Gradient variations in rhizospheric soil exchangeable cations across a forest-steppe transect
Han, Jiaxin (Hebei University)
Wang, Ruzhen (Hebei University)
Sardans i Galobart, Jordi (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Liu, Heyong (Hebei University)
He, Peng (Tianjin Normal University)
Deng, Huanhuan (Hebei University)
Ma, Weiyi (Hebei University)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Han, Xingguo (Hebei University)
Jiang, Yong (Hebei University)

Data:	2024
Resum:	The forest-steppe ecotone (FSE) is vulnerable to climate change and valuable to predict ecosystem succession. Although species diversity covaries with climatic factors and changes gradually across FSE transects, aligning with "Whittaker's hierarchy theory", whether soil nutrients follow a similar distribution pattern remains unclear. We studied the ecological gradient changes in effective cation-exchange capacity (ECEC, sum of exchangeable Ca2+, Mg2+, K+ and Na+) in the near-neutral-pH rhizosphere and bulk soils along the north-south zonal transect of the Hulunbuir FSE, China. The 230-km transect includes hierarchical transitions from two closed forests through two FSE to four meadow steppes. For both rhizosphere and bulk soils, soil ECEC were the highest in meadow steppes followed by closed forests and FSE area. ECEC were inversely correlated with soil water content but positively with soil pH. Therefore, the distribution of ECEC along the forest-steppe transect did not conform to a hierarchical distribution and decoupled from vegetation transitions, possibly due to the fact that the distribution of soil pH, plant uptake and leaching break the uniformity of ECEC variation along the gradient. In closed forests and FSE ecosystems, the ECEC and exchangeable Ca2+ in rhizosphere soils were higher than those in bulk soil, indicating that rhizosphere processes may alleviate cation limitation in these ecosystems. The study substantially improves our understanding of soil nutrient mobilization and soil fertility across forest-steppe ecotones which helps projecting ecosystem succession. It further highlights the critical role of rhizosphere processes in modulating hierarchical vegetation transition along environmental gradients and provides avenues for future research opportunities.
Ajuts:	Agencia Estatal de Investigación PID2020-115770RB-I Agencia Estatal de Investigación TED2021-132627B-I00 Agencia Estatal de Investigación PID2022-140808NB-I00
Nota:	Altres ajuts: The Fundación Ramón Areces grant CIVP20A6621
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Cation-exchange capacity ; Rhizosphere ; Ecotone ; Forest-steppe transect ; Environmental gradient ; Ecosystem type
Publicat a:	Catena, Vol. 245 (October 2024) , art. 108330, ISSN 1872-6887

DOI: 10.1016/j.catena.2024.108330

Disponible a partir de: 2026-10-31 Postprint

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