AM真菌在生态系统中的作用

杨利霞

AM真菌在生态系统中的作用


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Forests accumulate and store large amounts of carbon (C), and a sub
# X2 G$ m" e! C, [) ^% Lstantial fraction of this stock is contained in deadwood. This transient pool is subject
. K7 H3 k- Q8 w4 D: F, Ato decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
, Z  \/ y$ R' O/ c& Pemissions. Although fungi and bacteria are known to colonize dead
& d) \& D& V6 U! e+ twood, little is known about the microbial processes that mediate carbon and nitro
gen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
position of deadwood reflflects the complementary roles played by fungi and bacteria.
3 b( B/ e0 I# j* f0 N' UFungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
wood through N fifixation, being dependent on fungal activity with respect to deadwood
; P6 a, C9 d; K+ s2 Ccolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
" `* ^. @8 u5 G5 I* i, ystraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
2 V! y- v7 v, H  s; g$ s; \% lthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
wood retention may help to improve the nutritional status and fertility of soils.

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