& k9 r2 d( r, l& jAM真菌在生态系统中的作用8 T0 }) F! u. F( o. G! V
; X' m1 ?0 P+ n* l: ] 0 P6 u8 V) z& W4 k + j4 ?: @9 v( v/ G4 k8 f + Y8 D0 o Z4 v2 C9 {$ i- n3 U( VForests accumulate and store large amounts of carbon (C), and a sub + L- d% G) ~. istantial fraction of this stock is contained in deadwood. This transient pool is subject( y- O; j" n6 {% y
to decomposition by deadwood-associated organisms, and in this process it contrib1 {# @% S8 z# Y6 k* \" I, u7 Y T% M
utes to CO2 + [, f3 }3 b, D2 P8 e$ z5 d3 \
emissions. Although fungi and bacteria are known to colonize dead ; A V# B1 d& i7 h9 ?wood, little is known about the microbial processes that mediate carbon and nitro # c8 I1 x3 R( \& d/ s9 r Agen (N) cycling in deadwood. In this study, using a combination of metagenomics,/ W, O% Y9 j; `) O$ X$ I, h
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom% \. @' G; S- g& J
position of deadwood reflflects the complementary roles played by fungi and bacteria. " N3 M2 Z2 a. O6 H/ {7 ]Fungi were found to dominate the decomposition of deadwood and particularly its re( o1 V9 `; S4 K* Q( t1 H, L" I
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead- ^) k B5 C% N x0 v$ m
wood through N fifixation, being dependent on fungal activity with respect to deadwood . y- l, F* }% \- G5 ~colonization and C supply. Conversely, bacterial N fifixation helps to decrease the con 3 z" @ g+ F O% [straints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation - p3 h( u, d6 \1 F* m8 U8 Dthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for- _. n% t- |, B h: t2 ~
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead2 J. i8 ^2 E" n0 U6 _
wood retention may help to improve the nutritional status and fertility of soils. * W W6 t' ^+ ?) M; l* M8 U 1 s( f) b/ P: C+ E 3 o U8 c' _/ ^7 k