黑色岩系成壤过程中镉和硒的形态转变与迁移特征

[目的] 黑色岩系含有高量的镉和硒,为明确其在风化成土过程中,岩石镉和硒的形态转变和释放对周围生态环境产生影响。[方法] 在浙西北寒武统荷塘组地层的黑色岩系分布区,通过沿地形不同部位(丘陵上坡、丘陵中坡、丘陵下坡、丘间谷底和河谷阶地)采集土壤剖面分层土样,探讨黑色岩系风化成土及其风化物迁移过程中镉和硒的数量与形态转变规律。[结果] 从母岩经母质到土壤,土壤总镉和总硒均呈下降趋势。黑色岩系风化物镉和硒损失随沿丘陵坡地向下迁移搬运距离增加而增加,其中,由坡积物演变为洪积物的过程中,镉和硒的损失大于由残积物演变为坡积物的损失。从风化物中流失的镉和硒以流水扩散方式对下游河流冲积物发育表土镉和硒含量产生影响,但影响程度随距离增加而减小。随着风化物搬运距离增加和土壤的演变,发生碳酸盐结合态镉和残留态镉向水溶性镉、交换性镉、有机质结合态镉、氧化物结合态镉转变,残留态硒逐渐活化转变为交换性硒、有机质结合态硒、氧化物结合态硒。土壤水溶性镉、交换性镉(硒)、有机质结合态镉(硒)呈现向地表增加的趋势;硒的有机富集及表土富集现象比镉更为明显。[结论] 黑色岩系风化不仅可通过残留方式直接影响其分布区土壤镉与硒的含量,也可通过流水扩散方式影响周边地区土壤镉和硒的含量。     

Dermocystid infection in Japanese fire-bellied newt,Cynops pyrrhogaster

Here, we report details of a new infectious disease in wild-caught Japanese fire-bellied newts (Cynops pyrrhogaster), a Near Threatened species. Skin lesions consisting of numerous masses were found in the animals near Lake Biwa, Shiga Prefecture, Japan. The gross appearance of the skin lesions showed blister-, cyst-, and/or tumor-like morphology. Various sizes of skin lesions were observed on their entire body surface. Histologically, spherical basophilic cysts, including numerous spores, were observed in the dermis layer. Ultrastructural analysis indicated the presence of main bodies of flagellated zoospores within the spores. While 18s rRNA gene sequencing indicated that the skin lesions were due to dermocystid infection. To our knowledge, this is the first report of dermocystid infection in this amphibian in Japan. Further studies are needed to prevent epidemics and to establish diagnostic and treatment methods.     

甘肃天水苹果黑星病年消长动态调查及防治药剂筛选

为明确苹果黑星病在甘肃天水年消长动态、发病规律及筛选高效防治药剂,采用田间调查苹果黑星病在生长季不同时期的消长动态及发病规律,同时开展田间药剂筛选试验。结果表明,天水地区苹果黑星病在5月中旬开始侵染,7月底达到第一次发病高峰,8月上中旬病情发展缓慢,8月下旬至9月下旬,病菌又一次侵染秋梢,达到第二次发病高峰,之后进入病菌越冬预备期。因此,药剂防治应在叶片显症前5月上中旬开始,6-7月份和9月上旬是防治苹果黑星病的关键时期,采用本试验筛选的25%苯甲?吡唑酯SC1000倍液、25%戊唑?异菌脲SC2500倍液、40%氟硅唑EC1500倍液和20%烯肟?戊唑醇SC1000倍液,防效达81.49%-91.57%;12.5%烯唑醇WP1500倍液、25%吡唑醚菌酯SC800倍液、12.5%腈菌唑EC1000倍液和40%咪鲜胺EW800倍液,防治效果达74.57%-77.15%,防治时采用保护性杀菌剂和治疗性杀菌剂交替施用。综上所述,本试验明确了苹果黑星病的年消长动态、发病规律、筛选出了高效防治药剂,为苹果黑星病的有效防控提供了理论依据和技术支撑。     

南京裂爪螨丝膜数量消长及空间格局时序动态

林间调查分析结果表明：①南京裂爪螨丝膜数量消长与该螨种群一致，在年周期中有2个高峰期，分别是3月和9—11月，4—8月处于较底的水平；②丝膜数量与气温呈极显著相关(r＝-0．6187)；②一年中大多数时期南京裂爪螨丝膜呈聚集分布，仅5—8月呈均匀分布或接近于均匀分布，并具有明显的高度聚集分布—均匀分布—低度聚集分布—高度聚集分布周期；④丝膜的分布C值与气温及降雨量呈显著相关(r＝—0．5403，—0．4530)。     

敖汉旗沙地樟子松造林试验

为探讨樟子松在敖汉旗沙地的适生能力，进行了樟子松沙地造林试验，结果表明，24年生的樟子松林，表现基本稳定，生长较快，年平均树高生长量达0．22－0．38m，胸径生长量达0．34－0．59cm，比油松和小叶杨的生长量大。调查研究发现，影响樟子松林生长的主要因素是，当地的降水量较低，在干旱年分林分出现水分亏缺；部分地区的土壤下层有白土间层，水分和养分的含量低；有些林分密度偏大，林分出现枯死现象。     

春小麦皮蓟马田间发生规律研究

小麦皮蓟马在本地1年发生1代,以成虫在田边杂草上越冬。每年的5月末春麦田中始见越冬成虫,6月中旬为越冬成虫发生高峰期,7月初越冬成虫消失。6月23日左右始见若虫,7月中旬为若虫发生危害高峰期,而后若虫数量逐渐减少。7月中旬左右出现第一代成虫,随小麦成熟陆续转移至田边杂草上为害并越冬。     

Removal of nonnative fish results in population expansion of a declining amphibian (mountain yellow-legged frog, Rana muscosa)

The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. The objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant R. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulation structure in each watershed as R. muscosa from expanding populations in fish-removal lakes dispersed to adjacent habitats. At all three fish-removal lakes, R. muscosa population densities increased significantly following the removal of predatory fish. The magnitude of these increases was significantly greater than that observed over the same time period in R. muscosa populations inhabiting control lakes that remained in their natural fishless condition. Following these population increases, R. muscosa dispersed to adjacent suitable (but unoccupied) sites, moving between 200 and 900 m along streams or across dry land. Together, these results suggest that large-scale removal of introduced fish could result in at least partial reversal of the decline of R. muscosa. Continued monitoring of R. muscosa at the fish-removal sites will be necessary to determine whether the positive effects of fish eradication are sustained over the long-term, especially in light of the increasingly important role played by an emerging infectious disease (chytridiomycosis, caused by Batrachochytrium dendrobatidis) in influencing R. muscosa populations.     

Emerging disease and population decline of an island endemic, the Tasmanian devil Sarcophilus harrisii

We present evidence that Devil Facial Tumour Disease (DFTD) is an emerging disease that is now widespread and constitutes a serious threat to the Tasmanian devil Sarcophilus harrisii. This species, the world’s largest extant marsupial carnivore, is endemic to Tasmania. DFTD is a cancerous disease found exclusively in wild devil populations, and appears to be consistently fatal to afflicted individuals. We draw on data from a wide range of sources and locations across Tasmania, acquired through trapping, spotlighting and public observation, to assess the impact and distribution of this disease. The dramatic tumours characteristic of DFTD were first reported in 1996. There were no reports of these signs in any of more than 2020 individuals trapped previously. Since 1996, DFTD has been histologically confirmed in individuals from 41 separate sites, covering 32 930 km² (51%) of mainland Tasmania. From the few sites for which timing of DFTD emergence can be estimated, there is evidence for geographical spread of the disease. Of 147 devils with DFTD-like signs, at least 140 were sexually mature. Proportion of animals displaying signs at any one site reached up to 83% (15/18) of trapped adults. Spotlighting surveys and trapping indicated a significant local association between population decline and date of first report of DFTD. In the region where the disease was first reported, mean spotlighting sightings declined by 80% from 1993-1995 to 2001-2003. On the basis of the threat posed by DFTD, the devil has been listed as a threatened species in Tasmania, and nominated for listing at national level.     

Evidence for disease-related amphibian decline in Colorado

The recent discovery of a pathogenic fungus (Batrachochytrium dendrobatidis) associated with declines of frogs in the American and Australian tropics, suggests that at least the proximate cause, may be known for many previously unexplained amphibian declines. We have monitored boreal toads in Colorado since 1991 at four sites using capture–recapture of adults and counts of egg masses to examine the dynamics of this metapopulation. Numbers of male toads declined in 1996 and 1999 with annual survival rate averaging 78% from 1991 to 1994, 45% in 1995 and 3% between 1998 and 1999. Numbers of egg masses also declined. An etiological diagnosis of chytridiomycosis consistent with infections by the genus Batrachochytrium was made in six wild adult toads. Characteristic histomorphological features (i.e. intracellular location, shape of thalli, presence of discharge tubes and rhizoids) of chytrid organisms, and host tissue response (acanthosis and hyperkeratosis) were observed in individual toads. These characteristics were indistinguishable from previously reported mortality events associated with chytrid fungus. We also observed epizootiological features consistent with mortality events associated with chytrid fungus: an increase in the ratio of female:male toads captured, an apparent spread of mortalities within the metapopulation and mortalities restricted to post metamorphic animals. Eleven years of population data suggest that this metapopulation of toads is in danger of extinction, pathological and epizootiological evidence indicates that B. dendrobatidis has played a proximate role in this process     

桂花上桔全爪螨种群消长规律及与环境因子的关系

本文研究了结全爪螨种群在桂花上的消长规律及与环境因子的关系。桂花桔全爪螨种群一年中有４个高峰，其为害最高峰在４月中旬～５月上旬及５月中旬～６月上旬，环境因子温度、相对湿度、光照时数、降雨量及天敌对卵量影响较小，对幼、葳、成螨的数量影响较大，其中天因子的影响尤为显著，螨量与光照时数呈负相关的关系。螨量与环境因子的逐步回归方程：ｙ５＝０．２５６２＋０．０５８４ｘｒ２－０．１３２ｘｓ１＋０．１１７２ｘ３