DOI: 10.5061/dryad.kwh70rzh3
title: Data from: Long-term drought triggers contrasting responses of foliar stable nitrogen isotopes and soil available nitrogen in a subtropical forest

description: Drought disrupts nitrogen (N) cycling by simultaneously reshaping N
 dynamics in leaves and soils, potentially limiting plant growth and
 ecosystem productivity. Understanding how drought affects these coupled
 dynamics in forests is crucial for predicting future carbon-nitrogen
 interactions amid declining global N availability. Based on a long-term
 experimental drought platform in a subtropical evergreen broad-leaved
 forest, foliar N concentration, stable N isotopes (δ15N) in two dominant
 tree species, i.e., Lithocarpus glaber and Schima superba, and four soil N
 stocks (i.e., total, ammonia, nitrate, and available N) were determined to
 assess drought-induced shifts in N cycles in subtropical forests.
 Experimental droughts significantly decreased soil N stocks, with typical
 declines in soil ammonia (14.6%) and available N (14.3%) contents,
 indicating less soil available N under water limitation. While foliar N
 concentration decreased slightly (1.5% - 2.9%), the canopy-level leaf area
 index (10.5%) and relative growth rates of the dominant species (19.0% -
 32.1%) significantly declined, indicating a reduction in plant N demand
 under droughts. Moreover, foliar δ15N was significantly enriched in both
 dominant species, with the foliar δ15N of L. glaber and S. superba
 enriching from -3.0 ± 0.2‰ to -2.1 ± 0.2‰ and from -4.5 ± 0.2‰ to -3.5 ±
 0.2‰, respectively. Synthesis: Our results show that long-term drought
 accelerates losses of soil available N due to reduced moisture, leading to
 a more open N cycle and enriched foliar δ15N in dominant species. This
 shift suggests altered plant N uptake and reduced ecosystem N retention,
 increasing the risk of N limitation under climate change in subtropical
 forests. 
description: # Data from: Long-term drought triggers contrasting responses of foliar
 stable nitrogen isotopes and soil available nitrogen in a subtropical
 forest **Authors:** Songbo Tang, Huanfa Sun, Xiaoni Xu, Fangxiu Wan,
 Erqian Cui, Yang Qiao, Ying Du, Xuhui Zhou, Jianyang Xia, Liming Yan
 **Corresponding authors:** Jianyang Xia
 ([jyxia@des.ecnu.edu.cn](mailto:jyxia@des.ecnu.edu.cn)) and Liming Yan
 ([lmyan@des.ecnu.edu.cn](mailto:lmyan@des.ecnu.edu.cn)) **File:
 data01.xlsx: Foliar nitrogen concentration and stable nitrogen isotopes**
 * **Description (Column: Description, Type)** **Plot:** Plot number,
 Integer (Experimental Drought plots: 1,2,4; Control plots: 7, 8, 9)
 **Year:** Sampling year, Integer **Month:** Sampling month, Integer
 **Treatment:** Treatment, String (Drought: Experimental Drought; CK:
 Control) **Species:** Species name, String (SS: *Schima superb*, LG:
 *Lithocarpus glaber*) **N15:** Foliar δ15N (%), Numeric **N:** Foliar N
 concentration (%), Numeric **File: data02_Ntypes.CSV: Soil nitrate
 (NO3-N), ammonia (NH4-N), and available nitrogen (AN) contents** *
 **Description (Column: Description, Type)** **Plot:** Plot number, Integer
 (Experimental Drought plots: 1,2,4; Control plots: 7, 8, 9) **Treatment:**
 Treatment, String (Drought: Experimental Drought; CK: Control) **Year:**
 Sampling year, Integer **Month:** Sampling month, Integer **NH4:** Soil
 NH4 content (NH4-N, mg/kg), Numeric **NO3:** Soil NO3 content (NO3-N,
 mg/kg), Numeric **AN:** Soil available N content (mg/kg), Numeric **File:
 data02_SM.CSV: Soil mositure (Soil_Moisture, %)** * **Description (Column:
 Description, Type)** **Year:** Sampling year, Integer **Month:** Sampling
 month, Integer **Day:** Sampling Day, Integer **Treatment:** Treatment,
 String (Drought: Experimental Drought; CK: Control) **Soil_Moisture:**
 Soil moisture (%), Numeric **File: data02_TN.xlsx: Soil total nitrogen
 contents (TN) and stable nitrogen isotope (SN15)** * **Description
 (Column: Description, Type)** **Plot:** Plot number, Integer (Experimental
 Drought plots: 1,2,4; Control plots: 7, 8, 9) **Treatment:** Treatment,
 String (Drought: Experimental Drought; CK: Control) **Year:** Sampling
 year, Integer **Month:** Sampling month, Integer **SN15:** Soil δ15N (‰),
 Numeric **TN:** Soil N content (%), Numeric **File: LAI.CSV: leaf area
 index** * **Description (Column: Description, Type, format)**
 **LAI_File:** Raw File, String **Plot:** Plot number, Integer
 (Experimental Drought plots: 1,2,4; Control plots: 3, 5, 6, 7, 8, 9)
 **Date:** Test time, String, YYYYMMDD HH:MM:SS **Time:** Test time,
 Integer, YYYYMMDD **LAI:** Leaf area index (unitless), Numeric **Note:**
 The missing values are replaced with "n/a" (not available
 because these data were not measured) **Code/Software** **File: R code.R:
 All R code for analysis and data visualization in the study** *
 **Description** R version 4.4.2 (2024-10-31 ucrt) * **Necessary packages
 (Version)** library(ggpmisc) (v0.5.6) library(ggpubr) (v0.6.0)
 library(patchwork) (v1.3.0) library(tidyverse) (v2.0.0) library(vegan)
 (v2.6-6.1) library(ggh4x) (v0.2.8) library(ggforce) (v0.4.2)
 library(multcomp) (v1.4-25) library(emmeans) (v1.10.2) library(reshape2)
 (v1.4.4) library(lmerTest) (v3.1-3)