Dataset Information

Alterations of ecosystem nitrogen status following agricultural land abandonment in the Karst Critical Zone Observatory (KCZO), Southwest China

ABSTRACT:

Background

Secondary succession after agricultural land abandonment generally affects nitrogen (N) cycle processes and ecosystem N status. However, changes in soil N availability and NO3– loss potential following secondary succession are not well understood in karst ecosystems.

Methods

In the Karst Critical Zone Observatory (KCZO) of Southwest China, croplands, shrub-grass lands, and secondary forest lands were selected to represent the three stages of secondary succession after agricultural land abandonment by using a space-for-time substitution approach. The contents and 15N natural abundance (δ15N) of leaves, soils, and different-sized aggregates at the three stages of secondary succession were analyzed. The δ15N compositions of soil organic nitrogen (SON) in aggregates and soil to plant 15N enrichment factor (EF = δ15Nleaf −δ15Nsoil), combined with soil inorganic N contents and δ15N compositions were used to indicate the alterations of soil N availability and NO3–loss potential following secondary succession.

Results

Leaf N content and SON content significantly increased following secondary succession, indicating N accumulation in the soil and plant. The δ15N values of SON also significantly decreased, mainly affected by plant δ15N composition and N mineralization. SON content in macro-aggregates and soil NH4+ content significantly increased while δ15N values of NH4+ decreased, implying increases in SON stabilization and improved soil N availability following secondary succession. Leaf δ15N values, the EF values, and the (NO3–-N)/(NH4+-N) ratio gradually decreased, indicating reduced NO3– loss following secondary succession.

Conclusions

Soil N availability improves and NO3– leaching loss reduces following secondary succession after agricultural land abandonment in the KCZO.

SUBMITTER: Liu M

PROVIDER: S-EPMC9885863 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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