华中地区水旱轮作模式下水稻季施氮肥对油菜季施氮肥土壤N2O排放的影响

设置了水稻季与油菜季均不施用氮肥(N0-0);水稻季施用氮肥150 kg·hm-2(以N计,下同),油菜季不施用氮肥(N150-0);水稻季与油菜季均施用氮肥150 kg·hm-2(N150-150);水稻季不施用氮肥,油菜季施用氮肥150 kg·hm-2(N0-150)4种施肥处理,采用静态箱/气相色谱法对旱作油菜季N_2O的排放进行了原位观测(2016年9月—2017年4月),研究了华中地区水旱轮作模式下水稻季施肥对油菜季土壤N_2O排放的影响.结果表明,油菜季N_2O排放主要集中在施基肥后1周内.N0-0、N150-0、N150-150和N0-150处理N_2O排放通量变化范围分别为-10.81~181.26、-20.48~95.61、-8.87~638.56和-21.76~827.86μg·m-2·h-1,平均排放通量分别为4.58、3.89、21.06和27.24μg·m-2·h-1,N_2O累积排放量分别为0.20、0.17、0.92和1.19 kg·hm-2,施氮肥处理(N150-150和N0-150)N_2O排放量显著高于不施氮肥处理(N0-0、N150-0)(p0.05).N150-150和N0-150处理N_2O排放通量与土壤孔隙充水率(WFPS)具有显著正相关关系(p0.05);N150-150和N0-150处理N_2O排放通量与土壤可溶性有机氮(DON)和无机氮(NO-3-N和NH+4-N)具有显著正相关关系(p0.01).以上结果表明,油菜季N_2O排放与稻季施用氮肥无关,施氮肥对土壤活性氮含量的影响是导致N_2O排放差异的主要原因,而土壤孔隙充水率也是影响油菜季N_2O排放的重要环境因子.     

2013年长江丰水期河水化学特征及控制因素

为掌握长江河水化学组成特征及其控制因素,笔者运用Gibbs图、多种离子比例系数法和主成分分析法综合分析了长江流域丰水期河水化学及氢氧同位素特征。结果表明,长江丰水期河水主要来源为大气降水,河水化学类型主要为HCO₃·SO₄-Ca型,化学成分主要受流域内广泛分布的碳酸盐岩等岩石风化作用控制;河水pH值、HCO₃^-浓度沿长江径流方向降低,SO₄^2-、Ca²⁺浓度沿长江径流方向升高。2013年丰水期,长江河水化学组成特征变化的主要影响因子,是易溶盐岩溶解和人类活动(贡献率40%),其次为川贵及长江三角洲地区的酸雨沉降以及人为酸性废水排放促进了流域内石灰岩和富含碳酸盐的三叠系砂页岩溶解(贡献率20%),最后为硅酸盐矿物及其风化产物的溶解(贡献率19%)。为了解长江河水水质状况及其演变趋势,合理评价长江流域水资源提供很好的科学依据。     

水平潜流人工湿地脱氮功效中植物的作用

为了研究芦苇(Phragmites australis)在收割期前/后、湿地床体内部各个区域内、一年四季中在水平潜流人工湿地脱氮效用所起的作用,实验设置了有/无植物2组平行反应器。结果表明,芦苇在收割前/后对于水平潜流人工湿地脱氮效果均有促进作用,植物地上部分氮吸收量占湿地脱氮量的10.2%。在芦苇收割前/后(5月~9月、10月~次年5月),芦苇湿地日均脱氮量分别是无植物湿地的1.55倍与1.11倍。高、矮芦苇不同组织中总氮浓度分布趋势一致,2种芦苇各组织含量分别为:穗(28.69 g/kg)>叶(13.69 g/kg)>茎(5.31 g/kg)、穗(28.06 g/kg)>叶(14.61 g/kg)>茎(8.46 g/kg)。在湿地的各个沿程区域,总氮、氨氮累加去除率变化趋势一致,并且从反应器前部到尾部呈上升趋势,从上部到下部呈下降趋势。有芦苇湿地的脱氮效用优于无植物湿地,且底部氮积累含量也较少。一年四季中有芦苇湿地在各个季节脱氮量是无植物湿地的1.06~1.47倍。     

浙江来水与黄浦江上游支流总磷和氨氮变化规律分析

利用浙江来水汇入黄浦江上游支流的3个断面2000—2009年10年的总磷和氨氮监测资料,分别对同一断面在丰水期、平水湖、枯水期的浓度以及同一水期不同断面的浓度,利用SPSS统计分析软件,对总磷、氨氮的浓度变化规律进行分析,在此基础上采用Spearman秩相关分析方法进行相应的趋势分析,揭示出总磷、氨氮在不同水期、不同断面的变化规律以及浓度变化趋势。     

The effects of climate change on plant phenology

The available data on climate change over the past century indicate that the Earth is warming. Important biological events, including changes in plant phenology, have been reported in many parts of the world. We have explored some of these phenological changes in more than 650 temperate species, which have indicated the average advancement of 1.9 days per decade in spring events and average delay of 1.4 days per decade in autumnal events. Thus the average length of the growing season has extended by 3.3 days per decade.     

Correlates of bushmeat in markets and depletion of wildlife

We used data on number of carcasses of wildlife species sold in 79 bushmeat markets in a region of Nigeria and Cameroon to assess whether species composition of a market could be explained by anthropogenic pressures and environmental variables around each market. More than 45 mammal species from 9 orders were traded across all markets; mostly ungulates and rodents. For each market, we determined median body mass, species diversity (game diversity), and taxa that were principal contributors to the total number of carcasses for sale (game dominance). Human population density in surrounding areas was significantly and negatively related to the percentage ungulates and primates sold in markets and significantly and positively related to the proportion of rodents. The proportion of carnivores sold was higher in markets with high human population densities. Proportion of small‐bodied mammals (<1 kg) sold in markets increased as human population density increased, but proportion of large‐bodied mammals (>10 kg) decreased as human population density increased. We calculated an index of game depletion (GDI) for each market from the sum of the total number of carcasses traded per annum and species, weighted by the intrinsic rate of natural increase (r_max) of each species, divided by individuals traded in a market. The GDI of a market increased as the proportion of fast‐reproducing species (highest r_max) increased and as the representation of species with lowest r_max (slow‐reproducing) decreased. The best explanatory factor for a market's GDI was anthropogenic pressure—road density, human settlements with >3000 inhabitants, and nonforest vegetation. High and low GDI were significantly differentiated by human density and human settlements with >3000 inhabitants. Our results provided empirical evidence that human activity is correlated with more depleted bushmeat faunas and can be used as a proxy to determine areas in need of conservation action.     

Arctic marine mammal population status,sea ice habitat loss,and conservation recommendations for the 21st century

Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979–2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5–10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation.     

三峡工程对武湖地区生态环境影响及其对策

以实地考察和水文资料分析结果为依据，阐述了三峡工程对武湖地区防洪，春旱时灌溉和航运带来的有利影响，及枯季１～５月排水所产生的不利影响。建议加强湖区水利建设，提高电排能力；将地面高程１８Ｍ以下耕地退田还湖，以提高湖泊调蓄功能。     

Timber harvest calculations on a National Forest: A case study

Harvest calculations determine sawtimber flows from public lands and are closely scruntinized by a wide spectrum of forest users. This study examines the reliability of harvest calculations on a single national forest in New Mexico Forest Service determinations of an array of variables were reviewed and evaluated. The study revealed a lack of precision in Forest Service adherence to self-imposed procedural standards governing the calculation process. Timber sales have taken place on lands where such standards prohibit harvesting and these lands have been included in annual harvest calculations. Assumptions required by a mathematical model used by the Forest Service in calculating the harvest were not followed in the subsequent implementation of the harvest level. These factors suggest that the Forest Service could have significantly over-stated annual harvest rate for the first decade. Opportunities exist to improve the calculation, and benefits realized may greatly exceed additional costs of implementation