Linking Land‐Use Scenarios,Remote Sensing and Monitoring to Project Impact of Management Decisions

Large‐scale modifications of natural ecosystems lead to mosaics of natural, semi‐natural and intensively used habitats. To improve communication in conservation planning, managers and other stakeholders need spatially explicit projections at the landscape scale of future biodiversity under different land‐use scenarios. For that purpose, we visualized the potential effect of five forest management scenarios on the avifauna of Kakamega Forest, western Kenya using different measures of bird diversity and GIS data. Future projections of bird diversity combined: (1) remotely sensed data on the spatial distribution of different forest management types; (2) field‐based data on the biodiversity of birds in the different management types; and (3) forest management scenarios that took into account possible views of various stakeholder groups. Management scenarios based on the species richness of forest specialists were very informative, because they reflected differences in the proportions of near‐natural forest types among the five scenarios. Projections based on community composition were even more meaningful, as they mirrored not only the proportions of near‐natural forest types, but also their perimeter to area ratios. This highlights that it is important to differentiate effects of the total area of available habitat and the degree of habitat fragmentation, both for species richness and community composition. Furthermore, our study shows that an approach that combines land‐use scenarios, remote sensing and field data on biodiversity can be used to visualize future biodiversity. As such, visualizations of alternative scenarios are valuable for successful communication about conservation planning considering different groups of stakeholders in species‐rich tropical forests.     

Additive effects of exotic plant abundance and land-use intensity on plant–pollinator interactions

The continuing spread of exotic plants and increasing human land-use are two major drivers of global change threatening ecosystems, species and their interactions. Separate effects of these two drivers on plant–pollinator interactions have been thoroughly studied, but we still lack an understanding of combined and potential interactive effects. In a subtropical South African landscape, we studied 17 plant–pollinator networks along two gradients of relative abundance of exotics and land-use intensity. In general, pollinator visitation rates were lower on exotic plants than on native ones. Surprisingly, while visitation rates on native plants increased with relative abundance of exotics and land-use intensity, pollinator visitation on exotic plants decreased along the same gradients. There was a decrease in the specialization of plants on pollinators and vice versa with both drivers, regardless of plant origin. Decreases in pollinator specialization thereby seemed to be mediated by a species turnover towards habitat generalists. However, contrary to expectations, we detected no interactive effects between the two drivers. Our results suggest that exotic plants and land-use promote generalist plants and pollinators, while negatively affecting specialized plant–pollinator interactions. Weak integration and high specialization of exotic plants may have prevented interactive effects between exotic plants and land-use. Still, the additive effects of exotic plants and land-use on specialized plant–pollinator interactions would have been overlooked in a single-factor study. We therefore highlight the need to consider multiple drivers of global change in ecological research and conservation management.     

Zur Wirkungsweise des Wuchsstoffes auf das Streckenwachstum der Wurzel

Ohne ZusammenfassungMit 12 Textabbildungen.Dissertation der Naturw.-math. Fakultät der Universität Freiburg i. Br.     

Problems in assessing multiple cutaneous melanoma. A review on the accuracy of a population based cancer registry

Databases with information on malignant tumors are of great value for epidemiologic studies. From the Regional South Swedish Tumour Registry, which is of documented high quality, 24 patients out of 8008 with reported melanoma diagnosis 1973–2003 were reported as having multiple (≥3) primary, invasive cutaneous malignant melanomas (CMM). Of the 76 tumours identified in these patients, 7 (9%) were found not to be invasive melanomas. Additional cases could be put into question since the lesions could be interpreted as epidermotropic metastases, a diagnosis which can be difficult to establish reliably by microscopic examination. Among the 24 patients we could also identify 8 (10%) additional lesions representing invasive CMM, not included in the Tumour Registry database. Thorough information concerning an earlier melanoma diagnosis and its site of presentation is needed from the clinician and the pathologist for optimal assessment of the histology and the prognostication of the patient, as well as proper reporting to a tumour registry. Identifying multiple primary malignant melanomas is also of special importance for counselling patients belonging to families with hereditary disease. In this study it is shown that diagnosing and reporting multiple malignant melanomas can be problematic due to insufficient communication and to the rare and deceptive capability of cutaneous metastases to imitate primary tumours.     

Hereditary hypophosphatemic rickets with hypercalciuria is caused by mutations in the sodium-phosphate cotransporter gene SLC34A3

Hypophosphatemia due to isolated renal phosphate wasting results from a heterogeneous group of disorders. Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is an autosomal recessive form that is characterized by reduced renal phosphate reabsorption, hypophosphatemia, and rickets. It can be distinguished from other forms of hypophosphatemia by increased serum levels of 1,25-dihydroxyvitamin D resulting in hypercalciuria. Using SNP array genotyping, we mapped the disease locus in two consanguineous families to the end of the long arm of chromosome 9. The candidate region contained a sodium-phosphate cotransporter gene, SLC34A3, which has been shown to be expressed in proximal tubulus cells. Sequencing of this gene revealed disease-associated mutations in five families, including two frameshift and one splice-site mutation. Loss of function of the SLC34A3 protein presumably results in a primary renal tubular defect and is compatible with the HHRH phenotype. We also show that the phosphaturic factor FGF23 (fibroblast growth factor 23), which is increased in X-linked hypophosphatemic rickets and carries activating mutations in autosomal dominant hypophosphatemic rickets, is at normal or low-normal serum levels in the patients with HHRH, further supporting a primary renal defect. Identification of the gene mutated in a further form of hypophosphatemia adds to the understanding of phosphate homeostasis and may help to elucidate the interaction of the proteins involved in this pathway.     

Phloem loading in two Scrophulariaceae species. What can drive symplastic flow via plasmodesmata?

To determine the driving forces for symplastic sugar flux between mesophyll and phloem, gradients of sugar concentrations and osmotic pressure were studied in leaf tissues of two Scrophulariaceae species, Alonsoa meridionalis and Asarina barclaiana. A. meridionalis has a typical symplastic configuration of minor-vein phloem, i.e. intermediary companion cells with highly developed plasmodesmal connections to bundle-sheath cells. In A. barclaiana, two types of companion cells, modified intermediary cells and transfer cells, were found in minor-vein phloem, giving this species the potential to have a complex phloem-loading mode. We identified all phloem-transported carbohydrates in both species and analyzed the levels of carbohydrates in chloroplasts, vacuoles, and cytoplasm of mesophyll cells by nonaqueous fractionation. Osmotic pressure was measured in single epidermal and mesophyll cells and in whole leaves and compared with calculated values for phloem sap. In A. meridionalis, a 2-fold concentration gradient for sucrose between mesophyll and phloem was found. In A. barclaiana, the major transported carbohydrates, sucrose and antirrhinoside, were present in the phloem in 22- and 6-fold higher concentrations, respectively, than in the cytoplasm of mesophyll cells. The data show that diffusion of sugars along their concentration gradients is unlikely to be the major mechanism for symplastic phloem loading if this were to occur in these species. We conclude that in both A. meridionalis and A. barclaiana, apoplastic phloem loading is an indispensable mechanism and that symplastic entrance of solutes into the phloem may occur by mass flow. The conditions favoring symplastic mass flow into the phloem are discussed.