Effects of phosphorus addition on functional traits across seedlings and saplings in a tropical cloud forest

doi:10.17521/cjpe.2025.0361

Abstract

Abstract:

Aims Plant functional traits reflect key strategies of resource acquisition, utilization and conservation, and play a critical role in shaping plant responses to environmental change. Soil phosphorus (P) content is a major limiting nutrient in tropical forest ecosystems, and changes in its availability may alter plant resource-use strategies at different growth stages. This study aimed to examine the responses of functional traits and their interrelationships to P addition in seedlings and saplings in a tropical cloud forest.

Methods Seedlings and saplings from the Bawangling area of National Park of Hainan Tropical Rainforest were selected as this study materials. Three P addition treatments (low, medium and high) were established. The leaf thickness (LT), leaf dry matter content (LDMC), specific leaf area (SLA), leaf nitrogen contents (LN), leaf phosphorus contents (LP) and branch density (BD) of the plants were measured. Functional traits responses and trait-trait relationships under different P addition levels were analyzed for both seedlings and saplings.

Important findings (1) The growth stage of plants and P concentration significantly influenced the functional traits of plants. Under the CK treatment, compared with saplings, seedlings exhibited a more resource acquisitive strategy. With increasing P concentration, seedlings showed higher SLA, LP and low LT, LDMC, whereas saplings exhibited no significant trait changes. The two ends of the principal component 1 (PC1) axis represented the resource-acquisitive and resource-conservative strategies, respectively, with seedlings positioned toward the acquisitive end relative to saplings. (2) BD-LDMC, SLA-LN, SLA-LP, and LN-LP of seedlings and saplings were significantly positively correlated, and BD-SLA, LDMC-SLA, LDMC-LN, LDMC-LP, and SLA-LT were significantly negatively correlated, indicating that there were generally synergies and trade-offs among plant functional traits. Under the CK treatment, the slopes of BD-LDMC, BD-SLA, LDMC-LN and SLA-LN were not significantly different between seedlings and saplings, while the slopes of LDMC-LP, SLA-LP and LN-LP were significantly different between seedlings and saplings, which was opposite under P addition treatment. This indicated that P addition changed the nutrient allocation strategy between seedlings and saplings. In the low and medium P concentration conditions, the seedlings tended to invest in resource acquisition-related structures, presenting an acquisitive strategy; while in the low P condition, the saplings showed a limited resource acquisitive strategy adjustment, and their response to P addition was relatively conservative. In conclusion, responses to P addition concentrations vary between growth stages in tropical cloud forest plants. These findings improve our understanding of plant resource-use strategies and forest regeneration dynamics under increasing atmospheric P deposition.

Key words: phosphorus addition, growth stage, functional trait, trait-trait relationship, tropical cloud forest

LIN Lin-Lin, XIAO Jin-Xiang, HUANG Shen-Shen, ZHAO Yang-Mei, ZHANG De-Xu, CHENG Yi-Kang, LONG Wen-Xing. Effects of phosphorus addition on functional traits across seedlings and saplings in a tropical cloud forest[J]. Chin J Plant Ecol, 2026, 50(4): 917-928.

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Figures/Tables 6

References 66

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固定效应 Fixed effect	BD		LT		SLA		LDMC		LN		LP
固定效应 Fixed effect	F	p	F	p	F	p	F	p	F	p	F	p
磷浓度 Phosphorus concentration (P)	2.38	0.07	3.30	0.02	11.52	<0.01	6.27	<0.01	0.38	0.77	38.02	<0.01
生长阶段 Growth stage (G)	20.61	<0.01	28.27	<0.01	48.73	<0.01	7.02	<0.01	0.23	0.63	10.15	<0.01
P × G	0.53	0.66	4.43	<0.01	3.22	0.02	0.60	0.61	2.58	<0.05	0.40	0.75

固定效应 Fixed effect	BD		LT		SLA		LDMC		LN		LP
固定效应 Fixed effect	F	p	F	p	F	p	F	p	F	p	F	p
磷浓度 Phosphorus concentration (P)	2.38	0.07	3.30	0.02	11.52	<0.01	6.27	<0.01	0.38	0.77	38.02	<0.01
生长阶段 Growth stage (G)	20.61	<0.01	28.27	<0.01	48.73	<0.01	7.02	<0.01	0.23	0.63	10.15	<0.01
P × G	0.53	0.66	4.43	<0.01	3.22	0.02	0.60	0.61	2.58	<0.05	0.40	0.75

Y	X	磷浓度 Phosphorus concentration	幼苗 Seeding		幼树 Sapling		Y	X	磷浓度 Phosphorus concentration	幼苗 Seeding		幼树 Sapling
Y	X	磷浓度 Phosphorus concentration	p	斜率 Slope	p	斜率 Slope	Y	X	磷浓度 Phosphorus concentration	p	斜率 Slope	p	斜率 Slope
BD	LDMC	对照 CK	0.16	1.15^Aa	<0.01	1.02^Aa	LDMC	LP	对照 CK	0.09	-0.34^Aa	<0.01	-0.58^Bab
		低磷 LoP	<0.01	1.55^Aa	<0.01	0.91^Ba			低磷 LoP	0.01	-0.56^Ab	<0.01	-0.66^Ab
		中磷 MP	<0.01	1.54^Aa	<0.01	1.09^Ba			中磷 MP	0.03	-0.61^Ab	<0.01	-0.49^Aab
		高磷 HP	<0.01	1.53^Aa	<0.01	0.96^Ba			高磷 HP	0.01	-0.33^Aa	0.03	-0.41^Aa
BD	SLA	对照 CK	0.22	-0.97^Aa	0.02	-0.71^Aab	SLA	LT	对照 CK	<0.01	-1.22^Aa	<0.01	-1.24^Aa
		低磷 LoP	<0.01	-0.95^Ba	<0.01	-0.57^Aa			低磷 LoP	0.01	-1.63^Aa	<0.01	-1.70^Ab
		中磷 MP	0.03	-1.41^Bb	<0.01	-0.80^Ab			中磷 MP	<0.01	-1.35^Aa	<0.01	-1.28^Aab
		高磷 HP	0.01	-1.24^Bab	0.03	-0.73^Aab			高磷 HP	<0.01	-1.18^Aa	<0.01	-1.24^Aab
BD	LT	对照 CK	0.22	-1.25^Ba	0.47	0.88^Aa	SLA	LN	对照 CK	<0.01	0.78^Aa	<0.01	0.89^Ab
		低磷 LoP	0.26	-1.64^Bab	0.51	0.97^Aa			低磷 LoP	0.01	0.97^Aa	<0.01	1.35^Aa
		中磷 MP	0.40	-1.77^Bb	0.99	1.02^Aa			中磷 MP	0.01	1.00^Aa	<0.01	0.93^Ab
		高磷 HP	0.56	-1.42^Bab	0.88	-0.91^Aa			高磷 HP	<0.01	0.75^Ba	<0.01	1.14^Aab
BD	LN	对照 CK	0.24	-0.70^Aa	0.09	-0.63^Aa	SLA	LP	对照 CK	0.07	0.44^Bb	<0.01	0.86^Aab
		低磷 LoP	0.36	-1.01^Aab	<0.01	-0.70^Aa			低磷 LoP	0.03	0.81^Aa	0.02	1.06^Aa
		中磷 MP	0.06	-1.36^Bb	<0.01	-0.77^Aa			中磷 MP	0.01	0.57^Aab	<0.01	0.66^Abc
		高磷 HP	0.02	-0.93^Aab	0.06	-0.78^Aa			高磷 HP	0.02	0.37^Ab	<0.01	0.56^Ac
BD	LP	对照 CK	0.82	0.37^Aa	0.09	-0.60^Bb	LT	LN	对照 CK	0.33	-0.64^Aa	<0.01	-0.70^Aa
		低磷 LoP	0.11	-0.82^Ab	<0.01	-0.55^Aab			低磷 LoP	0.18	-0.74^Aa	0.11	-0.74^Aa
		中磷 MP	0.03	-0.78^Ab	<0.01	-0.55^Aab			中磷 MP	0.78	0.89^Aa	<0.05	-0.76^Aa
		高磷 HP	0.24	-0.46^Aa	0.44	-0.38^Aa			高磷 HP	0.86	-0.76^Aa	0.02	-0.88^Aa
LDMC	SLA	对照 CK	<0.01	-0.84^Ab	<0.01	-0.69^Aa	LT	LP	对照 CK	0.14	-0.37^Aa	0.02	-0.68^Bb
		低磷 LoP	<0.01	-0.63^Aa	<0.01	-0.63^Aa			低磷 LoP	0.46	-0.61^Ab	0.81	-0.58^Aab
		中磷 MP	<0.01	-0.87^Ab	<0.01	-0.73^Aa			中磷 MP	0.83	-0.51^Aab	0.17	-0.54^Aab
		高磷 HP	<0.01	-0.81^Aab	<0.01	-0.76^Aa			高磷 HP	0.46	0.37^Aab	0.17	-0.43^Aa
LDMC	LT	对照 CK	0.39	-1.03^Aa	0.54	-0.86^Aa	LN	LP	对照 CK	0.01	0.57^Bb	<0.01	0.97^Aa
		低磷 LoP	0.76	-1.03^Aa	0.43	1.07^Aa			低磷 LoP	<0.01	0.83^Aa	<0.01	0.79^Ab
		中磷 MP	0.52	-1.17^Aa	0.28	-0.93^Aa			中磷 MP	<0.01	0.57^Ab	<0.01	0.71^Ab
		高磷 HP	0.78	-0.96^Aa	0.70	-0.94^Aa			高磷 HP	<0.01	0.49^Ab	<0.01	0.49^Ac
LDMC	LN	对照 CK	<0.01	-0.60^Aa	<0.01	-0.60^Aa
		低磷 LoP	0.01	-0.67^Aa	<0.01	-0.83^Ab
		中磷 MP	0.01	-1.06^Bb	<0.01	-0.69^Aab
		高磷 HP	<0.01	-0.66^Aa	<0.01	-0.85^Aab

Y	X	磷浓度 Phosphorus concentration	幼苗 Seeding		幼树 Sapling		Y	X	磷浓度 Phosphorus concentration	幼苗 Seeding		幼树 Sapling
Y	X	磷浓度 Phosphorus concentration	p	斜率 Slope	p	斜率 Slope	Y	X	磷浓度 Phosphorus concentration	p	斜率 Slope	p	斜率 Slope
BD	LDMC	对照 CK	0.16	1.15^Aa	<0.01	1.02^Aa	LDMC	LP	对照 CK	0.09	-0.34^Aa	<0.01	-0.58^Bab
		低磷 LoP	<0.01	1.55^Aa	<0.01	0.91^Ba			低磷 LoP	0.01	-0.56^Ab	<0.01	-0.66^Ab
		中磷 MP	<0.01	1.54^Aa	<0.01	1.09^Ba			中磷 MP	0.03	-0.61^Ab	<0.01	-0.49^Aab
		高磷 HP	<0.01	1.53^Aa	<0.01	0.96^Ba			高磷 HP	0.01	-0.33^Aa	0.03	-0.41^Aa
BD	SLA	对照 CK	0.22	-0.97^Aa	0.02	-0.71^Aab	SLA	LT	对照 CK	<0.01	-1.22^Aa	<0.01	-1.24^Aa
		低磷 LoP	<0.01	-0.95^Ba	<0.01	-0.57^Aa			低磷 LoP	0.01	-1.63^Aa	<0.01	-1.70^Ab
		中磷 MP	0.03	-1.41^Bb	<0.01	-0.80^Ab			中磷 MP	<0.01	-1.35^Aa	<0.01	-1.28^Aab
		高磷 HP	0.01	-1.24^Bab	0.03	-0.73^Aab			高磷 HP	<0.01	-1.18^Aa	<0.01	-1.24^Aab
BD	LT	对照 CK	0.22	-1.25^Ba	0.47	0.88^Aa	SLA	LN	对照 CK	<0.01	0.78^Aa	<0.01	0.89^Ab
		低磷 LoP	0.26	-1.64^Bab	0.51	0.97^Aa			低磷 LoP	0.01	0.97^Aa	<0.01	1.35^Aa
		中磷 MP	0.40	-1.77^Bb	0.99	1.02^Aa			中磷 MP	0.01	1.00^Aa	<0.01	0.93^Ab
		高磷 HP	0.56	-1.42^Bab	0.88	-0.91^Aa			高磷 HP	<0.01	0.75^Ba	<0.01	1.14^Aab
BD	LN	对照 CK	0.24	-0.70^Aa	0.09	-0.63^Aa	SLA	LP	对照 CK	0.07	0.44^Bb	<0.01	0.86^Aab
		低磷 LoP	0.36	-1.01^Aab	<0.01	-0.70^Aa			低磷 LoP	0.03	0.81^Aa	0.02	1.06^Aa
		中磷 MP	0.06	-1.36^Bb	<0.01	-0.77^Aa			中磷 MP	0.01	0.57^Aab	<0.01	0.66^Abc
		高磷 HP	0.02	-0.93^Aab	0.06	-0.78^Aa			高磷 HP	0.02	0.37^Ab	<0.01	0.56^Ac
BD	LP	对照 CK	0.82	0.37^Aa	0.09	-0.60^Bb	LT	LN	对照 CK	0.33	-0.64^Aa	<0.01	-0.70^Aa
		低磷 LoP	0.11	-0.82^Ab	<0.01	-0.55^Aab			低磷 LoP	0.18	-0.74^Aa	0.11	-0.74^Aa
		中磷 MP	0.03	-0.78^Ab	<0.01	-0.55^Aab			中磷 MP	0.78	0.89^Aa	<0.05	-0.76^Aa
		高磷 HP	0.24	-0.46^Aa	0.44	-0.38^Aa			高磷 HP	0.86	-0.76^Aa	0.02	-0.88^Aa
LDMC	SLA	对照 CK	<0.01	-0.84^Ab	<0.01	-0.69^Aa	LT	LP	对照 CK	0.14	-0.37^Aa	0.02	-0.68^Bb
		低磷 LoP	<0.01	-0.63^Aa	<0.01	-0.63^Aa			低磷 LoP	0.46	-0.61^Ab	0.81	-0.58^Aab
		中磷 MP	<0.01	-0.87^Ab	<0.01	-0.73^Aa			中磷 MP	0.83	-0.51^Aab	0.17	-0.54^Aab
		高磷 HP	<0.01	-0.81^Aab	<0.01	-0.76^Aa			高磷 HP	0.46	0.37^Aab	0.17	-0.43^Aa
LDMC	LT	对照 CK	0.39	-1.03^Aa	0.54	-0.86^Aa	LN	LP	对照 CK	0.01	0.57^Bb	<0.01	0.97^Aa
		低磷 LoP	0.76	-1.03^Aa	0.43	1.07^Aa			低磷 LoP	<0.01	0.83^Aa	<0.01	0.79^Ab
		中磷 MP	0.52	-1.17^Aa	0.28	-0.93^Aa			中磷 MP	<0.01	0.57^Ab	<0.01	0.71^Ab
		高磷 HP	0.78	-0.96^Aa	0.70	-0.94^Aa			高磷 HP	<0.01	0.49^Ab	<0.01	0.49^Ac
LDMC	LN	对照 CK	<0.01	-0.60^Aa	<0.01	-0.60^Aa
		低磷 LoP	0.01	-0.67^Aa	<0.01	-0.83^Ab
		中磷 MP	0.01	-1.06^Bb	<0.01	-0.69^Aab
		高磷 HP	<0.01	-0.66^Aa	<0.01	-0.85^Aab