Woody species composition,diversity and structure of riparian forests of four watercourses types in Burkina Faso

Riparian forests are classified as endangered ecosystems in general,particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works.The modification of this important habitat is continuing,with little attention being paid to the ecological or human consequences of these changes.The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso.All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m.Density,dominance,frequency and species and family importance values were computed to characterize the species composition.Different diver-sity indices were calculated to examine the heterogeneity of riparian forests.A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests.The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests.Similarity in tree species composition between riparian forests was low,which indicates high beta diversity and reflects differences in habitat conditions and topography.The structural characteristics varied significantly along the phyto-geographical gradient and between the different types of riparian forests.The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals.Considering the ecological importance of riparian forest,there is a need to delineate and classify them along watercourses throughout the country.     

Relating genetic variation of ecologically important tree traits to associated organisms in full-sib aspen families

Knowledge on phenological, morphometric, and phytochemical variation of local progenies of European aspen (Populus tremula, L.) is limited. The goal of this study was to characterize variation in growth and ecologically important leaf properties in aspen full-sib families in relation to interacting organisms (mycorrhiza, endophytes, and insects) and to determine whether these interactions were affected by soil application of a systemic fungicide. In local progenies, within-family variation of neutral molecular genetic markers (nuclear microsatellites) was higher than between families. Significant variation in growth, production of phenolic defensive compounds and other phytochemical leaf traits was found between families. Phenolic compounds showed clear negative correlation with generalist herbivores, but did not result in negative trade-off with biomass production. Differences in mycorrhizal colonization were not found among full-sib families and application of a systemic fungicide suppressed neither mycorrhizal colonization nor infestation with insects. However, a strong suppression of endophytes occurred, whose long-term consequences may require attention when fungicides are used in agroforestry plantations.     

Effects of 17β-estradiol injection on the reproductive efficiency of freshwater crayfish,Astacus leptodactylus (Eschscholtz, 1823)

The effects of 17β-estradiol injection (10^?7mol/crayfish) in adult female Astacus leptodactylus on the reproductive efficiency (i.e., pleopodal egg and stage 1 juvenile numbers) were investigated. In addition, hepatosomatic index, gonodosomatic index, and 17β-estradiol (E2) levels of crayfish ovary, hepatopancreas, and heamolymph before and after injections were also determined. Results showed that E2 injection to females enhances the reproductive efficiency of A.leptodctylus. E2 injection significantly increased pleopodal egg and stage 1 juvenile numbers, GSI, HSI, and concentrations of E2 in heamolymph, ovary, and hepatopancreas. However, E2 injection did not accelerate time of mating and proportion of pleopodal egg-berried females at the first week of reproduction season in this species. This study highlights that to improve the reproductive efficiency of A.leptodctylus by using hormones to regulate the ovarian cycle, E2 should be used at least 1.5 months before the commencement of the breeding season.     

The chemical and sensorial changes in rainbow trout caviar salted in different ratios during storage

In this study, the intention was to investigate the chemical and sensorial changes occurring during cold storage (4 ± 1°C) of caviar obtained from rainbow trout Oncorhynchus mykiss W. 1792 that was dry salted in different ratios. Caviar has a higher fat and protein content than other seafood products, and in processing it with dry salting technology, it was determined that the shelf life could be up to 28 days for the experimental group in which salt was applied at a rate of 4% and up to 35 days for the experimental group in which salt was applied at a rate of 8%. Thus the storage period of the samples is longer for the products to which a high (8%) amount of salt was applied than the products to which a low (4%) amount of salt was applied in the salting process.     

Don't look back in anger! Responsiveness to missed chances in successful and nonsuccessful aging

Life-span theories explain successful aging with an adaptive management of emotional experiences like regret. As opportunities to undo regrettable situations decline with age, a reduced engagement into these situations represents a potentially protective strategy to maintain well-being in older age. Yet, little is known about the underlying neurobiological mechanisms supporting this claim. We used a multimodal psychophysiological approach in combination with a sequential risk-taking task that induces the feeling of regret and investigated young as well as emotionally successfully and unsuccessfully (i.e., late-life depressed) aged participants. Responsiveness to regret was specifically reduced in successful aging paralleled by autonomic and frontostriatal characteristics indicating adaptive shifts in emotion regulation. Our results suggest that disengagement from regret reflects a critical resilience factor for emotional health in older age.     

木材硅石改性剂的制备工艺

为了降低木材硅化改性成本促其应用,直接将固态硅石粉高效液态活化,通过正交试验和极差分析优化制备了木材硅石改性剂,测试分析了浸渍改性杨木的性能。结果表明:①反应时间和原料n(SiO2)∶n(NaOH)对活化溶液的pH值、黏度和密度影响不显著,碱料种类和反应温度对活化溶液的黏度、密度、SiO2转化率、固体质量分数和生产成本影响显著,对溶液性能综合影响最大的是反应温度和碱料种类,其次是n(SiO2)∶n(NaOH)和反应时间;②pH值随反应时间、温度和n(SiO2)∶n(NaOH)增大而减小,密度、黏度、固体质量分数、SiO2转化率和模数随反应时间、温度和n(SiO2)∶n(NaOH)增大而增大,KOH活化效果更好但价格较高,综合平衡优化工艺为:反应温度200℃、碱料为NaOH、n(SiO2)∶n(NaOH)=1.715∶1、反应时间4 h;③硅石改性剂能充分渗入杨木,使其吸药量达252%,密度提高81%,抗弯强度提高69.6%,炭化温度减小89℃,残炭率提高41%,改性效果优于硅溶胶。