EFFECTS OF LIGHT ON SEED GERMINATION AND SEEDLING ESTABLISHMENT OF A TROPICAL RAINFOREST CANOPY TREE, POMETIA TOMENTOSA

doi:10.17521/cjpe.2007.0130

Abstract

Abstract:

Aims Pometia tomentosa is the major dominant species in the tropical seasonal rain forests of Xishuangbanna, Southwest China. It is listed in the rare and endangered species in China. Research on seed and seedling ecology of P. tomentosa may provide information for rare and endangered species conservation and forest restoration.

Methods Shade house and forest experiments were designed to investigate light effects on seed germination and seedling establishment of P. tomentosa. Seedling growth, biomass allocation and physiological properties of P. tomentosa were examined in neutral-density shade houses, which were used to mirror different light levels in centers of forest gaps, at edges of forest gaps and forest understory.

Important findings Results showed that final seed germinations in all treatments were greater than 95% and occurred within six days. Seedlings in 30% light treatment had the highest root mass ratio (RMR) and stem mass ratio (SMR). However, seedlings in 10% and 3.5% light treatments had the highest leaf mass ratio (LMR). Seedlings grown in low light environments (such as 10% and 3.5% light treatments) had a higher leaf area ratio (LAR) than those in high light (30% light treatment). Seedlings in 30% light treatment had the highest maximum photosynthetic rate (P_n_max), dark respiration (R_d) and light saturation point (I_sat), but the compensation point (I_comp) was not significantly different among the three light treatments. Seedlings of P. tomentosa were able to grow slowly and survive for a long time; therefore, it is a shade tolerant species. Also, seedlings of shade houses showed increased RGR_M and RGR_H in high light comparing with low light. It is concluded that gaps in the forest canopy are probably necessary for successful regeneration of P. tomentosa. Soil moisture also may affect the habitat selection of P. tomentosa seedlings.

Key words: seedling growth, relative growth rate, shade tolerance, Xishuangbanna

YU Yang, CAO Min, ZHENG Li, SHENG Cai-Yu. EFFECTS OF LIGHT ON SEED GERMINATION AND SEEDLING ESTABLISHMENT OF A TROPICAL RAINFOREST CANOPY TREE, POMETIA TOMENTOSA[J]. Chin J Plant Ecol, 2007, 31(6): 1028-1036.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2007.0130

https://www.plant-ecology.com/EN/Y2007/V31/I6/1028

Figures/Tables 7

References 46

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变量 Variable	计算方法 Calculation	缩写 Abbreviation	单位 Units
质量相对生长速率Relative mass growth rate^*	(ln W₂ - ln W₁)/(T₂-T₁)	RGR_M	g·g^-1·mol^-1
高度相对生长速率Relative height growth rate^*	(ln H₂ - ln H₁) / (T₂-T₁)	RGR_H	cm·cm^-1·mol^-1
叶面积比Leaf area ratio	Total leaf area / Total seedling dry weight	LAR	cm²·g^-1
叶重比Leaf mass ratio	Leaf dry weight / Total seedling dry weight	LMR	g·g^-1
根重比Root mass ratio	Root dry weight / Total seedling dry weight	RMR	g·g^-1
茎重比Stem mass ratio	Stem dry weight / Total seedling dry weight	SMR	g·g^-1
比叶重 Specific leaf weight	Leaf dry weight / Leaf area	SLW	g·cm^-2

变量 Variable	计算方法 Calculation	缩写 Abbreviation	单位 Units
质量相对生长速率Relative mass growth rate^*	(ln W₂ - ln W₁)/(T₂-T₁)	RGR_M	g·g^-1·mol^-1
高度相对生长速率Relative height growth rate^*	(ln H₂ - ln H₁) / (T₂-T₁)	RGR_H	cm·cm^-1·mol^-1
叶面积比Leaf area ratio	Total leaf area / Total seedling dry weight	LAR	cm²·g^-1
叶重比Leaf mass ratio	Leaf dry weight / Total seedling dry weight	LMR	g·g^-1
根重比Root mass ratio	Root dry weight / Total seedling dry weight	RMR	g·g^-1
茎重比Stem mass ratio	Stem dry weight / Total seedling dry weight	SMR	g·g^-1
比叶重 Specific leaf weight	Leaf dry weight / Leaf area	SLW	g·cm^-2

种子萌发特征 Seed germination characteristics	遮荫试验 Shade house experiment			森林试验 Forest experiment
种子萌发特征 Seed germination characteristics	30% light	10% light	3.5% light	CG	EG	UF
萌发率Final germination (%)	0.99^a (0.01)	0.96^a (0.02)	0.97^a (0.02)	0.96^a (0.02)	0.97^a (0.01)	0.95^a (0.02)
平均萌发周期 Mean period of final germination (d)	5.22^a (0.63)	4.95^a (0.46)	4.98^a (0.39)	5.10^a (0.31)	4.98^a (0.41)	4.96^a (0.55)

种子萌发特征 Seed germination characteristics	遮荫试验 Shade house experiment			森林试验 Forest experiment
种子萌发特征 Seed germination characteristics	30% light	10% light	3.5% light	CG	EG	UF
萌发率Final germination (%)	0.99^a (0.01)	0.96^a (0.02)	0.97^a (0.02)	0.96^a (0.02)	0.97^a (0.01)	0.95^a (0.02)
平均萌发周期 Mean period of final germination (d)	5.22^a (0.63)	4.95^a (0.46)	4.98^a (0.39)	5.10^a (0.31)	4.98^a (0.41)	4.96^a (0.55)

	遮荫试验Shade house experiment
	30% light	10% light	3.5% light
a. 幼苗大小参数Size parameters
叶面积 Total leaf area (cm²)	10 885^a (1044)	4706^b (256)	867^c (97)
幼苗高度增量 Seedling height increment (cm)	127.6^a (18.5)	86.9^b (17.1)	20.5^c (3.9)
叶片数增量 Net leaf gain	14.6^a (1.8)	10.8^b (1.7)	7.5^c (1.4)
b. 生物量分配Biomass allocation
总干重 Total dry mass (g)	573.7^a (75.7)	149.3^b (18.6)	41.8^c (8.4)
质量相对生长速率 Relative mass growth rate RGR_M (g·g^-1·mol^-1)	1.07^a (0.09)	0.79^b (0.07)	0.45^c (0.08)
高度相对生长速率 Relative height growth rate RGR_H (cm·cm^-1·mol^-1)	0.24^a (0.02)	0.18^b (0.01)	0.09^c (0.02)
根重比 Root mass ratio RMR (g·g^-1)	0.25^a (0.01)	0.11^c (0.02)	0.13^c (0.01)
茎重比 Stem mass ratio SMR (g·g^-1)	0.53^a (0.03)	0.43^b (0.02)	0.42^b (0.03)
叶重比 Leaf mass ratio LMR (g·g^-1)	0.23^b (0.02)	0.47^a (0.05)	0.46^a (0.03)
叶面积比 Leaf area ratio LAR (cm²·g^-1)	79.7^c (4.6)	120.2^b (5.8)	145.7^a (7.4)
c. 幼苗存活率 Seedling survival (%)	77.5^a (1.3)	74^a (1.5)	71.5^a (1.8)