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Plant–soil feedback (PSF) is conventionally characterized by plant biomass growth, yet it remains unclear how PSF affects plant nutrient acquisition strategies (e.g. nutrient absorption and nutrient resorption) associated with plant growth, particularly under changing soil environments. A greenhouse experiment was performed with seedlings of Pinus elliottii Englem and conditioned soils of monoculture plantations (P. elliottii and Cunninghamia lanceolata Hook). Soil sterilization was designed to test plant phosphorus (P) acquisition strategy with and without native soil fungal communities. Soils from P. elliottii and C. lanceolata plantations were used to explore the specific soil legacy effects on two different P acquisition pathways (absorption and resorption). Phosphorus addition was also applied to examine the separate and combined effects of soil abiotic factors and soil fungal factors on P acquisition pathways. Due to diminished mycorrhizal symbiosis, PSF prompted plants to increasingly rely on P resorption under soil sterilization. In contrast, P absorption was employed preferentially in the heterospecific soil, where species-specific pathogenic fungi could not affect P absorption. Higher soil P availability diluted the effects of soil fungal factors on the trade-off between the two P acquisition pathways in terms of the absolute PSF. Moreover, P addition plays a limited role in terms of the relative PSF and does not affect the direction and strength of relative PSF. Our results reveal the role of PSF in regulating plant P acquisition pathways and highlight the interaction between mycorrhizal and pathogenic fungi as the underlying mechanism of PSF. [ABSTRACT FROM AUTHOR]

Home‐field advantage (HFA) states that litter decomposes faster in "home" than in "away" soil, due to the specialization of decomposer organisms in decomposing litter derived from their local plant community. Demonstration of the HFA effect has been overwhelmingly based on aboveground leaf litter despite the fact that roots play a pivotal role in carbon (C) and nutrient cycling.Labile C input in root exudates and newly shed root litters can enhance the activity of soil microorganisms, which in turn can favour the breakdown of older root litter, also referred to as the priming effect. It remains, however, unclear how the addition of fresh root‐derived inputs affects HFA on the decomposition of absorptive roots (ARs) and transport roots (TRs), which have a different chemical composition.Here, we conducted a two‐stage (endogenous C consumption versus exogenous C priming) reciprocal transplant microcosm experiment to explore the effects of HFA on the decomposition of lower‐quality ARs and higher‐quality TRs of two subtropical tree species (Pinus elliottii and Cunninghamia lanceolata) and their responses to either labile (glucose) or recalcitrant (fresh ARs) C additions.Decomposition of lower‐quality ARs exhibited neutral HFA, while decomposition of higher‐quality TRs exhibited positive HFA. The absence of HFA for short‐lived ARs was possibly due to the legacy effect of their chemical defences on decomposition. The neutral HFA for ARs became negative with glucose addition, which was linked to the dissimilarity of fungal community between the home and away soils. Neither glucose nor fresh ARs additions changed the HFA pattern of TRs, implying that these long‐lived roots play a reinforced role in soil C accumulation when they decompose away from their origins.These results indicate that the effect of HFA on decomposition differs between ARs and TRs, and could be modified by the priming effect induced by the root‐derived C input. In general, our findings highlight that complex "HFA‐priming" interactions on root decomposition should be explicitly considered in the paradigm of belowground C dynamics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Summary: Timing (phenology) and amount (production) are two integral facets of root growth, and their shifts have profound influences on below‐ground resource acquisition. However, the environmental control and the effects of nitrogen (N) deposition on the production and phenology of ectomycorrhizal (ECM) roots remain unclear.Using a 4 yr minirhizotron experiment, we explored the control of the production and three phenophases (initiation, peak, and cessation of growth) of ECM roots in two soil layers and investigated their dynamic responses to N addition in a seasonally dry subtropical Pinus elliottii forest.We found a stronger control of water availability on the production and a stronger control of temperature on the phenology of ECM roots under ambient conditions. Temperature was correlated positively with initiation and negatively with cessation, especially in the shallow layer. N addition did not affect the phenology of ECM roots but increased their production by modifying N and phosphorus (P) stoichiometry in the soil and foliage.Our findings suggest a greater sensitivity of production than phenology of ECM roots to N addition. The increased production of ECM roots under N addition could be driven by N‐induced P limitation or some combination of below‐ground resources (P, N, water). [ABSTRACT FROM AUTHOR]

Summary: Fine roots of woody plants comprise multiple root orders, which can be functionally partitioned into two pools: absorptive fine roots (AFRs, orders 1, 2) and transport fine roots (TFRs, orders 3–5). However, the function‐based fine‐root dynamics and especially their responses to increased nitrogen (N) availability remain unclear. We explored dynamic responses of both AFRs and TFRs of Pinus elliottii to N addition in subtropical China based on a 4‐yr minirhizotron experiment and a two‐stage – early (0.5 yr) vs late (4 yr) – decomposition experiment. N addition increased the production, mortality, and turnover of AFRs but not TFRs. High rates of N persistently inhibited AFR decomposition but affected TFR decomposition differentially at the early (no effect) and late (negative effect) stages. The increased production of AFRs was driven by N‐induced decrease in foliar and soil phosphorus (P) concentrations. The decreased decomposition of AFRs might be due to the increased acid‐unhydrolyzable residues in decomposing roots. AFRs are the resource‐acquiring module, the increased carbon allocation to AFRs may represent a P‐acquiring strategy when N no longer limits growth of P. elliottii. Our results suggest that AFRs and TFRs respond differently to N deposition, both in terms of production, mortality, and turnover and in terms of decomposition. [ABSTRACT FROM AUTHOR]

• C:N:P ratios differed significantly among species. • Forest type significantly influenced C:N:P ratios of leaves and rhizosphere soils. • Foliar and root C:N:P ratios were constrained by rhizosphere. Ecological stoichiometry provides important information for understanding biogeochemical cycling in forest ecosystems. The stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) in the leaves, roots and rhizosphere soils of co-existing overstory trees and understory shrubs and herbs within a forest ecosystem, however, remain poorly understood. The C, N and P concentrations and their stoichiometric ratios of the leaves, roots and rhizosphere soils were studied for three overstory trees, three understory shrubs and two herbs in three plantations of Cunninghamia lanceolata , Pinus massoniana and Pinus elliottii in subtropical China. Mostly, the foliar and root C:N ratios were significantly higher for overstory trees than understory shrubs and herbs. Forest type significantly influenced the C:N and C:P ratios of the leaves and rhizosphere soils across all species. The C:N ratio in the leaves and roots were positively and negatively correlated with that in rhizosphere soil, respectively. The N:P in leaves and roots were negatively and positively correlated with that of rhizosphere soil, respectively. We found that foliar and root C:N:P stoichiometry varied greatly among plant species and forest types, which was mainly constrained by the rhizosphere soil. The opposite relationship of C:N:P stoichiometry in the leaves and roots with rhizosphere soil offers new insights into the interaction between above- and belowground process of forest ecosystems. [ABSTRACT FROM AUTHOR]

Increase of anthropogenic atmospheric nitrogen (N) deposition markedly influences biogeochemical cycles of elements in a wide range of ecosystems. However, our knowledge of how N deposition affects stoichiometry of plants in forests experiencing regular seasonal droughts remains limited. Using a 3-year (2013–2015) N-manipulative experiment, we examined the stoichiometric responses of ten mineral elements, including the most limiting elements (N and P) to plant growth, base cations (K, Ca, and Mg), and trace metal cations (Mn, Zn, Cu, Al, and Fe) in resource-acquiring organs (foliage vs. absorptive roots) of Pinus elliottii to N additions in both wet and dry seasons in a seasonally dry subtropical forest. Stoichiometric responses of both organs depended on rate of N addition (generally stronger under high rate) and season. N additions increased foliar [N] and decreased foliar [P] only in dry season and the relative changes in foliar N:P ratio were twice higher in dry than wet seasons, suggesting an aggravated P limitation in dry season. The stoichiometry of absorptive roots was more responsive to N additions than that of foliage, especially for the base cations. N additions increased [Mn] and decreased Fe:Mn ratio in both organs, indicating increased risk of Mn 2 + toxicity to this tree species. Our results have implications for understanding the N-induced changes in nutrient limitation of forests influenced by seasonal drought, and highlight the contrasting stoichiometric responses of above- and below-ground resource-acquiring plant organs to N loading. [ABSTRACT FROM AUTHOR]