AM真菌在生态系统中的作用

杨利霞

+ E) b& i. o/ W& ^% CAM真菌在生态系统中的作用
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1 Q/ z* e, }9 G- U1 I6 X, S) TForests accumulate and store large amounts of carbon (C), and a sub
! U2 R6 j3 M' b; H) G6 vstantial fraction of this stock is contained in deadwood. This transient pool is subject
3 Q3 u7 |+ l; O- g+ d! ]  m+ nto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
5 \' g# U2 O3 R# ]' d# H. |emissions. Although fungi and bacteria are known to colonize dead
7 E6 N. Y7 ?4 U, Ewood, little is known about the microbial processes that mediate carbon and nitro
4 B4 M, y& F6 L/ hgen (N) cycling in deadwood. In this study, using a combination of metagenomics,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
' Z3 }$ m% w) r( S6 K6 C% q2 Xposition of deadwood reflflects the complementary roles played by fungi and bacteria.
) z. }8 s. H- g) Q, `2 oFungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
: o" d8 b6 d- J- W7 Hwood 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
2 C8 R, t& {- A0 z  m  ]7 Q' ]straints 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
nutrient cycling at ecosystem levels. Especially in boreal forests with low N stocks, dead
: e7 H2 n9 P0 W2 Q+ \9 Pwood retention may help to improve the nutritional status and fertility of soils.
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