Adjustments in leaf water relations of mangrove (Avicennia germinans) seedlings grown in a salinity gradient

We used pressure-volume analysis and dewpoint hygrometry to determine leaf water relation parameters of mangrove (Avicennia germinans L.) seedlings grown at salinities of 0, 8, 20 and 32 per thousand. Seedlings responded to an increase in salinity from 0 to 32 per thousand by an increase in leaf succulence as reflected in an increase in leaf water content per unit area from 300 to 360 g m(-2). Additionally, osmotic potential at full turgor decreased from -2.3 to -3.5 MPa and osmotic potential at zero turgor decreased from -2.7 to -4.3 MPa. Cell elasticity decreased as salinity increased from 0 to 32 per thousand, as indicated by a progressive increase in volumetric modulus of elasticity from 19 to 27 MPa. Increased leaf succulence enabled leaves to sequester large amounts of solutes without adversely increasing cell osmotic pressure. On the other hand, osmotic adjustment facilitated turgor maintenance as water potential diminished. Salinity-induced decreases in tissue elasticity generated greater water potential differences between leaves and soil under saline conditions than under non-saline conditions.     

Variations in water use by a mature mangrove of Avicennia germinans, French Guiana

? In the tropical intertidal zones, little is known on water uptake by mangroves. Transpiration rates are generally measured at leaf level, but few studies exist on water use at tree or stand levels.

? The objective of this study was to measure sap flow in trees of different sizes to appreciate the range of variation in water use that may exist in a site dominated by 80% mature Avicennia germinans.

? The results showed that from the dry to the wet season the mean water use increased from 3.2 to 5.3 dm³ d^?1 in small trees (DBH ～ 13 cm), from 11.5 to 30.8 dm³ d^?1 in medium trees (～24 cm) and from 40.8 to 64.1 dm³ d^?1 in large ones (～45 cm).

? Sapwood remained active up to a depth of 8 cm with radial variations within the stem. Weak correlations were obtained with VPD and net radiation.

? This study confirmed that transpiration was larger under low levels of salinity. Water use at stand level (～1900 living stems ha^?1) was estimated to be in the range of 5.8 to 11.8 m³ ha?1 d^?1 according to the season.

     

Traditional agroforestry systems and biodiversity conservation in Benin (West Africa)

In the past, the conservation of biodiversity has been mostly understood in terms of the management of protected areas and natural forests, ignoring the possible role of farm areas and the ways through which rural communities have promoted biodiversity in their subsistence agricultural production systems. The present study focused on the floristic diversity within traditional agroforestry parkland systems around the Pendjari Biosphere Reserve in Benin and showed the diversity of tree species in the area as well as socio-economic factors which affect the practice of this farming system. We used questionnaires and interviewed a total of 118 households to collect data. Respondents were interviewed on their farms and during the interview; we inventoried the number of tree on the farm and determined the farm size. Twenty-one tree species belonging to 14 botanical families were recorded during the surveys and the average stand density of the woody component of farmlands was 7.97 ± 5.43 stems/ha. A number of both native and exotic tree species occurred in the parkland agroforestry systems with dominance of indigenous tree species. Species richness varied with the size of household where households with small land holding conserve more tree species in their field than households with large land holdings. 64% of households surveyed were making deliberate efforts to plant tree species on their farmlands. The most important reasons which determined household ambitions to conserve woody species on farmland were tree products contribution to food and medicine. Results also showed that respondents who noticed that trees were decreasing in the wild conserve more tree species on their farmlands. This research highlights the role of traditional agroforestry practices to support tree species richness and provides evidence of the farms’ role as biodiversity reservoirs.     

The role of land tenure in agroforestry: lessons from Benin

In this article the relationship between land tenure and agroforestry is analysed drawing on a case study from Benin. It is argued that tenants, the landless and the majority of women are disadvantaged compared with landowners in terms of their ability to adopt agroforestry systems. This is due to a lack of land resources, tenure insecurity and restrictions in planting perennial crops. State interventions and conflicts between farmers and pastoralists further limit land tenure security of the rural population and thus reduce the willingness of peasants to invest on a long-term basis and to protect natural resources. The article concludes with some implications for policy and project interventions in the field of land tenure systems.

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Résumé Dans cet article, les relations entre droit foncier et agroforesterie sont analysées dans le cas du Bénin. Le fait que les locataires, les paysans sans terre et la plupart des femmes sont désavantagés par rapport aux propriétaires parce qu'ils ne sont pas en mesure d'adopter des systèmes agroforestiers est mis en evidence. Cela est dû au manque de ressources foncières, à l'incertitude de l'utilisation de la terre et aux restrictions sur la plantation des cultures pérennes. Des interventions étatiques et des conflits fonciers entre agriculteurs sédentaires et éleveurs restreignent la sécurité foncière de la population rurale et réduisent la disposition des paysans à investir à long terme et à protéger les ressources naturelles. A la fin de l'article les conclusions pour des interventions politiques et pour la planification des projets dans le domaine du droit foncier sont identifiées.

     

Biodiversity and socioeconomic factors supporting farmers' choice of wild edible trees in the agroforestry systems of Benin (West Africa)

Wild edible trees are expected to play a significant role in the crop diversification programs and agroforestry development in Africa. In the present study, the diversity of wild food species and socio-economical factors that support farmers' choice for the species used in these systems were assessed. A number of selected sites in each of the 3 climatic zones of Benin were surveyed. Data were collected through a field exploration and a semi-structured survey among 435 selected households throughout the country, using a questionnaire. The most culturally important species ranked by locals were determined for each climatic zone and the relations between the targeted species in traditional agroforestry systems and the reasons which support peasants' choices were described through a Principal Component Analysis. A total of 43 wild edible trees were found in the traditional agroforestry systems of Benin during the survey. Traditional agroforestry systems in the Guineo-Congolian zone turned out to be the most diversified with 29 species followed by the Sudanian zone with 22 species and Sudano-Guinean zone with 16 species. The most culturally important wild edible trees in traditional agroforestry systems in the Guineo-Congolian zone were different from those identified in Sudanian and Sudano-Guinean zones. Three main reasons that support peasants' ambition to conserve or to grow wild edible trees in their field were: their contribution to food, their use in traditional medicine and ceremonies and the farmers' perception of their availability in natural vegetation.     

Spatial distribution and impacts of climate change on Milicia excelsa in Benin,West Africa

African teak(Milicia excelsa(Welw.) C.C.Berg) is an endangered multi-use species.Understanding the impact of climate change on the distribution of this species may improve the ability to anticipate or recognize its decline or expansion and to take appropriate conservation measures if necessary.Ecological niche modeling was projected in geographical space to study the current and future distribution of M.excelsa in Benin.MaxEnt was used to estimate the potential geographic distribution of the species under two Representative Concentration Pathways(RCP).Miroc 5 summaries and two RCP 4.5 and RCP 8.5 scenarios were used as predictor variables for projections of the geographic potential of this species.The performance of the model was assessed by the area under the curve(AUC),true skill statistics(TSS) and partial receiver operating characteristics(Partial ROC).From the results,M.excelsa was more a secondary species in the Guinean climatic zone and part of the Sudanian-Guinean and Sudanian climatic zone.The projections show a significant decrease in suitable habitats for the species from the two RCP scenarios.Only a part of the Guinean climatic zone remained suitable and few protected areas will conserve in situ M.excelsa.For the sustainable conservation of M.excelsa,it is essential to strengthen the protection of sacred forests located in the Guinean climatic zone.     

雷州半岛白骨壤种群直径分布规律

在林分生长模型研究中,选择描述林分直径分布的函数至关重要。以雷州半岛白骨壤种群为研究对象,对其开展直径调查,所得数据以偏度、峰度为指标,并运用正态分布、Weibull分布和Gamma分布等3种概率密度函数进行参数拟合检验,分析白骨壤种群的直径分布特征。研究结果表明:雷州半岛白骨壤种群以中小径阶居多,其偏度和峰度均大于0,直径分布曲线为左偏态,分布曲线比较陡峭,呈尖峰态;正态分布和Weibull分布的拟合效果较差,而Gamma分布则具有较好的拟合效果;通过建立Gamma分布参数预估方程,可预测林分各个径阶的株数及其动态变化。通过对雷州半岛白骨壤种群直径分布规律的调查研究,以期为雷州半岛白骨壤群落的经营管理以及利用提供一定的参考。     

Eutypella canker of maple: first report from Germany and situation in Austria

Eutypella canker of maple, caused by Eutypella parasitica (which is native to North America), is reported for the first time from Germany. From 2013 to 2015, this perennial canker disease was recorded on 105 maple trees in Munich. Six maple species were affected: Acer pseudoplatanus, A. campestre, A. platanoides, A. cappadocicum, A. heldreichii ssp. trautvetteri and A. hyrcanum. Occurrence on the latter three species represents new host records for E. parasitica. In Austria, Eutypella canker was newly discovered on two trees at a second locality in 2011, and it is now known to occur on seven A. pseudoplatanus trees at two localities, which are separated nearly 150 km. A. pseudoplatanus was the most frequent host of E. parasitica in Munich and Austria, which is in agreement with previous studies in Europe. The identity of the causative pathogen as E. parasitica was verified by ITS rDNA sequencing of fungal cultures obtained from cankers in Munich and at both Austrian localities. The presence of large and old cankers in both countries suggests that introduction of E. parasitica dates back a long time, probably several decades. The new records of Eutypella canker in Germany and Austria show that the disease is more widely distributed in central Europe than previously recognized.     

福建漳江口红树林病害初步调查

通过对福建漳江口红树林湿地国家级自然保护区红树林叶部病害进行调查,并采集病害标本分离鉴定,经初步分类研究,叶面真菌病害计有交链孢属、镰刀菌属、盘多毛孢属、曲霉属、青霉属等2纲3目4科5属。其中白骨壤的病害种类最多,桐花树受盘多毛孢菌危害最严重。     

白骨壤酸性多糖的分离纯化及抗补体活性研究

采用热水浸提,乙醇沉淀,超滤,三氯乙酸脱蛋白,DEAE-纤维素柱层析脱色,再经DE-AE-Sepharosefastflow和SephacrylS-400层析,从白骨壤树枝分离纯化得到多糖化合物HAM-3-Ⅱb-Ⅱ,经高效凝胶过滤色谱法和比旋光度测定法鉴定为均一性组分,其重均相对分子质量(Mw)为105200,比旋光度为 27.54°。糖组成分析表明它为酸性杂多糖,主要由半乳糖醛酸、阿拉伯糖、半乳糖和鼠李糖组成。紫外光谱表明其不含核酸和蛋白质等杂质成分;红外光谱证实它是一种酸性果胶类多糖,以α型差向异构为主;补体结合实验表明,该多糖通过经典途径和替代途径共同作用产生显著的抗补体活性,并呈一定的剂量效应关系。     

广东省红树林生态系研究展望

广东省是我国红树林分布面积最大和台风多的省区,也是国际候鸟迁徙路线上停歇和越冬的主要站点,在减灾防灾、生物多样性和污染物生态修复等方面有极其重要的研究意义。因此,广东省红树林生态系研究要着重解决广东省现有红树林的生物多样性调查、生态功能评估、生态系统经营、大量红树果实加工利用、沿海困难滩涂与堤岸红树林营造等技术问题,为其红树林生态系恢复与管理及其红树林生态系资源的可持续利用提供技术支撑。     

First report on Bursaphelenchus sexdentati (Nematoda: Aphelenchoididae) in Israel

This is the first report and characterization of Bursaphelenchus sexdentati and the first official report of the presence of the genus Bursaphelenchus in Israel. This species was isolated from Orthotomicus erosus (Coleoptera: Scolytinae) found on Pinus halepensis in the Judean foothills in Israel. Nematodes collected from insect galleries were reared on fungal cultures and identified based on morphological diagnostic characters for the genus Bursaphelenchus. Sequencing analyses of the Internal Transcribed Spacer (ITS) region, small subunit (SSU) and large subunit (LSU) of ribosomal DNA confirmed the identification of this nematode species collected from wood and directly from the insect body.     

Temporal changes in nitrogen acquisition of Japanese black pine （Pinus thunbergii） associated with black locust （Robinia pseudoacacia）

The alien woody legume, black locust(Robinia pseudoacacia), has invaded Japanese black pine(Pinus thunbergii) forests located in Japan's coastal plain and hill regions where gaps are formed in pine forests after nematode infestation. Nitrogen fixation by legumes accelerates N cycling in forest ecosystems. We studied temporal change in the annual tree-ring resolution N stable isotope composition(δ15N, a per mil deviation of δ15N/14 N ratio, relative to atmospheric N2δ15N=0‰) at two natural locations of Japanese black pine forest with black locust that differed in the time since black locust establishment(Shohnai in northeast and Kita-Kyushu in southwest Japan). Analyzed tree-rings covered the period from 1990/1992 to 2009. N acquisition by Japanese black pine from black locust N input to the soil was evidenced by temporal shifting of N stable isotope composition on the annual pine tree rings. With progressive development of the forest stand, δ15N values of earlier tree-rings δ15N of-5‰) from black pine associated with black locust shifted towards values similar to those of black locust δ15N values nearly to-1‰), which suggests acquisition of N by N2 fixation(Shohnai site). In contrast, in a forest where black locust had settled for two or three generations, in a black pine stand(Kita-Kyushu site), longer periods of N enrichment in the soil were reflected in the elevated tree-ring δ15N values of newly established black pine trees. Based on tree-ring δ15N data from the Shohnai site, we determined that about 10 years after black locust establishment, soil N had already been enriched by black locust N, this, in turn, contributed to N fertilization of surrounding trees in mixed stands.     

First report of Sphaeropsis canker on cypress in South Africa

In this study a Sphaeropsis sp. is recorded as causing cankers on cypress in South Africa. These cankers are either found alone or on trees which are infected with the well-known cypress canker pathogen, Seiridium unicorne. When the two fungi occurred together, lesions could not be distinguished from each other, although the greater number of lesions were caused by the Sphaeropsis sp. The fungus appears to be identical to that described as Sphaeropsis sapinea f.sp. cupressi, in Israel, which is a fungus very different from the pine pathogen, Sphaeropsis sapinea. Pathogenicity tests showed that the Sphaeropsis sp. is significantly more pathogenic to Cupressus lusitanica than to Pinus roxburgii and Pinus elliottii. S. sapinea was pathogenic only to the Pinus spp. tested, and not to C. lusitanica. In contrast, the cypress pathogen Seiridium unicorne, was pathogenic to C. lusitanica and also to the two Pinus spp. tested.     

A new species,first report of a male and new distributional records for five species of Oligosita Walker(Hymenoptera:Trichogrammatidae) from China

Seven species of the genus Oligosita, a wellknown cosmopolitan genus of the family Trichogrammatidae that comprise egg parasitoids of coleopteran, hemipteran, lepidopteran and thysanopteran insects, are reviewed. Oligosita xinyangensis sp. nov.(Hymenoptera, Trichogrammatidae) is described in detail and illustrated;the male of O. nigroflagellaris Lin is reported for the first time. New distributional data are provided for O. japonica Yashiro, O. mediterranea Nowicki, O. pallida Kryger, O. polioptera Lin and O. shibuyae Ishii from China, and a key to all the Chinese species of the genus is given.     

Nutrient dynamics in a mangrove creek (North Brazil) during the dry season

During the dry season, dissolved inorganic nutrients and organic carbon (DOC) in a mangrove tidal creek (Bragança, North Brazil) presented a clear tidal signature: silicate, phosphate, ammonium and DOC covaried with salinity, with minima at high tide and maxima at low tide. Hydrodynamical calculations explained most diel variability as dilution of nutrientrich groundwater input by estuarine water. Creek nutrients tended to lower concentrations towards the end of the dry season, probably due to changes in groundwater dynamics. Ammonium was about 44% higher in the night than during the day, while silicate, phosphate nitrate + nitrite showed differences < 5%, indicating preferential autotrophic uptake of ammonium as nitrogen source. Nitrification and/or nitrogen fixation are probably sources of nitrate + nitrite, which contributed only 12% to the dissolved inorganic nitrogen pool. Dissolved oxygen (7%) and DOC (11%) were lower during the night, suggesting the existence of a labile, algalderived DOC pool. There is a loose coupling between aquatic primary production, groundwater dynamics and tidal regime.     

First report of Bursaphelenchus mucronatus kolymensis (Nematoda: Aphelenchoididae) on Monochamus sutor (Coleoptera: Cerambycidae) in Spain

This is the first report of Monochamus sutor as vector of B. mucronatus kolymensis, the European type of B. mucronatus (synonymous with B. kolymensis) in Spain. In 2013, a female of Monochamus sutor was caught in a Pinus sylvestris forest. Nematode species identification was based on morphological characteristics and on molecular and phylogenetic analysis of dauer juveniles and adults.     

红树林内生真菌1403的形态与分子鉴定(英文)

红树林内生真菌1403是从中国南海分离的一株镰刀菌,在液体发酵条件下能够产生灰黄霉素和葸醌类的抗生素。基于1403在形态学方面具有以下特征:产小型分生孢子的分生孢子梗较长,小型分生孢子呈椭圆形,大型分生孢子线形或略微弯曲,本文将它与有类似形态特征的镰刀菌进行了比较,发现1403与植物病原菌Fusarium verticillioides(有性态为Gibberella moniliforme)表面上很相似,气生菌丝均可产生大量假头状或链状的小型分生孢子,但深入的研究却发现1403与F.verticillioides具有不同的性状,如产生的多生分生孢子梗有时与单生分生孢子梗长度相当,产生环状菌丝,以及菌丝发生融合等现象,进一步以最大简约法和贝叶斯分析法将1403与其它相似镰刀菌进行系统发育比较,综合18S、28S、ITS三水平上的分析结果可以将1403归于镰刀菌亚组Gibberella fujikuroi,并最终在EF—1α水平上将其定为Fusarium proliferatum.