White Maps Research Articles

Central African biomes and forest succession stages derived from modern pollen data and plant functional types

Abstract. New detailed vegetation reconstructions are proposed in Atlantic Central Africa from a modern pollen data set derived from 199 sites (Cameroon, Gabon and Congo) including 131 new sites. In this study, the concept of plant functional classification is improved with new and more detailed plant functional types (PFTs) and new aggregations of pollen taxa. Using the biomisation method, we reconstructed (1) modern potential biomes and (2) potential succession stages of forest regeneration, a new approach in Atlantic Central African vegetation dynamics and ecosystem functioning reconstruction. When compared to local vegetation, potential biomes are correctly reconstructed (97.5% of the sites) and tropical rain forest (TRFO biome) is well identified from tropical seasonal forest (TSFO biome). When the potential biomes are superimposed on the White's vegetation map, only 76.4% of the sites are correctly reconstructed. But using botanical data, correspondence and cluster analyses, the 43 sites from Congo (Mayombe) evidence more affinities with those of central Gabon and so they can also be considered as correctly reconstructed as TRFO biome and White's map should be revised. In terms of potential succession stages of forest regeneration, the mature forest (TMFO) is well differentiated from the secondary forest (TSFE), but inside this latter group, the young and the pioneer stages are not clearly identified due probably to their low sampling representation. Moreover, linked to their progressive and mosaic character, the boundaries between two forest biomes or two forest stages are not clearly detected and need also a more intensive sampling in such transitions.

IC-P-080: Effects of aging on whole brain gray and white matter volumes and hippocampal subfields

Although memory is commonly affected in elderly healthy subjects, neuroimaging studies seeking for age related hippocampal volume loss have been controversial. One reason for this might be that the hippocampus is not homogenous but consists of histologically and functionally different subfields which might be differently affected by age. 1. To test for global age related gray and white matter volume changes. 2. To test if hippocampal age effects are global or subfield specific. 45 cognitively normal controls (aged 21–85, mean 54.5±17.4, m/f: 27/18) were studied on a 4T magnet with the following sequences: 1. Volumetric T1–weighted gradient echo MRI (MPrage) resolution 1 × 1 × 1 mm. 2. High resolution T2–weighted fast spin echo 0.4 × 0.5 × 2 mm resolution, 2, angulated perpendicular to the long axis of the hippocampus. The MPrage was segmented into gray (GM) and white maps (WM) which were used for optimized voxel–based–morphometry (VBM) in SPM2. The entorhinal cortex (ERC), subiculum, CA1, CA2 and CA3/4/dentate–compound were marked on the high resolution image on 5 consecutive slices using anatomical landmarks. The influence of age, gender and total intracranial volume on hippocampal subfields was tested using linear regression and regionally unbiased tests for age related GM/WM reductions were performed using SPM2. VBM showed age related GM reductions bilaterally in hippocampus, putamen, thalamus, cerebellum, operculum, anterior and posterior cingulate and parieto–occipital and frontal cortex while WM reductions were found in corona radiata, corpus callosum, and periventricular, temporal and frontal WM. Significant negative age effects were found for ERC (p>0.005) and CA1 (p<0.00001) and significant age and gender effects (p<0.025) for CA2 which was primarily driven by volume loss in men. Neither CA1 nor ERC volume loss was correlated with GM losses after correction for age effects. Healthy aging is associated with regionally restricted volume loss that involves cortical regions incl. ERC. In the hippocampus age effects are restricted to specific subfields, notably CA1 while others, e.g. subiculum, are less affected. This regionally distinct pattern of atrophic changes, particularly also in the hippocampus, may have diagnostic value for early detection of Alzheimer's disease.

Modern pollen-based biome reconstructions in East Africa expanded to southern Tanzania

New detailed biome reconstructions are proposed in East Africa from modern pollen data derived from 150 sites located in northern Kenya (40 sites), north-western Uganda (51 sites) and southern Tanzania (59 new sites presented as pollen diagram), which are representative of the major vegetation associations occurring in seven phytogeographical regions, mosaics or centres of endemism. We use the standard biomisation method previously published for the African continent, but we reconsider the taxa assignment to plant functional types. We include in this approach all identified taxa (408) except aquatics, ferns and exotic taxa. The method is validated by comparison with local vegetation data and we show that 124 (82.6%) sites are assigned to the correct biome and that for all the biomes under investigation, the number of correct assignments always exceeds the number of incorrect ones. When an incorrect biome reconstruction occurs, mainly toward drier biomes, this is generally linked to the local open/degraded structure of the original vegetation or to the occurrence of a mosaic of open/closed vegetation. In turn, most of the reconstructions of more humid/closed biomes than the corresponding local vegetation (8.6%) remain unexplained. A comparison of our reconstructed biomes with the main East African vegetation types of White's map indicates that 121 (80.6%) sites are assigned to the correct biomes. However, the majority of sites are incorrectly reconstructed compared to Olson and IGBP maps from satellite data, mainly due to incorrect allocation of the land cover classes compared to the potential vegetation. The application of this method to our pollen data set demonstrates that modern pollen assemblages can successfully reconstruct the main modern East African vegetation types.

Treatment of Encopresis Using Modifications to Michael White's Approach

This case study describes the efforts of one family therapy team to implement the “map for therapy” developed by Michael White to treat encopresis. Whereas the team discovered that White's map was useful in charting a general course for treatment, they also discovered the necessity of devising some novel interventions when therapy moved beyond the boundaries of the map. This article reports on implementation of the map, as well as the “detours”. The team concluded that detours will often be necessary, though the precise nature of these will depend on the idiosyncratic patterns of the particular family and family-helper systems.