Increasing litter species richness reduces variability in a terrestrial decomposer system

Debate on the relationship between diversity and stability has been driven by the recognition that species loss may influence ecosystem properties and processes. We conducted a litterbag experiment in the Scottish Highlands, United Kingdom, to examine the effects of altering plant litter diversity on decomposition, microbial biomass, and microfaunal abundance. The design of treatments was fully factorial and included five species from an upland plant community (silver birch, Betula pendula; Scots' pine, Pinus sylvestris; heather, Calluna vulgaris; bilberry, Vaccinium myrtillus; wavy-hair grass, Deschampsia flexuosa); species richness ranged from one to five species. We tested the effects of litter species richness and composition on variable means, whether increasing litter species richness reduced variability in the decomposer system, and whether any richness-variability relationships were maintained over time (196 vs. 564 days). While litter species composition effects controlled variable means, we revealed reductions in variability with increasing litter species richness, even after accounting for differences between litter types. These findings suggest that higher plant species richness per se may result in more stable ecosystem processes (e.g., decomposition) and decomposer communities. Negative richness-variation relationships generally relaxed over time, presumably because properties of litter mixtures became more homogeneous. However, given that plant litter inputs continue to enter the belowground system over time, we conclude that variation in ecosystem properties may be buffered by greater litter species richness.     

A compass for sustainable development

A response to the Nuffield Council on Bioethics Consultation from the Institute of Biology, the Association of Applied Biology, the British Crop Protection Council, the British Ecological Society, the British Electrophoresis Society, the British Grassland Society, and the Institute of Horticulture     

The costs,benefits, and limitations of organizational level stress interventions

Models of organizational stress posit that a number of undesirable employee states and behaviors, such as lower levels of well‐being and performance, and higher levels of absence and turnover are caused by organizational stress. It is often suggested that organizational level interventions which aim to reduce stress, such as job redesign, will therefore reduce or eliminate these states and behaviors. This suggestion is, however, based on two unsupportable assertions. The first is that these states and behaviors are caused by organizational stress. While there is some limited evidence for the role of stress, the quality of this evidence is severely compromised by numerous methodological and conceptual problems. The second assertion is that organizational level interventions aimed at changing some of these states and behaviors will actually have an effect, and that these effects will be uniformly positive. However, the available evidence suggests that these interventions often have little or no effect, and where they do have effects, these may be both positive and negative., The implications of this analysis for future work on organizational level stress interventions are discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

Estimating PAH sources in harbor sediments using diagnostic ratios

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the global environment and are subsequently transported into aquatic sediments. As PAHs are formed by various processes, source identification using diagnostic ratios can provide insight to PAH emission sources to distinguish between pyrogenic and petrogenic PAH sources. PAH diagnostic ratios were applied as a forensic source apportionment technique to assess aggregate historical sediment data from 31 small craft harbors (SCHs) across Nova Scotia, Canada. Multiple diagnostic ratios suggest that PAHs present in Nova Scotia SCH sediments are pyrogenic (combustion) in origin, while consistently suggesting that coal‐related PAH sources are potential dominant specific sources. National Institute of Standards and Technology Standard Reference Materials (SRMs) were used as reference for coal tar, urban dust, and diesel exhaust particulates in ratio applications. The SRM for coal tar was most similar to Nova Scotia SCH sediments in multiple ratio applications. Diagnostic ratio results were corroborated by comparing the PAH profile of sediments to source profiles from the literature. Results indicate that Nova Scotia SCH sediments follow global trends by exhibiting a dominant pyrogenic PAH signature, and the specific coal‐related PAH signature of Nova Scotia SCH sediments may be influenced by contamination inputs related to historical industrial coal mining and combustion activities in the province.     

Late Holocene wetland transgression and 500 years of vegetation and fire variability in the semi-arid Amboseli landscape,southern Kenya

The semi-arid Amboseli landscape, southern Kenya, is characterised by intermittent groundwater-fed wetlands that form sedimentary geoarchives recording past ecosystem changes. We present a 5000-year environmental history of a radiocarbon dated sediment core from Esambu Swamp adjacent to Amboseli National Park. Although radiocarbon dates suggest an unconformity or sedimentary gap that spans between 3800 and 500 cal year BP, the record provides a unique insight into the long-term ecosystem history and wetland processes, particularly the past 500 years. Climatic shifts, fire activity and recent anthropogenic activity drive changes in ecosystem composition. Prior to 3800 cal year BP the pollen data suggest semi-arid savanna ecosystem persisted near the wetland. The wetland transgressed at some time between 3800 and 500 cal year BP and it is difficult to constrain this timing further, and palustrine peaty sediments have accumulated since 400 cal year BP. Increased abundance of Afromontane forest taxa from adjacent highlands of Kilimanjaro and the Chyulu Hills and local arboreal taxa reflect changes in regional moisture budgets. Particularly transformative changes occurred in the last five centuries, associated with increased local biomass burning coeval with the arrival of Maa-speaking pastoralists and intensification of the ivory trade. Cereal crops occurred consistently from around 300 cal year BP, indicative of further anthropogenic activity. The study provides unique insight in Amboseli ecosystem history and the link between ecosystem drivers of change. Such long-term perspectives are crucial for future climate change and associated livelihood impacts, so that suitable responses to ensure sustainable management practices can be developed in an important conservation landscape.     

“Just” ecopreneurs: re-conceptualising green transitions and entrepreneurship

Economic, environmental, and social limits of the current capitalist mode of production have led to a rethinking and reconceptualisation of economic processes and models including the role of businesses in sustainable development. While green economies and more specifically green entrepreneurs have been identified as agents of change that can challenge the mainstream and seek to induce environmental, social, and ethical transformation of society, much research has stayed within existing models of thinking predominantly rooted in technocratic approaches (e.g. ecological modernisation and more recently transition studies). This paper seeks to offer an alternative understanding of green entrepreneurship that breaks open these discussions using an environmental justice frame that focuses on the role of extra-economic discourses in shaping the social relations of economic systems. By drawing on an exemplary case study of “just” entrepreneurship from Boston, Massachusetts, USA, the paper seeks to start a conversation around the ideas of green entrepreneurship and environmental justice as vehicles to deliver potentially broader system changes and explores both conceptual and practical aspects of green development. As such, it offers (1) evidence of a just green economy that can be realised within existing capitalist structures as well as (2) a different conceptual entry point to understanding green entrepreneurship.     

Levels and temporal trends (1983-2003) of persistent organic pollutants (POPs) and mercury (Hg) in seabird eggs from Northern Norway

The main objective of this study was to investigate possible temporal trends of persistent organic pollutants (POPs) and mercury in eggs of herring gulls (Larus argentatus), black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge) and Atlantic puffins (Fratercula arctica) in Northern Norway. Eggs were collected in 1983, 1993 and 2003. Egg concentrations of POPs (PCB congeners IUPAC numbers: CB-28, 74, 66, 101, 99, 110, 149, 118, 153, 105, 141, 138, 187, 128, 156, 157, 180, 170, 194, 206, HCB, alpha-HCH, beta-HCH, gamma-HCH, oxychlordane, trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT and p,p'-DDT) and mercury were quantified. Generally, POP levels decreased between 1983 and 2003 in all species. No significant temporal trend in mercury levels was found between 1983 and 2003.     

Physical and chemical characteristics of water from the hydrographic basin of the Poxim River, Sergipe State, Brazil

The Poxim River is one of Sergipe State’s major waterways. It supplies water to the State capital, Aracaju, but is threatened by urban and agricultural developments that compromise both the quantity and the quality of the water. This has direct impacts on the daily lives of the region’s population. In this work, a multivariate analytical approach was used to investigate the physical and chemical characteristics of the water in the river basin. Four sampling campaigns were undertaken, in November 2005, and in February, May, and September 2006, at 15 sites distributed along the Poxim. The parameters analyzed were conductivity, turbidity, color, total dissolved solids, dissolved oxygen, alkalinity, hardness, chlorophyll-a, and nutrients (total phosphorus, dissolved orthophosphate, nitrite, nitrate, ammoniacal nitrogen, and total nitrogen). Dissolved oxygen contents were very low in the Poxim-Açu River (1.0–2.8), the Poxim River (1.6–4.6), and the estuarine region (1.7–5.1), due to the dumping of wastes and discharges of domestic and industrial effluents containing organic matter into fluvial and estuarine regions of the Poxim. Factor analysis identified five components that were indicative of the quality of the water, and that explained 81.73 % of the total variance.     

Prioritizing debt conversion opportunities for marine conservation

Incentivized debt conversion is a financing mechanism that can assist countries with a heavy debt burden to bolster their long-term domestic investment in nature conservation. The Nature Conservancy, an international conservation-based nongovernmental organization, is adapting debt conversions to support marine conservation efforts by small island developing states and coastal countries. Prioritizing debt conversion opportunities according to their potential return on investment can increase the impact and effectiveness of this finance mechanism. We developed guidance on how to do so with a decision-support approach that relies on a novel threat-based adaptation of cost-effectiveness analysis. We constructed scenarios by varying parameters of the approach, including enabling conditions, expected benefits, and threat classifications. Incorporating both abatable and unabatable threats affected priorities across planning scenarios. Similarly, differences in scenario construction resulted in unique solution sets for top priorities. We show how environmental organizations, private entities, and investment banks can adopt structured prioritization frameworks for making decisions about conservation finance investments, such as debt conversions. Our guidance can accommodate a suite of social, ecological, and economic considerations, making the approach broadly applicable to other conservation finance mechanisms or investment strategies that seek to establish a transparent process for return-on-investment decision-making.