Behaviour: an important diagnostic tool for Lake Malawi cichlids

Historically, the cichlid fishes of Lake Malawi, which probably represent one of the best examples of rapid radiation of vertebrates, have been diagnosed with morphological and genetic data. Many of the populations once thought to be conspecific have been hypothesized to be separate species based on behavioural data. The use of behavioural data, as expressed in mate choice based on colour patterns or bower shapes, has been successfully used to diagnose both rock‐dwelling and sand‐dwelling cichlid species. Additionally, a combination of bower shapes and courtship patterns have been used as synapomorphies to diagnose genera within the Lake Malawi cichlid flock. It is concluded that taxonomists need to include behavioural data with morphological and genetic databases to diagnose species and to determine the phylogenetic relationships within this diverse assemblage of fishes.     

An introduction to species concepts and speciation of fishes

More than 22 different species concepts have been proposed. The concepts in general reflect the philosophical outlook, particular expertise, and the groups on which the authors are working. The full‐length papers in this special issue dedicated to species concepts relative to fishes are based on presentations by the authors at the 2001 annual meeting of the American Society of Ichthyologists and Herpetologists at University Park, Pennsylvania, USA and generated much discussion on the topic of what constitutes a species.     

Diversity in mind: Towards a differentiated understanding of migrants’ recreational practices in urban forests

This paper presents results of a study investigating the relationship between migration and recreation in urban forests in two German cities. Research in this field is growing in Europe, yet in certain countries, such as Germany, it remains underdeveloped. Until now, it has revealed ambiguities and diverging results. Furthermore, it has been the subject of criticism and calls for more differentiation between and within migrant groups, as well as for more reflection on the categorisation of “migrant” or “ethnic group”. This paper builds on these claims and aims to shed new light on forest recreation and ethnicity through a context-sensitive research approach in the tradition of symbolic interactionism. It draws upon the analysis of 42 qualitative interviews conducted with people with a Turkish, Russian-German and no migration background. The analysis leads to the construction of five narratives, each of them regrouping respondents who share a similar perspective on a specific theme. The narratives show how personal life context and its interlinkages with migration influence the individual's perspectives on and uses of urban forest. They also show how lifestyle and gender shape recreational practices independently from migration background. Beyond the focus on individual experience, collective recreational practices attributed to some groups are expressed in the narratives. This paper addresses the social aspect of leisure and discusses how forest recreation affects the social construction of groups such as migrant groups.     

Emergy Evaluation of Lacandon Maya Indigenous Swidden Agroforestry in Chiapas, Mexico

The Lacandon Maya of Chiapas, Mexico practice a system of swidden agroforestry that mimics the surrounding ecosystem and its successional stages. Their fields rotate through grass (milpa), and shrub (acahual) and forest fallow stages that regenerate soil, nutrients, and seed banks. Each successional stage, including the fallow stages, produces over 25 types of crops, raw materials, and medicines. Lacandon traditionally do not use fertilizers, pesticides or herbicides. An emergy evaluation of Lacandon agroforestry was conducted to quantify resource use, productivity, environmental impact, and overall sustainability. Six systems were analyzed. The Emergy Yield Ratios of the systems ranged from 4.5 to 50.7, which indicated a high level of output per purchased investments. The agroforestry systems had minimal environmental impacts as shown by Environmental Loading Ratios between 0.03 and 0.38. The Emergy Sustainability Index (ESI) of the systems ranged from 12 to 1740, indicating a high level of sustainability. The high ESI values were partially due to a large fraction of renewable resources that varied from 0.72 to 0.97. ESI was dependent upon land area devoted to the system for each family, where greater land area resulted in higher values of ESI. Labor invested did not exhibit a direct effect on sustainability.     

Some impacts of restricting nuclear energy availability

Several manure handling methods, widely used in Hungary, were investigated to determine the extent of contamination of the environment with microorganisms. Without special handling equipment liquid manure massively contaminates the environment with microorganisms. Microbial contamination could not be prevented by filtration of the liquid manure through straw bales, but could be markedly reduced by homogenization. Combined chemical, physical and biological handling methods were highly effective in reducing contamination and were also characterized by low germ counts in the product. Testing of microbial survival times in sterile liquid manure showed that coliforms, staphylococci and echoviruses deteriorate rapidly, salmonellas, and aerobic sporeformers survive longer, and lactobacillus survival is intermediate between the two extremes.     

Consequences of nitrogen fertilization on soil methane consumption in a productive temperate deciduous forest

To investigate the consequences of long-term N additions on soil CH₄ dynamics, we measured in situ CH₄ uptake rates, soil profiles and kinetics parameters during the growing season in a temperate deciduous forest in northwestern Pennsylvania (Allegheny College Bousson Environmental Forest). Measurements were made in control and adjacent plots amended with 100 kg N ha^–1 year^–1 for 8 years. We found that the in situ consumption rates were 0.19±0.02 (mean±SE) for the control and 0.12±0.01 mg CH₄–C m^–2 h^–1 for the N treatment, indicating that consumption had been reduced by 35% after 8 years of N amendments. Despite the large difference in rates of consumption, there were no differences in the CH₄ concentration profiles between the control and N-amended plots. Laboratory incubations of CH₄ consumption throughout the soil column (organic horizon and mineral soil depths) showed that rates were greatest in the organic horizon of both control and N-amended soils, although consumption was reduced by 42% in the N-amended plot. However, the rate in the organic horizon was only about 50% the rate measured in organic horizons at other temperate forests. The apparent K_m [K_m(app)] value in the organic horizon of the control plot was fourfold less than the K_m(app) value in the organic horizon of another temperate forest, but similar to the K_m(app) values in adjacent plots amended with N for a decade. Unlike results for other temperate forests, K_m(app) values at Bousson generally did not decrease with soil depth. These results indicate that N cycling strongly controls the CH₄-consuming community, and suggest that alterations of the N cycle due to N deposition or addition may alter rates and the location of CH₄ consumption by soils, even in soils with high N content and cycling rates.