新烟碱类杀虫剂污染特征及其毒性效应

综述了新烟碱类杀虫剂在土壤、水体和大气中的赋存现状及其对无脊椎动物、脊椎动物和人类的毒性效应.新烟碱类杀虫剂普遍存在于多介质环境中,特别在农业种植区具有较高的残留浓度.新烟碱类杀虫剂对非靶标动物的影响主要表现在氧化应激、抑制活动能力、损伤DNA和生育功能;亦会对人类的生育、生殖、神经以及脏器功能带来风险.因此,今后亟需系统研究新烟碱类杀虫剂在多环境介质中的赋存及污染状况,深入探讨新烟碱类杀虫剂对非靶标生物的健康危害,以便全面了解此类杀虫剂对生态环境及非靶标生物造成的潜在风险.     

绿狐尾藻对铜绿微囊藻和羊角月牙藻的抑藻效应

分别将不同起始浓度(10~5、10~6、10~7、10~8和10~9ind.·L~(-1))的铜绿微囊藻和羊角月牙藻分组与绿狐尾藻进行共培养,连续10 d,每天测定各组铜绿微囊藻或羊角月牙藻的光密度值,用以确定绿狐尾藻对两种藻类不同浓度的生长抑制情况.结果表明,2. 5 g·(200 m L)~(-1)的绿狐尾藻对起始浓度为10~7ind.·L~(-1)和10~8ind.·L~(-1)的铜绿微囊藻具有明显的抑制作用;而对实验所设的所有起始浓度的羊角月牙藻生长均没有显著的抑制作用.并且,采用溶剂浸提与气相色谱-质谱联用(GC-MS)测定的方法,分析了绿狐尾藻粉末浸提液和绿狐尾藻生长液中可能存在的化感物质,通过分析,确定棕榈酸是绿狐尾藻分泌的化感物质之一,并且发现了3种可能是绿狐尾藻分泌的新型化感物质:3-乙基-3-甲基庚烷、磷酸三乙酯和酞酸二丁酯.     

Evaluating unintended consequences of intentional species introductions and eradications for improved conservation management

Increasingly intensive strategies to maintain biodiversity and ecosystem function are being deployed in response to global anthropogenic threats, including intentionally introducing and eradicating species via assisted migration, rewilding, biological control, invasive species eradications, and gene drives. These actions are highly contentious because of their potential for unintended consequences. We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. To evaluate conservation outcomes, we developed a community assessment framework for systematically mapping the range of possible interaction types for 111 case studies. Applying this tool, we quantified the number of interaction types considered in each study and documented the nature and strength of intended and unintended outcomes. Intended outcomes were reported in 51% of cases, a combination of intended outcomes and unintended outcomes in 26%, and strictly unintended outcomes in 10%. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs. unintended effects), some unintended effects were fairly innocuous relative to the conservation objective, whereas others resulted in serious unintended consequences in recipient communities. Studies that assessed a greater number of community interactions with the target species reported unintended outcomes more often, suggesting that unintended consequences may be underreported due to insufficient vetting. Most reported unintended outcomes arose from direct effects (68%) or simple density-mediated or indirect effects (25%) linked to the target species. Only a few documented cases arose from more complex interaction pathways (7%). Therefore, most unintended outcomes involved simple interactions that could be predicted and mitigated through more formal vetting. Our community assessment framework provides a tool for screening future conservation actions by mapping the recipient community interaction web to identify and mitigate unintended outcomes from intentional species introductions and eradications for conservation.     

Impact of bias in predicted height on tree volume estimation: A case-study of intrinsic nonlinearity

Bias originating from intrinsic nonlinearity in nonlinear models is caused by excess curvature in the solution locus of parameter estimates derived from least squares procedures. Bias due to intrinsic nonlinearity varies according to sample size as well as model specification. This paper analyses consequences of fractionising data into smaller sub-samples. Based on measurements of stem diameter and total tree height from the first Danish national forest inventory, it is demonstrated how data splitting at random may cause the intrinsic nonlinear curvature to exceed the critical F-value. Application of a Taylor-series expansion shows that, for all practical purposes, the bias in predictions of individual tree volume (based on stem diameter and tree height) is negligible. To minimize residual variance, intrinsic curvature and, in turn, prediction bias, it is recommended that data be stratified according to site conditions, stand characteristics or other relevant criteria. Finally, the preferred model should exhibit close-to-linear behaviour.     

Simulating dynamic and mixed-severity fire regimes: A process-based fire extension for LANDIS-II

Fire regimes result from reciprocal interactions between vegetation and fire that may be further affected by other disturbances, including climate, landform, and terrain. In this paper, we describe fire and fuel extensions for the forest landscape simulation model, LANDIS-II, that allow dynamic interactions among fire, vegetation, climate, and landscape structure, and incorporate realistic fire characteristics (shapes, distributions, and effects) that can vary within and between fire events. We demonstrate the capabilities of the new extensions using two case study examples with very different ecosystem characteristics: a boreal forest system from central Labrador, Canada, and a mixed conifer system from the Sierra Nevada Mountains (California, USA). In Labrador, comparison between the more complex dynamic fire extension and a classic fire simulator based on a simple fire size distribution showed little difference in terms of mean fire rotation and potential severity, but cumulative burn patterns created by the dynamic fire extension were more heterogeneous due to feedback between fuel types and fire behavior. Simulations in the Sierra Nevada indicated that burn patterns were responsive to topographic features, fuel types, and an extreme weather scenario, although the magnitude of responses depended on elevation. In both study areas, simulated fire size and resulting fire rotation intervals were moderately sensitive to parameters controlling the curvilinear response between fire spread and weather, as well as to the assumptions underlying the correlation between weather conditions and fire duration. Potential fire severity was more variable within the Sierra Nevada landscape and also was more sensitive to the correlation between weather conditions and fire duration. The fire modeling approach described here should be applicable to questions related to climate change and disturbance interactions, particularly within locations characterized by steep topography, where temporally or spatially dynamic vegetation significantly influences spread rates, where fire severity is variable, and where multiple disturbance types of varying severities are common.     

Maternal investment in eggs is affected by male feet colour and breeding conditions in the blue-footed booby, <Emphasis Type="Italic">Sula nebouxii</Emphasis>

Females are expected to vary investment in offspring according to variables that may influence the offspring fitness in a way that optimises her inclusive fitness for a particular context. Thus, when sexual ornaments signal the quality of the male, females might invest in reproduction as a function of the attractiveness of their mate. We tested whether breeding conditions and male feet colour influence reproductive decisions of blue-footed booby females. In the blue-footed booby, male feet colour is a dynamic condition-dependent sexually selected trait that is related to paternal effort. During two consecutive years, an El Niño year (poor breeding conditions) and a year with good breeding conditions, we experimentally reduced male attractiveness by modifying their feet colour after the first egg was laid and recorded female investment in the second egg. We found that, relative to the first egg in the clutch, females laid heavier second eggs during the poor year than during the good year. Females paired with males with duller feet colour reduced second-egg mass and volume and delayed the laying of the second egg, independently of the year. Absolute yolk androstenedione (A4) concentration (but not testosterone, T) in second eggs was higher during a poor year than during a good year. Only during a year with poor breeding conditions, females paired with experimental males decreased the relative A4 concentration (but not T) in the second egg compared to control females. Thus, blue-footed booby females probably favour brood reduction by decreasing egg quality and increasing size asymmetry between chicks when the breeding and the mate conditions are poor.     

“耕地总量动态平衡”政策驱动下中国的耕地变化及其生态环境效应

土地政策是影响土地利用及生态环境变化的一个重要的驱动因素。论文分析了“耕地总量动态平衡”政策对中国的耕地变化及其生态环境效应的影响,结果表明,“耕地总量动态平衡”政策对中国耕地的数量变化产生了积极作用,主要表现为:非农建设占用耕地的势头总体上得到遏制,全国及各省(市、区)基本实现耕地占补平衡,促进了农地整理工作的开展。但是,该政策对中国耕地的质量变化的影响却相反,在全国实现耕地占补平衡的情况下,耕地的总体生产能力呈下降趋势,同时,对生态环境产生了一定的负面效应。在此基础上,论文提出了重新审视“耕地总量动态平衡”政策的可行性,以“保护和提高耕地综合生产能力”替代“耕地总量动态平衡”以及根据土地资源区域差异采取不同的具体措施等对该政策加以调整的思路。     

沂蒙山区典型小流域特殊降雨的磷素输出特征

为揭示沂蒙山区不同降雨条件下的磷素流失规律,对当地孟良崮小流域2010年13场自然降雨径流量及磷素浓度的动态过程进行实地监测,研究了年内产生有效径流的首场和最大强度2场特殊降雨的径流、磷素输出负荷、初期冲刷效应及径流量同磷素负荷之间的关系.结果表明,首场降雨径流中溶解态有机磷(DOP)、溶解态无机磷(DIP)、溶解态全磷(DP)、颗粒态全磷(PP)和总磷(TP)浓度明显高于最大强度降雨,而其输出负荷分别为最大强度降雨的168%、54%、71%、48%和54%;2场降雨对小流域磷素年输出负荷有重要影响,DOP、DIP、DP、PP和TP的输出总量分别占整个雨季输出的48%、81%、70%、87%和81%,其中DIP占DP流失的77%,PP占TP流失的71%;2场降雨均存在污染物的初期冲刷效应,最大强度降雨的初期冲刷效应较首场降雨强烈;2场降雨的各磷素累积输出负荷同累积径流量之间均呈线性关系,且拟合度较好,但首场降雨各形态磷素直线方程的斜率均大于最大强度降雨.根据气象预报尽量减少在特殊降雨期间翻耕、施肥等农事活动,以及有针对性地建立沟渠、池塘等截污措施减少初期冲刷效应,是降低农业非点源污染的有效途径.     

农业资源开发中的耦合效应

论文研究了农业系统的耦合效应,以达到提高农业资源利用率的目的。基于对农业资源特性的分析,肯定了农业资源开发进行系统耦合的必要性。重点论述了农业系统的涵义,并将其分为6个生产层,表述了每个生产层的特点,这为农业系统耦合提供某些理论基础。设计了农业系统耦合的结构要素,通过各结构要素在时序性、空间格局和生态过程上的相互联系和相互作用,将其结构要素耦合成为一个优势互补的农业系统。这个设计在马坪镇实施,取得显著的耦合效应。由此,讨论了在农业资源开发中如何发挥耦合效应的问题。     

Se(Ⅳ)和Se(Ⅵ)对小白菜生长及生理效应的影响

用盆栽试验研究了不同含量Se(Ⅳ)和Se(Ⅵ)对小白菜生长和生理效应的影响.结果表明,不同含量Se(Ⅳ)和Se(Ⅵ)对小白菜体生长和生理代谢的影响不尽相同.低含量硒（Se(Ⅳ)<10.0 mg·kg-1、Se(Ⅵ)<5.0 mg·kg-1）能够促进小白菜的生长,使其根变粗, 诱导脯氨酸的产生,阻止丙二醛（MDA）的合成,增强白菜的抗逆性,使其生物量明显提高;高含量硒会抑制小白菜的生长,导致植物体内脯氨酸合成下降,MDA含量增加,叶及根系生长受到抑制,地上和地下部干重显著急速下降（p<0.01）.小白菜根长、叶面积等生长指标均随Se(Ⅳ)和Se(Ⅵ)含量的增大而显著下降（p<0.01）;抑制小白菜根系生长的Se(Ⅳ)含量为60 mg·kg-1,明显高于Se(Ⅵ)含量（20.0 mg·kg-1）.相同硒含量下,Se(Ⅳ)处理的小白菜地上部干重为Se(Ⅵ)的1.1~3.0倍,说明本试验条件下Se(Ⅵ)的生物有效性和毒性均大于Se(Ⅳ).Se(Ⅵ)处理小白菜地上部分的硒含量显著高于地下部分,而Se(Ⅳ)处理小白菜地下部分的硒含量显著高于地上部分,小白菜地上和地下部分对Se(Ⅵ)的吸收量均显著高于Se(Ⅳ).综合生长和生理因子分析表明,地上部分生物量是反映Se(Ⅳ)及Se(Ⅵ)处理土壤上小白菜生长状况的理想指标.