The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability

Nitrogen (N) fertilization is an effective practice for restoring degraded grasslands, which might strongly depend on the rooting system and resource competition of individual plant species. The purpose of this study is to explore a method to distinguish the response of various plant root architectu...

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Main Authors: Yiming Zhao, Hui Li, Fei Peng, Dabu Xilatu, Qing Chen, Shan Lin
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Agronomy
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Online Access:https://www.mdpi.com/2073-4395/15/1/12
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author Yiming Zhao
Hui Li
Fei Peng
Dabu Xilatu
Qing Chen
Shan Lin
author_facet Yiming Zhao
Hui Li
Fei Peng
Dabu Xilatu
Qing Chen
Shan Lin
author_sort Yiming Zhao
collection DOAJ
description Nitrogen (N) fertilization is an effective practice for restoring degraded grasslands, which might strongly depend on the rooting system and resource competition of individual plant species. The purpose of this study is to explore a method to distinguish the response of various plant root architectures to the resource availability in a mixed ecosystem in situ. Field experiments were conducted using isotope techniques in conjunction with a specialized experimental design at a semiarid grassland location featuring heavily grazed (HG) and moderately grazed (MG) grassland sites with different dominant species. The same amounts of water and <sup>15</sup>N-labelled fertilizer were uniformly supplied by a tube fertigation system at soil depths of 0, 15 and 45 cm. At both the HG and MG sites, there was a significant increase in aboveground net primary production (ANPP), water use efficiency (WUE) and <sup>15</sup>N use efficiency (<sup>15</sup>NUE) at the community level with increasing depths of fertigation. The ANPP and plant N uptake exhibited higher values at the HG site compared to those at the MG site, while <sup>15</sup>NUE and <sup>15</sup>N abundance were significantly lower at the HG site. The annual species <i>Salsola collina</i> Pall. exhibited the highest aboveground biomass (AGB) and <sup>15</sup>N abundance compared to all other species. Furthermore, the <sup>15</sup>N enrichment of <i>S</i>. <i>collina</i> increased with greater depths of <sup>15</sup>N-labelled fertilization, indicating that <i>S</i>. <i>collina</i> might develop a more extensive root system in response to water and N addition in the degraded grassland. Our study highlights that using isotope methods could indirectly distinguish root distribution and resource acquisition. In the recovery of degraded grassland by N fertilizer, we should not only consider the aboveground biomass but also pay special attention to the resource competition of individual plant species due to the possible discrepancy in rooting systems.
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spelling doaj-art-6d08e0e24c294118a28cf2bacf07ae712025-01-24T13:16:20ZengMDPI AGAgronomy2073-43952024-12-011511210.3390/agronomy15010012The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource AvailabilityYiming Zhao0Hui Li1Fei Peng2Dabu Xilatu3Qing Chen4Shan Lin5Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, ChinaCollege of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, ChinaCollege of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, ChinaCollege of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, ChinaTianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin 300387, ChinaCollege of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, ChinaNitrogen (N) fertilization is an effective practice for restoring degraded grasslands, which might strongly depend on the rooting system and resource competition of individual plant species. The purpose of this study is to explore a method to distinguish the response of various plant root architectures to the resource availability in a mixed ecosystem in situ. Field experiments were conducted using isotope techniques in conjunction with a specialized experimental design at a semiarid grassland location featuring heavily grazed (HG) and moderately grazed (MG) grassland sites with different dominant species. The same amounts of water and <sup>15</sup>N-labelled fertilizer were uniformly supplied by a tube fertigation system at soil depths of 0, 15 and 45 cm. At both the HG and MG sites, there was a significant increase in aboveground net primary production (ANPP), water use efficiency (WUE) and <sup>15</sup>N use efficiency (<sup>15</sup>NUE) at the community level with increasing depths of fertigation. The ANPP and plant N uptake exhibited higher values at the HG site compared to those at the MG site, while <sup>15</sup>NUE and <sup>15</sup>N abundance were significantly lower at the HG site. The annual species <i>Salsola collina</i> Pall. exhibited the highest aboveground biomass (AGB) and <sup>15</sup>N abundance compared to all other species. Furthermore, the <sup>15</sup>N enrichment of <i>S</i>. <i>collina</i> increased with greater depths of <sup>15</sup>N-labelled fertilization, indicating that <i>S</i>. <i>collina</i> might develop a more extensive root system in response to water and N addition in the degraded grassland. Our study highlights that using isotope methods could indirectly distinguish root distribution and resource acquisition. In the recovery of degraded grassland by N fertilizer, we should not only consider the aboveground biomass but also pay special attention to the resource competition of individual plant species due to the possible discrepancy in rooting systems.https://www.mdpi.com/2073-4395/15/1/12grazing historyfertigation<sup>15</sup>N isotoperesource acquisitionspecies competitionaboveground net primary production
spellingShingle Yiming Zhao
Hui Li
Fei Peng
Dabu Xilatu
Qing Chen
Shan Lin
The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
Agronomy
grazing history
fertigation
<sup>15</sup>N isotope
resource acquisition
species competition
aboveground net primary production
title The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
title_full The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
title_fullStr The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
title_full_unstemmed The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
title_short The Restoration Effect of Degraded Grassland Depends on the Response of Species Root Distribution to Resource Availability
title_sort restoration effect of degraded grassland depends on the response of species root distribution to resource availability
topic grazing history
fertigation
<sup>15</sup>N isotope
resource acquisition
species competition
aboveground net primary production
url https://www.mdpi.com/2073-4395/15/1/12
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