水保所知识产出(1956---)知识库

Biodegradation of dissolved organic matter (DOM) plays a key role in regulating both production of
greenhouse gases and accumulation and stabilisation of soil organic matter (SOM). However, the mecha-
nisms by which natural vegetation restoration affects the extent, rate, and temperature sensitivity of DOM
biodegradation are poorly understood. Elucidating these mechanisms is important for SOM management,
especially in light of future climate warming scenarios. In this study, a laboratory DOM solution incu-
bation experiment was conducted to comprehensively investigate the effects of temperature and natural
vegetation restoration spanning a period of 160 y on DOM biodegradation in the Loess Plateau, China. The
results indicated that dissolved organic C (DOC) biodegradation significantly decreased with vegetation
restoration after an incubation period of 60 d. Further, biodegradation of dissolved organic N (DON) and
dissolved organic P (DOP) significantly decreased after farmland abandonment. Specifically, the lowest
values were observed in pioneer ( Populus davidiana ) and mingled ( Populus davidiana and Quercus liaotun-
gensis ) forests. Generally, an increase in temperature significantly promoted the biodegradation of DOC,
DON, and DOP by enhancing the microbial utilisation efficiencies of recalcitrant humic substrates (i.e.,
low-molecular-weight humic materials). Our results suggest that DOM biodegradability and its tempera-
ture sensitivity were regulated by DOM substrate quality (i.e, recalcitrant humic materials), and microbial
properties (i.e., gram-negative bacterial and fungal PLFA, enzyme activities). Additionally, our results sug-
gest that climax forest communities ( Quercus liaotungensis ) played a vital role in reducing DOC and DOP
losses. This could be attributed to the low Q10 of the DOC and DOP biodegradation rates.