Nitrogen additions modify the nursing effect of Scots pine on Sitka spruce via plant-soil feedback
Zhou, Yichen LU
; Tao, Tingting
; Cox, Filipa
and Johnson, David
(2026)
In Forest Ecosystems
16.
- Abstract
Nitrogen availability is thought to be a key factor that modifies the strength and direction of plant-soil feedback (PSF), but how nitrogen availability and PSF interact in forests remains unresolved. For example, PSF is one of the drivers underpinning the well-known nursing effect in the Atlantic forests of the UK and Ireland. In these systems, the nursing effect occurs when Scots pine ( Pinus sylvestris L.) facilitates the establishment of economically valuable Sitka spruce ( Picea sitchensis (Bong.) Carr). However, this effect has primarily been observed in nitrogen-limited environments. To isolate the PSF-driven component of the nursing effect, we used a two-phase PSF experiment and tested whether nitrogen additions diminish biomass... (More)
Nitrogen availability is thought to be a key factor that modifies the strength and direction of plant-soil feedback (PSF), but how nitrogen availability and PSF interact in forests remains unresolved. For example, PSF is one of the drivers underpinning the well-known nursing effect in the Atlantic forests of the UK and Ireland. In these systems, the nursing effect occurs when Scots pine ( Pinus sylvestris L.) facilitates the establishment of economically valuable Sitka spruce ( Picea sitchensis (Bong.) Carr). However, this effect has primarily been observed in nitrogen-limited environments. To isolate the PSF-driven component of the nursing effect, we used a two-phase PSF experiment and tested whether nitrogen additions diminish biomass differences among Sitka spruce grown in soils conditioned solely by Scots pine and Sitka spruce, and a soil that was a mix of both conditioning treatments. Our findings show that increasing nitrogen may promote Sitka spruce growth via microbial-mediated pathways (such as enhanced ectomycorrhizal (ECM) colonization and indirectly altered inorganic nitrogen availability), while inhibiting growth via inorganic nitrogen-mediated pathways (such as nutrient limitation). Thus, with increasing nitrogen additions, Sitka spruce biomass in conspecific soil increased to become similar to that in heterospecific soils, thereby weakening the PSF-driven nursing effect. Additionally, nitrogen additions shifted Sitka spruce in conspecific soil toward a faster root nutrient-acquisition strategy, potentially enhancing Sitka spruce nitrogen uptake and reducing biomass differences among soil types. Finally, Scots pine exerted a disproportionate influence in the mixed soil, as plant and soil responses more closely resembled those in Scots pine-conditioned soil than in Sitka spruce-conditioned soil. Our study highlights the interaction between soil microbial properties and nitrogen availability in shaping plant-soil feedback during early stages of tree establishment. These findings suggest matching forest planting to soil nitrogen availability, using nursing mixtures in low-nitrogen soils and Sitka spruce monocultures in high-nitrogen soils.
(Less)
- author
- Zhou, Yichen
LU
; Tao, Tingting
; Cox, Filipa
and Johnson, David
- organization
- publishing date
- 2026-08
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Ectomycorrhizal (ECM) colonization, Forest management, Nitrogen additions, Nursing mixture, Plant-soil feedback (PSF), Scots pine
- in
- Forest Ecosystems
- volume
- 16
- article number
- 100485
- publisher
- KeAi Communications Co.
- external identifiers
-
- scopus:105040983000
- ISSN
- 2095-6355
- DOI
- 10.1016/j.fecs.2026.100485
- language
- English
- LU publication?
- yes
- id
- 7d44c044-7aa5-49f2-8b0f-7aa4bf5b5b65
- date added to LUP
- 2026-08-31 13:38:54
- date last changed
- 2026-09-04 10:15:12
@article{7d44c044-7aa5-49f2-8b0f-7aa4bf5b5b65,
abstract = {{<p>Nitrogen availability is thought to be a key factor that modifies the strength and direction of plant-soil feedback (PSF), but how nitrogen availability and PSF interact in forests remains unresolved. For example, PSF is one of the drivers underpinning the well-known nursing effect in the Atlantic forests of the UK and Ireland. In these systems, the nursing effect occurs when Scots pine ( Pinus sylvestris L.) facilitates the establishment of economically valuable Sitka spruce ( Picea sitchensis (Bong.) Carr). However, this effect has primarily been observed in nitrogen-limited environments. To isolate the PSF-driven component of the nursing effect, we used a two-phase PSF experiment and tested whether nitrogen additions diminish biomass differences among Sitka spruce grown in soils conditioned solely by Scots pine and Sitka spruce, and a soil that was a mix of both conditioning treatments. Our findings show that increasing nitrogen may promote Sitka spruce growth via microbial-mediated pathways (such as enhanced ectomycorrhizal (ECM) colonization and indirectly altered inorganic nitrogen availability), while inhibiting growth via inorganic nitrogen-mediated pathways (such as nutrient limitation). Thus, with increasing nitrogen additions, Sitka spruce biomass in conspecific soil increased to become similar to that in heterospecific soils, thereby weakening the PSF-driven nursing effect. Additionally, nitrogen additions shifted Sitka spruce in conspecific soil toward a faster root nutrient-acquisition strategy, potentially enhancing Sitka spruce nitrogen uptake and reducing biomass differences among soil types. Finally, Scots pine exerted a disproportionate influence in the mixed soil, as plant and soil responses more closely resembled those in Scots pine-conditioned soil than in Sitka spruce-conditioned soil. Our study highlights the interaction between soil microbial properties and nitrogen availability in shaping plant-soil feedback during early stages of tree establishment. These findings suggest matching forest planting to soil nitrogen availability, using nursing mixtures in low-nitrogen soils and Sitka spruce monocultures in high-nitrogen soils.</p>}},
author = {{Zhou, Yichen and Tao, Tingting and Cox, Filipa and Johnson, David}},
issn = {{2095-6355}},
keywords = {{Ectomycorrhizal (ECM) colonization; Forest management; Nitrogen additions; Nursing mixture; Plant-soil feedback (PSF); Scots pine}},
language = {{eng}},
publisher = {{KeAi Communications Co.}},
series = {{Forest Ecosystems}},
title = {{Nitrogen additions modify the nursing effect of Scots pine on Sitka spruce via plant-soil feedback}},
url = {{http://dx.doi.org/10.1016/j.fecs.2026.100485}},
doi = {{10.1016/j.fecs.2026.100485}},
volume = {{16}},
year = {{2026}},
}