Sward management influences fruiting of grassland basidiomycete fungi

The loss of semi-natural grasslands in Europe, largely though ploughing/reseeding and synthetic fertiliser inputs, has caused a severe reduction in the diversity and abundance of grassland macrofungi. Of these, it is the colourful members of the genus Hygrocybe spp. (waxcaps) that have received most conservation attention, with current management prescriptions recommending the avoidance of fertiliser additions and maintenance of a short sward. However, the latter recommendation is based solely on empirical observations and is at odds with management strategies aimed at the conservation of many other groups of biota. In order to test the effect of sward height on macrofungal fruiting, a field experiment was established at a grassland site known to contain diverse populations (>50 species) of grassland fungi. Replicated 80 m2 plots (n = 5) were subjected to mowing at 3 cm or 8 cm either from May or July onwards, as well as a late haycut to 3 cm in September or no mowing at all. Macrofungal fruitbodies were counted in fortnightly surveys during the autumn. Species richness and fruitbody numbers were greatest on plots mown to 3 cm, either continually or following a July haycut, with hardly any fruitbodies formed on uncut plots. Panaeolus acuminatus and Entoloma conferendum showed atypical responses, fruiting most prolifically on 8 cm-cut and September-cut plots respectively. Thus haycutting followed by maintenance of a short sward, a regime also compatible with maintaining diversity of many grassland plants and invertebrates, is conducive to abundant fruiting of diverse grassland fungi. The formation of fruitbodies is important for wider appreciation of these fungi and useful for their routine monitoring but further information about below-ground mycelial dynamics is urgently required.

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► The conservation of grassland macrofungi is of growing concern in habitat management.
► We tested the effects of several sward management on fruiting of Hygrocybe spp.
► Basidiocarp numbers and macrofungal species richness were greatest in short swards.
► Haycutting then mowing to 3 cm, compatible with maintaining other biota, was optimal.