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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: O! [3 _7 d, Q! @Forests accumulate and store large amounts of carbon (C), and a sub
stantial fraction of this stock is contained in deadwood. This transient pool is subject
+ X3 H/ z: B$ k' T1 i' o+ @* j) ato decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
# C& V8 P5 ^. C6 r/ _% Rwood, 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,
1 `& O8 r% k7 y5 R& F, _1 [metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
" V- T0 _4 G7 b- [) W2 [# H; s) i$ cposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
/ |& ~% }) o' d0 t% a5 _calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
2 C( w* E# t. J- H% a9 |2 cwood through N fifixation, being dependent on fungal activity with respect to deadwood
5 W) F/ c3 ]4 C3 }; I0 V. ncolonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
% p0 e7 M1 j3 T, r" wstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
1 s, _% I" v. pthat are a result of a joint action of deadwood bacteria and fungi may be signifificant for
' Y( ~9 I8 P) Z7 [2 `3 ynutrient 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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