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Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change., H.R.P.P., B.K-R., and the sWorm workshops were supported by the sDiv [Synthesis Centre of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig (DFG FZT 118)]. H.R.P.P., O.F. and N.E. acknowledge funding by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 677232 to NE). K.S.R. and W.H.v.d.P. were supported by ERC-ADV grant 323020 to W.H.v.d.P. Also supported by iDiv (DFG FZT118) Flexpool proposal 34600850 (C.A.G. and N.E.); the Academy of Finland (285882) and the Natural Sciences and Engineering Research Council of Canada (postdoctoral fellowship and RGPIN-2019-05758) (E.K.C.); German Federal Ministry of Education and Research (01LO0901A) (D.J.R.); ERC-AdG 694368 (M.R.); the TULIP Laboratory of Excellence (ANR-10-LABX-41) (M.L); and the BBSRC David Phillips Fellowship to F.T.d.V. (BB/L02456X/1). In addition, data collection was funded by the Russian Foundation for Basic Research (12-04-01538-а, 12-04-01734-a, 14-44-03666-r_center_a, 15-29-02724-ofi_m, 16-04-01878-a 19-05-00245, 19-04-00-609-a); Tarbiat Modares University; Aurora Organic Dairy; UGC(NERO) (F. 1-6/Acctt./NERO/2007-08/1485); Natural Sciences and Engineering Research Council (RGPIN-2017-05391); Slovak Research and Development Agency (APVV-0098-12); Science for Global Development through Wageningen University; Norman Borlaug LEAP Programme and International Atomic Energy Agency (IAEA); São Paulo Research Foundation - FAPESP (12/22510-8); Oklahoma Agricultural Experiment Station; INIA - Spanish Agency (SUM 2006-00012-00-0); Royal Canadian Geographical Society; Environmental Protection Agency (Ireland) (2005-S-LS-8); University of Hawai’i at Mānoa (HAW01127H; HAW01123M); European Union FP7 (FunDivEurope, 265171; ROUTES 265156); U.S. Department of the Navy, Commander Pacific Fleet (W9126G-13-2-0047); Science and Engineering Research Board (SB/SO/AS-030/2013) Department of Science and Technology, New Delhi, India; Strategic Environmental Research and Development Program (SERDP) of the U.S. Department of Defense (RC-1542); Maranhão State Research Foundation (FAPEMA 03135/13, 02471/17); Coordination for the Improvement of Higher Education Personnel (CAPES 3281/2013); Ministry of Education, Youth and Sports of the Czech Republic (LTT17033); Colorado Wheat Research Foundation; Zone Atelier Alpes, French National Research Agency (ANR-11-BSV7-020-01, ANR-09-STRA-02-01, ANR 06 BIODIV 009-01); Austrian Science Fund (P16027, T441); Landwirtschaftliche Rentenbank Frankfurt am Main; Welsh Government and the European Agricultural Fund for Rural Development (Project Ref. A AAB 62 03 qA731606); SÉPAQ, Ministry of Agriculture and Forestry of Finland; Science Foundation Ireland (EEB0061); University of Toronto (Faculty of Forestry); National Science and Engineering Research Council of Canada; Haliburton Forest & Wildlife Reserve; NKU College of Arts & Sciences Grant; Österreichische Forschungsförderungsgesellschaft (837393 and 837426); Mountain Agriculture Research Unit of the University of Innsbruck; Higher Education Commission of Pakistan; Kerala Forest Research Institute, Peechi, Kerala; UNEP/GEF/TSBF-CIAT Project on Conservation and Sustainable Management of Belowground Biodiversity; Ministry of Agriculture and Forestry of Finland; Complutense University of Madrid/European Union FP7 project BioBio (FPU UCM 613520); GRDC; AWI; LWRRDC; DRDC; CONICET (National Scientific and Technical Research Council) and FONCyT (National Agency of Scientific and Technological Promotion) (PICT, PAE, PIP), Universidad Nacional de Luján y FONCyT (PICT 2293 (2006)); Fonds de recherche sur la nature et les technologies du Québec (131894); Deutsche Forschungsgemeinschaft (SCHR1000/3-1, SCHR1000/6-1, 6-2 (FOR 1598), WO 670/7-1, WO 670/7-2, & SCHA 1719/1-2), CONACYT (FONDOS MIXTOS TABASCO/PROYECTO11316); NSF (DGE-0549245, DGE-0549245, DEB-BE-0909452, NSF1241932, LTER Program DEB-97–14835); Institute for Environmental Science and Policy at the University of Illinois at Chicago; Dean’s Scholar Program at UIC; Garden Club of America Zone VI Fellowship in Urban Forestry from the Casey Tree Endowment Fund; J.E. Weaver Competitive Grant from the Nebraska Chapter of The Nature Conservancy; The College of Liberal Arts and Sciences at Depaul University; Elmore Hadley Award for Research in Ecology and Evolution from the UIC Dept. of Biological Sciences, Spanish CICYT (AMB96-1161; REN2000-0783/GLO; REN2003-05553/GLO; REN2003-03989/GLO; CGL2007-60661/BOS); Yokohama National University; MEXT KAKENHI (25220104); Japan Society for the Promotion of Science KAKENHI (25281053, 17KT0074, 25252026); ADEME (0775C0035); Ministry of Science, Innovation and Universities of Spain (CGL2017-86926-P); Syngenta Philippines; UPSTREAM; LTSER (Val Mazia/Matschertal); Marie Sklodowska Curie Postdoctoral Fellowship (747607); National Science & Technology Base Resource Survey Project of China (2018FY100306); McKnight Foundation (14–168); Program of Fundamental Researches of Presidium of Russian Academy of Sciences (AААА-A18–118021490070–5); Brazilian National Council for Scientific and Technological Development (CNPq 310690/2017–0, 404191/2019–3, 307486/2013–3); French Ministry of Foreign and European Affairs; Bavarian Ministry for Food, Agriculture and Forestry (Project No B62); INRA AIDY project; MIUR PRIN 2008; Idaho Agricultural Experiment Station; Estonian Science Foundation; Ontario Ministry of the Environment, Canada; Russian Science Foundation (16-17-10284); National Natural Science Foundation of China (41371270); Australian Research Council (FT120100463); USDA Forest Service-IITF.

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.

En suelos de sabana del estado Guárico – Venezuela, se evaluó la eficiencia de cuatro especies de hongos formadores de micorrizas nativa y su mezcla: Scutellospora pellucida, Scutellospora calospora, Glomus leptotichum y Acaulospora mellea en la toma de N y P, y su efecto en los rendimientos del cultivo de maíz hibrido HIMECA 3005 con 4 dosis de P (0, 27, 54 y 80 kg ha-1 de P2O5). Se sembró a 0,9 m entre hileras y 0,4 m entre plantas, la cuantificación del P y N foliar se hizo muestreando la hoja opuesta a la mazorca, por los métodos de Murphy – Riley y destilación con Kjeldalh; los redimientos se evaluaron en los tres surcos centrales de cada parcela. Se utilizó un diseño de bloques al azar con arregló factorial. Encontrándose que las dosis de P y los morfotipos evaluados influyeron en la toma de N y P, siendo 54 kg ha-1 de P2O5 y la mezcla de inóculos los de mejor eficiencia para la toma de N; mientras que la dosis de 54 kg ha-1 de P2O5 más Scutellospora pellucida para la toma de P. Se concluyó que estos inóculos pueden disminuir la aplicacion de P en un 25% e incrementar los rendimientos del maíz hasta en un 100% (de 2 a 4 t ha-1) con base en la producción de la zona.

rlopez@ula.ve

La asociación de los pastos cultivados Urochloa dictyoneura, Stylosanthes capitata y Centrosema macrocarpum en un suelo arenoso ácido, fertilizado con 1,0 y 0,3 Mg·ha-1 de roca fosfórica (RF) y NPK (12-24-12) respectivamente, permitió evaluar los cambios en indicadores de la fertilidad del suelo, así como el secuestro de carbono orgánico cuatro años después de iniciado el fomento agronómico. El ensayo se estableció al norte del estado Amazonas, en la localidad de Sabaneta de Guayabal, Venezuela, comparando dos tratamientos: sabana natural (SN) y sabana cultivada (SC). Se realizaron muestros de suelo a tres profundidades (0-3, 3-6 y 6-10 cm) para evaluar textura, densidad aparente, pH (1:5) en H2O y KCl, carbono orgánico del suelo (C), contenido de nitrógeno (N), fósforo total y asimilable (Pa), y bases cambiables. Los valores de pHH2O y pH KCl permitieron determinar la densidad de carga neta coloidal (DCNC). Se aplicaron análisis de varianza y pruebas de MDS para evaluar las diferencias entre tratamientos y profundidades, así como análisis de correlación entre los parámetros físicos y químicos. El tratamiento de la SC mostró cambios de la fertilidad asociados a un mayor secuestro del C del orden de 2970 kg·ha-1 en los primeros 10 cm del suelo, lo que indujo valores más electronegativos de DCNC en todas las profundidades. Este tratamiento presentó también mayor contenido de bases cambiables, N y Pa a las tres profundidades del suelo. Se concluyó que en los suelos de la sabana cultivada hubo cambios físicos, químicos y fisicoquímicos favorables en comparación con la sabana natural. Carbon sequestration and fertility changes were evaluated after four years of cover crop settlement with Urochloa dictyoneura, Stylosanthes capitata and Centrosema macrocarpum in a sandy acid soil fertilized with 1.0 and 0.3 Mg·ha-1 of phosphoric rock and NPK (12-24-12), respectively. The experiment was established at Sabaneta de Guayabal, north of Amazonas State, Venezuela, where two treatments were compared: natural (NS) and cultivated savanna (CS). Soil samples were taken at three depths (0-3, 3-6, and 6-10 cm) for determinations of texture, bulk density, 1:5 water-pH and KCl-pH, organic carbon (C), total nitrogen (N), total and available phosphorous (Pa), and exchangeable cations. The difference between the pHH2O and pH KCl allowed the determination of the colloidal charge density. Analysis were performed by ANOVA and LSD to assess differences between treatments and among depths. Correlation coefficients for the physical and chemical parameters were also obtained. The CS showed fertility changes associated with an increase of carbon sequestration of 2970 kg·ha-1 in the first 10 cm of soil, which induced higher electronegative values of the colloidal charge density in CS at the different depths. The CS also revealed higher contents of the exchangeable bases as well as N and Pa at the three different soil depths. It was concluded that in the cultivated savanna soils there were favorable physical and chemical changes in comparison with those of the natural savanna.

La quema de vegetación es una práctica frecuente en las sabanas de Trachypogon para eliminar los pastos secos y favorecer la producción de follaje con mayor valor nutritivo para el ganado. La quema de vegetación también ha sido considerada un factor fundamental para explicar el origen y mantenimiento de los ecosistemas de sabanas, en virtud de los cambios que produce en la composición florística y en el ciclaje de nutrimentos. Con el fin de determinar el efecto de la quema y el pastoreo sobre la calidad del suelo se estudiaron los cambios en características físicas, químicas y biológicas seleccionadas en muestras de suelos superficiales (0-15 cm) de un área bajo quema y pastoreo y otra protegida en donde no se practicó este manejo durante 25 años. Los resultados mostraron que en las sabanas protegidas de la quema y el pastoreo la fertilidad del suelo es mayor, debido a un pH menos ácido y más altos contenidos de materia orgánica, bases cambiables, fósforo orgánico y total, y nitrógeno total, así como una menor compactación y mayor capacidad para almacenar agua. Adicionalmente, se observó una mayor actividad microbiológica debido al mayor contenido de C y N microbiano. Burning of vegetation is a frequent management in Trachypogon savannas to eliminate dry pastures and stimulate the production of foliages with higher nutritional content. Burning of vegetation has also been considered a key factor to explain the origin and maintenance of savanna ecosystems, due to the changes produced on floristic composition and nutrient cycling. In order to determine the effects of fires and cattle raising on soil quality, we studied the changes in the top soil (0-15 cm) on selected physical, chemical and microbiological characteristics in an area under burning and cattle raising, and in another protected during 25 years. The results showed that in protected savannas soil fertility is higher due to less acid pH and higher contents of organic matter, exchangeable bases, organic and total phosphorus, and nitrogen, along with lower compaction and higher water holding capacity. Additionally, a higher microbiological activity due to a higher microbial C and N was observed.

101-117 dlopez@strix.ciens.ucv.ve semestral Referencia analítica

13-23 dlopez@strix.ciens.ucv.ve emedina@ivic.ve semestral Referencia analítica

69-80 unesr67@reacciun.ve dlopez@strix.ciens.ucv.ve semestral Referencia analítica

Las sabanas de Sudamérica con una superficie de 269×106ha extendidas en Brasil, Colombia, Venezuela, Guyana y Bolivia representan una de las mayores extensiones de tierra con potencial para la producción agrícola, constituyéndose en la principal alternativa para evitar la expansión agrícola hacia áreas de mayor fragilidad ecológica. Hasta hace unos 40 años estas sabanas estuvieron muy poco afectadas por la actividad antrópica, dedicándose principalmente a la ganadería extensiva. En los últimos 40 años las pasturas nativas de bajos requerimientos nutricionales están siendo reemplazadas por pastos africanos principalmente de los géneros Brachiaria y Andropogon. Igualmente, ha ocurrido una reforestación extensiva para producción de madera y papel con especies introducidas de Pinos y Eucaliptos que se adaptan muy bien a las condiciones agroclimáticas del trópico bi-estacional. La introducción de pastos y de cultivos anuales y perennes en sabanas ha sido posible solo, bajo un esquema de fertilización (N, P, K y encalado). Aunque las modificaciones al paisaje introducidas por los nuevos usos de la tierra son ahora en sitios alejados de los grandes centros urbanos y relativamente poco perceptibles, si se toma en consideración las grandes extensiones de tierras de sabanas que están siendo afectadas y las que lo serán por formar parte de proyectos agrícolas, será inevitable una modificación profunda de esos biomas. En este trabajo se hace una revisión preliminar comparativa del proceso de colonización agrícola en los llanos y cerrados. En la necesidad de generar indicadores ligados a los procesos biogeoquímicos afectados, se presentan tres estudios de casos para sabanas venezolanas. South American savannahs cover a surface of 269×106ha in Brazil, Colombia, Venezuela, Guyana and Bolivia. In a world scale savannahs are one of the most important land extensions with agricultural potential for crop and forestry production. These territories also constitute the main alternative to agricultural expansion into ecologically fragile tropical areas such as tropical rainforests and hillsides. Forty years ago anthropic activity had little effect on Latin American savannahs, since they were used for extensive cattle raising. In the last four decades, however, the natural herbaceous vegetation with low nutrient requirements in the savannahs (llanos) of Colombia and Venezuela, as well as in the Cerrado (Brazil) has been replaced by introduced African pastures, particularly from the genera Brachiaria and Andropogon. Furthermore, intensive reforestation programs for timber and pulpwood commercialization have introduced species able to cope with the environmental conditions, such as Pinus and Eucaliptus. The introduction of African pastures and annual and perennial crops has been possible with fertilization (N, P, K and lime). The landscape modifications caused by these land uses are usually far from the urban areas and are still considered to be low. However, if the entire land surface currently affected by agriculture and agroforestry use and the land yet to be incorporated into projects is taken into consideration, a profound modification is expected to occur in these biomes. Herein is presented a preliminary comparative review of the agricultural colonization processes in the Llanos and Cerrados. In the need to generate indicators related to biogeochemical processes, three case studies from Venezuelan savannahs are presented. As savanas de Sul América com uma superfície de 269×106ha estendidas no Brasil, Colômbia, Venezuela, Guiana e Bolívia representam uma das maiores extensões de terra com potencial para a produção agrícola, constituindo-se na principal alternativa para evitar a expansão agrícola para áreas de maior fragilidade ecológica. Ha 40 anos atrás estas savanas estiveram muito pouco afetadas pela atividade antrópica, dedicando-se principalmente à criação extensiva de gado. Nos últimos 40 anos as pastagens nativas de baixos requerimentos nutricionais estão sendo substituídas por pastagens africanas principalmente dos gêneros Brachiaria e Andropogon. Igualmente, tem ocorrido um reflorestamento extensivo para produção de madeira e papel com espécies introduzidas de Pinheiros e Eucaliptos que se adaptam muito bem às condições agro climáticas do trópico bi-estacional. A introdução de pastagens e de cultivos anuais e perenes em savanas tem sido possível somente, sob um esquema de fertilização (N, P, K e encalado). Embora as modificações à paisagem introduzidas pelos novos usos da terra sejam agora em lugares afastados dos grandes centros urbanos e relativamente pouco perceptíveis, se levamos em consideração as grandes extensões de terras de savanas que estão sendo afetadas e as que serão por formarem parte de projetos agrícolas, será inevitável uma modificação profunda desses biomas. Neste trabalho se faz uma revisão preliminar comparativa do processo de colonização agrícola nas planícies e cerrados. Na necessidade de gerar indicadores ligados aos processos bio geoquímicos afetados, se apresentam três estudos de casos para savanas venezuelanas.

3-8 ihernand@strix.ciens.ucv.ve dlopez@strix.ciens.ucv.ve semestral Referencia analítica

Se presenta un modelo conceptual del funcionamiento de suelos de los Llanos Centrales Venezolanos, basado en las relaciones de estructura del suelo y de las fracciones activas y estabilizadas de la materia orgánica, que muestra cómo cambian los procesos del suelo según el manejo agronómico. Se consideran dos tipos de labranzas contrastantes, la siembra directa sin labranza y con presencia de una cobertura vegetal, y la labranza convencional con fuerte mecanización para romper el suelo y enterrar cualquier tipo de cobertura o residuo. Se consideran variables externas (labranza y coberturas), variables de estado (fracciones de materia orgánica) y los procesos involucrados. Dada la acidez de los suelos, su baja fertilidad con limitaciones para el uso agrícola, y su uso cada vez mayor para producción de cereales, en especial maíz, se discuten los cambios en las fracciones de la materia orgánica por la intensidad de la labranza y la ubicación de los residuos vegetales, aspectos que influyen en la producción de CO2 contribuyendo al efecto invernadero y que, por otra parte, pueden intensificar los procesos de erosión y pérdida de nutrimentos, agravando los problemas de fertilidad y de degradación de los suelos. El sistema convencional de labranza aumenta la liberación de CO2 e intensifica la degradación del suelo, disminuyendo la materia orgánica. Alternativamente, la siembra directa es conservacionista e incrementa los compartimientos activos y lentos que son fuente potencial de nutrimentos, aumentando la fertilidad a mediano plazo, los procesos de descomposición microbiana son más lentos y las emisiones de CO2 más bajas. El modelo de siembra directa es parecido al modelo de sabana virgen, tanto en las variables de estado relacionadas con la conservación como en los procesos de pérdida o conservación, siendo una alternativa de manejo que permite el uso más sostenido de los suelos de sabana. A conceptual model of soil performance in the Venezuelan Central Plains is presented, based on the relations between soil structure and active and stabilized fractions of the organic matter. It shows how soil processes change with agronomic handling. Two contrasting types of farming are considered, direct sowing without tillage and with the presence of a vegetal cover, and conventional farming with strong mechanical procedures to break the soil and bury any kind of cover or residue. External variables (tillage and covers), state variables (organic matter fractions) and the processes involved are considered. Given the soil acidity, its low fertility with limitations for agricultural use and its ever increasing use for production of cereals, mostly maize, the changes in organic matter fractions due to tillage intensity and the location of vegetal residues are discussed. The latter aspects influence CO2 production, contributing to the greenhouse effect, and can also intensify erosion processes and nutrient losses, aggravating problems of fertility and soil degradation. The conventional farming process increases CO2 liberation and intensifies soil degradation, reducing organic matter. Alternatively, direct sowing is conservationist; it increases active and slow compartments which are potential sources of nutrients, improving fertility in the medium term, microbial decomposition processes are slower, and CO2 emissions are lower. The direct sowing model resembles the virgin savanna model, both in state variables related to conservation and in processes of loss and conservation, being an alternative that leads to a more sustained use of savanna soils. Apresenta-se um modelo conceitual do funcionamento de solos de Los Llanos Centrais Venezuelanos, baseado nas relações de estrutura do solo e das frações ativas e estabilizadas da matéria orgânica, que mostra como mudam os processos do solo segundo o manejo agronómico. Consideram-se dois tipos de lavouras contrastantes, a sembra direta sem lavoura e com presença de uma cobertura vegetal, e a lavoura convencional com forte mecanização para romper o solo e enterrar qualquer tipo de cobertura ou resíduo. Consideram-se variáveis externas (lavoura e coberturas), variáveis de estado (frações de matéria orgânica) e os processos involucrados. Devido a acidez dos solos, sua baixa fertilidade com limitações para o uso agrícola, e seu uso cada vez maior para produção de cereais, especialmente milho, discutem-se as mudanças nas frações da matéria orgânica pela intensidade da lavoura e a localização dos resíduos vegetais, aspectos que influem na produção de CO2 contribuindo ao efeito invernação e que, por outra parte, podem intensificar os processos de erosão e perda de nutrimentos, agravando os problemas de fertilidade e de degradação dos solos. O sistema convencional de lavoura aumenta a liberação de CO2 e intensifica a degradação do solo, diminuindo a matéria orgânica. Alternativamente, a plantação direta é conservacionista e incrementa os compartimentos ativos e lentos que são fonte potencial de nutrimentos, aumentando a fertilidade a mediano prazo, os processos de descomposição microbiana são mais lentos e as emissões de CO2 mais baixas. O modelo de plantação direta é parecido ao modelo de savana virgem, tanto nas variáveis de estado relacionadas com a conservação como nos processos de perda ou conservação, sendo uma alternativa de manejo que permite o uso mais sustentável dos solos de savana.