The influence of historical and contemporary landscape structure on plant biodiversity: effects on species and genetics

Abstract

Biodiversity describes diversity at different levels of biological organisation, including: habitat diversity; species diversity; and genetic diversity. Understanding the processes that contribute to maintaining biodiversity is a primary concern for both ecology and evolutionary biology. To this end, research into the factors influencing the different levels of biodiversity independently are widespread. However, little is understood about the relationship between the different levels. This study investigates the patterns of habitat, species, and genetic diversity in fragmented internationally important calcareous grasslands, and analyses the spatial and temporal factors influencing them. Finally, the relationship between these levels of biodiversity is examined. Within the South Downs National Park study area, substantial change to habitat diversity and landscape structure was measured between the 1930s and 2012. The transition of semi-natural habitat to agricultural land was the predominate change. Loss of habitat between the 1930s and 2012 was found to influence both species richness and species evenness of vegetation in twelve calcareous grassland study sites. By contrast, none of the variables examined explained the variation in species composition between sites. Further analysis, at the genetic level, for two target species showed that the amount of habitat loss was important in explaining the genetic variation in Cirsium acaule, and soil nutrients were important in explaining the variation of Ranunculus bulbosus. In contrast to the predictions of the species genetic diversity correlation theory, no relationship was established between species and genetic diversity. Similarly, no relationships were found between habitat diversity and diversity at the species or genetic level. Although there were similarities in the factors influencing different levels of biodiversity, habitat diversity, species diversity, and genetic diversity appear to be responding independently to the processes acting on them. As such efforts to conserve biodiversity should consider the influence of conservation strategies on biodiversity holistically, and not focus on a single measure.

Date of Award	Mar 2017
Original language	English
Awarding Institution	University of Brighton