2015 No. 2
Display Method:
2015, (2): 1-8.
doi: 10.3969/j.issn.1000-5641.2015.02.001
Abstract:
The coupling of sulfur and iron with nitrogen and phosphorus are intertwined to regulate the release of endogenous pollution from polluted river sediments. This paper summarized the environment behavior of blackening and odorcausing elements of sulfur and iron with key nutrients of nitrogen and phosphorus as well as the latest research progress on their coupling mechanisms. It also emphasized the great significance of exploring the coupling progress of sulfur and iron with nitrogen and phosphorus for solving the tough problem of reducing the nitrogen and phosphorus levels below national consent standards in treating malodorous rivers.
The coupling of sulfur and iron with nitrogen and phosphorus are intertwined to regulate the release of endogenous pollution from polluted river sediments. This paper summarized the environment behavior of blackening and odorcausing elements of sulfur and iron with key nutrients of nitrogen and phosphorus as well as the latest research progress on their coupling mechanisms. It also emphasized the great significance of exploring the coupling progress of sulfur and iron with nitrogen and phosphorus for solving the tough problem of reducing the nitrogen and phosphorus levels below national consent standards in treating malodorous rivers.
2015, (2): 9-20.
doi: 10.3969/j.issn.1000-5641.2015.02.002
Abstract:
In this paper, the eutrophication secondary disasters in urban malodorousback river were reviewed from the forming and treatment of malodorousback, and the disaster forms and control and preventive measures. The results indicated that with the implementation of many treatment projects, technologies and measures in pollution control and remediation, pollution load of urban malodorousback river was greatly reduced, water quality had been much improved, and the malodorousback disappeared gradually. All these resulted to the nutrient that can be utilized by plant was at high level, and the damaged ecosystem of urban river was restored and constructed. Once those environmental factors were very suitable, the major outbreak of eutrophication secondary disasters (e.g. algal bloom, Lemna minor L, Eichhorniacrassipes.) could be unavoidable. For its part, the control and preventive measures of eutrophication secondary disasters must be based on the treatment and remediation of malodorousback. In addition, we realized that the outbreak of eutrophication secondary disasters would be an unavoidable stage of the treatment and remediation of malodorousback, and the current focus on pollution control and remediation of urban river should be changed from the severe pollution treatment (e.g. malodorousback) to the nutrient (Nitrogen, phosphorus, etc.) control.
In this paper, the eutrophication secondary disasters in urban malodorousback river were reviewed from the forming and treatment of malodorousback, and the disaster forms and control and preventive measures. The results indicated that with the implementation of many treatment projects, technologies and measures in pollution control and remediation, pollution load of urban malodorousback river was greatly reduced, water quality had been much improved, and the malodorousback disappeared gradually. All these resulted to the nutrient that can be utilized by plant was at high level, and the damaged ecosystem of urban river was restored and constructed. Once those environmental factors were very suitable, the major outbreak of eutrophication secondary disasters (e.g. algal bloom, Lemna minor L, Eichhorniacrassipes.) could be unavoidable. For its part, the control and preventive measures of eutrophication secondary disasters must be based on the treatment and remediation of malodorousback. In addition, we realized that the outbreak of eutrophication secondary disasters would be an unavoidable stage of the treatment and remediation of malodorousback, and the current focus on pollution control and remediation of urban river should be changed from the severe pollution treatment (e.g. malodorousback) to the nutrient (Nitrogen, phosphorus, etc.) control.
2015, (2): 21-29.
doi: 10.3969/j.issn.1000-5641.2015.02.003
Abstract:
The data of land utilization and landscape diversity within mosquito monitoring point buffers in summer of 20072008 in Shanghai were extracted by remote sensing and geographic information system. In order to provide a reference basis for prevention and control of anophelism during the process of urbanization, the effect of variation and characteristic of spatial distribution of water and vegetation on mosquito density fluctuation were analyzed. The results showed that there was a positive relationship between mosquito density and landscape diversity, density of water network and vegetation, while negative relationship with degree of landscape fragmentation. It was conducive to mosquito breeding when the degree of vegetation coverage was 50%~70% in the study districts. The mosquito density of water and water conservancy facilities was larger than other types of land use and the mosquito density of suburb exceeded downtown of Shanghai in summer of 20072008. Therefore, the urban construction would influence the mosquito density significantly.
The data of land utilization and landscape diversity within mosquito monitoring point buffers in summer of 20072008 in Shanghai were extracted by remote sensing and geographic information system. In order to provide a reference basis for prevention and control of anophelism during the process of urbanization, the effect of variation and characteristic of spatial distribution of water and vegetation on mosquito density fluctuation were analyzed. The results showed that there was a positive relationship between mosquito density and landscape diversity, density of water network and vegetation, while negative relationship with degree of landscape fragmentation. It was conducive to mosquito breeding when the degree of vegetation coverage was 50%~70% in the study districts. The mosquito density of water and water conservancy facilities was larger than other types of land use and the mosquito density of suburb exceeded downtown of Shanghai in summer of 20072008. Therefore, the urban construction would influence the mosquito density significantly.
2015, (2): 30-39.
doi: 10.3969/j.issn.1000-5641.2015.02.004
Abstract:
The parameters of water quality such as pH, WT, DO, SD, NH4+-N,TN,DP,TP,CODCr,CODMn,BOD5,TOC和Chl-a were chosen as primary assessment factors to evaluate the water quality of six medium and small creeks in Shanghai by principal component analysis, comprehensive pollution index, comprehensive nutritive index, organic pollution index and comprehensive water quality identification index from Match 2013 to February 2014. The evaluation methods were compared, and pollution sources of creeks were also analyzed. Results showed that great spatial difference was obtained among the water qualities of six creeks. The water quality of Danjiang creek was the worst, followed by Gongye creek, and that of Liwa creek was the best. TN and TP were the main primary pollution factors. The major form of total phosphorus in the six creeks was existed as dissolved phosphorus. The main form of nitrogen in creeks of Gongye, Changbang, Zhenru and Danjiang was of ammonia nitrogen. However, nitrate nitrogen was considered as the main form of nitrogen in creeks of Yingtao and Liwa.
The parameters of water quality such as pH, WT, DO, SD, NH4+-N,TN,DP,TP,CODCr,CODMn,BOD5,TOC和Chl-a were chosen as primary assessment factors to evaluate the water quality of six medium and small creeks in Shanghai by principal component analysis, comprehensive pollution index, comprehensive nutritive index, organic pollution index and comprehensive water quality identification index from Match 2013 to February 2014. The evaluation methods were compared, and pollution sources of creeks were also analyzed. Results showed that great spatial difference was obtained among the water qualities of six creeks. The water quality of Danjiang creek was the worst, followed by Gongye creek, and that of Liwa creek was the best. TN and TP were the main primary pollution factors. The major form of total phosphorus in the six creeks was existed as dissolved phosphorus. The main form of nitrogen in creeks of Gongye, Changbang, Zhenru and Danjiang was of ammonia nitrogen. However, nitrate nitrogen was considered as the main form of nitrogen in creeks of Yingtao and Liwa.
2015, (2): 40-47.
doi: 10.3969/j.issn.1000-5641.2015.02.005
Abstract:
Hydrological Simulation ProgramFortran (HSPF) is a comprehensively semidistributed hydrological model and can simulate hydrological conditions and water quality accurately in watersheds. It has been extensively applied in the fields of water resources and environment. The article reviewed the model mechanism of hydrology,sediment erosion and migration of pollutants, and summarized the latest devolepments in the modeling of the runoff, the migration of pollutants,the influence of land use or land cover change and climate change on watersheds. Besides, the research directions of complete the model were discussed, including the migration mechanism of pollutant, the uncertainty of model parameters and the combination with other models.
Hydrological Simulation ProgramFortran (HSPF) is a comprehensively semidistributed hydrological model and can simulate hydrological conditions and water quality accurately in watersheds. It has been extensively applied in the fields of water resources and environment. The article reviewed the model mechanism of hydrology,sediment erosion and migration of pollutants, and summarized the latest devolepments in the modeling of the runoff, the migration of pollutants,the influence of land use or land cover change and climate change on watersheds. Besides, the research directions of complete the model were discussed, including the migration mechanism of pollutant, the uncertainty of model parameters and the combination with other models.
2015, (2): 48-57.
doi: 10.3969/j.issn.1000-5641.2015.02.006
Abstract:
In order to understand the effects of environment factors on phytoplankton growth, phytoplankton in Dishui Lake had been sampled at 14 monitoring spot locations in December of 2012 and April, July, November of 2013, respectively. The physical and chemical indicators had been monitored to analyze the growth of phytoplankton and the spacetime characteristics of influence factors. Correlative analysis was also made to determine major parameters that influence the growth of phytoplankton in Dishui Lake. It showed that main diversion channel of Dishui Lake is much higher than that of other sites. Seasonal variety of phytoplankton density was similar to that of chlorophylla content, but phytoplankton density of summer was a little higher than that of winter. The effect of filter feeding fish on phytoplankton can explain this phenomenon. Correlation analysis indicated that total phosphorous concentration had great influence on the growth of phytoplankton. This study provides biological basement in evaluating water quality and prevents eutrophication of Dishui Lake.
In order to understand the effects of environment factors on phytoplankton growth, phytoplankton in Dishui Lake had been sampled at 14 monitoring spot locations in December of 2012 and April, July, November of 2013, respectively. The physical and chemical indicators had been monitored to analyze the growth of phytoplankton and the spacetime characteristics of influence factors. Correlative analysis was also made to determine major parameters that influence the growth of phytoplankton in Dishui Lake. It showed that main diversion channel of Dishui Lake is much higher than that of other sites. Seasonal variety of phytoplankton density was similar to that of chlorophylla content, but phytoplankton density of summer was a little higher than that of winter. The effect of filter feeding fish on phytoplankton can explain this phenomenon. Correlation analysis indicated that total phosphorous concentration had great influence on the growth of phytoplankton. This study provides biological basement in evaluating water quality and prevents eutrophication of Dishui Lake.
2015, (2): 58-66.
doi: 10.3969/j.issn.1000-5641.2015.02.007
Abstract:
The physicochemical factors, heavy metals and biological toxicity in water sample before, during and after dredging of Niuqiaodi River in Wenzhou were investigated. The result showed that after the sediment dredging of Niuqiaodi River, the CODCr concentration in water sample was significantly reduced, while the DO content and transparency were enhanced. The contents of NH+4-N, TN, TP and heavy metals in water sample were firstly increased and then decreased. Both the Luminescent bacteria and Xenopus tropicalis embryos tests indicated the toxicity of water sample firstly weakened, then enhanced in different stages of dredging. Generally speaking, sediment dredging was helpful to alleviate the toxicity of water sample. The correlation analysis showed the toxicity of water sample was significantly related to TN content and had little relationship with heavy metals.
The physicochemical factors, heavy metals and biological toxicity in water sample before, during and after dredging of Niuqiaodi River in Wenzhou were investigated. The result showed that after the sediment dredging of Niuqiaodi River, the CODCr concentration in water sample was significantly reduced, while the DO content and transparency were enhanced. The contents of NH+4-N, TN, TP and heavy metals in water sample were firstly increased and then decreased. Both the Luminescent bacteria and Xenopus tropicalis embryos tests indicated the toxicity of water sample firstly weakened, then enhanced in different stages of dredging. Generally speaking, sediment dredging was helpful to alleviate the toxicity of water sample. The correlation analysis showed the toxicity of water sample was significantly related to TN content and had little relationship with heavy metals.
2015, (2): 67-74.
doi: 10.3969/j.issn.1000-5641.2015.02.008
Abstract:
The physicochemical factors and heavy metals in sediment before, during and after dredging of Niuqiaodi River in Wenzhou were investigated. The result showed that after the sediment dredging of Niuqiaodi River, the contents of TP, TOC and heavy metal in sediment were firstly decreased and then increased. The heavy metal contents in sediment reached the lowest level in one to three months after dredging. The contents of the pollutants in the river were significantly reduced after sediment dredging, but the improvement of water quality and sediment only lasts three to nine months. The evaluation results of the geoaccumulation index (Igeo) and the potential ecological risk evaluation indicated the sediments of Niuqiaodi River were seriously polluted by heavy metals and the sediment dredging contributed to reduction of pollution levels of heavy metals in sediment.
The physicochemical factors and heavy metals in sediment before, during and after dredging of Niuqiaodi River in Wenzhou were investigated. The result showed that after the sediment dredging of Niuqiaodi River, the contents of TP, TOC and heavy metal in sediment were firstly decreased and then increased. The heavy metal contents in sediment reached the lowest level in one to three months after dredging. The contents of the pollutants in the river were significantly reduced after sediment dredging, but the improvement of water quality and sediment only lasts three to nine months. The evaluation results of the geoaccumulation index (Igeo) and the potential ecological risk evaluation indicated the sediments of Niuqiaodi River were seriously polluted by heavy metals and the sediment dredging contributed to reduction of pollution levels of heavy metals in sediment.
2015, (2): 75-83.
doi: 10.3969/j.issn.1000-5641.2015.02.009
Abstract:
The reclamation district of Lingkun Island in Wenzhou was taken as a study object in order to supply reference for rational planning of reclamation district, through determinations and risk assessments of heavy metal Cd、Cr、Cu、Zn、Mn、Ni、Pb、Hg and As in samples collected from six areas. The results showed the soils of reclamation district area were polluted by Cd and Hg,with the geoaccumulation index of Cd and Hg higher than that of other heavy metals, which contributed to the ecological risk of heavy metals in reclamation district. The contents of heavy metals in the soil of survey area were sediment reclamation district agricultural district other 4 districts. The Luminescent bacteria tests indicated the soils of sediment reclamation district belonged to medium toxicity, where the Xenopus tropicalis embryos hardly survived. Therefore, recovery methods of sediment reclamation district should be taken before the utilization and development.
The reclamation district of Lingkun Island in Wenzhou was taken as a study object in order to supply reference for rational planning of reclamation district, through determinations and risk assessments of heavy metal Cd、Cr、Cu、Zn、Mn、Ni、Pb、Hg and As in samples collected from six areas. The results showed the soils of reclamation district area were polluted by Cd and Hg,with the geoaccumulation index of Cd and Hg higher than that of other heavy metals, which contributed to the ecological risk of heavy metals in reclamation district. The contents of heavy metals in the soil of survey area were sediment reclamation district agricultural district other 4 districts. The Luminescent bacteria tests indicated the soils of sediment reclamation district belonged to medium toxicity, where the Xenopus tropicalis embryos hardly survived. Therefore, recovery methods of sediment reclamation district should be taken before the utilization and development.
2015, (2): 84-90.
doi: 10.3969/j.issn.1000-5641.2015.02.010
Abstract:
In this study, 16S rDNA based PCR amplification and denaturing gradientgel electrophoresis (PCRDGGE) as well as sequence alignment from the excised DGGE bands were used to investigate the bacterial diversity and variation. In addition, the redundancy analysis was adopted to assess the relationship between bacterial community structure and environmental factors. The results showed that aeration had marked effects on bacterial community structure in malodorous river sediments and different aeration intensities resulted in variable bacterial community. Amongst them the highest richness of bacterial community was observed with the aeration turbulence of Re=1 810 and DO of 7.35. It was also inferred that moderate aeration facilitated the growths of related bacteria to N and Scycling and theProteobacteria was dominant. It was also found that DO and Re played important roles in bacterial community from river sediments.
In this study, 16S rDNA based PCR amplification and denaturing gradientgel electrophoresis (PCRDGGE) as well as sequence alignment from the excised DGGE bands were used to investigate the bacterial diversity and variation. In addition, the redundancy analysis was adopted to assess the relationship between bacterial community structure and environmental factors. The results showed that aeration had marked effects on bacterial community structure in malodorous river sediments and different aeration intensities resulted in variable bacterial community. Amongst them the highest richness of bacterial community was observed with the aeration turbulence of Re=1 810 and DO of 7.35. It was also inferred that moderate aeration facilitated the growths of related bacteria to N and Scycling and theProteobacteria was dominant. It was also found that DO and Re played important roles in bacterial community from river sediments.
2015, (2): 91-97.
doi: 10.3969/j.issn.1000-5641.2015.02.011
Abstract:
The black odor problems in the urban river of current China are in need to be solved urgently. In recent years, the insuit polluted sediment remediation technology of nitrateinduced indigenous microbial promoting was focused among many researchers. However, attention on the key reaction of sulfur autotrophic denitrification (SAD) was comparatively rare. The application research situations of SAD in the field of environmental pollution control were firstly introduced in this paper. Then the characters, the course of SAD, the production and accumulation byproducts (N2O、NO-2) reaction in sediment were discussed, as well as the research progress in population ecology characters and the population ecological relation between NRSOB and SRB. In addition, the some scientific problems in these researches which are not clear now were pointed out in the text. Finally, it was proposed that the research work of the denitrification process and mechanism of molecular ecology on sulfur autotrophic denitrification in the blackodor river sediment were important to the development of black odor control research work in the river of China.
The black odor problems in the urban river of current China are in need to be solved urgently. In recent years, the insuit polluted sediment remediation technology of nitrateinduced indigenous microbial promoting was focused among many researchers. However, attention on the key reaction of sulfur autotrophic denitrification (SAD) was comparatively rare. The application research situations of SAD in the field of environmental pollution control were firstly introduced in this paper. Then the characters, the course of SAD, the production and accumulation byproducts (N2O、NO-2) reaction in sediment were discussed, as well as the research progress in population ecology characters and the population ecological relation between NRSOB and SRB. In addition, the some scientific problems in these researches which are not clear now were pointed out in the text. Finally, it was proposed that the research work of the denitrification process and mechanism of molecular ecology on sulfur autotrophic denitrification in the blackodor river sediment were important to the development of black odor control research work in the river of China.
Bioassay for toxicity of water and sediment in Longhong Ravine and Beili Lake in West Lake, Hangzhou
2015, (2): 98-105.
doi: 10.3969/j.issn.1000-5641.2015.02.012
Abstract:
Using Vibrio Qinghaiensi, Caenorhabditis elegans and Xenopus tropicalis embryos, the potential toxicity of Longhong Ravine and Beili Lake were respectively detected. Results showed that water and sediments from Longhong Ravine and Beili Lake were not toxic to the three organisms. On the contrary, some samples showed positive effects, for example, enhanced luminous intensity 〖JP〗of Vibrio Qinghaiensis and promoted the growth of Xenopus tropicalis embryos. A small number of samples caused slight teratogenic effects on Xenopus embryos, which were likely related to accidental discharges of pollutants. Our results suggested that Longhong Ravine and Beili Lake present relatively low ecological risks, which indicated high biological safety in West Lake.
Using Vibrio Qinghaiensi, Caenorhabditis elegans and Xenopus tropicalis embryos, the potential toxicity of Longhong Ravine and Beili Lake were respectively detected. Results showed that water and sediments from Longhong Ravine and Beili Lake were not toxic to the three organisms. On the contrary, some samples showed positive effects, for example, enhanced luminous intensity 〖JP〗of Vibrio Qinghaiensis and promoted the growth of Xenopus tropicalis embryos. A small number of samples caused slight teratogenic effects on Xenopus embryos, which were likely related to accidental discharges of pollutants. Our results suggested that Longhong Ravine and Beili Lake present relatively low ecological risks, which indicated high biological safety in West Lake.
2015, (2): 106-112.
doi: 10.3969/j.issn.1000-5641.2015.02.013
Abstract:
Using a model of C.elegans, this study aims to investigate the effect of PFOS on the lifespan and its mechanisms. Results showed that 0.2~200 mol/L PFOS shortened the lifespan of wild type wormsin a concentrationdependent manner after 50 h exposure.In four transgenic strains, mutation of daf-16, daf-2 and age-1 which are related to Insulin/IGFl.1pathway(IIS), could affect the lifespans of nematodes. We further observed lifespan change rates of the four transgene C.elegansafter exposed to PFOS.Results showed that mutation of daf-16 or daf-2 did not alter PFOS induced effects of shortening lifespan in CF1139 and CF1580 strain.However, knockout of daf-16b or mutation of age-1blocked PFOS induced effects of shortening lifespan in CF1295 and TJ1052 strain. Our results suggested that PFOS could accelerate aging and shorten the lifespan of nematodes. PFOSinduced effects are closely relative with IIS signaling pathways, in which daf-16b and age-1 play important roles.
Using a model of C.elegans, this study aims to investigate the effect of PFOS on the lifespan and its mechanisms. Results showed that 0.2~200 mol/L PFOS shortened the lifespan of wild type wormsin a concentrationdependent manner after 50 h exposure.In four transgenic strains, mutation of daf-16, daf-2 and age-1 which are related to Insulin/IGFl.1pathway(IIS), could affect the lifespans of nematodes. We further observed lifespan change rates of the four transgene C.elegansafter exposed to PFOS.Results showed that mutation of daf-16 or daf-2 did not alter PFOS induced effects of shortening lifespan in CF1139 and CF1580 strain.However, knockout of daf-16b or mutation of age-1blocked PFOS induced effects of shortening lifespan in CF1295 and TJ1052 strain. Our results suggested that PFOS could accelerate aging and shorten the lifespan of nematodes. PFOSinduced effects are closely relative with IIS signaling pathways, in which daf-16b and age-1 play important roles.
2015, (2): 113-121.
doi: 10.3969/j.issn.1000-5641.2015.02.014
Abstract:
In order to compare the differences of gas exchange between suntolerant and shadetolerant plants, diurnal variations in photosynthetic and transpiration indices were measured using LI6400 portable photosynthesis system in two endangered species, Ostrya rehderiana Chun (suntolerance) and Acer yangjuechi Fang et P. L. Chiu (shadetolerance). Our results showed that O. rehderiana was a bimodal curve in diurnal change of photosynthesis rate (Pn), while A. yangjuechi was a unimodal curve. A. yangjuechi had a higher light use efficiency (RUE) than O. rehderiana under a relatively weak light (p0.05), suggesting A. yangjuechi had an increased net photosynthesis rate (P n) in weaker light conditions, e.g. under a longterm shade circumstance. The water use efficiency (WUE) was also higher in A. yangjuechi than in O. rehderiana (p0.05). This indicated A. yangjuechi had a lower transpiration in shaded conditions.
In order to compare the differences of gas exchange between suntolerant and shadetolerant plants, diurnal variations in photosynthetic and transpiration indices were measured using LI6400 portable photosynthesis system in two endangered species, Ostrya rehderiana Chun (suntolerance) and Acer yangjuechi Fang et P. L. Chiu (shadetolerance). Our results showed that O. rehderiana was a bimodal curve in diurnal change of photosynthesis rate (Pn), while A. yangjuechi was a unimodal curve. A. yangjuechi had a higher light use efficiency (RUE) than O. rehderiana under a relatively weak light (p0.05), suggesting A. yangjuechi had an increased net photosynthesis rate (P n) in weaker light conditions, e.g. under a longterm shade circumstance. The water use efficiency (WUE) was also higher in A. yangjuechi than in O. rehderiana (p0.05). This indicated A. yangjuechi had a lower transpiration in shaded conditions.
2015, (2): 122-132.
doi: 10.3969/j.issn.1000-5641.2015.02.015
Abstract:
To reveal the character of seed rain of species with different dispersal modes, we explored the seed rain in a 20 hm2 evergreen broadleaved forest dynamic plot in Tiantong from Oct.2012 to Sept.2013, then analyzed the density and species composition of seed rain and seed limitation (measured by the proportion of plots that seeds were not dispersed in). The results were showed as follows: (1) A total of 13,638 seeds were collected belonging to 66 species and 28 families.The density of seed rain was 146 seeds/m2during the twelvemonth period (total trap area = 93.5 m2); (2) 56% of tree species were not found in seed traps which contributed to generally low species similarity between seeds and adult plants. Different dispersal modes also affected the Jaccard similarity coefficient (R). The extreme R coefficient(Rmax) while the maximum distance from the seed collector (d) were caused by wind(Anemochory:Rmax=0.226,d=20 m;Gravity:Rmax=0.077,d=9 m;Zoochory:Rmax=0.094,d=13 m), which indicated that the seeds 〖JP2〗dispersed by wind had an advantage in longdistance dispersal;(3)More than 60% of species were distributed among no more than ten seed traps during a year, which exhibited seed limitation in plot. As far as the relatively dominant species(IV1) were concerned, dispersal mode could have a great impact on seed limitation. When it comes to anemochory species, it was possible that their seed limitation was just the result of lacking in individuals, and a severe seed limitation in gravity and zoochory species could be attributed to low productivity and incapacity in dispersal.
To reveal the character of seed rain of species with different dispersal modes, we explored the seed rain in a 20 hm2 evergreen broadleaved forest dynamic plot in Tiantong from Oct.2012 to Sept.2013, then analyzed the density and species composition of seed rain and seed limitation (measured by the proportion of plots that seeds were not dispersed in). The results were showed as follows: (1) A total of 13,638 seeds were collected belonging to 66 species and 28 families.The density of seed rain was 146 seeds/m2during the twelvemonth period (total trap area = 93.5 m2); (2) 56% of tree species were not found in seed traps which contributed to generally low species similarity between seeds and adult plants. Different dispersal modes also affected the Jaccard similarity coefficient (R). The extreme R coefficient(Rmax) while the maximum distance from the seed collector (d) were caused by wind(Anemochory:Rmax=0.226,d=20 m;Gravity:Rmax=0.077,d=9 m;Zoochory:Rmax=0.094,d=13 m), which indicated that the seeds 〖JP2〗dispersed by wind had an advantage in longdistance dispersal;(3)More than 60% of species were distributed among no more than ten seed traps during a year, which exhibited seed limitation in plot. As far as the relatively dominant species(IV1) were concerned, dispersal mode could have a great impact on seed limitation. When it comes to anemochory species, it was possible that their seed limitation was just the result of lacking in individuals, and a severe seed limitation in gravity and zoochory species could be attributed to low productivity and incapacity in dispersal.
2015, (2)
doi: 10.3969/j.issn.1000-5641.2015.02.016
Abstract:
Leaf mass based nitrogen (Nmass) and phosphorus (Pmass) concentrate were measured for three annual weeds,Setaria viridis, Echinochloa crusgalli and Eclipta prostrate which are widely distributed from urban areas to rural areas in Shanghai. The differences of Nmass and Pmassamong three urban gradients were compared for each species and were related with the total nitrogen (SoilN) and phosphourous (SoilP) concentrate in soil. The results indicated that: ① N mass of all annual weeds was significantly increased from urban areas to rural areas, but Pmass did not show significant variation. ② For each species, S. viridis and E.prostrate showed a significant increasing tendency of Nmass from urban areas to rural areas, while only S. viridis showed a significant increasing tendency of Pmass. ③ Both of SoilN and SoilP showed negative relationships with Nmass and Pmass. All those results suggested that annual weed could response to urbanization by changing nitrogen and phosphorous concentrate in leaves which might be partly caused by the variation of soil fertility, but species have different strategies in changing Nmassand Pmass to adapt the urban habitats.
Leaf mass based nitrogen (Nmass) and phosphorus (Pmass) concentrate were measured for three annual weeds,Setaria viridis, Echinochloa crusgalli and Eclipta prostrate which are widely distributed from urban areas to rural areas in Shanghai. The differences of Nmass and Pmassamong three urban gradients were compared for each species and were related with the total nitrogen (SoilN) and phosphourous (SoilP) concentrate in soil. The results indicated that: ① N mass of all annual weeds was significantly increased from urban areas to rural areas, but Pmass did not show significant variation. ② For each species, S. viridis and E.prostrate showed a significant increasing tendency of Nmass from urban areas to rural areas, while only S. viridis showed a significant increasing tendency of Pmass. ③ Both of SoilN and SoilP showed negative relationships with Nmass and Pmass. All those results suggested that annual weed could response to urbanization by changing nitrogen and phosphorous concentrate in leaves which might be partly caused by the variation of soil fertility, but species have different strategies in changing Nmassand Pmass to adapt the urban habitats.