光对热带雨林冠层树种绒毛番龙眼种子萌发及其幼苗早期建立的影响

doi:10.17521/cjpe.2007.0130

摘要/Abstract

摘要：

绒毛番龙眼(Pometia tomentosa)为西双版纳热带季节雨林标志树种,被列为中国珍稀濒危植物。对其开展种子及幼苗生态学研究可为珍稀濒危树种的保护及当地森林恢复提供科学依据。试验采用遮荫试验和野外试验相结合的方法,研究光对绒毛番龙眼种子萌发及幼苗早期建立的影响。结果表明:在遮荫试验30%(林窗中心光)、10%(林窗边缘光)和3.5%(林下光)3个光处理及森林3种生境(林窗中心、林窗边缘和林下)条件下,种子萌发率差异无显著性差异,均达到95%以上,且平均萌发周期小于6 d。3个光处理下的幼苗生长、生物量分配模式及气体交换参数差异显著。30%光下绒毛番龙眼幼苗的根重比(RMR)和茎重比(SMR)最高,10%和3.5%光下幼苗的叶重比(LMR)最高,3.5%光下的叶面积比(LAR)显著高于30%光下。30%光下绒毛番龙眼幼苗的最大净光合速率(P_n_max)、暗呼吸速率(R_d)和光饱和点(I_sat)在3个光处理中均最大,光补偿点(I_comp)则无显著性差异。绒毛番龙眼幼苗具耐荫性,能够在低光环境下长期存活且能缓慢生长;同时具有适应林窗光环境生长的能力,如高的质量相对生长速率(RGR_M)和高度相对生长速率(RGR_H)。林窗的出现是绒毛番龙眼进行成功更新的必要条件,水分可能是限制其幼苗生境选择的另一环境因子。

关键词: 幼苗生长, 相对生长速率, 耐荫性, 西双版纳

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

于洋, 曹敏, 郑丽, 盛才余. 光对热带雨林冠层树种绒毛番龙眼种子萌发及其幼苗早期建立的影响. 植物生态学报, 2007, 31(6): 1028-1036. DOI: 10.17521/cjpe.2007.0130

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. Chinese Journal of Plant Ecology, 2007, 31(6): 1028-1036. DOI: 10.17521/cjpe.2007.0130

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2007.0130

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

图/表 7

表1 植物生长变量计算方法及单位

Table 1 Plant variables for growth and morphological analysis

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

表2 遮荫试验与西双版纳热带季节雨林试验绒毛番龙眼种子萌发率及平均萌发周期对比

Table 2 Final germination percentage and mean period of final germination of seeds of Pometia tomentosa under three light levels in shade houses and in a seasonal tropical rainforest of Xishuangbanna, Southwest China

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)

表3 遮荫试验绒毛番龙眼幼苗大小、生物量分配及存活率 (t=12 months) 参数比较

Table 3 Differences in seedling size parameters, biomass allocation and seedling survival (t=12 months) of Pometia tomentosa in shade house

	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)

图1 绒毛番龙眼幼苗叶面积在不同遮荫水平下(-●-30%光处理,-○-10%光处理,-▼-3.5%光处理)的叶面积动态对比图中数值为平均值±标准误差,Values are mean±SE

Fig.1 Comparison of seedling total leaf area dynamics of Pometia tomentosa under 30% (-●-), 10% (-○-), and 3.5% (-▼-) light treatments in shade house experiment

图2 遮荫试验不同光处理绒毛番龙眼幼苗的最大净光合速率、暗呼吸速率、光饱和点和光补偿点图中数值为5株幼苗(每株一片叶)测定的平均值±标准误差,相同字母表示不同环境间数值无显著性差异(ANOVA和Duncan's多重检验, p<0.05)

Fig.2 Maximum photosynthetic rate (Pnmax), dark respiration (Rd), light saturation point (Isat) and light compensation point (Icomp) of Pometia tomentosa seedlings grown in different light treatments shade houses Values are means (± SE) of five seedlings (one leaf per plant). Means followed by the same letter are not significantly different between environments (ANOVA and Duncan's multiple range test, p<0.05)

图3 西双版纳热带季节雨林中绒毛番龙眼种子散布(?)、林窗边缘(-●-)及林下幼苗库(-▽-)幼苗死亡率与月平均降水关系种子散布时间用箭头标出,幼苗死亡率为2003年9月至2006年10月3年的月平均值,月平均降水量为近40年来西双版纳降水量的月平均值

Fig. 3 Seedling mortality of seedling bank at edge of forest gap (-●-), understory forest (-▽-), and time of seed dispersal in relation to monthly rainfall (?) for Pometia tomentosa in a tropical seasonal rainforest in Xishuangbanna, Southwest China Time of seed dispersal is designated by arrows. Values of seedling mortality are means for three years monthly mortality from September 2003 to October 2006. Values of monthly rainfall are means for recent 40 years of Xishuangbanna

表4 不同植物生长参数与耐荫性之间的相关性分析

Table 4 Correlations between shade tolerance (RGRM in 3.5%), and various plant characteristics

	30% light	10% light	3.5% light
叶面积比LAR	-0.66^*	-0.71^*	-0.87^**
比叶重SLW	0.45	0.47	0.47
高度相对生长速率RGR_H	-0.44	-0.48	-0.53

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