甜瓜种子萌发和幼苗生长对NaCl胁迫的响应

在盆栽条件下研究了NaCl胁迫对黄河蜜和白沙蜜甜瓜种子萌发和幼苗生长的影响。结果表明:NaCl胁迫对甜瓜种子吸水和累计发芽率影响较小,但明显延缓后期吸水和发芽进程。50 mmol·L-1以上NaCl浓度下,甜瓜种子相对发芽指数、相对活力指数和胚根生长量均下降。NaCl胁迫抑制甜瓜幼苗高度、株叶面积增长和干物质积累,抑制作用具有浓度和时间依赖性。NaCl胁迫对甜瓜幼苗形态生长的抑制作用强于对物质积累的抑制作用,对根系干物质积累的抑制作用高于对地上部干物质积累的抑制作用,对白沙蜜的抑制作用强于对黄河蜜的抑制作用。甜瓜种子和幼苗能适应的临界NaCl浓度在100~150 mmol·L-1之间,厚皮甜瓜可能更适合作为咸水灌溉和盐碱地生产的经济作物。     

我国高寒草甸植被生产力及其影响因子

生物量是重要的植物群落数量特征，直接反映生态系统生产者的物质生产量，是生态系统生产力的重要体现。高寒草甸广泛分布于青藏高原，是高寒生态系统的主要植被类型。回顾了高寒草甸生物量的研究成果。高寒草甸生物量呈典型的金字塔式垂直分布格局，地上生物量主要集中于0—10cm的冠层，地下生物量也集中分布于0—10cm的土层内。增温和多雨会降低生物量，叶面积和物种丰富度与地上生物量成正相关关系，氮素的增加有助于植被生物量的增长，而放牧率与生物量成显著负相关。     

辽东栎萌生个体的地上生物量及其构件分配与生长参数的关系

选择岷江上游海拔2100-2300m地段的辽东栎萌生株个体69株,测定了每株生长参数（年龄、高度、基径、冠幅）、各器官生物量及地上总生物量,分析了各器官生物量及构件分配与生长参数的相互关系。结果表明,辽东栎萌生株构件分配的大小排序为：茎干〉枝〉皮〉叶：随径级增大。茎干、大枝生物量所占总生物量比例上升,其他器官所占比例减小。辽东栎年龄与高度呈S曲线关系,其他均表现出很好的幂指数函数关系;各构件器官生物量与生长参数大多也呈幂指数函数W=aD^h（D为基径）关系。基径为估测辽东栎萌生株地上各器官生物量及总生物量的最佳因子。     

Wetland vegetation biomass estimation and mapping from Landsat ETM data:a case study of Poyang Lake

Poyang Lake is the largest freshwater lake in China. This paper conducted a digital and rapid investigation of the lake’s wetland vegetation biomass using Landsat ETM data acquired on April 16, 2000. First, utilizing the false color composite derived from the ETM data as one of the main references, the authors designed a reasonable sampling route for field measurement of the biomass, and carried it out on April 18-28, 2000. Then after both the sampling data and the ETM data were geometrically corrected to an equal-area projection of Albers, linear relationships among the sampling data and some transformed data derived from the ETM data and the ETM 4 were calculated. The results show that the sampling data is best relative to the band 4 data with a high correlation coefficient of 0.86, followed by the DVI and NDVI data with 0.83 and 0.80 respectively. Therefore, a linear regression model, which was based on the field data and band 4 data, was used to estimate the total biomass of entire Poyang Lake, and then the map of the biomass distribution was compiled.     

中国南京与美国德克萨斯稻田甲烷排放的比较

Field measurements of methane emission from rice paddies were made in Nanjing, China and in Texas, USA, respectively. Soil temperature at approximately 10 cm depth of the flooded soils was automatically recorded. Aboveground biomass of rice crop was measured approximately every 10 days in Nanjing and every other week in Texas. Seasonal variation of soil temperature in Nanjing was quite wide with a magnitude of 15.3℃ and that in Texas was narrow with a magnitude of 2.9℃. Analysis of methane emission fluxes against soil temperature and rice biomass production demonstrated that the seasonal course of methane emission in Nanjing was mostly attributed to soil temperature changes, while that in Texas was mainly related to rice biomass production. We concluded that under the permanent flooding condition, the seasonal trend of methane emission would be determined by the soil temperature where there was a wide variation of soil temperature, and the seasonal trend would be mainly determined by rice biomass production if there are no additional organic matter inputs and the variation of soil temperature over the rice growing season is small.     

Biomass burning in the tropical savannas of Ivory Coast: An overview of the field experiment Fire of Savannas (FOS/DECAFE 91)

FOS/DECAFE 91 (Fire of Savannas/Dynamique et Chimie Atmosphérique en Forêt Equatoriale) was the first multidisciplinary experiment organized in Africa to determine gas and aerosol emissions by prescribed savanna fires. The humid savanna of Lamto in Ivory Coast was chosen for its ecological characteristics representative of savannas with a high biomass density (900 g m^–2 dry matter). Moreover the vegetation and the climate of Lamto have been studied for more than twenty years. The emission ratios (X/CO₂) of the carbon compounds (CO₂, CO, NMHC, CH₄, PAH, organic acids and aerosols), nitrogen compounds (NO_x, N₂O, NH₃ and soluble aerosols) and sulfur compounds (SO₂, COS and aerosols) were experimentally determined by ground and aircraft measurements. To perform this experiment, 4 small plots (100×100 m) and 2 large areas (10×10 km) were prepared and burnt in January 1991 during the period of maximum occurrence of fires in this type of savanna. The detailed ecological study shows that the carbon content of the vegetation is constant within 1% (42 g C for 100 g of vegetal dry matter), the nitrogen content (0.29 g N for 100 g of dry matter) may vary by 10% and the sulfur content (0.05 g S/100 d.m.) by 20%. These variations of the biomass chemical content do not constitute an important factor in the variation of the gas and particle emission levels. With the emission ratios characteristic of humid savanna and flaming conditions (CO/CO₂ of 6.1% at the ground and 8% for airborne measurements), we propose a set of new emission factors, taking into account the burning efficiency which is about 80%: 74.4% of the carbon content of the savanna biomass is released to the atmosphere in the form of CO₂, 4.6% as CO, 0.2% as CH₄, 0.5% as NMHC and 0.7% as aerosols. 17.2% of the nitrogen content of the biomass is released as NO_x, 3.5% as N₂O, 0.6% as NH₃ and 0.5% as soluble aerosols.     

Interannual climate variation,land type and village livelihood effects on fires in Kalimantan,Indonesia

The increasing extent and frequency of fires globally requires nuanced understanding of the drivers of large-scale events for improved prevention and mitigation. Yet, the drivers of fires are often poorly understood by various stakeholders in spatially expansive and temporally dynamic landscapes. Further, perceptions about the main cause of fires vary amongst stakeholders, which amplify ongoing challenges from policies being implemented inconsistently across different governance levels. Here, we develop a spatially and temporally-explicit typology of fire prevalence across Kalimantan, Indonesia, a region with significant contribution to global greenhouse gas emissions. Based on livelihood information and data on climate, soil type and forest degradation status, we find that in intact forest the density of fires in villages that largely coincide with oil palm concessions was twice as high as in villages outside the concessions across all years. Fires occurring in degraded land on mineral soil across all years were also most prevalent in villages with industrial plantations (oil palm or timber). On the other hand, in degraded peatland, where fires are most intense during dry years induced by the El Niño episodes, occurrence rates were high regardless of village primary livelihoods. Based on these findings we recommend two key priorities for fire mitigation going forward for policy across different governance levels in Kalimantan: degraded peatland as the priority area and industrial plantations as the priority sector. Our study suggests a fire prevention and mitigation approach, which accounts for climate, land type and village livelihood, has the potential to deliver more effective means of management.     

Isoprene emissions from vegetation and hydrocarbon emissions from bushfires in tropical Australia

Information from a variety of sources, including an airborne field expedition in November 1985, is used to produce estimates of the annual emissions of some hydrocarbons from bushfires, and isoprene from trees, in tropical Australia. For the continent north of 23° S the annual bushfires (biomass burning) input was estimated, in units of Tg carbon, to be 2 TgC (uncertainty range 0.8–5 TgC), emitted predominantly during the May to October dryseason. Isoprene emissions during this period were estimated also to be 2 TgC (uncertainty range 0.5–8 TgC), but were estimated to be an order of magnitude higher during the November to April wet season, at a level of 23 TgC (uncertainty range 6–100 TgC).The large annual emission of isoprene over the tropical part of the Australian continent yields ppbv levels of isoprene measured at the surface in summertime. Isoprene reactivity with hydroxyl radical is such that at these concentrations isoprene must be a dominant factor in controlling the concentration of OH radical in the convective boundary layer. Simple arguments based on the convective velocity scale suggest that the shape of the isoprene vertical profile in November 1985 would be consistent with available data on the OH-isoprene reaction rate if OH concentration in the boundary layer averaged about 2.5×10⁶ cm^-3 over the middle part of the day.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden.     

2017—2021年长江天鹅洲故道鱼类群落结构变化、成因分析及对长江江豚迁地保护的启示

长江天鹅洲故道是长江江豚首个迁地保护区,其中充足而适口的饵料鱼类资源是长江江豚种群健康发展的保障。为此,根据2017年10月—2021年4月对长江天鹅洲故道进行的7次鱼类调查数据,结合禁捕前的历史数据,对其鱼类群落结构演变进行了分析,并针对长江江豚饵料鱼的供应状况对天鹅洲故道内鱼类资源管理提出了建议。调查期间,共采集到鱼类57种,其中,蒙古鲌(Culter mongolicus)、鲢(Hypophthalmichthys molitrix)和鳙(Aristichthys nobilis)等大中型鱼类生物量明显增加,而?(Hemiculter leucisculus)和似鳊(Pseudobrama simoni)等小型鱼类生物量呈现下降趋势。鱼类群落优势种逐渐由太湖新银鱼(Neosalanx taihuensis)、短颌鲚(Coilia brachygnathus)和?等小型鱼类转变为鳙、蒙古鲌和拟尖头鲌(Culter oxycephaloides)等大中型鱼类,尤其是新近出现的拟尖头鲌种群发展迅速。同时,短颌鲚和?等小型鱼类的体重在减小,而鲢、鳙等大中型鱼类规格在持续提高。长江江豚以小...     

Wheat straw burning and its associated impacts on Beijing air quality

Based on MODIS images, large-scale flow field charts and environmental monitoring data, we thor- oughly analyzed the spatial distribution of wheat straw burning in North China, with focus on its envi- ronmental impacts on the air quality of Beijing and pollution transport paths. And we anatomized changes of air quality in Beijing under the impacts of pollution generated by wheat straw burning around. The results indicate that: (1) The North China Plain, a winter-wheat growing area, is the main source of pollutants induced by wheat straw burning in Beijing. The direction of south-west is the dominant heavy pollution transport path. (2) Impacts of wheat straw burning on air quality are mainly manifested by significantly increasing CO concentration. (3) Precursors of O3 generated by wheat straw burning, combining with favorable meteorological conditions, can induce increasing O3 concentration greatly. NO concentration will be greatly increased due to decreasing O3 concentration at night. (4) Atmospheric particles, especially the fine ones, from wheat straw burning exert considerable influ- ence on Beijing air quality. (5) Different contributions of wheat straw burning to pollutants are identified. Ratios of PM10/SO2, CO/SO2, etc., can be applied to indicate pollution extent of wheat straw burning. High ratios of PM10/SO2 and CO/SO2 show that the air quality was heavily impacted by wheat straw burning and these ratios can be employed as indicators of contribution of wheat straw burning to the degradation of Beijing air quality. (6) Randomness of wheat straw burning activities renders random outbreak of air pollution of this type. Regional and extensive wheat straw burning activities can cause serious air pollution event.