Effects of stand age on tree biomass partitioning and allometric equations in Chinese fir ( Cunninghamia lanceolata ) pl
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ORIGINAL PAPER
Effects of stand age on tree biomass partitioning and allometric equations in Chinese fir (Cunninghamia lanceolata) plantations Wenhua Xiang1,2 · Linhua Li1,3 · Shuai Ouyang1,2 · Wenfa Xiao4 · Lixiong Zeng4 · Liang Chen1,2 · Pifeng Lei1,2 · Xiangwen Deng1,2 · Yelin Zeng2 · Jiangping Fang5 · David I. Forrester6 Received: 28 January 2020 / Revised: 30 August 2020 / Accepted: 4 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Although stand age affects biomass partitioning and allometric equations, the size of these effects and whether it is worth incorporating stand age into allometric equations, requires further attention. We sampled a total of 90 trees for 10 Chinese fir (Cunninghamia lanceolata) plantations at seven stand age classes to obtain the data of tree component biomass using destructive harvesting. A multilevel modeling approach was applied to examine how stand age effects differ among tree components and predictor variables (diameter at breast height, DBH and tree height, H). Age class-specific allometric equations and the best fitting generalized equation that included stand age as a complementary variable were developed for each tree component. Large differences in both the intercept and slope for different stand age classes indicated that stand age affected allometric models. Branch and leaves were more sensitive to the environment and were the tree components most affected by stand age. Age class-specific allometric equations fitted well (R2 > 0.65, p 30 years) Class 7 (> 30 years) Class 7 (> 30 years)
3119 2490 2175 2370 1958 1635 1905 1560 1590 1305
3.2 9.6 11.6 13.5 15.3 16.5 18.1 18.5 20.1 23.3
1.7 8.7 9.8 12.8 13.8 13.8 16.3 16.6 22.2 22.2
2.51 18.01 22.97 33.91 35.98 34.94 48.99 41.91 50.42 55.62
0.333 ± 0.058 0.280 ± 0.042 0.280 ± 0.042 0.318 ± 0.036 0.339 ± 0.054 0.309 ± 0.058 0.314 ± 0.057 0.329 ± 0.068 0.329 ± 0.068 0.329 ± 0.068
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tree base, at half H and at the lowest living branch of the felled trees were recorded. Tree stems were then cut at 1.3 m and at 1-m intervals thereafter up to the apex. The branches were stripped from each stem section. The stem sections and the branches with leaves were weighed in situ. The sum of the weights of all stem sections from a given tree was the total fresh stem mass. Based on the branch size, three to five random samples of branches with leaves were collected for each stem section to estimate the fraction of branch and leaf biomass. Leaves were removed from the sampled branches. The fresh mass of the leaves and branches was measured separately to calculate the ratio of leaf to branch mass and to determine the total fresh biomass of foliage and branches. One disk per stem section and subsamples of leaves and branches were collected, put into cloth bags and transported to the laboratory. Root biomass was determined using a manual excavation method. The stump was excavated before excavating the rest of the roots by tracing them back to their root tips, as far as
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