Type of site, water supply
The mycelium of Sarcoscypha appears to survive drought for many years (see below). In order to induce fruit-body formation, however, prolonged moisture over several months is required. This may be supported by short-lasting flooding by rivers, but flooding does not take place in most sites. Important is a dense canopy to ensure shading, but much more a shady valley or a N-exposed slope, and a soil which is permanently moist by floating ground water supplying the branches with calcareous water. The branches must more or less be buried in earth or under a layer of litter, or among fallen blocks of rock.
Typical sites are woods along rivers and rivulets, and boggy places, but also valleys and slopes without running water. An earlier opinion that Sarcoscypha is absent from lakes is probably erroneous.
The three European species of Sarcoscypha possess particularly long-lived apothecia which overwinter by growing during the cold months after a developmental period of 4-6 months (Harrington 1997: 54). In contrast to this, S. occidentalis fruits during summer.
S. austriaca (Feb.-May) fruits one or two months after S. coccinea (Nov.-March) while S. jurana (Nov.-May) is somewhat intermediate. This difference in phenology partly originates from the preference of S. austriaca for higher altitudes. However, even when growing at the same site (sympatric), S. coccinea fruited about one month earlier than S. austriaca. While apothecia of S. coccinea and S. jurana may reach their full size already during November, in S. coccinea even with a few asci reaching maturity, those of S. austriaca are yet very small at that time, and are still immature when the other two attained full maturity in February (compare also Pidlich-Aigner 1999, van Duuren 2004, Matočec & Kušan 2007: fig. 4).
Apothecia repeatedly develop from the very same branch over several years. Apothecia can be obtained during the next spring season by burying infected branches (from which the apothecia may be removed) during summer or autumn at shady places, and keeping them moist in the case of a dry winter (Pidlich-Aigner 1999: 10).
Fresh apothecia can be kept alive for several weeks in a tight box together with earth or mosses at a temperature of c. 0-5°C. Likewise, mature apothecia of S. austriaca survive about one month in the field, and apothecia developing during late autumn persist in full size but with immature asci even about four months during the cold season.
Hymenial elements do not survive desiccation even for only one day. However, ascospores were still alive in herbarium material preserved for 26 months or even 8 years! The mycelium inside the branch also appears to survive drought. An odd experiment in front of my house showed that infected branches still contain living mycelium 10 years after placing them unburied outside on the ground. The mycelium within the branches, beneath the blackish stain of the surface, is obviously highly xerotolerant, as it produced fruit-bodies as soon as the branches came slowly underground during these 10 years.
An experiment with S. jurana showed that the ascospores survive -18°C while the asci die off (temperature achieved within 16-18 h starting from room temperature, G. Marson & Baral, ined., Ciboria caucus fully survived this procedure). Despite this single experiment, the occurrence of Sarcoscypha species during the winter months tells for a high frost-tolerance. Although usually covered by snow during winter, S. austriaca was found to survive quite rapid changes in temperature in the field from -15°C at night to a few degrees above zero during the day, and that without being covered by snow (Pidlich-Aigner 1999).
Do Sarcoscypha spores infect living branches?
The observation that the mycelium inside the branches is xerotolerant led me to hypothesize that Sarcoscypha might infect its hosts through living or necrotic branches in the crown and exist as an endophyte inside them. With the death of these branches the mycelium would then decompose the wood core. As we know from the inhabited branches, Sarcoscypha delineates the colonized wood area by a black demarcation line of brown cells. The procedure of wood decay possibly lasts a year or more since the branches dry out during the summer months, and the mycelium therefore needs to survive desiccation during that period. Only when the branches fall to the ground and are permanently moist, e.g., by being covered by snow during winter, fruit-bodies can be formed. Fruit-bodies are known to be repeatedly formed over several years every spring, until the nutrient resources are consumed. During that time mosses overgrow the branches.
Fungi as a food source
Sarcoscypha ascocarps are used by insects (Diptera larvae, Collembola), isopods, and snails (Gastropoda) as food source (Harrington 1990: 425). The red colour of the discs might serve to attract such animals and to support dissemination of ascospores.