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Valley View University (VVU) is a private university located within the dry forest zone of the Accra plains; an area strongly affected by urban sprawl. The campus covers approx. 105 ha. Considerable portions of it are yet undeveloped and covered with savannah thickets. In 2002, the university has committed itself to become Africa's first "ecological university". In the context of two projects, substantial improvements have been made in terms of sanitation, water supply, energy-saving buildings and organic agriculture. The further development of the campus was designed in a detailed "ecological masterplan". In this context, we carried out a floristic inventory of the savannah thickets and found more than 100 plant species; the majority of which represent the species pool of the unique mixture of dry forest and savannah thicket species, which is typical for the region. As the remainder of dry forests and savannah thickets in the Accra plains become increasingly threatened by urban sprawl and overgrazing, the VVU administration has agreed to preserve the species-rich thickets. This is a valuable contribution to a more sustainable development of the region.
Steppes used to cover large areas of Hungary, but most of this vegetation has since been destroyed. In Central Hungary, some patches have survived on ridges in wet meadows. These habitat complexes face profound land use changes and their optimal management regime is uncertain. We identified seven annually mown steppe and wet meadow types according to their grazing regime and history and aimed to answer the following questions: (1) Does grazing have beneficial effects on mown steppes and wet meadows? (2) Should the presently homogeneous management of neighbouring steppes and wet meadows be maintained? (3) Is annual mowing sufficient in assisting the recovery of steppes and wet meadows on former croplands?
We selected three localities for each of the seven vegetation types and sampled them with 50 quadrats (50 × 50 cm) in each locality, making a total of 1,050 quadrats. Vascular plant diversity relations were evaluated using the total number of species per habitat type (species richness) and the average number of species per quadrat (microsite diversity). The effect of grazing and history on microsite diversity was tested with linear mixed-effect models. We used Redundancy Analysis to disentangle the role of grazing intensity and management history on species composition. Plant species were then sorted into functional groups, and the proportions of these groups were used to evaluate community structure.
Our results indicate that mowing alone cannot maintain as high a diversity as the combination of the two land use types, thus grazing should be introduced to non-grazed areas. Steppes, however, were found more sensitive to the intensity of grazing than wet meadows. Under heavy grazing, no increased microsite diversity was detected in the steppes and the proportion of disturbance indicators tended to increase. In contrast, the same grazing intensity resulted in only positive effects in wet meadows. Thus, uniform land use on adjacent steppes and wet meadows is not recommended but intensive grazing should be stopped on steppes. Secondary steppes were less diverse than primary ones and their community structure was also poorer, whereas wet meadows had a better regeneration potential. Thus, mowing alone is an incomplete tool to restore the plant diversity of secondary steppes; they should also be grazed and/or should be supported by other active interventions.
River corridor plants in Central Europe account for an above-average proportion of endangered species. The main objective of this study was to examine the effects of habitat fragmentation and abiotic conditions on the survival and changes in population size of four endangered, long-lived river corridor plant species (Euphorbia palustris, Pseudolysimachion longifolium, Sanguisorba officinalis, and Senecio paludosus) over the course of at least ten years. We sampled altogether 138 populations in the Weser and Elbe river systems in Northwestern Germany.
Overall, 33% of the populations went extinct during the study period. Extinction rates and changes in population size were related to initial population sizes, but not to population isolation and only marginally so to habitat quality. Large populations (> 100 individuals) had a much higher probability to survive or increase in size (to > 1000 individuals) than smaller populations. There was no general decline in population size in surviving populations, and extinction rates and changes in population size were independent of time. We therefore conclude that the high extinction rates in small populations are best explained by sudden short-term environmental events, such as changes in land use, rather than by long-term negative effects of, for example, genetic deterioration. A projection matrix for the next 117 years, however, predicted that 85% of the surveyed populations will have gone extinct. Since any establishment of new populations in the study area is unlikely owing to the lack of potential habitats and dispersal limitation, river corridor plants will probably continue to decline. Apart from preventing further habitat deterioration it will be crucial to maintain or establish an appropriate management, and to avoid sudden and adverse changes in land use.