Estimación de biomasa aérea en plantaciones de Cedrela odorata L. y Swietenia macrophylla King

Se evaluaron las capacidades de producción de biomasa y de captura de carbono en plantaciones de Cedrela odorata y Swietenia macrophylla con 12 años en el estado de Jalisco. En campo fueron seleccionados y derribados 15 árboles de cada especie para determinar la biomasa y el carbono en el estrato aéreo; se tomaron muestras del fuste, de las ramas (brazuelo y leña) y del follaje de cada individuo para conocer su peso fresco; en el laboratorio se secaron para obtener el peso seco y con estos datos se calculó la biomasa total de cada ejemplar a partir de la relación peso seco: peso fresco. Para realizar las estimaciones se ajustaron ecuaciones de regresión tipo polinomial y potencial, el diámetro normal y la altura fueron las variables independientes. Al peso seco de cada componente del árbol se le aplicó un índice de captura de carbono de 0.4269 y con ello se obtuvo el potencial de captura de carbono atmosférico. Para C. odorata el total de biomasa promedio por espécimen fue de 34 kg, en la que se distribuye 75 % de la biomasa en el fuste, 11 % en el brazuelo, 9 % en ramas (leña) y 5 % en el follaje. Para S. macrophylla el total de biomasa promedio por espécimen fue de 26 kg, del cual 47 % se distribuye en el fuste, 19 % en el brazuelo, 23 % en ramas y 10 % en el follaje

Evaluating the Effects of Forest Cover Changes on Sediment Connectivity in a Catchment Affected by Multiple Wildfires

Abstract: Wildfire-related impacts on the hydrogeomorphic properties of river basins is scarcely studied in South American sites. Fire affects river systems by altering the forest cover, decreasing the soil infiltration capacity, modifying the sediment yields and leading to channel instability. To study the effect of the disturbance in the sediment routing, the analysis of changes in sediment connectivity, i.e. the degree of linkage between source and sink areas, has been recently used. The main aim of the present research is to adapt and apply the Index of Connectivity (IC) in a Chilean catchment affected by subsequent wildfires in 2002 and 2015. Specific objectives involve the derivation of fire severity maps of both wildfires, and the development of a weighting factor, which properly represents the impedance to sediment fluxes. We made use of satellite images and sampling plots to carry out the fire severity maps and then the Normalized Difference Vegetation Index (NDVI) for the computation of the weighting factor maps used in the connectivity analysis. The results demonstrated not only the applicability of this approach, which permitted to highlights the changes in IC patterns but even the predominant changes in forest cover as well as the preferential sources of sediment within the basi

Fire, Plant Invasions, and Erosion Events on Western Rangelands

Millions of hectares of rangeland in the western United States have been invaded by annual and woody plants that have increased the role of wildland fire. Altered fire regimes pose significant implications for runoff and erosion. In this paper we synthesize what is known about fire impacts on rangeland hydrology and erosion, and how that knowledge advances understanding of hydrologic risks associated with landscape scale plant community transitions and altered fire regimes. The increased role of wildland fire on western rangeland exposes landscapes to amplified runoff and erosion over short- and long-term windows of time and increases the risk of damage to soil and water resources, property, and human lives during extreme events. Amplified runoff and erosion postfire are a function of storm characteristics and fire-induced changes in site conditions (i.e., ground cover, soil water repellency, aggregate stability, and surface roughness) that define site susceptibility. We suggest that overall postfire hydrologic vulnerability be considered in a probabilistic framework that predicts hydrologic response for a range of potential storms and site susceptibilities and that identifies the hydrologic response magnitudes at which damage to values-at-risk are likely to occur. We identify key knowledge gaps that limit advancement of predictive technologies to address the increased role of wildland fire across rangeland landscapes. Our review of literature suggests quantifying interactions of varying rainfall intensity and key measures of site susceptibility, temporal variability in strength/influence of soil water repellency, and spatial scaling of postfire runoff and erosion remain paramount areas for future research to address hydrologic effects associated with the increased role of wildland fire on western rangelands.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202