Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (5): 458-470.

• Research Articles •

### Reuse of retranslocated nutrients in tissues of Chinese fir in plantations of different ages

LÜ Zhong-Cheng1,4,KANG Wen-Xing1,2,3,*(),HUANG Zhi-Hong1,2,3,ZHAO Zhong-Hui1,2,3,DENG Xiang-Wen1,2,3

1. 1. Central South University of Forestry and Technology, Changsha 410004, China
2. National Engineering Laboratory for Applied Technology of Forestry & Ecology in South China, Changsha 410004, China;
3. Huitong National Field Station for Scientific Observation and Research of Chinese Fir Plantation Ecosystem, Huitong, Hunan 418307, China
4. Hunan Police College, Changsha 410138, China
• Online:2019-05-20 Published:2019-10-28
• Contact: KANG Wen-Xing
• Supported by:
Supported by the National Forestry Public Welfare Industry Research Project(201104009);The Ministry of Science and Technology Public Welfare Research Project(2007-04-15);The National Field Science Observation and Research Station Project(20080615)

Abstract: Aims The purpose of this study is to investigate the reuse characteristics of nutrients (Nitrogen, Phosphorus, Potassium, Calcium, Magnesium) in Cunninghamia lanceolata with different ages, and therefore provide scientific support for better management of the high-yield plantations in China. Methods We estimated the nutrient retranslocation from dying branches and leaves according to nutrient concentration differences between living and dead, and the amount of dead branches and leaves in Chinese fir forests of different age classes in Hunan Huitong. Based on the difference in the nutrient concentrations of Chinese fir organs at the beginning and end of each age class, the nutrient transport amount from “biomass produced before the beginning of a given age class, which is still alive at the end of the age class” (referred as “biomass-still-alive” hereafter) was estimated for the age class. The nutrient utilization characteristics in forest production were comprehensively analyzed by combining the nutrients transferred from dying branches and leaves with those transferred from the biomass still alive and absorbed from the soil. Important findings The results showed that the annual biomass produced by the retranslocated nutrients of dying branches and leaves and their proportion in the total biomass were 217 kg·hm -2·a -1 and 3.52%, respectively, for forests 1-7 years old, and increased to 2 540 kg·hm -2·a -1and 17.50%, respectively, when forests reached 20-25 years old. The biomass produced by the retranslocated nutrients of dying branches and leaves and its proportion in the total biomass increased with the increase of forest age. The average annual biomass produced by the biomass-still-alive in stands of 12-16, 17-20 and 21-25 years old was 385, 561 and 450 kg·hm -2·a -1, accounting for 3.40%, 3.40% and 3.11% of the total biomass production, respectively. The nutrient retranslocation from the biomass-still-alive first increased and then decreased with the increase of forest age, and the proportion of the biomass produced by these nutrients to the total biomass showed a decreasing trend with the increase of forest age. The results show that the death of branches and leaves always results in reuse of retranslocated nutrients. On the other hand, the reuse of retranslocated nutrients from the biomass-still-alive occurs only after canopy closure. The mechanism of nutrient redistribution and storage, the growth pattern and the nutrient demand and utilization efficiency at different growth stages of Chinese fir jointly regulate and control the annual changes of nutrient retranslocation before branches and leaves die and the reuse of retranslocated nutrients from the biomass-still-alive.

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