1 Introduction
Accurate accounting of ecosystem carbon requires not only estimating the size of carbon pools, but also their temporal dynamics [
1,
2]. This distinction is especially important in belowground, where carbon may occur in dead organic components such as litter, wood and soil organic matter, as well as living components such as roots, rhizomes and storage organs. Each of these has different turnover rates, management sensitivities and implications for long-term sequestration. In this context, tree stumps and bamboo rhizomes provide a useful contrast between two fundamentally different belowground carbon pools. Tree stumps are remnants of harvested or dead trees and are generally incorporated into dead organic matter (DOM) accounting, where their carbon dynamics are governed mainly by structural persistence, decomposition and gradual transfer to soil organic carbon [
3-
5]. In contrast, bamboo rhizomes are living belowground organs that store and redistribute carbon, support rapid shoot emergence, maintain clonal integration and sustain stand renewal [
6-
8]. This contrast underscores the need for carbon-accounting frameworks to distinguish between these distinct belowground pools, based on the striking differences in their biological status and ecological function.
This biological contrast between dead stumps and living bamboo rhizomes has direct implications for carbon accounting. Stump pools align relatively well with existing stock- and decay-based approaches because they can be classified as DOM and represented using biomass, wood density, decay class, decomposition rate and soil-transfer pathways [
3-
5,
9]. Although uncertainties remain in decay rates, decay-class transitions, soil carbon transfer and spatial heterogeneity of decomposition, the main accounting challenge for stumps is parameterization rather than pool definition. However, bamboo rhizomes present a different problem in such a standardized modeling framework. Their role in carbon dynamics lies not only in the amount of biomass stored belowground, but also in living functions that regulate future carbon uptake, including non-structural carbohydrate storage and mobilization, resource transfer between mature culms and emerging shoots, clonal integration, and continuous carbon investment in maintenance and renewal [
6-
8,
10]. When these functions are collapsed into generic BGB categories, accounting frameworks may capture part of the stock but miss the processes that determine regeneration, persistence and long-term carbon balance in bamboo systems.
The core challenge in bamboo carbon accounting is therefore not simply insufficient measurement, but inadequate definition and classification. Conventional BGB estimates often rely on tree-root assumptions and may not capture the clonal, rhizome-dominated architecture of bamboo systems [
11,
12]. This limitation is important because bamboo rhizomes are not merely structural BGB. Field studies show that bamboo can allocate substantial belowground carbon, that annual rhizome production and turnover contribute measurably to stand-level carbon dynamics, and that rhizome-mediated integration supports regeneration and productivity after shoot emergence [
8,
13,
14]. Bamboo ecosystems may also contribute to longer-term carbon storage through soil organic carbon and phytolith-occluded carbon (PhytOC) pathways, further linking rhizome dynamics to both short-term productivity and persistent carbon pools [
15,
16]. These lines of evidence suggest that bamboo rhizomes should be treated as dynamic living carbon pools rather than as generic root biomass, DOM or an indistinct component of soil carbon.
Distinguishing dead tree stump carbon from bamboo rhizome carbon is also critical for evaluating management effects and climate-mitigation potential. Stump carbon mainly represents delayed emissions from deadwood and partial transfer to soil organic matter, whereas rhizome carbon is embedded in a living network that can sustain future biomass accumulation through storage, redistribution and regeneration. This means that disturbance affects the two pools through different mechanisms. For tree stumps, management primarily alters decomposition rates, soil transfer and the timing of carbon emission. For bamboo rhizomes, disturbance, harvesting intensity, understory removal, rhizome severance and accelerated decay can alter carbon balance not only by reducing BGB, but also by disrupting carbohydrate redistribution, clonal integration and regenerative capacity [
10,
14,
17]. These process-based effects are rarely captured in current accounting approaches, even though they directly influence whether bamboo systems maintain long-term carbon sequestration or shift toward weakened and less stable carbon pools.
Here, we synthesize evidence on the dynamics of dead tree stumps and bamboo rhizomes to clarify the striking differences between these two belowground carbon pools in terms of biological status, carbon-cycling mode, ecological function and accounting applicability. We use tree stumps as a reference case for a relatively well-defined DOM pool, and bamboo rhizomes as a contrasting example of a living, clonal and process-dependent belowground carbon network. Specifically, we compare their carbon-pool properties, examine how rhizome degradation may alter bamboo carbon sequestration, identify gaps in current accounting frameworks, and propose a rhizome-focused approach for bamboo systems. By distinguishing dead residue-based carbon storage from living rhizome-mediated carbon regulation, this synthesis aims to improve the representation of bamboo belowground dynamics and support more accurate assessments of bamboo’s contribution to carbon neutrality strategies and nature-based climate mitigation.
2 Contrasting Properties of Carbon Pools in Tree Stumps and Bamboo Rhizomes
2.1 Biological status and carbon-cycling mode
Tree stumps and bamboo rhizomes represent contrasting, but not absolutely mutually exclusive, belowground carbon pools. Most harvested or dead tree stumps are treated as dead organic residues, whereas bamboo rhizomes are living belowground organs embedded in clonal growth networks. Some tree species can retain living stump tissues and resprout, but their post-harvest regeneration is not equivalent to the continuous, connected rhizome network characteristic of bamboo [
18]. Tree stumps function mainly as structurally persistent DOM. Their carbon dynamics are governed by wood density, decomposer activity, environmental conditions and the gradual transfer of decomposed material into soil organic carbon pools [
3-
5,
9,
19]. Empirical studies show that stump and root systems can contain substantial carbon stocks, including > 12 Mg C ha
−1 (1 ha = 10,000 m
2) in roots of
Populus deltoides plantations [
20]. Evidence from semi-natural forests further indicates that dead wood and coarse woody debris can turn over slowly and maintain carbon storage over decadal timescales [
21]. However, deadwood persistence depends on both substrate quality and decomposer activity, with wood density and other material traits strongly influencing decomposition rates across systems [
22].
Bamboo rhizomes, in contrast, are living biomass pools that combine storage, transport and metabolic functions. In Moso bamboo (
Phyllostachys edulis), rhizome networks redistribute carbohydrates to support rapid shoot emergence and contribute to cyclical variation in biomass allocation between on-years and off-years [
23]. In China, Moso bamboo forests dominate national bamboo resources, accounting for approximately 70% of the national bamboo forest area. Li et al. estimated approximately 600 Tg C for the total ecosystem carbon stock of China’s Moso bamboo forests, including aboveground biomass, BGB and soil organic carbon, rather than rhizomes alone [
24]. Using the field-based estimate of approximately 21 Mg C ha
−1 for Moso bamboo BGB [
13] and a national area of 4.68 million ha, the corresponding belowground pool is approximately 98 Tg C [
25]. Bamboo carbon storage is therefore not confined to aboveground culms but also depends strongly on belowground components. For instance, some sympodial bamboo species allocate up to 71% of their carbon belowground [
26], and bamboo groves such as
Dendrocalamus giganteus and
Bambusa vulgaris can store more than 150 Mg C ha
−1, rivaling many tree-based systems and agroforestry systems [
27-
29]. Meanwhile, studies in Colombia and Ghana reaffirm its potential, with bamboo systems contributing nearly half of total ecosystem carbon stocks and exhibiting sequestration capacities comparable to or exceeding those of native trees; reported total ecosystem carbon stocks in these studies range from 198 to 330 Mg C ha
−1, including vegetation and soil pools [
30,
31]. The climate mitigation potential of bamboo forests may be further amplified when harvested bamboo products and longer-lived product pathways are included [
13,
24,
32].
2.2 Ecological function and management sensitivity
The contrasting biological status of tree stumps and bamboo rhizomes leads to different ecological functions in carbon cycling. Tree stumps mainly influence carbon dynamics after aboveground growth has ceased. Their ecological role is to retain carbon temporarily in deadwood, slow its emission through decomposition, and contribute part of the decomposed material to soil organic carbon pools [
5,
9]. Their contribution to carbon sequestration therefore depends largely on decay rate, residence time, decomposer activity and the proportion of stump-derived carbon that is stabilized in soil.
Bamboo rhizomes play a more active role because they remain physiologically connected to aboveground culms and newly emerging shoots. Rather than functioning only as stored biomass, rhizomes regulate carbon allocation through non-structural carbohydrate storage, mobilization and transfer across the clonal network. These processes support rapid shoot emergence, culm recruitment and stand renewal, and thereby influence future aboveground productivity and carbon accumulation [
6-
8]. In this sense, rhizome carbon is not only a belowground stock, but also part of a living regulatory system that sustains bamboo growth and regeneration.
These functional differences create contrasting sensitivities to disturbance and management. For tree stumps, management mainly affects carbon outcomes by changing stump retention, decomposition conditions and soil-transfer pathways. For bamboo rhizomes, management can affect carbon sequestration not only by changing BGB, but also by altering the integrity of the living network. Rhizome severance, understory removal, intensive harvesting and other disturbances may weaken belowground connectivity, reduce carbohydrate redistribution, disrupt clonal integration and limit regenerative support for new shoots [
10,
14,
17]. Thus, stump carbon is primarily sensitive to decomposition processes, whereas rhizome carbon is sensitive to both biomass loss and functional degradation of the clonal network.
This distinction is important for carbon accounting because changes in rhizome function may affect future carbon uptake before they are fully reflected in measured biomass stocks. Accounting frameworks that record only the size of the belowground pool may therefore capture the retained carbon in stumps more readily than the process-based contribution of rhizomes to regeneration, productivity and long-term carbon balance in bamboo systems.
2.3 Implications for carbon-pool classification
These differences, as synthesized in Fig. 1, indicate that the contrast between tree stumps and bamboo rhizomes is not merely a matter of parameter adjustment, but one of carbon-pool classification. It highlights differences in biological status, carbon-cycling mode, and ecological function between tree stumps and bamboo rhizomes. Existing accounting approaches can misrepresent belowground carbon pools when living rhizome systems are treated as generic root biomass or when distinct dead-organic-matter components are not clearly differentiated within broader deadwood categories [
1,
12,
13]. This matters because tree stumps and bamboo rhizomes differ not only in biological status, but also in the ecological processes through which they influence carbon storage and emission.
The current Intergovernmental Panel on Climate Change (IPCC) framework illustrates both the usefulness and the limitation of this classification. The 2019 Refinement to the 2006 IPCC Guidelines places living BGB within the living biomass pool and dead wood within DOM, so most dead tree stumps can be represented within the latter category, whereas living bamboo rhizomes are nominally included in BGB [
33]. However, the guidelines do not provide a separate category for rhizome-dominated clonal networks or explicitly represent their storage, transport, clonal integration and regenerative functions.
Bamboo rhizomes should also be distinguished from conventional BGB categories. Transport roots primarily acquire and move water and nutrients, whereas rhizomes combine storage, transport, clonal integration and regenerative functions. Coarse belowground biomass is a size-based category and does not by itself identify whether the tissue is a living rhizome network, a root system or residual necromass. Dead organic matter and decomposing post-harvest residues represent non-living material and delayed decomposition pathways, whereas intact bamboo rhizomes remain physiologically connected to culms and emerging shoots [
6,
8,
13,
17].
Tree stumps fit relatively well within existing DOM frameworks because they are structurally persistent, decomposition-driven, and amenable to stock-based measurement and decay-related flux estimation [
3-
5]. Bamboo rhizomes, however, do not conform to this logic. Their significance lies not only in stored biomass, but also in redistribution, regeneration, and stand-level carbon allocation [
6-
8]. A more appropriate interpretation is therefore to treat bamboo rhizomes as dynamic living belowground carbon pools rather than as generic root fractions or post-harvest belowground residues.
3 Bamboo Rhizomes as Functional Belowground Carbon Networks
3.1 NSC storage, transfer and shoot emergence
Rhizome degradation refers broadly to the loss of functional integrity in rhizome networks, including physical disruption caused by management or harvesting activities as well as declines in belowground connectivity and carbon-regulatory function under disturbance or decay [
10,
16,
34]. The role of bamboo rhizomes in the regeneration of bamboo stands lies in their function as central nodes for the storage and redistribution of non-structural carbohydrates (NSCs), which provide the primary metabolic support for new shoot emergence and early culm growth [
6,
7,
35]. Moso bamboo achieves its well-known “explosive growth” within approximately 35–40 days after shoot emergence, and this rapid development depends heavily on NSCs transferred from attached mature culms through the rhizome system [
6]. During this period, stored carbohydrates in culms, branches, and rhizomes of mature bamboos were heavily mobilized, with culms contributing the largest share, until newly sprouted shoots establish their own photosynthetic capacity about four months later [
6]. Recent physiological and biochemical analyses further show that the rhizome-culm system operates in an age-dependent manner: adult culms display the strongest capacity to mobilize and supply NSCs, whereas younger and older culms prioritize their own growth or starch storage, respectively, and adult rhizomes favor sugar transport over starch accumulation [
7]. Experimental manipulation of mother culm number likewise revealed that retaining more mother plants significantly enhanced the growth rate and diameter of new shoots in younger clumps, reflecting a direct dependence of shoot performance on maternal carbohydrate supply, with diminishing effects in older clumps [
36]. Complementary studies of NSCs and water dynamics further demonstrated that, prior to leafing, newly sprouted culms rely heavily on both previously stored and freshly synthesized carbohydrates transferred from mother culms, coordinated with reciprocal water transport through rhizomes [
37]. Researchers also suggest that NSCs regulate not only energy mobilization and sugar transport, but also hormonal signaling and gene expression pathways associated with cell division, metabolism, and wall synthesis during rapid shoot elongation [
35]. Comparative analyses of monopodial and sympodial bamboos further indicate that phenological differences strongly affect NSC storage and allocation patterns, suggesting that management strategies should be tailored to species-specific growth dynamics [
38].
Overall, these processes indicate that bamboo rhizomes function as an integrated support system for shoot establishment, culm recruitment, and aboveground biomass growth (Fig. 2). Although young culms gradually become independent carbon assimilators, their initial dependence on rhizome-mediated reserves shows that the integrity and vigor of the rhizome network are critical for sustained productivity and carbon accumulation in bamboo ecosystems.
3.2 Clonal integration and whole-stand resource connectivity
The functioning of bamboo forests as clonal systems has been strongly linked to their ability to redistribute carbon, nutrients, and water through rhizome-mediated integration, thereby sustaining both productivity and resilience [
14,
17,
39]. Isotopic tracing experiments
in situ confirmed that nitrogen translocation between mature and young ramets of
Phyllostachys edulis is bidirectional yet follows a demand-driven pattern in which more nitrogen moves from mature to young ramets, ensuring rapid growth during critical stages such as winter shoot emergence [
17]. Controlled pot experiments further showed that physiological integration significantly enhanced nitrogen use efficiency, especially in heterogeneous nutrient environments, with connected ramets displaying higher nitrogen use efficiency (NUE) than severed ones and thereby improving whole-stand nutrient efficiency [
14]. Furthermore, long-term manipulations of nitrogen and phosphorus inputs in Moso bamboo forests similarly demonstrated that belowground carbon allocation and soil respiration responded differently to nutrient treatments, with integration buffering against potential nutrient imbalances that might otherwise destabilize net ecosystem productivity [
39]. Beyond nitrogen cycling, clonal integration also plays a regulatory role in water and carbon transport, as studies of interconnected culms have shown that severing rhizomes reduces new shoot growth and reduces assimilation capacity, highlighting the systemic dependence of bamboo stands on belowground connectivity [
14,
37].
Similar patterns of resource distribution have also been observed in other bamboo taxa. Dwarf bamboo (
Sasa palmata) exhibited comparable integration, with
15N movement from nutrient-rich to nutrient-poor ramets or from shaded to light-exposed ones, reflecting a “division of labour” in which functional sinks govern nitrogen flow [
40]. At the microbial level, nitrogen fertilization practices were shown to alter rhizosphere microbial communities by regulating clonal nitrogen integration pathways: parent and rhizome fertilization favored nitrogen retention and stable microbial functions, whereas offspring fertilization enhanced bacterial diversity but increased the risk of nitrogen loss [
41]. Neotropical bamboo (
Merostachys neesii) has likewise been associated with substantial bamboo-linked nitrogen inputs, highlighting the broader ecological significance of bamboo-mediated nutrient dynamics beyond East Asian systems [
42]. While the specific mechanisms reported across bamboo taxa may differ, the broader principle of resource redistribution through rhizome-mediated connectivity remains a shared feature of clonal bamboo systems [
40,
42].
These findings indicate that clonal integration in bamboo forests is not merely a passive structural linkage, but an active physiological and ecological process that coordinates resource redistribution across the network, enhances nutrient use efficiency, buffers environmental changes, and maintains high productivity. Disruption of this connectivity can interrupt new shoot establishment, carbon and nitrogen assimilation, and microbial stability, thereby reducing the long-term carbon sequestration potential of bamboo ecosystems [
14,
17,
41].
3.3 Rhizome maintenance, renewal and regenerative costs
The persistence and productivity of bamboo ecosystems are tightly bound to the continuous investment of carbon into their rhizome networks, which function both as storage organs and as conduits for resource redistribution [
7,
8]. Long-term observation indicates that maintaining rhizome systems requires a measurable and sustained carbon investment. For instance, in
Phyllostachys edulis, annual carbon input into rhizomes reaches approximately 0.90 Mg C ha
−1, accounting for nearly 9.5% of newly produced biomass, while rhizome turnover remains slower than in other organs [
8]. Rather than simply indicating the size of the belowground pool, these values point to the continuing allocation costs required to maintain rhizome persistence, renewal, and stand-level regenerative capacity.
Belowground investment in bamboo forests is also highly dynamic and management sensitive. Experimental understory removal significantly reduced fine root biomass and production, altered total belowground carbon allocation, and showed that carbon investment belowground can shift markedly under disturbance regimes [
10]. Studies across dwarf bamboo species likewise indicate that environmental stress often shifts biomass allocation toward rhizomes and older culms at the expense of new shoot growth, revealing a trade-off in which maintenance of the underground system takes precedence over aboveground expansion [
43-
45]. At broader scales, regional climatic gradients and soil nutrient availability further influence biomass partitioning and thereby affect the resources available for rhizome renewal [
46]. Historical nutrient balance studies similarly suggest that bamboo plantations require continuous nutrient and carbon input to sustain both above- and belowground compartments, with litterfall-related nutrient losses amplifying the metabolic burden on rhizomes [
47]. In addition, clonal integration studies show that clonal fragment size and ramet connectivity shape rhizosphere carbon and nitrogen processes. Larger clonal fragments can enhance the survival of shaded ramets through greater resource storage, but they also increase the maintenance burden borne by the system as a whole [
48].
Taken together, these findings indicate that bamboo rhizomes impose a persistent regenerative cost within the ecosystem carbon budget (Fig. 2). They require continuous investment for maintenance, repair, and expansion, and under stress or accelerated decay this investment can divert resources away from culm recruitment and aboveground productivity. The capacity of bamboo stands to sustain rapid biomass turnover and carbon sequestration therefore depends on how carbon is balanced between rhizome upkeep and new culm production under varying environmental and management conditions.
4 How Rhizome Degradation Alters Carbon Sequestration in Bamboo Systems
4.1 Network disruption and reduced regenerative capacity
The contribution of bamboo rhizomes to carbon sequestration depends not only on their biomass stock, but also on the integrity of the living network through which resources are stored, transferred, and redistributed [
6,
7]. This network-level vulnerability provides the basis for understanding how rhizome degradation affects carbon balance and regenerative capacity. Rhizome degradation, including accelerated decay and loss of network integrity, can substantially alter the carbon balance of bamboo ecosystems, shifting them from efficient carbon sinks toward weaker or even unstable carbon pools under poor management or when system integrity is compromised [
16,
34]. These cascading effects of rhizome degradation on carbon dynamics are conceptually illustrated in Fig. 3. Because bamboo forests function as clonal systems sustained by rhizome-mediated integration, disruption of belowground continuity affects more than carbon stock alone. It impedes the translocation of non-structural carbohydrates [
6,
7] and weakens clonal integration [
14,
17], thereby reducing the metabolic and physiological support available for new shoot establishment and subsequent aboveground biomass accumulation. Once rhizome continuity is weakened, new shoot establishment, carbon and nitrogen assimilation, and microbial stability may all decline [
14,
17,
37,
41], ultimately reducing the long-term carbon sequestration potential of bamboo ecosystems.
4.2 Accelerated decomposition and destabilization of long-term carbon pools
At the biochemical level, bamboo ecosystems have been identified as global hotspots for phytolith-occluded carbon, a highly stable and long-lived carbon form, with meta-analyses indicating that bamboo forests contain the highest phytolith and PhytOC contents among terrestrial ecosystems [
16]. This long-term sequestration function is especially important because a substantial fraction of bamboo PhytOC is stored belowground: field studies in China show that nearly 23%–39% of total PhytOC in bamboo occurs in belowground organs, particularly rhizomes, implying that rhizome decay can directly undermine long-term carbon stability [
15]. Additional studies further show that PhytOC sequestration varies across bamboo taxa and environmental settings, with production fluxes in Chinese bamboo forests alone exceeding 4.5 × 10
8 kg CO
2 annually and local sequestration being influenced by factors such as phylogeny, lithology, and topographic position [
49-
51]. Evidence from sympodial bamboo species likewise suggests that phytolith-bound sequestration can make a measurable contribution through foliage and litter pathways [
52].
At the ecosystem level, both unmanaged decay and intensive disturbance can destabilize this long-term sequestration function. When bamboo culms, rhizomes, and litter are left unmanaged, decomposition and soil respiration are enhanced, while drought and seasonal extremes can further suppress carbon uptake and accelerate respiration fluxes, thereby reducing net ecosystem productivity [
53]. By contrast, intensive management may increase aboveground biomass carbon storage but simultaneously reduce soil carbon stocks through enhanced soil respiration, highlighting the fragility of soil carbon pools under disturbance [
34]. Targeted interventions can nevertheless buffer some of these losses. Silicon fertilization can enhance phytolith deposition and increase PhytOC accumulation in Moso bamboo [
54], while minimizing soil disturbance, applying organic fertilizers, and regulating harvest cycles help preserve both soil organic carbon and rhizome integrity [
55]. Restoration studies of native bamboo systems, such as
Arundinaria gigantea in North America, further illustrate that dense rhizome networks contribute to soil stabilization and long-term carbon storage, and that rhizome mortality may weaken both carbon retention and ecological resilience [
56].
Altogether, accelerated rhizome decay can trigger immediate carbon emission, erode long-lived PhytOC reserves, and destabilize soil carbon pools. Conversely, management strategies that preserve rhizome integrity and reduce unnecessary disturbance may help buffer these losses and sustain the long-term sequestration function of bamboo ecosystems.
5 Applicability and Limitations of Current Carbon-Accounting Frameworks
5.1 Stump pools fit relatively well within DOM accounting
Current forest carbon-accounting frameworks have largely been developed for tree-based systems, with the result that tree stump pools are embedded in a more mature accounting framework than bamboo rhizome systems. National and international guidelines, including those issued by the IPCC (2019), require DOM pools, including stumps, to be systematically included in inventories using protocols based on volume estimates, decay-class assignments, and wood density values [
33]. Empirical studies show that stumps are a substantial but often undervalued component of the deadwood pool. For example, detailed inventories in Switzerland found that stumps alone account for nearly 25% of total deadwood, highlighting the risk of substantial underestimation when they are excluded [
4]. At the national scale in Sweden, stump-root systems were estimated to contain nearly 495 Mt CO
2 equivalents [
3], equivalent to about 135 Mt C and 12% of the carbon stored in living trees in Sweden’s production forests [
57]. Although the two estimates are not perfectly matched in year and pool definition, this comparison still highlights the substantial contribution of tree stump systems to the full forest carbon pool.
In addition to contributing to carbon pools, fluxes from tree stump decomposition can also account for a substantial proportion of total carbon flux. Long-term chronosequence studies in coniferous forests have shown that CO
2 emissions from stumps peak within the first decade after harvest and decline sharply after two decades, indicating that stumps can act as short-lived but intense emission hotspots following logging [
9]. Complementary decomposition studies in boreal and temperate ecosystems further suggest that up to 47% of carbon from tree stumps may be transferred into soil organic carbon pools, highlighting stumps as both sources of atmospheric CO
2 and contributors to soil organic carbon formation [
5]. In black pine systems, stump decomposition has also been shown to redistribute 32% of carbon into litter fractions, with cascading effects on soil microbial activity [
58]. These findings are consistent with global syntheses showing that decomposition from the dead tree stumps is a non-negligible component of carbon cycling, regulated by climatic factors, wood quality, and biotic agents such as insects and fungi [
19,
59]. In tropical regions, termite-driven decomposition can accelerate carbon loss by up to 63% in canopy gaps, further emphasizing the existence of spatial hotspots of stump and deadwood carbon flux [
60].
Thus, these findings indicate that tree stump carbon pools fit relatively well within DOM accounting because they are structurally persistent and amenable to stock- and decay-based quantification, even though substantial uncertainties remain in decay-class transitions, decomposition trajectories, and the spatial heterogeneity of fluxes [
4,
5,
9].
5.2 Bamboo rhizomes are systematically underestimated
The role of bamboo rhizomes and root systems in carbon accounting remains underexplored within current international guidelines, where they are often aggregated into broad BGB categories without being explicitly distinguished as living, rhizome-dominated carbon pools [
8,
13]. The problem is not that bamboo rhizomes fall outside existing BGB categories, but that their contribution is frequently represented through generic allometric assumptions developed for tree-root systems, which fail to capture the clonal, rhizome-dominated architecture of bamboo [
11,
12]. This mismatch becomes significant when quantitative evidence is considered. Field-based assessments of
Phyllostachys edulis show that BGB, primarily composed of rhizomes, accounts for nearly 21 Mg C ha
−1 [
13]. Detailed studies further demonstrate that annual carbon sink into rhizomes can reach approximately 0.90 Mg C ha
−1 and represent 9.5% of total new biomass, while turnover remains slower than in other organs, indicating that rhizomes function as both storage structures and long-term regulatory nodes for stand-level carbon allocation [
8]. Furthermore, studies in subtropical Moso bamboo plantations likewise show that rhizomes can increase soil respiration under nitrogen addition, indicating that rhizome-related carbon fluxes might be sensitive to local environmental and management conditions [
61]. At the same time, generic methods for BGB commonly assume that only 20%–26% of total vegetation biomass resides belowground [
29], whereas studies of Moso bamboo show that empirical root-to-shoot ratios can reach as much as 96%, far exceeding such generalized estimates and underscoring the inadequacy of tree-based accounting factors for rhizome-dominated systems [
11,
12]. Current approaches therefore do not necessarily omit bamboo rhizomes from accounting categories, but they tend to underestimate their contribution when tree-based assumptions are applied to rhizome-dominated bamboo systems. In response to these limitations, advances such as ground-penetrating radar offer an important opportunity to improve the accuracy and scalability of rhizome biomass estimation and belowground carbon accounting in bamboo ecosystems [
62].
5.3 Major accounting gaps revealed by a comparative perspective
A comparative reading of tree stump and bamboo rhizome studies reveals that the core problem is not simply data scarcity, but a mismatch between carbon pool identity and accounting logic. This mismatch can be summarized across three dimensions, namely pool classification, process representation, and system boundary, as shown in Table 1.
The process gap is equally consequential. Existing stump accounting can at least capture decomposition-related stocks and fluxes, whereas bamboo rhizome accounting still rarely represents NSC redistribution, clonal integration, or regenerative support, even though these functions directly affect subsequent culm recruitment and stand-level sequestration. This omission is not trivial, as rhizome respiration alone may offset nearly 18% of annual net ecosystem productivity in Moso bamboo ecosystems [
6,
7,
63].
The boundary gap further extends the issue beyond the stand itself. Bamboo carbon benefits depend not only on in-stand biomass, but also on post-harvest residence time, product pathways, and the fate of residual rhizomes left
in situ. When these broader trajectories are ignored, the climate value of bamboo systems may be either underestimated or overstated [
24,
28,
64]. Existing life cycle assessment (LCA) studies have already evaluated a range of bamboo products, showing that post-harvest processing, product longevity, and end-of-life stages can strongly influence overall climate outcomes [
65,
66]. However, these LCA approaches remain insufficiently connected to the living belowground dynamics emphasized in this review, including rhizome-mediated regeneration, residual rhizome persistence, and delayed belowground carbon release [
6-
8]. Integrating rhizome-focused ecosystem accounting with LCA would therefore provide a more complete framework for linking in-stand carbon processes to harvested biomass pathways and life cycle climate effects [
65,
66]. Together, these gaps indicate that the challenge in bamboo carbon accounting is not merely one of measurement precision, but of adapting accounting logic to a living, clonal, and process-dependent belowground system.
6 Toward a Rhizome-Focused Framework for Bamboo Carbon Accounting
6.1 Reclassifying bamboo rhizomes as dynamic living belowground carbon pools
The evidence reviewed above indicates that the main challenge in bamboo carbon accounting is not simply to improve biomass estimation, but to reconsider how bamboo rhizomes are precisely classified within carbon-pool frameworks. Unlike tree stumps, which can generally be accommodated within dead organic matter accounting, bamboo rhizomes remain part of a living belowground system whose ecological significance lies in storage, redistribution, regeneration, and stand persistence [
8,
12,
13,
36]. To date, available evidence further shows that bamboo rhizomes function not merely as root biomass, but as active metabolic and transport nodes that regulate non-structural carbohydrate redistribution, support rapid shoot emergence, and maintain clonal persistence [
6,
7,
17]. A more appropriate starting point is therefore to classify bamboo rhizomes as dynamic living belowground carbon pools rather than as generic root fractions or dead stump residues.
6.2 Incorporating process-based belowground functions into accounting
Reclassification alone, however, is insufficient if accounting frameworks continue to focus only on static belowground stocks. The ecological importance of bamboo rhizomes lies not only in stored biomass, but also in the living processes through which they influence future carbon uptake and stand persistence. Empirical studies show that rhizomes mediate NSC storage and transfer during explosive shoot growth, sustain clonal integration across interconnected ramets, and require continuous carbon investment for maintenance, repair, and renewal [
6-
8,
14,
36]. These functions directly affect culm recruitment, aboveground biomass production, and long-term sequestration performance. Bamboo carbon accounting should therefore move beyond static stock estimation to include process-based belowground functions such as carbohydrate redistribution, network connectivity, regenerative support, maintenance costs, and, where possible, rhizome respiration and turnover. Otherwise, an important part of bamboo’s carbon-regulatory role will remain invisible even when BGB is measured more accurately.
6.3 Extending accounting boundaries from in-stand pools to post-harvest pathways
A rhizome-focused framework also requires extending carbon accounting beyond stand-level biomass pools. Available evidence suggests that the climate value of bamboo depends not only on in-stand biomass, but also on post-harvest carbon residence, product longevity, utilization pathways, and the fate of residual belowground structures. Previous studies have suggested that bamboo can contribute to durable product storage and carbon farming, whereas others caution that its sequestration value may be overstated if culm lifespans remain short and harvested biomass is not transferred into longer-lived carbon pools [
24,
28,
64,
67]. This means that evaluating bamboo systems solely based on standing biomass may underestimate or misrepresent their broader carbon consequences. Therefore, a more complete framework should extend from in-stand living pools, including rhizomes, to post-harvest pathways such as durable bamboo products, recycling, and end-of-life emissions. It should also account for the fate of residual rhizomes left
in situ after harvest. These belowground structures may either continue to function as living carbon-regulating networks or, under disturbance and decay, shift towards delayed carbon release and residual necromass pathways [
8,
16,
34]. In this regard, bamboo carbon accounting requires not only better measurement of living belowground dynamics, but also broader system boundaries that link ecosystem processes with harvested biomass outcomes. Existing life cycle assessment studies of bamboo products provide an important step in this direction, but they remain only weakly connected to rhizome-mediated belowground processes, residual rhizome persistence, and delayed carbon release. Integrating rhizome-focused ecosystem accounting with life cycle assessment would therefore help connect in-stand carbon dynamics with harvested biomass pathways and whole-life climate effects.
6.4 Implications for carbon neutrality and nature-based climate solutions
Integrating both deadwood carbon pools of tree stumps and dynamic BGB pools of bamboo rhizomes has direct implications for carbon neutrality because these reservoirs shape long-term carbon budgeting and the reliability of mitigation evaluation and application. In China, forest ecosystems sequestered more than 2.5 Pg of biomass carbon and 1.27 Pg of soil carbon from 2006 to 2020, offsetting nearly 12% of national emissions [
68]. Provincial evidence from regions such as Shaanxi and Yunnan further suggests that forest carbon growth trajectories can align with regional carbon peak and neutrality roadmaps, implying that including understudied pools such as bamboo rhizomes may lead to systematic improvement of mitigation potential [
69,
70].
For bamboo systems, this issue is especially important. Moso bamboo forests were estimated to account for up to 5.9% of China’s total forest carbon stock by 2008, and regional carbon sink contributions from bamboo forests in Zhejiang increased from 18 to 34 million tons over recent inventory periods, highlighting their growing significance in climate mitigation strategies [
71,
72]. Yet prevailing accounting frameworks rarely distinguish bamboo rhizomes as explicit carbon pools, instead subsuming them within generic BGB categories, thereby undervaluing their dynamic roles in storage, transfer, and regeneration [
12].
More broadly, these limitations matter because neutrality assessments are highly sensitive to assumptions about decomposition pathways, delayed emissions, system boundaries, and product lifecycles. Debates in forest bioenergy research have already shown that carbon neutrality claims can be distorted when deadwood persistence or delayed emissions are insufficiently represented [
73,
74]. Notably, the achievable potential for forest carbon storage is becoming increasingly constrained by rising disturbance and uncertainty, which makes fast-growing bamboo systems with resilient rhizome networks particularly relevant as nature-based climate solutions during the rapid-reduction and deep-decarbonization phases of carbon neutrality pathways [
75,
76]. Carbon neutrality roadmaps should therefore integrate both the underestimated persistence of stump-derived carbon and the dynamic cycling of bamboo rhizomes, so as to avoid structural undercounting and to better align carbon accounting with policy design, carbon markets, and ecosystem-based mitigation strategies.
7 Conclusions and Future Directions
7.1 Conclusions
This review shows that tree stumps and bamboo rhizomes represent fundamentally different belowground carbon pools, not only in biological status, but also in the ecological processes through which they influence carbon storage, emission, and persistence. Tree stumps are mainly embedded in dead organic matter dynamics, where carbon is retained through structural persistence and emitted through decomposition and partial transfer to soil organic carbon. Bamboo rhizomes, by contrast, remain part of a living belowground system that supports storage, redistribution, regeneration, and stand renewal. Their contribution to carbon sequestration therefore depends not only on biomass stock, but also on network integrity, clonal integration, and continued support for future culm recruitment and aboveground productivity.
The review further indicates that current accounting frameworks capture these two pools unevenly. Stump pools, despite substantial uncertainty in decay rates, decay-class transitions, and localized fluxes, can generally be accommodated within dead organic matter accounting. Bamboo rhizomes, however, remain more fundamentally underestimated because their living, clonal, and process-dependent roles are insufficiently represented within current belowground accounting logic. When rhizomes are merged into generic BGB categories, accounting approaches may capture part of the stock while failing to represent the functions that regulate regeneration, persistence, and long-term carbon balance in bamboo systems.
Thus, there is an urgent need to shift from stump-compatible static residue logic to a rhizome-focused framework for carbon accounting in bamboo systems. Such a framework should distinguish living rhizome networks from dead organic matter, incorporate process-based belowground functions, and extend accounting boundaries from in-stand pools to post-harvest pathways and the fate of residual belowground structures. Doing so would improve carbon accounting and strengthen the role of bamboo systems in broader climate mitigation strategies and carbon neutrality assessments.
7.2 Perspective on rhizome-focused carbon accounting
Given the fundamental differences between bamboo rhizomes and tree stumps in biological status, ecological function, and carbon-cycling pathways, we propose the following directions for future research and application.
D1: future studies should improve the direct quantification of bamboo rhizome biomass, turnover, structure, and connectivity, while also linking these measurements to functional indicators such as non-structural carbohydrate transfer, clonal integration, respiration, and regenerative support under contrasting environmental and management conditions. Advances in ground-penetrating radar, tracer approaches, and integrated field measurements might potentially provide an important starting point for differentiation, but they need to be coupled more explicitly with process-based indicators rather than being used only for static biomass estimation.
D2: future work should move beyond a predominantly Moso bamboo perspective and test whether the rhizome-focused framework generalizes across bamboo growth forms, phylogenetic groups, and management systems. This review suggests that rhizome function, biomass allocation, and carbon residence vary among monopodial and sympodial bamboos, as well as across climatic and edaphic settings. Before generalized accounting factors or reporting protocols are adopted, a stronger comparative basis is needed across monopodial bamboos (e.g., Phyllostachys), sympodial bamboos (e.g., Bambusa and Dendrocalamus), and regions.
D3: future accounting frameworks should better resolve how rhizome degradation, disturbance, and management alter not only BGB, but also the long-term stability of soil carbon and stand-level sequestration trajectories. This will be especially important for identifying the threshold at which bamboo systems shift from efficient and resilient carbon sinks to unstable carbon pools or even carbon sources. Such thresholds are likely to depend not only on biomass loss, but also on disruption of resource redistribution, regeneration failure, and delayed belowground carbon emission.
D4: future studies should explicitly consider the temporal transition of rhizomes across accounting states. Rhizomes function as living carbon-regulating networks during stand persistence, but after harvest, disturbance, or severe degradation they may partly transition toward residual belowground necromass and delayed decomposition pools. Future frameworks should therefore track when and how rhizomes shift from living regulatory pools to decomposing residues, because this transition provides an important conceptual and operational bridge between bamboo rhizomes and the stump comparison developed throughout this review. Without this temporal perspective, the distinction between stump carbon and rhizome carbon remains conceptually clear but operationally incomplete.
D5: future bamboo carbon assessments should adopt broader system boundaries that integrate in-stand storage with post-harvest residence time, durable products, recycling pathways, and the fate of residual belowground structures. Existing evidence suggests that the climate value of bamboo can be underestimated or overstated when analyses stop at standing biomass. A fuller accounting chain should therefore connect living rhizome processes, harvested culm pathways, residual rhizome persistence, and delayed emissions after harvest or degradation.
D6: an important next step will be to integrate ecosystem-based carbon accounting with LCA. Although LCA has already been applied to bamboo products, it is still only weakly connected to the living belowground processes emphasized in this review. Future research should therefore link rhizome-mediated in-stand carbon dynamics to harvested biomass pathways, product longevity, processing emissions, substitution effects where relevant, recycling, and end-of-life emissions. Without such integration, the climate value of bamboo systems may continue to be assessed using boundaries that are too narrow to capture either their full mitigation benefits or their trade-offs.
D7: future studies should pay greater attention to uncertainty propagation and the applicability of measurement, reporting, and verification (MRV). If bamboo rhizomes are to be represented more explicitly in inventories, carbon markets, or policy-facing mitigation assessments, ecological understanding will need to be translated into measurable, reportable, and verifiable indicators. This includes uncertainty in rhizome biomass estimates, turnover rates, species-specific allometry, degradation effects, process-based proxies, and post-harvest carbon residence. In this sense, improving bamboo carbon accounting will require not only better ecology, but also clearer reporting logic and stronger uncertainty treatment.
Overall, future progress will depend not only on improving measurement precision, but also on aligning accounting logic with the distinct biological and ecological identity of the carbon pools being measured. For tree stumps, this largely means improving parameterization within an already recognizable dead organic matter framework. However, for bamboo, it means moving beyond generalized belowground categories towards a framework that explicitly recognizes rhizomes as dynamic living carbon pools whose ecological significance lies in storage, redistribution, regeneration, and their coupling with longer-term soil and post-harvest carbon pathways. Formally addressing this distinction may be critical to improve the accuracy of carbon accounting mechanisms, whilst enhancing the robustness of biogeochemical model projections of terrestrial carbon dynamics under current and future climate scenarios.
The Author(s) 2026. This article is published by Higher Education Press.
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