Seed traits and recruitment limitation of northern marginal Cercidiphyllum japonicum populations in China

doi:10.17520/biods.2020095

Abstract

Abstract:

Cercidiphyllum japonicum is a Tertiary relict tree, and recruitment limitation leads to the population declining dramatically. However, the causes of recruitment limitation are currently unclear. This study tests whether early life history traits (seed germination) may limit seedling recruitment of northern C. japonicum populations in China. In this study, we collected C. japonicum seeds in the Qinling-Taihang Mountains and measured their seed morphological traits, seed nutrient content, seed mass, seed vitality, and seed germination. ANOVA and correlation analysis results showed that: (1) There were significant differences in seed length, germination percentage, mean germination time (MGT), and seed nitrogen and phosphorus contents among C. japonicum populations. (2) In the Tianshui population, the percentage of germinating seeds was the highest (21.77%), and MGT was the longest (11.12 d), while the opposite results were found in Luanchuan population (germination percentage = 1.38%, and MGT = 3.47 d). (3) The percentage of germination of the Jiyuan population was higher at 25℃ than at other temperatures (10℃, 15℃ and 20℃), whereas the germination percentages of Tianshui, Ningshan, Luanchuan and Qinshui populations had no significant differences at these different temperatures. Additionally, there were no significant differences in days of the first germination record (T₀) in Luanchuan population at four temperature levels, while T₀ decreased with increasing germination temperature in the other provenances. (4) Germination percentage was significantly correlated with seed vitality, which was positively related with seed mass, and seed nitrogen and phosphorus contents. Seed intrinsic attributes (seed mass, seed nitrogen and phosphorus contents) influenced seed vitality which directly influenced germination percentage. Different provences had difference germination responses to temperature, notably in T₀ and MGT. In this study, we found evidence of seed germination limiting seedling recruitment of northern Chinese C. japonicum populations. The main causes were as follow: (1) Seed may germinate in October after maturation in September, but the seedlings have short growing period and could not survive under low temperature during winter. (2) Seeds have low germination percentage. (3) Seed vitality decrease abruptly in coming spring.

Key words: Cercidiphyllum japonicum, recruitment limitation, seed mass, seed vitality, germination percentage, northern marginal distribution, Qinling-Taihang Mountains

Jing Li, Tianyang Zhou, Xueli Lu, Xintao Li, Bin Sun, Hongjie Meng. Seed traits and recruitment limitation of northern marginal Cercidiphyllum japonicum populations in China[J]. Biodiv Sci, 2020, 28(10): 1161-1173.

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URL: https://www.biodiversity-science.net/EN/10.17520/biods.2020095

https://www.biodiversity-science.net/EN/Y2020/V28/I10/1161

Figures/Tables 9

References 62

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环境因子 Environmental factors	秦岭 Qinling Mountains			太行山脉 Taihang Mountains
环境因子 Environmental factors	天水 Tianshui	宁陕 Ningshan	栾川 Luanchuan	沁水 Qinshui	济源 Jiyuan
纬度 Latitude	34.29° N	33.58° N	33.69° N	35.4° N	35.25° N
经度 Longitude	106.58° E	108.48° E	111.78° E	112.04° E	112.12° E
海拔 Altitude (m)	1,592	1,741	1,478	1,392	589
年均温 Annual mean temperature (℃)	8.8	8.2	8.5	7.1	11.6
年降水量 Annual mean precipitation (mm)	719	919	893	694	612
土壤碳含量 Soil C content (%)	8.87	15.88	8.78	9.31	11.32
土壤氮含量 Soil N content (%)	0.57	1.14	0.86	0.75	0.75
土壤磷含量 Soil P content (mg/g)	0.11	0.09	0.11	0.09	0.13
9月平均温 Mean monthly temperature in September (℃)	14	14	15	13	18
10月平均温 Mean monthly temperature in October (℃)	9	9	9	8	13
11月平均温 Mean monthly temperature in November (℃)	3.2	3	3.3	1.4	5.3
12月平均温 Mean monthly temperature in December (℃)	-1.9	-1.7	-2.2	-5	-0.9

环境因子 Environmental factors	秦岭 Qinling Mountains			太行山脉 Taihang Mountains
环境因子 Environmental factors	天水 Tianshui	宁陕 Ningshan	栾川 Luanchuan	沁水 Qinshui	济源 Jiyuan
纬度 Latitude	34.29° N	33.58° N	33.69° N	35.4° N	35.25° N
经度 Longitude	106.58° E	108.48° E	111.78° E	112.04° E	112.12° E
海拔 Altitude (m)	1,592	1,741	1,478	1,392	589
年均温 Annual mean temperature (℃)	8.8	8.2	8.5	7.1	11.6
年降水量 Annual mean precipitation (mm)	719	919	893	694	612
土壤碳含量 Soil C content (%)	8.87	15.88	8.78	9.31	11.32
土壤氮含量 Soil N content (%)	0.57	1.14	0.86	0.75	0.75
土壤磷含量 Soil P content (mg/g)	0.11	0.09	0.11	0.09	0.13
9月平均温 Mean monthly temperature in September (℃)	14	14	15	13	18
10月平均温 Mean monthly temperature in October (℃)	9	9	9	8	13
11月平均温 Mean monthly temperature in November (℃)	3.2	3	3.3	1.4	5.3
12月平均温 Mean monthly temperature in December (℃)	-1.9	-1.7	-2.2	-5	-0.9

种子性状 Seed traits	平均值 Mean	最大值 Max.	最小值 Min.	变异系数 Coefficient of variation (%)	df	F	P
种子质量 Seed mass (mg)	0.56	0.67	0.52	11.04	4	0.46	0.678
种子长度 Seed length (cm)	0.52	0.58	0.41	12.66	4	6.53	< 0.001
种子宽度 Seed width (cm)	0.26	0.28	0.23	7.45	4	40.36	0.074
种子萌发率 Germination percentage (%)	14.40	21.77	1.38	57.97	4	22.07	< 0.001
初始萌发时间 Days of the first germination record (d)	4.48	5.59	2.33	27.93	4	8.14	0.206
平均萌发时间 Mean germination time (d)	7.46	11.12	3.47	37.31	4	31.32	< 0.001
种子碳含量 Seed C content (%)	44.50	45.51	43.82	1.62	4	2.33	0.081
种子氮含量 Seed N content (%)	1.22	1.41	0.85	18.66	4	3.36	< 0.05
种子磷含量 Seed P content (mg/g)	2.13	3.23	1.09	37.84	4	7.97	< 0.001

种子性状 Seed traits	平均值 Mean	最大值 Max.	最小值 Min.	变异系数 Coefficient of variation (%)	df	F	P
种子质量 Seed mass (mg)	0.56	0.67	0.52	11.04	4	0.46	0.678
种子长度 Seed length (cm)	0.52	0.58	0.41	12.66	4	6.53	< 0.001
种子宽度 Seed width (cm)	0.26	0.28	0.23	7.45	4	40.36	0.074
种子萌发率 Germination percentage (%)	14.40	21.77	1.38	57.97	4	22.07	< 0.001
初始萌发时间 Days of the first germination record (d)	4.48	5.59	2.33	27.93	4	8.14	0.206
平均萌发时间 Mean germination time (d)	7.46	11.12	3.47	37.31	4	31.32	< 0.001
种子碳含量 Seed C content (%)	44.50	45.51	43.82	1.62	4	2.33	0.081
种子氮含量 Seed N content (%)	1.22	1.41	0.85	18.66	4	3.36	< 0.05
种子磷含量 Seed P content (mg/g)	2.13	3.23	1.09	37.84	4	7.97	< 0.001

种子性状 Seed traits	天水 Tianshui (TS)	宁陕 Ningshan (NS)	栾川 Luanchuan (LC)	沁水 Qinshui (QS)	济源 Jiyuan (JY)
种子质量 Seed mass (mg)	0.67 ± 0.05^a	0.57 ± 0.04^a	0.53 ± 0.12^a	0.52 ± 0.09^a	0.53 ± 0.05^a
种子长度 Seed length (cm)	0.55 ± 0.02^a	0.57 ± 0.03^a	0.52 ± 0.07^a	0.56 ± 0.02^a	0.41 ± 0.02^b
种子宽度 Seed width (cm)	0.27 ± 0.01^a	0.28 ± 0.01^a	0.26 ± 0.04^ab	0.27 ± 0.01^a	0.23 ± 0.01^b
萌发率 Germination percentage (%)	21.77 ± 1.62^a	18.03 ± 2.07^a	1.38 ± 0.37^c	19.86 ± 1.80^a	10.95 ± 0.91^b
初始萌发时间 Days of the first germination record (d)	5.59 ± 0.55	4.75 ± 0.26	2.33 ± 0.55	4.73 ± 0.28	5.01 ± 0.31
平均萌发时间 Mean germination time (d)	11.12 ± 0.63^a	6.54 ± 0.72^a	3.47 ± 0.64^b	8.25 ± 0.32^a	7.94 ± 0.32^a
贮存4个月种子活力 Vitality of seeds stored for 4 months (%)	54.83 ± 3.85^a	49.25 ± 5.23^ab	37.33 ± 7.07^b	47.09 ± 2.22^ab	52.22 ± 2.85^a
贮存7个月种子活力 Vitality of seeds stored for 7 months (%)	26.83 ± 8.28^a	15.67 ± 6.92^ab	1.11 ± 0.59^b	11.82 ± 3.38^ab	21.11 ± 4.07^ab
种子碳含量 Seed C content (%)	44.22 ± 0.59^ab	43.96 ± 0.48^b	43.82 ± 0.18^b	44.97 ± 0.36^ab	45.51 ± 0.34^b
种子氮含量 Seed N content (%)	1.39 ± 0.1^a	1.26 ± 0.09^a	0.85 ± 0.08^b	1.17 ± 0.08^a	1.41 ± 0.09^a
种子磷含量 Seed P content (mg/g)	2.51 ± 0.37^ab	2.11 ± 0.28^bc	1.09 ± 0.18^d	1.72 ± 0.18^cd	3.23 ± 0.19^a