Simulated nitrogen deposition affects wood decomposition by cord-forming fungi

Abstract

Anthropogenic nitrogen (N) deposition affects many natural processes, including forest litter decomposition. Saprotrophic fungi are the only organisms capable of completely decomposing lignocellulosic (woody) litter in temperate ecosystems, and therefore the responses of fungi to N deposition are critical in understanding the effects of global change on the forest carbon cycle. Plant litter decomposition under elevated N has been intensively studied, with varying results. The complexity of forest floor biota and variability in litter quality have obscured N-elevation effects on decomposers. Field experiments often utilize standardized substrates and N-levels, but few studies have controlled the decay organisms. Decomposition of beech (Fagus sylvatica) blocks inoculated with two cord-forming basidiomycete fungi, Hypholoma fasciculare and Phanerochaete velutina, was compared experimentally under realistic levels of simulated N deposition at Wytham Wood, Oxfordshire, UK. Mass loss was greater with P. velutina than with H. fasciculare, and with N treatment than in the control. Decomposition was accompanied by growth of the fungal mycelium and increasing N concentration in the remaining wood. We attribute the N effect on wood decay to the response of cord-forming wood decay fungi to N availability. Previous studies demonstrated the capacity of these fungi to scavenge and import N to decaying wood via a translocating network of mycelium. This study shows that small increases in N availability can increase wood decomposition by these organisms. Dead wood is an important carbon store and habitat. The responses of wood decomposers to anthropogenic N deposition should be considered in models of forest carbon dynamics.

Wood decomposition is more rapid on than off termite mounds in an African savanna

“…Though not yet studied in tropical savannas, experiments on wood decomposition frequently indicate sensitivity to scarce or unavailable nutrients (notably nitrogen and phosphorus, e.g., Bebber et al. , Gora et al. ).…”

Transformation and stabilization of pyrogenic organic matter in a temperate forest field experiment

“…N addition has decreased (Fog, 1988;Turunen et al, 2004;Waldrop et al, 2004;Janssens et al, 2010), increased (Mack et al, 2004;Waldrop et al, 2004;Bragazza et al, 2006), or had no effect on (Knorr et al, 2005) SOM decomposition rates. These studies observed increased (Micks et al, 2004;Wal et al, 2007;Allison et al, 2009;Bebber et al, 2011) or level (Mccoll & Powers, 1998) decomposition rates for wood, with no effect on PyOM . These studies observed increased (Micks et al, 2004;Wal et al, 2007;Allison et al, 2009;Bebber et al, 2011) or level (Mccoll & Powers, 1998) decomposition rates for wood, with no effect on PyOM .…”

Size matters: What have we learnt from microcosm studies of decomposer fungus–invertebrate interactions?

“…The rate of fungal utilisation of colonised wood depends, at least in part, on extra- (Table S1). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 (Bebber et al, 2011). Enzymatic changes and wood decomposition, therefore, mirror specific fungal responses to short-term invertebrate grazing, in soil microcosms.…”