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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: Q- z- O+ N( V; m9 g/ q1 QForests accumulate and store large amounts of carbon (C), and a sub
- m. Q7 z; i5 ]$ ]. p: f- ustantial fraction of this stock is contained in deadwood. This transient pool is subject
  h+ `: K% I8 X( c  zto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
emissions. Although fungi and bacteria are known to colonize dead
+ I( i0 V9 w5 V) W  V. h6 pwood, little is known about the microbial processes that mediate carbon and nitro
- {4 u9 f, B2 V# ggen (N) cycling in deadwood. In this study, using a combination of metagenomics,
% M. K, `# R' F; ~metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
- q# k0 W- k3 S/ c4 i. {, c! c7 Zposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
5 }' S" x, O5 x6 Mcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
8 h- i) O0 s' zwood through N fifixation, being dependent on fungal activity with respect to deadwood
colonization and C supply. Conversely, bacterial N fifixation helps to decrease the con
) V/ w3 b, k( E( Ostraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
+ Z! O' P7 _. ~( H4 Rthat 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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