Browsing by Author "Raimondo, Domitilla"

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    Open Access
    A climate change vulnerability assessment of 58 Richtersveld plant species
    (2025) Pather, Keyura; Foden, Wendy; Cunningham, Susan; Raimondo, Domitilla
    The Richtersveld is the northernmost region of the Succulent Karoo and is located in the north-western region of South Africa's Northern Cape Province. This region has an incredible arid plant diversity, with both the highest succulent plant diversity and highest rate of endemism in an arid area, globally. It forms part of both a global biodiversity hotspot and a UNESCO world heritage site. However, it is already experiencing significant climate change exposure which is predicted to worsen. Changes in the area's climate are also interacting synergistically with other anthropogenic pressures including mining, poaching and agriculture. The threats to this area, including climate change, are documented but knowledge gaps still remain – especially with regards to plants and climate change vulnerability. In this study I aimed to find which Richtersveld species are the most vulnerable to climate change while trialling a relatively novel approach in this context. I used a trait-based assessment with correlative species distribution model outputs to assess the sensitivity, adaptive capacity and exposure of 58 plant species occurring within the Richtersveld National Park. This included assessing biological, ecological, environmental and spatial traits of species that contribute to climate change vulnerability. Traits were scored based on literature, expert opinion and correlative modelling outputs. Trait scores were then combined using both additive and ordinal methods, creating a best-case scenario where unknowns were assumed to have ‘low' scores, and a worst-case scenario when these were assumed to be ‘high'. These scenarios were applied to both the ordinal and additive scoring methods. For the additive scoring method, there was an additional consideration – trait weighting. It would be inaccurate to assume all traits hold the same importance in determining a species' vulnerability to climate change. Each trait was assigned a weighting based on literature and expert opinion and applied in an additional weighted scoring approach. Therefore, each species had a total of six climate change vulnerability scores: a best-case ordinal, a worst-case ordinal, a best-case unweighted additive, a worst-case unweighted additive, a best-case weighted additive and a worst-case weighted additive score. Under the worst-case ordinal scoring method, 34 species (59 %), were scored as highly vulnerable to climate change. The most vulnerable species were those that consistently scored high vulnerability scores, across all six scoring methods. This included Cheilanthes namaquensis (Not endemic to the region nor the park and Least Concern), Trachyandra ardimontana (almost endemic to park and Endangered), Albuca etesiogaripensis (almost endemic to park and Data Deficient), Ruschia glauca (almost endemic to park and Endangered) and Schwantesia herrei (Richtersveld endemic and Least Concern). I also found a mismatch between species' Red List status and their scores in my climate change vulnerability assessment. This suggests that highly climate change vulnerable species identified in this study currently have a low Red List threat status assigned to them by the responsible conservation organisation. This finding could mean that their status does not accurately reflect their level of conservation risk – especially if climate change is not accounted for. This can cause them to be overlooked in terms of conservation resource provision and decision- making. The IUCN Red List Version 16 Section 12 provides guidelines for assessing climate change vulnerability and its application in determining a species' threat status to climate change. However, its development is relatively recent, and its use is limited, possibly due to the data and technical expertise required. My study provides a possible example of how, even in highly biodiverse region with low data availability, climate change vulnerability assessments may be carried out, and of the value for preventing extinctions. The highest concentration of climate change vulnerable species were found to be in the central western and northern areas of Richtersveld National Park. The spatial representation of these data may aid where within the Park conservation and management can be prioritized. In conclusion, I trialled an approach that has not previously been applied for Richtersveld plants. The approach produced predictions of climate change vulnerability that could be used for conservation. The approach used in this study helped identify species and areas to which climate change conservation measures could be applied. This approach can be applied to other arid areas and aid in climate- related conservation, including in section 12 of the Red Listing Guidelines (Version 16).
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    An assessment of the distribution and conservation status of endemic and near endemic plant species in Maputaland
    (2016) Matimele, Hermenegildo Alfredo; Raimondo, Domitilla; Hoffman, Timm; Timberlake, Jonathan; Lötter, Mervyn; Burrows, John
    The Maputaland Centre of Endemism (MCE), an area stretching from northern-east KwaZulu-Natal in South Africa to the Limpopo River in southern Mozambique, holds more than 2,500 native plant species. Of those, over 203 are endemic or near endemic to this area. However, the current high human population density in MCE, coupled with high population growth, has increased the pressure on the natural resources of the region and threatens the natural vegetation and plant diversity. Therefore, there is a pressing need to fully understand the threats faced by the Maputaland endemic and near endemic plants and to carry out appropriate conservation actions. In this context, the main aim of the study was to document the distribution of the MCE endemic plant species, with particular emphasis on southern Mozambique. The study also aimed to document the threats to these species and to assess their global conservation status using the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria. This was done by gathering historical species distribution data from herbarium specimens and by assessing their current distribution in the field. In addition, a land cover data set was used to evaluate the level of habitat transformation over time. As a result, 13 endemics were assessed, 11 of these species for the first time. Of the 13 species assessed, two were assessed as Least Concern, five as Vulnerable, four Endangered, one Critically Endangered, and one possibly Extinct. MaxEnt models were used to model the potential distribution of the species assessed and to identify hotspots and priority areas for conservation. The priority areas represent sites of greatest overlap, where 50% of all modelled species overlap in their suitable potential distributions. With this approach, priority areas were identified that can be used in conservation planning, protected area expansion, or other conservation projects. This analysis showed that the highest number of the study species (>7) is concentrated within the Licuati Forest, located south of Maputo in Matutuine District, southern Mozambique. The main threat to this area is charcoal extraction and although none of the endemic species are targeted for charcoal production, the impact of the associated habitat destruction on the endemic species is expected to cause severe declines. It is recommended that studies on the dynamics of the Licuati Thicket vegetation are needed, particularly in terms of the impact of charcoal extraction on the endemics.