Age-related modulation of the nitrogen resorption efficiency response to growth requirements and soil nitrogen availability in a temperate pine plantation
Sun, Zhenzhong (Beijing da xue. College of Urban and Environmental Sciences. Department of Ecology)
Liu, Lingli (Zhongguo ke xue yuan. Institute of Botany)
Peng, Shushi (Beijing da xue. College of Urban and Environmental Sciences. Department of Ecology)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Zeng, Hui (Peking University Shenzhen Graduate School)
Piao, Shilong (Beijing da xue. College of Urban and Environmental Sciences. Department of Ecology)

Data:	2016
Resum:	Nitrogen (N) resorption is a key strategy for conserving N in forests, and is often affected by soil nutrient condition and N sink strength within the plant. However, our understanding of the age-related pattern of N resorption and how increasing N deposition will affect this pattern is limited. Here, we investigated N resorption along a chronosequence of stands ranging in age from 2 to 100 years old, and conducted a 4-year exogenous N input experiment in stands at age class 11, 20, and 45 in a Larix Principis-rupprechtii plantation in north China. We found a logarithmic increase in leaf N resorption efficiency (NRE) and green leaf N concentration, and a logarithmic decrease in senesced-leaf N concentration along the stand-age chronosequence. Leaf NRE was negatively correlated with plant-available N concentration. Stand-level N resorption was positively correlated with the annual N requirement for tree growth. N resorption contributed to 45, 62, and 68% of the annual N supply in the 11-, 20-, and 45-year-old stands, respectively. Our exogenous N input experiment showed that leaf NRE in the 11- and 20-year-old stands decreased 17 and 12% following a 50-kg N ha¯¹ y¯¹ input. However, leaf NRE was not affected in the 45-year-old stand. The increases in leaf NRE and the contribution of N resorption to annual N supply along stand ages suggested that, with stand development, tree growth depends more on N resorption to supply its N need. Furthermore, the leaf NRE of mature stand was not decreased under exogenous N input, suggesting that mature stands can be stronger sinks for N deposition than young stands due to their higher capacity to retain the deposited N within plants via internal cycle. Ignoring age-related N use strategies can lead to a bias in N cycle models when evaluating forest net primary production under increasing global N deposition.
Ajuts:	European Commission 610028
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Nitrogen resorption ; Green leaves ; Senesced leaves ; Nitrogen requirement ; Nitrogen deposition ; Stand age ; Plant-available nitrogen ; Annual stand biomass production
Publicat a:	Ecosystems, Vol. 19, Issue 4 (June 2016) , p. 698-709, ISSN 1435-0629

DOI: 10.1007/s10021-016-9962-5

Post-print 34 p, 801.6 KB

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