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The selective logging that characterizes most timber extraction operations in the tropics leaves large patches of logging blocks (i. e., areas allocated for harvesting) intact, with no direct impacts of the harvest. For example, in the ∼10,000 ha we sampled in 48 forest management enterprises in Africa (Gabon, Republic of Congo, and the Democratic Republic of Congo), Indonesia, Suriname, and Mexico, an average of 57% (range 22-97%) of the area in logging blocks was not directly affected by timber harvests. The proportion of intact forest within logging blocks decreased very slightly with increases in harvest intensity in the accessed portion of the logging blocks (9-86 m 3 ha −1) but decreased strongly with harvest intensity in entire logging blocks (0.3-48.2 m 3 ha −1). More forest was left intact in areas farther from roads, on slopes >40%, and within 25 m of perennial streams, but the effect sizes of each of these variables was small (∼8%). It is less clear how much of the intact forest left after one harvest will remain intact through the next. Conservation benefits without reductions in timber yields will derive from better management planning so that sensitive and ecologically critical areas, such as steep slopes and riparian buffers, constitute permanent reserves of intact forest in selectively logged landscapes in the tropics.

Natural forest management in the tropics is often impeded by scarcity of advanced regeneration of commercial species. To supplement natural regeneration in a forest managed by a community in the Selva Maya of Mexico, nursery-grown Swietenia macrophylla seedlings were planted in multiple-tree felling gaps, known as bosquetes. Remnant trees are often left standing in gaps for cultural and economic reasons or due to their official protected status. We focus on these purposefully retained trees and their impacts on planted seedlings. Sampled bosquetes were 400-1800 m 2 , of which remnant trees covered a mean of 29%. Seedling height growth rates over the first 18 months after out-planting more than doubled with increased canopy openness from 0.09 m year −1 under medium cover to 0.22 m year −1 in full sun. Liana infestations and shoot tip damage were most frequent on seedlings in the open, but, contrary to our expectations, height growth rates were 0.14 m year −1 faster for liana-infested seedlings than non-infested and did not differ between damaged and undamaged seedlings. Apparently the more rapid height growth of well-illuminated seedlings more than compensated for the effects of lianas or shoot tip damage. Despite the abundance of remnant trees and their negative effects on seedling growth, enrichment planting in bosquetes has potential for community-based natural forest management in the tropics in supplementing natural regeneration of commercial species. One obvious recommendation is to leave fewer remnant trees, especially those of commercial species that are non-merchantable due to stem defects and trees retained for no apparent reason, which together constituted half of the remnant crown cover in the sampled bosquetes. Finally, given the rapid growth of lianas and understory palms in large canopy gaps, at least the most vigorous of the planted seedlings should be tended for at least two years.

Los bosques tropicales contienen aproximadamente 40% del carbono acumulado en la biomasa terrestre. Sin embargo, la pérdida y degradación de los bosques libera este carbono y contribuye con 11% de las emisiones globales totales. La degradación forestal es una fuente creciente de emisiones de carbono, que contribuye con 25% en ambientes tropicales; y la tala selectiva es una de las principales causas. El objetivo central de este estudio fue evaluar los impactos a la biomasa y las emisiones de carbono generadas por la tala selectiva en dos comunidades forestales (ejidos con uso y derecho forestal común) en el sur de la Península de Yucatán, México. Se comparó el rendimiento de emisiones de las operaciones de tala en ambos ejidos, uno de ellos certificado con manejo sostenible por el Consejo de Administración Forestal (FSC). Se registraron las especies de madera en rollo extraídas, así como el número de árboles afectados por la cosecha, y se cuantificó el tipo de daño colateral causado por la tala, el arrastre y el transporte de madera. La biomasa de la madera cosechada y la vegetación impactada fue estimada para calcular las emisiones de carbono utilizando ecuaciones alométricas. Los resultados indicaron que la tala selectiva generó 1.2 Mg m-3 y 1.5 Mg m-3 de emisiones de carbono totales en los ejidos de Caobas y 20 de Noviembre, con 5% y 12% correspondientes a daños colaterales por derribo, respectivamente. En general, hubo menores emisiones generadas y daño colateral por derribo y arrastre en Caobas, el ejido certificado por FSC. Se discutió cómo la certificación forestal, a través de prácticas de tala de impacto reducido (RIL) pueden reducir significativamente las emisiones de carbono de la tala selectiva en la región.