Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (1): 102-113.DOI: 10.17521/cjpe.2021.0191

• Research Articles • Previous Articles     Next Articles

Effects of simulated drought and phosphorus addition on nitrogen mineralization in tropical lowland rain forests

Yang ZHAO1, Jun-Wei LUAN1, Yi WANG1, Huai YANG1, Shi-Rong LIU2,*()   

  1. 1Institute of Resources and Environment, International Center for Bamboo and Rattan, Key Laboratory of National Forestry and Grassland Administration/Beijing for Bamboo and Rattan Science and Technology, Beijing 100102, China
    2Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
  • Received:2021-05-19 Accepted:2021-07-13 Online:2022-01-20 Published:2022-04-13
  • Contact: Shi-Rong LIU
  • Supported by:
    Foundamental Research Funds for ICBR(1632019006);Foundamental Research Funds for ICBR(1632021023);the National Natural science Foundation of China(31930078);the National Natural science Foundation of China(31971461)

Abstract:

Aims Soil nitrogen (N) mineralization is the main process of N transformation, which determines soil N supply capacity. According to the report that the intensity and frequency of extreme hydrological events such as drought would continue to increase in the future. However, how drought impact on soil N mineralization in tropical lowland rain forests, and if this process is regulated by phosphorus (P) are less understood, given that tropical ecosystem is normally considered as P-limited. Methods Here, we employed a two-factor climate change manipulative experiment (50% throughfall reduction and P addition), which was established in 2019 in a tropical lowland rain forest in the Ganza Ridge Nature Reserve in Sanya, Hainan. The in-situ resin core method was used to study the effects of drought and P addition on soil inorganic N and N mineralization process. Important findings Our results show that: 1) Rainfall reduction significantly reduced the soil moisture at depths of 5 cm and 15 cm, but had no significant effect on soil temperature. 2) Rainfall reduction and the interactive treatment of rainfall reduction and P addition did not impact on soil inorganic N (including ammonium N and nitrate N) content in the dry season or wet season, but P addition significantly reduced soil nitrate N in the dry season, indicated that the effect of P addition on N availability was mainly reflected in the dry season rather than wet season. 3) Rainfall reduction significantly reduced the net ammonification rate and net N mineralization rate in both dry and wet seasons, however, these processes did not respond to P addition or their interaction. 4) Soil moisture positively correlated with the soil net ammonification rate and the net N mineralization rate. Meanwhile, rainfall reduction significantly affected the relationship between the soil net ammonification rate and the ammonium N content, where when the ammonium N was comparable, the net ammonification rate dropped faster under the impact of drought. This indicated that the change of soil moisture was the main factor that affected the soil N mineralization of the study plots. Collectively, our results demonstrated that precipitation changes had an important impact on soil N mineralization in tropical lowland rain forests, but short-term P addition had no significant effect, rainfall reduction and P addition had no interactive effect on the soil N mineralization processes.

Key words: tropical lowland rain forest, drought, phosphorus addition, nitrogen cycle, inorganic nitrogen, soil nitrogen mineralization