Browsing by Subject "biomass allocation"

Now showing 1 - 4 of 4
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    The colonization of active sand dunes by rhizomatous plants through vegetative propagation and its role in vegetation restoration
    (2012-07) Liu, Bo; Liu, Zhimin; Wang, Lixin
    This study aims to elucidate vegetative propagation in Phragmites communis, and its role in colonizing active sand dunes. The experiment was conducted in the Horqin Sand Land in Inner Mongolia, northeastern China. Quadrats were established along twenty transects from the dune slack to the windward slope through the ecotone (a transitional zone between the dune slack and the windward slope of active sand dune). Biomass, biomass allocation and relative growth rate (RGR) of P. communis were quantified monthly from May to August in 2007. Our results showed that rhizomes extended towards the active sand dune at a rate of 523.5 ± 20.8 cm per year. The RGR of ramets and rhizomes increased along the gradient from the dune slack to the windward slope. The percentage of rhizome biomass in total biomass increased significantly along the same gradient. The results indicate that P. communis is able to adjust growth strategy according to the environmental conditions. The results also demonstrate that vegetative propagation of rhizomatous grasses significantly contributes to plant encroachment to active sand dunes and plays an important role in the vegetation restoration of dune fields.
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    Excessive Accumulation of Chinese Fir Litter Inhibits Its Own Seedling Emergence and Early Growth—A Greenhouse Perspective
    (MDPI, 2017-09-11) Liu, Bo; Daryanto, Stefani; Wang, Lixin; Li, Yanjuan; Liu, Qingqing; Zhao, Chong; Wang, Zhengning; Earth Science, School of Science
    Litter accumulation can strongly influence plants’ natural regeneration via both physical and chemical mechanisms, but the relative influence of each mechanism on seedling establishment remains to be elucidated. Chinese fir (Cunninghamia lanceolata) is one of the most important commercial plantations in southern China, but its natural regeneration is poor, possibly due to its thick leaf litter accumulation. We used natural and plastic litter to study the effects of Chinese fir litter on its own seedling emergence and early growth, as well as to assess whether the effect is physical or chemical in nature. Results showed that high litter amount (800 g·m−2) significantly reduced seedling emergence and the survival rate for both natural and plastic litter. Low litter amount (200 g·m−2) exerted a slightly positive effect on root mass, leaf mass, and total mass, while high litter amount significantly inhibited root mass, leaf mass, and total mass for both natural and plastic litter. Root-mass ratio was significantly lower, and leaf-mass ratio was significantly greater under high litter cover than under control for both natural and plastic litter. Although the root/shoot ratio decreased with increasing litter amount, such effect was only significant for high litter treatment for both natural and plastic litter. Seedling robustness (aboveground biomass divided by seedling height) decreased with increasing litter amount, with high litter treatment generating the least robust seedlings. Because plastic and natural litter did not differ in their effects on seedling emergence and growth, the litter layer’s short-term influence is primarily physical. These data indicated that as litter cover increased, the initial slightly positive effects on seedling emergence and early growth could shift to inhibitory effects. Furthermore, to penetrate the thick litter layer, Chinese fir seedlings allocated more resources towards stems and aboveground growth at the expense of their roots. This study provided experimental evidence of litter amount as a key ecological factor affecting seedling development and subsequent natural regeneration of Chinese fir.
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    Responses of Chinese fir and Schima superba seedlings to light gradients: Implications for the restoration of mixed broadleaf-conifer forests from Chinese fir monocultures
    (Elsevier, 2018-07) Liu, Bo; Liu, Qingqing; Daryanto, Stefani; Guo, Si; Huang, Zhijun; Wang, Zhengning; Wang, Lixin; Ma, Xiangqing; Earth Sciences, School of Science
    Although Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantations are widely grown for timber production in southern China, they have low biodiversity and provide limited ecosystem services. To address this problem, C. lanceolata are increasingly mixed with broadleaf Schima superba Gardn. & Champ. (Theaceae). The success of these mixed plantations relies on introducing each species in the appropriate sequence, which requires understanding how tree species respond to light variations. We therefore compared S. superba and C. lanceolata seedling light tolerance in shaded houses under five light gradients (5%, 15%, 40%, 60%, and 100% sunlight). Our findings showed that S. superba seedlings exhibited greater net height increment (ΔHt), net diameter growth (ΔDia), leaf area, root mass, stem mass, leaf mass, and total mass under low light conditions (15% sunlight). However, as sunlight increased, these growth variables became higher in C. lanceolata seedlings. With more sunlight, both species experienced a drop in height to diameter ratio (HDR), and specific leaf area (SLA), but an elevated root to shoot ratio. Additionally, under the same light levels, S. superba seedlings exhibited greater leaf area and root to shoot ratio than C. lanceolata seedlings. Our results suggested that S. superba might be more suitable for underplanting beneath a heavy canopy due to its shade-tolerant traits. In contrast, C. lanceolata was less shade-tolerant, having an optimum seedling growth under full sunlight. These findings suggest that underplanting S. superba seedlings in C. lanceolata monoculture plantation (i.e., underplanting regeneration approach) could be a better silvicultural alternative than simultaneously planting both seedlings.
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    Seedling emergence and early growth of Chinese fir under different light levels and seed positions: implications for natural regeneration
    (Canadian Science Publishing, 2018-09) Liu, Bo; Liu, Qingqing; Daryanto, Stefani; Ma, Xiangqing; Guo, Si; Wang, Lixin; Wang, Zhengning; Earth Sciences, School of Science
    Chinese fir, Cunninghamia lanceolata (Lamb.) Hook. (Taxodiaceae), is an evergreen conifer primarily distributed in southern China. This species exhibits very poor natural regeneration, possibly due to low light and a thick litter layer. To improve the understanding of the natural regeneration capacity of Chinese fir, in this study, we conducted a shade house experiment to determine the optimum light requirements and seed positions for seedling emergence and early growth. The experiment involved five light levels (100%, 60%, 40%, 15%, 5% of full sunlight) and four seed positions (1 cm beneath the soil surface without litter, on the soil surface without soil–seed contact, on the soil surface and covered with litter, and 1 cm beneath the soil surface and covered with litter). Seedling emergence was highest at 5%–15% sunlight, whereas seedling height, root length, root mass, stem mass, leaf mass, and total mass were highest at 60% sunlight. For each light level, seed position significantly affected emergence and growth. The above-litter position inhibited seedling emergence and survival, while the below-litter position favored seedling emergence and early growth, particularly under high light levels. Based on these results, to enhance natural regeneration of Chinese fir, we recommend periodical thinning to increase light into the understory after successful seedling emergence. We also recommend sowing seeds deeper into the litter to improve soil contact and moisture conditions.