) a- i) ]# U, g$ [) z6 OAM真菌在生态系统中的作用$ r- s6 N1 B2 A' w0 x
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Forests accumulate and store large amounts of carbon (C), and a sub " x. \7 n5 H4 c* A, O% G. a9 U' bstantial fraction of this stock is contained in deadwood. This transient pool is subject ! S* \% B2 v0 J9 y/ ]% Lto decomposition by deadwood-associated organisms, and in this process it contrib i4 V9 d! @ I* u' {
utes to CO2 * _$ s2 ]7 R- eemissions. Although fungi and bacteria are known to colonize dead 2 L; T. Z: g6 K" e. O: }& O& i H& Ewood, little is known about the microbial processes that mediate carbon and nitro ; P' k( i$ p5 |2 W: Kgen (N) cycling in deadwood. In this study, using a combination of metagenomics, 7 |" {# A, G! [% {metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom 5 G7 j: R4 p" r* L5 J v3 B; W2 tposition of deadwood reflflects the complementary roles played by fungi and bacteria.7 h2 n5 B0 Z0 g' V0 m4 h+ p
Fungi were found to dominate the decomposition of deadwood and particularly its re " _4 _( v- E* N5 _! _1 B4 lcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead . Z- f' \9 a3 G5 Bwood through N fifixation, being dependent on fungal activity with respect to deadwood 7 {( H% e7 e3 }. Ecolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con 4 @0 J# M( @/ ?- L) c, H1 Rstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation* A4 { G/ z: r: s8 @! _
that are a result of a joint action of deadwood bacteria and fungi may be signifificant for- S V" H- {5 N2 N* L
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead5 B0 v$ ~4 A' ^* |7 C
wood retention may help to improve the nutritional status and fertility of soils. / N% Q8 ^) t) ]$ [% O& @ & w$ `! O( g; ]. R- J! U- |! X9 n( Q. K- [# @