Aquapteridospora jiangxiensis, a new aquatic hyphomycetous fungus from a freshwater habitat in China.

During an investigation of freshwater fungi in Jiangxi province, China, a new hyphomycetous fungus, Aquapteridospora jiangxiensis, was collected and isolated. Aquapteridospora jiangxiensis is characterized by its unbranched and guttulate conidiophores with multi-septa swollen at the base, polyblastic conidiogenous cells with sympodial proliferations, and denticles, and guttulate conidia with a sheath. A photo plate of the macro- and micro-morphology and a muti-loci (ITS, LSU, SSU, TEF1 and RPB2) phylogenetic tree are provided. A key to the species of Aquapteridospora is also presented in this paper.

[Carbon density distribution characteristics and influencing factors in aerially seeded Pinus massoniana plantations]. / é£žæ’­é©¬å°¾æ¾æž—ç¢³å¯†åº¦åˆ†é ç‰¹å¾åŠå ¶å½±å“å› ç´ .

The distribution characteristics of carbon density under aerially seeded Pinus massoniana plantations in Ganzhou City of Jiangxi Province were studied. Total 15 factors, including site, stand, understory vegetation, litter and so on were selected to establish a relationship model between stand carbon density and influencing factors, and the main influencing factors were also screened. The results showed that the average carbon density was 98.29 t·hm-2 at stand level with soil layer (49.58 t·hm-2) > tree layer (45.25 t·hm-2) > understory vegetation layer (2.23 t·hm-2) > litter layer (1.23 t·hm-2). Significantly positive correlations were found among the tree, litter and soil layers, but not among the other layers. The main factors were tree density, avera-ge diameter at breast height (DBH), soil thickness, slope position, stand age and canopy density to affect carbon density in aerially seeded P. massoniana plantations. The partial correlation coefficients of the six main factors ranged from 0.331 to 0.434 with significance by t test. The multiple correlation coefficient of quantitative model I reached 0.796 with significance by F test (F=9.28). For stand density, the best tree density and canopy density were 1500-2100 plants·hm-2 and 0.4-0.7, respectively. The moderate density was helpful to improve ecosystem carbon sequestration. The carbon density increased with increasing stand age, DBH and soil thickness, and was higher in lower than middle and upper slope positions.

[Spatiotemporal dynamics of atmospheric PM2.5 and PM10 and its influencing factors in Nanchang, China]. / 南昌市空气PM2.5和PM10çš„æ—¶ç©ºåŠ¨æ€åŠå ¶å½±å“å› ç´ .

PM2.5 and PM10 have become the primary pollutants of most cities in China. Atmospheric PM2.5 and PM10 mass concentrations, meteorological factors, traffic flow from 2013 to 2015 in Nanchang were analyzed. Spatiotemporal dynamic pattern of atmospheric particulate matter pollution and the effect of weather and traffic on particle concentration change were discussed in this paper. The results showed that PM2.5(70.92 µg·m-3 in 2013 > 53.70 µg·m-3 in 2014 ＞ 43.65 µg·m-3 in 2015) and PM10(119.72 µg·m-3 in 2013 ＞ 86.11 µg·m-3 in 2014 ＞ 73.32 µg·m-3 in 2015) concentrations decreased gradually from 2013 to 2015. In addition, low concentrations of PM2.5 and PM10 in summer (average PM2.5 concentration 36.74 µg·m-3, average PM10 concentration 69.20 µg·m-3) but high concentrations in winter (average PM2.5 concentration 74.29 µg·m-3, average PM10 concentration 111.64 µg·m-3) were observed. Moreover, PM2.5 and PM10 concentrations changed with the urban-rural gradient, decreasing from the city center to suburb. The ratio of PM2.5/PM10(0.595 ＞ 0.584 ＞ 0.557) decreased year by year from 2013 to 2015 and was higher in the city center area than in the edge of city. PM2.5 and PM10 concentrations were affected by various meteorological factors and significantly related to air pressure, temperature, relative humidity, wind speed, precipitation and sunshine time. The influence of meteorological factors differed on PM2.5 and PM10 concentrations. Traffic flow significantly increased the surrounding PM2.5 concentration, but not PM10 concentration.

[Stable hydrogen and oxygen isotope compositions in soil-plant-atmosphere continuum (SPAC) in rocky mountain area of Beijing, China]. / 北京土石山区水分在土壤-植物-大气连续体(SPAC)ä¸­çš„ç¨³å®šåŒä½ç´ ç‰¹å¾.

The stable hydrogen and oxygen isotopes are environmental isotopes, which widely exist in various kinds of water. Their relative abundance variation in water can indicate the water circulation and mechanism of water use in plant. This research selected two major kinds of greening tree species, evergreen coniferous Platycladus orientalis and deciduous broad-leaved Quercus variabilis, in Beijing mountainous area, and the water movement process in soil-plant-atmosphere continuum was investigated by the variation characteristics analysis of stable hydrogen and oxygen isotope compositions in precipitation, soil water, groundwater, plant stem water and leaf water. The results showed that the meteoric water line equation of the study area was δD=7.17δ18O+1.45 (R2=0.93), and the soil evaporation line equation was δD=3.85δ18O+1.45 (R2=0.76). A certain degree of evaporation fractionation existed in the processes of rainfall infiltration into soil water. In different seasons, the δD and δ18O values of precipitation, soil water and spring water had different variation regularity. In rainy season, the mean δD and δ18O values were in order of precipitation> spring water>soil water, with the precipitation and soil water supplied spring water together; in dry season, the order was precipitation > soil water > spring water, and the precipitation and spring water both contributed to soil water. The δD and δ18O fitting line equations of stem water of P. orienta-lis and Q. variabilis were respectively δD=5.03δ18O-30.78 and δD=3.0δ18O-48.92. The uptake water of Q. variabilis was more enriched than that of P. orientalis, and the depth of Q. variabilis water uptake in soil profile was shallower than P. orientalis. The leaf water isotopic variation of Q. varia-bilis was more sensitive to atmospheric environment, with the kinetic isotopic fractionation of Q. variabilis being more enriched than that of P. orientalis, but they had the same response to variation of environmental condition.

[Effects of stand structure regulation on soil labile organic carbon in Pinus elliottii plantation].

Taking 21-year-old Pinus elliottii pure plantation as the control, effects of enrichment planting with broadleaf trees (Liquidambar fornosana) after thinning the conifer trees (P. elliottii) on soil labile organic carbon of different plantations, including 3-year-old, 6-year-old, 9-year-old P. elliottii and 21-year-old P. elliottii-L. fornosana mixed plantations, were investigated. The results showed that the contents of soil dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) significantly increased in the 6-year-old and 9-year-old plantations compared with those in the 21-year-old P. elliottii pure plantation. Soil labile organic carbon contents in the 21-year-old P. elliottii-L. fornosana mixed plantation increased significantly than those in 3-year-old, 6-year-old, 9-year-old stands, and the DOC, ROC and MBC contents increased by 113.1%, 53.3% and 54.6%, respectively, compared with those in the 21-year-old P. elliottii pure plantation. The results suggested that replanting with broadleaf trees are an effective measure to improve the soil ecological function in pure P. elliottii plantation.

[Effects of reforestation on soil chemical properties and microbial communities in a severely degraded sub-tropical red soil region].

Taking the long-term reforestation experimental base established in a severely degraded sub-tropical hilly red soil region in Taihe County of Jiangxi Province in 1991 as the object, this paper studied the changes of soil nutrients and microbial communities after 19 years reforestation of Pinus elliottii forest, Liquidambarformosana forest, and P. elliotti-L. formosana forest, with the naturally restored grassland as the control. The soil organic carbon content in the L. formosana and P. elliottii-L. formosana forests (15.16+/-3.53 and 16.42+/-0.49 g kg-1, respectively) was significantly higher than that in the control (9.30+/-1.13 g kg-1), the soil total phosphorus content was in the order of the control (0.30+/-0.02 g kg-1) > P. elliottii-L. formosana forest (0.22+/-0.04 g kg-1 ) > L. formosana forest (0.14+/-0.01 g kg-1 ), while the soil available phosphorus content was 1.66+/-0.02 mg kg-1 in L. formosana forest, 2.47+/-0. 27 mg kg- in P. elliottii-L. formosana forest, and 1. 15+/-0.71 mg kg-1 in P. elliottii forest, being significantly higher than that in the control (0.01+/-0.00 mg kg-1). The total amounts of soil microbes, the amount and percentage of soil bacteria, and the amount of inorganic and organic phosphate-solubilizing microbes in L. formosana forest and P. elliottii-L. formosana forest were all significantly higher than those in P. elliottii forest and the control, while the amount and percentage of soil fungi and the percentage of soil actinomycetes in L. formosana forest and P. elliottii-L. formosana forest were significantly lower than those in the control. The soil organic carbon content was significantly positively correlated with the percentage of soil bactera, but negatively correlated with the percentage of soil fungi and actinomycetes, while the soil available phosphorus content was significantly positively correlated with the amount of organic phosphate-solubilizing microes, but not with the amount of inorganic phosphate-solubilizing microbes. It was suggested that L. formosana forest and P. elliottii-L. formosana forest could be the recommended reforestation models in sub-tropical degraded red soil region.

[Effects of converting cultivated land into forest land on the characteristics of soil organic carbon in limestone mountain area in Ruichang, Jiangxi].

Taking the forest lands having been converted from cultivated land for 5 years in Ruichang City of Jiangxi Province as test objects, this paper studied the characteristics of soil organic carbon (SOC) under 4 different conversion models (forest-seedling integration, pure medicinal forest, bamboo-broadleaved mixed forest, and multi-species mixed forest). After the conversion from cultivated land into forestlands, the contents of SOC, microbial biomass carbon (MBC), and mineralizable carbon (PMC) in 0-20 cm soil layer increased by 24.4%, 29%, and 18.4%, respectively, compared with those under the conversion from cultivated land into wasteland (P < 0.05), which indicated that the conversion from cultivated land into forest lands significantly increased the SOC content and SOC storage. The SOC, MBC, and PMC contents in 0-10 cm soil layer were significantly higher than those in 10-20 cm soil layer (P < 0.01), and the differences between the soil layers of the four forest lands were higher than those of the wasteland. Among the 4 conversion models, forest-seedling integration had more obvious effects on SOC.

[Soil soluble organic matter, microbial biomass, and enzyme activities in forest plantations in degraded red soil region of Jiangxi Province, China].

Taking the adjacent 18-year-old pure Pinus massoniana pure forest (I), P. massoniana, Liquidamber fomosana, and Schima superba mixed forest (II), S. superba pure forest (III), L. fomosana (IV) pure forest, and natural restoration fallow land (CK) in Taihe County of Jiangxi Province as test sites, a comparative study was made on their soil soluble organic carbon (SOC) and nitrogen (SON), soil microbial biomass C (MBC) and N (MBN), and soil urease and asparaginase activities. In 0-10 cm soil layer, the pool sizes of SOC, SON, MBC, and MBN at test sites ranged in 354-1007 mg x kg(-1), 24-73 mg x kg(-1), 203-488 mg x kg(-1), and 24-65 mg x kg(-1), and the soil urease and asparaginase activities were 95-133 mg x kg(-1) x d(-1) and 58-113 mg x kg(-1) x d(-1), respectively. There were significant differences in the pool sizes of SOC, SON, MBC, and MBN and the asparaginase activity among the test sites, but no significant difference was observed in the urease activity. The pool sizes of SOC and SON were in the order of IV > CK > III > I > II, those of MBC and MBN were in the order of CK > IV > III > I > II, and asparaginase activity followed the order of IV > CK > III > II > I. With the increase of soil depth, the pool sizes of SOC, SON, MBC, and MBN and the activities of soil asparaginase and urease decreased. In 0-20 cm soil layer, the SOC, SON, MBC, MBN, total C, and total N were highly correlated with each other, soil asparaginase activity was highly correlated with SOC, SON, TSN, total C, total N, MBC, and MBN, and soil urease activity was highly correlated with SON, TSN, total C, MBC and MBN.

[Relationships of soil moisture content with precipitation and evaporation in rehabilitated forests in degraded limestone red-soil region of Jiangxi Province].

By using time series analysis, the relationships of 0-40 cm soil moisture content with precipitation and evaporation in four main rehabilitated forests in degraded limestone red-soil region of Xiushui County, Jiangxi Province were studied. The results showed that in the four rehabilitated forests, the previous month's soil moisture content had stronger effects on the current month's soil moisture content in 0-40 cm and 20-40 cm layers, but had lesser effects on that in 0-10 cm layer. The soil moisture content in 20-40 cm layer was mainly affected by current month's precipitation, while that in 0-10 cm layer was mainly affected by current month's evaporation. The correlation coefficient between current month's precipitation and soil moisture content was the largest in pure Liquidambar formosana plantation, and the auto-interrelation coefficient of soil moisture content was larger in mixed forests than in pure L. formosana plantation.