Seed Rain and Advance Regeneration in Secondary Succession in the Brazilian Amazon

Succession in the Brazilian Amazon depends on prior land-use history. Abandoned clearcuts become dominated by Cecropia trees and exhibit species replacements characteristic of natural succession in forest lightgaps. In contrast, abandoned pastures are dominated by Vismia trees that inhibit natural succession for a decade or more. Here we explore how advance regeneration and limited seed dispersal may contribute to the arrested succession in Vismia-dominated stands. Vegetation surveys showed that every Vismia stem in 3-8 year old Vismia stands originated as a re- sprout. In Cecropia stands, all tree species, including Vismia, originated mostly from seeds, after deforestation and abandonment. The 100% re-sprouts of Vismia in the abandoned pastures confirms that Vismia dominance results from re-sprouting following pasture fires. Seed rain in both Vismia and Cecropia dominated stands was limited almost exclusively to second growth species already reproducing in those stands, suggesting that the bats and birds foraging there were not bringing mature forest seeds into the second growth, but simply feeding and depositing local second growth species. As dispersal was similar in both stand types, dispersal differences cannot account for the ongoing dominance of Vismia relative to the ongoing successional transitions in Cecropia stands. Overall, advance regeneration in the form of Vismia re-sprouts is much more likely to be the driver of Vismia dominated succession than differential dispersal of mature forest seeds. In order to avoid extensive forest conversion into unproductive Vismia wastelands in the Amazon Basin, forestry permits for harvesting timber should include restrictions on subsequent anthropogenic degradation, such as conversion to pasture and prescribed burning. © Lindsay M. Wieland, Rita C. G. Mesquita, Paulo Estefano D. Bobrowiec, Tony V. Bentos, and G. Bruce Williamson

Estimation of biomass and carbon stocks: the case of the Atlantic Forest

The main objective of this paper is to present and discuss the best methods to estimate live above ground biomass in the Atlantic Forest. The methods presented and conclusions are the products of a workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest". Aboveground biomass (AGB) in tropical forests is mainly contained in trees. Tree biomass is a function of wood volume, obtained from the diameter and height, architecture and wood density (dry weight per unit volume of fresh wood). It can be quantified by the direct (destructive) or indirect method where the biomass quantification is estimated using mathematical models. The allometric model can be site specific when elaborated to a particular ecosystem or general that can be used in different sites. For the Atlantic Forest, despite the importance of it, there are only two direct measurements of tree biomass, resulting in allometric models specific for this ecosystem. To select one or other of the available models in the literature to estimate AGB it is necessary take into account what is the main question to be answered and the ease with which it is possible to measure the independent variables in the model. Models that present more accurate estimates should be preferred. However, more simple models (those with one independent variable, usually DBH) can be used when the focus is monitoring the variation in carbon storage through the time. Our observations in the Atlantic Forest suggest that pan-tropical relations proposed by Chave et al. (2005) can be confidently used to estimated tree biomass across biomes as long as tree diameter (DBH), height, and wood density are accounted for in the model. In Atlantic Forest, we recommend the quantification of biomass of lianas, bamboo, palms, tree ferns and epiphytes, which are an important component in this ecosystem. This paper is an outcome of the workshop entitled "Estimation of Biomass and Carbon Stocks: the Case of Atlantic Rain Forest", that was conducted at Ubatuba, São Paulo, Brazil, between 4 and 8 December 2006 as part of the Brazilian project "Ombrophylus Dense Forest floristic composition, structure and function at the Núcleos Picinguaba and Santa Virginia of the Serra do Mar State Park", BIOTA Gradiente

Predictors for anastomotic leak, postoperative complications, and mortality after right colectomy for cancer: Results from an international snapshot audit

Background: A right hemicolectomy is among the most commonly performed operations for colon cancer, but modern high-quality, multination data addressing the morbidity and mortality rates are lacking. Objective: This study reports the morbidity and mortality rates for right-sided colon cancer and identifies predictors for unfavorable short-term outcome after right hemicolectomy. Design: This was a snapshot observational prospective study. Setting: The study was conducted as a multicenter international study. Patients: The 2015 European Society of Coloproctology snapshot study was a prospective multicenter international series that included all patients undergoing elective or emergency right hemicolectomy or ileocecal resection over a 2-month period in early 2015. This is a subanalysis of the colon cancer cohort of patients. Main Outcome Measures: Predictors for anastomotic leak and 30-day postoperative morbidity and mortality were assessed using multivariable mixed-effect logistic regression models after variables selection with the Lasso method. Results: Of the 2515 included patients, an anastomosis was performed in 97.2% (n = 2444), handsewn in 38.5% (n = 940) and stapled in 61.5% (n = 1504) cases. The overall anastomotic leak rate was 7.4% (180/2444), 30-day morbidity was 38.0% (n = 956), and mortality was 2.6% (n = 66). Patients with anastomotic leak had a significantly increased mortality rate (10.6% vs 1.6% no-leak patients; p 65 0.001). At multivariable analysis the following variables were associated with anastomotic leak: longer duration of surgery (OR = 1.007 per min; p = 0.0037), open approach (OR = 1.9; p = 0.0037), and stapled anastomosis (OR = 1.5; p = 0.041). Limitations: This is an observational study, and therefore selection bias could be present. For this reason, a multivariable logistic regression model was performed, trying to correct possible confounding factors. Conclusions: Anastomotic leak after oncologic right hemicolectomy is a frequent complication, and it is associated with increased mortality. The key contributing surgical factors for anastomotic leak were anastomotic technique, surgical approach, and duration of surgery