Effect Of Parent Rock And Bamboo Age On Phytolith-occluded Carbon In Moso Bambooforest

Phytoliths also referred to as plant opal,are a kind of amorphous silicified mineral precipitated in cell walls,cavities,and intercellular spaces of plants as a result of biomineralization of soluble silicic acid?H4SiO4?within plants.Organic carbon encapsulated in the phytoliths during the formation process of the phytoliths is called Phytolith-occluded carbon?PhytOC?.Phytoliths have the characteristics of high temperature resistance and anti-decomposition and they can accumulate and preserve in the soils for thousands of years.Therefore,PhytOC is considered as one of the important ways to increase long-term sequestration carbon in soils.Moso bamboo?Phyllostachys eduli?has been proven to be a typical rich-silicon graminaceous plant and is widely distributed in the Yangtze River Basin and southern provinces in China.Moso bamboo is a bamboo species of the largest platation area and has characteristics of fast growth,high biomass,and excellent ecological efficiency.Morever,it has great phytolith accumulation ability and is a huge PhytOC sink.Study of the effects of the parent rock and bamboo ages on the contents and storages of phytolith and PhytOC in the bamboo ecosystem,and exploration of the factors affecting production and stability of phytolith and PhytOC in the bamboo ecosystem can provide a theoretical basis for the estimation of Phyt OC sequestration potential in the forest ecosystems.The purposes of this study were to?1?determine the accumulation characteristics and spatial distribution of the phytolith and PhytOC in the soils derived from the different types of rocks?granite,sand shale,and tuff?and different organs of bamboo plants with the different bamboo age?1 year,3 years?and?2?estimate the PhytOC storages in Moso bamboo ecosystem with different soils derived from different parent rocks.This study selected Moso bamboo stands with different bamboo age?1 year,3 years?planted in the soils derived the different types of rocks?granite,sand shale,and tuff?as research subjects and collected the sample of leave,branch,and culm as well as soil samples of 0¹0 cm,10³0 cm,30⁶0 cm,and 60¹00 cm depths.The phytoliths in the samples of plants and soils were extracted by a microwave digestion method and the phytOC contents in the phytoliths were determined by the alkaline dissolution method.The main results and conclusions are as follows:1.Parent rocks and bamboo ages had a significant impact on the contents of silicon,phytilith,and PhytOC/dry biomass.The average contents of the phytilith and the PhytOC /dry biomass in the bamboo leaves of bamboo plants planted in different parent rocks were in the order: grantie(33.19 g·kg^-1)> sand shale(32.64 g·kg^-1)> tuff(24.51 g·kg^-1)and grantie(105.81 g·kg^-1)> sand shale(93.50 g·kg^-1)> tuff(59.40 g·kg^-1),respectively.The contents of phytolith,PhytOC and PhytOC /dry biomass in the leaves of 3-year old bamboo plants were greater than > 1-year old ones.Parent rocks had a significant impact on the contents of Si and phytolith in the leaves of 3-year old bamboo plants and were in the order: sand shale > grantie > tuff.2.The contents of phytilith,PhytOC,and PhytOC /dry biomass in different bamboo plant organs showed significant variation: The contents of phytilith in different bamboo plant organs were in the order: leave(59.40¹05.82 g·kg^-1)> branch(14.40¹7.60 g·kg^-1)> culm(0.92¹.36 g·kg^-1);the content of phytilith and PhytOC /dry biomass in different bamboo plant organs were in the order: leaves > branches > culms;the C contents in phytilith in different bamboo plant organs showed contrary order: culms > branches > leaves.The contents of Si and phytolith in leaves,branches,and culms of 3-yer old bomboo plants were greater than 1-yer old ones.The C contents in phytolith in leaves,branches,and culms of 1-yer old bomboo plants were greater than 3-yer old ones3.The distribution of phytolith contents in soil profiles for different parent rocks showed great variation: the phytolith contents in the soil derived from grantie decreased with soil depths,the phytolith contents in the soils derived from from shale and tuff were slightly greater in 30⁶0 cm and 60¹00 cm soil depths than in 0¹0 cm surface soil.The phytolith contents in 0¹0 cm surface soil depths derived from different parent rocks showed significant differences.The contents of organic C in phytolith in the soils derived from different parent rocks decreased gradually with soil depths,where the PhytOC /TOC in the soils derived from different parent rocks increased gradually with soil depths.4.The total PhytOC storages in the Mose bamboo ecosystem for different parent rocks decresed in the oeder: granite?1814.30 kg·ha-1?> sand shale?1274.19 kg·ha-1?> tuff?881.79 kg·ha-1?.The largest PhytOC storages in the Mose bamboo ecosystems were obtained from the soils in which accounting for 94.26⁹7.66 % of total PhytOC storages.The PhytOC storages in different parts of Mose bamboo ecosystems for deffirent parent rocks decresed in the oeder: soil?831.15¹771.78 kg·ha-1?> leaves?15.19²4.03 kg·ha-1?> stems?16.85¹8.37 kg·ha-1?> branches?6.43¹3.31 kg·ha-1?.5.The study of correlation between the contents of PhytOC /dry biomass,phytolith,and Si in the soils and different organs of bamboo plants showed that the contents of PhytOC /dry biomass and phytoliths in the bamboo leaves correlated positive and significant with Si contents;There was no relationship between the contents of organic C in phytolith and phytoliths contents in the branches and culms;for the bamboo plants planted on the soils derived fron different parent rocks,there was no significant correlation between phytolith contents and Si contents in the most of bamboo beanches and culms,but there was significant positive correlation between in the contents of PhytOC /dry biomass and phytoliths in the bamboo branches;there was no relationship between phytolith contents and Si contents in the soils,but there was significant positive correlation between in phytolith contents in tha bamboo leaves and Si contents in the soils;there was significant positive correlation between in PhytOC storage and phytolith contents in the soils.Based on the above-mentioned results,it can be concluded that:?1?the contents of silicon,phytilith,and PhytOC /dry biomass in different organs of bamboo plants showed significant variation which was attributed to the differences of Si contents in the soil derived from different parent rocks;?2?significant correlation between the contents of PhytOC /dry biomass and and Si contents as well as between in phytolith contents in tha bamboo leaves and Si contents in the soils indicate that selection of soils with high Si contents and plants high PhytOC contents under different agro-ecosystems may provide an opportunity for enhancing terrestrial lomg-term carbon sequestration.