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    Author(s): E.T. Nilsen; T.T. Lei; S.W. Semones
    Date: 2009
    Source: International Journal of Plant Sciences 170(6):735-747
    Publication Series: Scientific Journal (JRNL)
    PDF: Download Publication  (458.67 KB)


    We investigated whether dynamic photosynthesis of understory Quercus rubra L. (Fagaceae) seedlings can acclimate to the altered pattern of sunflecks in forest patches with Rhododendron maximum L. (Ericaceae), an understory evergreen shrub. Maximum photosynthesis (A) and total CO2 accumulated during lightflecks was greatest for 400-s lightflecks, intermediate for 150-s lightflecks, and lowest for 50- and 75-s lightflecks. For the 400-s lightflecks only, maximum A and total CO2 accumulated were significantly lower for seedlings in forest patches with shrubs present (SF) than for seedlings in forest patches without shrubs (F). These effects were found only when Awas calculated on a leaf-area basis because the specific leaf area of seedlings in F patches was 16% lower than it was for seedlings in SF patches. Photosynthesis reached 50% induction in 159 s for seedlings in F patches compared with 226 s for seedlings in SF patches. The faster induction of A for seedlings in F patches resulted in a significantly higher lightfleck use efficiency than for seedlings in SF patches. The inefficient use of lightflecks by Q. rubra seedlings in SF patches may be a primary mechanism by which Q. rubra seedlings are inhibited by subcanopy thickets of R. maximum.

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    Nilsen, E.T.; Lei, T.T.; Semones, S.W. 2009. Presence of understory shrubs constrains carbon gain in sunflecks by advance-regeneration seedlings: evidence from Quercus Rubra seedling grouwing in understory forest patches with or without evergreen shrubs present. International Journal of Plant Sciences 170(6):735-747.


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    dynamic photosynthesis, sunfleck responses, transient light, advance regeneration, deciduous forest, Quercus rubra, Rhododendron maximum

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