Simulating Carbon Sequestration and GHGs Emissions in Abies fabric Forest on the Gongga Mountains Using a Biogeochemical Process Model Forest-DNDC

The process-oriented model Forest-DNDC describing biogeochemical cycling of C and N and GHGs (greenhouse gases) fluxes (CO2, NO and N2O) in forest ecosystems was applied to simulate carbon sequestration and GHGs emissions in Abies fabric forest of the Gongga Mountains at southeastern edge of the Tibetan Plateau. The results indicated that the simulated gross primary production (GPP) of Abies fabric forest was strongly affected by temperature. The annual total GPP was 24,245.3 kg C ha-1 yr-1 for 2005 and 26,318.8 kg C ha-1 yr-1 for 2006, respectively. The annual total net primary production (NPP) was 5,935.5 and 4,882.2 kg C ha-1 yr-1 for 2005 and 2006, and the annual total net ecosystem production (NEP) was 4,815.4 and 3,512.8 kg C ha-1 yr-1 for 2005 and 2006, respectively. The simulated seasonal variation in CO2 emissions generally followed the seasonal variations in temperature and precipitation. The annual total CO2 emissions were 3,109.0 and 4,821.0 kg C ha-1 yr-1 for 2005 and 2006, the simulated annual total N2O emissions from forest soil were 1.47 and 1.36 kg N ha-1 yr-1 for 2005 and 2006, and the annual total NO emissions were 0.09 and 0.12 kg N ha-1 yr-1 for 2005 and 2006, respectively.     

Soil conservation assessment via climate change and vegetation growth scenarios in the Nile River basin

Soil conservation by vegetation can mitigate soil erosion hazard and prevent reductions in food productivity. However, previous research applies little consideration to the interaction between vegetation and climate change in the estimation of future soil conservation change. Therefore, based on the Revised Universal Soil Loss Equation(RUSLE), Representative Concentration Pathways(RCPs, specifically RCP4.5 and RCP8.5), and the vegetation index and precipitation datasets, we built a multivariate regression equation that considers changes in vegetation growth under climate change scenarios in the context of soil conservation. Using the Nile River basin as a case study, via our established methods, we modelled and projected the impact of vegetation and climate change on future soil conservation between 2020 and 2100, where three main results were obtained:(1) under the scenarios of RCP4.5 and RCP8.5 from 2020 to 2100, soil conservation in the Nile Basin will first increase and then decrease, with its highest value in the years 2060, at 117.72(t ha-1 y-1), and 2070, at 134.39(t ha-1 y-1).(2) Soil conservation under RCP4.5 is lower than that under the RCP8.5 scenario, with a maximum difference of 27(t ha-1 y-1) in 2040 and a minimum difference of 0.2(t ha-1 y-1) in 2100.(3) The vegetation and climate change models in 2100 had soil conservation values of 110.77(t ha-1 y-1) under RCP4.5 and 38.70(t ha-1 y-1) under RCP8.5. In conclusion, although vegetation growth can increase soil conservation in the Nile River basin, the change in precipitation can offset the soil conservation enhanced by vegetation growth.     

Simultaneous quantification of greenhouse gas and nitric oxide emissions from subtropical conventional vegetable systems: a 2-site field case study in Sichuan Basin

Quantification of greenhouse gases[nitrous oxide(N₂O)and methane(CH₄)]and nitric oxide(NO)emissions from subtropical conventional vegetable systems through multi-site field measurements are needed to obtain accurate regional and global estimates.N2 O,NO and CH4 emissions from subtropical conventional vegetable systems were simultaneously measured at two different sites with hilly topography in the Sichuan basin,southwest China by using the static chamber gas chromatography technique.Results showed that annual soil N₂O and NO fluxes for the treatment receiving N fertilizer ranged from 6.34-7.71 kg N ha^-1 yr^-1 and 0.69-0.85 kg N ha^-1 yr^-1,respectively,while decreased soil CH4 uptakes by 26.4%as compared with no N fertilizer addition across our two sites of experiment.Overall,the average direct N2 O and NO emission factor(EFd)were 0.71%and 0.12%,respectively,which were both lower than the available EFd for subtropical conventional vegetable systems.This finding indicates that current regional and global estimates of N₂O and NO emissions from vegetable fields are likely overestimated.Background N₂O emissions(3.42-3.62 kg N ha^-1 yr^-1)from the subtropical conventional vegetable systems were relatively high as compared with available field measurements worldwide,suggesting that background N₂O emissions cannot be ignored for regional estimate of N₂O emissions in subtropical region.Nevertheless,the significantly intra-and inter-annual variations in N₂O,CH₄ and NO emissions were also observed in the present study,which could be explained by temporal variations of environmental variables(i.e.soil temperature and moisture).The differences in N₂O and NO EFd and CH₄emissions between various vegetable systems in particular under subtropical conditions should be taken into account when compiling regional or global inventories and proposing mitigation practices.     

Difference in organic carbon contents and distributions in particle-size fractions between soil and sediment on the Southern Loess Plateau,China

The purpose of this study was to assess the effect of long-term cultivation and water erosion on the soil organic carbon （OC） in particle-size fractions. The study site is located at Nihegou Watershed in the Southern Loess Plateau, China. The soil at this site is loess with loose and silty structure, and contains macropores. The results showed that the OC concentrations in sediments and in the particle-size fractions of sediments were higher than those in soils and in the particle-size fractions of soils. The OC concentration was highest in the clay particles and was lowest in the sand particles. Clay particles possessed higher OC enrichment ability than silt and sand particles. The proportions of OC in the silt fractions of soil and sediment were the highest （mean value of 53.87% and 58.48%, respectively）, and the total proportion of OC in the clay and silt fractions accounted for 96% and 98% of the total OC in the soil and sediment, respectively. The loss of OC was highest in silt particles, with an average value of 0.16 Mg ha^-1 y^-1, and was lowest in the sand （0.003 Mg ha^-1 y^-l）. This result suggests that the fine particle-size fraction in the removed sediment may be an important indicator to assess soil OC losses.     

The impact of nitrogen amendment and crop growth on dissolved organic carbon in soil solution

Dissolved organic carbon (DOC) is an important component of the terrestrial carbon cycle. However, the sources and controlling factors of DOC in soils remain uncertain. In this study, the effects of nitrogen (N) amendment and crop growth on DOC in soil solution were examined at a maize-wheat rotated field located in the central Sichuan Basin in southwestern China. Nitrogen treatments in this study included 150 kg N ha^-1 season^-1, 200 kg N ha^-1 season^-1 and the control without any fertilizer application. During the whole experimental period, we observed significant decreases (p<0.05) in DOC concentrations in the sampled soil solutions associated with increase in N inputs at the bare soil plots, but no change in DOC at the plots with crop growth. The estimated average contributions of plantderived DOC were 16%, 24% and 32% of total DOC in the summer maize season and 21%, 32% and 38% in the winter wheat season along with the gradient of N fertilizer application rates. The results implied that the crop growth could play a key role in the soil DOC production, and the N input enhanced DOC production by increasing crop growth. The relationship between the DOC concentrations and the crop root biomass was statistically significant for both the maize and winter wheat seasons. Our observations indicated that crop growth exerted greater influence on the seasonal variability of DOC concentration in soil solutions at the experimental site, which overwhelmed the effect of soil native organic matter decomposition on DOC concentrations in soil solutions.     

Differences in tree species diversity and soil nutrient status in a tropical sacred forest ecosystem on Niyamgiri hill range, Eastern Ghats, India

We have quantitatively analyzed the tree species diversity with respect to soil nutrient status in three sites of a sacred forest ecosystem of Niyamgiri hill range,Eastern Ghats,India.Extensive field surveys and sampling were conducted in 3 sites of the hill range:Site 1 Pterocarpus dominated forest(PTF)(19°40’02.2" N and 83°21’23.1" E),Site 2 Mangifera dominated forest(MAF)(19°40’02.8" N and 83°21’40.8" E) and Site 3 Mixed forest(MIF)(19°36’47.1" N and 83°21’02.7" E).A total of 28 families,42 genera,46 tree species,and 286 individual trees were recorded on an area of 0.6 ha.Tree density varied between 470 and 490 individuals ha-1 and average basal area between 3.16 and 10.04 m2 ha-1.Shannon Index(H’) ranged from 2.34 to 4.53,Simpson’s Index ranged from 0.07 to 0.09,and equitability Index ranged from 0.7 to 1.34.The number of individuals was highest in the girth at breast height(GBH) class of 50-70 cm.The soil nutrient status of the three forest types was related to tree species diversity.The soil pH value of the three sites reflected the slightly acidic nature of the area.Species diversity was positively correlated with organic carbon and phosphorus and negatively with nitrogen,EC and pH.The results of the current study may be helpful to further develop a conservation planfor tree species in tropical sacred forest ecosystems.     

Preliminary study on limiting nutrients in seawater ponds

INrnODUCTIONTheaqUacultareindustryofChinaedsfirstintheworld-Fertilizationinfreshwatershasalonghistory,andiseffectivelyaPpliedforfishcultUre.Scholarsfromvchouscotm-trieshaveheenstudytngfertiliZationtheory,tecboqUeandaqUactiltUreecologyinfertilizedPOnds-SPecialattentionisgiventothetwncyandaPPlicationlevelwhenmantireisused,andtothekindandN:PraioOfchethecalfertilizersused(Boyd,l99o;li,I993;MoriartyandPullin,l987).Thedrpthecchacteristicsofphosphorus,andtheroleofureaappliedintoPOndswere…     

Crop residue incorporation and nitrogen fertilizer effects on greenhouse gas emissions from a subtropical rice system in Southwest China

Crop residue incorporation has been widely accepted as a way to increase soil carbon (C) sequestration and sustain soil fertility in agroecosystems. However, effect of crop residue incorporation on greenhouse gas (GHG) emissions in rice paddy soils remains uncertain. A field experiment was conducted to quantify emissions of CH₄ and N₂O and soil heterotrophic respiration (R_H) from a paddy rice field under five different crop residue treatments (i.e., 150 kg N ha^-1 of synthetic N fertilizer application only [NF], 150 kg N ha^-1 of synthetic N fertilizer plus 5.3 Mg ha^-1 wheat residue [NF-WR1], 150 kg N ha^-1 of synthetic N fertilizer plus 10.6 Mg ha^-1 wheat residue [NF-WR2], 75 kg N ha^-1 of synthetic N fertilizer plus 10.6 Mg ha^-1 wheat residue [50%NF-WR2] and 150 kg N ha^-1 of synthetic N fertilizer plus 21.2 Mg ha^-1 wheat residue [NF-WR3]) in southwest China. Our results showed that crop residue incorporation treatments (NF-WR1, NF-WR2, 50%NF-WR2, NF-WR3) significantly increased CH₄ emissions by at least 60%, but N₂O emissions were not enhanced and even suppressed by 25% in the NF-WR3 treatment as compared to the NF treatment. Soil R_H emissions were comparable among experimental treatments, while crop residue incorporation treatments significantly increased soil carbon sequestrations relative to the NF treatment. Overall, CH₄ emissions dominated total global warming potentials (GWP) across all experimental treatments. The average yieldscaled GWPs for the NF and NF-WR1 treatments were significantly lower than for the NF-WR2, 50%NFWR2 and NF-WR3 treatments. Given the comparable yield-scaled GWPs between the NF and NF-WR1 treatments, the NF-WR1 treatment could gain net carbon sequestration as compared with the NF treatment with net soil carbon loss. Our findings suggest that the NF-WR1 treatment should be an effective option to sustain rice production while mitigating GHG emissions from the rice field in China.     

Characterization of the growth,chlorophyll content and lipid accumulation in a marine microalgae Dunaliella tertiolecta under different nitrogen to phosphorus ratios

Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth,chlorophyll content and accumulation of lipids in Dunaliella tertiolecta,experiments were carried out in modified microalgal medium with inorganic nitrogen(nitrate-nitrogen) or organic nitrogen(urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1.The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate.Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures.It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium.The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios(p 0.05).The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D.tertiolecta.Conversely,higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus.The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D.tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.     

Uptake and recovery of soil nitrogen by bryophytes and vascular plants in an alpine meadow

Due to their particular physiology and life history traits, bryophytes are critical in regulating biogeochemical cycles and functions in alpine ecosystem. Hence, it is crucial to investigate their nutrient utilization strategies in comparison with vascular plants and understand their responses to the variation of growing season caused by climate change. Firstly, this study testified whether or not bryophytes can absorb nitrogen(N) directly from soil through spiking three chemical forms of 15N stable isotope tracer. Secondly, with stronger ability of carbohydrates assimilation and photosynthesis, it is supposed that N utilization efficiency of vascular plants is significantly higher than that of bryophytes. However, the recovery of soil N by bryophytes can still compete with vascular plants due to their greater phytomass. Thirdly, resource acquisition may be varied from the change of growing season, during which N pulse can be manipulated with 15N tracer addition at different time. Both of bryophytes and vascular plants contain more N in a longer growing season, and prefer inorganic over organic N. Bryophytes assimilate more NH4+ than NO3– and amino acid, which can be indicated from the greater shoot excess 15N of bryophytes. However, vascular plants prefer to absorb NO3– for their developed root systems and vascular tissue. Concerning the uptake of three forms N by bryophytes, there is significant difference between two manipulated lengths of growing season. Furthermore, the capacity of bryophytes to tolerate N-pollution may be lower than currently appreciated, which indicates the effect of climate change on asynchronous variation of soil N pools with plant requirements.     

Nitrogen Fertilizer Optimization and Cultivar Selection for Rice Grown near Mountainous Slopes in Orissa, India ——A Field Experiment and Simulation Model Study

Introduction Agriculture, which is the dominant sector in the mountains, is generally stagnant. Degradation of the natural resource base has contributed to an increase in frequency and intensity of landslides, gully formation, soil erosion, declining soil fertility, reduced per capita availability and fragmentation of land, and reduced flow of water for irrigation. This has led to steady decline in crop yields (5~30 %) or stagnation that caused food shortages at varying degrees among mountain …     

Nitrogen deposition and its spatial pattern in main forest ecosystems along north-south transect of eastern China

A continuous three-year observation(from May 2008 to April 2011)was conducted to characterize the spatial variation of dissolved inorganic nitrogen(DIN)deposition at eight main forest ecosystems along the north-south transect of eastern China(NSTEC).The results show that both throughfall DIN deposition and bulk DIN deposition increase from north to south along the NSTEC.Throughfall DIN deposition varies greatly from 2.7 kg N/(ha·yr)to 33.0 kg N/(ha·yr),with an average of 10.6 kg N/(ha·yr),and bulk DIN deposition ranges from 4.1 kg N/(ha·yr)to 25.4 kg N/(ha·yr),with an average of 9.8 kg N/(ha·yr).NH4+-N is the dominant form of DIN deposition at most sampling sites.Additionally,the spatial variation of DIN deposition is controlled mainly by precipitation.Moreover,in the northern part of the NSTEC,bulk DIN deposition is 17%higher than throughfall DIN deposition,whereas the trend is opposite in the southern part of the NSTEC.The results demonstrate that DIN deposition would likely threaten the forest ecosystems along the NSTEC,compared with the critical loads(CL)of N deposition,and DIN deposition in this region is mostly controlled by agricultural activities rather than industrial activities or transportation.     

Higher species diversity occurs in more fertile habitats without fertilizer disturbance in an alpine natural grassland community

Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands？ Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter （SOM）, total nitrogen （TN）, available nitrogen （AN）, total phosphorus （TP）, available phosphorus （AP）, and available potassium （AK） in the high alpine grasslands. Margalefs species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef＇s richness index. Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.     

Quantification of restricting factors of agricultural development in Min County of Gansu,China

Agricultural development in povertystricken areas is a major problem affecting agricultural modernization in China. This study discusses the restrictive factors affecting agricultural development in impoverished areas in China. A typical impoverished mountainous area, Min County,was selected for a case study. A regression analysis on the factors and characteristics of agricultural development in Min County between 1982 and 2017 was performed in this study. Taking agricultural output as the dependent variable, we selected nine main inputs of agricultural production in impoverished mountainous areas as the independent variables. Ridge regression analysis was carried out by testing for unit root and co-integration to verify the equilibrium relationship of the data. The results showed that the real Gross domestic product(GDP)per capita, the non-grain area ratio, the proportion of government expenditure on agriculture support to total expenditure, and the amount of chemical fertilizer applied in unit cultivated land area were the four most significant factors. The proportion of government expenditure on agriculture support to total expenditure was a negative influence, whereas the other three significant factors had a positive influence on agricultural output. This study highlights about the most significant factors affecting the agricultural development of impoverished mountainous regions in China.     

Spatial variability of soil carbon to nitrogen ratio and its driving factors in Ili River valley,Xinjiang, Northwest China

Soil carbon to nitrogen(C/N) ratio is one of the most important variables reflecting soil quality and ecological function,and an indicator for assessing carbon and nitrogen nutrition balance of soils.Its variation reflects the carbon and nitrogen cycling of soils.In order to explore the spatial variability of soil C/N ratio and its controlling factors of the Ili River valley in Xinjiang Uygur Autonomous Region,Northwest China,the traditional statistical methods,including correlation analysis,geostatistic alanalys and multiple regression analysis were used.The statistical results showed that the soil C/N ratio varied from 7.00 to 23.11,with a mean value of 10.92,and the coefficient of variation was 31.3%.Correlation analysis showed that longitude,altitude,precipitation,soil water,organic carbon,and total nitrogen were positively correlated with the soil C/N ratio(P 0.01),whereas negative correlations were found between the soil C/N ratio and latitude,temperature,soil bulk density and soil p H.Ordinary Cokriging interpolation showed that r and ME were 0.73 and 0.57,respectively,indicating that the prediction accuracy was high.The spatial autocorrelation of the soil C/N ratio was 6.4 km,and the nugget effect of the soil C/N ratio was 10% with a patchy distribution,in which the area with high value(12.00–20.41) accounted for 22.6% of the total area.Land uses changed the soil C/N ratio with the order of cultivated land grass land forest land garden.Multiple regression analysis showed that geographical and climatic factors,and soil physical and chemical properties could independently explain 26.8%and 55.4% of the spatial features of soil C/N ratio,while human activities could independently explain 5.4% of the spatial features only.The spatial distribution of soil C/N ratio in the study has important reference value for managing soil carbon and nitrogen,and for improving ecological function to similar regions.     

雷州半岛南部土壤肥力综合评价及空间变异

通过测定雷州半岛南部845个耕地土壤样品pH、有机质、全氮、有效磷、速效钾、碱解氮的含量,采用层次分析法确定各肥力评价指标权重,应用模糊数学法对该区域耕地土壤肥力进行综合评价,并利用ArcGIS 9.2软件对土壤肥力空间变异进行分析.结果表明:雷州半岛南部土壤有机质、全氮、有效磷、速效钾、碱解氮平均值分别为26.18 g/kg、1.48 g/kg 、34.63 mg/kg、158.57 mg/kg、133.17 mg/kg;土壤速效磷的变异系数最高,为103.14%,属强变异性,有机质、速效钾、碱解氮、全氮的变异系数属中等变异性,pH值的变异系数最小.土壤肥力总体水平处于中等偏低;从空间分布来看,土壤肥力中部高,东北、西南部相对较低     

Internal Loads and Bioavailability of Phosphorus and Nitrogen in Dianchi Lake,China

Sediments have a significant influence on the cycling of nutrient elements in lake environments. In order to assess the distribution characteristics and estimate the bioavailability of phosphorus and nitrogen in Dianchi Lake, organic and inorganic phosphorus and nitrogen forms were analysed. The 210 Pb radiometric dating method was employed to study temporal changes in the phosphorus and nitrogen pools in Dianchi Lake. The result show that the total phosphorus(TP) and total nitrogen(TN) were both at high concentrations, ranging from 697.5–3210.0 mg/kg and 1263.7–7155.2 mg/kg, respectively. Inorganic phosphorus(IP) and total organic nitrogen(TON) were the main constituents, at percentages of 59%–78% and 74%–95%, respectively, in the sediments. Spatially, there was a decreasing trend in phosphorus and nitrogen contents from the south and north to the lake centre, which is related to the distribution pattern of local economic production. The burial rates of the various phosphorus and nitrogen forms increased in same spatially and over time. Particularly in the past two decades, the burial rates doubled, with that TN reached to 1.287 mg/(cm~2·yr) in 2014. As the most reactive forms, nitrate nitrogen(NO_3-N) and ammonia nitrogen(NH_4-N) were buried more rapidly in the south region, implying that the potential for releasing sedimentary nitrogen increased from north to south. Based on their concentrations and burial rates, the internal loads of phosphorus and nitrogen were analysed for the last century. A TP pool of 71597.6 t and a TN pool of 81191.7 t were estimated for Dianchi Lake. Bioavailable phosphorus and nitrogen pools were also estimated at 44468.0 t and 5429.7 t, respectively, for the last century.     

Assessing Conservation Values of Forest Communities in Nanda Devi Biosphere Reserve: Plant Diversity,Species Distribution and Endemicity

Present study has been conducted in a biodiversity rich Nanda Devi Biosphere Reserve between 2000-3800 m in two different forest physiognomy holding sites to analyze the structure and composition of the forest communities including richness of native, non native and endemic species,and suggest conservation values at community and reserve level.A total of 60 sites were sampled and grouped in 11 and 8 communities for two representative sites Pindari-Sunderdhunga-Kafni(PSK) and Lata-Tolma-Phagti(LTP) respectively.From the sampled sites, 451 species(11.8%, 53 trees;17.71%, 80 shrubs; and 70.51%, 318 herbs) have been recorded.In general, PSK site represented 73.6% and LTP site represented only 54.9% of the total plant species recorded in the study area.Out of total species in PSK site, native species contributed 59.6%(198spp.) and 24.7% species were endemic and near endemic.In LTP site, 66.5% species were Himalayan natives and 33.5% were endemic and near endemic.The species richness ranged from 4-23 ind ha-1(tree),3-18 ind ha-1(sapling), 5-19 ind ha-1(seedling) in PSK site and 4-18 ind ha-1(tree), 4-11 ind ha-1(sapling), 4-16 ind ha-1(seedling) in LTP site.The density ranged from 260-535 ind ha-1(tree), 145-633 ind ha-1(sapling), 1450-8170 ind ha-1(seedling) in PSK site and 599-1211 ind ha-1(tree), 70-951 ind ha-1(sapling),470-1665 ind ha-1(seedling) in LTP site.Species diversity for trees ranged from 0.73-3.37, saplings,0.64-2.67, seedlings, 0.70-2.51, shrubs, 1-2.34 and herbs, 2.02-3.21 in PSK site and 0.63-1.61, saplings,0.76-1.36, seedlings, 0.35-1.79, shrubs, 0.98-2.73 and herbs, 2.48-3.61 in LTP site.These recorded values were almost comparable with the studies conducted in sub-tropical, temperate and sub-alpine regions of the west Himalaya.In some cases the values were slightly higher than the reported values.The important communities with high conservation values have been identified based on different ecological parameters and species distribution.Among all the prioritized communities, Mixed Silver firRhododendron-Maple community in PSK site and Taxus wallichana- A.pindrow mixed community in LTP site supports maximum richness and density of native and endemic species.This study calls for development of adequate strategy and action plan for the conservation and management of habitats, species,and communities under changing climate and socioeconomic scenarios, so that sustainable utilization of the species could be ensured.     

Characteristics of diffuse pollution of nitrogen and phosphorous from a small town in the hilly area of the central Sichuan Basin,China

Hydrological and hydro-chemical monitoring of nitrogen (N) and phosphorus (P) in a small urbanized catchment was conducted in the hilly area of the central Sichuan Basin, China, from 2010 through 2011. The diffuse N and P loadings in different forms of total nitrogen (TN) and phosphorus (TP), dissolved nitrogen (DN) and phosphorus (DP), as well as particulate nitrogen (PN) and phosphorus (PP) were calculated based on runoff discharges and chemical analyses. The results revealed that the diffuse pollution concentrations of TN, DN, PN, TP, DP and PP exhibited large variations during rainfall events, with peak concentrations occurring during the initial period. For all of the measured parameters, the event mean concentrations (EMCs) were observed to clearly vary among rainfall events. The EMCs of TN, DN, PN, TP, DP and PP (for all of the observed rainfall events) were 10.04, 6.62, 3.42, 1.30, 0.47 and 0.83 mg/L, respectively. The losses of diffuse N and P exhibited clear seasonal patterns and mainly occurred during the period from July through September, when the losses totaled 99.3 and 9.6 kg/ha for TN and TP, respectively, accounting for 75% and 74% of the total annual loadings. The mean annual loadings of TN and TP were 124.6 and 12.9 kg/ha, respectively. The results indicate that residential areas in the hilly area of the central Sichuan Basin are subject to high diffuse N and P loadings, posing a serious risk to the receiving water quality. Ecological buffering belts are recommended to incorporate into the urbanized catchment to reduce diffuse pollution.     

Studies on the effects of polyaspartate protease fertilizer enhancer in the absorptions of soil nutrition and the enzymatic activities of crops

1　Introduction　Chinaisboththelargestproducerandthelargestconsumerofchemicalfertilizersintheworld .Since1984 ,Chineseconsumptionofchemicalfertilizerhasincreasedmorethanonetimes ,fromabout 17millionmetrictonsto 35millionmetrictons .However ,dur ingthesameperiod ,theyieldoffoodproductionhasincreasedonlyabout 10 % .Thediscrepancybetweenfertilizerconsumptionandyieldincreasehasindicatedthedrasticdecreaseofthebenefitsofchemicalfertiliz ers .Infact ,theutilizationefficiencyofnitrogenfer tilizerinC…