What does an African ethic of social cohesion entail for social distancing?

The most prominent strand of moral thought in the African philosophical tradition is relational and cohesive, roughly demanding that we enter into community with each other. Familiar is the view that being a real person means sharing a way of life with others, perhaps even in their fate. What does such a communal ethic prescribe for the coronavirus pandemic? Might it forbid one from social distancing, at least away from intimates? Or would it entail that social distancing is wrong to some degree, although morally permissible on balance? Or could it mean that social distancing is not wrong to any degree and could, under certain circumstances, be the right way to commune? In this article, I defend the latter view. I argue that, given an independently attractive understanding of how to value communal relationship, distancing oneself from others when necessary to protect them from serious incapacitation or harm can come at no cost to right action. However, I also discuss cases in which social distancing would evince a lack of good character, despite being the right thing to do.     

Transferring sediment containing intact seed banks: a method for studying plant community ecology

The experimental study of the ecology of natural plant communities is necessary to demonstrate the effects of environmental factors on plant growth. It allows one to make predictions of the likely effects of environmental changes on plant communities. Manipulating an entire ecosystem is complicated, and is rarely attempted. An alternative method is applied here for the submerged plant communities of the seasonally-flooded oligohaline marshes of the Camargue. It consists of collecting undisturbed sediment samples with their contained intact seed bank, and submitting them to different salinities. The study of total biomass and of the biomass of the more frequent species was carried out using parametric tests. The precision of the results depended on the frequency of the species in the replicates. When the frequency was low, non-parametric statistics were necessary. The method seems to be particularly suitable for the study of communities of annual species in aquatic environments.

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Résumé L'étude expérimentale de l'écologie des communautés naturelles de plantes est nécessaire pour démontrer les relations de cause à effet entre les facteurs environnementaux et l'abondance des plantes. Elle l'est également pour faire des prédictions réalistes sur les effets de modifications envisagées de l'environnement sur des communautés de plantes. La manipulation de l'écosystème complet est complexe, ce qui rend son utilisation rare. Une méthode alternative a été utilisée pour l'étude de la composition spécifique des communautés de plantes submergées des marais temporaires de Camargue. Elle consiste à prélever des échantillons non perturbés de sédiment, avec leur stock de semences intact, et à les soumettre à des conditions de salinité. L'étude de la biomasse totale et de la biomasse des espèces les plus fréquentes est faite au moyen de test paramétriques. La précision attendue des résultats dépend de la fréquence de l'espèce dans les réplicats. Lorsque la fréquence n'est pas élevée l'emploi de statistiques non paramétriques est indispensable. La méthode se révéle particulièrement bien adaptée à l'étude des communautés d'annuelles en milieu aquatique.

     

荒漠灌丛土壤动物分布及其生态功能

在干旱、半干旱荒漠生态系统中,灌丛作为一种重要的植被类型,其独特的形态和生理适应特性能够有效促进退化生态系统结构与功能的恢复。土壤动物是荒漠生态系统中不可或缺的重要组成部分,对促进灌丛"肥岛"演变具有重要的生态作用,有利于灌丛生态功能的发挥及退化生态系统的恢复。近年来,国内外学者对荒漠灌丛微生境土壤动物的研究逐步深入,取得大量的研究成果。在此基础上,首先综述荒漠灌丛微生境土壤动物群落分布和生态功能,总结灌丛与土壤动物分布间作用关系的数学模型,针对荒漠灌丛土壤动物研究中存在的问题提出了未来可能的研究方向和建议。     

Reciprocal Fitness Feedbacks Promote the Evolution of Mutualistic Cooperation

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微生物菌剂对楸树幼苗生长及根际土细菌群落结构的影响

为探究球毛壳ND35微生物菌剂对楸树幼苗生长及土壤肥力的作用机制，本研究楸树幼苗为研究对象，采用室内盆栽试验，设计0（CK），10（T1），15（T2），20（T3）4种微生物菌剂施用量，测定幼苗生长情况、土壤微生物组成结构、土壤酶和土壤养分等特征。研究结果如下：（1）球毛壳ND35微生物菌剂可显著促进楸树幼苗的生长，株高、地径、地上及地下生物量显著提高（P<0.05），T2处理下促生效果最好。（2）施用球毛壳ND35微生物菌剂可显著提高土壤中有机质、硝态氮、铵态氮含量及脲酶、磷酸酶、蔗糖酶活性（P<0.05）。（3）球毛壳ND35微生物菌剂可显著影响土壤细菌群落组成，提高细菌群落的丰富度和多样性，使土壤中β-变形菌纲（Betaproteobacteria）、γ-变形菌纲（Gammaproteobacteria）的相对丰度显著下降，α-变形菌纲（Alphaproteobacteria）、δ-变形菌纲（Deltaproteobacteria）的相对丰度呈显著提高，可使土壤中鞘氨醇单胞菌属（Sphingomonas）的相对丰度显著提高21.88%-103.56%（P<0.05），芽孢杆菌属（Bacillus）的相对丰度提高66.28%-65.97%（P<0.05），酸杆菌属（Acidibacter）的相对丰度提高12.76%-38.06%。（4）冗余分析（RDA）结果表明，土壤硝态氮、铵态氮、有机质是影响土壤细菌群落分布和多样性的重要环境因子，土壤细菌群落结构的改变会显著影响土壤脲酶、蔗糖酶、碱性磷酸酶的活性。因此，施用球毛壳ND35微生物菌剂可通过影响植物根际土壤的化学性质及生物性质，促进楸树幼苗的生长。这一研究结果为楸树繁育提供了新的指导方向，亦为将其用于困难立地及退化生态系统植被恢复提供基础理论指导。     

Long‐term change within a Neotropical forest: assessing differential functional and floristic responses to disturbance and drought

Disentangling the relative roles of biotic and abiotic forces influencing forest structure, function, and local community composition continues to be an important goal in ecology. Here, utilizing two forest surveys 20‐year apart from a Central American dry tropical forest, we assess the relative role of past disturbance and local climatic change in the form of increased drought in driving forest dynamics. We observe: (i) a net decrease in the number of trees; (ii) a decrease in total forest biomass by 7.7 Mg ha^?1 but when calculated on subquadrat basis the biomass per unit area did not change indicating scale sensitivity of forest biomass measures; (iii) that the decrease in the number of stems occurred mainly in the smallest sizes, and in more moist and evergreen habitats; (iv) that there has been an increase in the proportion of trees that are deciduous, compound leaved and are canopy species, and a concomitant reduction in trees that are evergreen, simple‐leaved, and understory species. These changes are opposite to predictions based on recovery from disturbance, and have resulted in (v) a uniform multivariate shift from a more mesic to a more xeric forest. Together, our results show that over relatively short time scales, community composition and the functional dominance may be more responsive to climate change than recovery to past disturbances. Our findings point to the importance of assessing proportional changes in forest composition and not just changes in absolute numbers. Our findings are also consistent with the hypothesis that tropical tree species exhibit differential sensitivity to changes in precipitation. Predicted future decreases in rainfall may result in quick differential shifts in forest function, physiognomy, and species composition. Quantifying proportional functional composition offers a basis for a predictive framework for how the structure, and diversity of tropical forests will respond to global change.     

Frequent,low‐amplitude disturbances drive high tree turnover rates on a remote,cyclone‐prone Polynesian island

Aim How important are frequent, low‐intensity disturbances to tree community dynamics of a cyclone‐prone forest? We tested the following hypotheses concerning the ‘inter‐cataclysm’ period on a remote Polynesian island: (1) tree turnover would be high and recruitment rates would be significantly higher than mortality; (2) low‐intensity disturbance would result in a marginal increase in tree mortality in the short term; (3) turnover would vary among species and would be associated with plant traits linked to differences in life history; and (4) mortality and recruitment events would be spatially non‐random. Location Tutuila, a volcanic island in the Samoan Archipelago, Polynesia. Methods We censused the tree (stem diameter ≥ 10 cm) community in 3.9 ha of tropical forest three times over a 10‐year period, 1998–2008. We calculated annual mortality, recruitment and turnover rates for 36 tree species. We tested for non‐random spatial patterns and predictors of mortality, and non‐random spatial patterns of tree recruitment. A 2004 cyclone passing within 400 km allowed us to measure the effects of a non‐cataclysmic disturbance on vital rates. Results Annual turnover was 2.8% and annual recruitment was 3.6%; these are some of the highest rates in the tropics, and likely to be a response to a cyclone that passed < 50 km from Tutuila in 1991. Species turnover rates over 10 years were negatively correlated with wood specific gravity, and positively correlated with annual stem diameter increment. Mortality was spatially aggregated, and a function of site, species and an individual’s growth rate. Recruitment was highest on ground with low slope. The low‐magnitude cyclone disturbance in 2004 defoliated 29% of all trees, but killed only 1.8% of trees immediately and increased annual mortality over 5 years by 0.7%. Main conclusions The inter‐cataclysm period on Tutuila is characterized by frequent, low‐amplitude disturbances that promote high rates of tree recruitment and create a dynamic, non‐equilibrium or disturbed island disequilibrium tree community. Species with low wood density and fast growth rates have enhanced opportunities for recruitment between cataclysms, but also higher probabilities of dying. Our results suggest that increases in the frequency of cyclone activity could shift relative abundances towards disturbance‐specialist species and new forest turnover rates.     

Using education as a public relations tool for biotechnology

The advances in the biotechnology industry, and in biosciences research are impressive by any measure, but it is not sufficient just to continue to make spectacular scientific breakthroughs. It is important that the general public is assisted to keep up with the pace of technological change. Some efforts have been made, but they have not been enough. A public relations strategy is required. The biotechnology industry needs to influence public opinion as well as lead discovery. The aims of a public relations campaign should not be just to inform and convince legislators and regulators, but should target the average consumer of the 21st century. There are two areas where the science community must direct its attention if the international public is to be brought along on this biotechnological odyssey: the compulsory school sector – including teachers, students and policy makers; and key sector groups that can be specifically targeted such as farmers, indigenous peoples, horticulturists, food sector people, health professionals, and in particular, the recently retired. If the potential of biotechnological advances is to be realised, scientists must be proactive in educating the general public. This will also involve educating the educators. No amount of public education will completely remove the opposition to genetic engineering, but with an educated public there is an increased opportunity for a fair debate and scare tactics, half-truths and innuendo will gain less traction.