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- Luyssaert, S., et al.
(författare)
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CO2 balance of boreal, temperate, and tropical forests derived from a global database
- 2007
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 13:12, s. 2509-2537
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Forskningsöversikt (refereegranskat)abstract
- Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate, and soil characteristics. This publicly available database can be used to quantify global, regional or biome-specific carbon budgets; to re-examine established relationships; to test emerging hypotheses about ecosystem functioning [e.g. a constant net ecosystem production (NEP) to gross primary production (GPP) ratio]; and as benchmarks for model evaluations. In this paper, we present the first analysis of this database. We discuss the climatic influences on GPP, net primary production (NPP) and NEP and present the CO2 balances for boreal, temperate, and tropical forest biomes based on micrometeorological, ecophysiological, and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10 degrees C. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by nonclimatic conditions such as successional stage, management, site history, and site disturbance. In all biomes, closing the CO2 balance required the introduction of substantial biome-specific closure terms. Nonclosure was taken as an indication that respiratory processes, advection, and non-CO2 carbon fluxes are not presently being adequately accounted for.
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| 3. |
- Ong, Ken K., et al.
(författare)
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Pregnancy Insulin, Glucose, and BMI Contribute to Birth Outcomes in Nondiabetic Mothers
- 2008
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 31:11, s. 2193-2197
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - We investigated the effects of normal variations in maternal glycemia on birth size and other birth outcomes. RESEARCH DESIGN AND METHODS - Women in two unselected birth cohorts, one retrospective (n = 3,158) and one prospective (n = 668), underwent an oral glucose challenge at 28 weeks of gestation. In the retrospective study, glycemia was linked to routine birth records. In the prospective study, offspring adiposity was assessed by skinfold thickness from birth to age 24 months. RESULTS - In the retrospective study, within the nondiabetic range (2.1-7.8 mmol/l), each 1 mmol/l rise in the mother's 60-min glucose level was associated with a (mean +/- SEM) 2.1 +/- 0.8% (P = 0.006) rise in absolute risk of assisted vaginal delivery, a 3.4 +/- 0.8% (P < 0.0001) rise in emergency cesarean delivery, a 3.1 +/- 0.7% (P < 0.0001) rise in elective cesarean delivery, and a 46 +/- 8 g (P < 0.0001) increase in offspring birth weight. in the prospective study, fetal macrosomia (birth weight >90th centile) was independently related to the mother's fasting glucose (odds ratio 2.61 per + 1 mmol/l [95% CI 1.15-5.93]) and prepregnancy BMI (1.10 per +1 kg/m(2) [1.04-1.18]). The mother's higher fasting glycemia (P = 0.004), lower insulin sensitivity (P = 0.01), and lower insulin secretion (P = 0.02) were independently related to greater offspring adiposity at birth. During postnatal follow-up, the correlation between the mother's glycemia and offspring adiposity disappeared by 3 months, whereas prepregnancy BMI was associated with offspring adiposity that was only apparent at 12 and 24 months (both P < 0.05). CONCLUSIONS - Prepregnancy BMI, pregnancy glycemia, insulin sensitivity, and insulin secretion all contribute to offspring adiposity and macrosomia and may be separate targets for intervention to optimize birth outcomes and later offspring health.
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