Distribution characteristics of soil organic matter（SOM） and total nitrogen（TN） were studied in different plant communities of the Yajiageng vertical belt in Gongga Mountain around the Dadu River banks. The result...Distribution characteristics of soil organic matter（SOM） and total nitrogen（TN） were studied in different plant communities of the Yajiageng vertical belt in Gongga Mountain around the Dadu River banks. The results show： （1） the contents of SOM and TN of the plant communities gradually decreased with the following order： subalpine coniferous forest （3 027 m）, subalpine meadow （3 873 m）, coniferous broadleaved mixed forest（2 737 m）, subalpine shrub（3 565 m） and treeline（3 564 m）. （2） With soil profile depth increasing, the contents of SOM and TN gradually decreased. For different vegetation types, the contents of SOM and TN in sub-alpine coniferous forest were higher than that of other vegetational types. （3）The ratio of the content of carbon to the content of total nitrogen （Cc/CTN）WaS 13.5-27.6, which was relatively lower than the appropriate Cc/CTN of 25-30, and indicated that the soil in favor of the organic matter decomposed and nutrients released. Cc/CTN in the soil had no correlation with sea level altitude. However, its distribution in the soil x, aried with different vegetation types. （4） Nitrogen in SOM existed mainly in the form of organic nitrogen, and Cc/CTN in the soil was not obvious correlated with SOM and TN.展开更多
Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content i...Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.展开更多
Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus...Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determinationmethods presently. The compounds used for the phosphorus recovery test were categorized into three groups accordingto their chemical structure. It was found that low power UV irradiation can decompose POC or PC bonds efficientlybut may be inefficient for POP bonds. Heating-bath in acid condition is useful for decomposing POP bonds. Usingthe continuous flow analysis system (Auto-analyzer II), UV digestion and heating-bath, series experiments were carriedout based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and thefactors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flowanalysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of33%~51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decompositionefficiency for dissolved phosphorus based on the continuous flow analysis system.展开更多
Soil carbon and nutrient contents and their importance in advancing our understanding of biogeochemical cycling in terrestrial ecosystem, has motivated ecologists to find their spatial patterns in various geographical...Soil carbon and nutrient contents and their importance in advancing our understanding of biogeochemical cycling in terrestrial ecosystem, has motivated ecologists to find their spatial patterns in various geographical area. Few studies have focused on changes in the physical and chemical properties of soils at high altitudes. Our aim was to identify the spatial distribution of soil physical and chemical properties in cold and arid climatic region. We also tried to explore relationship between soil organic carbon （SOC） and total nitrogen （TN）, total phosphorus （TP）, available nitrogen （AN）, available phosphorus （AP）, soil particle size distribution （PSD）. Samples were collected at 44 sites along a 300 km transect across the alpine grassland of northern Tibet. The study results showed that grassland type was the main factor influencing SOC, TN and TP distribution along the Gangdise Mountain-Shenzha-Shuanghu Transect. SOC, TN and TP contents were significantly higher in alpine meadow than alpine steppe ecosystems. SOC, TN, TP and AN contents in two soil layers （0-15 cm and 15-3o cm） showed no significant differences, while AP content in top soft （0-15 cm） was significantly higher than that in sub-top soil （15-30cm）. SOC content was correlated positively with TN and TP content （r = 0.901and 0.510, respectively）. No correlations were detected for clay content and fractal dimension of particle size distribution （D）. Our study results indicated the effects of vegetation on soil C, N and P seem to be more important than that of rocks itself along latitude gradient on the northern Tibetan Plateau. However, we did not found similar impacts of vegetation on soil properties in depth. Inaddition, this study also provided an interesting contribution to the global data pool on soil carbon stocks.展开更多
Three equal field plots were cultivated with respectively wheat, field pea and faba bean. The common conventional production technology, including the use of chemical fertilizers was applied in wheat, but no fertilize...Three equal field plots were cultivated with respectively wheat, field pea and faba bean. The common conventional production technology, including the use of chemical fertilizers was applied in wheat, but no fertilizers at all were used in faba bean and field pea plots. Atter legume harvesting, forty day old broccoli and cauliflower seedlings were transplanted to each of them according to three replications randomized block design. The transplanting was conducted at equal planting density, and common organic production practices were applied in entire production cycle. The legume crops improved soil fertility by increasing total soil N （Nitrogen） and improving P （Phosphorus） and K （Potassium） availability to the subsequent crops. As a result, an enhanced vegetative growth, improved curd setting and increased average curd weight was found in broccoli and cauliflower. However, there were significant differences between legume crops themselves regarding the proved benefits to the subsequent crops, confirming a clear advantage of faba bean versus field pea. A significantly higher above ground biomass was recorded in cauliflower plants followed faba bean, compared with field pea and wheat, but no difference was found regarding the biomass production in broccoli. The higher percentage of plants set curds （either broccoli or cauliflower） was obtained in the variants followed faba bean and then field pea. The same was true regarding total curd yield and the average curd weight for both： broccoli and cauliflower.展开更多
Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of d...Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.展开更多
基金the National Basic Research Program of China (973 Program) (2005CB422005)
文摘Distribution characteristics of soil organic matter（SOM） and total nitrogen（TN） were studied in different plant communities of the Yajiageng vertical belt in Gongga Mountain around the Dadu River banks. The results show： （1） the contents of SOM and TN of the plant communities gradually decreased with the following order： subalpine coniferous forest （3 027 m）, subalpine meadow （3 873 m）, coniferous broadleaved mixed forest（2 737 m）, subalpine shrub（3 565 m） and treeline（3 564 m）. （2） With soil profile depth increasing, the contents of SOM and TN gradually decreased. For different vegetation types, the contents of SOM and TN in sub-alpine coniferous forest were higher than that of other vegetational types. （3）The ratio of the content of carbon to the content of total nitrogen （Cc/CTN）WaS 13.5-27.6, which was relatively lower than the appropriate Cc/CTN of 25-30, and indicated that the soil in favor of the organic matter decomposed and nutrients released. Cc/CTN in the soil had no correlation with sea level altitude. However, its distribution in the soil x, aried with different vegetation types. （4） Nitrogen in SOM existed mainly in the form of organic nitrogen, and Cc/CTN in the soil was not obvious correlated with SOM and TN.
基金国家重点基础研究发展计划(973计划)，国家自然科学基金，The Science Foundation of the State Key Laboratory of Soil Erosion and Dry Farming, CAS
文摘Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.
基金The research was supported by the National Basic Research Program(“973”Program)of China under contract No.2002CB412405the Key Science and Technology Plan of the Ministry of Education of China under contract No.[2000]156-00079the Joint Sino-German Project under contract No.03F0189A.
文摘Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determinationmethods presently. The compounds used for the phosphorus recovery test were categorized into three groups accordingto their chemical structure. It was found that low power UV irradiation can decompose POC or PC bonds efficientlybut may be inefficient for POP bonds. Heating-bath in acid condition is useful for decomposing POP bonds. Usingthe continuous flow analysis system (Auto-analyzer II), UV digestion and heating-bath, series experiments were carriedout based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and thefactors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flowanalysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of33%~51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decompositionefficiency for dissolved phosphorus based on the continuous flow analysis system.
基金supported by the Western Action Plan Project of the Chinese Academy of Sciences(Grant No.KZCX2-XB3-08)the Strategic Pilot Science and Technology Projects of Chinese Academy of Sciences(Grant No.XDB03030505)the One Hundred Young Persons Project of the Institute of Mountain Hazards and Environment(Grant No.SDSQB-2010-02)
文摘Soil carbon and nutrient contents and their importance in advancing our understanding of biogeochemical cycling in terrestrial ecosystem, has motivated ecologists to find their spatial patterns in various geographical area. Few studies have focused on changes in the physical and chemical properties of soils at high altitudes. Our aim was to identify the spatial distribution of soil physical and chemical properties in cold and arid climatic region. We also tried to explore relationship between soil organic carbon （SOC） and total nitrogen （TN）, total phosphorus （TP）, available nitrogen （AN）, available phosphorus （AP）, soil particle size distribution （PSD）. Samples were collected at 44 sites along a 300 km transect across the alpine grassland of northern Tibet. The study results showed that grassland type was the main factor influencing SOC, TN and TP distribution along the Gangdise Mountain-Shenzha-Shuanghu Transect. SOC, TN and TP contents were significantly higher in alpine meadow than alpine steppe ecosystems. SOC, TN, TP and AN contents in two soil layers （0-15 cm and 15-3o cm） showed no significant differences, while AP content in top soft （0-15 cm） was significantly higher than that in sub-top soil （15-30cm）. SOC content was correlated positively with TN and TP content （r = 0.901and 0.510, respectively）. No correlations were detected for clay content and fractal dimension of particle size distribution （D）. Our study results indicated the effects of vegetation on soil C, N and P seem to be more important than that of rocks itself along latitude gradient on the northern Tibetan Plateau. However, we did not found similar impacts of vegetation on soil properties in depth. Inaddition, this study also provided an interesting contribution to the global data pool on soil carbon stocks.
文摘Three equal field plots were cultivated with respectively wheat, field pea and faba bean. The common conventional production technology, including the use of chemical fertilizers was applied in wheat, but no fertilizers at all were used in faba bean and field pea plots. Atter legume harvesting, forty day old broccoli and cauliflower seedlings were transplanted to each of them according to three replications randomized block design. The transplanting was conducted at equal planting density, and common organic production practices were applied in entire production cycle. The legume crops improved soil fertility by increasing total soil N （Nitrogen） and improving P （Phosphorus） and K （Potassium） availability to the subsequent crops. As a result, an enhanced vegetative growth, improved curd setting and increased average curd weight was found in broccoli and cauliflower. However, there were significant differences between legume crops themselves regarding the proved benefits to the subsequent crops, confirming a clear advantage of faba bean versus field pea. A significantly higher above ground biomass was recorded in cauliflower plants followed faba bean, compared with field pea and wheat, but no difference was found regarding the biomass production in broccoli. The higher percentage of plants set curds （either broccoli or cauliflower） was obtained in the variants followed faba bean and then field pea. The same was true regarding total curd yield and the average curd weight for both： broccoli and cauliflower.
基金supported by the National Natural Science Foundation of China (31570634)the Project of Xinjiang Agricultural Vocational College (XJNZYKJ201712)
文摘Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.
