Resumen Se realizó una comparación interanual de la producción mensual de hojarasca de un bosque seco tropical (BsT) tardío en el Parque Nacional Santa Rosa. La producción de hojarasca promedio anual para tres años (6.7 ton/ha/año) indica que el sitio tiene un valor de producción en los rangos medio para BsT tropical tardío según la literatura. También se encontró que la estación seca concentra un 57% de volumen de biomasa de hojarasca. La relación de biomasa de hojas y otros residuos foliares fue de 56% y 44% correspondientemente para un año de análisis. No se encontró una correlación significativa entre variables climáticas anuales con la producción de hojarasca, pero hay claras evidencias que los años con estación de crecimiento más larga y con los menores déficits hídricos de evapotranspiración fueron los de mayor productividad.

Abstract An interannual comparison of monthly litterfall production was conducted in a late successional stage of a tropical dry forest (TDF) in the Santa Rosa National Park. According to the literature, the annual average litterfall production of three years (6.7 tons/ha/year) indicates that the site has a production value in the intermediate ranges for TDF. It was also found that the dry season produces 57% of the volume of litterfall biomass. The biomass ratio of leaves and foliar components was 56% and 44%, correspondingly, for one year of analysis. No direct relationship was found between annual climatic variables and litterfall production. However, there is clear evidence that the years with the most extended growth season and the smaller evapotranspiration deficits have the highest litterfall productivity.

Resumen Introducción: La producción de hojarasca, la dinámica de nutrientes foliares y la descomposición son esenciales para mantener el ciclo de nutrientes, la fertilidad del suelo y la regulación del carbono en ecosistemas terrestres. Con diversos estudios que abordan estos procesos, su variación en los bosques secos tropicales (BSTs) permanece incierta, por su compleja interacción de factores bióticos y abióticos. Objetivo: Evaluar la caída de hojarasca, el retorno potencial de nutrientes y eficiencia de uso, y la variación en descomposición en un gradiente sucesional de un BST en Tolima, Colombia. Métodos: Cuantificamos la caída de hojarasca entre noviembre 2017 y octubre 2019 en 12 parcelas distribuidas en cuatro estados sucesionales: bosque inicial, temprano, intermedio y tardío. Identificamos las especies arbóreas clave en la producción de hojarasca y caracterizamos la descomposición foliar de estas especies. A nivel comunitario, cuantificamos el retorno potencial de C, N y P, la eficiencia de uso de N y P y la relación C:N y N:P. Posteriormente, analizamos las relaciones entre las características de la vegetación y algunas propiedades químicas del suelo con estos procesos ecológicos. Resultados: Encontramos que la caída total de hojarasca en los bosques tardíos (8.46 Mg ha-1 año-1) fue el doble de la hallada en bosques iniciales (4.45 Mg ha-1 año-1). La descomposición fue mayor en bosques iniciales (k = 1.28) en comparación con bosques intermedios (k = 0.97) y tardíos (k = 0.87). El retorno potencial de nutrientes no cambió con el avance de la sucesión vegetal, pero exhibió diferencias entre los sitios de estudio. El desarrollo estructural y la riqueza de especies favorecieron la caída de hojarasca, mientras que las condiciones químicas del suelo influyeron en el retorno de nutrientes y descomposición. Conclusiones: Los BSTs tienen la capacidad de recuperar la función ecosistémica de aporte de hojarasca fina, retorno y liberación de nutrientes después del cese de alteraciones antrópicas; sin embargo, la calidad del suelo es fundamental en el retorno y liberación de nutrientes.

Abstract Introduction: The litterfall production, foliar nutrient dynamics and decomposition are essential to maintain nutrient cycling, soil fertility, and carbon regulation in terrestrial ecosystems. With several studies addressing the variation of these processes, their dynamics in tropical dry forests (TDFs) remain unclear, due to its complex interaction of biotic and abiotic factors. Objective: To evaluate litterfall, nutrient potential return and use efficiency, and decomposition variation in a TDF successional gradient in Tolima, Colombia. Methods: We quantified litterfall from November 2017 to October 2019 in 12 plots distributed in four successional stages: initial, early, intermediate, and late forests. We identified key tree species in foliar litter production and characterized the foliar decomposition of these species. At the community level, we quantified the C, N and P potential return, the N and P use efficiency, and the C:N and N:P ratio. Subsequently, we analyze relationships between vegetation characteristics and some soil chemical properties with these ecological processes. Results: We found that total litterfall in late forests (8.46 Mg ha-1 y-1) was double that found in initial forests (4.45 Mg ha-1 y-1). Decomposition was higher in initial (k = 1.28) compared to intermediate (k = 0.97) and late forests (k = 0.87). The nutrient potential return didn't change along succession, but it did show differences between study sites. The structural development and species richness favored litterfall, while soil chemical conditions influenced nutrient returns and decomposition. Conclusions: TDFs could recover key ecosystem function related to litterfall and nutrient dynamics after disturbances cessation; however, the soil quality is fundamental in return and release of nutrients.

Abstract This study evaluates litterfall production, forest floor mass and leaf-litter decomposition and growth in an 8-year- old Eucalyptus grandis stand and 467 treesha-1 and in another 16-year-old Pinus elliottii stand with 533 treesha-1, in the northeast of Corrientes, Argentina. In each stand, three permanent plots of 1000 m2 were established. Four collectors of 1.0 m2 and 12 litterbags of 20 cm2 were randomly distributed in each plot. The measurements were made over 3 years. The relationship between environmental factors and leaf-litterfall was analyzed using the Pearson correlation coefficient (r). The E. grandis stand showed an annual increment (IMA) of 25.2 m3ha-1year-1, a mean annual litter production (PAL) of 10.1 Mgha-1, an annual decomposition constant (K) of 0.7 and a half-life time (THL) of 1.0 years. The P. elliottii stand presented an IMA of 26.1 m3ha-1year-1, a PAL of 14.3 Mgha-1, a K of 0.6 and a THL of 1.15 years. The highest material fall occurred during the summer for both species with maximum monthly mean values of 1.5 Mgha-1 for E. grandis and 2.3 Mgha-1 for P. elliottii. The leaves were the most representative component of the fallen material. The climatic variable that presented the highest correlation with material fall was the average monthly temperature. The dynamics observed in the stands, production, formation of mulch and its decomposition are characteristic of subtropical forests.

Resumen Este estudio evalúa la producción de hojarasca, la acumulación y descomposición del mantillo y el crecimiento en un rodal de Eucalyptus grandis de 8 años de edad y 467 árbolesha-1 y en otro de Pinus elliottii de 16 años de edad y 533 árbolesha-1, en el nordeste de Corrientes, Argentina. En cada rodal fueron instaladas 3 parcelas permanentes de 1000 m2. Se distribuyeron 4 canastos de 1,0 m2 y 12 litterbags de 20 cm2, por parcela. Las mediciones fueron realizadas durante 3 años. La relación entre factores ambientales y caída de hojarasca se analizó mediante el coeficiente de correlación de Pearson (r). El rodal de E. grandis presentó un incremento medio anual (IMA) de 25,2 m3ha-1año-1, una producción de hojarasca anual media (PHA) de 10,1 Mgha-1, una constante de descomposición anual (K) de 0.7 y un tiempo de media vida (TMV) de 1,0 año. El rodal de P. elliottii presentó un (IMA) de 26,1 m3ha-1año-1, PHA de 14,3 Mgha-1, K de 0,6 y un TMV de 1,15 años. La mayor caída de material se presentó durante el verano para ambas especies con valores medios mensuales máximos de 1,5 Mgha-1 para E. grandis y de 2,3 Mgha-1 para P. elliottii. Las hojas fueron el componente más representativo del material caído. La variable climática que presentó mayor correlación con la caída de material fue la temperatura media mensual. La dinámica observada en los rodales, producción, formación de mantillo y su descomposición es característica de los bosques subtropicales.

Resumen Introducción. Los sistemas de producción tradicionales de ganadería generan degradación de suelos, por lo cual es importante implementar sistemas silvopastoriles como una alternativa para la producción bovina de carne y leche. Objetivo. Cuantificar la producción de hojarasca foliar de especies leñosas perennes (Gmelina arborea - Melina, Tabebuia rosea - Roble, Acacia mangium – Acacia) y el aporte potencial de nutrientes al suelo (ciclaje de nutrientes) dentro de sistemas silvopastoriles. Materiales y métodos. Se evaluó la producción y descomposición de hojarasca de especies forestales en campos sembrados con una variedad de gramínea del género Brachiaria, en el Valle medio del Sinú, Colombia, durante mayo a septiembre de 2013. Se utilizó un diseño en bloques completos al azar con tres repeticiones. Los tratamientos utilizados fueron Pr= Brachiaria híbrido cv. Mulato II, SSP1 = Tabebuia rosea + Brachiaria cv. Mulato II, SSP2= Acacia mangium + Brachiaria cv. Mulato II y SSP3= Gmelina arborea + Brachiaria cv Mulato II. Resultados. Hubo mayor producción de hojarasca en especies forestales dentro de los sistemas silvopastoriles. La especie forestal G. arborea obtuvo los mayores aportes potenciales de nutrientes en la hojarasca con el siguiente patrón descendente en kg ha-1: C 4069,6 > Ca 96,47 >N 62,46 > K 37,48 > Mg 23,60 > P 14,57. La hojarasca de la pastura Mulato II y la especie forestal G. arborea exhibieron mayor velocidad de descomposición (k= 1,87 y k=1,77, respectivamente) que el resto de las especies evaluadas. Conclusiones. Las especies forestales evaluadas mejoraron la calidad del suelo mediante un mayor aporte de hojarasca y un mayor aporte potencial de nutrientes.

Abstract Introduction. Traditional livestock production systems generate soil degradation, so it is important to implement silvopastoral systems as an alternative for meat and dairy cattle production. Objective. To quantify the production of leaf litter of perennial woody species (Gmelina arborea - Melina, Tabebuia rosea - Oak, Acacia mangium - Acacia) and the potential contribution of nutrients to the soil (nutrient cycling) within silvopastoral systems. Materials and methods. The production and decomposition of leaf litter of forest species was evaluated in fields planted with a variety of grasses of the genus Brachiaria, in the middle Sinu valley, Colombia, during May to September 2013. A randomized complete block design with three replications was used. The treatments used were Pr= Brachiaria hybrid cv. Mulato II, SSP1= Tabebuia rosea + Brachiaria cv. Mulato II, SSP2= Acacia mangium + Brachiaria cv. Mulato II, and SSP3= Gmelina arborea + Brachiaria cv. Mulato II. Results. The greater production of leaf litter in forest species within the silvopastoral systems was evidenced. The forest species G. arborea had the highest potential nutrient inputs in litterfall with the following descending pattern in kg ha-1: C 4069,6> Ca 96,47> N 62,46> K 37,48> Mg 23,60> P 14,57. Mulato II pasture litter and the forest species G. arborea exhibited higher decomposition rates (k= 1.87 and k=1.77, respectively) than the rest of the species evaluated. Conclusions. The forest species evaluated improved soil quality through a higher leaf litter input and a higher potential nutrient input.

Resumen Antecedentes: Los almacenes de carbono (C) de los bosques del mundo ascienden a 861 Pg; 44 % se encuentra en el suelo. A pesar de su importancia como reservorio, los estudios sobre carbono orgánico en el suelo (COS) en los bosques de México son escasos. Pregunta: ¿El carbono orgánico en el suelo varía entre tipos de vegetación y tipos de suelo en los bosques de Durango? Sitio de estudio: Bosques templados de Durango, México. Métodos: Los datos de COS se obtuvieron de 399 sitios permanentes. Se colectaron muestras de hojarasca, horizonte de fermentación y de las capas de suelo de 0-30 y 30-60 cm. Los contenidos de C se determinaron en un analizador elemental. El cálculo de las incertidumbres se realizó siguiendo los procedimientos usados por la Comisión Nacional Forestal. Resultados: El COS promedio estimado fue 8.48, 1.08, 110.62 y 53.44 Mg ha-1 en hojarasca, horizonte de fermentación, suelo de 0-30 y de 30-60 cm, respectivamente. Los almacenes promedio de C total en el suelo oscilaron desde 26.34 hasta 578.27 Mg ha-1 (incertidumbre: 6.31 %). La mayor variabilidad de los almacenes de COS se presentó en el bosque de pino. Conclusiones: El tipo de bosque no influye en los almacenes de carbono orgánico en el suelo, pero sí el tipo de suelo. Los reservorios de COS en los bosques Durango son más altos comparados con el mismo tipo de vegetación en otras regiones del país.

Abstract Background: Carbon (C) stocks in the world's forests amount to 861 Pg; 44 % is in the soil. Despite its importance as a reservoir, studies on soil organic carbon (SOC) in forests of Mexico are scarce. Questions: Does soil organic carbon vary between vegetation types and soil types in Durango forests? Study site: Temperate forests of Durango, Mexico. Methods: SOC data were obtained from 399 permanent sites. Samples were collected from leaf litter, fermentation horizon and from the 0-30 and 30-60 cm soil layers. C contents were determined on an elemental analyzer. Uncertainties were calculated following the procedures used by the National Forestry Commission. Results: The average SOC was 8.48, 1.08, 110.62 and 53.44 Mg ha-1 in litter, fermentation horizon, 0-30 and 30-60 cm soil, respectively. The average total soil C stocks ranged from 26.34 to 578.27 Mg ha-1 (uncertainty: 6.31 %). The greatest variability of SOC stocks occurred in pine forest. Conclusions: Forest type does not influence soil organic carbon pools, but soil type does. SOC pools in Durango forests are higher compared to the same type of vegetation in other regions of the country.

ABSTRACT The ecological structure of forest fragments is closely related to the dynamics of biological flows directly dependent on the decomposition of the litterfall, which is the main mechanism of recycling nutrients to plants. In this sense, the objective of the present work was to quantify the annual litterfall productionduring the period from April 2013 to March 2014 in Mata do Bebo, an Atlantic Forest fragment located in Macaíba, Rio Grande do Norte. 10 conical collectors were used to obtain the data on the litter contribution, with an average opening area of 0.128 m2, placed 1 m above the ground. The material was collected monthly, dried at air temperature for 48 h, and separated into four fractions: leaves, bark and branches, reproductive material; and miscellaneous material. After separation, the fractions were weighed and stored. The total contribution of litter was uninterrupted and totaled 5,038.72 kg ha-1 yea-1, with the highest production in September, at the beginning of the dry season, and the lowest in July. The foliar fraction made the largest contribution, with 3,744.26 kg ha-1 yean1, followed by the reproductive material, which reached 846.29 kg ha-1 year-1, branches and bark, with 396.10 kg ha-1 year-1, and miscellaneous material, with 52,069 kg ha-1 year-1. The correlations of litterfall production with rainfall and temperature were negative. The litterfall production in the fragment was lower than that obtained in other remaining Atlantic Forest areas, possibly because it is located in a region considered an ecotone between the Caatinga and Atlantic Forest biomes, besides the anthropic effect to which it has been submitted for decades.

RESUMEN La estructura ecológica de un fragmento de bosque está estrechamente relacionada con la dinámica de los flujos biológicos, ya que depende directamente de la descomposición de la hojarasca, que representa el principal mecanismo de disponibilidad y retorno de nutrientes a las plantas. El objetivo de este trabajo fue cuantificar la producción anual de hojarasca en un fragmento de Bosque Atlántico en el noreste de Brasil. Para obtener datos sobre la producción de hojarasca se utilizaron 10 colectores cónicos con una superficie media de 0,128 m 2 , situados a 1 m de altura. El material se recogía mensualmentg, se secaba a temperatura ambiente durante 48 h y se separaba en fracciones: hojas, corteza, ramas, material de reproducción y miscelánea. Después de la separación las fracciones fueron pesadas y almacenadas. La producción de hojarasca fue ininterrumpida y ascendió a un total de 5.038,72 kg ha -1 .año~ 1 , con la mayor producción en septiembre, al comienzo del período seco, y la menor en julio. La fracción foliar fue la que presentó el mayor aporte en la producción de la hojarasca, con 3.744,26 kg ha -1 año- 1 , seguida del material de reproducción que alcanzó a 846,29 kg ha -1 año -1 , las ramas y las cáscaras con 396,10 kg ha -1 añoy material misceláneo con 52.069 kg ha -1 año -1 . Las correlaciones de la producción de hojarasca con la lluvia y la temperatura resultaron negativas. La producción de hojarasca en el fragmento fue menor que la obtenida en otras zonas del Bosque Atlántico, posiblemente porque se encuentra en una región considerada un ecotono con la Caatinga, además del efecto antrópico al que ha estado sometido durante décadas.

RESUMEN: La hojarasca tiene valores fundamentales de carbono acumulado en su biomasa, con una participación esencial en todo el sistema forestal, tanto, para la captura de carbono como para los beneficios al ciclo biogeoquímico en el suministro de la demanda nutricional del suelo. El objetivo de este estudio fue evaluar las características de la hojarasca de clones de eucalipto en relación con el aporte de biomasa, carbono y nutrientes en cada una de sus fracciones formadoras en un sistema de producción integrado a los 10 años de edad. Se evaluó la producción acumulada de hojarasca de dos híbridos, Eucalyptus urophylla x E. grandis (AAC 645) y E. urophylla x E. camaldulensis (AAC 33). La colecta se realizó en áreas de 1 m 2 para cada clon y se evaluó la biomasa de hojarasca acumulada, el contenido de carbono, el contenido de nutrientes y el stock de cada componente de la hojarasca. El clon AAC 645 tuvo la biomasa de hojarasca y el stock de carbono más altos. La fracción de ramas en ambos clones mostró mayores promedios de biomasa y carbono acumulado, así como soporte nutricional. El clon AAC 645 presentó mayor contenido de nutrientes totales, excepto Ca, Mg y S.

ABSTRACT: Litter has fundamental carbon values accumulated in its biomass, with an essential participation in the whole forest system for both carbón sequestration and for the benefits to the biogeochemical cycle in supplying the soil's nutritional demand. This study aimed to evaluate the litter characteristics of eucalyptus clones regarding the contribution of biomass, carbon, and nutrients in each of its forming fractions in an integrated production system at 10 years of age. The accumulated litterfall production of two hybrids, Eucalyptus urophylla x E. grandis (AAC 645) and E. urophylla x E. camaldulensis (AAC 33), was evaluated. The collection was carried out in 1 m2 plots for each clone, and the accumulated litter biomass, carbon content, nutrient content, and stock of each litter component were evaluated. Clone AAC 645 had the highest litter biomass and carbon stock. The branch fraction in both clones showed higher biomass accumulated carbon averages, and nutritional support. Clone AAC 645 had higher total nutrient content, except for Ca, Mg, and S.

ABSTRACT Afforestation of sites disturbed after bauxite mining is the favorite technique to restore all ecosystem functions. The nature of the tree species used for revegetation of post-mining land can accelerate the recovery of soil organic matter and nutrient cycles. This study aimed to determine the litterfall production, decomposition rate and nutrient content from three types of forest cover ( Eucalyptus , Anadenanthera peregrina , mixed plantation of 16 native species) planted in a bauxite mining area in recovery. Litterfall production was evaluated monthly over 30 months, and the litter mass was assessed twice a year (dry and rainy periods). Total nutrient content was determined from samples grouped by period (dry and rainy). The annual average values for litterfall dry mass and litter mass were higher in Eucalyptus and mixed native. The period (dry or rainy) did not influence litterfall rates in A. peregrina , but Eucalyptus and mixed native presented higher amounts for litterfall during the rainy and dry periods, respectively. Litter accumulation in Eucalyptus was not affected by the season of the year, but mixed native and A. peregrina presented higher litter accumulation in the dry season. Apparent decomposition rates of A. peregrina and mixed native were higher in the rainy season, highlighting the A. peregrina with the highest values compared with the other forest covers. The mixed native presented the highest leaf content of P, K, Ca and Mg in both the litterfall and litter mass, while Eucalyptus had the lowest P, K, Ca, S and N content and the highest C content in the litterfall. Litterfall production is important in degraded areas to ensure the nutrient return to the soil. The data obtained suggest that the cultivation of a mixed of 16 native trees contribute for produce the higher annual litterfall yields, besides produces leaf litterfall of better nutritional quality in relation to P, K, Ca, Mg and S. Therefore, mixed of native trees can be a promising option for reactivation of nutrient cycling and organic matter formation in mined area of bauxite in the Brazilian Atlantic Forest.

ABSTRACT Strategies that aim to condition the soil positively impact ruminant production systems on pasture. The production of litterfall is directly responsible for improvements in the soil's chemical, physical, and biological characteristics. The objective of this study was to quantify and qualify the litterfall deposition of the Silvopastoral System with Eucalyptus (SSP) to compare with Semideciduous Seasonal Forest (FL) and Monoculture Pasture System (MN), as well as the decomposition of deciduous material. For this, 12 litterfall collectors were placed in each ecosystem, where the deposition of deciduous material was measured and stratified every 28 days for 11 months. Litterfall decomposition was evaluated using the litterbags method. The total litterfall production over the evaluated months for SSP, FL, and MN were 10.74, 7.17, and 1.01 t ha-1, respectively. The decomposition constant (k) for SSP and FL were 0.0021 and 0.0025 g g-1 day-1, while the half-life time (T0.5) was 322 and 272 days, respectively. The afforestation of pastures with eucalyptus can potentially increase organic matter production in the system and benefit the other components of SSP.

RESUMO Estratégias que objetivam condicionar o solo impactam positivamente no sistema de produção de ruminantes a pasto. A produção de serapilheira é diretamente responsável por melhorias nas características químicas, físicas e biológicas no solo. Objetivou-se neste estudo quantificar e qualificar a deposição de serapilheira do Sistema Silvipastoril com Eucalipto (SSP), a fim de compará-lo com Floresta Estacional Semidecidual (FL) e Sistema de Pastagem em Monocultivo (MN), assim como a decomposição do material decíduo. Para isso, foram instalados 12 coletores de serapilheira em cada ecossistema, onde foi mensurado e estratificado a deposição do material decíduo a cada 28 dias, por 11 meses. A decomposição da serapilheira foi avaliada através do método de litterbags. A produção total de serapilheira dos meses avaliados para SSP, FL e MN foi de 10,74, 7,17 e 1,01 t ha-1, respectivamente. A constante de decomposição (k) para SSP e FL foi de 0,0021 e 0,0025 g g-1 dia-1, enquanto o tempo de meia vida (T0,5) foi de 322 e 272 dias, respectivamente. A arborização das pastagens com eucalipto tem potencial de aumentar a produção de matéria orgânica no sistema e beneficiar os demais componentes do SSP.

Resumen Objetivo: Determinar la comunidad de miriápodos asociada a la hojarasca en dos estrategias de restauración de un área protegida de Colombia, un bosque secundario y una plantación de aliso. Alcance: El conocimiento de la biodiversidad asociada con la descomposición de la hojarasca en un ecosistema restaurado podría contribuir a evaluar la eficiencia y el éxito de la restauración. Dentro de esta biodiversidad, los miriápodos influyen en la dinámica de la materia orgánica al transformar la hojarasca reduciendo la superficie de descomposición y afectando a las comunidades de organismos asociados a la descomposición. Metodología: Diseñamos un experimento de translocación utilizando hojarasca de Alnus acuminata Kunth y Hedyosmum bonplandianum Kunth, las especies más abundantes en cada estrategia de restauración que se puso en marcha desde los años 60 en la Reserva natural Río Blanco y Quebrada Olivares, Manizales, Colombia. Medimos la riqueza y abundancia de miriápodos después de dos y cuatro meses de descomposición de la hojarasca. Principales resultados: Las clases Diplododa, Chilopoda y Symphyla colonizaron la hojarasca de A. acuminata y H. bonplandianum en ambas estrategias de restauración. La estrategia de restauración afecto la riqueza, abundancia y composición de miriápodos. La riqueza y abundancia de miriápodos fue mayor en la plantación de aliso, los milpiés mostraron la mayor abundancia. La composición de miriápodos difirió entre las especies de hojarasca. La composición vegetal de cada estrategia de restauración podría generar diferencias en la calidad de la hojarasca y, en consecuencia, en los recursos disponibles para la colonización de la comunidad de miriápodos, lo que contribuye directa e indirectamente al proceso de descomposición en las estrategias de restauración.

Abstract Objective: To determine the leaf litter myriapod community in two restoration strategies of a protective area of Colombia, a secondary forest and an Andean alder plantation. Scope: The knowledge of the biodiversity of invertebrates associated with leaf litter breakdown in restoration forests may contribute to assessing the restoration process efficiency and success. Within this forested soil biodiversity framework, myriapods influence organic matter dynamics by transforming leaf litter (or other plant-derived materials), reducing the surface of decomposition, and affecting decomposer communities and their interactions. Methodology: We designed a leaf litter translocation experiment using leaf litter of Alnus acuminata Kunth and Hedyosmum bonplandianum Kunth, the most abundant species in each restoration strategy underway from the 60s in the Reserva Natural Río Blanco y Quebrada Olivares, Manizales, Colombia. We measured the myriapod richness and abundance two and four months after beginning the leaf litter decomposition experimental trials. Main results: Classes Diplododa, Chilopoda, and Symphyla colonized the leaf litter in both restoration strategies. The restoration strategy affected myriapod richness, abundance and composition. Myriapod richness and abundance were greater in the Andean alder plantation, millipedes were the most abundance myriapods. Myriapod composition also differs among litter species. The plant composition of each restoration strategy could lead to differences in litterfall quality and, consequently, in the resources available for the colonization of the myriapod community, which contributes directly and indirectly to the decomposition process in the restoration strategies.

RESUMO A ciclagem de fósforo (P), mesmo sendo pouco estudada, é importante para o equilíbrio de macronutrientes em ecossistemas de floresta tropical úmida. Como P no solo ocorre em diferentes formas orgânicas e inorgânicas (frações), com diferentes graus de labilidade, supomos que essas frações variam temporalmente entre os diferentes tipos de solo. Além disso, hipotetizamos uma influência direta da serrapilheira no aporte de P no solo. Coletamos amostras de solo e folhas em três tipos de solo em uma floresta tropical na Amazônia central no Brasil durante cinco meses e usamos o método de fracionamento modificado de Hedley para determinar seis frações orgânicas e inorgânicas de P no solo, bem como P total, lábil e residual. As concentrações de P na serrapilheira foram determinadas pelo método de colorimetria. As frações de P inorgânico e orgânico do solo variaram entre os tipos de solo e ao longo dos meses, mas as interações entre tipo de solo e meses foram majoritariamente não significativas. Algumas frações de P inorgânicas (Pi-NaOH) atingiram o pico enquanto as frações orgânicas (Po-NaOH) caíram e vice-versa. A produção de serrapilheira e a entrada de P atingiram o pico por volta de dois meses após o mês mais chuvoso. A entrada de P da serrapilheira foi um preditor significativo de Po-NaHCO3, uma fração de P biodisponível. Futuros estudos sobre a ciclagem de P nos ecossistemas devem examinar o papel desempenhado pelas frações individuais de P no solo, à medida que circulam de forma assíncrona e diferente entre tipos de solo.

ABSTRACT Phosphorus (P) cycling is an important yet poorly studied aspect of the macronutrient balance in tropical rainforest ecosystems. As soil P occurs in different organic and inorganic forms (fractions) with varying degrees of lability, we hypothesized that these fractions will vary between soil types, and temporally within soil types. Additionally, we hypothesized a direct influence of leaf litterfall P input on soil total P and soil P fractions. We collected soil and leaf litter samples from three soil types in a central Amazonian lowland rainforest in Brazil over five months, and used a modified Hedleys fractionation method to determine six organic and inorganic soil P fractions, and also total, labile and residual P. Leaf litterfall P concentrations were determined colorimetrically. Soil inorganic and organic P fractions varied between soil types and across months, but soil type and month interactions were mostly non-significant. Some inorganic P fractions (Pi-NaOH) peaked while the organic fractions (Po-NaOH) fell and vice versa. Leaf litterfall production and leaf litterfall P input peaked around two months following the wettest month. Leaf litterfall P input was a significant predictor of Po-NaHCO3, a bioavailable P fraction. Future studies on P cycling in terrestrial ecosystems should examine the roles played by individual soil P fractions as they cycle asynchronistically and differently across soil types.

Abstract The litterfall that accumulates in the forest soil and its further decomposition play an important roll in the maintenance of productivity in different terrestrial ecosystems since its constitute the main flow of nutrients to the soil. The objective of this study was to evaluate the production of litterfall, its nutrient return thru litterfall deposition and macronutrient use efficiency. The study was conducted in Linares, Crucitas and Los Ramones, state of Nuevo León, México. Average litterfall deposition was 5 800, 5 270 and 6 596 kg ha−1 year−1 for Linares, Crucitas and Los Ramones, respectively. Total nutrient return thru litterfall followed the sequence: Linares > Crucitas > Los Ramones, with value of 135, 122 and 101 kg ha−1 year−1, respectively. Even though the return of P thru litterfall was the lowest, P nutrient use efficiency was higher with respect to Ca, Mg and K. Greatest nutrient use efficiency in terms of Ca and Mg was observed in Los Ramones, K in Crucitas and P in Linares. The results showed that there exist spatial and temporal variation in the production of litterfall, nutrient return and nutrient use efficiency between studied sites. Thus, litterfall deposition, nutrient return and nutrient use efficiency between sites depend on stand composition and richness, edaphic properties, litterfall quality, and plant phenology.

Resumen La hojarasca que se acumula sobre el piso forestal y su posterior descomposición juegan un papel importante en el mantenimiento de la productividad de los diferentes ecosistemas terrestres al constituir el principal flujo de nutrientes al suelo. El objetivo del estudio fue evaluar la producción de hojarasca y retorno de nutrientes a través de la caída de la hojarasca y la eficiencia en el uso de macro-nutrientes. El estudio se realizó en los sitios de Linares, Crucitas y Los Ramones, en el Estado de Nuevo León, México. El promedio de caída de hojarasca fue de 5 800, 5 270 a 6 596 kg ha−1 año−1 para Linares, Crucitas y Los Ramones, respectivamente. El retorno total de nutrientes siguió la secuencia: Linares > Crucitas > Los Ramones con valores de 135, 122 y 101 kg ha−1 año−1, respectivamente. A pesar de que el retorno de P en la hojarasca fue menor, la eficiencia del uso de este nutriente fue mayor que la presentada por el Ca, Mg ó K. La mayor eficiencia de uso de nutrientes en términos de Ca y Mg se observó en Los Ramones, el K en Crucitas y el P en linares. Existe variación espacial y temporal en la producción de hojarasca, retorno de nutrientes y la eficiencia en su uso entre los sitios evaluados. Por tanto, la caída de hojarasca, retorno de nutrientes y uso eficiente en estos sitios dependen de la riqueza de especies, diferencias edáficas, calidad de la hojarasca y fenología de las diferentes especies.

Abstract Introduction: It is essential to have baselines on nutrient dynamics in forests, due to disturbances that climate change may cause. Objective: To quantify the annual production of needles of Pinus hartwegii Lindl. and the proportion of nutrients in the alpine forests of Jocotitlán (JO) and Tláloc (TL) mountains, Estado de México. Materials and methods: A total of 12 circular needle litter traps (30 cm diameter) were placed at ground level, in each forest, distributed in four topographically contrasting sites. For one year, 228 leaf mass measurements and 1 140 chemical determinations were made to determine needle stoichiometry. Measurements were subjected to a longitudinal analysis of variance, by testing trends over time (P < 0.05). Results and discussion: Needle production in JO were 67 % higher (11.2 Mg∙ha-1∙year-1) than in TL (6.7 Mg∙ha-1∙year-1); needle litterfall was higher during summer (June and July, months with higher precipitation). For JO, nutrient flux was 98.0, 5.2, 8.7, 24.6, and 5.6 kg∙ha-1∙year-1 for N, P, K, Ca, and Mg, respectively; for TL it was 55.3, 3.4, 7.8, 14.4, and 4.7 kg∙ha-1∙year-1 in the same order of nutrients. Nutrient concentrations were lower from March to May. Except for K, nutrient concentrations and needle production showed quadratic and cubic seasonal trends. Mg dynamics and N:Mg and N:K ratios in TL were more positive for tree growth. Conclusions: Jocotitlán and Tláloc forests produce significant needle mass (compared to other ecosystems) with high dynamic in nutrient transfers.

Resumen Introducción: Es imprescindible tener líneas base sobre la dinámica de nutrientes en los bosques, debido a las alteraciones que el cambio climático pueda causar. Objetivo: Cuantificar la producción anual de acículas de Pinus hartwegii Lindl. y proporción de nutrientes en los bosques alpinos cerro Jocotitlán (JO) y cerro Tláloc (TL), Estado de México. Materiales y métodos: En cada bosque se colocaron 12 trampas circulares (30 cm de diámetro) para acícula, a nivel del suelo, distribuidas en cuatro sitios topográficamente contrastantes. Durante un año, se realizaron 228 mediciones de masa foliar y 1 140 determinaciones químicas para conocer la estequiometría de acículas. Las mediciones se sometieron a un análisis de varianza longitudinal, probando las tendencias en el tiempo (P < 0.05). Resultados y discusión: La producción de acículas en JO fue 67 % superior (11.2 Mg∙ha-1∙año-1) que en TL (6.7 Mg∙ha-1∙año-1); la caída fue mayor durante el verano (junio y julio, meses con mayor precipitación). En JO, el flujo de nutrientes fue 98.0, 5.2, 8.7, 24.6 y 5.6 kg∙ha-1∙año-1 para N, P, K, Ca y Mg, respectivamente; para TL fue 55.3, 3.4, 7.8, 14.4 y 4.7 kg∙ha-1∙año-1 en el mismo orden de nutrientes. Las concentraciones de nutrientes fueron más bajas de marzo a mayo. Excepto por K, las concentraciones de nutrientes y producción de acículas mostraron tendencias estacionales cuadráticas y cúbicas. La dinámica del Mg y proporciones N:Mg y N:K en TL fueron más favorables para el crecimiento arbóreo. Conclusiones: Los bosques Jocotitlán y Tláloc son muy productivos en acícula (comparados con otros ecosistemas) y dinámicos en la transferencia de nutrientes.

RESUMO A serapilheira é uma importante fonte de nutrientes para o solo e a sua decomposição pode ser influenciada pelos sistemas de uso do mesmo. Este estudo teve por objetivo avaliar a decomposição de serapilheira e seu estoque de macronutrientes em dois sistemas de cultivo do cafeeiro, sendo um sombreado (CS) e outro a pleno sol (CPS). O experimento foi realizado em uma propriedade rural do município de Cacoal, Estado de Rondônia, Brasil, em esquema fatorial 2 × 6, dois usos do solo (CS e CPS) e seis épocas de avaliação da decomposição da serapilheira (0, 30, 60, 180, 300 e 360 dias), com sete repetições. A decomposição de serapilheira foi avaliada aos 0, 30, 60, 180, 300 e 360 dias e, além disso, foi determinada a constante de decomposição (k) e o tempo de meia vida (t1/2) aos 360 dias e os teores de fósforo (P), potássio (K), cálcio (Ca), magnésio (Mg), enxofre (S) e nitrogênio (N) da serapilheira remanescente em cada tempo de decomposição. No CS há maiores perda de massa e constante de decomposição, e menor tempo de meia vida da serapilheira ao final do período. A serapilheira apresenta perda de massa em função do tempo de decomposição. Os estoques de macronutrientes N, P, K, Ca e Mg reduziram-se de forma linear durante o tempo de decomposição e ocorreu incremento no estoque de enxofre ao final do período.

ABSTRACT Litterfall is an important source of soil nutrients, but its decomposition can be affected by the crop system used. The objective of this study was to evaluate litterfall decomposition and macronutrient stocks in coffee crop systems in shaded (SHCS) environments and those in full sun (FSCS). The experiment was conducted on a rural property in Cacoal, state of Rondônia, Brazil, in a 2 × 6 factorial scheme with two crop systems (SHCS and FSCS), and six litterfall decomposition evaluation times (0, 30, 60, 180, 300, and 360 days after the litterfall was returned to the soil (DAL)), with seven replicates. The constant of decomposition (k), half-life time (t1/2) at 360 DAL, and phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), and nitrogen (N) concentrations of the remaining litterfall were determined at each evaluation time. The litterfall in the SHCS had a greater weight loss and constant of decomposition and a lower half-life time at the last evaluation, and the weight loss increased as a function of decomposition time. The litterfall stocks of macronutrients N, P, K, Ca, and Mg showed a linear decrease throughout the decomposition time, and increases in sulfur stock were found at the last evaluation.

Resumo A dinâmica de serapilheira é um dos processos fundamentais para o crescimento e manutenção de fragmentos florestais nativos, sendo considerada a principal via da ciclagem de nutrientes em florestas. Dessa forma, estudos sobre produção de serapilheira e conteúdo de nutrientes fornecem subsídios que proporcionam um melhor entendimento da dinâmica dos nutrientes. O objetivo do estudo foi identificar a sazonalidade e as condições meteorológicas que influenciam na quantifidade e no retorno de nutrientes através da serapilheira em um fragmento de Floresta Atlântica. A amostragem de serapilheira foi realizada mensalmente em 12 parcelas permanentes. Cada parcela continha 5 coletores distribuídos sistematicamente. A serapilheira foi classificada, quantificada a massa seca e nutrientes nas frações folhas e galhos + miscelânea. Foi constatado comportamento sazonal com as maiores deposições na estação do inverno. A produção média anual foi de 6,78 Mg ha-1, sendo 64,9% composta por folhas. A entrada média de nutrientes anual foi de 135.1, 115.7, 39.7, 23.5, 17.6 e 4.6 kg ha-1 para Ca, N, K, Mg, S e P respectivamente. A variável meteorológica precipitação apresentou influencia no padrão de deposição. O aumento na eficiência do uso de nutrientes no segundo ano em comparação com o primeiro indica que as plantas estrategicamente podem estar retranslocando quantidades relativas de seus nutrientes sob condições de estresse hídrico.

Abstract Litter dynamics is one of the fundamental processes for the growth and maintenance of native forest fragments, being considered the main pathway for nutrient cycling in forests. Studies on litter production and nutrient content therefore provide insights that provide a better understanding of nutrient dynamics. This study identifies the seasonality and meteorological conditions that influence the quantity and return of nutrients through litter in an Atlantic Forest fragment. Litter sampling was carried out monthly in 12 permanent plots. Each plot contained 5 littertraps distributed systematically. The litter was classified, and the dry mass and nutrients in the leaves and branches and miscellaneous fractions was quantified. Seasonal behavior was observed, with the highest depositions in the winter season. The average annual production was 6.78 Mg ha-1, with 64.9% being composed of leaves. The mean annual nutrient intake was 135.1, 115.7, 39.7, 23.5, 17.6 and 4.6 kg ha-1 for Ca, N, K, Mg, S and P, respectively. The meteorological variable precipitation influenced the deposition pattern. The increase in nutrient-use efficiency in the second year compared to the first indicates that plants strategically may be re-translocating relative amounts of their nutrients under water stress conditions.