Tree Diversity, Initial Litter Quality, and Site Conditions Drive Early-Stage Fine-Root Decomposition in European Forests

Decomposition of dead fine roots contributes significantly to nutrient cycling and soil organic matter stabilization. Most knowledge of tree fine-root decomposition stems from studies in monospecific stands or single-species litter, although most forests are mixed. Therefore, we assessed how tree species mixing affects fine-root litter mass loss and which role initial litter quality and environmental factors play. For this purpose, we determined fine-root decomposition of 13 common tree species in four European forest types ranging from boreal to Mediterranean climates. Litter incubations in 315 tree neighborhoods allowed for separating the effects of litter species from environmental influences and litter mixing (direct) from tree diversity (indirect). On average, mass loss of mixed-species litter was higher than those of single-species litter in monospecific neighborhoods. This was mainly attributable to indirect diversity effects, that is, alterations in microenvironmental conditions as a result of tree species mixing, rather than direct diversity effects, that is, litter mixing itself. Tree species mixing effects were relatively weak, and initial litter quality and environmental conditions were more important predictors of fine-root litter mass loss than tree diversity. We showed that tree species mixing can alter fine-root litter mass loss across large environmental gradients, but these effects are context-dependent and of moderate importance compared to environmental influences. Interactions between species identity and site conditions need to be considered to explain diversity effects on fine-root decomposition.

Plant morphometry matches beetle diversity: effects of natural adjacent vegetation on grain Amaranth crop under small-holder conditions

Grain Amaranth, Amaranthus hypochondriacus L., is an emerging arable crop cultivated worldwide. One way to obtain resources from the crop, other than grain, is to grow Amaranths in the dry season and harvest only the leaves. In this environmental condition the response of an Amaranth agroecosystem to the presence of natural and semi-natural habitats or other crops has not been studied yet. We analysed the response of (1) Amaranth morphometry and (2) alpha and beta diversity of beetles to the nearness of adjacent vegetation and natural habitats (such as deciduous forest) at the small-holder conditions. Our results showed that A. hypochondriacus crop plants responded positively to the presence of an ecotone (adjacent vegetation) and the natural habitat (deciduous forest), i.e., A. hypochondriacus plants grew bigger in the section nearest to adjacent vegetation, which was a pattern consistent in time. Moreover, for beetles (considered as a bioindicator group), richness was different amongst the study areas and negatively followed the gradient of perturbation. These results suggest that Amaranth crop is sensitive to the presence of natural and semi-natural habitats but not to other crops in the dry season. In addition, beetles match the response of Amaranth plants. This is the first time that this type of data is recorded in grain Amaranth agroecosystem and it will help to understand the interaction amongst grain Amaranth agroecosystems, biodiversity, and natural adjacent vegetation to boost ecosystem services.

A Study Space Analysis of Interpretation Service Needs and Optimisation

The paper reports a study space analysis (SSA) of 117 published investigations of the need for interpretation services and approaches to their optimisation. The study explores literature on the adequacy and ecological validity of interpretation service and interpretation optimisation. Research on rapport building appears to be the most investigated issue. Studies on interpretation services need and planning are infrequently researched, and there exist little or no study investigating police diversity effects on interpretation service needs and the planning effects. Studies investigating cognitive load, language, and gender effects on interpreting accuracy are sparse, with most research effort concentrated in conference interpreting settings.

The hump-shaped effect of plant functional diversity on the biological control of a multi-species pest community

Plant taxonomic and functional diversity promotes interactions at higher trophic levels, but the contribution of functional diversity effects to multitrophic interactions and ecosystem functioning remains unclear. We investigated this relationship in a factorial field experiment comparing the effect of contrasting plant communities on parasitism rates in five herbivore species. We used a mechanistic trait-matching approach between plant and parasitoids to determine the amount of nectar available and accessible to parasitoids. This trait-matching approach best explained the rates of parasitism of each herbivorous species, confirming the predominant role of mass-ratio effects. We found evidence for an effect of functional diversity only in analyses considering the ability of plant communities to support the parasitism of all herbivores simultaneously. Multi-species parasitism was maximal at intermediate levels of functional diversity. Plant specific richness had a negligible influence relative to functional metrics. Plant communities providing large amounts of accessible nectar and with intermediate levels of functional diversity were found to be the most likely to enhance the conservation biological control of diverse crop herbivores.

Crop diversity effects on temporal agricultural production stability across European regions

Stabilizing agricultural production is fundamental to food security. At the national level, increasing the effective diversity of cultivated crops has been found to increase temporal production stability, i.e., the year-to-year stability of total caloric production of all crops combined. Here, we specifically investigated these effects at the regional level for the European Union and tested the effect of crop diversity in relation to agricultural inputs, soil properties, climate instability, and time on caloric, protein, and fat stability, as we hypothesized that the effect of diversity is context dependent. We further investigated these relationships for specific countries. We found that greater crop diversity was consistently associated with an increase in production stability, particularly in regions with large areas equipped for irrigation and low soil type diversity. For instance, in Spain and Italy, crop diversity showed the strongest positive effect among all predictors, while on the European level, the stabilizing effect of nitrogen use was substantially higher. In Germany, the crop diversity-stability relationship was weak, suggesting that crops react similarly to climatic, economic, and political factors or are grown in the same periods. With this study, we substantiate previous findings that crop diversity stabilizes agricultural caloric production and extend these with regard to protein and fat. The results elucidate the key drivers that enhance production stability for different European countries and regions, which is of key importance for a comparably productive agricultural region like Europe.