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Study Number: |
1003 | ||||
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Project Title: |
Seedling recruitment in artificial gaps. | ||||
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Investigator(s): |
Brian Beckage E-Mail | Tel. 919.477.8542 |
Beckage website James Clark E-Mail | Tel. 919.660.7402 | Biographical Sketch | The Clark Lab |
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| Affiliated Institution(s): | Duke University | ||||
| Address: |
Duke University
Department of Biology Durham, North Carolina 27708 USA |
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| Study Type: | Terrestrial | ||||
| Project Type: | Coweeta Core Research | ||||
| Study Period: |
06/1993 - 06/2000 |
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| Status/Notes: |
Type 1 Project complete, no further edits. |
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| Funding Sources: |
National Science Foundation, DEB-9632854 (Text Version) and DEB-0218001 (Text Version) to Coweeta LTER. |
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| Abstract: |
We examined the role of both
intermediate-sized gaps and a dense shrub layer on subsequent tree
seedling recruitment in a southern Appalachian deciduous forest. We
monitored the density of tree seedlings in twelve artificial gaps and
adjacent canopy controls under two contrasting understory conditions.
Half of the experimental gaps were dominated by the dense,
shade-producing shrub,
Rhododendron maximum, while the remaining gaps
were relatively open.
Canopy gaps 20 m in diameter were created by
girdling canopy trees, leaving standing dead trees with minimal
disturbance to the
understory. Density of first-year and
first-year
seedlings was monitored in transects extending from adjacent undisturbed
forest through the experimental gaps. Resources
for students about terms used in this study:Rhododendron maximum - Source: USDA Plants Database Southern Appalachian Deciduous Forests - Source: Coweeta LTER Gap studies - Coweeta LTER |
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| Location(s), Described: | Upper (Watershed 27) and Lower (Watershed 18) Gap Plots | ||||
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Location(s): Elevation Decimal Degrees UTM, Zone 17, NAD83 |
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Transect ln1 ln2 ln3 lr1 lr2 lr3 un1 un2 un3 ur1 ur2 ur3 |
Latitude -83.43 -83.43 -83.43 -83.43 -83.43 -83.43 -83.46 -83.46 -83.46 -83.46 -83.46 -83.461072 |
Longitude 35.050926 35.051346 35.050583 35.051512 35.051600 35.051837 35.038191 35.038569 35.038711 35.038149 35.038408 35.037922 |
UTM X 278209.53 278239.28 278229.96 278223.71 278241 278172.87 275471.84 275482.93 275460.06 275500.65 75519.09 275501.75 |
UTM Y 3881394.70 3881441.50 3881357.50 3881459.00 3881468.50 3881497.50 3880049.00 3880089.20 3880105.20 3880041.20 3880071.00 3880017.20 |
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| Location(s), Download GPS: | ArcView Shape Files (.shp): UTM, NAD83, Zone 17 | Lat/Lon | ||||
| Location(s), Online Maps: |
 USGS
Topographic Maps of research sites for this project(Printable for fieldwork)
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| Methods/Experimental Design: |
Our clusters of experimental
gaps were located in two mixed oak stands that bracket the elevation
range of this community, hereafter referred to as low elevation (850
m) and high elevation (1100 m) sites. Sites had a northeast aspect and
slopes ranged from 30% to 50% (high elevation) and from 45% to 70% (low
elevation). At both sites, we established six plots (12 plots total),
each corresponding to a single experimental gap. Three of the six plots
at each elevation had a dense
Rhododendron maximum
understory, while three plots
lacked Rhododendron maximum. Rhododendron maximum has a patchy distribution at these sites,
permitting us to locate experimental gaps (with and without Rhododendron
maximum) in close proximity, thus allowing for consistent
overstory
composition, slope, soils, and
microclimate.
Locations for experimental gaps were selected in 1991, and canopy trees were marked for girdling to produce gaps of approximately 300 m2 (expanded gap definition, Runkle 1981). Up to five trees from a variety of species were girdled to create each gap. A transect, comprised of 40 contiguous 1 m2 quadrats, was established across each planned gap. Transects were generally oriented in a north-south direction. Transects included 20 central quadrats exposed to gap conditions and 20 outer quadrats subtended by the surrounding canopy. There were a few exceptions to this layout, due to topographic considerations or patchiness of the Rhododendron maximum. In these cases, transects deviated from a north-south orientation or were interrupted to maintain consistent understory conditions (e.g., Rhododendron maximum or non Rhododendron maximum). Following collection of pretreatment data in 1993, we produced experimental canopy gaps by girdling trees in late summer of the same year. The herbicide Garlon was applied to trees that leafed out the following spring. Girdled trees remained standing for the duration of our study, although large branches began to fall in the 4th year. We censused tree seedlings along all transects annually in July or August from 1993 to 1997. We identified all seedlings and saplings less than 2 m tall to genus or species (for Acer rubrum, Liriodendron tulipifera, and Quercus prinus). Seedlings classified as Betula spp were likely Betula lenta, because Betula allegheniensis is restricted to the highest elevations at Coweeta. We were unable to confidently differentiate all seedlings of Quercus velutina, Quercus coccinea, and Quercus rubra, so these are grouped as Quercus rubra-type. |
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| Sampling Frequency: | Yearly | ||||
| Data Columns: |
Quadrant - Quadrant ID |
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| Publications: |
Beckage, Brian, J. S. Clark, B.
Clinton, and B. Haines. 2000.
A long-term study of tree seedling recruitment
in Southern Appalachian forests: the effects of canopy gaps and shrub understories.
Canadian Journal of Forest Research.
30: 1617-1631. |
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| Data Restrictions: | Users must adhere to the Coweeta LTER Data Policy. | ||||
| Metadata: | EML Format (XML Schema) | Information about EML | ||||
| Data Downloads: |
Microsoft® Excel (.xls) DBase (.dbf) |
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