广州地区稻田甲烷排放连续自动监测

本文介绍了采用甲烷自动采集及分析测量系统在广州地区进行稻田甲烷排放通量监测的试验设计。     

施肥对稻田甲烷排放的影响

采用自动连续测量系统，对不同施肥情况下稻田甲烷排放通量进行了监测。结果表明：施肥是影响稻田甲烷排放的重要因素。增施有机肥会导致甲烷排放量增加．应用化肥可降低甲烷排放，有机肥加倍处理，３２ｄ甲烷总排放量１６．４０ｇＣＨ＿４／ｍ￣２，是化肥加倍处理的１．５６倍；常规施肥处理介于两者之间。略高于常规加倍处理。肥料种类对甲烷排放量也有影响。全施有机肥高于有机肥加化肥（１：１）组，施沼渣肥组次之，全化肥组排放量最低，不到全有机肥处理排放量的１／５．有机肥又以施人畜粪的甲烷排放率最高，绿肥次之，沼渣肥和稻草的甲烷排放率最低。有机肥的多级利用是减少稻田甲烷排放的一条重要途径。     

稻田甲烷排放量估算和减缓技术选择

根据中国不同生态类型地区的稻田甲烷排放通量，估算了中国稻田甲烷排放总量。结果表明，１９９０年中国稻田甲烷排放总量为１１．３３５Ｔｇ。提出了一些减缓稻田甲烷排放措施，包括：（１）使用稻田甲烷抑制剂；（２）肥料管理；（３）水分管理；（４）筛选低排放率、高产的水稻品种。     

稻田施用沼渣对甲烷排放通量的影响

通过网室小区试验，观测得出：（１）４种沼渣处理和单施化肥处理的一季稻田平均甲烷排放通量为０．５６９～２．１８８ｍｇ０￣２·ｈ，两者无显著差异；农家肥处理稻田的平均甲烷排放通量为４４．１８ｍｇ／ｍ￣２·ｈ显著高于前两种处理，表明施用沼渣和化肥比施用农家肥能显著减少稻田甲烷排放量；（２）各处理稻田甲烷排放通量峰值期部出现在水稻蘖期至拔节初期，表明这一时期是控制稻田甲烷排放总量的关键时间；（３）各处理甲烷排放通量分别与淹水前各处理土壤及供试有机肥的易矿化碳含量、ＣＨ＿４－Ｃ含量呈显著正相关关系，这表明土壤易矿化碳含量是形成稻田甲烷的重要条件；（４）各处理之间水稻产量没有明显差异。     

控制稻田甲烷排放的农业技术选择

本文探讨了通过农业技术措施，控制稻田甲烷排放以及减少甲烷排放的潜力。试验结果表明：（１）用沼渣代替农家肥堆肥作基肥时，４种沼渣基肥处理中，有３种处理稻田甲烷排放通量比施农家肥的处理减少２４～６２％，比单纯施化肥处理减少１１～５６％；１种沼渣（马粪）由于腐熟度不够，其处理甲烷减排效果不明显；（２）改换氮肥的施用种类。以硝铵、硫铵代替尿素作追肥，甲烷排放通量分别减少２６％和４６％；（３）稻田的科学灌溉技术，从水用分蘖到抽穗期间，间歇落干，可以明显减少甲烷排放，而对产量无影响；（４）水稻半旱式栽培技术，也可明显抑制稻田甲烷排放。     

顶空气相色谱法测定稻田土壤甲烷产生率

介绍测定稻田土壤甲烷产生率的顶空气相色谱法。该法采用特制的不锈钢采样器，采取不同深度的土壤样品于已充满氮气的玻璃瓶中，通过抽空、充氮处理，使其处于厌氧状态，然后在不同时间间隔取上部气体样品分析甲烷浓度，再根据温度、体积、压力及干样重等参数计算甲烷产生率。本法标准偏差为１５．８７μＶ．ｓ（峰面积），变异系数为０．１８％（ｎ＝５）。     

我国南方红壤丘岗区稻田甲烷产生规律

温度对稻田甲烷产生有显著影响，温度每升高１０℃，甲烷产生率约增长３倍。水稻在插秧后和收割前出现甲烷产生高峰，在生长中期产生率较低。稻田土壤中甲烷产生率的垂直分布与有机酸含量的垂直分布一致。水稻植株对甲烷产生率有巨大影响，即种植水稻比不种水稻甲烷产生率显著增加。稻田土壤排到大气中的甲烷不到其产生量的２０％。     

我国南方红壤丘岚区稻田甲烷产生规律

温度对稻田甲烷产生有显著影响，温度每升高１０℃，甲烷产生率的增长３倍。水稻在插秧后和收割前出现甲烷产生高峰，在生长中期产生率较低。稻田土壤中甲烷产生率的垂直分布与有机酸含量的垂直分布一致。水稻植株对甲烷产生率有巨大影响，即种植水稻比不种水稻甲烷产生率显著增加。稻田土壤排到大气中的甲烷不到其产生量的２０％。     

亚热带红壤性稻田的甲烷排放

亚热带红壤性稻田的甲烷排放量为５５．２３９／ｍ２·ａ．不同年度间有差异；在年度内（水稻生长季节）亦有差异．以８月排放最多，其余月份依其排放量的顺序是７月，６月，５月，９月，１０月．甲烷排放率的日变化有规律性，１６时前后出现最大值，６时左右出现最小值，呈单峰型，日变化幅度与天气有关，季节变化比较复杂，无规律性，在不同年度、不同稻季（早、晚季），其变化也不一致．稻田甲烷排放与水稻生产和生长密切相关，水稻的种植和生长是稻田甲烷排放的基础和根源．     

免耕稻-鸭复合系统减少甲烷排放及其机理研究

以免耕不养鸭和翻耕不养鸭稻田为参照，研究了免耕稻-鸭复合系统中甲烷排放的日变化和季节变化以及稻-鸭复合系统中土壤氧化还原特性对甲烷排放的影响。结果表明：稻田甲烷排放通量日变化与日气温变化基本趋于一致。在水稻分蘖盛期和孕穗期，免耕养鸭稻田甲烷排放通量明显低于免耕不养鸭和翻耕不养鸭稻田，3者之间甲烷排放通量大小差异白天明显，夜间较小。在水稻分蘖盛期、孕穗期和齐穗期，免耕养鸭稻田水中溶解氧含量比免耕不养鸭和翻耕不养鸭稻田提高38．4％～44．7％。由于鸭子的活动，免耕养鸭稻田的氧化还原电位分别比免耕不养鸭和翻耕不养鸭稻田高11和18mV。而翻耕不养鸭稻田的还原物质总量分别是免耕养鸭稻田和免耕不养鸭稻田的4．17～12．34倍和3．26～7．02倍，其亚铁离子含量也明显高于后2者，表明翻耕使土壤还原程度增强，进而促进了稻田甲烷的排放。相关分析表明，免耕养鸭稻田氧化还原电位与还原物质总量、活性还原物质总量和亚铁离子含量呈极显著负相关，也与稻田甲烷排放通量呈负相关，但未达显著水平。     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

Representation of the world's biophysical conditions by the global protected area network

Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network.     

Quantitative composition of the defensive secretion ofBledius species (Coleoptera: Staphylinidae: Oxytelinae) is adapted to naturally occurring predators

Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in either-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.     

Democracy versus development: New urban debates

The politics of development includes subtexts of choice, as underpinned by community consensus (or lack of it), against the larger backdrop of a liberal democracy, with its intricate power structures that influence the choice of concepts and often lead to complicity rather than consent. A dilemma exists between the understanding of field-level practitioners and that of academics, whose understandings of progress differ. Progress can (and often does) imply long-term change across generations whereas development is often more a matter of crisis management and delivering tangible results to end-users. This makes it a bone of contention across political systems, irrespective of local or global dynamics. Development can emerge as a tool to be wielded for power and further political mileage at the expense of progress. Progress cannot be studied as a counterpoint to development as the sense of history is often missing in development interventions. Development tends to be piecemeal as its very logic often stems from the rationale of power. This is not to suggest, however, that development is only about politics; it is definitely more than the politics of everyday life and involves all of civil society that requires its critical and immediate attention. In this sense, it has become a priority for politicians with an underlying agenda designed to out-manouevre dissent and all statements of protest.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

A framework to measure the wildness of managed large vertebrate populations

As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.     

Sexual Predators,Energy Development,and Conservation in Greater Yellowstone

Abstract: In the United States, as elsewhere, a growing debate pits national energy policy and homeland security against biological conservation. In rural communities the extraction of fossil fuels is often encouraged because of the employment opportunities it offers, although the concomitant itinerant workforce is often associated with increased wildlife poaching. We explored possible positive and negative factors associated with energy extraction in the Greater Yellowstone Ecosystem (GYE), an area known for its national parks, intact biological diversity, and some of the New World's longest terrestrial migrations. Specifically, we asked whether counties with different economies—recreation (ski), agrarian (ranching or farming), and energy extractive (petroleum)—differed in healthcare (gauged by the abundance of hospital beds) and in the frequency of sexual predators. The absolute and relative frequency of registered sex offenders grew approximately two to three times faster in areas reliant on energy extraction. Healthcare among counties did not differ. The strong conflation of community dishevel, as reflected by in‐migrant sexual predators, and ecological decay in Greater Yellowstone is consistent with patterns seen in similar systems from Ecuador to northern Canada, where social and environmental disarray exist around energy boomtowns. In our case, that groups (albeit with different aims) mobilized campaigns to help maintain the quality of rural livelihoods by protecting open space is a positive sign that conservation can matter, especially in the face of rampant and poorly executed energy extraction projects. Our findings further suggest that the public and industry need stronger regulatory action to instill greater vigilance when and where social factors and land conversion impact biological systems.     

Cost‐effective conservation of an endangered frog under uncertainty

How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.     

Comparison of the insecticidal effects of water extracted and intact aromatic plants onAcanthoscelides obtectus,a bruchid beetle pest of kidney beans

Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.