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Molinia encroachment is considered a major threat to moorland and heathland conservation in Europe, and there is a need to develop management strategies to control Molinia and restore Calluna moorland. Here we combined weed control and restoration treatments into an integrated land management strategy (ILMS) to provide a more sympathetic approach than previous prescriptions. We applied the following treatments in factorial combination to a Molinia-dominated moorland in the Yorkshire Dales: grazing (ESA prescription level versus no grazing), cutting (0, 1, 2 and 3 cuts), ±application of a graminicide and ±Calluna brash addition. The response of the vegetation was assessed for four years. These data were analyzed using a combination of univariate and multivariate analysis of variance based on constrained ordinations but combined with bivariate standard deviational ellipses. This combined approach was extremely useful in identifying trends in this complex dataset. The only treatment that had consistent effects in the univariate analysis of variance was cutting, where there was increased bare ground, reduced vegetation height, increased species diversity and reduced Molinia cover. Cutting three times had the greatest effect, maintaining a reduced Molinia cover over four years. The multivariate analysis showed that there were important community level interactions. Grazing generally produced vegetation which had a greater moorland species complement. Where grazing was restricted the vegetation had a greater component of Molinia and other acid grassland species. The most effective treatment was the grazed plots, cut thrice, which maintained a low Molinia cover for longest and had less variation in moorland species in the fourth year. Graminicide and brash application had marginal effects on species composition, but the best plots were those given herbicide alone, or in combination with brash addition. These results contrast with other studies, where non-selective herbicide treatment and Calluna addition were required to obtain Molinia control and Calluna regeneration. However, great variation has been found between sites, and managers should be prepared to tailor ILMS for their own site. This is likely to require a knowledge of the initial floristic composition, seed banks and experimentation. |
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