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
stantial fraction of this stock is contained in deadwood. This transient pool is subject
to decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
+ G& y% H+ H. u- @) B' vemissions. Although fungi and bacteria are known to colonize dead
wood, little is known about the microbial processes that mediate carbon and nitro
; Y: X+ g: B4 E* w7 ?4 m( Igen (N) cycling in deadwood. In this study, using a combination of metagenomics,
  N. s, \+ y/ K$ Z# g* e* Nmetatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
position of deadwood reflflects the complementary roles played by fungi and bacteria.
. @0 f" e$ Q# D3 R9 H- [/ y8 dFungi were found to dominate the decomposition of deadwood and particularly its re
# c0 v4 x$ W5 y& Jcalcitrant fractions, while several bacterial taxa participate in N accumulation in dead
/ l4 c$ O+ `; K& t5 i' t: x  Owood 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
0 b3 g" \, s! K9 [1 E7 B9 F. k. q9 kstraints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
& a" R+ _1 Q7 Vthat 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.