衡阳地区西葫芦品种比较试验

在衡阳地区对7个西葫芦品种进行了品种比较试验.结果表明:参试的7个品种在早熟性方面明显优于对照品种,其中湘葫一号和金船46号西葫芦比对照增产10%以上,2个品种产量均高达为6 800 kg·(667 m2)-1;世龙翡翠、玉菇39号西葫芦、优玉西葫芦比对照增产在5%~10%之间.湘葫一号、湘葫二号、玉菇39号、美国如意西葫芦比对照品种的植株发生病毒病和白粉病少,属于高抗病性品种.该7个品种综合性状优良,值得大面积推广应用.     

保水剂对侧柏容器苗根际土壤微生物种群结构及干旱适应能力的影响

为更好地将保水剂应用到干旱山地的容器苗造林中,以丙烯酰胺-丙烯酸钾交联共聚物型保水剂作为供试材料,设置育苗时(NS)和造林时(AS)各加4.0 g保水剂的两种保水剂应用方式,利用传统的平板计数法和现代的末端限制性片段长度多态性分析(Terminal restricti on fragment length polymorphism,T-RFLP)技术,研究NS和AS对侧柏容器苗造林一年后根际土壤微生物种群结构及对侧柏干旱适应能力的影响.结果表明:保水剂可显著提高侧柏根际土壤细菌、真菌的数量和微生物量碳、氮的含量,且NS处理根际土壤的细菌数量和微生物量碳分别比AS处理提高21.65%和8.04%;保水剂及其应用方式对造林初期侧柏根际土壤的细菌群落结构产生较大影响,保水剂显著增加了根际土壤中细菌群落结构的多样性,NS处理具有最高的丰富度指数、多样性指数和最低的优势度指数;此外,同对照相比,NS处理还显著提高了侧柏容器苗的造林成活率、叶片的净光合速率和相对含水量,降低了相对电导率;同AS处理相比,NS处理的造林成活率和叶片相对含水量分别提高了11.64%和8.33%,而相对电导率降低(降低12.19%).综上说明,保水剂通过改善侧柏容器苗根际土壤的微生物种群结构而提高植物的干旱适应能力,利用添加保水剂的容器苗造林具有更好的应用效果.     

滴灌覆膜对杨树硬枝扦插育苗生长效应影响

以渤丰3号杨、中辽1号杨、中绥12号杨、辽宁杨4个不同无性系为供试材料,采用滴灌覆膜和漫灌两种杨树硬枝扦插育苗方式,以常规漫灌育苗为方式对照,结合滴灌覆膜和漫灌育苗苗木的地径、苗高、叶面积、叶绿素含量、物候期、成活率、质量等方面进行比较研究.试验结果表明,滴灌覆膜苗高和叶面积值高于对照,苗高高于对照21.6%,叶面积高于对照6.8%;地径和叶绿素含量低于对照,地径低于对照2.1%,叶绿素低于对照6.1%;萌动时间和展叶时间早于对照,与对照相比平均提前7 d;成活率、合格苗率和一级苗率高于对照,成活率高于对照23.9%,合格苗高于对照34.5%,一级苗高于对照42.6%.滴灌覆膜杨树扦插方式有利于苗高的增长,能够有效提高苗木的质量.     

染织排水对日本青鳉幼鱼和胚胎的毒性效应

采用日本青鳉幼鱼及胚胎暴露评估染织排水的毒性效应.4个测试水样采自染织工厂排水口.96 h急性毒性试验表明:1和2号水样对幼鱼急性毒性效应不明显,3和4号水样对幼鱼具有急性毒性效应,毒性单位分别为0.47、0.53、9.93和1.68TUa,1和2号水样为微毒,3号水样为中毒,4号水样为低毒.14 d胚胎幼鱼慢性毒性试...     

厌氧-好氧一体式折流板反应器处理淀粉废水的启动运行

采用厌氧-好氧一体式折流板反应器,处理马铃薯淀粉废水,以淀粉废水排放口底泥作为接种污泥,可以实现快速启动。启动过程的结果表明:在温度为2 5℃～35℃,总水力停留时间(HRT)为5 4h ,容积负荷从0 .5kg/ (m3 ·d)逐渐升高到3.0 8kg/ (m3 ·d)时,第11d就将反应器启动成功,前3级厌氧反应器总的去除率达到75 % ,厌氧-好氧一体式折流板反应器总的去除率达到96 %。而后逐渐提高容积负荷,当容积负荷为10 .0kg/ (m3 ·d)时,COD去除率最高为96 % ,出水水质达到或接近国家污水排放二级标准(GB 8978- 96 )。     

三唑磷在水稻籽粒中动态变化及分布特征

采用田间试验的方法,研究了不同品种水稻(内2优6号和秀水09)抽穗前,经不同浓度三唑磷(2250 m.lha-1和4500 m.lha-1)处理一次后,三唑磷在水稻籽粒中动态变化及其分布特征.试验结果表明,水稻籽粒中三唑磷含量随时间延长先增加后降低,所测数据中最高浓度出现在施药后第21天.三唑磷在水稻籽粒中的分布特征为稻壳胚乳淀粉组织糠,三唑磷主要分布在稻壳和糠中,两者总共承载了近90%的含量.其中喷施浓度为2250 m.lha-1时,内2优6号和秀水09精米中三唑磷的含量分别为0.024 m.gkg-1和0.019 m.gkg-1,均符合国家限量标准.     

桉树成林无性系转化试验研究

通过近两年的桉树成林无性系转化试验,结果表明,桉树成林无性系之间扦插成活率差异显著:夏季扦插成活率高于秋季,且生根时间短,便于管理;不同浓度的ABT生根粉对桉树扦插成活率有极显著影响,以ABT(1号)生根粉100PPM浸泡3小时为最佳;不同年龄的枝条对桉树扦插成活率有显著影响,其中以当年生半木质化枝条扦插成活率为最高.     

黄花菜根水浸提液对大白菜化感作用的初步研究

以黄花菜根为试材,研究不同浓度水浸提液对不同品种大白菜种子萌发和幼苗生长的影响,对黄花菜根化感物质的作用进行研究.试验结果表明:不同浓度黄花菜根水浸提液对不同品种大白菜(精选83-1和迷你黄)种子萌发和幼苗生长的作用效果不同.当浓度为10 mg/m L,15 mg/m L,20 mg/m L时,对于精选83-1和迷你黄的化感作用不同,有的表现为促进作用,有的表现抑制作用.高浓度(25 mg/m L)对于精选83-1和迷你黄则全部表现为抑制作用,且浓度越高抑制作用越明显.图5,表2,参12.     

扎龙湿地土壤微生物群落结构的季节变化特征

运用磷脂脂肪酸(PLFA)法研究扎龙湿地各季节土壤微生物群落结构和多样性.结果表明:不同季节土壤中共检测到29(春)、30(夏)、29(秋)和27(冬)种PLFA,其中含量最高的PLFA分别为16:0(16.49%)、18:1ω9c(17.41%)、18:1ω9c(20.48%)和18:2ω6,9(26.16%).季节变化对一般性细菌、G~+菌、G~-菌、真菌、放线菌和总PLFAs有显著影响(P0.05),除真菌外均表现为春季最高、冬季最低,而真菌则为冬季最高、春季最低.香农-威纳多样性指数和Mc Intosh指数在春季最高,Simpson指数则在冬季最高.主成分分析(PCA)表明,第1主成分和第2主成分共解释土壤微生物群落结构总变异的87.6%,不同季节间土壤微生物群落结构存在显著差异.冗余分析(RDA)表明,放线菌和G~+菌与土壤有机质、总氮、速效氮和速效钾呈显著正相关,G~-菌与速效磷呈显著正相关,真菌和一般性细菌与土壤pH呈显著正相关.扎龙湿地微生物群落结构的季节波动与土壤养分状况密切相关,研究结果可为扎龙湿地生态功能恢复提供科学依据.     

硒对不同品种茶树土壤酶活性及硒含量的影响

为探明硒与不同品种茶树土壤酶活性变化规律之间的关系,采用盆栽试验方法,设置8个处理,分别为:对照(CK,即不添加硒),2、4、8、10、15、20、30 mg·kg~(-1)等7个Se处理水平,研究不同处理水平硒对不同季节茶树(Camellia sinensis)品种(福鼎大白和南江1号)土壤酶活性和硒含量的影响,为不同品种茶树土壤合理施用硒肥提供一定的科学依据。结果表明,春季硒对福鼎大白土壤脲酶活性有刺激作用,在硒处理水平为30 mg·kg~(-1)时表现出最大值(2.77 mg·g~(-1)·d~(-1));低水平硒对春季福鼎大白土壤蔗糖酶活性刺激作用明显,硒处理水平为4 mg·kg~(-1)时,蔗糖酶活性最高,为12.63 mg·g~(-1)·d~(-1),南江1号土壤蔗糖酶活性在硒处理水平为10 mg·kg~(-1)时表现出最大值,为12.18 mg·g~(-1)·d~(-1);夏季硒对2个品种茶树土壤脲酶、蔗糖酶活性抑制作用明显;春、夏两季硒对土壤酸性磷酸酶活性均表现为抑制作用,且均在硒处理水平为30 mg·kg~(-1)时抑制作用明显,春季福鼎大白和南江1号土壤酸性磷酸酶活性分别较对照降低了32.8%和14.7%,夏季分别降低了36.8%和29.5%。南江1号夏季土壤脲酶、蔗糖酶活性与硒处理水平均呈显著负相关(相关系数分别为-0.758和-0.768)。不同水平硒处理均提高了2个品种茶树土壤硒含量,春季福鼎大白和南江1号土壤硒质量分数分别较对照提高了83.2%和83.1%,夏季分别提高了86.3%和85.2%,且春、夏两季福鼎大白土壤硒质量分数均低于南江1号。综上,硒对土壤酶活性的影响随硒处理水平、茶树品种和酶类型的不同而异,土壤硒质量分数也随硒处理水平和茶树品种的不同而异。     

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.     

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.     

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.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture