Plant Biodiversity Hotspot Research Articles

Niche-based modelling as a tool for predicting the risk of alien plant invasions at a global scale.

Predicting the probability of successful establishment of plant species by matching climatic variables has considerable potential for incorporation in early warning systems for the management of biological invasions. We select South Africa as a model source area of invasions worldwide because it is an important exporter of plant species to other parts of the world because of the huge international demand for indigenous flora from this biodiversity hotspot. We first mapped the five ecoregions that occur both in South Africa and other parts of the world, but the very coarse definition of the ecoregions led to unreliable results in terms of predicting invasible areas. We then determined the bioclimatic features of South Africa's major terrestrial biomes and projected the potential distribution of analogous areas throughout the world. This approach is much more powerful, but depends strongly on how particular biomes are defined in donor countries. Finally, we developed bioclimatic niche models for 96 plant taxa (species and subspecies) endemic to South Africa and invasive elsewhere, and projected these globally after successfully evaluating model projections specifically for three well-known invasive species (Carpobrotus edulis, Senecio glastifolius, Vellereophyton dealbatum) in different target areas. Cumulative probabilities of climatic suitability show that high-risk regions are spatially limited globally but that these closely match hotspots of plant biodiversity. These probabilities are significantly correlated with the number of recorded invasive species from South Africa in natural areas, emphasizing the pivotal role of climate in defining invasion potential. Accounting for potential transfer vectors (trade and tourism) significantly adds to the explanatory power of climate suitability as an index of invasibility. The close match that we found between the climatic component of the ecological habitat suitability and the current pattern of occurrence of South Africa alien species in other parts of the world is encouraging. If species' distribution data in the donor country are available, climatic niche modelling offers a powerful tool for efficient and unbiased first-step screening. Given that eradication of an established invasive species is extremely difficult and expensive, areas identified as potential new sites should be monitored and quarantine measures should be adopted.

Geographic structure of molecular variation of Gentiana ligustica (Gentianaceae) in the Maritime and Ligurian regional hotspot, inferred from ITS sequences

AbstractThe Maritime and Ligurian Alps represent a regional hotspot of plant biodiversity found in the Mediterranean. Historical factors, complex geomorphology and habitat diversity may have played key roles to mould the biogeographical singularity of this area. This study represents the first regional phylogeographic attempt to better assess the complex evolutionary history of an endemic plant (Gentiana ligustica), which is found throughout this hotspot, across a large altitudinal and ecological gradient. Here, we examine how historical and topographical factors have affected the geographic structure of sequence variation at internal transcribed spacers (ITS) of ribosomal DNA. Sequence data revealed a fine‐scale geographical structure of molecular variation, and the presence of contact areas between groups of populations differentiated by ITS ribotypes. A comparison between the sequence distribution and topography suggests that the genetic structure of G. ligustica is the result of isolation and drift. Combined phylogeographic, Pleistocene glaciation, topographic and geologic data suggest the presence of several genetically differentiated refugia, at the margins of the ice sheets in the southern part of the Maritime and Ligurian Alps during the last two glaciations (Riss and Würm), as well as in some valleys and cliffs during the Würm.

Strategic conservation interventions in a region of high biodiversity and high vulnerability: a case study from the Agulhas Plain at the southern tip of Africa

AbstractIn terms of the persistence of biodiversity, the siting of conservation areas has traditionally been ad hoc. In the Cape Floristic Region, a hot-spot of plant biodiversity and endemism, past conservation interventions have led to the mountains being over-represented in the reserve network, while the lowlands have remained very poorly conserved. Ongoing threats to the lowlands such as the rampant spread of invasive alien plants, and land transformation for agriculture and resort development, continue to undermine biodiversity in these regions. A new conservation intervention, the Agulhas National Park, is in the process of being implemented on the coastal lowlands at Africa's southernmost tip. A flexible, reserve-selection design tool is being used to guide this process. The practical challenges in implementing a new protected area in a fragmented landscape, which has a high biodiversity and vulnerability, are examined. The role of different institutions, in partic-in particular state-private partnerships, and current investigations into conservation agencies' policies, legislation and funding mechanisms are dealt with. It is imperative that future conservation planning considers the threats to biodiversity first and foremost. Institutions such as South African National Parks and the Cape Nature Conservation Board must act strategically to avoid changes in land use that will compromise the biodiversity goals of retention and persistence. Conservation efforts will only succeed if institutional and socio-economic considerations are integrated with conservation plans aimed at ensuring the long-term persistence of biodiversity.

Strategic conservation interventions in a region of high biodiversity and high vulnerability: a case study from the Agulhas Plain at the southern tip of Africa

In terms of the persistence of biodiversity, the siting of conservation areas has traditionally been ad hoc. In the Cape Floristic Region, a hot-spot of plant biodiversity and endemism, past conservation interventions have led to the mountains being over-represented in the reserve network, while the lowlands have remained very poorly conserved. Ongoing threats to the lowlands such as the rampant spread of invasive alien plants, and land transformation for agriculture and resort development, continue to undermine biodiversity in these regions. A new conservation intervention, the Agulhas National Park, is in the process of being implemented on the coastal lowlands at Africa's southernmost tip. A flexible, reserve-selection design tool is being used to guide this process. The practical challenges in implementing a new protected area in a fragmented landscape, which has a high biodiversity and vulnerability, are examined. The role of different institutions, in partic-in particular state-private partnerships, and current investigations into conservation agencies' policies, legislation and funding mechanisms are dealt with. It is imperative that future conservation planning considers the threats to biodiversity first and foremost. Institutions such as South African National Parks and the Cape Nature Conservation Board must act strategically to avoid changes in land use that will compromise the biodiversity goals of retention and persistence. Conservation efforts will only succeed if institutional and socio-economic considerations are integrated with conservation plans aimed at ensuring the long-term persistence of biodiversity.

Does Diversity Lure Invaders?

ECOLOGY Richard Gallagher ALBUQUERQUE, NEW MEXICO-- Ecologists have long figured that diverse landscapes should be more resistant to exotic plant invaders, because their array of species does a better job of using up all the available resources like nitrogen and sunlight. But new studies described at a joint meeting here of the Nature Conservancy and the Ecological Society of America suggested that hot spots of plant biodiversity are sometimes magnets for invading weeds, perhaps because good growing conditions favor both native species and exotics alike.