Seasonality of factors controlling N mineralization rates among slope positions and aspects in cool-temperate deciduous natural forests and larch plantations

Takuo Hishi, Rieko Urakawa, Naoaki Tashiro, Yuka Maeda, Hideaki Shibata

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

This study aimed to evaluate the spatial patterns of soil nitrogen (N) transformations in relation to slope aspect and position, and to investigate the main factors controlling N transformation patterns during both the growing and dormant seasons in cool-temperate deciduous natural forests and larch plantations in eastern Hokkaido, northern Japan. Net rates of N mineralization (NRminN) and of nitrification (NRnit) in surface soils on north-facing and lower slopes were higher than those on south-facing and upper slopes, whereas the net rate of ammonium-N production (NRamm) on south-facing and upper slopes was higher than that on north-facing slopes in both the natural forests and larch plantations. Both NRminN and NRnit were higher in the growing than in the dormant season, whereas NRamm was higher in the dormant season. The soil C/N ratio, water content, soil pH and frequency of freeze-thaw cycles were important variables affecting N transformation patterns in any season. In relation to seasonality, the solar radiation index, daily temperature range and earthworm biomass were important controlling factors only during the growing season, and watershed area and soil N concentration only during the dormant season, suggesting that biological control accompanied with wet-dry events were important factors affecting N transformations during the growing season, but that run-off water and chemical controls were important determinants of spatial variation in N transformations during the dormant season.

Original languageEnglish
Pages (from-to)343-356
Number of pages14
JournalBiology and Fertility of Soils
Volume50
Issue number2
DOIs
Publication statusPublished - Sep 28 2014

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Agronomy and Crop Science
  • Soil Science

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