Towards the reconstruction of the Holocene vegetation history of Lower Provence: two new pollen profiles from Marais des Baux

Two new¹⁴C-dated Holocene pollen profiles from Marais des Baux, Bouches-du-Rhône, France, are presented. The record begins in the Younger Dryas, when the vegetation consisted mainly of grasses and mugwort (Artemisia). The Preboreal was marked by a transitory expansion of pine forests and was followed by the establishment of a rich deciduous oak-forest that included hazel (Corylus) and elm (Ulmus). During the Boreal, hazel played a dominant role within the oak-forest. The oak forests, which includedQuercus ilex, achieved a major expansion during the Atlantic period. The Subboreal was characterised by the regional establishment of, firstly, fir (Abies) and then beech (Fagus). The spread and expansion of beech coincides with the first clear evidence for farming. Agricultural activities brought about the decline of deciduous oak-forest. During the Subatlantic, forests in the vicinity of Marais des Baux were cleared for farming. Cereal growing, which included rye cultivation, was of considerable importance. Three noteworthy characteristics that serve to differentiate the Holocene vegetation history of the low-lying Provence region from other French regions are as follows: 1) the early establishment (from the onset of Preboreal) of low altitude mixed forest; 2) the expansion during the Subboreal of fir and beech in low altitude areas with a Mediterranean climate and, 3) the exceptional taxonomic richness of the pollen assemblages (120 identified taxa) and the presence of borealalpine and Euro-Siberian taxa that no longer exist in Lower Provence.     

Systematic review of the land snails of the Pitcairn Islands

The land snails (and semi-terrestrial molluscs) of the four islands that comprise the Pitcairn group are reviewed and the indigenous species illustrated. The strictly terrestrial molluscan faunas from the two atolls (Oeno and Ducie) are poor, like many other atolls in the Pacific. Each supports less than six species with wide geographical ranges. In contrast, the terrestrial molluscan fauna from Henderson Island, an uplifted atoll, is more diverse with at least 16 species belonging to seven families. Over half these taxa appear to be endemic, at least at the level of sub-species. Two species of semi-terrestrial molluscs have also been found on Henderson. Analyses of archaeological deposits in caves near the North Beach have revealed that at least a further six species of land snail formerly occurred on Henderson. The volcanic island of Pitcairn, the only island in the group still inhabited, supports the greatest number of terrestrial molluscs. Twenty-six species of land snail (and one semi-terrestrial pulmonate) were found living there during the recent expedition and a further three taxa were recognized amongst museum material. At least seven of these species are thought to be recent adventives and a further three are likely to have been prehistoric introductions. One Henderson (Georissa hendersoni) and three Pitcairn endemics (Pacificella filica, Sinployea pitcaimensis and Diastole tenuistriata) are formally described as new species. Some of the Pitcairn endemics occur in very restricted areas (less than a hectare) and it is important that measures should be taken to prevent the spread of invasive plants, such as rose-apple, that would threaten their survival.     

Role of ethylene in auxin-induced flower bud formation in tobacco explants

The effect of ethytene on in vitro flower bud formation in thin-layer explants from tobacco pendicels ( Nicotiana tabacum L. cv. Samsun) was studied Endogenous ethylene production was stimulated by l-minocyclopropanc-l-carhoxylic acid (ACT), and inhibited by aminoethoxyviny lglycine (AVG). resulting in higher and lower ethylene accumulation. respectively. In the presence of an elevated ethylene concentration, the number of flower buds formed after 7 days of culture in explants was increased, compared with the control. Treatment with AVG or with AgNO₃ which blocks ethylene action resulted in decreased bud numbers after 7 days of culture. A different effect of ethylene was visible after 14 days of culture, when regeneration was complete. Treatment with AgNO₃ led to more bud regeneration, and increasing ethylene concentrations to lower bud numbers. The endogenous production of ethylene was enhanced by high concentrations of 1-naphthaleneacetic acid (NAA).
The inhibitory effect of applied ethylene was almost 100% in explants cultured at low concentrations of NAA (below 1 μ M ). but hardly visible at high concentrations (4.5 μ M ). As a consequence, the optimal NAA concentration shifted to a higher value in the presence of ethylene. These results are interpreted as a reduction in tissue sensitivity to auxin and in regenerative capability by ethylene. The effect of ethylene on auxin action is not exerted at the level of hormone concentration. Neither NAA uptake nor conversion to conjugates was effected by ethylene.     

Performance of Piezodorus guildinii on four species of Indigofera legumes

Piezodorus guildinii (Westwood) (Heteroptera: Pentatomidae), a major pest of soybean in South America, feeds on alternative legume hosts, and four species of Indigofera were tested. Nymphal survival was 88% on I. endecaphylla Jacq. (IE), 15% on I. suffruticosa Mill. (IS), 70% on I. hirsuta L. (IH) and 40% on I. truxilliensis H.B.K. (IT). From stadia 2 through 5, fastest development (22 days) occurred on IE and IT, and the slowest (29 days) on IS. Fresh body weight at emergence was higher for nymphs fed on IE and IT. Adult survival of P. guildinii after 40 days, was greater than 70% on IT and IE, and less than 20% on IS. Females oviposited on all Indigofera species, but <30% were observed to lay eggs on IS. Body weight gain during the first week was greater for adults feeding on IE and IH. Insects lost weight on IS; at the end of day 15 no differences in percent change in body weight, among the food plants tested, were observed. Field surveys conducted on IT and IS, the two most abundant species in northern Paraná, indicated a greater number of nymphs, adults, and egg masses on the former host. On both hosts P. guildinii was more abundant during April/May, after soybean harvest, suggesting movement of the populations from soybean to Indigofera.     

Identification and characterization of Neopestalotiopsis clavispora associated with leaf blight of small cardamom (Elettaria cardamomum Maton)

Leaf blight is a major foliar disease prevalent in all cardamom‐cultivating tracts, manifesting in diverse forms of symptoms. In this study, six symptomatological variants were delineated based on the expression of foliar symptoms in cardamom genotypes (Malabar, Mysore and Vazhukka) and designated as SV 1 to SV 6. Among the symptomatological variants, SV 1, SV 2, SV 3 and SV 6 were more pronounced in Vazhukka, while SV 4 and SV 5 were prominent in Malabar type. Subsequent isolation from the variants yielded whitish colonies, which were correspondingly coded as SV 1 to SV 6. The conidia were fusiform, five‐celled, with three median versicoloured cells, two terminal hyaline cells and measured 23.1–27.25 × 3.84–4.43 μm. The apical cells had two to three tubular, flexuous, unbranched appendages, whereas the basal appendage was single, tubular and unbranched. Based on conidial characteristics and molecular characterization with internal transcribed spacer rDNA region, partial β‐tubulin, translation elongation factor 1 alpha and large subunit (28S) of the nrRNA genes revealed identity of the pathogens as Neopestalotiopsis clavispora. The pathogenicity test was performed on Malabar, Mysore and Vazhukka genotypes, and Koch’s postulates were proved. In‐vitro interaction at three temperature regimes indicated that N. clavispora was inhibitory to Colletotrichum gloeosporioides at 10 and 30°C. Among the fungicides, carbendazim, propiconazole and carbendazim‐mancozeb completely arrested hyphal growth of N. clavispora under in‐vitro conditions. This study constitutes first report on the association of Neopestalotiopsis clavispora with leaf blight disease of small cardamom.     

Environmental impact assessment: the growing importance of science in government decision making

The broad acceptance of the conclusions and recommendations contained in the Brundtland Report with its emphasis on environmentally sustainable development is a good indication that this concept is gaining world-wide recognition. Science and the ensuing technology must be credited for creating and sustaining our modern society and we must now apply our expertise to minimize the adverse impacts of industrial growth and preserve our environment.Real progress towards the reconciliation of economic and environmental goals will require effective incorporation of environmental impact assessment (EIA) into the planning process and this paper describes the steps taken to improve the concept and practice of EIA in Canada. Public trust and participation in the process are key ingredients for its success as well as good science and meaningful dialogue between the scientists, the public and the decision makers. The availability of standard and reliable bioassessment techniques, which is the theme of this conference, should be helpful in strengthening the scientific basis for biophysical aspects of EIA.     

Assessment of the impact of the Lower Kihansi Hydropower Project on the forests of Kihansi Gorge, Tanzania

Construction of a hydropower project on the Kihansi river in Southern Tanzania will substantially alter the river's flow. On the basis of both qualitative and quantitative botanical surveys, forest in the Kihansi gorge below the dam site was found to be mostly typical species and endemic-rich Eastern Arc forest. An unusual forest type, dominated almost entirely by Filicium decipiens was also present. Eastern Arc forests are of both global and national importance for biodiversity conservation, and measures to mitigate impact of the dam on the forest are suggested. Further environmental monitoring is recommended in order to evaluate the choice of mitigation measures.     

Regeneration of an electropolymerised polypyrrole layer for the amperometric detection of ammonia

During recent years, attempts have been undertaken to utilise electrochemically polymerised pyrrole for amperometric detection of ammonia. However, these attempts suffer from gradual decrease of sensitivity of the polypyrrole layer with increasing ammonia exposure, and trials to regenerate the polypyrrole failed until now. In this communication, we present recovery of polypyrrole sensitivity by treatment with perchloric acid and subsequent oxidation. Consequently, a higher durability of polypyrrole-based ammonia sensors could be achieved.