Conservation importance of ‘waxcaps grasslands':

Waxcaps are amongst the most visible components of UK grassland soil biota (associated with unimproved meadows). Conservation of waxcap grasslands is a priority for SNH, CCW, EN, DENI (genus includes two Red Data List species)

Project aims:

1. To investigate the distribution of FBs (fruiting bodies) of Hygrocybe spp. at Sourhope and to examine in detail the nutritional behaviour of the commoner species.

2. To determine differences in the acquisition of litter and root derived nutrients between species by addition of 15N and 13C enriched substrates.

Hypotheses to be tested:

1. Plot treatments such as N or liming application, which increase nutrient cycling by other soil organisms, will increase the rate of decomposition of more recalcitrant plant polymers and thus inhibit growth and FB production by Hygrocybe spp.

2. Mycelia of species (e.g. H. pratensis) with higher levels of natural abundance 15N isotope are active in the deeper litter layers compared to spp. (e.g. H. conica), whose FBs show lower levels of enrichment.

Methodology:

1. Fortnightly surveying over two fruiting seasons (01-02) and accurate marking of FB location. Correlate FB location with plot treatments and variations in soil characteristics across the site.

2. Mapping of genetic individuals (genets), using AFLP. Use of specific PCR probes to localise mycelia within the soil/litter horizons.

3. Natural abundance 13C and 15N isotope ratios from FBs and adjacent soil/litter will also be measured for FB in rings away from the isotope enriched treatments.

4. 15N-enriched litter (Agrostis capillaris) has been prepared for burial in bags in the field. 13C enrichment in FBs produced near sites of 13CO2 pulses will be analysed.

Stable isotope analysis:

15N and 13C stable isotopes (measured using isotope ratio mass spectrometry) are now widely used in ecology as markers to follow nutrient flows.

The natural abundance of these isotopes can provide clues about the nutritional behaviour of fungi.

Future Work:

15N and 13C pulse labelling during 2002
Use of PCR probes to locate mycelia in soil
Long-term mapping to measure ring growth rates
Examination of other ‘waxcap grassland’ spp. for stable isotope patterns.

Summary:

Our work with stable isotopes of carbon and nitrogen indicate that these fungi are feeding on recalcitrant organic material in the soil, possibly recycling nitogen from these sources back into the soil system.