Aboveground vs. Belowground Carbon Stocks in African Tropical Lowland Rainforest: Drivers and Implications

Background: African tropical rainforests are one of the most important hotspots to look for changes in the upcoming decades when it comes to C storage and release. The focus of studying C dynamics in these systems lies traditionally on living aboveground biomass. Belowground soil organic carbon stocks have received little attention and estimates of the size, controls and distribution of soil organic carbon stocks are highly uncertain. In our study on lowland rainforest in the central Congo basin, we combine both an assessment of the aboveground C stock with an assessment of the belowground C stock and analyze the latter in terms of functional pools and controlling factors. Principal Findings Our study shows that despite similar vegetation, soil and climatic conditions, soil organic carbon stocks in an area with greater tree height (= larger aboveground carbon stock) were only half compared to an area with lower tree height (= smaller aboveground carbon stock). This suggests that substantial variability in the aboveground vs. belowground C allocation strategy and/or C turnover in two similar tropical forest systems can lead to significant differences in total soil organic C content and C fractions with important consequences for the assessment of the total C stock of the system. Conclusions/Significance: We suggest nutrient limitation, especially potassium, as the driver for aboveground versus belowground C allocation. However, other drivers such as C turnover, tree functional traits or demographic considerations cannot be excluded. We argue that large and unaccounted variability in C stocks is to be expected in African tropical rain-forests. Currently, these differences in aboveground and belowground C stocks are not adequately verified and implemented mechanistically into Earth System Models. This will, hence, introduce additional uncertainty to models and predictions of the response of C storage of the Congo basin forest to climate change and its contribution to the terrestrial C budget

Tree species effects on topsoil properties in an old tropical plantation

Forest biogeochemistry is strongly linked to the functional strategies of the tree community and the topsoil. Research has long documented that tree species affect soil properties in forests. Our current understanding on this interaction is mainly based on common garden experiments in temperate forest and needs to be extended to other ecosystems if we want to understand this interaction in natural forests worldwide. Using a 77-year-old tropical experimental plantation from central Africa, we examined the relationship between canopy and litter chemical traits and topsoil properties. By the current diversity in this site, the unique setup allowed us to extend the current knowledge from temperate and simplified systems to near-natural tropical forests, and thus bridge the gap between planted monocultures in common gardens, and correlative studies in natural systems. We linked the species-specific leaf and litter chemical traits to the topsoil cation composition, acidity, pH and soil organic matter. We found that average canopy trait values were a better predictor for the topsoil than the litter chemistry. Canopy base cation content positively affected topsoil pH and negatively affected acidity. These, in turn strongly determined the soil organic carbon contents of the topsoil, which ranged a tree-fold in the experiment

Zelfevaluatie in het secundair onderwijs

status: publishe

Handboek zelfevaluatie in het secundair onderwijs

In de literatuur vindt men vele instrumenten voor zelfevaluatie, maar zelden wordt het procesmatig karakter beklemtoond. Vandaar dat dit handboek opgevat is als een leidraad voor secundaire scholen die op een zelfstandige manier hun school willen evalueren. In dit handboek wordt zelfevaluatie benaderd vanuit een ontwikkelingsperspectief. Dit betekent dat: zelfevaluatie gegevens dient op te leveren over het huidige functioneren (sterktes en zwaktes), die de school kan brengen tot een verantwoorde planning (of visie op de toekomst) en uitvoering van verbeteringen en vernieuwingen, met het doel haar onderwijskwaliteit te optimaliseren. Hiermee wordt meteen ook het belang van procesmatig denken duidelijk. Dit handboek wil secundaire scholen op weg helpen bij hun zelfevaluatie-activiteiten door het geven van concrete tips en suggesties (in de vorm van een stappenplan). Daarenboven zal naar andere interessante bronnen bij de verschillende zelfevaluatiestappen worden verwezen. Self-evaluation is an important instrument for school-based management. School teams often search instruments for self-evaluation, but are not sufficiently interested in the process of self-evaluation, although some knowledge about the process of self-evaluation is necessary to make self-evaluations successful. This manual offers a guide for secondary schools that intent to evaluate independently the school. This book offers a step-by-step plan for secondary schools who intent to evaluate the school independently. Headmasters and teachers find in this book concrete hints and suggestions for steering the self-evaluation process.Afdeling Theoretische, cultuur- en onderwijssociologie. Centrum voor Onderwijssociologie (COS) Onderzoekseenheid Strafrecht, strafvordering en criminologie.edition: second editionstatus: publishe

Kennisgebaseerd systeem voor bloedvatensegmentatie op angiografieen

SIGLEKULeuven Campusbibliotheek Exacte Wetenschappen / UCL - Université Catholique de LouvainBEBelgiu

Long-term outcome of transjugular intrahepatic portosystemic shunt for portal hypertension in autosomal recessive polycystic kidney disease

Autosomal recessive polycystic kidney disease (ARPKD) with congenital hepatic fibrosis (CHF) causes portal hypertension and its complications. A transjugular intrahepatic portosystemic shunt (TIPSS) could serve as a symptomatic treatment for portal hypertension-related symptoms in these children.status: publishe