Litter nutrients and retranslocation in a central African rain forest dominated by ectomycorrhizal trees

In the strongly seasonal, but annually very wet, parts of the tropics, low-water availability in the short dry season leads to a semi-deciduous forest, one which is also highly susceptible to nutrient loss from leaching in the long wet season. Patterns in litterfall were compared between forest with low (LEM) and high (HEM) abundances of ectomycorrhizal trees in Korup National Park, Cameroon, over 26 months in 1990–92. Leaf litter was sorted into 26 abundant species which included six ectomycorrhizal species, and of these three were the large grove-forming trees Microberlinia bisulcata, Tetraberlinia bifoliolata and Tetraberlinia moreliana. Larger-tree species shed their leaves with pronounced peaks in the dry season, whereas other species had either weaker dependence, showed several peaks per year, or were wet-season shedders. Although total annual litterfall differed little between forest types, in the HEM forest (dominated by M. bisulcata) the dry-season peak was more pronounced and earlier than that in the LEMforest. Species differed greatly in their mean leaf litterfall nutrient concentrations, with an approx. twofold range for nitrogen and phosphorus, and 2.5–3.5-fold for potassium, magnesium and calcium. In the dry season, LEM and HEM litter showed similar declines in P and N concentration, and increases in K and Mg; some species, especially M. bisculcata, showed strong dry-wet season differences. The concentration of P (but not N) was higher in the leaf litter of ectomycorrhizal than nonectomycorrhizal species. Retranslocation of N and P was lower among the ectomycorrhizal than nonectomycorrhizal species by approx. twofold. It is suggested that, within ectomycorrhizal groves on this soil low in P, a fast decomposition rate with minimal loss of mineralized P is possible due to the relatively high litter P not limiting the cycle at this stage, combined with an efficient recapture of released P by the surface organic layer of ectomycorrhizas and fine roots. This points to a feedback between two essential controlling steps (retranslocation and mineralization) in a tropical rain forest ecosystem dominated by ectomycorrhizal trees.

Does proximity to conspecific adults influence the establishment of ectomycorrhizal trees in rain forest?

Three ectomycorrhizal legume trees, Microberlinia bisulcata, Tetraberlinia bifoliolata and T. moreliana, form discrete groves in the southern part of Korup National Park, in southwest Cameroon and contribute c. 45–70% of stand basal area locally in a matrix of otherwise species-rich arbuscular mycorrhizal forest. A transplant experiment was performed to assess the importance of ectomycorrhizal infection associated with proximity to parents in seedling establishment of the grove-forming species. Nonectomycorrhizal seedlings of the three species were transplanted into plots of two forest types, one of high (HEM, within-grove) and one of very low (LEM, outside the grove) abundance of all three species as adult trees. For two species (T. moreliana and M. bisulcata) there was no difference in survival over 16 months, but for the third (T. bifoliolata) survival was best in HEM forest, and correlated with the basal area of adult trees of ectomycorrhizal species. Only one species (T. moreliana) increased in biomass over the experimental period; the others declined. There was no effect of forest type on overall growth of any species, but the survivors of two (T. moreliana and M. bisulcata) had heavier stems in the HEM forest. Differences in survival and growth of transplants between the three species were in accord with the ecology of the species as inferred from the frequency distributions of adult tree size in the forest. Seedlings became infected with ectomycorrhizas in both forest types; where there was a difference in extent of infection (T. moreliana) this was not related to survival or growth; and where there was a difference in survival (T. bifoliolata) this was not related to extent of infection. These results confirm that mycorrhizal inoculum associated with conspecific adults is neither a prerequisite nor a guarantee of seedling establishment, but indicates that in some circumstances there might be benefits of being close to parents. Further research is required to unravel the complexities of ectomycorrhizal community structure in this spatially and temporally heterogeneous forest, and to clarify the extent to which the various hosts share ectomycorrhizal partners.

Field investigation of dried lakes in western United States as an analogue to desiccation fractures on Mars

Potential Desiccation Polygons (PDPs), tens to hundreds of meters in size, have been observed in numerous regions on Mars, particularly in ancient (>3Gyr old) terrains of inferred paleolacustrine/playa geologic setting, and in association with hydrous minerals such as smectites. Therefore, a better understanding of the conditions in which large desiccation polygons form could yield unique insight into the ancient climate on Mars. Many dried lakebeds/playas in western United States display large (>50m wide) desiccation polygons, which we consider to be analogues for PDPs on Mars. Therefore, we have carried out fieldwork in seven of these dried lakes in San Bernardino and the Death Valley National Park regions complemented with laboratory and spectral analysis of collected samples. Our study shows that the investigated lacustrine/playa sediments have (a) a soil matrix containing 40-75% clays and fine silt (by volume) where the clay minerals are dominated by illite/muscovite followed by smectite, (b) carbonaceous mineralogy with variable amounts of chloride and sulfate salts, and significantly, (c) roughly similar spectral signatures in the visible-near-infrared (VIS-NIR) range. We conclude that the development of large desiccation fractures is consistent with water table retreat. In addition, the comparison of the mineralogical to the spectral observations further suggests that remote sensing VIS-NIR spectroscopy has its limitations for detailed characterization of lacustrine/playa deposits. Finally, our results imply that the widespread distribution of PDPs on Mars indicates global or regional climatic transitions from wet conditions to more arid ones making them important candidate sites for future in situ missions.

Na 1 Nachlass Max Horkheimer, 17 - Korrespondenzen u.a. mit M. Gosling (p. I 9, 1-159)

11 Briefe zwischen M. Gosling und Max Horkheimer, 1935-1938; 1 Brief von Ellen Gottschalk an 04.08.1936; 1 Brief von Brill an Max Horkheimer, 15.08.1936; 2 Briefe zwischen Louise Gottschalk und Max Horkheimer, 06.12.1937, 19.04.1937; 3 Briefe zwischen Max Gottschalk und Max Horkheimer, 1941, 23.01.1941; 2 Briefe zwischen Nemes Gottschalk und Max Horkheimer, 29.03.1939, 03.04.1939; 2 Briefe zwischen Lawrence Gould und Max Horkheimer, 12.01.1947, 04.01.1947; 4 Briefe zwischen Isaeque Graeber und Max Horkheimer, 20.07.1941, 1941; 4 Briefe zwischen Malborne W. Graham und Max Horkheimer, 17.10.1940, 1940; 1 Brief von Max Horkheimer an J. A. C. Grant, 23.10.1940; 2 Briefe zwischen dem Grant Grove Lodge Kings Canyon National Park California und Max Horkheimer, 30.09.1946, 04.10.1946; 4 Brefe zwischen Liesel Gras und Max Horkheimer, 1948, 02.04.1948; 2 Briefe zwischen Claire F. Gravel und 23.03.1942, 26.03.1942; 1 Brief und 4 Briefentwürfe von Max Horkheimer an Edward S. Greenbaum, 20.06.1940; 13 Briefe zwischen B. Groethuysen und Max Horkheimer, 1935-1937; 1 Hochzeitsanzeige von Isabelle Grossen, 26.11.1938; 1 Brief von Max Horkheimer an Isabelle Grossen, 17.12.1938; 1 Brief von Kurt Grossmann an Max Horkheimer, 29.12.1939; 3 Briefe von Eva Grosz an Max Horkheimer, 1937; 5 Briefe zwischen Franz M. Groedel und Max Horkheimer, 1939, Oktober 1939; 7 Briefe zwischen Emil Grünberg und Max Horkheimer, 1935-1940; 1 Brief von B. M. Telders an Max Horkheimer, 27.09.1938; 3 Briefe zwischen dem Academic Assistance Council London und Max Horkheimer, 1935, 29.03.1935; 1 Briefentwurft von Max Horkheimer an Karl Grünberg, 07.02.1936; 1 Brief von Juliette Favez an Max Horkheimer, 07.02.1936; 3 Briefe zwsichen Martin Grünberg und Max Horkheimer, November 1938, 18.11.1938; 3 Briefe zwischen Alfred Grünebaum und Max Horkheimer, 10.01.1939, 1939; 2 Briefe zwischen D. E. Grünebaum und Max Horkheimer, 24.11.1940, 02.12.1940; 3 Briefe zwischen Richard Güldenstein und Max Horkheimer, August 1937, 17.08.1937; 1 Brief von Daniel Guérin an Max Horkheimer, 13.07.1947; 1 Brief von Max Horkheimer an Guerro, 08.09.1936;

Propiedades químicas de suelos desarrollados sobre distintos materiales originales bajo bosques de Austrocedrus chilensis

En este trabajo se caracterizaron las propiedades químicas del horizonte A de los suelos desarrollados a partir de distintos materiales originarios, sobre los cuales habitan bosques de Austrocedrus chilensis. Se seleccionaron cinco sitios, ubicados en el Valle 16 de Octubre y en el Parque Nacional Los Alerces de la Provincia del Chubut, Argentina. De cada sitio se tomaron muestras compuestas del horizonte A para la caracterización de las propiedades químicas. Todos los suelos analizados presentaron elevados contenidos de materia orgánica y nitrógeno. Los suelos originados a partir de materiales glaciarios presentaron los máximos valores de bases de intercambio, capacidad de intercambio catiónico y contenido de fósforo, diferenciándose significativamente de los suelos volcánicos. Dentro de los suelos volcánicos se detectaron diferencias en función de la granulometría del material: los suelos derivados de ceniza (< 2mm) tendieron a presentar mayores valores de capacidad de intercambio catiónico y bases de intercambio que los suelos de pumita (> 2mm).

Modelos de desarrollo, poblamiento y frontera : el caso del Parque Nacional Nahuel Huapi

Fil: Matossian, Brenda. Consejo Nacional de Investigaciones Científicas y Técnicas

Chemical anlysis of plant communities from Southern Italy

A phytosociological study was conducted in the National Park of Alta Murgia in the Apulia region (Southern Italy) to determine the adverse effects of metal contamination of soils on the distribution of plant communities. The phytosociological analyses have shown a remarkable biodiversity of vegetation on non-contaminated soils, while biodiversity appeared strongly reduced on metal-contaminated soils. The area is naturally covered by a wide steppic grassland dominated by Stipa austroitalica Martinovsky subsp. austroitalica. Brassicaceae such as Sinapis arvensis L. are the dominating species on moderated contaminated soils, whereas spiny species of Asteraceae such as Silybum marianum (L.) Gaertn. and Carduus pycnocephalus L. subsp. pycnocephalus are the dominating vegetation on heavily metal-contaminated soils. The presence of these spontaneous species on contaminated soils suggest their potential for restoration of degraded lands by phytostabilization strategy.