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Abstract Detail



Ecological Section

Huebner, Cynthia [1], Minocha, Rakesh [2], Long, Stephanie [2].

Comparison of plant growth and stress response of Microstegium vimineum, Ailanthus altissima, Alliaria petiolata, and Quercus rubra across a light gradient.

Oak regeneration in Eastern deciduous forests is dependent on increase in light to the forest understory, which is often accomplished by harvesting and fire. These disturbances can promote invasion by exotic plants, including Microstegium vimineum (MV), a shade-tolerant C4 grass, Ailanthus altissima (AA), a shade intolerant tree, and Alliaria petiolata (AP), a shade intolerant herb which invades in early spring. We grew 10 replicates of three invasive plant species (MV, AA, and AP), and Quercus rubra (QR, a native oak species) in growth chambers under six different light levels which represented light conditions of forests under different management regimes. The lowest light levels (70 and 120 umolm-2s-1) represented closed canopy forests, while the intermediate levels (180 and 215 umolm-2s-1) represented thinned forests, and the highest light levels (285-415 umolm-2s-1) represented shelterwood cuts with 30-60% residual trees. All plants were grown for 35 days. Height and leaf number were determined for each plant. Biochemical indicators of stress were measured. These included chlorophyll a/b, the polyamines putrescine, spermidine, and spermine, and the amino acid proline. All three invasive plants showed significantly more growth at light levels above 120. QR growth showed less of a pattern, with no significant difference among the 70, 120, 285, and 415 light levels and the tallest shoots at 180 and shortest at 215, suggesting seed source effects. AA, MV, and QR showed greater chlorophyll a/b at 415 compared to all other light levels. AP chlorophyll a/b was lower at the 70 and 120 light levels compared to all other light levels. AA, MV, and AP showed an increase in putrescine content with increasing light levels but no corresponding increase in spermine. This and our growth data suggest that these putrescine levels are indicative of growth and not stress. The largest difference in putrescine content occurred between light level 285 and 415 for all three invasive plants. QR showed lower levels of putrescine at light levels of 70 and 120 while no differences were observed at 180, 285, and 415. There is some indication of possible pot effects on AP, which experienced higher proline levels (water stress indicator) at light above 285. Thus, these invasive species perform best at light above 415, while QR appears to perform equally well at light level 285 (possibly even 180) and above. Our findings support managing forests with less canopy removal, which will help prevent invasion but still promote oak regeneration.

Broader Impacts:


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1 - Northern Research Station, United States Forest Service, United States Department of Agriculture, 180 Canfield St., Morgantown, WV, 26505, USA
2 - Northern Research Station, United States Forest Service, United States Department of Agriculture, 271 Mast Road, Durham, NH, 03824, USA

Keywords:
plant stress
invasive plants
oak regeneration.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Number: PEC014
Abstract ID:436
Candidate for Awards:None


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