Differences in plant cover and species composition of semiarid grassland communities of central Mexico and its effects on net ecosystem exchange

"Changes in land use across the semiarid grasslands of northern Mexico have driven a decline of plant cover and alteration of plant species composition. A number of different plant communities have resulted from these changes. Their implications, however, on the carbon (C) cycle and regional carbon balance are still poorly understood. Here, we examined the effects of plant cover loss and changes in species composition on net ecosystem CO2 exchange (NEE) and their biotic and abiotic controls. NEE was measured in five representative plant community types within a semiarid grassland by temporarily enclosing the entire aboveground ecosystem using a chamber method (i.e., geodesic dome). Sites included an oat crop (crop), a moderately grazed grassland (moderate grazing), a 28 yr-old grazing exclosure (exclosure), an overgrazed site with low perennial grass cover (overgrazed), and an overgrazed site presenting shrub encroachment (shrub encroachment). For natural vegetation, rates of standardized daytime NEE for sites with a high plant cover (exclosure and moderate grazing) were similar (P > 0.05) as compared to sites with low plant cover (overgrazed and shrub encroachment). However, yearly total nighttime NEE (carbon loss) was more than double (P < 0.05) for sites with high plant cover compared to sites with low cover, resulting to slight C sinks for the low plant cover sites, and neutral or sources for the high plant cover sites as accounted by daytime and nighttime NEE annual balance. Differences in plant cover and its associated biomass defined the sensitivity to environmental controls. Thus, daytime NEE in low plant cover sites reached light compensation points at lower photosynthetic photon flux density than those from high plant cover sites. Differences in species composition did not influence NEE rates even though there were transient or permanent changes in C3 vs. C4 functional groups. Our results allowed the detection of the large variability and contribution of different plant communities to regional C balance in patchy landscapes. Identification of the role of landscape patches in the regional C balance as either sinks or sources may provide tools allowing land use management strategies that could favor C uptake in patchy landscapes.

Almacén de carbono orgánico del suelo y abundancia ectomicorrízica bajo dos especies de coníferas en el Nevado de Toluca, México

Objective: to evaluate the effect of two forest species in soil organic carbon (SOC) stocks and ectomycorrhizal abundance (ECM) characterizing the most representative morphotypes ECM under each forest species. Design/ methodology/ approach: SOC was determined by the oxide reduction method in soil samples collected at 0-30 cm under individuals of Pinus hartwegii and Abies religiosa. Ectomycorrhizal roots were extracted of soil to quantify ECM abundance and characterize the morphotypes ECM. Results: COS under P. hartwegii (219.0 Mg ha-1) was not significantly different from that of A. religiosa (211.7 Mg ha-1), but not in the abundance of ECM, which was higher (p= 0.000) under A. religiosa (43.5%) than under P. hartwegii (26.4%). 21 total ECM morphotypes were observed, of which five were common under both forest species. Limitations on study/ implications: it is an initial study that requires subsequent molecular identification of ectomycorrhizal morphotypes. Findings/ conclusions: P. hartwegii and A. religiosa have the same capacity to storage COS under their individuals, while ECM abundance was defined by the forest species. Both forest species shared only 28% of total ECM morphotypes observed. This work contributes to knowledge as the first step for identifying the influence of the fungus-tree association on the dynamics of the COS in temperate forest soils.Objetivo: evaluar el efecto de dos especies forestales sobre los almacenes de carbono orgánico del suelo (COS) y la abundancia ectomicorrízica (ECM) caracterizando los morfotipos ECM más representativos bajo cada especie forestal. Diseño/ metodología/ aproximación: se determinó el COS mediante el método de óxido reducción en muestras de suelo colectadas a 0-30 cm de bajo individuos de Pinus hartwegii y Abies religiosa. Se extrajeron las raíces ectomicorrizadas para cuantificar la abundancia ECM y realizar identificación de morfotipos ECM. Resultados: El COS bajo P. hartwegii (219.0 Mg ha-1) no fue significativamente diferente al de A. religiosa (211.7 Mg ha-1), pero no así en la abundancia ECM, que fue mayor (p=0.000) bajo A. religiosa (43.5 %) que bajo P. hartwegii (26.4 %). Se observaron 21 morfotipos ECM en total, de los cuales cinco fueron comunes en ambas especies arbóreas. Limitaciones/ implicaciones: se trata de un estudio preliminar que requiere la identificación molecular a posteriori de los morfotipos ECM. Hallazgos/ conclusiones: P. hartwegii y A. religiosa tienen la misma capacidad para almacenar COS bajo sus individuos, mientras la abundancia ECM estuvo definida por la especie forestal. Ambas especies forestales compartieron sólo el 28% del total de morfotipos ECM observados. Este trabajo contribuye al conocimiento como primer paso para identificar la influencia de la asociación hongo-árbol sobre la dinámica del COS en bosques templados

Effects of the combining ability on mirador chili (Capsicum annuum L.) populations native to Veracruz, Mexico

Objective: Evaluate the effects of general and specific combining ability in agronomic characters of native populations of mirador pepper and identify genotypes with potential for the genetic improvement of the crop. Design/methodology/approach: The general and specific combining ability for agronomic and yield characteristics was calculated in five mirador pepper populations, using method 2, Griffing model I, which includes the parents and direct crosses. Results: The P1, P4 and P3 genotypes presented the highest values, positive and with a significant difference for general combining ability, while for specific combining ability the highest value was observed for the P1xP5 and P4xP5 crosses. Limitations on study/implications: It was not possible to establish diverse evaluation environments and genomic selection studies using molecular markers. Findings/conclusions: Information was generated on the yield potential of five mirador pepper populations, of importance for a genetic improvement program and for the selection of the improvement method. Keywords: plant breeding, native populations, yield.Objective: To evaluate the effects of the general and specific combining abilities on the agronomic traits of the native populations of mirador chili and to identify potential genotypes for the genetic improvement of this crop. Design/Methodology/Approach: The general and specific combining abilities were calculated to determine the agronomic traits and yield of five mirador chili populations, using Griffing’s method 2, model I, which includes parental lines and direct crosses. Results: The P1, P4, and P3 genotypes recorded the highest and positive values. They also recorded a significative difference regarding the general combining ability. Meanwhile, the P1×P5 and P4×P5 crosses recorded the highest specific combining ability values. Study Limitations/Implications: We were not able to establish diverse evaluation environments and genomic selection studies using molecular markers. Findings/Conclusions: Information about the yield potential of five mirador chili was generated. These results are important for the development of a genetic improvement program and for the selection of the method that will be used

Sleep matters: Neurodegeneration spectrum heterogeneity, combustion and friction ultrafine particles, industrial nanoparticle pollution, and sleep disorders—Denial is not an option

Sustained exposures to ubiquitous outdoor/indoor fine particulate matter (PM2.5), including combustion and friction ultrafine PM (UFPM) and industrial nanoparticles (NPs) starting in utero, are linked to early pediatric and young adulthood aberrant neural protein accumulation, including hyperphosphorylated tau (p-tau), beta-amyloid (Aβ1 − 42), α-synuclein (α syn) and TAR DNA-binding protein 43 (TDP-43), hallmarks of Alzheimer's (AD), Parkinson's disease (PD), frontotemporal lobar degeneration (FTLD), and amyotrophic lateral sclerosis (ALS). UFPM from anthropogenic and natural sources and NPs enter the brain through the nasal/olfactory pathway, lung, gastrointestinal (GI) tract, skin, and placental barriers. On a global scale, the most important sources of outdoor UFPM are motor traffic emissions. This study focuses on the neuropathology heterogeneity and overlap of AD, PD, FTLD, and ALS in older adults, their similarities with the neuropathology of young, highly exposed urbanites, and their strong link with sleep disorders. Critical information includes how this UFPM and NPs cross all biological barriers, interact with brain soluble proteins and key organelles, and result in the oxidative, endoplasmic reticulum, and mitochondrial stress, neuroinflammation, DNA damage, protein aggregation and misfolding, and faulty complex protein quality control. The brain toxicity of UFPM and NPs makes them powerful candidates for early development and progression of fatal common neurodegenerative diseases, all having sleep disturbances. A detailed residential history, proximity to high-traffic roads, occupational histories, exposures to high-emission sources (i.e., factories, burning pits, forest fires, and airports), indoor PM sources (tobacco, wood burning in winter, cooking fumes, and microplastics in house dust), and consumption of industrial NPs, along with neurocognitive and neuropsychiatric histories, are critical. Environmental pollution is a ubiquitous, early, and cumulative risk factor for neurodegeneration and sleep disorders. Prevention of deadly neurological diseases associated with air pollution should be a public health priority

Yield and forage quality in maize (Zea mays L.) inbred lines

Objective: Analyze the genetic diversity of 100 maize inbred lines with respect to agronomic characters, forage yield and fiber content, in addition, identify genotypes with potential for the plant breeding of said traits.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Design/methodology/approach: 100 maize inbred lines were evaluated in two environments, in a 10 x 10 complete block experimental design, with two repetitions. Data of days to male flowering, days to female flowering, cob height, plant height, stem diameter, green forage yield, neutral detergent fiber and acid detergent fiber were recorded. Results: Significant differences were observed for the environmental sources of variation and genotypes for all the characters evaluated. The first four components explain 81% of the total variation observed and the first two 66% of the variation. The variables with the highest absolute value and that determine in a relevant way the dispersion of the genotypes, as well as the formation of groups were, for component one: plant height, forage yield, and acid detergent fiber and for component two days a female flowering and days to male flowering; the above, allowed the dispersion of the genotypes in four groups. Limitations on study/implications: It was not possible to conduct genetic diversity studies using molecular markers. Findings/conclusions: The grouping pattern of inbred lines shows the genetic diversity present; this can be an important tool in genetic improvement programs to obtain hybrids with specific characteristics.Objective: To analyze the genetic diversity (agronomic attributes, forage yield, and fiber content) of 100 maize inbred lines and to identify genotypes with potential for the breeding of plants with the said traits. Design/methodology/approach: One-hundred maize inbred lines were evaluated in two environments, in a 10 x 10 complete block experimental design, with two repetitions. Days to male flowering, days to female flowering, ear height, plant height, stem diameter, green forage yield, neutral detergent fiber, and acid detergent fiber data were recorded. Results: Significant differences were observed in the environmental sources of variation and genotypes for all the traits evaluated. The first four components account for 81% of the total variation observed and the first two account for 66% of the variation. The variables which have the highest absolute value and which strongly influence the dispersion of the genotypes, as well as the formation of groups, were: plant height, forage yield, and acid detergent fiber (component one) and days to female flowering and days to male flowering (component two). Consequently, the genotypes were dispersed in four groups. Study limitations/implications: It was not possible to conduct genetic diversity studies using molecular markers. Findings/conclusions: The grouping pattern of inbred lines shows the genetic diversity present; this can be an important tool in genetic improvement programs aimed at obtaining hybrids with specific characteristics

Absorción foliar de nitrógeno por depósito húmedo simulado en follaje nuevo de abies religiosa (h. b. k.) schl. et cham

La absorción foliar directa de nitrógeno (N) es un proceso importante en algunos ecosistemas forestales. El objetivo del presente trabajo fue cuantificar, en invernadero, la cantidad de nitrato y amonio (NH4 +) fijado en la biomasa de follaje nuevo de Abies religiosa. Se usó un diseño experimental completamente al azar con un arreglo factorial 23 de tratamientos. Se utilizaron compuestos de 15 N para seguir la ruta del N absorbido. Hubo diferencias significativas en la absorción foliar sólo para la forma y dosis de N. El valor medio de N recuperado (%Nr) fue 5.3% para NH4 4.7 % para NO3 -----; para la dosis alta fue 6.8% y para la baja 3.1%. El %Nr en follaje nuevo no fue diferente (p>0.05) entre las condiciones de escurrimiento; sin embargo, cuando el Nr se expresó en masa neta, las diferencias por escurrimiento fueron significativas , con la mayor absorción de N cuando se permitió el escurrimiento al sustrato. De acuerdo con estos resultados hay un alto potencial de absorción foliar de N en Abies religiosa

Distribución de biomasa aérea en un bosque de Pinus patula bajo gestión forestal en Zacualtipán, Hidalgo, México

La acumulación y distribución de biomasa hacia los componentes estructurales de los árboles es determinante en bosques manejados, tanto en términos de productividad maderable como en la reactivación de diversos procesos ecosistémicos. En el presente estudio se analizó el patrón de acumulación de biomasa aérea total (BAT) y su asignación hacia fuste, ramas, corteza y follaje en una cronosecuencia de un bosque de Pinus patula bajo aprovechamiento forestal en Zacualtipán, Hidalgo. Mediante el uso de ecuaciones alométricas se estimó la BAT y por componente estructural de los árboles en rodales con diferentes años después de la cosecha, en diferentes años de remedición (años 2005, 2008 y 2012). Se encontró que la BAT aumentó con el tiempo después de la cosecha, con diferencias estadísticas significativas (p ramas> corteza> follaje. Esta asignación de BA fue favorecida hacia fuste como un producto maderable comercial, objetivo principal de estos bosques bajo producción. El patrón de asignación de BA entre los componentes estructurales de los árboles puede ser incorporado como base para el diseño de prácticas silvicuturales en los programas de manejo forestal y contribuir en la evaluación de la sustentabilidad de los bosques. Además, puede clarificar el papel de los bosques regenerados después de los aprovechamientos en la fijación y almacenamiento de bióxido de carbono atmosférico

Distribución de biomasa aérea en un bosque de Pinus patula bajo gestión forestal en Zacualtipán, Hidalgo, México

Abstract: Aboveground biomass accumulation and allocation to the structural components of trees is crucial in managed forests, both in terms of timber productivity and the reactivation of different ecosystem processes. In this study, we analyzed the pattern of accumulation of aboveground total biomass and its allocation among stems, branches, bark and foliage in a chronosequence of managed Pinus patula forests in Zacualtipán, Hidalgo. Total aboveground biomass (TAB) and its allocation to structural components were estimated by using allometric equations in stands with different numbers of years since harvest, in different years of measurement (2005, 2008 and 2012). We found that the TAB increased with time since harvest, with highly significant differences (p branches> bark> foliage. Allocation favored the stem as a commercial timber product, which is the main objective of these managed forests. The pattern of aboveground biomass allocation among the structural components of the trees reflects the fact that forest management in temperate forests operates as an important alternative for the recovery of degraded forests. Because of climate change, it can also represent an appropriate strategy for carbon sequestration and mitigation of carbon dioxide emissions.Resumen: La acumulación y distribución de biomasa hacia los componentes estructurales de los árboles es determinante en bosques manejados, tanto en términos de productividad maderable como en la reactivación de diversos procesos ecosistémicos. En el presente estudio se analizó el patrón de acumulación de biomasa aérea total (BAT) y su asignación hacia fuste, ramas, corteza y follaje en una cronosecuencia de un bosque de Pinus patula bajo aprovechamiento forestal en Zacualtipán, Hidalgo. Mediante el uso de ecuaciones alométricas se estimó la BAT y por componente estructural de los árboles en rodales con diferentes años después de la cosecha, en diferentes años de remedición (años 2005, 2008 y 2012). Se encontró que la BAT aumentó con el tiempo después de la cosecha, con diferencias estadísticas significativas (p ramas> corteza> follaje. Esta asignación de BA fue favorecida hacia fuste como un producto maderable comercial, objetivo principal de estos bosques bajo producción. El patrón de asignación de BA entre los componentes estructurales de los árboles puede ser incorporado como base para el diseño de prácticas silvicuturales en los programas de manejo forestal y contribuir en la evaluación de la sustentabilidad de los bosques. Además, puede clarificar el papel de los bosques regenerados después de los aprovechamientos en la fijación y almacenamiento de bióxido de carbono atmosférico

Distribución de biomasa aérea en un bosque de Pinus patula bajo gestión forestal en Zacualtipán, Hidalgo, México

La acumulación y distribución de biomasa hacia los componentes estructurales de los árboles es determinante en bosques manejados, tanto en términos de productividad maderable como en la reactivación de diversos procesos ecosistémicos. En el presente estudio se analizó el patrón de acumulación de biomasa aérea total (BAT) y su asignación hacia fuste, ramas, corteza y follaje en una cronosecuencia de un bosque de Pinus patula bajo aprovechamiento forestal en Zacualtipán, Hidalgo. Mediante el uso de ecuaciones alométricas se estimó la BAT y por componente estructural de los árboles en rodales con diferentes años después de la cosecha, en diferentes años de remedición (años 2005, 2008 y 2012). Se encontró que la BAT aumentó con el tiempo después de la cosecha, con diferencias estadísticas significativas (p ramas> corteza> follaje. Esta asignación de BA fue favorecida hacia fuste como un producto maderable comercial, objetivo principal de estos bosques bajo producción. El patrón de asignación de BA entre los componentes estructurales de los árboles puede ser incorporado como base para el diseño de prácticas silvicuturales en los programas de manejo forestal y contribuir en la evaluación de la sustentabilidad de los bosques. Además, puede clarificar el papel de los bosques regenerados después de los aprovechamientos en la fijación y almacenamiento de bióxido de carbono atmosférico

Improvement of Ruminal Neutral Detergent Fiber Degradability by Obtaining and Using Exogenous Fibrolytic Enzymes from White-Rot Fungi

The present review examines the factors and variables that should be considered to obtain, design, and evaluate EFEs that might enhance ruminal NDF degradability. Different combinations of words were introduced in Google Scholar, then scientific articles were examined and included if the reported factors and variables addressed the objective of this review. One-hundred-and-sixteen articles were included. The fungal strains and culture media used to grow white-rot fungi induced the production of specific isoforms of cellulases and xylanases; therefore, EFE products for ruminant feed applications should be obtained in cultures that include the high-fibrous forages used in the diets of those animals. Additionally, the temperature, pH, osmolarity conditions, and EFE synergisms and interactions with ruminal microbiota and endogenous fibrolytic enzymes should be considered. More consistent results have been observed in studies that correlate the cellulase-to-xylanase ratio with ruminant productive behavior. EFE protection (immobilization) allows researchers to obtain enzymatic products that may act under ruminal pH and temperature conditions. It is possible to generate multi-enzyme cocktails that act at different times, re-associate enzymes, and simulate natural protective structures such as cellulosomes. Some EFEs could consistently improve ruminal NDF degradability if we consider fungal cultures and ruminal environmental conditions variables, and include biotechnological tools that might be useful to design novel enzymatic products