水保所知识产出(1956---)知识库

The influence of plant secondary succession on soil enzyme activities has been increasingly recognized recently.
However, the characteristics of specific enzyme activities and temperature sensitivity (Q 10 ) in the rhizosphere
remain elusive. We collected rhizosphere and bulk soil samples from a secondary successional series (0, 7, 12, 17,
22, and 32 years after farmland abandonment, and a natural grassland reference) in a typical semi-arid eco-
systems on the Loess Plateau of China. The potential activity of soil enzymes, including β-1,4-glucosidase (BG),
β-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (AP), was
assayed at 37, 20 and 4 ◦ C and expressed as activity per unit of soil organic carbon (specific enzyme activity). Q 10
values were calculated at 20–37 ◦ C and 4–20 ◦ C, respectively. The specific enzyme activities of BG, NAG, LAP and
AP in bulk soil increased to a maximum at the 17-year site and then significantly decreased in older grasslands. In
the rhizosphere, specific enzyme activities increased and then decreased along the successional gradient with
significantly higher value at the 7-year site and the 17-year site. The Q 10 values of BG activity in bulk soil and the
four enzyme’s activities in rhizosphere soil were changed significantly along the successional gradients. In
general, the Q 10 values at the two temperature ranges differed in bulk soil, but not in the rhizosphere soil. Along
the plant successional gradient, the rhizosphere effects of specific enzyme activities gradually changed to
negative values in the oldest sites. Our results indicate that plant secondary succession had different impacts on
the enzyme activity and characteristics in the rhizosphere and bulk soil, and highlights the importance of
temperature sensitivity and rhizosphere effects of enzyme activity along plant secondary successional gradients.