studied may provide
quality wintering habitat for this species.
We presume that the extremely small size of these prairie inclusions is the reason
that our surveys failed to detect some species characteristic of regional prairie habitats.
Many of the grassland species that were absent at our survey sites have been
shown to exhibit aspects of area sensitivity (Herkert 1994, Johnson and Igl 2001).
However, most studies were of breeding birds, were conducted in landscapes more
heavily dominated by grasslands, and seldom included fragments as small as those
considered in this study. Consequently, results are not directly applicable, but do
suggest that area sensitivity is a factor.
Despite the regrettable lack of pretreatment data, we suggest that two very general
conclusions are indicated by the data available. First, effective restoration of
prairie vegetation is straightforward using mechanical treatments and prescribed
fire. Furthermore, restoration, including re-establishment of typical prairie plant
species, is rapid. Prairie conditions including low abundance or elimination of
woody vegetation, are established within 1–3 years after the start of restoration
efforts. Our study suggests that these restored conditions can be maintained
with prescribed fire as the only management tool, even on what had previously
been extremely fire-suppressed sites. Second, wintering sparrows in the genus
Ammodramus colonize the sites rapidly, following the first growing season postrestoration
in some cases. Within 1–2 years, high densities of Henslow’s Sparrows
can be present. These two general observations highlight both the feasibility and
importance of restoration and future management of these remnants of the blackland
prairie ecosystem on the Sam Houston National Forest.
The Blackland prairie community type of the WGCP is one of the most endangered
biotic communities of North America (MacRoberts and MacRoberts 2004,
Zollner et al. 2003). Very few examples remain that are both protected and in good
condition. The >60 ha represented by the isolated prairies on the SHNF are a significant
contribution to the preservation of this once widespread community (Carr
1993, MacRoberts and MacRoberts 2004). Land managers should make continued
management of these prairie remnants a high priority.
Acknowledgments
We thank J.A. Neal, M.H. MacRoberts, B.R. MacRoberts, J. Armacost, and an anonymous
reviewer for constructive comments on a draft of this manuscript.
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