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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% h/ n7 c% ]9 Y6 I( m1 J) OForests accumulate and store large amounts of carbon (C), and a sub
6 F+ r  I" Y( ]( estantial fraction of this stock is contained in deadwood. This transient pool is subject
4 R! V- ?8 F7 V5 q" Vto decomposition by deadwood-associated organisms, and in this process it contrib
utes to CO2
( l3 n! {% m; Zemissions. Although fungi and bacteria are known to colonize dead
0 l# q$ T) p' u- r) T8 ?wood, 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,
metatranscriptomics, and nutrient flflux measurements, we demonstrate that the decom
3 F7 A3 A9 D. O2 _3 f7 i0 Pposition of deadwood reflflects the complementary roles played by fungi and bacteria.
Fungi were found to dominate the decomposition of deadwood and particularly its re
calcitrant fractions, while several bacterial taxa participate in N accumulation in dead
wood 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
straints of deadwood decomposition for fungi. Both the CO2 efflflux and N accumulation
+ u4 x$ w% N$ 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.