Papers by Patricia Negreros-Castilo
Forest Ecology and Management, 2014
We studied succession over five years in a seasonally dry tropical forest in Quintana Roo, Mexico... more We studied succession over five years in a seasonally dry tropical forest in Quintana Roo, Mexico, following three different types of experimental disturbance (slashing and complete felling; slashing, felling and burning; and machine-clearing), each one implemented in 1996 on two 0.5 ha treatment plots. Before experimental disturbances, the floristic composition, dominance and diversity of the forest vegetation had been determined. In 1997, after treatments were applied, a second survey characterized early secondary vegetation at one year. A third survey was conducted in 2001. The 1996 vegetation composition revealed no significant differences among the six treatment plots. In 1997, floristic composition on the six treatment plots showed differences in dominance and diversity: the post-treatment vegetation on the slash/fell treatment was clearly distinct from that on the other two treatments. In 2001, differences among the plots had decreased considerably. Comparisons among seral stages revealed that one-yearold secondary vegetation differed from the pre-disturbance original vegetation, while five-year-old vegetation was similar to the original in its diversity, floristic composition and dominance. Felling alone favors species with a high resprouting capacity. The frequency of species with resprouting capacity was lower on slash/fell/burn treatments and lowest on machine-cleared plots. Results indicate that the effect of disturbance tends to decline over time and that complete clearing of small areas is effective as a silvicultural treatment to favor regeneration of valuable timber species and sustain diversity.
En este documento se explica en forma general lo que es el manejo forestal comunitario en México ... more En este documento se explica en forma general lo que es el manejo forestal comunitario en México y su importancia para el presente y futuro de la actividad forestal en nuestro país. También se incluyen datos estadísticos sobre la extensión y actividades involucradas en el manejo forestal comunitario en México. Se hace énfasis en la importancia de las comunidades nativas para la implementación de empresas forestales comunitarias (EFC). A su vez, también se analizan ejemplos de estudios que proporcionan datos que permiten constatar, y por lo tanto proponer, que el manejo forestal comunitario es una estrategia que está dando excelentes resultados para la subsistencia y autonomía de las comunidades campesinas y la conservación de los bosques bajo su manejo. Selvas 19% Bosques 21% Zonas áridas 41% Hidrófila y halófila 3% Zonas Perturbadas 16% Superficie forestal 42% Otros usos 58%
The Mexican model of community forestry is often touted as an example whereby greater community c... more The Mexican model of community forestry is often touted as an example whereby greater community control enhances both conservation and local livelihoods. We examine the conditions that have enabled and challenged sustainable forest manage-ment within community forests in Quintana Roo, a tropical state strongly influenced by the Maya culture that currently boasts 91% forest cover. Over time, community forestry has been shaped by land reforms and forest policies that institutionalised com-mon property and local governance systems, granted timber rights to communities, instigated Permanent Forest Areas for commercial management, and laid a foundation to respond to changing market opportunities (i.e. payments for environmental services, railroad ties, polewood, and future carbon credits). Significantly, 16 years of state and international support via the Forestry Pilot Plan further empowered residents and increased local capture of forest benefits. In contrast, recent neoliberal economi...
Journal of Natural Products, 2002
Figure 2. Histological characterization of leaf explant and callus. (A) Transversal section of a ... more Figure 2. Histological characterization of leaf explant and callus. (A) Transversal section of a Valeriana edulis ssp. procera seedling leaf (e ) adaxial epidermis, e 1 ) abaxial epidermis, pp ) palisade parenchyma, sp ) spongy parenchyma, bar ) 50 µm). (B) General aspect of callus after 8 weeks of culture showing clusters of small cells (scc, bar ) 250 µm). (C) Callus after 10 weeks showing meristematic (mc) and parenchymatic (pc) cells (bar ) 100 µm).
Forest Ecology and Management, 2004
Honduras or bigleaf mahogany (Swietenia macrophylla King) is the most commercially important timb... more Honduras or bigleaf mahogany (Swietenia macrophylla King) is the most commercially important timber species in the Neotropics, but it often does not regenerate successfully after harvesting. Effective methods are needed to sustain or increase mahogany yields by increasing regeneration. This study evaluates the effects of three treatments (slash, fell and burn; slash, fell and leave; and uprooting and pushing away trees using machines) used to open 0.5 ha clearings, plus a control under the forest canopy, and two sowing methods (surface-sown seed and buried seed) on the germination, establishment, survival, and early growth of mahogany. After 10 months, significantly more buried seeds yielded established seedlings (20%) than surface-sown seeds (9%), but there were no significant differences among clearing treatments. Establishment on controls averaged 18%.
Forest Ecology and Management, 2000
While carrying out an overstory removal/natural regeneration study, the number of sprouts from th... more While carrying out an overstory removal/natural regeneration study, the number of sprouts from the trees that were cut down were recorded. Seventeen species with average diameters from 9 to 36 cm were studied. The number of sprouts varied from 1 to 6, and sprout heights from 1.0 m to 5 m, 3 years after the original trees were cut. Overall, the number of sprouts and the height of the sprouts increased as the parent tree diameter increased. This information can be very useful in managing the forest for products other than timber. Firewood, medicinal plants, construction materials, edible fruits, and forages are among the different uses of the observed species. Speci®c stands might be coppiced to satisfy some of the most immediate needs of the region's inhabitants. #
Forest Ecology and Management, 2008
Seeds of mahogany and Spanish cedar were planted in gaps created by harvesting railroad ties at t... more Seeds of mahogany and Spanish cedar were planted in gaps created by harvesting railroad ties at two locations in the Yucatan Peninsula. Gaps averaged 40m2 in area. Germination after 2 months was very low (2%) for Spanish cedar and moderately low (29%) for mahogany at the one location where it was measured, probably due to predation and fungal damage. Annual
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Papers by Patricia Negreros-Castilo