What question did this study set out to answer?

This study aims to explore the impact of plant detritus on soil-available nitrogen and phosphorus in two forest types.

May 28, 2026Open Access

Effects of Plant Detritus Manipulation on Available Nitrogen and Phosphorus in Topsoil of Two Forest Types in Northeast China

Key Points

This study aims to explore the impact of plant detritus on soil-available nitrogen and phosphorus in two forest types.
Utilized detritus input and removal treatments (DIRTs) across six experimental conditions.
Measured soil ammonium nitrogen, nitrate nitrogen, and phosphorus monthly from May to October in Korean pine and Aspen-birch forests.
Analyzed the seasonal dynamics of available nutrients and their response to root and litter manipulations.
In Korean pine soil, NH4+-N ranged from 1.16–12.52 mg/kg, NO3−-N from 7.34–35.40 mg/kg, and AP from 9.63–31.72 mg/kg.
In Aspen-birch soil, NH4+-N ranged from 2.94–13.17 mg/kg, NO3−-N from 3.45–28.47 mg/kg, and AP from 1.77–25.60 mg/kg.
Root treatments significantly affected AN and AP more than litter treatments, with notable variations and effects on N:P ratios in different forest types.

Abstract

Plant detritus plays a pivotal role in regulating soil nutrient dynamics within forest ecosystems. Understanding short-to-medium-term responses of soil-available nitrogen (AN) and phosphorus (AP) to altered detritus inputs is important for forest nutrient management. In this study, we investigated the effects of changing detritus inputs on soil AN and AP in two representative forest types in Northeast China—Korean pine (Pinus koraiensis Siebold et Zucc.) forest (KP) and Aspen (Populus ussuriensis Kom.)−birch (Betula platyphylla Sukaczev) forest (AB). Using the detritus input and removal treatments (DIRTs) method, we established six experimental treatments and measured soil ammonium nitrogen (NH4+-N), soil nitrate nitrogen (NO3−-N), and AP contents monthly from May to October. The results showed that significant differences in NH4+-N, NO3−-N, and AP contents were observed among treatments. Under the six DIRTs, the fluctuation ranges of NH4+-N, NO3−-N, and AP contents in KP soil were 1.16–12.52 mg/kg, 7.34–35.40 mg/kg, and 9.63–31.72 mg/kg, respectively. For AB soil, the fluctuation ranges of the above three nutrients under the six DIRTs were 2.94–13.17 mg/kg, 3.45–28.47 mg/kg, and 1.77–25.60 mg/kg, respectively. Root treatments exerted stronger effects on AN and AP than litter: root exclusion generally reduced NH4+-N but increased NO3−-N and AP, with the direction and magnitude of the response to this treatment varying with month and forest type, whereas litter treatments showed no consistent trends. The soil-available N:P ratio was lower in the KP forest than in the AB forest; root exclusion significantly reduced the N:P ratio in the AB forest but had no significant effect on that in the KP forest. In terms of seasonal dynamics, the study found that AN peaked in May and AP in July. In conclusion, these findings reflect the short-to-medium-term effects of plant detritus, forest type, and month on soil-available nitrogen and phosphorus, providing scientific insights into how detritus changes alter soil nutrients in temperate forests.

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