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Contrasting spatial patterns in active-fire and fire-suppressed mediterranean climate old-growth mixed conifer forests

Danny L. Fry  (2014, [Artículo])

In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha-1, and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥56%) in large patches (≥10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

article, climate, controlled study, ecosystem fire history, forest structure, geographic distribution, geographic mapping, land use, mathematical computing, mathematical model, Mexico, spatial analysis, taiga, United States, comparative study, conife CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Estimación hídrica teórica de plantas en zonas urbanas: estudio de caso "Vertical Farm"

Jorge Flores Velazquez JUAN MANUEL ANGELES HERNANDEZ (2018, [Ítem publicado en memoria de congreso])

La gestión integrada de recursos hídricos es un proceso que promueve la gestión y el desarrollo coordinados del agua, el suelo” y demás recursos para potenciar su uso “sin comprometer la sostenibilidad de los ecosistemas vitales”. En la zona metropolitana de la ciudad de México habitan más de 22 millones de una población apostada en aproximadamente 8000 km2, lo que implica una densidad de habitantes de las más altas del mundo que ha ido absorbiendo la zona rural por la urbana. Frente a ello, se han puesto en marcha tecnologías disruptivas con el fin de atender la transformación del sector. Pero, además, implica gestión del recurso mediante tratamiento de aguas residuales, reciclaje del agua, cosecha de lluvia y de gestión de la demanda. En este trabajo se expone la viabilidad en la implantación de estas tecnologías, sus ventajas y requerimientos desde el punto de vista hídrico.

Agricultura urbana Riego Áreas verdes Gestión integrada de recursos hídricos INGENIERÍA Y TECNOLOGÍA

Islas de calor urbanas: un fenómeno poco estudiado en México

ULISES MANZANILLA QUIÑONES (2022, [Artículo])

El presente ensayo pretende dar a conocer la alternativa del uso de técnicas de percepción remota en la identificación de las islas de calor urbanas (ICU), fenómeno urbano mundial que ha sido poco estudiado en México. Mediante el procesamiento y análisis de imágenes satelitales es factible y confiable determinar áreas con una temperatura superficial mayor, es decir, calcular la diferencia en temperatura registrada entre un área urbana y un área rural. A través del uso de estas técnicas es posible diseñar planes para la mitigación y control de las ICU de las grandes ciudades de México.

AREAS URBANAS AUMENTO EN TEMPERATURA ESTRES TERMICO GEOGRAFIA URBANA METROPOLIS BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ECOLOGÍA VEGETAL ECOLOGÍA VEGETAL

Mulch application as the overarching factor explaining increase in soil organic carbon stocks under conservation agriculture in two 8-year-old experiments in Zimbabwe

Regis Chikowo Christian Thierfelder Marc Corbeels (2024, [Artículo])

Conservation agriculture (CA), combining reduced or no tillage, permanent soil cover, and improved rotations, is often promoted as a climate-smart practice. However, our understanding of the impact of CA and its respective three principles on top- and subsoil organic carbon stocks in the low-input cropping systems of sub-Saharan Africa is rather limited. This study was conducted at two long-term experimental sites established in Zimbabwe in 2013. The soil types were abruptic Lixisols at Domboshava Training Centre (DTC) and xanthic Ferralsol at the University of Zimbabwe farm (UZF). The following six treatments, which were replicated four times, were investigated: conventional tillage (CT), conventional tillage with rotation (CTR), no tillage (NT), no tillage with mulch (NTM), no tillage with rotation (NTR), and no tillage with mulch and rotation (NTMR). Maize (Zea mays L.) was the main crop, and treatments with rotation included cowpea (Vigna unguiculata L. Walp.). The soil organic carbon (SOC) concentration and soil bulk density were determined for samples taken from depths of 0–5, 5–10, 10–15, 15–20, 20–30, 30–40, 40–50, 50–75 and 75–100 cm. Cumulative organic inputs to the soil were also estimated for all treatments. SOC stocks at equivalent soil mass were significantly (p<0.05) higher in the NTM, NTR and NTMR treatments compared with the NT and CT treatments in the top 5 cm and top 10 cm layers at UZF, while SOC stocks were only significantly higher in the NTM and NTMR treatments compared with the NT and CT treatments in the top 5 cm at DTC. NT alone had a slightly negative impact on the top SOC stocks. Cumulative SOC stocks were not significantly different between treatments when considering the whole 100 cm soil profile. Our results show the overarching role of crop residue mulching in CA cropping systems with respect to enhancing SOC stocks but also that this effect is limited to the topsoil. The highest cumulative organic carbon inputs to the soil were observed in NTM treatments at the two sites, and this could probably explain the positive effect on SOC stocks. Moreover, our results show that the combination of at least two CA principles including mulch is required to increase SOC stocks in these low-nitrogen-input cropping systems.

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SOIL ORGANIC CARBON CONSERVATION AGRICULTURE EXPERIMENTATION CROP MANAGEMENT