A friend in need...? The facilitative properties of Juncus maritimus on Elytrigia atherica under different levels of biotic and abiotic stress.

Winkel, A. R. te (2014) A friend in need...? The facilitative properties of Juncus maritimus on Elytrigia atherica under different levels of biotic and abiotic stress. Master's Thesis / Essay, Biology.

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Abstract

The Stress Gradient Hypothesis states that a negative or competitive neighbor interaction between species will switch to a positive or facilitative one, with increasing environmental stress. In a field experiment on the Dutch barrier island of Schiermonnikoog we made an attempt to isolate and define the influence of biotic and abiotic stress, in the form of grazing cattle and inundation respectively, on the neighbor interaction between two salt marsh plants: Juncus maritimus, a unpalatable rush largely avoided by grazing cattle, and Elytrigia atherica, a grass which is strongly associated with patches of Juncus under the presence of grazing cattle, but omnipresent without grazing pressure. Cuttings of two different ecotypes of Elytrigia (low and high marsh) were planted in and out of the patches and within the borders of the patch with vegetation removed at ground level. The cuttings were planted on the high and low marsh and either with or without exclosures, to determine the effect of both abiotic stress in the form of high salinity and low oxygen levels in the soil, because of inundation and biotic stress in the form of grazing. We found a strong positive association of Elytrigia with Juncus patches under high local abiotic levels, regardless of grazing pressure, but no conclusive evidence for a negative association under low local abiotic stress. Additionally we found evidence for some level of local adaptation to local abiotic stress levels.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Biology
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:02
Last Modified:	15 Feb 2018 08:02
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/12413

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