ABSTRACT
Allometric equations allow aboveground tree biomass and carbon stock to be estimated from tree size. The allometric scaling theory suggests the existence of a universal power-law relationship between tree biomass and tree diameter with a fixed scaling exponent close to 8/3. In addition, generic empirical models, like Chave's or Brown's models, have been proposed for tropical forests in America and Asia. These generic models have been used to estimate forest biomass and carbon worldwide. However, tree allometry depends on environmental and genetic factors that vary from region to region. Consequently, theoretical models that include too few ecological explicative variables or empirical generic models that have been calibrated at particular sites are unlikely to yield accurate tree biomass estimates at other sites. In this study, we based our analysis on a destructive sample of 481 trees in Madagascar spiny dry and moist forests characterized by a high rate of endemism (> 95%). We show that, among the available generic allometric models, Chave's model including diameter, height, and wood specific gravity as explicative variables for a particular forest type (dry, moist, or wet tropical forest) was the only one that gave accurate tree biomass estimates for Madagascar (R2 > 83%, bias < 6%), with estimates comparable to those obtained with regional allometric models. When biomass allometric models are not available for a given forest site, this result shows that a simple height-diameter allometry is needed to accurately estimate biomass and carbon stock from plot inventories.
Subject(s)
Biomass , Carbon/chemistry , Environmental Monitoring/methods , Models, Biological , Trees/physiology , Tropical Climate , Madagascar , Specific Gravity , Water , Wood/chemistryABSTRACT
BACKGROUND: A few studies report malnutrition in hospitalized patients. MATERIAL AND METHODS: This one-day cross-sectional survey performed in January 1999 assessed nutritional status and protein-energy intake in a pediatric population hospitalized in medicine or surgery units. Every child older than six months, hospitalized for more than 48 h and free of nutritional support (parenteral, enteral, or special regimens for metabolic diseases) was included. RESULTS: Fifty-eight children among the 183 present the day of the study met the inclusion criteria and were included in the statistical analysis. They were hospitalized in medicine (48%), psychiatry (31%) and surgery (21%). The body mass index (BMI) was below -2 standard deviations (DS) in 21% of them. Excluding patients with anorexia nervosa, BMI was < -2 SD, > +2 SD, or in between these limits in respectively 12, 14 and 74%. Energy intake measured at the hospital was below 75% of the recommended dietary allowances in two-thirds of the children whether malnourished or not. Fifty percent of the malnourished children had been referred to a dietician the day of the study. CONCLUSIONS: Malnutrition is frequent in a population of hospitalized children. Energy intake and referral to a dietician are insufficient.
