Climate and land management affect nutrient cycling in grassland ecosystems. We aimed to understand whether temperate and tropical grasslands differ in terms of soil organic carbon (SOC), nitrogen (N), and phosphorus (P) concentrations, and their C:N:P stoichiometric ratios in grazed and ungrazed natural grasslands and pastures. For this, we used a meta-analysis approach (1296 records, 241 papers), and regression models to explain the observed patterns in terms of mean annual precipitation (MAP), mean annual temperature (MAT), altitude, and latitude. SOC, N, and P concentrations were higher in temperate regions than in tropical ones, and they negatively correlated with MAT and MAP. The grassland type effect was more significant for tropical regions. In tropical regions, soil C:N ratios were higher in ungrazed than in grazed pastures, and soil N:P ratios in ungrazed sites were higher in pastures than in natural grasslands. Grazing increases soil N and SOC for natural grasslands in temperate regions. Our findings suggest that soil stoichiometric C:N:P stoichiometric signatures in grasslands differed between tropical and temperate regions on a global scale. P is a key element in regulation and restriction on soil C and N cycling in tropical regions but less in the temperate ones. Our findings suggest the direction of effects of grazing or grassland type on C:N:P stoichiometric signature. Since imbalances in soil stoichiometric ratios may have implications for ecosystem functioning, the assessment of these patterns could serve as a valuable tool for management and conservation of grasslands and pastures in both tropical and temperate regions.

Today humanity faces several complex problems, two of which are global warming and the loss of biological diversity. An agroecological matrix approach, conceives the territory as patches of natural and cultivated vegetation, interconnected to maintain watershed integrity. Many ethnic groups maintain a high biological heterogeneity as in the case of the agrological matrix. This study analyzed features and trends in a specific agroecological matrix, integrating local and scientific knowledge with environmental and social information, as a complex system. For the last 15 years we studied agroecological spaces used by the Ntaj’uy (Zoque-Popoluca) people in Los Tuxtlas, Veracruz, Mexico. Participatory methods were used to understand social interactions and land management decisions. Ecology field methods allowed us to assess soil loss, litter production, water quality, and vegetation structure. Soil erosion, vegetation fragmentation and social marginalization are the most important problems in the region; the tropical sub-evergreen forest has decreased by about 60%, the deciduous forest is down by 80%, and cultivated pastures have increased over 400%. Coffee and milpa agroecosystems could be improved, through product diversification, along with interconnectivity among vegetation patches, to prevent environmental degradation, and improve conditions to reach food sovereignty and income diversification, in a context of Ntaj’uy self-determination in their territories.

Se estudió el conocimiento etnobotánico y se analizaron aspectos ecológicos de plantas utilizadas como antiviperino por tres curanderos de la región de Acayucan, Veracruz, México. Los objetivos fueron conocer las plantas usadas para la elaboración del suero y evaluar la estructura general de la vegetación en dos áreas en donde se recolectan estas plantas. Se llevaron a cabo entrevistas y recorridos de campo con los tres curanderos, se calcularon las frecuencias relativas de las especies y se registró su forma de uso. La estructura de la vegetación se estudió en sitios de 400 m2 divididos en parcelas de 25 m2. Se determinaron 16 especies usadas contra la mordedura de serpiente. Las plantas se preparan de tres formas: cocimiento, pulverización y extracto alcohólico; todos los métodos se aplican vía oral. Las zonas de recolección son áreas muy aisladas y fragmentadas, rodeadas por terrenos utilizados para la agricultura y la ganadería.

Aim of the study: The aim of this work was to isolate consortia of arbuscular mycorrhizal fungi (AMF) associated to Liquidambar styraciflua in soils of the Santa Marta Mountain in Veracruz, and to select highly effective mycorrhizal consortia on promoting the growth of four tree forest species with economic and ecological importance.Area of study: Santa Marta Mountain, inside the buffer area of the Los Tuxtlas Biological Reserve in Veracruz (México).Materials and methods: Ten composite samples of rhizosphere soil were collected from L. styraciflua trees of 13-15 cm DBH (diameter at breast height). Roots were fixed in FAA solution to determine the mycorrhizal colonization percentage, the abundance of morphospecies, and its effectiveness in promoting the growth of L. styraciflua, Terminalia amazonia, Cordia alliodora, and Cojoba arborea. Soil physical and chemical characteristics were also analysed, and soil type recognition was performed with the Reference Base for Soil FAO-ISRIC World-SICS. Mycorrhizal colonization was determined by the method of clearing and staining roots with trypan blue; total percentage of colonization was estimated by the Linderman-Biermann method. Spores were extracted for counting and identifying morphospecies from each soil sample, those with more effectiveness were selected and inoculated in the four tree species, based upon a completely random design there were evaluated height, number of leaves, total dry weight and foliar area.Main results: Average mycorrhizal colonization percentage was 45% from natural conditions, samples one and four showed 80% of AMF-colonization. Average number of spores was 617 in 100 g-1 of dry soil. Forty-seven AMF-morphospecies were identified. After eight months significant differences were observed in root colonization, height, number of leaves, total dry weight, leaf area and foliar analysis of N5+, P5+ and K+ on plants inoculated with rhizosphere samples of L. styraciflua. Terminalia amazonia and Cojoba arborea showed greater response to the inoculation of AMF, they showed more height, number of leaves and more total dry weight; whereas C. alliodora appears to be low dependent on AMF.Highlights: Diversispora aurantia and Glomus aggregatum are reported by the first time from Mexican humid tropics. Native AMF have potential biotechnological application. The mycorrhizal consortium six (Glomus and Acaulospora) was the more effective in promoting the development of the four tree species used in the experiment.

Objetivo: El objetivo fue evaluar el crecimiento y la acumulación de biomasa en plántulas de Cedrela odorata, Tabebuia chrysantha (especie amenazada) y T. rosea, utilizando fertilizantes sintéticos y basados en microorganismos, así como su efecto rizosférico. Diseño/metodología/enfoque: Se estableció un diseño completamente al azar con cuatro réplicas, evaluando tres tratamientos y un control a plántulas de tres especies forestales: T1, biofertilizante con micorrizas; T2, biofertilizante a base de Azospirillum sp.; T3, fertilizante de liberación lenta, usando de la semana uno a la cuatro la fórmula comercial de arranque 10-15-5, aplicando 50ppm/planta; mientras que la semana 10 a la 12, se utilizaron 100ppm/planta de Nitro® 30-0-0, con sus correspondientes controles. La variable de respuesta (crecimiento), se midió la altura cada diez días y se estimó la biomasa acumulada a las 12 semanas. Para finalizar se tomaron muestras de suelo rizosférico de cada tratamiento, por especie y se cultivaron Bacterias Fijadoras de Nitrógeno de Vida Libre (BFNVL) en agar rojo Congo. Resultados: El biofertilizante con Azospirillum sp. fue el tratamiento que mejoró el crecimiento de las plántulas y la calidad microbiológica del suelo rizosférico de Cedrela odorata y Tabebuia rosea; mientras que con T. chrysantha, no se encontraron diferencias estadísticamente significativas entre los diferentes tipos de fertilización. El crecimiento de BFNVL fue favorecido por los biofertizantes. Limitaciones del estudio/implicaciones: El estudio duró tres meses, por ello se sugiere analizar estas variables a largo plazo y su respuesta en campo. Hallazgos/conclusiones: La biofertilización puede ser una alternativa para el crecimiento de especies forestales como Cedrela odorata y Tabebuia rosea.