Average annual precipitation (AAP) is one of the principal environmental factors that regulates processes in terrestrial ecosystems. The effect of AAP on the availability of edaphic nutrients is poorly understood, especially in tropical zones with high rainfall. In order to evaluate the effects of high AAP on the availability of soil N, P, and K, physicochemical parameters were measured in soils of three tropical rainforests in the Chocó biogeographical region with different AAPs (7,500, 8,000, and 10,000 mm yr-1). Furthermore, a bibliographical review was carried out that including studies for distinct tropical Ultisols and AAP ranging from 1,800 to 10,000 mm yr-1. The evaluated soils presented extreme acidity with high contents of Al, organic matter (OM) and total N, and low quantities of P, Mg, and Ca. The K concentrations were intermediate and the effective cation exchange capacity (ECEC) was low. On the other hand, in the evaluation of the influence of the AAP on the availability of N, P, and K in the soil, contrasting tendencies were observed. On one side, a positive curvilinear relationship was found between the availability of N and the increase in the AAP. On the other side, the available P content significantly decreased with increasing AAP. In conclusion, the excessive AAP resulted in increases in total N and low availability of P, thereby altering the dynamics of the nutrients and the carbon balance of the tropical forest

El objetivo del presente estudio fue determinar la composición y diversidad florística arbórea a escala local en un bosque del Chocó biogeográfico, una de las regiones más lluviosas del mundo, y su relación con las características del sitio. Se emplearon dos parcelas de una hectárea, en las cuales se determinó la composición y diversidad de árboles con DAP > 10 cm y se relacionaron con los nutrientes del suelo, la topografíay el espacio. No se presentaron diferencias significativas entre las parcelas para las variables estructurales y de diversidad estudiadas, con valores de abundancia de 640 y 716 individuos/ha yde riqueza de 174 y 223 especies/ha.Nuestros resultados soportan la hipótesis de hiperdominancia de unos pocos grupos biológicos en los bosques húmedos tropicales. Ladiversidad arbórea a escala local se relacionó significativamente con algunas condiciones edáficas.Se presentó asociación positiva de la diversidad con el aluminio del suelo, y negativa con la topografía.No obstante, solamente un 37% de la variación en la composición florística fue explicada por las variables espaciales y ambientales (topográficas y edáficas). Por ello, aparentemente la distribución de las especies a escala local parece estar gobernada principalmente por procesos aleatorios o biológicos (como la limitación en dispersión), conforme lo propone la teoría neutral. El papel de las adaptaciones específicas al hábitat (teoría del nicho) pareciera ser limitado.

The net primary productivity (NPP) of tropical forests is a key process of the carbon cycle and therefore for the mitigation of global climate change. It has been proposed that NPP is limited by the availability of soil nutrients in lowland tropical forests and that belowground NPP decreases as edaphic fertility increases. This hypothesis was evaluated in two localities (Opogodó and Pacurita) of the Chocó Biogeographical region, one of the rainiest of the world, where the aboveground (litter and wood) and belowground (fine and coarse roots) components of NPP were measured. Fertility parameters (pH, nutrients, and texture) were also determined and related to NPP. Total NPP was similar between locations (23.7 vs. 24.2 t ha^-1 year^-1 for Opogodó and Pacurita, respectively). However, components of NPP showed differences: in Pacurita, with steeper topography, NPP of wood and coarse roots were higher; therefore, differences of topography and drainage between localities probably affected the NPP of wood. On the other hand, soils of Opogodó, where NPP of fine roots was higher, showed higher contents of sand, N+, and organic matter (OM). With the increase of pH, OM, N+, K, Mg, and sand, the NPP of leaves and fine roots as well as the percentage of NPP _belowground also increased, which suggests NPP limitation by multiple nutrients. The increase of NPP _belowground with the availability of edaphic nutrients evidenced a redistribution of the aboveground and belowground components of NPP with the increase of soil fertility in oligotrophic systems, probably as a mechanism to improve the capture of resources.

Nutrient recycling is a fundamental process for the functioning of tropical forests; however, anthropogenic activities such as mining could affect this process in tropical ecosystems. Given that little is known about the effects of mining on nutrient recycling in tropical forests, the objective was set to evaluate the influence of mining on nutrient cycling in tropical rainforests of the Colombian Pacific. Additionally, the hypothesis that nutrient cycling could be lower in post-mining areas was evaluated. To evaluate the effect of mining on nutrient cycling, permanent plots were established in mature and post-mining forests. In both forests, soil acidity, aluminum (Al), organic matter (OM), total nitrogen (N), available phosphorus (P), magnesium (Mg), potassium (K), calcium (Ca), and effective cation exchange capacity (ECEC) were considered. Likewise, the litter production, decomposition, and accumulation on the ground were determined; additionally, nutrient content and nutrient use efficiency (NUE) were determined. It was observed that mining influenced the nutrient contents of the soil in a different way. It was evident that total N and soil OM were similar in both forests, while the contents of P, K, Ca, Mg, Al, and ECEC available were higher in post-mining. The litterfall production and litter mass accumulation on the ground were greater in post-mining, while litter decomposition was greater in mature forests. In mature forests, there was higher foliar content of N, Ca, and B and, in addition, higher NUE of Ca. However, in post-mining, there was higher leaf content of K, Mg, P, Fe, Cu, Mn, and Zn and, in addition, greater NUE of N, P and K. In conclusion, an increase in post-mining nutrient cycling was noted as a strategy for nutrient conservation, and recovery of the functioning and maintenance of productivity in degraded Pacific ecosystems. Consequently, it is expected that in the future, if mining continues in the region, productivity and nutrient recycling will be altered.

Introducción: La restauración de ecológica es una estrategia que permite recuperar bienes y servicios de ecosistemas perturbados. Una de las actividades que genera mayor impacto en los ecosistemas forestales es la minería a cielo abierto, pues ocasiona fuertes cambios en la estructura y funcionamiento de dichos sistemas. Objetivo: El objetivo del presente trabajo fue evaluar el efecto de la edad sucesional y la distancia al bosque adyacente (bosque de referencia) sobre la estructura biológica y composición de la comunidad vegetal en minas de oro abandonadas en la selva pluvial tropical del Chocó en Colombia. Métodos: Entre junio y diciembre de 2012, y junio y octubre de 2021, se realizaron muestreos de vegetación en minas con 6, 10, 15, 19 y 24 años de abandono y en el bosque adyacente a las minas. En cada mina de distinta edad y el bosque de referencia, se establecieron cuatro parcelas de 2×50 m que fueron distribuidas de manera perpendicular al borde del bosque, a 50 m y 100 m de distancia (dos parcelas por distancia), tomando como punto de partida el borde bosque-mina (ecotono). Resultados: Se identificaron 300 especies, 193 géneros y 75 familias. La riqueza, diversidad, y equitatividad cambia poco con el tiempo de abandono en las minas pero alcanza valores superiores en el bosque de referencia. La composición de especies es similar entre las minas pero difiere sustancialmente del bosque de referencia (solo 7 % de similitud). Conclusiones: Los resultados sugieren que 24 años es poco tiempo para apreciar una recuperación sustancial de la estructura biológica y composición de la vegetación de las minas si se compara con el bosque de referencia donde la riqueza, diversidad, equitatividad son muy superiores y la composición de especies difiere sustancialmente. Aunque la distancia al bosque adyacente parece no tener efecto sobre estas variables, es claro que otros factores como la calidad del sustrato y las estrategias reproductivas de algunas especies herbáceas de las familias Cyperaceae y Melastomataceae, así como algunas arbóreas como Cespedesia spathulata y Miconia reducens, juegan un papel importante en la revegetación natural temprana de las minas abandonadas en los bosque pluviales del Chocó biogeográfico colombiano.

Environmental factors control the accumulation of aboveground biomass (AB) in tropical forests, along with the role of AB in climate change mitigation. As such, the objective of this study was to evaluate the influence of factors such as forest type, succession, abundance of individuals, species richness, height, diameter, texture, and soil nutrient levels on the AB in mature and postmining forests in Chocó, Colombia. Five plots each were set up in primary and postmining forests with 15 and 30 years of regeneration, in which the amount of AB was measured and related to the environmental factors. The AB was 178.32 t ha⁻¹ in the mature forests and 35.17 and 56.3 t ha⁻¹ after 15 and 30 years of postmining regeneration, respectively. Furthermore, the general AB level was determined by the ecosystem type, diameter, richness, abundance, Shannon evenness, and Margalef diversity. In mature forests, the AB amount was positively influenced by height and richness, and negatively influenced by dominance and evenness; in areas degraded by mining, the AB level was positively related to richness and equity, and negatively related to species diversity and soil silt. In summary, environmental factors determine the carbon storage in the forests in Chocó. Mining reduces the function of these ecosystems in mitigating climate change.