Spatial variation in soil physical properties and effects on soil NO3– production on forest hillslopes

作者：Tomoki Oda, Megumi Kuroiwa, Naoya Fujime, Kazuo Isobe, Naoya Masaoka, Kazumichi Fujii, Hiroto Toda, Nobuhito Ohte · 年份：2020 · DOI：10.5194/egusphere-egu2020-6463 · 研究领域：Agriculture, Soil, Plant Science、Energy, Environment, Agriculture Analysis、Soil and Water Nutrient Dynamics

&lt;p&gt;Ammonium (NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;) and nitrate (NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8211;&lt;/sup&gt;) concentrations and production rates in forest soil vary by hillslope position due to variation in ammonia-oxidizing microorganism concentrations, soil chemistry, and surface soil moisture. These spatial distributions have a significant effect on nutrient cycles and streamwater chemistry. Soil moisture conditions significantly restrict microbial activity, influencing the spatial distribution of NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8211;&lt;/sup&gt; concentrations on forest hillslopes. However, studies linking forest hydrological processes to nitrogen cycling are limited. Therefore, we investigated the determinants of spatial variation in soil moisture and evaluated the effects of soil moisture fluctuations on spatial variation in NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8211;&lt;/sup&gt; concentration and production rate.&lt;/p&gt;&lt;p&gt;The study sites were the Fukuroyamasawa Experimental Watershed (FEW) and Oyasan Experimental Watershed (OEW) in Japan. The two have similar topographies, climates, and tree species. In each watershed, a 100 m transect was set up from the ridge to the base of the slope, and soil moisture sensors were installed at soil depths of 10...