RESUMEN
Afforestation and reforestation to meet 'Net Zero' emissions targets are considered a necessary policy by many countries. Their potential benefits are usually assessed through forest carbon and growth models. The implementation of vegetation demography gives scope to represent forest management and other size-dependent processes within land surface models (LSMs). In this paper, we evaluate the impact of including management within an LSM that represents demography, using both in-situ and reanalysis climate drivers at a mature, upland Sitka spruce plantation in Northumberland, UK. We compare historical simulations with fixed and variable CO2 concentrations, and with and without tree thinning implemented. Simulations are evaluated against the observed vegetation structure and carbon fluxes. Including thinning and the impact of increasing CO2 concentration ('CO2 fertilisation') gave more realistic estimates of stand-structure and physical characteristics. Historical CO2 fertilisation had a noticeable effect on the Gross Primary Productivity seasonal-diurnal cycle and contributed to approximately 7% higher stand biomass by 2018. The net effect of both processes resulted in a decrease of tree density and biomass, but an increase in tree height and leaf area index.
Asunto(s)
Dióxido de Carbono , Picea , Bosques , Árboles , Carbono , Fertilización , DemografíaRESUMEN
OBJECTIVE: To determine whether there is a relationship between clinically meaningful behavior problems and concurrent and future overweight in 8- to 11-year-old children. METHODS: 1998 National Longitudinal Survey of Youth interview data for 8- to 11-year-old children and their mothers were analyzed. A Behavior Problems Index score >90th percentile was considered clinically meaningful. Child overweight was defined as a body mass index (BMI) >or=95th percentile for age and sex. Multiple logistic regression was used to control for potential confounders (selected a priori): child's sex, race, use of behavior-modifying medication, history of academic retention, and hours of television per day; maternal obesity, smoking status, marital status, education, and depressive symptoms; family poverty status; and Home Observation for Measurement of the Environment-Short Form (HOME-SF) cognitive stimulation score. In an attempt to elucidate temporal sequence, a second analysis was conducted with a subsample of normal-weight children who became overweight between 1996 and 1998 while controlling for BMI z score in 1996. RESULTS: The sample included 755 mother-child pairs. Of the potential confounding variables, race, maternal obesity, academic grade retention, maternal education, poverty status, and HOME-SF cognitive stimulation score acted as joint confounders, altering the relationship between behavior problems and overweight in the multiple logistic regression model. With these covariates in the final model, behavior problems were independently associated with concurrent child overweight (adjusted odds ratio: 2.95; 95% confidence interval: 1.34-6.49). The relationship was strengthened in the subsample of previously normal-weight children, with race, maternal obesity, HOME-SF cognitive stimulation score, and 1996 BMI z score acting as confounders (adjusted odds ratio: 5.23; 95% confidence interval: 1.37-19.9). CONCLUSIONS: Clinically meaningful behavior problems in 8- to 11-year-old children were independently associated with an increased risk of concurrent overweight and becoming overweight in previously normal-weight children.