At least one climate model predicts severe reductions of rainfall over Amazonia during this century. Long-term throughfall exclusion (TFE) experiments represent the best available means to ...investigate the resilience of the Amazon rainforest to such droughts. Results are presented from a 7 yr TFE study at Caxiuanã National Forest, eastern Amazonia. We focus on the impacts of the drought on tree mortality, wood production and above-ground biomass. Tree mortality in the TFE plot over the experimental period was 2.5% yr⁻¹ compared with 1.25% yr⁻¹ in a nearby control plot experiencing normal rainfall. Differences in stem mortality between plots were greatest in the largest (> 40 cm diameter at breast height (dbh)) size class (4.1 % yr⁻¹ in the TFE and 1.4% yr⁻¹ in the control). Wood production in the TFE plot was 30% lower than in the control plot. Together, these changes resulted in a loss of 37.8 ± 2.0 Mg carbon (C) ha⁻¹ in the TFE plot (2002-2008), compared with no change in the control. These results are remarkably consistent with those from another TFE (at Tapajós National Forest), suggesting that eastern Amazonian forests may respond to prolonged drought in a predictable manner.
Litter provides comfort to animals while improving productive performance and carcass quality. The objective of this study evaluated broiler performance, incidence of contact dermatitis, and quality ...of poultry litter of wood shavings and/or sugarcane bagasse (SB) after five consecutive flocks. Two thousand birds were raised in five consecutive flocks composed of 400 chicks each. The experiment was set in a completely randomized design with five treatments and four repetitions. The treatments consisted of substituting wood shavings with different levels of SB (0, 25, 50, 75, and 100%). Litter density, pH, dry matter content, total nitrogen, and phosphorus did not vary between treatments. However, substituting wood shavings with SB increased moisture retention capacity of the litter and ammonia production. Neither carcass lesions nor productive performance, with the exception of weight gain and feed conversion ratio in the fifth flock, differed between treatments. Substituting 75% of wood shavings with SB maintained litter quality and improved poultry performance.
PDF
