Biostratigraphical investigations of Lago d'Averno, near Naples

Remains of diatoms, molluscs, ostracods, foraminifera and pollen exines preserved in the sediments of Lago d'Averno, a volcanic lake in the Phlegrean Fields west of Naples, allowed us to reconstruct the changes in the ecological conditions of the lake and of the vegetation around it for the period from 800 BC to 800 AD. Lago d'Averno was at first a freshwater lake, temporarily influenced by volcanic springs. Salinity increased slowly during Greek times as a result of subsidence of the surrounding land. Saline conditions developed only after the lake was connected with the sea by a canal, when Portus Julius was built in 37 BC. The first post-Roman period of uplift ended with a short freshwater phase during the 7th century after Christ. Deciduous oakwoods around the lake was transformed into a forest of evergreen oaks in Greek times and thrived there - apparently almost uninfluenced by man - until it was felled, when the Avernus was incorporated into the new Roman harbour in 37 BC, to construct a shipyard and other military buildings there. Land-use was never more intense than during Roman times and weakest in Greek and Early Roman times, when the Avernus was considered a holy place, the entrance to the underworld.

Epiphytic orchid diversity found on trees and shrubs in coffee cultivated Afromontane rainforest, SW Ethiopia

The moist evergreen Afromontane forest of SW Ethiopia has become extremely fragmented and most remnants are intensively managed for cultivation of coffee (Coffea arabica). We investigated the distributions of epiphytic orchids in shade trees and their understory in forests with contrasting management intensity to determine biodiversity losses associated with coffee cultivation and to determine the capacity of coffee shrubs to act as refugia for orchid species. We studied epiphytic orchids in managed forests and natural forests and recorded orchid diversity and abundance in different tree zones of 339 trees and in the understory. Coffee management was associated with a downward shift of orchid species as orchid species were occurring in significantly lower tree zones in managed forest. The number of shrubs in the understory of managed forest was not higher than in natural forests, yet orchid abundance was higher in the understory of managed forests. Local extinctions of epiphytic orchids and species losses in the outer tree zones (a contraction of habitat) in managed forests are most likely driven by losses of large, complex-structured climax trees, and changes in microclimate, respectively. Coffee shrubs and their shade trees in managed forests are shown here to be a suitable habitat for only a limited set of orchid species. As farmers continue to convert natural forest into managed forest for coffee cultivation, further losses of habitat quality and collateral declines in regional epiphytic orchid diversity can be expected. Therefore, the conservation of epiphytic orchid diversity, as well as other components of diversity of the coffee forests, must primarily rely on avoiding coffee management intensification in the remaining natural forest. Convincing farmers to keep forest-climax trees in their coffee forest and to tolerate orchids on their coffee shrubs may also contribute to a more favorable conservation status of orchids in Ethiopian coffee agroecosystems.

Age model and pollen analysis from site GIK16867 in the northern Angola Basin

Sporomorphs and dinoflagellate cysts from site GIK16867 in the northern Angola Basin record the vegetation history of the West African forest during the last 700 ka in relation to changes in salinity and productivity of the eastern Gulf of Guinea. During most cool and cold periods, the Afromontane forest, rather than the open grass-rich dry forest, expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the Gulf of Guinea. Except in Stage 3, when oceanic productivity was high during a period of decreased atmospheric circulation, high oceanic productivity is correlated to strong winds. The response of marine productivity in the course of a climatic cycle, however, is earlier than that of wind vigour and makes wind-stress-induced oceanic upwelling in the area less likely. Monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run-off.