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Intra-Annual Variation in Soil C, N and Nutrients Pools after Prescribed Fire in a Mississippi Longleaf Pine (Pinus palustris Mill.) Plantation
Open AccessArticle

Physiological Mechanisms of Foliage Recovery After Spring or Fall Crown Scorch in Young Longleaf Pine (Pinus palustris Mill.)

1
USDA Forest Service, Southern Research Station, Pineville, LA 71360, USA
2
Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705, USA
3
USDA Forest Service, Southern Research Station, Athens, GA USA 30602, USA
4
School of Forestry, Louisiana Tech University, Ruston, LA 71272, USA
5
School of Environmental Citizenship, Unity College, Unity, ME 04988, USA
*
Author to whom correspondence should be addressed.
Forests 2020, 11(2), 208; https://doi.org/10.3390/f11020208
Received: 16 January 2020 / Revised: 4 February 2020 / Accepted: 5 February 2020 / Published: 12 February 2020
(This article belongs to the Special Issue Longleaf Pine)
We hypothesized that physiological and morphological responses to prescribed fire support the post-scorch foliage recovery and growth of young longleaf pine. Two studies conducted in central Louisiana identified three means of foliage regrowth after fire that included an increase in the gas exchange rate of surviving foliage for 3 to 4 months after fire. Saplings also exhibited crown developmental responses to repeated fire that reduced the risk of future crown scorch. Starch reserves were a source of carbon for post-scorch foliage regrowth when fire was applied in the early growing season. However, the annual dynamics of starch accumulation and mobilization restricted its effectiveness for foliage regrowth when fire was applied late in the growing season. As such, post-scorch foliage regrowth became increasingly dependent on photosynthesis as the growing season progressed. Additionally, the loss of foliage by fire late in the growing season interrupted annual starch dynamics and created a starch void between the time of late growing season fire and mid-summer of the next year. The occurrence of drought during both studies revealed barriers to foliage reestablishment and normal stem growth among large saplings. In study 1, spring water deficit at the time of May fire was associated with high crown scorch and poor foliage and stem growth among large saplings. We attribute this lag in stem growth to three factors: little surviving foliage mass, low fascicle gas exchange rates, and poor post-scorch foliage recovery. In study 2, May fire during a short window of favorable burning conditions in the tenth month of a 20-month drought also reduced stem growth among large saplings but this growth loss was not due to poor post-scorch foliage recovery. Application of this information to prescribed fire guidelines will benefit young longleaf pine responses to fire and advance efforts to restore longleaf pine ecosystems.
Keywords: crown architecture; drought; dry mass allocation; net photosynthesis; prescribed fire; starch dynamics; annual increment of stem growth; stomatal conductance; vapor pressure deficit crown architecture; drought; dry mass allocation; net photosynthesis; prescribed fire; starch dynamics; annual increment of stem growth; stomatal conductance; vapor pressure deficit
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MDPI and ACS Style

Sayer, M.A.S.; Tyree, M.C.; Kuehler, E.A.; Jackson, J.K.; Dillaway, D.N. Physiological Mechanisms of Foliage Recovery After Spring or Fall Crown Scorch in Young Longleaf Pine (Pinus palustris Mill.). Forests 2020, 11, 208.

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