Drought-deciduous behavior reduces nutrient losses from temperate deciduous trees under severe drought |
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Authors: | Renée Marchin Hainian Zeng William Hoffmann |
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Institution: | (1) Department of Plant Biology, North Carolina State University, Campus Box 7612, Raleigh, NC 27695-7612, USA; |
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Abstract: | Nutrient resorption from senescing leaves is an important mechanism of nutrient conservation in temperate deciduous forests.
Resorption, however, may be curtailed by climatic events that cause rapid leaf death, such as severe drought, which has been
projected to double by the year 2100 in the eastern United States. During a record drought in the southeastern US, we studied
18 common temperate winter-deciduous trees and shrubs to understand how extreme drought affects nutrient resorption of the
macronutrients N, P, K, and Ca. Four species exhibited drought-induced leaf senescence and maintained higher leaf water potentials
than the remaining 14 species (here called drought-evergreen species). This strategy prevented extensive leaf desiccation
during the drought and successfully averted large nutrient losses caused by leaf desiccation. These four drought-deciduous
species were also able to resorb N, P, and K from drought-senesced leaves, whereas drought-evergreen species did not resorb
any nutrients from leaves lost to desiccation during the drought. For Oxydendrum arboreum, the species most severely affected by the drought, our results indicate that trees lost 50% more N and P due to desiccation
than would have been lost from fall senescence alone. For all drought-deciduous species, resorption of N and P in fall-senesced
leaves was highly proficient, whereas resorption was incomplete for drought-evergreen species. The lower seasonal nutrient
losses of drought-deciduous species may give them a competitive advantage over drought-evergreen species in the years following
the drought, thereby impacting species composition in temperate deciduous forests in the future. |
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