Civic modes of greening the city? Urban natures in-between familiar engagement and green critique

ABSTRACT

In this article, we deploy the loosely bounded phenomenon of “urban green communities” – in the shape of urban gardening, beekeeping, food collectives, biodiversity enhancement, tree planting and kindred citizen-based group practices towards urban greening – in order to probe the wide variations in modes of civic engagement with urban sustainability politics. As such, we explore the conceptual gaps opened up in-between everyday lifestyle politics, green social movements and critiques of neoliberal urban political economies, by leveraging a novel and fine-grained conceptualization of civic and place-based material participation built from pragmatic sociology. The work of Laurent Thévenot on regimes of engagement, in particular, allow us to trace translations in-between the familiar attachments and the public critiques undertaken by urban green communities in ways that expand the frame on socio-material politics relative to current research conversations. Empirically, we leverage this re-conceptualization as part of a comprehensive digital mapping exercise set in Denmark, in which we trace core patterns and differences in modes of urban-green politics at the level of everyday citizen practices and group interaction styles across a diversity of urban green communities. Having identified six such civic modes of urban greening and specified their group styles of engagement, we end by discussing the implications of our findings for questions of care, justice and democracy in sustainable city-making.     

Heavy metal load and dominance hierarchy in juvenile willow tits during winter

Possible links between plasma testosterone levels, heavy metal loads and dominance in juvenile male willow tits (Parus montanus) are studied during winter conditions in Norway. Dominant individuals have better access to food resources, significantly higher cadmium content in the liver and higher plasma testosterone level compared to subordinates. A positive correlation was also found between plasma testosterone level and content of cadmium in the liver. Although the results in our study shows only a limited difference in testosterone level of dominant and subordinate juvenile male willow tits, possible small changes in behaviour might have crucial effects on winter survival of these birds.     

Estimation methods for nonlinear state-space models in ecology

The use of nonlinear state-space models for analyzing ecological systems is increasing. A wide range of estimation methods for such models are available to ecologists, however it is not always clear, which is the appropriate method to choose. To this end, three approaches to estimation in the theta logistic model for population dynamics were benchmarked by Wang (2007). Similarly, we examine and compare the estimation performance of three alternative methods using simulated data. The first approach is to partition the state-space into a finite number of states and formulate the problem as a hidden Markov model (HMM). The second method uses the mixed effects modeling and fast numerical integration framework of the AD Model Builder (ADMB) open-source software. The third alternative is to use the popular Bayesian framework of BUGS. The study showed that state and parameter estimation performance for all three methods was largely identical, however with BUGS providing overall wider credible intervals for parameters than HMM and ADMB confidence intervals.     

Metals and organotins in multiple bivalve species in a one-off global survey

The Galathea 3 expedition circumnavigated the globe in 2006-2007 and collected marine samples from six continents. Bivalves were collected from harbours, other impacted locations and reference sites, and samples from 57 sites were analyzed for metals and 47 for organotins, to assess current contamination levels on a global scale. Metal concentrations in nine bivalve species were normalised to the Mytilidae family using conversion factors based on cosampled species and literature bioconcentration factors. The lowest metal and tributyltin concentrations were below background assessment concentrations (BACs) agreed in the Oslo-Paris convention (OSPAR) for the North Sea, and at most harbours the concentrations were orders of magnitude above BACs. The lowest concentrations of Cd and Pb measured here suggest that the BACs should be lower in a worldwide context. The sources of metals were classified according to human impact using principal component analysis. High relative concentrations of Hg, Pb and P were source indicators for industrial activity and land use; Zn, organotins, Cd and Cu for shipping activities, and V for oil spills. Generally the concentration levels at reference sites were low, but not always lower than expected impacted areas. The most contaminated areas were harbours, where especially Copenhagen, St Croix and Sydney, can be considered hotspots of tributyltin as well as a number of metals.     

Counteracting the focusing illusion: Effects of defocusing on car users’ predicted satisfaction with public transport

Car users underestimate their potential satisfaction with public transport due to a focusing illusion (i.e., focusing on a too narrow range of aspects related to the focal event). To investigate whether a defocusing technique would increase car users’ predicted satisfaction with public transport, the effects of defocusing techniques, generic (Study 1) and self-relevant (Study 2), were investigated. In Study 1 (estimate daily time spent on ten pre-selected activities), the generic defocusing technique did not generate higher predicted satisfaction with public transport. In Study 2, the self-relevant defocusing technique generated higher predicted satisfaction on quality attributes, namely satisfaction with the number of departures, the number of available seats and the condition of the vehicles, in comparison with controls. It is concluded that the self-relevant defocusing technique applied in Study 2 (state your various everyday activities and describe how much time you engage in them) was successful in making car users take into account activities in life that will remain unchanged if they were to use public transport for their daily travel. Additionally, in Studies 1 and 2, it was found that car-use habit, regardless of the experimental condition, influenced the magnitude of predicted satisfaction, that is, the higher the car-use habit, the lower the predicted satisfaction with public transport.     

Essential fatty acids influence metabolic rate and tolerance of hypoxia in Dover sole (Solea solea) larvae and juveniles

Dover sole (Solea solea, Linneaus 1758) were raised from first feeding on brine shrimp (Artemia sp.) with different contents and compositions of the essential fatty acids (EFA) arachidonic acid (ARA, 20:4n − 6); eicosapentaenoic acid (EPA, 20:5n − 3), and docosahexaenoic acid (DHA, 22:6n − 3), and their metabolic rate and tolerance to hypoxia measured prior to and following metamorphosis and settlement. Four dietary Artemia preparations were compared: (1) un-enriched; (2) enriched with a commercial EFA mixture (Easy DHA SELCO Emulsion); (3) enriched with a marine fish oil combination (VEVODAR and Incromega DHA) to provide a high ratio of ARA to DHA, and (4) enriched with these fish oils to provide a low ratio of ARA to DHA. Sole fed un-enriched Artemia were significantly less tolerant to hypoxia than the other dietary groups. Larvae from this group had significantly higher routine metabolic rate (RMR) in normoxia, and significantly higher O₂ partial pressure (PO₂) thresholds in progressive hypoxia for their regulation of RMR (P _crit) and for the onset of agitation, respiratory distress and loss of equilibrium. Metamorphosis was associated with an overall decline in RMR and increase in P _crit, but juveniles fed on un-enriched Artemia still exhibited higher P _crit and agitation thresholds than the other groups. Sole fed un-enriched Artemia had significantly lower contents of EFA in their tissues, both before and after settlement. Thus, enriching live feeds with EFA has significant effects on the respiratory physiology of sole early life stages and improves their in vivo tolerance to hypoxia. We found no evidence, however, for any effect of the ratio of ARA to DHA.     

Container-grown tree seedling responses to sodium chloride applications in different substrates

Seedlings of Norway maple (Acer platanoides), silver birch (Betula pendula), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) were grown in selected sodium chloride (NaCl) concentrations, soil types and under different watering regimes. Plants were raised from seeds, except for Scots pine plants which were obtained from a commercial source. Among the plant species tested, Scots pine was the most tolerant to soil salinity, while Norway spruce was the most susceptible. For both Norway maple and Norway spruce some half-sib families were more tolerant than others. No significant correlation was found between the tolerance of different half-sib families and the tolerance of mother trees observed in the field. The extent of leaf necrosis correlated significantly with the leaf concentrations of sodium (Na) and chloride (Cl). Among half-sib families within the species no such correlation was found. On the other hand, the least injured progeny of Norway maples had the highest concentrations of NaCl. The extent of salt-induced leaf necrosis varied with soil type, and a significant interaction between species and soil type was observed. Seedlings of Norway spruce grown in sand showed more severe necrosis and significantly higher concentrations of Na and Cl than seedlings grown in loam, silt loam, and peat. The severity of salt-induced leaf injury varied with the watering regime. Silver birch was the most affected species by drought and autumn watering treatments. Plants of silver birch subjected to drought showed increased leaf necrosis compared to the non-treated plants, and autumn watering treatment reduced the severity of leaf necrosis.     

Induction of trypsinogen secretion in herring larvae (Clupea harengus)

Mechanisms initiating trypsinogen secretion were studied in laboratory reared herring larvae (Clupea harengus L.) exposed to physical and chemical stimuli. Pancreatic secretion of trypsinogen was quantified for each stimulus type as the increase above pre-stimulus level of intestinal trypsin content. Larval prey types were: nauplii, copepodites or adult Acartia tonsa, small polystyrene spheres (diameter 94 m), small (diameter 79 m) or large (diameter 170 m) polystyrene-latex spheres. Intestinal trypsin content can be expressed as a function of two variables: meal size and content of pancreatic trypsinogen. Trypsinogen secretion increases with different prey items in the order: small spheres, nauplii and copepodites. Larvae which eat large spheres secrete more enzyme than if fed small spheres but trypsinogen secretion is similar in fish larvae fed copepodites and large spheres. The fact that the size of non-biodegradable particles exerts a major control over trypsinogen secretion suggests neural — as opposed to chemically mediated — initiation of secretion. A cephalic phase of secretory stimulation could not be demonstrated during swallowing of copepods or exposure for 2 to 3 h to compounds which leak from live copepodites. As cephalic and gastric phases of secretory stimulation are absent, initiation of trypsinogen secretion must take place in the intestine. Larval herring retain trypsin in the intestine. Ca. 4.5 h after a meal, 3/4 of the enzyme is located in the intestinal fluid, presumably available for hydrolysis of subsequent meals, and the high proportion (ca. 25%) of the pancreatic trypsinogen content which is secreted for copepodite prey may thus not be energetically wasteful for the larvae.     

The significance of hotspots to lekking topi antelopes (<Emphasis Type="Italic">Damaliscus lunatus</Emphasis>)

Controversy has surrounded the question of why lek-breeding has evolved in certain ungulate species. Can the behavior be explained simply by males mapping onto a female distribution that is determined by factors unrelated to mating? Or are leks created because estrous females distinguish between males and favor males who cluster? Here I address these questions by looking at spatial distribution in lekking topi antelopes (Damaliscus lunatus). Contrary to the predictions of a model assuming male clustering in the zone of maximum female range overlap, territories were highly clustered also within this zone, and lek size correlated positively with population density. In support of models derived from the ideal free distribution of males onto female dispersion, leks were in areas with high female density during the rut. However, models not taking into account both individual variation in male quality and female mate preferences failed to explain the extreme male clumping also within high density areas, which was revealed by a strongly male-biased sex-ratio on leks. Additional support for the female preference-based model came from the finding that estrous females concentrated onto leks. Female preference for clustered males may develop if males initially follow an ideal free distribution of unequal competitors with high quality males slightly clustered at density hotspots; positive feedback between female benefits of preference for clustered males and male benefits of clustering could lead to contraction of the territorial network and lek behavior. Thus only the female preference-based model correctly predicted a negative correlation between male mating rate and resource density.     

Echolocation in two very small bats from Thailand Craseonycteris thonglongyai and Myotis siligorensis

Summary The echolocation and hunting behavior of two very small bats, Craseonycteris thonglongyai (Hill) and Myotis siligorensis (Horsfield), from Thailand, were investigated using multiflash photographs, video, and high-speed tape recordings with a microphone array that allowed determination of distance and direction to the bats. C. thonglongyai is the world's smallest mammal and M. siligorensis is only slightly larger. Both bats hunted insects in open areas. The search signals of C. thonglongyai were 3.5 ms long multiharmonic constant frequency (CF) signals with a prominent second harmonic at 73 kHz repeated at around 22 Hz. The band width (BW) of the short terminal frequency modulated (FM) sweep increased during the very short approach phase. In the final buzz the CF component disappeared, the duration decreased to 0.2 ms, and the repetition rate increased to 215 Hz (Figs. 2, 3, 4). There was no drop in frequency in the buzz. The video recordings of C. thonglongyai indicated that it seizes insects directly with the mouth (Fig. 1). M. siligorensis produced 5.4 ms long CF search signals at 66 kHz. The repetition rate was around 13 Hz. In the approach phase an initial broad band FM sweep was added. The buzz consisted of two phases, buzz I and buzz II. Buzz 11 was characterized by short cry durations (around 0.3 ms), a constant high repetition rate (185 Hz), a distinct drop in frequency, and a prominent second harmonic (Figs. 5, 6, 7). The drop in frequency, apparently typical of vespertilionid bats, has been explained by physiological limitations in sound production. However, C. thonglongyai produced very short signals at very high repetition rates without any frequency drop. The drop may be of adaptive value since it enables M. siligorensis to produce very short signals with high sweep rates. The drop moves the pronounced second harmonic into the frequency range of most interest to the bat (Fig. 7D). The sweep rate in this frequency range may now increase to twice the maximum rate that the vocal cords can produce directly. C. thonglongyai and M. siligorensis belong to different superfamilies, Emballonuroidea and Vespertilionoidea, respectively. In spite of their phylogenetic distance they produce strikingly similar search signals of narrow BW around 70 kHz with high source levels (100–115 dB peSPL peak equivalent sound pressure level). We argue that the signal resemblance is due to the similarity in size and hunting behavior of the two bats both hunting insects in open areas. High frequencies are heavily attenuated in air, but because of their small size the bats are restricted to hunting small insects which only reflect echoes at high frequencies. Thus, the emitted frequency is probably the lowest possible given the prey size. Hence, the two bats can only maximize the range of their sonar by decreasing the BW and emitting high intensities. Correspondence to: A. Surlykke