Effects of soil warming on fine root growth and morphology of Castanopsis kawakamii in mid-subtropical forests

doi:10.17521/cjpe.2024.0298

Abstract

Abstract:

Aims This study aims to reveal the effects of soil warming on the fine root growth and morphological traits of subtropical evergreen broadleaf forests in China.

Methods At the Fujian Sanming Forest Ecosystem National Observation and Research Station, we used an in-situsoil warming experiment and cooperated with the method of in-growth core in a Castanopsis kawakamii forest to explore fine root biomass growth and morphological traits during the rainy season (May) and dry season (November). In this study, we sorted fine roots into absorption roots (diameter < 1 mm) and transport roots (diameter 1-2 mm).

Important findings Compared with the control, during the rainy season, soil warming treatment significantly reduced the biomass of absorptive roots by 41.2%, contrasting no changes of transport roots. Soil warming also did not alter the diameter and length of absorptive and transport roots, but specific root length (SRL) and specific root area (SRA) were significantly reduced by 53.2% and 42.9%, respectively, and root tissue density (RTD) was significantly increased by 28.8% in absorption roots. During the dry season, soil warming significantly increased the biomass of absorptive and transportive roots, as well as their root length (increased by 38.5% and 33.5%, respectively). However, the diameter, SRL, SRA, and RTD of absorptive and transport roots did not alter in soil warming treatment during the dry season. These results suggest that fine roots of Castanopsis kawakamii in mid-subtropical forests exhibited higher plasticity to cope with climate changes, such as adjusting absorptive root traits to alleviate the effect of soil warming on the resource absorption and growth during the rainy season, and increasing root length to expand resource absorption space during the dry season. This study provides a scientific basis for understanding the ecological adaptation and resource acquisition strategies of functionally distinct fine roots in subtropical forests under global warming.

Key words: soil warming, mid-subtropical, natural forest, fine root biomass growth, morphological trait, functional trait

LIANG Tian-Hao, WU Fan, HUANG Jin-Xue, JING Chen-Hong, FU He-Jing, YANG Zhi-Jie, XIONG De-Cheng. Effects of soil warming on fine root growth and morphology of Castanopsis kawakamii in mid-subtropical forests[J]. Chin J Plant Ecol, 2026, 50(1): 94-106.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2024.0298

https://www.plant-ecology.com/EN/Y2026/V50/I1/94

Figures/Tables 11

Table 1 Stand characteristics of Castanopsis kawakamii natural forest

林分 Stand	海拔 Altitude (m)	坡度 Slope (°)	林分密度 Stand density (plant·hm^-2)	植物组成 Plant composition	平均树高 Mean tree height (m)	平均胸径 Mean diameter at breast height (cm)
格氏栲天然林 Castanopsis kawakamii natural forest	240	30	3 285	格氏栲、米槠、木荷、狗骨柴、百两金和毛冬青等 Castanopsis kawakamii, Castanopsis carlesii, Schima superba, Diplospora dubia, Ardisia crispa, Ilex pubescens, et al.	35.1	57.7

Table 2 Effects of warming on soil physical and chemical properties in Castanopsis kawakamii natural forest

处理 Treatment	pH	总碳含量 Total carbon content (g·kg^-1)	总氮含量 Total nitrogen content (g·kg^-1)	矿质氮含量 Mineral nitrogen content (mg·kg^-1)	NH₄⁺-N含量 NH₄⁺-N content (mg·kg^-1)	NO₃^--N含量 NO₃^--N content (mg·kg^-1)
CK	4.17 ± 0.04^a	24.55 ± 0.75^a	1.67 ± 0.06^a	8.13 ± 0.66^a	6.21 ± 0.37^a	1.92 ± 0.29^a
W	4.24 ± 0.04^a	23.23 ± 1.06^a	1.44 ± 0.08^a	5.20 ± 0.32^b	4.77 ± 0.28^b	0.43 ± 0.04^b

Fig. 1 Effects of warming on soil temperature and moisture of Castanopsis kawakamii natural forest. CK, control treatment; M, month; W, warming treatment. *, p < 0.05; **, p < 0.01; ns, p > 0.05.

Table 3 Mixed linear model analysis on the effects of season and warming on the growth and morphological traits of fine roots in Castanopsis kawakamii natural forest

指标 Index	细根径级 Diameter class of fine root (mm)	S		W		S × W
指标 Index	细根径级 Diameter class of fine root (mm)	F	p	F	p	F	p
生长量 Fine root growth (m²·g^-1)	0-1	76.517	0	39.665	0.003	31.196	0.001
	1-2	69.950	0	16.255	0.016	9.759	0.014
	0-2	67.941	0.001	0	0	0	0
根长 Root length (cm)	0-1	0.506	0.497	5.248	0.084	5.481	0.047
根长 Root length (cm)	1-2	21.536	0.002	0.166	0.694	29.072	0.001
直径 Diameter (mm)	0-1	8.198	0.021	3.699	0.127	0.006	0.940
直径 Diameter (mm)	1-2	3.045	0.119	0.008	0.935	0.607	0.458
比根长 Specific root length (m·g^-1)	0-1	0.204	0.664	4.612	0.064	9.264	0.016
比根长 Specific root length (m·g^-1)	1-2	2.135	0.182	1.817	0.249	0.767	0.407
比根表面积 Specific root surface area (cm²·g^-1)	0-1	2.146	0.181	5.143	0.053	12.546	0.008
比根表面积 Specific root surface area (cm²·g^-1)	1-2	0.008	0.933	3.062	0.155	0.396	0.547
根组织密度 Root tissue density (g·cm^-3)	0-1	3.038	0.120	2.429	0.158	5.534	0.047
根组织密度 Root tissue density (g·cm^-3)	1-2	3.973	0.081	5.850	0.042	0.874	0.377

Table 4 Mixed linear model analysis on the effects of warming and diameter class on the growth and morphological traits of fine roots in Castanopsis kawakamii natural forest

指标 Index	因子 Factor	雨季 Rainy season		旱季 Dry season
指标 Index	因子 Factor	F	p	F	p
细根生长量 Fine root growth (m²·g^-1)	W	0.111	0.756	37.335	0.004
	D	0.089	0.774	17.911	0.003
	W × D	1.603	0.241	15.452	0.004
根长 Root length (cm)	W	6.106	0.039	28.365	0.001
	D	38.293	0	3.088	0.117
	W × D	2.182	0.178	0.205	0.663
直径 Diameter (mm)	W	0.914	0.393	0.205	0.674
	D	33.896	0	192.733	0
	W × D	0.081	0.783	0.922	0.365
比根长 Specific root length (m·g^-1)	W	6.804	0.060	0.173	0.688
	D	67.820	0	174.479	0
	W × D	12.455	0.008	2.801	0.133
比根表面积 Specific root surface area (cm²·g^-1)	W	13.434	0.021	0.244	0.634
	D	50.758	0	62.377	0
	W × D	7.886	0.023	1.816	0.215
根组织密度 Root tissue density (g·cm^-3)	W	8.001	0.022	0.076	0.797
	D	8.802	0.018	1.028	0.340
	W × D	0.042	0.843	0.926	0.364

Fig. 2 Effect of warming on fine root growth of Castanopsis kawakamii natural forest (mean ± SE). CK, control treatment; W, warming treatment. Different uppercase letters indicate significant differences between treatments of the same diameter class (p < 0.05), and different lowercase letters indicate significant differences between diameter classes of the same treatment (p < 0.05).

Fig. 3 Effect of warming on fine root diameter of Castanopsis kawakamii natural forest (mean ± SE). CK, control treatment; W, warming treatment. Different uppercase letters indicate significant differences between treatments of the same diameter class (p < 0.05), and different lowercase letters indicate significant differences between diameter classes of the same treatment (p < 0.05).

Fig. 4 Effect of warming on fine root length of Castanopsis kawakamii natural forest (mean ± SE). CK, control treatment; W, warming treatment. Different uppercase letters indicate significant differences between treatments of the same diameter class (p < 0.05), and different lowercase letters indicate significant differences between diameter classes of the same treatment (p < 0.05).

Fig. 5 Effect of warming on specific root length, specific root surface area and root tissue density of Castanopsis kawakamii natural forest (mean ± SE). CK, control treatment; W, warming treatment. Different uppercase letters indicate significant differences between treatments of the same diameter class (p < 0.05), and different lowercase letters indicate significant differences between diameter classes of the same treatment (p < 0.05).

Fig. 6 Partial least squares path modeling (PLS-PM) analysis of the possible direct and indirect pathways through which rainy season warming affected fine root growth and morphology. Solid lines indicate significant path, dash lines indicate insignificant path. Numbers listed by arrows are the standardized path coefficients. *, p < 0.05; **, p < 0.01. C, carbon; N, nitrogen; RD, root diameter; RL, root length; RTD, root tissue density; SRA, specific root area; SRL, specific root length. GOF, goodness of fit.

Fig. 7 Partial least squares path modeling (PLS-PM) analysis of the possible direct and indirect pathways through which dry season warming affected fine root growth and morphology. Solid lines indicate significant path, dash lines indicate insignificant path. Numbers listed by arrows are the standardized path coefficients. *, p < 0.05; **, p < 0.01. C, carbon; N, nitrogen; RD, root diameter; RL, root length; RTD, root tissue density; SRA, specific root area; SRL, specific root length. GOF, goodness of fit.

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