Subtropical forest macro-decomposers rapidly transfer litter carbon and nitrogen into soil mineral-associated organic matter

Background:Forest soils in tropical and subtropical areas store a significant amount of carbon.Recent framework to assess soil organic matter(SOM)dynamics under evolving global conditions suggest that dividing bulk SOM into particulate and mineral-associated organic matter(POM vs.MAOM)is a promising method for identifying how SOM contributes to reducing global warming.Soil macrofauna,earthworms,and millipedes have been found to play an important role in facilitating SOM processes.However,how these two co-existing macrofaunae impac the litter decomposition process and directly impact the formation of POM and MAOM remains unclear.Methods:Here,we set up a microcosm experiment,which consisted of 20 microcosms with four treatments earthworm and litter addition(E),millipedes and litter addition(M),earthworm,millipedes,and litter addition(E+M),and control(only litter addition)in five replicates.The soil and litter were sterilized prior to beginning the incubation experiment to remove any existing microbes.After incubating the samples for 42 days,the litte properties(mass,C,and N contents),soil physicochemical properties,as well as the C and N contents,and POM and MAOM^(13)C abundance in the 0–5 and 5–10 cm soil layers were measured.Finally,the relative influences o soil physicochemical and microbial properties on the distribution of C and N in the soil fractions were analyzed Results:The litter mass,C,and N associated with all four treatments significantly decreased after incubation especially under treatment E+M(litter mass:-58.8%,litter C:-57.0%,litter N:-75.1%,respectively),while earthworm biomass significantly decreased under treatment E.Earthworm or millipede addition alone showed no significant effects on the organic carbon(OC)and total nitrogen(TN)content in the POM fraction,but join addition of both significantly increased OC and TN regardless of soil depth.Importantly,all three macrofauna treatments increased the OC and TN content and decreased the^(13)C abundance in the MAOM fraction.More than65%of the total variations in the distribution of OC and TN throughout the two fractions can be explained by a combination of soil physicochemical and microbial properties.Changes in the OC distribution in the 0–5 cm soi layer are likely due to a decrease in soil pH and an increase in arbuscular mycorrhizal fungi(AMF),while those in the 5–10 cm layer are probably caused by increases in soil exchangeable Ca and Mg,in addition to fungi and gram-negative(GN)bacteria.The observed TN distribution changes in the 0–5 cm soil likely resulted from a decrease in soil pH and increases in AMF,GN,and gram-negative(GP)bacteria,while TN distribution changes in the 5–10 cm soil could be explained by increases in exchangeable Mg and GN bacteria.Conclusions:The results indicate that the coexistence of earthworms and millipedes can accelerate the litte decomposition process and store more C in the MAOM fractions.This novel finding helps to unlock the processe by which complex SOM systems serve as C sinks in tropical forests and addresses the importance of soil mac rofauna in maintaining C-neutral atmospheric conditions under global climate change.

Millipede forming-a new metal forming approach

Millipede Forming is a novel metal forming method that has been proposed and developed recently.It can be applied to overcome fundamental limitations in conventional roll forming,and,in addition,used for incremental forging and integrated into a strip casting or extrusion process for downstream thickness reduction. In this new method,there are two main principles:①the use of an optimal transitional surface or space linking of the incoming material to the outgoing product,and②implementation of a method to feed the material through the forming device so that it conforms with this ideal space and the required deformation is imposed on it by the tooling. The system described here is called 'Millipede forming' because deformation is accomplished in a large number of small steps.A prototype has been built to demonstrate the working principle applied to the replacement of a roll forming process;it can be used to produce simple profiles within a forming length an order of magnitude shorter than the conventional process. In this paper,the working principle of 'Millipede forming' is introduced and some fundamental research on forming a channel section and a circular tube is discussed.Following the success of the small scale prototype, research on a full scale pilot machine has been proceeding.It is expected that this process can be developed and extended as a useful alternative to conventional roll forming,incremental forging and within a strip casting or other novel strip material(e.g.nanostructured metals) system.

十年后的硬盘技术:千足虫MILLIPEDE

现在硬盘容量大了,但毛病也不少。许多硬盘都会在出现几个物理坏道后莫名其妙地完蛋,而善良的人们都会把这些情况归罪于病毒。时间一久,人们对硬盘自身缺陷造成的短命麻木了。我们为什么不能用新的技术来取代上个世纪70年代就使用的温彻斯特硬盘(俗称“温盘”,即目前的硬盘)技术呢?作为硬盘业的先驱勇敢地迈出革命性的第一步,而他们提供给我们的答案就是MiLLiPEDE(直译为“千足虫”)！