河北坝上乔灌木植物根系无机和有机氮吸收速率及其偏好

doi:10.17521/cjpe.2023.0287

摘要/Abstract

摘要： 土壤环境与植物自身属性影响着植物氮吸收, 明确河北坝上不同植物根系氮吸收偏好及其与土壤属性和根性状的关系, 可以增进对植物氮获取策略的理解, 同时为河北坝上混交防护林的构建提供理论依据。该研究选取张家口市康保县常见的农田防护林树种: 榆树(Ulmus pumila)、小叶杨(Populus simonii)、柠条锦鸡儿(Caragana korshinskii)和宁夏枸杞(Lycium barbarum)为研究对象, 采用¹⁵N同位素示踪技术测定植物根系对不同形态氮(硝态氮、铵态氮和甘氨酸氮)的吸收速率及其偏好, 并分析其与根系形态、构型和化学性状以及土壤环境的相关关系。结果显示: 宁夏枸杞根系偏好吸收硝态氮(硝态氮占总氮吸收的贡献率为46.05%), 其次是甘氨酸氮和铵态氮。小叶杨、榆树和柠条锦鸡儿根系各形态氮吸收的贡献率为铵态氮(44.91%-68.68%) >甘氨酸氮(22.63%-45.11%) >硝态氮(8.69%-9.98%)。Spearman相关性和冗余分析显示: 硝态氮的吸收速率与根直径和组织密度显著负相关, 与比根长和比表面积显著正相关, 即具有小的直径和组织密度、大的比根长和比表面积的根系表现出更高的硝态氮吸收速率。根分支强度与甘氨酸氮和总氮吸收速率显著正相关, 即具有高分支强度的根系其有机和无机氮吸收速率更高。根氮含量与铵态氮、甘氨酸氮和总氮吸收速率均显著负相关, 即低氮含量的根系表现出更高的氮吸收速率。4种防护林植物对3种形态氮的吸收存在显著差异, 其不仅与土壤氮含量有关, 还与植物根系自身的形态、构型和化学性状有关。基于植物氮吸收偏好以及根系结构性状与土壤肥力的影响综合考虑树种搭配, 在养分贫瘠的环境需减小植物的种间竞争, 最大限度地利用养分, 因此建议构建乔木-灌木(小叶杨-宁夏枸杞、榆树-宁夏枸杞)、灌木-灌木(宁夏枸杞-柠条锦鸡儿)混交防护林, 或是在原有小叶杨纯林或榆树纯林的林下补栽灌木宁夏枸杞。研究结果为河北坝上地区多树种防护林的构建提供理论依据。

关键词: 氮吸收速率, 氮吸收偏好, 根系性状, 同位素标记

Abstract:

Aims Understanding on how nitrogen uptake of plants is influenced by soil conditions and plant traits is crucial. Elucidating the nitrogen preferences of different plants and their interactions with soil properties and root traits, can enhance our understanding of plant nitrogen acquisition strategies. This knowledge can provide a theoretical basis for designing mixed-species plantation construction for arid and semi-arid region of northern China, like the Bashang region of Hebei Province.

Methods In Kangbao County, Zhangjiakou City, China, the tree species Ulmus pumila, Populus simonii, Caragana korshinskii, and Lycium barbarum were selected. The ¹⁵N isotope tracing technique was employed to quantify nitrogen uptake rates and preferences for different forms (nitrate, ammonium, and glycine) by these plants. Correlations among nitrogen uptake rates, root morphology, architecture, and chemistry, and soil characteristics were analyzed.

Important findings Lycium barbarum roots exhibited an uptake preference for nitrate with a contribution of 46.05%, followed by glycine and ammonium. For P. simonii, U. pumila, and C. korshinskii, the contributions of each form of nitrogen to total nitrogen uptake showed ammonium (44.91%-68.68%) > glycine (22.63%-45.11%) > nitrate (8.69%-9.98%). The nitrate uptake rate was significantly negatively correlated with root diameter and tissue density, but positively correlated with specific root length and specific surface area. This indicate that roots with smaller diameter, lower tissue density, larger specific root length, and greater specific surface area had higher nitrate uptake rate. Root branching intensity was positively correlated with the uptake rate of glycine and total nitrogen, suggesting that the roots with higher branching intensity take up organic and inorganic nitrogen more efficiently. Furthermore, there was a significant negative correlation between root nitrogen content and ammonium as well as glycine or total nitrogen uptake rate; implying that roots with lower nitrogen content displayed higher nitrogen uptake rate. The observed differences in the nitrogen uptake patterns among four species were influenced not only by soil nitrogen content but also by various morphological, architectural, and chemical traits of the roots. Based on the plant nitrogen uptake preference and relationships with root structural traits and soil fertility, it is necessary to minimize the interspecific competition of plants and maximize the use of nutrients in nutrient poor environment. Therefore, we recommended to construct a mixed-species shelterbelt such as tree-shrub combination (P. simonii - L. barbarum, U. pumila - L. barbarum) or shrub-shrub combination (C. korshinskii - L. barbarum), or to replant shrubs under the pure P. simonii or U. pumila plantations. These research results provide valuable insights for the constructing mixed-species shelterbelts in Bashang region of Hebei Province.

Key words: nitrogen uptake rate, nitrogen uptake preference, root trait, isotope labeling

刘倩愿, 俞振东, 张微微. 河北坝上乔灌木植物根系无机和有机氮吸收速率及其偏好. 植物生态学报, 2024, 48(10): 1361-1373. DOI: 10.17521/cjpe.2023.0287

LIU Qian-Yuan, YU Zhen-Dong, ZHANG Wei-Wei. Uptake rate and preference of inorganic and organic nitrogen in roots of tree and shrub plants in Bashang, Hebei, China. Chinese Journal of Plant Ecology, 2024, 48(10): 1361-1373. DOI: 10.17521/cjpe.2023.0287

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图/表 8

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防护林 Shelterbelt	经纬度 Latitude and longitude	海拔 Altitude (m)	年龄 Age (a)	株高 Tree height (m)	基径 Basal diameter (cm)	防护林长度 Length of shelterbelt (m)	防护林宽度 Width of shelterbelt (m)	树间距 Spacing of trees (m)
小叶杨 Populus simonii	114.74° E, 42.02° N	1 445	29	8.10 ± 0.41	25.29 ± 2.16	1 000	10	2.5
榆树 Ulmus pumila	114.79° E, 42.12° N	1 312	36	6.94 ± 0.53	21.16 ± 1.96	1 800	25	2.5
宁夏枸杞 Lycium barbarum	114.74° E, 41.93° N	1 448	15	2.24 ± 0.16	4.17 ± 0.93	500	5	0.1
柠条锦鸡儿 Caragana korshinskii	114.80° E, 42.13° N	1 283	17	0.89 ± 0.13	1.30 ± 0.15	5 000	10	0.1

防护林 Shelterbelt	经纬度 Latitude and longitude	海拔 Altitude (m)	年龄 Age (a)	株高 Tree height (m)	基径 Basal diameter (cm)	防护林长度 Length of shelterbelt (m)	防护林宽度 Width of shelterbelt (m)	树间距 Spacing of trees (m)
小叶杨 Populus simonii	114.74° E, 42.02° N	1 445	29	8.10 ± 0.41	25.29 ± 2.16	1 000	10	2.5
榆树 Ulmus pumila	114.79° E, 42.12° N	1 312	36	6.94 ± 0.53	21.16 ± 1.96	1 800	25	2.5
宁夏枸杞 Lycium barbarum	114.74° E, 41.93° N	1 448	15	2.24 ± 0.16	4.17 ± 0.93	500	5	0.1
柠条锦鸡儿 Caragana korshinskii	114.80° E, 42.13° N	1 283	17	0.89 ± 0.13	1.30 ± 0.15	5 000	10	0.1

物种 Species	pH	含水量 Water content (%)	有机碳含量 Organic carbon content (g·kg^-1)	全氮含量 Total nitrogen content (g·kg^-1)	铵态氮含量 Ammonium nitrogen content (mg·kg^-1)	硝态氮含量 Nitrate nitrogen content (mg·kg^-1)	甘氨酸氮含量 Glycine nitrogen content (mg·kg^-1)
小叶杨 Populus simonii	8.31 ± 0.04^ab	14.18 ± 0.93^b	15.18 ± 0.79^ab	1.81 ± 0.24^ab	6.80 ± 0.52^a	20.84 ± 1.84^b	0.04 ± 0.01^a
榆树 Ulmus pumila	8.41 ± 0.09^a	16.72 ± 2.03^ab	14.46 ± 0.87^bc	1.50 ± 0.13^b	6.66 ± 0.65^a	34.21 ± 3.18^a	0.04 ± 0.01^a
宁夏枸杞 Lycium barbarum	8.07 ± 0.11^b	21.02 ± 0.93^a	18.06 ± 1.27^a	2.23 ± 0.18^a	6.56 ± 0.28^a	39.99 ± 3.13^a	0.03 ± 0.00^ab
柠条锦鸡儿 Caragana korshinskii	8.49 ± 0.01^a	16.98 ± 0.62^ab	11.55 ± 0.50^c	1.61 ± 0.12^b	6.41 ± 0.24^a	11.59 ± 1.31^c	0.02 ± 0.00^b

物种 Species	pH	含水量 Water content (%)	有机碳含量 Organic carbon content (g·kg^-1)	全氮含量 Total nitrogen content (g·kg^-1)	铵态氮含量 Ammonium nitrogen content (mg·kg^-1)	硝态氮含量 Nitrate nitrogen content (mg·kg^-1)	甘氨酸氮含量 Glycine nitrogen content (mg·kg^-1)
小叶杨 Populus simonii	8.31 ± 0.04^ab	14.18 ± 0.93^b	15.18 ± 0.79^ab	1.81 ± 0.24^ab	6.80 ± 0.52^a	20.84 ± 1.84^b	0.04 ± 0.01^a
榆树 Ulmus pumila	8.41 ± 0.09^a	16.72 ± 2.03^ab	14.46 ± 0.87^bc	1.50 ± 0.13^b	6.66 ± 0.65^a	34.21 ± 3.18^a	0.04 ± 0.01^a
宁夏枸杞 Lycium barbarum	8.07 ± 0.11^b	21.02 ± 0.93^a	18.06 ± 1.27^a	2.23 ± 0.18^a	6.56 ± 0.28^a	39.99 ± 3.13^a	0.03 ± 0.00^ab
柠条锦鸡儿 Caragana korshinskii	8.49 ± 0.01^a	16.98 ± 0.62^ab	11.55 ± 0.50^c	1.61 ± 0.12^b	6.41 ± 0.24^a	11.59 ± 1.31^c	0.02 ± 0.00^b

指标 Factor		缩写 Abbreviation	氮吸收速率 Nitrogen uptake rate (µg·g^-1·h^-1)
指标 Factor		缩写 Abbreviation	铵态氮 Ammonium nitrogen	硝态氮 Nitrate nitrogen	甘氨酸氮 Glycine nitrogen	总氮 Total nitrogen
根性状 Root trait	根直径 Root diameter (mm)	AD	-0.021	-0.688^**	-0.108	0.003
	根组织密度 Root tissue density (g·cm^-2)	RTD	0.264	-0.637^**	0.099	0.290
	比根长 Specific root length (m·g^-1)	SRL	-0.287	0.694^**	-0.094	-0.309
	比表面积 Specific surface area (cm²·g^-1)	SSA	-0.324	0.714^**	-0.100	-0.335
	分支比 Branching ratio	BR	-0.358	-0.218	-0.176	-0.235
	分支强度 Branching intensity (cm^-1)	BI	0.403	0.175	0.638^**	0.512^*
	根碳含量 Root carbon content (%)	RC	-0.592^*	0.053	-0.594^*	-0.662^**
	根氮含量 Root nitrogen content (%)	RN	-0.816^**	0.061	-0.685^**	-0.758^*
	根碳氮比 Ratio of carbon to nitrogen	C:N	0.823^*	-0.109	0.700^**	0.765^**
土壤 Soil	土壤pH Soil pH	pH	0.137	-0.492	0.225	0.308
	土壤含水量 Soil water content (%)	SWC	-0.686^**	0.346	-0.500^*	-0.571^*
	土壤有机碳含量 Soil organic carbon content (g·kg^-1)	SC	-0.072	0.613^*	-0.079	-0.115
	土壤全氮含量 Soil total nitrogen content (g·kg^-1)	SN	-0.442	0.584^*	-0.443	-0.462
	土壤铵态氮含量 Soil ammonium nitogen content (mg·kg^-1)	SAM	-0.035	0.448	0.015	0.082
	土壤硝态氮含量 Soil nitrate nitogen content (mg·kg^-1)	SNT	-0.275	0.750^**	0.088	-0.156
	土壤甘氨酸氮含量 Soil glycine nitogen content (mg·kg^-1)	SGLY	0.564^*	0.290	0.490	0.507^*