Climate Change Effects on Terrestrial Ecosystem Processes and Fungal Ecology

Processes of Decomposition: Includes leaching, volatilization, comminution, non-enzymic chemical changes, and catabolism.
Major Catabolism Agents: - Basidiomycetes are the primary decomposers of lignocellulose. - Soil fauna includes Acari, Collembola, Protura, Diplura, Symphyla, Enchytraeidae, Isoptera, Amphipoda, Isopoda, Chilopoda, Diplopoda, Coleoptera, Araaneida, and Mollusca.
Factors Affecting Decay Rate: Metabolism and community structure are influenced by temperature ( $T$ ), water regime, gaseous regime, lignin and polyphenols, and the $C:nutrient$ ratio.

Decay Constant ( $k$ ) and Turnover: Decay rates vary significantly across ecosystems (data from Rodin & Basilevic and Whittaker): - Tundra: $k = 0.03\,yr^{-1}$ , Turnover time ( $3/k$ ) = $100\,yr$ . - Boreal forest: $k = 0.21\,yr^{-1}$ , Turnover time = $14\,yr$ . - Temperate deciduous forest: $k = 0.77\,yr^{-1}$ , Turnover time = $4\,yr$ . - Tropical forest: $k = 6.0\,yr^{-1}$ , Turnover time = $0.5\,yr$ .
Climate Effects: Climate change alters decay rates through metabolic changes and shifts in community composition.

Dataset: Analysis of fruit body records from Austria, Germany, Spain, Switzerland, The Netherlands, Norway, and the UK.
Autumn Fruiting Season in the UK: The season has doubled in length over the last $60\,yr$ , extending from $33\,d$ in the 1950s to $75\,d$ currently.
Ecological Differences in Fruiting: - Wood decayers: $53\%$ are fruiting earlier. - Ectomycorrhiza: $48\%$ are fruiting later. Mycorrhizal fungi with deciduous trees start later, while those with coniferous trees generally do not, showing physiological differences in climate response.
Spring Fruiting: Since 1975, species like Hypholoma fasciculare have begun fruiting in spring as well as autumn, indicating increased mycelial activity and decay in winter/spring. Earlier spring fruiting correlates with higher winter temperatures.

Latent Propagules: Primary colonizers (endophytes) are latently present in living branches (e.g., Biscogniauxia nummularia in Beech). Specific microclimates influence which species develop; for example, elevated temperature favors B. nummularia and C. puteana.
Host Shifts: Auricularia auricula-judae has expanded its host range from Sambucus nigra (1953) to include species such as Fagus sylvatica (1979), Quercus robur (1998), and Buddleia davidii (2008).
Interspecific Interactions: Outcomes of fungal competition (e.g., H. fasciculare vs P. radiata) change based on temperature ( $20^{\circ}C$ vs $25^{\circ}C$ ).

Grazing Impact: Grazing by collembola (Folsomia candida and Protophorura armata) can negate the effects of elevated temperature on fungal radial extension rates.
Decomposition Rates: While elevated temperature increases wood decay overall (P < 0.001), grazing invertebrates determine the fungal community composition, which indirectly affects decay processes.
Microcosm vs. Reality: In microcosms, grazing influences basidiomycete response to climate change; in realistic systems, macrofauna likely have greater effects than mesofauna.