André Thibaut

Site index curves and autecology of ash, sycamore and cherry in Wallonia (Southern Belgium)

Summary The work described in this article forms part of an exploratory study 1 whose aim was to determine the main aspects of the autecology of ash (Fraxinus excelsior L.), sycamore (Acer pseudoplatanus L.) and cherry (Prunus avium L.) in Wallonia (Southern Belgium). The potential productivity of these species was studied using the site index approach (the height a crop achieves at a given age) which is the most widely accepted means for estimating site quality. As a first step, a set of site index curves were constructed from stem analysis and semi-permanent plots data using the Johnson (1935) and Schumacher (1939) model for ash and the Duplat and Tran-Ha (1986) model II for sycamore and cherry. For ash, dominant height achieved at age 50 is related to various soil-site characters (through adequate multiple regression analysis) in order to make the predictions of site quality applicable to both forested and non-forested land. Furthermore the sites expressed through soil attributes are classified in ‘a site catalogue’ for each species according to their productivity level.

Positive-Contrast Ventriculography

Iodoventriculography, the radiological examination of the ventricular system by means of an opaque contrast medium, was introduced by Balado [23–25] in 1928. In 1964 Portera [354–356] suggested employing iodate emulsions which diffuse through the CSF. With this technique (which the author named panventriculography) all parts of the ventricular system can be visualized simultaneously.

Positive Contrast Cisternography of the Posterior Fossa

As far as we know, the first attempt to study the posterior fossa radiologically was made by Brown and Aye [63] in 1955. However, these authors only succeeded in showing the “negative” image of the vertebral artery but did not obtain any further information on the anatomy and pathology of the cerebello-pontine angle.

Radioisotope Examination of the CSF Pathways

As far as we are aware, the first attempt to study the spinal subarachnoid space by radioactive isotopes was made in 1953 by Bauer and Yuhl [28], who injected by the lumbar route 131I to verify whether the spinal arachnoid spaces were pervious or not.