Ponencias, comunicaciones, resúmenes de congresos

URI permanente para esta colecciónhttps://repositorio.inia.gob.pe/handle/20.500.12955/10

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Carbon dynamics in slash and burn systems and land use alternatives: findings of the alternative to slash and burn programme
(Instituto Nacional de Innovación Agraria - INIA, 1998) Woomer, P. L.; Palm, C. A.; Alegre Horihuela, Julio; Castillo Cobella, Carlos; Cordeiro, D. G.; Hairiah, K.; Kotto Same, J.; Moukam, A; Ricse Tembladera, Auberto
Conversion of natural ecosystems to agriculture, particularly through tropical deforestation, is a major source of greenhouse gas emission into the atmosphere. Too often, fallow intervals become increasingly shortened or eliminated as land use intensifies in recently cleared forests resulting in a large net loss of total system carbon. Total system carbon (TSC) was calculated for 116 sites in the humid forest zones of S.E. Asia (Indonesia), Africa (Cameroon) and the Amazon (Brazil and Peru) based on estimates of tree, understorey and root biomass, surface necromass and soil organic carbon. The land use categories examined were original forests (10), managed and logged-over forests (9), recently burned croplands (IS), bush and young improved fallows (17), tree fallows (8), secondary' forests (8), pastures (9), /mpercra spp. grasslands (8). immature experimental agroforests (10) and mature agroforests and tree plantations (19). The land uses were arranged into chronosequences based upon land use transition and duration. TSC in a 20 year ’’traditional” slash-and-bum sequence were (t ha l): original forest (305) to burned cropland (52) to bush fallow (85) to tree fallow (136) to secondary forest (219). Logging reduced forest system carbon by 124 t ha '. Ten year-old pastures and 13 year-old Imperóla spp. grasslands contained less TSC than croplands (-4 and -5 t C ha , resDectively). Recently established agmforesrry systems contain more TSC than did croplands (+11 t C ha1). Mature agroforests (130 t C ha1) contained significantly greater TSC than croplands, pastures and grasslands (p<0.00l) but significantly less than secondary forests of similar age (p < 0.001). Soil organic carbon (SOC) represented 25% of the TSC stocks in original forests and 84%, 82% and 91% in croplands, pastures and Imperóla spp. grasslands, respectively. Aboveground C accounted for a majority of the loss from forests converted to croplands (82%) but the SOC content of croplands was also reduced by 17% to 35 t C ha1 (approximately 0-20 cm). Carbon sequestration rates were calculated for three land use patterns derivéd from croplands. Natural fellows re-accumulated 7.9 t C ha * yr‘ following land abandonment (r = 0.92). Agroforestry systems, established at the time of initial land clearing, sequestered 3.3 t C ha1 yr1 (r = 0.70) and pastures/grasslands tended to lose C at a slow rate (600 kg ha1 yr'1, n.s.). Land use systems where trees are planted and managed have greater potential to sequester C than field crops or pastures, but at sequestration rates less than those of natural succession.
Defectos congénitos y hereditarios visibles en alpacas de dos zonas representativas de la región Puno
(Asociación Latinoamericana de Producción Animal, 2007-10-30) Huanca Mamani, Teodosio; Apaza Castillo, Nolberto; Sapana Valdivia, Rómulo
El estudio se realizó en dos ámbitos agroecológicos de la crianza de alpacas, geopolíticamente ubicados en fronteras internacionales de la región Puno, durante el año 2006, mediante caracterización individual de animales in situ, con el objetivo de determinar la presencia de defectos congénitos y consanguíneos en alpacas, los resultados fueron analizadas, mediante estadística descriptiva, DCA y prueba de “t”, en las comparaciones; los resultados fueron: 9 684 alpacas caracterizadas, entre machos y hembras; de los cuales el 60,4% fue de puna húmeda y 39,6% de puna seca, los defectos congénitos y hereditarios en puna húmeda fueron: 32,28% en hembras y 45,74% en machos, mientras que en puna seca: 32,8% y 38,74% en hembras y machos respectivamente, siendo significativo a favor de los machos de puna húmeda (P=0.05), que estaría condicionado por la constante migración de los mejores ejemplares. Los defectos que se presentaron en ambos ámbitos, no fueron significativos (P=0.05); sin embargo los defectos vellón manchado 12,96%, fibra gruesa 11,94%, pelos gruesos o brish 2,98%, prognatismo 2,33% y ojos zarcos 2,28% fueron los más importantes, continuando con la falta de conformación, presencia de canas, hipoplasia testicular, microtia, criptorquideos, ectopia testicular y enanismo.

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Examinando Ponencias, comunicaciones, resúmenes de congresos por Materia "Agroecología"