马尾松(Pinus massoniana)人工林林窗对土壤不同形态活性有机碳的影响

研究了四川盆地低山丘陵区马尾松人工林不同大小林窗对表层土壤活性有机碳(水溶性有机碳、微生物量碳、易氧化碳)含量、分配比例及碳库管理指数的影响。结果表明:(1)林窗下土壤微生物量碳含量与分配比例较林下土壤有所升高,而水溶性有机碳与易氧化碳含量及水溶性有机碳分配比例有所降低。(2)林窗大小显著影响林窗中心土壤活性有机碳含量与分配比例。随林窗面积增大,水溶性有机碳、微生物量碳与易氧化碳含量呈现较为一致的升高趋势;水溶性有机碳和微生物量碳分配比例也升高,易氧化碳分配比例先下降后升高,稳定态碳先升高后降低;总体表现为较大林窗(900—1225m2)微生物活性强,活性有机碳含量高,且有机碳库稳定性较好。(3)土壤碳库管理指数随林窗面积增大无显著变化,但与各形态活性有机碳含量及总有机碳含量显著相关,说明土壤碳库管理指数能够相对全面地反映林窗大小对土壤碳库的影响。

Effect of nutrient level on phytoplankton community structure in different water bodies

Increasing levels of pollution within water bodies can cause eutrophication and an associated rapid growth in and reproduction of phytoplankton. Although most frequently occurring in bodies of water such as lakes and dams, in recent years an increasing number of river systems in China have suffered serious algal blooms. The community structure of phytoplankton may differ, however, dependent on the hydrodynamic conditions and nutrient levels within the water body. The field investigation results obtained from a stagnant river in Suzhou City and Taihu Lake, China, showed that in water with higher concentrations of nitrogen and phosphorus, Chlorophyta became the predominant species and in water with lower concentrations of nitrogen and phosphorus, Cyanobacteria became the predominant species. Growth experiments with competitive species, Microcystis aeruginosa Kutz and Scenedesmus quadricauda （Turp.）, were conducted at three different nutrient levels. The biomass of algae in pure and mixed cultures was measured under conditions of different N/P ratios at oligotrophic, eutrophic and hypertrophic nutrient levels. The results indicated that the most suitable state for the growth and reproduction of M. aeruginosa and S. quadricauda were eutrophic conditions in both pure and mixed cultures. Under competition, however, the lower medium nutrient levels favoured M. aeruginosa, while the higher medium nutrient levels better suited S. quadricauda. Under similar hydrodynamic conditions, the community structure of phytoplankton in the water body was determined by the dominant species in competition for nutrients.

Effects of a decade of organic fertilizer substitution on vegetable yield and soil phosphorus pools, phosphatase activities, and the microbial community in a greenhouse vegetable production system

Partial substitution of chemical fertilizers by organic amendments is adopted widely for promoting the availability of soil phosphorus(P)in agricultural production.However,few studies have comprehensively evaluated the effects of longterm organic substitution on soil P availability and microbial activity in greenhouse vegetable fields.A 10-year(2009–2019)field experiment was carried out to investigate the impacts of organic fertilizer substitution on soil P pools,phosphatase activities and the microbial community,and identify factors that regulate these soil P transformation characteristics.Four treatments included 100%chemical N fertilizer(4 CN),50%substitution of chemical N by manure(2 CN+2 MN),straw(2 CN+2 SN),and combined manure with straw(2 CN+1 MN+1 SN).Compared with the 4 CN treatment,organic substitution treatments increased celery and tomato yields by 6.9-13.8%and 8.6-18.1%,respectively,with the highest yields being in the 2 CN+1 MN+1 SN treatment.After 10 years of fertilization,organic substitution treatments reduced total P and inorganic P accumulation,increased the concentrations of available P,organic P,and microbial biomass P,and promoted phosphatase activities(alkaline and acid phosphomonoesterase,phosphodiesterase,and phytase)and microbial growth in comparison with the 4 CN treatment.Further,organic substitution treatments significantly increased soil C/P,and the partial least squares path model(PLS-PM)revealed that the soil C/P ratio directly and significantly affected phosphatase activities and the microbial biomass and positively influenced soil P pools and vegetable yield.Partial least squares(PLS)regression demonstrated that arbuscular mycorrhizal fungi positively affected phosphatase activities.Our results suggest that organic fertilizer substitution can promote soil P transformation and availability.Combining manure with straw was more effective than applying these materials separately for developing sustainable P management practices.

Nutrient cycling characteristics of Quercus acutissima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.

Rhizosphere soil bacterial community composition in soybean genotypes and feedback to soil P availability

Soil with low phosphorus (P) availability and organic matter contents exists in large area of southwest of China, but some soybean genotypes still show well adaptations to this low yield farmland. However, to date, the underlying mechanisms of how soybean regulates soil P availability still remains unclear, like microbe-induced changes. The objective of the present study was to compare the differences of rhizosphere bacterial community composition between E311 and E109 in P-sufficiency (10.2 mg kg^-1) and P-insufficiency (5.5 mg kg^-1), respectively, which then feedback to soil P availability. In P-sufficiency, significant differences of the bacterial community composition were observed, with fast-growth bacterial phylum Proteobacteria, genus Dechloromonas, Pseudomonas, Massilia, and Propionibacterium that showed greater relative abundances in E311 compared to E109, while in P-insufficiency were not. A similar result was obtained that E311 and E109 were clustered together in P-insufficiency rather than in P-sufficiency by using principal component analysis and hierarchical clustering analysis. The quadratic relationships between bacterial diversity and soil P availability in rhizosphere were analyzed, confirming that bacterial diversity enhanced the soil P availability. Moreover, the high abundance of Pseudomonas and Massilia in the rhizosphere of E311 might increased the P availability. In the present study, the soybean E311 showed capability of shaping rhizosphere bacterial diversity, and subsequently, increasing soil P availability. This study provided a strategy for rhizosphere management through soybean genotype selection and breeding to increase P use efficiency, or upgrade middle or low yield farmland.

Microbial community diversity analysis of <i>Panax ginseng</i>rhizosphere and non-rhizosphere soil using randomly amplified polymorphic DNA method

DNA sequence diversities of soil microbial communities in rhizosphere and non-rhizosphere of 1 - 6 years Panax ginseng were evaluated by random amplified polymorphic DNA (RAPD). Total genomic DNA of soil samples were amplified by twenty-four out of two hundred random primers. The products were separated in agarose gel, and 359 and 181 reliable fragments were generated, of which, 324 and 123 were polymorphic. The gene diversity index, Shannon’s information index, and similarity coefficient were calculated, and results showed that, diversity of soil microbial community at DNA level was present. Furthermore, with the increasing of P. ginseng growing at one site, deference on soil microbial community DNA sequence between rhizosphere and non-rhizosphere tend to be more and more significant. In addition, RAPD technique was proved to be an effective tool to assess the diversity of soil microbial communities. From results we deduced that, the ecological function that performed by soil microbes may changed following the change of microbial community in rhizospheric and non-rhizospheric soils, and finally broke the balance of soil nutrition and energy cycle, soil spatial structure, microbial ecology etc.

Development,differentiation,and material distribution of secondary phloem in Pinus massoniana

Phloem is the woody tissue for the storage and long-distance transport of organic matter in vascular bundles.To reveal the process of secondary phloem development and differentiation in Pinus massoniana,the structure of the secondary phloem and the distribution of cell inclusions were observed by histochemical staining,spontaneous fluorescence of phenolic substances and cell segregation.Based on tissue development and differentiation characteristics of P.massoniana secondary phloem,the secondary phloem development was divided into seven stages:the functional phloem stage;the sieve cell lignification stage;the phloem ray bending stage;the parenchyma cell dedifferentiation and division stage;the dedifferentiated parenchyma cell population formation stage;the periderm alteration stage,and the rhytidome stage.An analysis of cell morphology and inclusion distribution characteristics showed that the sieve cells were deformed during lignification,the quantities of parenchyma and resin ducts increased with development and the crystal content in cells,as well as the levels of sugars and lipids in phloem parenchyma cells,increased with development.The results indicate that the P.massoniana phloem first lost longitudinal transport function and then increased its secretory,storage and mechanical functions.Ultimately,the parenchyma differentiated into the cortex and periderm,and the tissue outside the new periderm lignified to form the rhytidome,which fully developed into the protective tissue of the stem.

On microbial community of Pyropia haitanensis by metagenomic analysis

Microorganisms plays an important role in the growth of Pyropia haitanensis.To understand the structural and functional diversity of the microorganism community of P.haitanensis(PH40),the associated metabolic pathway network in cluster of orthologous groups(COG)and Kyoto Encyclopedia of Genes and Genomes(KEGG),and carbohydrate-active enzymes(CAZymes)were explored in metagenomic analysis.DNA extraction from gametophytes of P.haitanensis was performed first,followed by library construction,sequencing,preprocessing of sequencing data,taxonomy assignment,gene prediction,and functional annotation.The results show that the predominant microorganisms of P.haitanensis were bacteria(98.98%),and the phylum with the highest abundance was Proteobacteria(54.64%),followed by Bacteroidetes(37.92%).Erythrobacter(3.98%)and Hyunsoonleella jejuensis(1.56%)were the genera and species with the highest abundance of bacteria,respectively.The COG annotation demonstrated that genes associated with microbial metabolism was the predominant category.The results of metabolic pathway annotation show that the ABC transport system and two-component system were the main pathways in the microbial community.Plant growth hormone biosynthesis pathway and multi-vitamin biosynthesis functional units(modules)were the other important pathways.The CAZyme annotation revealed that the starch might be an important carbon source for microorganisms.Glycosyl transferase family 2(GT2)and glycosyl transferase family 3(GT3)were the highly abundant families in glucoside transferase superfamily.Six metagenome-assembled genomes containing enzymes involved in the biosynthesis of cobalamin(vitamin B 12)and indole-3-acetic acid were obtained by binning method.They were confirmed to belong to Rhodobacterales and Rhizobiales,respectively.Our findings provide comprehensive insights into the microorganism community of Pyropia.

Energy Blockchain in Smart Communities: Towards Affordable Clean Energy Supply for the Built Environment

The rapid growth of distributed renewable energy penetration is promoting the evolution of the energy system toward decentralization and decentralized and digitized smart grids.This study was based on energy blockchain,and developed a dual-biding mechanism based on the real-time energy surplus and demand in the local smart grid,which is expected to enable reliable,affordable,and clean energy supply in smart communities.In the proposed system,economic benefits could be achieved by replacing fossil-fuel-based electricity with the high penetration of affordable solar PV electricity.The reduction of energy surplus realized by distributed energy production and P2P energy trading,within the smart grid results in less transmission loss and lower requirements for costly upgrading of existing grids.By adopting energy blockchain and smart contract technologies,energy secure trading with a low risk of privacy leakage could be accommodated.The prototype is examined through a case study,and the feasibility and efficiency of the proposed mechanism are further validated by scenario analysis.

南京地区黑松、马尾松松材线虫病病、健木pH值的比较

分别对黑松Pinusthumbergii和马尾松P massoniana松材线虫病健木的pH值进行了比较 ,通过方差分析 ,确认其病、健木pH值差异是否显著 ,以期获得利用指示剂对伐倒木进行快速检验可靠性的科学依据 .结果表明 ,黑松病、健木pH值的差异极显著 ,因此 ,通过适当指示剂在伐倒木上的颜色反应进行松材线虫病的检验是可靠的 ,其可靠性可达 95 %以上 .马尾松病、健木pH值差异不显著 ,但是将所得数据进行平均数的差异显著性检验 (t检验 ) ,当概率值为 0 2 0时 ,则差异显著 ,因此该种检疫检验方法对马尾松来说 ,可靠性较低 ,仅为80 % .经分析 ,其可靠性较低的原因可能受所取试样含水量的影响 .可见 。

马尾松二代无性系生长和针叶N/P化学计量特征

[目的]在土壤有效P匮乏的立地条件下,揭示针叶N、P含量及其化学计量比与马尾松生长性状的相关性。[方法]以马尾松二代育种群体内30个无性系为试验对象,野外调查11年生时马尾松二代无性系树高、胸径等生长性状与针叶N、P含量及其化学计量比的相关性。[结果]结果表明:(1)各生长性状在马尾松二代无性系间差异显著,且无性系重复力较高,均达到0.95以上。马尾松成熟针叶和当年生针叶N、P含量及N/P在二代无性系间差异均达显著水平;(2)相关分析表明,马尾松二代无性系树高、胸径与成熟针叶和当年生针叶N含量、N/P均呈显著或极显著正相关,与成熟针叶N/P的相关系数分别为0.608 6和0.542 8,与当年生针叶N/P的相关系数分别为0.515 9和0.679 2;(3)基于主要生长性状、针叶N和P含量及其化学计量比,可将30个马尾松二代无性系聚为4类:类群1无性系树高、胸径等生长表现优良,成熟针叶N/P较高,而当年生针叶N/P相对较低;类群2无性系树高、胸径等生长表现较好,成熟针叶和当年生针叶N/P值在30个无性系中居中间水平;类群3占试验无性系总数的一半,树高、胸径等生长表现一般,成熟针叶与当年生针叶N/P相差较大,大部分无性系成熟针叶N/P较低,而当年生针叶N/P相对较高;类群4树高、胸径等生长表现较差,成熟针叶和当年生针叶N/P均较低。[结论]在贫P立地下,马尾松二代亲本无性系C13(7750×1126)和C14(3201×1123)各生长指标均较高,可能是通过调整当年生针叶和成熟针叶的养分分配,增加了当年生针叶对限制其生长的P素的再利用和再吸收,促进了N素的吸收,调整了当年生针叶和成熟针叶的N/P,以形成特定的养分分配机制。

持续N沉降对低P下2年生马尾松苗木菌根共生影响

【目的】研究低P胁迫下N沉降持续增加对马尾松菌根化苗木生长和土壤养分的影响,为有效调控以充分发挥菌根潜力提高苗木对土壤P表的吸收、利用效率提供理论依据。【方法】以马尾松优良家系为试材,设置持续2个生长季的N沉降与同质低P(介质表层与底层均缺P)、异质低P(介质表层P丰富、底层缺P)耦合条件下菌根共生的盆栽试验,量化分析不同低P胁迫下持续N沉降对马尾松菌根化苗木生物量积累、根系发育、N和P效率以及菌根土养分等的影响。【结果】1)同质低P下,土壤中N素累积、P素相对严重匮缺,从而显著抑制马尾松苗木的菌根侵染,降低菌根化苗木的生物量积累;异质低P下,土壤原有的N/P改变,从而促进菌根真菌对马尾松苗木的侵染及植株对N和P素的吸收,最终促进苗木生物量的增加。2)同质低P下,植株的N/P显著增加,导致苗木生长受P素的限制,而对N素的增加不敏感,从而抑制菌根化苗木的生长;异质低P下,持续的N输入增加菌根作用的有效性,促进苗木对土壤P素和N素的吸收,植株N/P降低,从而改善苗木的生长状况。3)同质低P下,菌根土养分状况改善,土壤N和P含量均增加,p H值未显著改变,这可能因为菌根对土壤作用的有效性增加;异质低P下,接种菌根菌对土壤养分的抑制程度降低,土壤p H值显著降低。【结论】2种P素环境下,菌根作用的有效性对持续增加的N沉降的响应不同:同质低P下,菌根土养分状况得以改善,但随着土壤有效N的不断累积,导致土壤P素相对严重匮缺,植株N/P显著增加,使苗木生长受P素的限制程度增加,最终抑制苗木的生长;异质低P下,持续N沉降降低菌根菌对土壤养分的抑制程度,改变土壤原有的N/P,增加菌根作用的有效性,最终显著增加苗木的生物量。

不同N源对马尾松幼苗根/土界面pH及P素有效性的影响

用根垫—冰冻切片法研究了不同N源处理对马尾松幼苗根/土界面pH及P有效性的影响。结果表明:较对照处理,施加硝态N(NO3--N)与铵态N(NH4+-N)时,根/土界面pH分别增加和降低;不同N源配施易溶性P(PS)时,近根面处pH变化很小,有效P含量均明显增加;配施难溶性矿物P(PR)时,硝态N引起的根/土界面pH增加的幅度增大,近根面处有效P含量未表现出增加,而铵态N引起的根/土界面pH降低的幅度减小,近根面处有效P含量明显增加,表明铵态N处理引起的根系质子(H+)分泌是根/土界面处难溶性矿物P活化的主要因素。

A Visiting Scholar Report of the Writing Center at the University of Kansas

This article introduces the Writing Center of the University of Kansas on levels of administration, training, hiring and practicing.

Indigenous arbuscular mycorrhizal fungi play a role in phosphorus depletion in organic manure amended high fertility soil

The species richness and propagule number of arbuscular mycorrhizal fungi(AMF)are high in intensively-managed agricultural soils.Past research has shown that AMF improve crop phosphorus(P)uptake under low soil P conditions,however it is unclear if AMF play a role in high Olsen-P soils.In this study,we investigated whether native fungal benefits exist under high P input field conditions in-situ and contribute to P utilization.We installed in-grow tubes which were sealed with different membrane pore sizes(30 or 0.45μm)to allow or prevent AMF hyphae access to the hyphal compartment and prevent cotton roots from penetrating the chamber.We used the depletion of soil available P(Olsen-P)in the hyphae accessed compartment to indicate P uptake by the native AMF community.Our results showed that the native AMF mediated P depletion and microbial biomass P(MBP)turnover and caused the largest Olsen-P depletion ratio and MBP turnover ratio in the high P treatments(Olsen-P:78.29 mg kg^(-1)).The cotton roots in each fertilization regime were colonized by a unique AMF community and Glomus and Paraglomus were the dominant genera,implying the longterm fertilization regimes domesticated the AMF community.We conclude that native AMF caused the P depletion and P turnover even under high soil Olsen-P conditions.

Effect of Planting Eucalyptus Trees on Runoff Depth and Its Processes of Forestland Natural Watersheds

The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.

Experimental Study in Out-Door Tanks of N and P Uptake by the Aquatic Communities of Lake Kinneret

Two trials (1st Trial-46 and 2nd Trial-64 hrs duration) experiment in 8 out-door tanks (5 m3) were carried out with similar design: 4 fish densities (0, 1, 5, and 10), 2 densities of zooplankton (high and low) and 4 increasing levels of P and N concentrations of nutrient enrichments. The consecutive changes of N and P concentrations were measured at 3 (Trial 1) and 4 (Trial 2) time intervals. It was found that nutrient uptake of the entire community, which is the differences between initial and final concentrations, was mostly affected by the initial enrichment. The ecological implications are discussed.

A P2P Platform for Collaborative Aggregated Multimedia Sharing

Peer-to-peer technologies have emerged as a powerful and scalable communication model for large scale content shar-ing. However, they are not yet provided with optimized heterogeneous aggregated content management functionality since they lack rich semantic specifications. To overcome these shortcomings, we elaborated a reference model of P2P architecture for a dynamic aggregation, sharing and retrieval of heterogeneous multimedia contents (simple or aggre-gated). This architecture was mainly developed under the CAM4Home European research project and is fully based on the CAM4Home semantic metadata model. This semantic model relies on RDF (Resource Description Framework) and is rich (but simple enough), extensible and dedicated for the description of any kind of multimedia content.In this paper, we detail and evaluate an original semantic-based community network architecture for heterogeneous multimedia con-tent sharing and retrieval. Within the presentedarchitecture, multimedia contents are managed according to their asso-ciated CAM4Home semantic metadata through a structured P2P topology. This topology relies on a semantically en-hanced DHT (Distributed Hash Table) and is also provided with an additional indexing system for offering semantic storage and search facilities and overcoming the problem of exact match keywords in DHTs.

Differences in arthropod communities between island and inland Masson pine forests infested by pine wilt disease in Zhejiang Province

The invasion of Bursaphelenchus xylophilus （pine wood nematode, PWN） carried by Monochamus alternatus predominately attacks Masson pine （Pinus massoniana） forests and causes great economic losses in China. In this study, we assessed whether the effect of the invasion of PWN is different between island and inland forests. Arthropods were sampled in Fuyang （inland） and Zhoushan （island） counties in Zhejiang Province with sweep netting and light traps at four plots. During two field periods （May to June 2004 and September to October 2005） a total of 21,916 insects, representing 384 species belonging to 99 families and 15 orders, were collected in the sample plots from the island, whereas, from the inland forest a total of 29,262 insects, representing 308 species belonging to 96 families and 13 orders, were found. A hierarchical cluster analysis （HCA） and one-way ANOVA, based on the composition of different arthropod guilds, were performed. The results showed that there was no significant difference in the composition of arthropod communities at the family level between inland and island. But these two habitats had a significant effect on the composition of species, individuals, sub-communities and energy class levels. Statistically, the composition of the two orders, Lepidoptera and Diptera, in the two habitats were significantly different.

Towards Optimal Planning and Scheduling in Smart Homes

This research addresses the planning and scheduling problem in and among the smart homes in a community microgrid. We develop a bi-linear algorithm, named ECO-Trade to generate the near-optimal schedules of the households’ loads, storage and energy sources. The algorithm also facilitates Peer-to-Peer (P2P) energy trading among the smart homes in a community microgrid. However, P2P trading potentially results in an unfair cost distribution among the participating households. To the best of our knowledge, the ECO-Trade algorithm is the first near-optimal cost optimization algorithm which considers the unfair cost distribution problem for a Demand Side Management (DSM) system coordinated with P2P energy trading. It also solves the time complexity problem of our previously proposed optimal model. Our results show that the solution time of the ECO-Trade algorithm is mostly less than a minute. It also shows that 97% of the solutions generated by the ECO-Trade algorithm are optimal solutions. Furthermore, we analyze the solutions and identify that the algorithm sometimes gets trapped at a local minimum because it alternately sets the microgrid price and quantity as constants. Finally, we describe the reasons of the cost increase by a local minimum and analyze its impact on cost optimization.