Abstract. Country-specific soil organic carbon (SOC) estimates are the baseline for the Global SOC Map of the Global Soil Partnership (GSOCmap-GSP). This endeavor is key to explaining the uncertainty of global SOC estimates but requires harmonizing heterogeneous datasets and building country-specific capacities for digital soil mapping (DSM). We identified country-specific predictors for SOC and tested the performance of five predictive algorithms for mapping SOC across Latin America. The algorithms included support vector machines (SVMs), random forest (RF), kernel-weighted nearest neighbors (KK), partial least squares regression (PL), and regression kriging based on stepwise multiple linear models (RK). Country-specific training data and SOC predictors (5 × 5 km pixel resolution) were obtained from ISRIC -World Soil Information. Temperature, soil type, vegetation indices, and topographic constraints were the best predictors for SOC, but country-specific predictors and their respective weights varied across Latin America. We compared a large diversity of country-specific datasets and models, and were able to explain SOC variability in a range between ∼ 1 and ∼ 60 %, with no universal predictive algorithm among countries. A regional (n = 11 268 SOC estimates) ensemble of these five algorithms was able to explain ∼ 39 % of SOC variability from repeated 5-fold cross-validation. We report a combined SOC stock of 77.8 ± 43.6 Pg (uncertainty represented by the full conditional response of independent model residuals) across Latin America. SOC stocks were higher in tropical forests (30 ± 16.5 Pg) and croplands (13 ± 8.1 Pg). Country-specific and regional ensembles revealed spatial discrepancies across geopolitical borders, higher elevations, and coastal plains, but provided similar regional stocks (77.8 ± 42.2 and 76.8 ± 45.1 Pg, respectively). These results are conservative compared to global estimates (e.g., SoilGrids250m 185.8 Pg, the Harmonized World Soil Database 138.4 Pg, or the GSOCmap-GSP 99.7 Pg). Countries with large area (i.e., Brazil, Bolivia, Mexico, Peru) and large spatial SOC heterogeneity had lower SOC stocks per unit area and larger uncertainty in their predictions. We highlight that expert opinion is needed to set boundary prediction limits to avoid unrealistically high modeling estimates. For maximizing explained variance while minimizing prediction bias, the selection of predictive algorithms for SOC mapping should consider density of available data and variability of country-specific environmental gradients. This study highlights the large degree of spatial uncertainty in SOC estimates across Latin America. We provide a framework for improving country-specific mapping efforts and reducing current discrepancy of global, regional, and country-specific SOC estimates.

Editors’ introduction Bolívar’s paper deals with evaluation in text. Her wider aim, like that of a number of other contributors here (Sinclair, Coulthard, Edge & Wharton, Scott, Thompson & Thompson, and Hunston), is to understand text as social interaction, but her starting point is the social functions agreed upon by speakers and writers in particular cultures and in particular contexts, from which she moves first to the text-type and thence to evaluation structures. The discussion of structures of evaluation itself leads this paper towards one of the other main themes running through this collection, namely the identification of text-important elements and how these can combine (Fries, Jordan, Berber Sardinha, Renouf, Darnton). If this contribution is thus coherent with the others in this volume, it is also related to others outside it, notably to those in Hunston & Thompson (2000). It is through textual change that evaluation shows itself. Thus, Bolívar’s model has three structural elements, the Lead, Follow, and Valuate, which at the same time structure the contribution and enable it to express an opinion, an evaluation of some situation or conditions in the world of phenomena. In Bolívar’s case the texts analysed happen to be newspaper editorials, in Spanish as well as English and ranging in date from 1711 to the present day, but it is through the LFV structure that evaluation can be seen to emerge. At the same time this structure is not merely linguistic (like the structure of the noun group with its pre- and post- modifiers, a structure which is purely organisational, not related to contextual conditions), but is one which is firmly rooted in and dependent on context, both social and inter-textual. In the case of conference abstracts, which she analyses later in her paper, the LFV structure is still present, if differently organised, since it reflects a different social purpose and context. Finally, Bolívar’s paper comes to meet that of Edge & Wharton, and Darnton, in that she is concerned to discover how the identification of a text pattern, à la Hoey, may further important pedagogical objectives.

In this article I examine the role of political advertisements in electoral campaigns and show aspects of the political dialogue in Venezuela since 1958, with special reference to the actors involved in the deterioration of the democratic system. The political turn-taking of the traditional parties is described briefly and then three electoral campaigns for electing a President are examined through a sample of 1496 advertisements published in El Nacional. Economic and political changes are discussed in the light of the number and class of texts published in each campaign. The turn-taking for discrediting the opponent is examined in more detail and attention is given to the multi-directional interaction through advertisements. It is claimed that these advertisements form a class of their own and, although they are indicators of the economic power of political groups, more attention must be given to the discourse of the newspaper that houses them.

En este artículo se presenta una primera aproximación al estudio del género informe de arbitraje (IA) como actividad académica fundamental en la dinámica de la investigación. Se plantea que la categorización de este género confidencial debe tomar en cuenta su relación con otros géneros en la dinámica del proceso de publicación. Se propone un marco analítico interaccional cuya categoría central es la evaluación, y que abarca los planos micro y macro (Bolívar, 2001, 2005, 2008). La aplicación de este análisis a una pequeña muestra de 25 IA revela una compleja red de interacción entre editores, árbitros y autores. El IA es caracterizado como un género del ámbito de lo privado, cuya estructura y estilo son moldeados en gran parte por las instrucciones de los editores, y por supuestos culturales sobre las relaciones interpersonales. Se discuten las implicaciones que se derivan para los estudios de los géneros discursivos, los procesos de la investigación y la escritura académica.

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