• Energy Research

Despite setbacks, interest in Jatropha cultivation remains high. This study addressed the question to what extent Jatropha cultivation has replaced specific vegetation and land use types and how the existing areas are managed. Major forms of land use change and management practices were identified based on cluster analysis of data from 106 interviewee's responses to a comprehensive global survey. Of the 1.04 × 10(6) ha cultivated with Jatropha in 2011 40% were established on land that was cleared of vegetation as a result of logging activities unrelated to Jatropha cultivation, 34% was defined as unused, and the remainder was attributable to areas previously used for crops or animal husbandry. With the exception of croplands, these areas were dominated (90-98%) by a few internationally active companies whose cultivation models were almost exclusively based on outgrower schemes. Management practices were largely extensive in nature (low mechanical input and infrequent use of fertilizers, pesticides and herbicides), and also dominated by large projects. Broad surveys, such as this, are useful in identifying general trends in this emerging global industry, but detailed case studies, particularly of large projects, are needed in order to draw more informed conclusions about the site-specific impacts of Jatropha cultivation.

PurposeThis article seeks to address aviation as an emerging biofuel consumer and to discuss sustainability issues and consequences for feedstock production concepts. Biojet fuels have been identified as a promising, readily deployable alternative to fossil‐based aviation fuels. At the same time they are highly criticised as their production may have negative social and environmental impacts. Therefore, the paper aims to identify major sustainability issues and assessment challenges and relate these to the production of biojet fuel feedstock.Design/methodology/approachTwo plant oil production concepts are presented that address the sustainability issues discussed. Both concepts are being investigated within the research project “Platform for Sustainable Aviation Fuels”. A literature‐based overview of sustainability issues and assessment challenges is provided. Additionally, conceptual insights into new plant oil production concepts are presented.FindingsThe use of biojet fuels is often hailed as a strategy for the aviation industry to become more sustainable. However, biofuels are not necessarily sustainable and their potential to reduce GHG emissions is highly debated. Several unresolved sustainability issues are identified highlighting the need for improved assessment methods. Moreover, the two concepts presented have the potential to provide sustainably grown feedstock, but further empirical research is needed.Originality/valueThis article addresses researchers and practitioners by providing an overview of sustainability issues and assessment challenges related to biojet fuels. Consequences are identified for two plant oil feedstock concepts: catch cropping in temperate regions and silvopastoral systems in tropical and subtropical regions.

The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of Arctic lemmings. However, few studies so far investigated habitat use during the Arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat features for their wintering sites. We examined yearly numbers and distribution of 22 769 winter nests of the collared lemming Dicrostonyx groenlandicus (Traill, 1823) from an ongoing long-term research on Traill Island, Northeast Greenland, collected between 1989 and 2019, and correlated this information with data on dominant vegetation types, elevation, and slope. We found that the number of lemming nests was highest in areas with a high proportion of Dryas heath, but was also correlated with other vegetation types, suggesting some flexibility in resource use of wintering lemmings. Furthermore, lemmings showed a higher use for sloped terrain, probably as it enhances the formation of deep snow drifts, which increases the insulative characteristics of the snowpack and protection from predators. With global warming, prime lemming winter habitats may become scarce through alteration of snow physical properties, potentially resulting in negative consequence for the whole community of terrestrial vertebrates.

AbstractPollination is critical to fruit production, but the interactions of pollination with plant resources on a plant's reproductive and vegetative features are largely overlooked. We examined the influences of pollination, irrigation and fertilisation on the performance of almond,Prunus dulcis, in northern California. We used a full‐factorial design to test for the effects of pollination limitation on fruit production and foliage variables of whole trees experiencing four resource treatments: (i) normal water and nutrients, (ii) reduced water, (iii) no nutrients, and (iv) reduced water and no nutrients. In each of these combinations, we applied three pollination treatments: hand‐cross pollination, open‐pollination and pollinator exclusion. Pollination strongly affected yield even under reduced water and no nutrient applications. Hand‐cross pollination resulted in over 50% fruit set with small kernels, while open‐pollinated flowers showed over 30% fruit set with moderate‐sized kernels. Pollinator‐excluded flowers had a maximum fruit set of 5%, with big and heavy kernels. Reduced water interacted with the open‐ and hand‐cross pollination treatments, reducing yield more than in the pollinator exclusion treatment. The number of kernels negatively influenced the number of leaves, and reduced water and no nutrient applications interacted with the pollination treatments. Overall, our results indicate that the influences of pollination on fruit tree yield interact with the plant availability of nutrients and water and that excess pollination can reduce fruit quality and the production of leaves for photosynthesis. Such information is critical to understand how pollination influences fruit tree performance.

Abstract Demand for bioenergy has rapidly developed in recent decades, resulting in expansion of bioenergy cropping systems such as willow short rotation coppice (SRC). Increasing the number of willow genotypes in SRC can potentially enhance species diversity in the associated arthropod community, which may promote ecosystem functions within plantations. However, the ecology of SRCs and their effects on biodiversity have only rarely been investigated. Therefore, to study the role of plant genetic diversity (GD) in SRC, we established a replicated common garden experiment comprising genetic monocultures and mixtures of two, three and four different Salix genotypes used in commercial SRC. We sampled arthropods and examined the effect of GD across trophic groups, to test if the use of genotype mixtures increases arthropod richness and abundance. Species richness of total arthropods and of herbivores increased significantly with increasing GD, regardless whether data were pooled per plot or analysed on tree level. However, effects varied among willow genotypes as positive correlations between GD and different trophic groups were genotype-specific. We show that establishing and managing commercial willow SRCs with a mixture of varying genotypes can help to increase arthropod diversity within a bioenergy system that is a promising renewable energy source.

During the last couple of years we (an economist and an ecologist) have been doing joint research on multiple ecosystem services across countries and continents. Realizing that environmental scientists of different disciplines sometimes use the same words—such as sustainability or efficiency—with distinct meanings, a crucial basis for our successful teamwork has been to define clear terminology and a mutual understanding of what we are talking about. Our impression was that many scientists, practitioners, and politicians feel the same, and would appreciate greater clarity concerning technical terms sometimes used in a colloquial way. This situation motivated us to write this essay. The Millennium Ecosystem Assessment has shown that it is an ambitious task to combine fragmented and disciplinary knowledge in a common inter- and transdisciplinary language. Our essay is meant to take up part of this challenge.

Plant oil is a key commodity in the global economy, particularly for food and bioenergy markets. However, current production practices often impair smallholder livelihoods, cause land use changes, and compete for food production. The neotropical palm Acrocomia aculeata is currently being promoted as a novel sustainable biomass feedstock, particularly for bioenergy, but only little is known about the palm's ecological requirements. Based on a comprehensive literature and database search for recorded occurrences of A. aculeata in Latin America, we computed an ecological niche modeling to determine the palm's potential distribution area based on climatic and soil variables. We subsequently considered current land cover and predicted future climate change scenarios to discuss the cultivation potential of A. aculeata within its possible distribution area. The results revealed a large potential to cultivate A. aculeata in Latin America under current abiotic environmental conditions. The two core distribution regions identified were (1) Central America including the Caribbean, northern Colombia and Venezuela, and (2) southern Brazil and eastern Paraguay. A considerable proportion of the medium to highly suitable growing areas were found to be currently used for agricultural production or covered by land types with high conservation and carbon sequestration value. Applying the model under the IPCC's A2A 'business as usual' emission scenario suggested that by 2080 the vast majority of suitable growing areas severely decline in extent or disappear entirely. Our ecological niche modeling thus shows that despite the palm's high cultivation potential, a sustainable deployment of A. aculeata requires a precautious, evidence-based approach.