Cladistic biogeographic analysis suggests an early Caribbean diversification in Mexico

The Great American Biotic Interchange has been the predominant paradigm for explaining biotic diversification in the Nearctic/Neotropical overlap or Mexican Transition Zone, which is commonly explained by the collision of the North and South American continental plates, which began in the Oligocene and fused both landmasses. In the most far-reaching cladistic biogeographical analysis of the area to date, evidence has been found supporting the existence of a remnant Caribbean region extending from eastern Mexico to southeastern USA, a hypothesis that challenges current views of the Great American Biotic Interchange and the Mexican Transition Zone. We show herein that an older terrane, which has drifted to the present day positions of Yucatan and Cuba, may be biogeographically linked to an early ‘Gondwanan’ biota of the Paleocene (ca. 60 Ma). The evidence indicates an east–west biotic divide in Mexico, existing before the collision and formation of Central America. The south–north division of the country, previously recognized by several authors as associated with the Great American Biotic Interchange and the Mexican Transition Zone, is of a younger age. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

明太祖的荒政立法

救荒是明代经济发展、社会稳定的重要措施。为了保证荒政的顺利而有效地进行,明太祖从灾害防治到灾害赈济,从赈灾官员的选用到对吏治腐败的整治,都制定了较为详细的法律条文。从这些法律条文中可以概括出明太祖的荒政立法包含以下两个方面：一、防灾与减灾中的立法;二、救灾中的立法。朱元璋通过荒政立法,一方面惩治了救灾中的腐败,提高了救灾的效率;另一方面也使灾民在自然灾害面前得到国家的救济,使社会生产力的破坏得以减轻,为明王朝的经济恢复和发展奠定了基础。     

联合基于野外的代谢组学和化学分析手段筛选优先关注新兴污染物：在五大湖流域的案例研究

由于毒性评估项目很难与日渐增长的需要测试的污染物保持同步,所以较难将关注点集中在影响水生生态系统的最为生物相关的污染物上。由于评估潜在毒性污染物所造成的生物影响已被证明是有效的,内生性代谢物的研究（代谢组学）对于剔除那些较低可能造成生物影响的污染物或许有一定帮助,从而找出生物重要性最高的污染物。本研究在北美五大湖流域的18个地点针对置于笼中的黑头软口鲦（Pimephales promelas）进行实验。我们测定了水体温度和水样中的污染物浓度（目标污染物132种,检出86种）,并使用1H-NMR谱测量了肝极性提取物中的内生性代谢物。利用偏最小二乘法回归来比对内生性代谢物的相对丰度与污染物浓度和环境温度。结果表明内生性极性代谢物的指标与最多49种污染物存在共同变化。因此我们认为至多52%的检出污染物与内生性代谢物变化的共同变化不显著,表明这些污染物很可能不会在这些地点造成可以检测到的影响。这是通过缩短对于实验地点有着潜在影响的污染物列表从而扫描出检出污染物生物相关性的第一步。类似的信息有助于风险评估者区分不同污染物的重要性并将重点毒性测试放在最为生物相关的污染物上。
精选自Nicol Janecko, Lucie Pokludova, Jana Blahova, Zdenka Svobodova, Ivan Literak. Linking field-based metabolomics and chemical analyses to prioritize contaminants of emerging concern in the Great Lakes basin. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2493–2502, October 2016. DOI: 10.1002/etc.3409
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3409/full
     

Changes in Avian and Plant Communities of Aspen Woodlands over 12 Years after Livestock Removal in the Northwestern Great Basin

Abstract: Riparian and quaking aspen (Populus tremuloides) woodlands are centers of avian abundance and diversity in the western United States, but they have been affected adversely by land use practices, particularly livestock grazing. In 1990, cattle were removed from a 112,500‐ha national wildlife refuge in southeastern Oregon. Thereafter, we monitored changes in vegetation and bird abundance in years 1–3 (phase 1) and 10–12 (phase 2) in 17 riparian and 9 snow‐pocket aspen plots. On each 1.5‐ha plot, we sampled vegetation in 6 transects. Three times during each breeding season, observers recorded all birds 50 m to each side of the plot's 150‐m centerline for 25 minutes. We analyzed data with multivariate analysis of variance and paired t tests with p values adjusted for multiple comparisons. In both periods, riparian and snow‐pocket aspen produced extensive regeneration of new shoots ( stems/ha and 7079 stems/ha, respectively). By phase 2, a 64% increase in medium‐diameter trees in riparian stands indicated successful recruitment into the overstory, but this pattern was not seen in snow‐pocket stands, where the density of trees was over 2 times greater. By phase 2 in riparian and snow‐pocket stands, native forb cover had increased by 68% and 57%, respectively, mesic shrub cover had increased by 29% and 58%, and sagebrush cover had decreased by 24% and 31%. Total avian abundance increased by 33% and 39% in riparian and snow‐pocket aspen, respectively, ground or understory nesters increased by 133% and 67% and overstory nesters increased by 34% and 33%. Similarly, ground or understory foragers increased by 25% and 32%, aerial foragers by 55% and 57%, and overstory foragers by 66% and 43%. We interpreted the substantial regeneration of aspen shoots, increased densities of riparian forbs and shrubs, and increased avian abundances as a multitrophic‐level response to the total removal of livestock and as substantial movement toward recovery of biological integrity.     

How sensitive are elasticities of long-run stochastic growth to how environmental variability is modelled?

A variable environment leaves a signature in a population's dynamics. Deriving statistical and mathematical models of how environmental variability affects population projections has - in the wake of reports of substantial climatic fluctuations - received much recent attention. If the model changes, then so too does the population projection. This is because a different model of environmental variability changes estimates of long-run stochastic growth, which is a function of demographic rates and their temporal sequence. Decomposing elasticities of long-run stochastic growth into constituent parts can assess the relative influence of different components. Here, we investigate the consequences of changing the environmental state definition, and therefore altering the shape of demographic rate distributions and their temporal sequence, by using age-structured matrix models to project vertebrate populations into the future under a range of environmental scenarios. The identity of the most influential demographic rate was consistent among all approaches that perturbed only the mean, but was not when only the variance was perturbed. Furthermore, the influence of each demographic rate fluctuated among projections by up to factors of six and two for changes to the variance and mean, respectively. These changes in influence depend in part upon how environmental variability - in particular, the color of environmental noise - is incorporated. In the light of predictions of increasing climatic variability in the future, these results suggest caution when drawing quantitative conclusions from stochastic population projections.     

LAKE SUPERIOR REGULATION EFFECTS

ABSTRACT: The outflows of Lake Superior through the St. Marys River have been modified from natural conditions, initially by the construction of engineering works, such as bridges, and later by the construction of control works and the regulation of the lake. For all practical purposes, the period from 1860 to 1887 represents the natural river conditions. During the period 1888-1900 the regimen was modified by the construction of the International Railroad Bridge and the Chandler-Dunbar Power Canal. In 1901 construction began on the compensating works. Following the completion of the compensating works in August 1921, the Lake Superior outflows were regulated in accordance with the Orders of Approval, 26 and 27 May 1914. A hydrologic response model was developed to simulate the natural Lake Superior regime. The model was run for the 1860–1975 period to simulate natural Lake Superior levels and outflows. The simulated levels were compared with the recorded levels to determine the effect of regulation. It was found that regulation has resulted in a rise in Lake Superior water levels. The simulated natural outflows for the period from 1937 to 1975 were run through the Great Lakes hydrologic response model to analyze the regulation effects on Lakes Michigan-Huron, St. Clair, and Erie. The results show no long-term bias due to regulation.     

长江大保护5年来流域土地利用和生态系统服务变化

2016年我国开始实施长江大保护战略,防护林建设、港口码头整治、岸线复绿等一系列生态保护修复措施得以落实。以2010年、2015年、2020年3期遥感解译的土地利用数据为基础,对比分析前5年（2010—2015年）和后5年（2015—2020年）长江流域土地利用和生态系统服务变化,以及河湖滨岸缓冲带土地利用和港口码头分布变化,以考察长江大保护的成效。结果表明：1）2015—2020年,长江经济带6大城市群、重要保护区域及主要河湖缓冲区的土地利用转化主要表现为耕地和林草地转为建设用地。与前5年相比,长江流域生态系统综合动态度、生态用地变化指数和开发干扰指数都在下降,土地利用变幅与动态度都趋于平缓。2）2015—2020年,主要河湖缓冲区（0~5 km）的林草地、耕地和未利用地面积减少,湿地和建设用地面积增加。与前5年相比,河湖滨岸带港口码头总数量和总面积都由明显增加转为有所减少。3）2015—2020年,长江流域生长季植被覆盖度呈上升趋势。与前5年相比,高等级植被覆盖度面积持续增加,较低、中等和较高等级面积都持续减少。4）2015—2020年,生态用地面积与质量基本稳定。与前5年相比,生态系统服务综合当量由略有升高到保持稳定,变化趋于平缓。     

西部大开发面临的环境挑战及其对策

西部大开发面临的环境挑战主要是生态脆弱性的加重和环境污染西迁速度的加快。面对挑战,需要采取的对策及措施主要有:认真开 展对生态环境的科学研究;加强与拓展环境影响评价工作;切实加强环境管理能力建设;努力加大生态保护与建设的力度;坚决遏制环境污染 的西迁;制定与实施“西部蓝天计划”;大力加强水资源的保护与有效利用等。      

EVALUATION OF GREAT LAKES NET BASIN SUPPLY FORECASTS1

ABSTRACT: Evaluation of the Great Lakes Environmental Research Laboratory's (GLERL's) physically-based monthly net basin supply forecast method reveals component errors and the effects of model improvements for use on the Laurentian Great Lakes. While designed for probabilistic outlooks, it is assessed for giving deterministic outlooks along with other net basin supply forecast methods of the U.S. Army Corps of Engineers and Environment Canada, and with a stochastic approach commissioned by the Corps. The methods are compared to a simple clima-tological forecast and to actual time series of net basin supplies. Aetual net basin supplies are currently determined by estimating all components directly, instead of as water-balance residuals. This is judged more accurate and appropriate for both forecasting and simulation. GLERL's physically-based method forecasts component supplies while the other methods are based on residual supplies. These other methods should be rederived to be based on component supplies. For each of these other methods, differences between their outlooks and residual supplies are used as error estimates for the rederived methods and component supplies. The evaluations are made over a recent period of record high levels followed by a record drought. Net basin supply outlooks are better than climatology, and GLERL's physically-based method performs best with regard to either component or residual net basin supplies. Until advances are made in long-range climate outlooks, deterministic supply outlooks cannot be improved significantly.     

Zinc and lead sequestration in an impacted wetland system

The fate and bioavailability of pollutant metals is important to the long-term health of freshwater wetland systems, particularly in areas with elevated background levels of trace metals. Precipitation of some authigenic mineral phases in wetland sediments can potentially limit metal bioavailability through sequestration in low-solubility compounds, such as metal sulfides. Zinc and Pb concentrations were analyzed in water, plant and sediment samples taken from a metal-contaminated wetland in Chicago, IL, USA in order to assess metal fate and bioavailability, while X-ray absorption spectroscopy (XAS) studies were conducted to determine zinc speciation in the wetland sediments. The results showed sequestration of metal into the pond sediments, most likely in iron precipitate phases. In surface sediments, re-release of Zn and Pb into pore waters was correlated with microbial iron reduction, while the presence of sulfide in anoxic pore waters corresponded to decreased dissolved concentrations of both elements. Analysis of extended X-ray absorption fine structure (EXAFS) data confirmed that sulfide compounds dominated zinc speciation throughout the sediment. Uptake of trace metals in Phragmites plants was limited primarily to plant roots, while concentrations of both Pb and Zn in aquatic vegetation were significantly elevated, representing a potential bioaccumulation hazard.