Mast seeding in European beech (Fagus sylvatica L.) is associated with reduced fungal sporocarp production and community diversity

A time series of seed production data from European beech (Fagus sylvatica) was combined with a fungal census (1977 to 2006) from La Chanéaz Fungus Reserve to evaluate the relationship between mast seeding and fungal resource availability. Annual fungal species' counts, traits, contemporaneous weather and seed production data are available here, alongside the code used to complete the analyses.

Methods
The fungal census was conducted in the 75-hectare La Chanéaz Fungal Reserve, established in 1975, near Payerne, Switzerland (Swiss Federal Institute for Forest, Snow and Landscape Research WSL; 46 degrees 47’ 55” to 46 degrees 48’ 10” N and 6 degrees 59’ 52” to 7 degrees 00’ 30” E (Straatsma et al. 2001). The site is an old-growth forest on the Swiss Central Plateau (mean altitude 585-m), dominated by multi-story beech (Fagus sylvatica), with interspersed spruce (Picea abies), larch (Larix decidua), oak (Quercus robur), pine (Pinus sylvestris and Pinus strobus), maple (Acer pseudoplatanus) and ash (Fraxinus excelsior) growing on calcaric cambisol. The study area was enclosed by 2-m fences to deter mushroom pickers and other animals from harvesting the fruiting fungi. From 1975–2006, a total of 115,417 epigeous sporocarps from fungi with macroscopic sporocarps were recorded and identified. Surveys were conducted on a weekly basis, during the May to November growing season, among five 300 m2 plots. These plots were subdivided into three 100 m2 subplots, each of which experienced a distinct mushroom surveying / harvesting procedure: picking, cutting, and no harvest. From the years 1980–1983, only edible species were recorded.

European beech seed production data were compiled from the MASTREE+ database (10.1111/gcb.16130). We compiled all >5-year records of seed production within the ‘southern region’ identified by Vacchiano et al (2017, 10.1111/nph.14600) resulting in 80 unique time series of beech seed production.  To combine these datasets, we standardized each dataset to its range, resulting in a seed production score from 0-1 for each year. We used the annual mean of datasets as the region-level index of mast seeding.

Historical daily precipitation and temperature data from 1977–­2006 were compiled from the nearest weather station (Meteo Payerne, 7 km away; 46 degrees 48’ 42” N, 6 degrees 56’ 33” E; 490 m altitude) of the Federal Office of Meteorology and Climatology, MeteoSwiss (http://www.meteoschweiz.admin). Daily temperature and precipitation were averaged across the years. 

Fungal traits for all taxa were compiled from Knudsen and Vesterholt (2008) and Breitenbach and Kränzlin (1991, 1994, 2000, 2005). The following sporocarp traits were extracted from the texts: nutritional mode or guild (i.e., saprotroph or ectomycorrhizal), mean spore breadth and volume, calculated from spore breadth and length assuming an ellipsoidal shape, mean cap area calculated from mean diameter, sporocarp biomass calculated from mean cap area. The FungalTraits database and expert knowledge were also used to assign guild to species (10.1007/s13225-020-00466-2).