[Sampling time of living leaf for estimating phytolith-occluded organic carbon sequestration rate of Phyllostachys edulis.] / æ¯›ç«¹æž—æ¤ç¡ ä½“ç¢³å°å­˜é€ŸçŽ‡ä¼°ç®—çš„æœ€ä½³é²œå¶é‡‡æ ·æ—¶é—´.

Monthly phytolith-occluded organic carbon (PhytOC) content in living leaves and litterfall of Moso bamboo (Phyllostachys edulis) were measured for a year. The PhytOC sequestration rate in living leaves of different months were compared with that in annual litterfall to determine the optimum sampling time of living leaves for estimating PhytOC sequestration rate of Moso bamboo. The contents of phytoliths and PhytOC in living leaves of Moso bamboos were 23.45-101.07 g·kg-1 and 0.73-1.98 g·kg-1, respectively, with significant difference among different months. The monthly PhytOC sequestration rates of living leaves of Moso bamboo in different months ranged from 0.75 to 7.68 kg·hm-2·a-1. The maximum and minimum rates of the PhytOC sequestration occurred in December and April respectively, with significant difference between them. There was no difference between the PhytOC sequestration rate in living leaves of Moso bamboos in February or December and that of litterfall in the whole year. Therefore, February or December should be the optimal month of sampling living leaves for estimating the PhytOC sequestration rate of Moso bamboo stands.

[Evolution pattern of phytolith-occluded carbon in typical forest-soil ecosystems in tropics and subtropics, China.] / çƒ­å¸¦ã€äºšçƒ­å¸¦å ¸åž‹æ£®æž—-åœŸå£¤ç³»ç»Ÿæ¤ç¡ ä½“ç¢³æ¼”å˜è§„å¾‹.

Samples of fresh leaves and leaf litter, as well as soils taken from 0-10 and 10-30 cm layers, were collected in four types of typical forest ecosystems both in subtropical (Phyllostachys pubescens, Pinus massoniana, Cycloba lanopsisglauca, and Cunninghamia lanceolata stands) and in tropical climates (Vatica mangachapoi, Musa basjoo, Heveabrasiliensis, and Acacia mangium stands) for measurement of PhytOC (phytolith-occluded organic carbon) contents. The phytoliths in both leaves and soil samples were extracted by a microwave digestion method and their PhytOC contents were determined by alkali dissolution-spectrophotometry method. It was found that, among the four types of subtropical forests, the PhytOC contents of leaves, litter and 0-10 cm soil layer were the highest in P. massoniana stand (230.24, 229.17 and 20.87 g·kg-1), the lowest in P. pubescens stand (30.55, 37.37, and 3.38 g·kg-1), and the PhytOC content of the 10-30 cm soil layer was the highest in C. glauca stand (18.54 g·kg-1), and the lowest in P. pubescens stand (2.90 g·kg-1). For the four tropical forests, A. mangium stand (377.66 g·kg-1) and V. mangachapoi stand (46.83 g·kg-1), respectively, deposited the highest and lowest contents of PhytOC in the leaves, while the highest and lowest contents of PhytOC in the litter were observed in H. brasiliensis stand (218.23 g·kg-1) and M. basjoo stand (27.66 g·kg-1), respectively. Also among the tropical forests, the highest PhytOC contents in the 0-10 cm and 10-30 cm soil layers were observed in A. mangium stand (23.84 and 24.90 g·kg-1), while the lowest values occurred in M. basjoo stand (3.89 and 3.93 g·kg-1). The PhytOC contents in transitioning from leaves to soils (0-10 cm layers) decreased by 97.4% for C. lanceolata, 94.9% for C. glauca, 90.9% for P. massoniana, and 88.9% for P. pubescens in the subtropics, and by 95.9% for H. brasiliensis, 93.7% for A. mangium, 93.3% for M. basjoo, 63.7% for V. mangachapoi in the tropics. There was no significant difference in PhytOC contents between leaves and litter for the following five forest types: P. pubescens, P. massoniana, C. lanceolata, V. mangachapoi and H. brasiliensis. However, significantly higher PhytOC contents in leaves than in litters were measured in C. glauca, M. basjoo, and A. mangium. The findings that significantly lower PhytOC contents occurred in soils than in fresh leaves and leaf litter regardless of type of forest ecosystem suggested that phytolith was not stable during the pathway from plants to soil via the forest litter.

Production of carbon occluded in phytolith is season-dependent in a bamboo forest in subtropical China.

Carbon (C) occluded in phytolith (PhytOC) is a stable form of C; when PhytOC is returned to the soil through litterfall it is stored in the soil which can be an effective way for long-term C sequestration. However, few estimates on the rate of PhytOC input to the soil are available. To better understand the seasonal dynamics of PhytOC production and the annual rate of stable C sequestration through PhytOC input, we quantified the monthly litterfall, phytolith and PhytOC return to the soil over a year in a typical Lei bamboo (Phyllostachys praecox) forest in subtropical China. The monthly litterfall ranged between 14.81 and 131.18 g m(-2), and the phytolith concentration in the monthly litterfall samples ranged between 47.21 and 101.68 g kg(-1) of litter mass, with the PhytOC concentration in the phytolith ranged between 29.4 and 44.9 g kg(-1) of phytolith, equivalent to 1.8-3.6 g kg(-1) of PhytOC in the litterfall (based on litterfall dry mass). The amount of phytolith input to the soil system was 292.21 ± 69.12 (mean ± SD) kg ha(-1) yr(-1), sequestering 41.45 ± 9.32 kg CO2-e ha(-1) yr(-1) of C in the studied Lei bamboo forest. This rate of C sequestration through the formation of PhytOC found in this study falls within the range of rates for other grass-type species reported in the literature. We conclude that return of C occluded in phytolith to the soil can be a substantial source of stable soil C and finding means to increase PhytOC storage in the soil should be able to play a significant role in mitigating the rapidly increasing atmospheric CO2 concentration.

Long-term intensive management increased carbon occluded in phytolith (PhytOC) in bamboo forest soils.

Carbon (C) occluded in phytolith (PhytOC) is highly stable at millennium scale and its accumulation in soils can help increase long-term C sequestration. Here, we report that soil PhytOC storage significantly increased with increasing duration under intensive management (mulching and fertilization) in Lei bamboo (Phyllostachys praecox) plantations. The PhytOC storage in 0-40 cm soil layer in bamboo plantations increased by 217 Mg C ha(-1), 20 years after being converted from paddy fields. The PhytOC accumulated at 79 kg C ha(-1) yr(-1), a rate far exceeding the global mean long-term soil C accumulation rate of 24 kg C ha(-1) yr(-1) reported in the literature. Approximately 86% of the increased PhytOC came from the large amount of mulch applied. Our data clearly demonstrate the decadal scale management effect on PhytOC accumulation, suggesting that heavy mulching is a potential method for increasing long-term organic C storage in soils for mitigating global climate change.

[Uptake and accumulation characteristics of silicon and other nutritional elements in different age Phyllostachys praecox plants].

The samples of different age (1-4 years old) Phyllostachys praecox plants and their organs (leaf, branch, and culm) were collected from their main production area in Lin' an County, Zhejiang Province of East China to study the contents and the uptake and accumulation characteristics of silicon and other nutritional elements, as well as the interrelations between Si and other nutrient elements. In the P. praecox plants, the C content in aboveground part was in the order of culm > branch> leaf, whereas the Si, N, P, K, Ca, Mg, Al, Fe and Mn contents were in the order of leaf > branch > culm. Mn was mainly accumulated in leaf, while the other nine nutrient elements were mainly accumulated in the culm of 1-year old plants. The average Si content in the aboveground part of 3-4 year old plants was 13.66 g x kg(-1), suggesting that P. praecox belonged to Si accumulation plant. The leaf N, P, K, and Mg contents decreased, while the C, Al, and Mn contents increased with increasing plant age. The Si uptake by the aboveground part was mainly occurred in the second year (57.1%), while the N and K uptake was mainly in the first two years (67.7% - 93.7%). Thereafter, the N and K flowed out from the aboveground part, with the outflow rates reached 19.1% - 39.1% of the total accumulated amounts. The Si in P. praecox was significantly correlated with Ca, Al, and Mn, and negatively correlated with N, P, K, and Mg.