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Stress tolerance of Ranunculus acris and Sanguisorba officinalis

Winter, D.J. (2003) Stress tolerance of Ranunculus acris and Sanguisorba officinalis. Master's Thesis / Essay, Biology.

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Nature development is a new feature in nature conservation. In nature development large areas are turned into core areas containing target vegetation. A target vegetation contains different plant species. Some of these species are common and other are rare. In this research the attention goes to a rare species: Sanguisorba officinalis, and a more common one: Ranunculus acris. The aim of the present experiment is to determine whether a difference in tolerance to certain stress factors can explain the fact that San guisorba officinalis is a rare species and Ranunculus acris a more common one. The tolerance of these two plant species is tested by exposing them to two a-biotic stress factors: high chloride levels and sulphide. Competition for light between plants is simulated by reducing the light level. These three factors were introduced to plants growing on three soil types; clay, peat or sand to relate the experiment to a nature development project in Midden-Groningen (The Netherlands). By exposing the plans to these three factors the hypothesis is tested that the light level is the main factor determining plant establishment. According to analysis suiphide production did not occur however, but the other two stress factors were present. The results show that a high chloride level (10.6 mmol/l) is a stress factor that affected the biomass production and the survival of both species. Reducing the light level on the other hand did not have an effect on these parameters. This factor resulted mainly in adaptations of plants to shading; such as investments in length growth and in leaf area. Ranunculus acris showed a pronounced preference for the clay soil. On the other soil types it showed a very low survival. Summarising Ranunculus acris was more affected by the stress factors than Sanguisorba officinalis. This means that in this case the common species was less tolerant than the rare species. Therefore the hypothesis that this species is rare because it has a lower tolerance has to be rejected. The 'rareness' of San guisorba may be caused by differences in tolerance towards other (stress)factors, differences to the stress factors (in the present experiment) in other life stages or problems in dispersal. A reduced light level did not affect the plants as negatively as the higher chloride level. In this case the light level is not the main factor determining plant establishment. The fact that the plants showed problems when faced with high chloride and/or sulphate levels when grown on the different soil types may imply that these species will encounter problems when introduced to the project area of Midden-Groningen, where the same conditions can be found.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:31
Last Modified: 15 Feb 2018 07:31

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