AM真菌在生态系统中的作用

杨利霞

0 x- x3 |- y8 F! tAM真菌在生态系统中的作用
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! v' {  X$ w4 G5 D( A" J$ `! y& xForests accumulate and store large amounts of carbon (C), and a sub
$ _8 ~( a+ F! fstantial fraction of this stock is contained in deadwood. This transient pool is subject
/ d: E2 ^, z4 L) K! N$ pto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
2 K' C0 e- K0 C4 `emissions. Although fungi and bacteria are known to colonize dead
6 u$ N/ X3 E& y2 Y- L2 mwood, little is known about the microbial processes that mediate carbon and nitro
8 R4 Z; U3 `' V2 P/ l+ rgen (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.
7 b% `& M& x/ a' s& u, aFungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
; Z; Z" Q' j, R0 g$ L* M2 mwood 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
6 m! S! c1 T/ O& I7 l& Pstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
that are a result of a joint action of deadwood bacteria and fungi may be signifificant for
  ], `% v# n0 i' ^: h. [! Anutrient 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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