Do young trees contribute to soil labile carbon and nitrogen recovery?

Bai, Shahla Hosseini; Blumfield, Timothy John; Reverchon, Frédérique; Amini, Sevda

doi:10.1007/s11368-014-1028-8

Cited by 12 publications

(1 citation statement)

References 44 publications

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“…Therefore, one‐way ANOVAs were performed for each plantation using the treatment (sampling position)—soil depth combination as the fixed effect. This approach allowed us to compare within and between combinations of sampling positions and soil depths (Bai et al, 2015; Nguyen et al, 2017). Duncan's multiple range tests were used when significant differences were detected among fixed‐effect means.…”

Section: Methodsmentioning

confidence: 99%

Root architecture, root biomass and nutrient cycling in a mixed‐species agroforestry system

Bai,

Muqaddas,

Trueman

et al. 2023

Land Degrad Dev

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Understanding root development in soil profiles of agroforestry systems is challenging. It is uncertain to what extent the proximity of cash crops, such as cocoa and coffee, to shade trees reduces nutrient concentrations in the topsoil and whether the cash crops continue to develop fine roots in the topsoil when they are planted in close proximity to shade trees. We aimed to investigate micro‐ and macro‐nutrient concentrations in the soil profile and understand root architecture using a novel DNA metabarcoding approach in an agroforestry system where cocoa and coffee were interplanted with a shade tree, canarium. Soil and root samples were collected from (1) cocoa‐only, (2) cocoa‐canarium, (3) canarium‐only positions in a cocoa plantation, (4) coffee‐only, (5) coffee‐canarium and (6) canarium‐only positions in a coffee plantation. Proximity of shade trees did not limit nutrient concentrations for cash crops. Topsoil concentrations of total N (TN: 0.59% and 0.69%), phosphorus (P: 7.28 and 6.65 mg/kg), potassium (K: 360 and 755 mg/kg) and calcium (Ca: 1865 and 1044 mg/kg) under cocoa and coffee trees, respectively, did not differ significantly from those under the corresponding canarium trees. Soil TN, K and Ca concentrations were well above minimum required concentrations under both cocoa and coffee. DNA metabarcoding showed that canarium trees occupied deeper rooting zones (30–80 cm soil depth) than cocoa and coffee trees (0–30 cm soil depth). DNA metabarcoding demonstrated greater root colonisation of the topsoil by cocoa and coffee than canarium, suggesting that canarium had the potential to extract nutrients from deeper soil layers. Soil Ca concentrations were associated with cocoa root biomass whereas soil NO3−‐N concentrations were associated with coffee root biomass. Our study highlighted the value of selecting suitable shade trees that maintain soil nutrient concentrations for cash crops. Furthermore, DNA metabarcoding can facilitate root distribution studies in complex agroforestry systems, thus providing insights into appropriate tree‐planting designs.

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Section: Methodsmentioning

confidence: 99%

Root architecture, root biomass and nutrient cycling in a mixed‐species agroforestry system

Bai,

Muqaddas,

Trueman

et al. 2023

Land Degrad Dev

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Labile C dynamics reflect soil organic carbon sequestration capacity: Understory plants drive topsoil C process in subtropical forests

et al. 2019

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The huge background pool of soil organic carbon (SOC) is likely to impede the ready detection of SOC changes. We propose to explore SOC changes by monitoring the dynamics of soil labile organic carbon (LOC); namely if LOC could be largely retained in soils rather than respired rapidly, the SOC would be ready to be sequestered. The effects of the two major functional groups of plants, that is, canopy trees and understory plants, on SOC accumulation were then illustrated with this LOC-based approach. The characteristics of LOC and SOC of topsoils (0-20 cm) in a field manipulation experiment with 5-yr treatments of understory removal and tree girdling in both a young and a mature Eucalyptus plantations were examined. The concentration and potential turnover time of soil LOC were used to indicate the state of vegetation-induced C accumulation in soils, which were estimated by a sequential fumigation-incubation procedure. Soil natural abundances of 13 C and 15 N were measured to reflect the proportion of newly retained LOC in soils. We found that, in the young plantation, understory removal did not significantly affect both soil LOC and SOC concentrations, but significantly increased the potential turnover time of soil LOC. In contrast, in the mature plantation, understory removal significantly decreased soil LOC and SOC concentrations, but did not significantly alter the potential turnover time of soil LOC. However, tree girdling did not significantly affect SOC concentration, soil LOC concentration, or potential turnover time in either the young plantation or the mature plantation. These results demonstrated that understory plantderived C was one of the major components of LOC pool in topsoils, and it may be readily mineralized in the young plantation but accumulated as an important fraction of SOC in the mature plantation. This study suggests that the LOC-based approach is potentially useful in monitoring SOC changes and improves our understanding of how plant functional groups and soil fertility status could jointly affect LOC and SOC dynamics. In considering the great contribution of understory plants to SOC processes, we propose that understory plants should be maintained in subtropical plantation ecosystems.

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