Exploring the past and the present in order to predict the future: herbarium specimens, field data and extinction probability for conservation managers

Doctoral Thesis


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Loss of biodiversity is a global conservation crisis. Environmental change is rapid and biodiversity loss is happening at rates never experienced before. Conservationists must deal with an ever growing responsibility to conserve biodiversity and in addition to this they must also meet recently recognized conservation heritage mandates. In the face of mounting environmental pressure protected areas have been identified as the primary means for saving biodiversity and heritage sites. Protected area managers are constrained by limited time to act and less available resources than in the past. Negative impacts caused by threats such as climate change or land transformation within biodiversity hotspots require research, monitoring and conservation actions to mitigate these threats and save species from extinction. Monitoring species for a trend in population reduction is particularly difficult when protected area management is faced with a large list of species under its custodianship. Exacerbating this problem is the current format of existing data and its accessibility to managers. Conservationists and protected area management now require new and innovative tools for informed decision making and a multidisciplinary approach is required to achieve their expanded mandate. This research sought specifically to expand our knowledge on global plant species loss from both a social heritage and biodiversity perspective. The study was carried out in the context of science as a discipline and the recently recognised mandate of heritage and biodiversity conservation of protected areas. The thesis deals with the epistemology of science, biocultural heritage, extinction probability and species detection in protected areas. This thesis explores herbarium data from a number of points of view, and looks at the value of herbarium collections to plant species survival at a fine scale within protected areas. Work was carried out in national parks in the Fynbos Biome, a biodiversity hotspot in the Cape Province of South Africa, using herbarium and botanical survey data. I draw on historical views to understand the contribution of herbarium specimens to botany. I explore herbarium specimens as objects of information and show that they make numerous contributions through the field of botany to science, in serving as the longest standing record and providing a window to the nature of the physical world at the time when collected. Early botanical collectors may have at times contributed to what are now known as common practices in science such as the practice of repeat sampling and collecting. This thesis highlights the significant value of the vast amount of work undertaken by early botanical collectors and the tremendous value of information gathered at a certain point in history, it emphasises the urgent need for an increased effort by modern explorers and naturalists to once again embark on fieldwork and collections to advance our understanding of the natural world. I then look at the individual narratives of early botanists in relation to extant populations and the heritage contribution of these to individual national parks. Herbarium specimens are well recognised as historic scientific objects. Herbarium specimens become part of the narrative of the collectors which are directly connected with nature and should be recognised as part of the heritage and natural conservation landscape. The localities of extant plant populations connect biodiversity, current protected areas, and the people who visited and lived there. Working in the Agulhas National Park, I located numerous localities still extant within the Park more than 100 years after collection of the herbarium specimen. I illustrate that plant populations, where historic specimens were collected, are historical scientific places with significant biocultural heritage value, they are areas that show the footprint of people on the landscape, and are spaces where society and science came together to generate knowledge. My research reveals that botany (through herbarium specimens) is consistent in its contributions to science, both social and biological, from the role of herbarium specimens in the development of scientific epistemology and practices, to the recognition of historic herbarium specimens and the sites of in situ extant plant populations as biocultural heritage. I recommend that these sites be included in biocultural heritage monitoring activities of protected areas, regardless of the Red List status of the locality species, and in recognition of their heritage contribution. Tackling the loss of diversity requires an understanding of extinction risk in protected areas. I once again interrogate the value of herbarium data. I undertook a desktop quantitative assessment of herbarium data, survey data and a combined dataset. Using the Solow (1993) extinction probability equation I generated mean survival probabilities for species of four of the main fynbos families (Ericaceae, Fabaceae, Proteaceae and Restionaceae) in the Cape Floristic Region. I then interrogate this against the International Union for Conservation Red List status categories. I present results that show how the inaccessibility of the underlying data results in sparse data available to run the extinction probability model, which alters the accuracy of extinction probability results. Whilst accurately inferring the extinction status of a species is important for species conservation, arguably it is more important to determine whether species in protected areas are still there and if they are stable or declining. Through much of this thesis I demonstrate the value of the capturing of detailed information associated with field collection and how this has been extremely useful through the ages. The modern approach to seek swift insights in light of time and budget constraints does not lend itself to the accumulation of usable, reliable data. Modelling may work in data rich situations, but that is not the case here as I show in testing the extinction probability on the flora of Table Mountain National Park. It is currently not feasible to monitor all IUCN Red List species within a protected area given the economic climate most protected areas find themselves in. Pressure on protected areas to monitor all species with a Red List threat status can be reduced by targeting high-priority species for monitoring and those which have the greatest return on investment for the conservation of the species. To achieve this, an increase in financial support for botanical monitoring based on sound fieldwork practices is needed. The work done in this thesis by exploiting current resources for data such as herbarium and survey records found that an indication of extinction risk could not be determined using the data in its current form. The survey data in particular had significant shortcomings in its curation and management, which in turn restricts its use to conservation science. What appears to be needed is better synergy between herbarium and survey data to determine extinction probabilities. The next step is to investigate new practical methods of data collection, collation and storage such as remote sensing, citizen science, and making use of new technologies as they become mainstreamed. The results of my work contribute to our understanding of the current state of data and floral species in case study national parks in South Africa, and provide a basis for using quantitative approaches to inform conservation decision-making. Lastly, I adapt and develop methods for in-field detection of threatened plant species for the finer scale landscapes of protected areas to inform conservation management decisions. The combination of herbarium and survey data did provide for a clear in-field status to be obtained and it was possible to verify a species as extant at its known subpopulation localities, but more importantly whether a reduction in species subpopulations had occurred. I found no correlation between the Red List status of a species at a broad scale and the actual status of that species in the Table Mountain National Park. I demonstrate that although a species may occur in a protected area it is not necessarily secure if its subpopulations are being lost. Therefore, species that are declining in a protected area should be monitored and action taken to prevent loss irrespective of their Red List status. This thesis articulates the degree to which the IUCN Red List does not align with extinction predictions or in-field survival of species within a protected area. I suggest that the next stage of the Red List development is in setting small scale limits on how to prioritise actions and monitoring in small geographically defined areas. This work highlights the importance of selecting an in-field detection method that is suitable to meet the multiple needs of conservation management (resources and capacity) and to help prioritise which Red Listed species may not necessarily be under immediate threat and can survive with less regular and intense monitoring whereas others with lower Red List rankings may require immediate attention. Herbarium data clearly speak to the wider conservation mandates that have recently emerged. My work shows the multi-layered contribution of herbarium data from global scientific practices and epistemologies, to local heritage contributions in national parks, to informing and guiding species detection and in-field work. Broadly the work shows that this is a highly valuable source of data, which should be fostered and grown. There is a need to revive the role of the field-biologist, to reinitiate a period of collection, data gathering and knowledge generation. Current herbarium and survey data provide a present temporal scale, by employing both of these data, species declines can be found and possibly future extinction can be forecast, enabling conservation actions to be put in place. My work highlights the current situation protected areas find themselves in, with recognition of the biodiversity crisis, fiscal constraints, and data limitations imposed on them. One of the biggest benefits in using herbarium data is the long-term history of the records, coupled with accurate vegetation survey data, this combined dataset could hold unknown potential for use in conservation planning and assessments. By combining in-field survey data, long-term and historic data accurate predictions may be obtained and result in conservation efforts maximised and implementation by protected area management where it counts.