Growth, Biomass Production and Root Development of Chinese fir in Relation to Initial Planting Density

Abstract

Chinese fir (Cunninghamia lanceolata (Lamb) Hook) is a commercially valuable timber species that is widely planted in southern China and accounts for 6.1% of the global plantation forests. However, appropriate planting density that ensures high plantation productivity is largely unexplored in this species. The aim of the study was to examine tree growth, biomass production, and its allocation among different organs in relation to initial planting density, and to examine whether planting density has an impact on root development. Mortality, diameter at breast height and tree-height of all trees were determined and measured in wider (2.36 × 2.36 m), intermediate (1.83 × 1.83 m) and narrow (1.44 × 1.44 m) spacing with stand density of 1450 trees ha−1, 2460 trees ha−1 and 3950 trees ha−1, respectively. In each stand, three plots of 20 × 20 m at a distance of 500 m were delineated as the sampling unit. Biomass was determined by destructive sampling of trees in each stand and developing allometric equations. Root morphological traits and their spatial distribution were also determined by carefully excavating the root systems. The results showed an increase in diameter of trees with decreasing stand density while tree height was independent of stand density. Biomass production of individual trees was significantly (p < 0.05) less in high-density stand (32.35 ± 2.98 kg tree−1) compared to low-density stand (44.72 ± 4.96 kg tree−1) and intermediate-density stand (61.35 ± 4.78 kg tree−1) while stand biomass production differed significantly in the order of intermediate (67.63 ± 5.14 t ha−1) > high (57.08 ± 3.13 t ha−1) > low (27.39 ± 3.42 t ha−1) stand density. Both average root length and root volume were significantly (p < 0.05) lower in the high-density stand than stands with low and intermediate density. Analysis of spatial distribution of root systems revealed no overlap between roots of neighboring trees in the competition zone in low-density stand, a subtle overlap in the intermediate density stand and larger overlap in the high-density stand. It can be concluded that better growth and biomass production in intermediate density stand could be explained by better root structural development coupled with minimal competition with understory vegetation and between trees; thus intermediate stand density can be optimal for sustaining long-term productivity and may reduce the management cost in the early phase of the plantation.

Intercropping of Peanut–Tea Enhances Soil Enzymatic Activity and Soil Nutrient Status at Different Soil Profiles in Subtropical Southern China

“…The enhancement and maintenance of soil productivity and sustainability through the long-term use of different silvicultural practices, such as varying planting density and spacing, introducing native and exotic beneficial species, agroforestry and intercropping, has been widely used worldwide [ 1 , 2 , 3 , 4 , 5 , 6 ]. Intercropping can enhance soil quality by incorporating a significant amount of topsoil and subsoil organic matter and releasing and recycling nutrients [ 7 , 8 , 9 ].…”

Perspectives of plantation forests in the sustainable forest development of China

“…Although natural forests provide higher environmental services than plantations (Yamagawa et al 2010, Xu et al 2012, the latter also play a vital role by provisioning clean air and water protection. Plantation forests can provide most services such as woody and non-woody products, biodiversity, aesthetics, carbon sequestration, climate control, and soil erosion control (Sasaki & Yoshimoto 2010, Ruiz-Jaen & Potvin 2011, Farooq et al 2019a, 2019b, 2019c. Plantations grow much faster than the natural forests, having specific value in terms of timber supply, fast forest spread, and ecosystem conservation (Chinnaraj & Malimuthu 2011, Farooq et al 2018, 2019a, 2019b.…”

“…Plantation forests can provide most services such as woody and non-woody products, biodiversity, aesthetics, carbon sequestration, climate control, and soil erosion control (Sasaki & Yoshimoto 2010, Ruiz-Jaen & Potvin 2011, Farooq et al 2019a, 2019b, 2019c. Plantations grow much faster than the natural forests, having specific value in terms of timber supply, fast forest spread, and ecosystem conservation (Chinnaraj & Malimuthu 2011, Farooq et al 2018, 2019a, 2019b. Hence, plantations have become a crucial part of China's afforestation efforts to tackle climate change and air pollution (Zeng et al 2015).…”

Diversity, biomass, and carbon stock of understorey plants in the rubber agroforestry and rubber monoculture systems in Central Tapanuli District, North Sumatra, Indonesia

“…At plantation stand level, biomass production increases with increasing stand density due to the biomass of the extra trees compensating for the decrease in the size of individuals (Dickens et al 2004). The result of study Farooq et al (2019) that larger biomass of needles, bark, stem, stump root, and coarse roots was recorded for trees in intermediate-density stand than either the low or highdensity stand. The above-ground biomass was the largest in intermediate-density stand followed by the low-density stand and the smallest being in high-density stand.…”