Introduction

Megacity regions (MCRs) hold a preeminent position in global economic development, as they prompt the agglomeration of advanced economic activities, high-skilled labour, well-equipped infrastructure, and extraordinary governance capacity (Hall and Pain, 2006; Wu, 2016; Scott, 2019; Phelps et al., 2023). MCRs are territorial entities that embrace the most intensive industrial dynamics for industrial upgrading and fostering emerging industries, which are largely fuelled by technological innovation and entrepreneurship (Feldman et al., 2015; Yeh and Chen, 2020; Xu et al., 2024). Nascent and diversified economic activities occur mainly in MCRs, whereas routinised and repetitive jobs tend to disperse towards peripheral locations (Duranton and Puga, 2000; Yang and Chan, 2023).

Functional polycentric MCR development performs as an efficient spatial organisation for refining the industrial division of labour, magnifying agglomeration externalities, and uplifting economic competitiveness (Hall and Pain, 2006; Burger and Meijers, 2012). Existing studies adopted various types of indicators, including traffic flows (Liu et al., 2016; Hui et al., 2020), commuting flows (Zhang et al., 2020; Chen and Yeh, 2022), intra-firm organisations (Hoyler et al., 2008; Chong and Pan, 2020), and inter-firm linkages (Yeh et al., 2015; Pan et al., 2017), to decipher polycentric development within and beyond MCRs. Intra- and extra-regional spatial patterns and functional polycentricity of MCRs as open systems have been examined across the globe (Taylor et al., 2008; Zhang and Kloosterman, 2016; Li and Phelps, 2018; Ma et al., 2021; Zhang et al., 2025). However, against the backdrop of growing uncertainties in global economies owing to intensifying interest conflicts between leading economic powers and the COVID-19 pandemic, the drivers and stakeholders that underpin polycentric MCR development have become increasingly volatile. On the one hand, geopolitical conflicts have led to trends of de-globalisation, which facilitate the exodus of traditional industrial forces and the shrinkage of foreign direct investments (Gong et al., 2022; Yeung, 2023). On the other hand, indigenous technological innovation pressed by external risks and empowered by the new wave of technological revolution can bolster the emergence of new industries (e.g., biotechnology, artificial intelligence, new energy, new material, etc.) as pioneering economic forces in MCRs (Zhang and Wu, 2019; Yu et al., 2022; Xu et al., 2024).

However, existing studies on MCRs remain inadequate in tracing emerging ‘real-world’ economic dynamics initiated by heterogeneous agents over the past decade. First, indirect indicators, such as intra-firm organisations, inter-firm linkages, and other economy-related proxies, can barely capture the role of supply-demand economic dynamics in shaping polycentric MCRs. In an increasingly turbulent world alongside de-investment and re-investment, ‘real-world’ economic transactions can advance our understanding of grounded and dynamic polycentric MCR development (Hanssens et al., 2014; Yeh and Chen, 2020; Ma et al., 2022). Second, standard industrial classifications, such as manufacturing and services, can hardly generate accurate insights into polycentric MCR development. Emerging high value-added economic dynamics, such as the complex interactions between high-tech industries and knowledge-intensive producer services in MCRs, should be considered as vital agents and associated ‘space of flows’ (Ma et al., 2022; Yu et al., 2022; Zhang et al., 2022; Schiavone et al., 2022). Third, on top of relational linkages, the ‘space of flows’ initiated by micro-level heterogeneous economic agents that nuance the understanding of polycentric MCR development should be incorporated into the research framework, as economic agents are not homogeneous but becoming increasingly heterogeneous in attributes and networking capabilities in the present-day techno-economic context (Zhang, 2018; Shearmur and Doloreux, 2021; Xu et al., 2024).

This study attempts to fill the research gaps by delineating polycentric MCR development based on intra- and extra-regional economic transactions between emerging high-tech industries and different types of producer services as heterogeneous economic agents via a case study on the Guangdong–Hong Kong–Macao Greater Bay Area (‘GBA’ hereafter) in China. Intra- and extra-regional economic transactions between emerging high-tech industries in Shenzhen and Dongguan and producer services across the country operate as grounded economic forces that contribute to functional polycentric MCR development. Economic transactions between emerging high-tech industries and producer services facilitate industrial upgrading, refine ongoing spatial divisions of labour, and underlie the regional competitiveness of MCRs. Furthermore, this study scrutinises the role of various types of producer services across the country that serve emerging high-tech industries in Shenzhen and Dongguan in polycentric MCR development. Through zooming in on ‘real-world’ economic transactions initiated by heterogeneous economic agents in the GBA, this study seeks to enrich and nuance the understanding of functional polycentric MCR development in developing economies under the new techno-economic context.

The remainder of this paper is organised as follows. Section ‘Literature review’ revisits the pertinent literature on polycentric MCR development and intra- and extra-regional linkages between high-tech industries and producer services. ‘Research design’ presents the case selection, data sources, and methodology. The empirical work consists of two sections. Section ‘Functional polycentricity of the GBA from intra- and extra-regional linkages between emerging high-tech industries and producer services’ delineates the polycentric MCR development of the GBA through intra- and extra-regional economic transactions between emerging high-tech industries in Shenzhen and Dongguan and producer services across the country, and Section ‘Functional polycentricity within and beyond the GBA nuanced by various types of producer services’ probes into the role of various types of producer services in nuancing the understanding of polycentric MCR development of the GBA. Section ‘Discussion and conclusions’ discusses the research findings in a broader theoretical discourse and concludes the study.

Literature review

Dynamic functional polycentricity of unbound MCRs

Intra- and extra-regional polycentricity of MCRs

Since the 2000s, city-regionalisation has been geographically pervasive across developed and developing countries amidst planetary urbanisation and economic globalisation (Scott, 2001; Xu and Yeh, 2011; Brenner and Schmid, 2014; Wu, 2016). A plethora of terminologies have surfaced to capture the ‘new form of urbanisation’, such as ‘global city-regions’ (Scott, 2001), ‘MCRs’ (Hall and Pain, 2006), ‘urban agglomerations’ (Fang et al., 2010) and ‘super MCRs’ (Yeh and Chen, 2020). The influential ‘POLYNET’ project, supported by the European Regional Development Fund, to examine the formation and development of eight MCRs in Northwest Europe (Hall and Pain, 2006) consistently used the term ‘MCR’ to unravel emergent city-regional development.

Polycentricity has been broadly acknowledged as an effective pattern of spatial organisation that can improve the economic competitiveness of MCRs (Meijers, 2008; Ma et al., 2021), facilitate social cohesion (Hui et al., 2020; Zhang et al., 2020), and enhance environmental sustainability (Liu et al., 2016; Zhang et al., 2025). Polycentricity manifests morphologically or functionally (Burger and Meijers, 2012). Morphological polycentricity is measured by traditional urban system ways of thinking, which use attributes (e.g., economic output and population scale) and size ranking to indicate the absolute importance of cities. By contrast, functional polycentricity, inspired by Castells’ (1996) ‘space of flows’ theory, adopts relational ways of thinking to determine the relative importance of cities by calculating their interactive intensity. Owing to increasingly intensive intercity interactions and interdependency, functional polycentricity gained momentum in the past decade for deciphering polycentric MCR development (Hoyler et al., 2008; Hanssens et al., 2014; Liu et al., 2016; Li and Phelps, 2018; Ma et al., 2022; Zhang et al., 2022; Pan et al., 2024).

Meanwhile, functional polycentric MCRs have become increasingly unbound, moving beyond the regional scale due to intensified global linkages or state-rescaling endeavours (Taylor et al., 2008; Li and Phelps, 2018; Li et al., 2023). Previous studies examined the functional polycentricity of MCRs at the regional scale and regarded regions as physical territories with fixed boundaries in space (Burger and Meijers, 2012; Liu et al., 2016). Recognising MCRs as open systems constructed by socioeconomic relations across different scales, urban scholars underwent a progressive transition to examine functional polycentricity within and beyond MCRs. For example, Taylor et al. (2008) employed the interlocking network model to examine polycentricity in eight MCRs at the regional, national, European, and global scales, observing that the different scales offer distinctive scenarios and policy implications for MCR polycentricity. Li and Phelps (2018) examined the functional polycentricity of the Yangtze River Delta region in China at multiple geographical scales based on intercity knowledge collaboration, revealing that the degree of functional polycentricity decreases when the geographical scale expands. Li et al. (2024) investigated regional functional polycentricity in Germany and reported that the role of MCRs in promoting economic growth and minimising regional disparities varies across different spatial scales. As Taylor et al. (2008: 1080) rightly pointed out, ‘[p]olycentricity is sensitive to the geographical scale of the operations being studied.’ MCRs may be regarded as being unbound when scrutinising functional polycentricity engendered by relational ‘space of flows’ in the globalising world to capture the intra- and extra-regional linkages for MCR development.

Indicators and measurements of polycentric unbound MCRs

Various indicators—specifically, a broad spectrum of relational datasets focusing on intercity flows—have been utilised to assess the polycentricity of MCRs. The Globalization and World Cities Research Network transformed the theoretical frameworks of Sassen (1991) and Castells (1996) into an operationalizable research framework through a focused examination of intra-firm organisational linkages across cities through office distribution within key producer service specialisations in global and regional contexts (Taylor et al., 2008; Bassens et al., 2024). In follow-up scholarly efforts, other categories of ‘space of flows’ that configure the polycentricity of MCRs, including traffic volumes (Liu et al., 2016; Hui et al., 2020), infrastructure construction (Li et al., 2023), commuting flows (Zhang et al., 2020; Chen and Yeh, 2022), and organisational linkages of manufacturing activities (Zhao et al., 2017), were examined. Recently, under the trend of knowledge intensification and technological revolution in MCRs worldwide, studies around intercity knowledge flows, proxied by co-publication and co-patenting, surged for updating the understanding of polycentric MCR development (Li and Phelps, 2018; Ma et al., 2022; Wang and Meijers, 2024).

With regard to measurements, functional polycentricity is commonly evaluated ‘based on an analysis of the relative intra-regional balance of internal centrality’, as well as external centrality from a multiscalar perspective (Burger and Meijers, 2012; Liu et al., 2016: 1305; Ma et al., 2021; Li et al., 2024). Existing studies generally adopted the definition of polycentricity from Green (2007) to measure the degree of functional polycentricity by calculating the regional balance of cities’ importance in terms of their relational assets (Hoyler et al., 2008; Hanssens et al., 2014; Liu et al., 2016; Zhao et al., 2017; Ma et al., 2022). Similar measurements are employed to determine external centrality within a wider geographical coverage, such as at the national or global scale (Burger and Meijers, 2012; Li and Phelps, 2018; Zhang et al., 2022).

Inadequacies in capturing economically grounded polycentric MCR development

However, existing research progress has been criticised for inadequately capturing economically grounded polycentric MCR development (Hanssens et al., 2014; Li and Phelps, 2018; Wang and Meijers, 2024). First, neither intra-firm organisational linkages nor various proxies of intercity ‘space of flows’ can substantially mirror ‘real-world’ economic activities connecting cities within and beyond MCRs (Hanssens et al., 2014; Yeh et al., 2015; Zhao et al., 2017). The spatial flows of production factors (e.g., labour, capital, and knowledge) can hardly convince functionally polycentric MCR development without considering the actual supply and demand of economic activities under evolving spatial divisions of labour. Second, intercity flow indicators should keep pace with economic dynamics in MCRs, especially the emergence of knowledge-intensive industries vital to enhancing regional competitiveness and refining the spatial division of labour (Zhang, 2018; Yu et al., 2022). Emerging high-tech industries, driven by the new wave of technological revolution, and knowledge-intensive producer services are nonetheless the underpinnings of the present-day polycentric MCR development (Yeh and Chen, 2020; Shearmur and Doloreux, 2021; Zhang et al., 2022; Xu et al., 2023). Third, assets (e.g., goods, information, capital, knowledge) that fill out the ‘space of flows’ have been overemphasised at the expense of the role of micro-level heterogeneous economic agents initiating the flows (Zhang, 2018; Xu et al., 2024). Specifically, economic agents contributing to polycentric MCRs are heterogeneous in their attributes, resource accessibility, and networking capacity. Thus, focusing on relational assets whilst ignoring micro-level heterogeneous agents as network creators may fall short of gaining a nuanced understanding of polycentric MCR development. Therefore, MCR scholars have been appealing for absorbing theoretical insights from economic geography to interrogate micro-level heterogeneous economic agents (e.g., emerging high-tech industries and knowledge-intensive producer services) that seek market profits, initiate grounded economic transactions, and thus refine the spatial division of labour within and beyond MCRs.

Economic linkages between high-tech industries and producer services

Intra- and extra-regional linkages between high-tech industries and producer services

Producer services spun out of industries due to flexible specialisation and vertical disintegration in response to the rapidly changing and increasingly uncertain market during the transformation from Fordism to Post-Fordism in the 1980s (Piore and Sabel, 1984). Providing intermediary specialised inputs for R&D, technology transfer, finance, law, accounting, advertisement, and trade, producer services were not considered independent from industrial sectors (Daniels and Bryson, 2002). The emergence of local and regional industrial complexes was attributed largely to the early-stage development of producer services as affiliations to industries, as the latter tended to avoid business risks and reduce the cost of non-core activities when facing progressively customised market demands (Keeble and Nachum, 2002).

Since the 2000s, however, the geography of economic linkages between industries and producer services has transitioned from local and regional complexes to both intra- and extra-regional networks (Strambach, 2008; Lüthi et al., 2010). For one thing, producer services gradually became an independent, energetic, and professional economic sector under increasingly fierce competition, serving industrial activities for technological innovation and market expansion (Muller and Zenker, 2001). They were disposed to choose business locations more freely in pursuit of agglomeration economies and market accessibility, preferably concentrating in large cities atop the urban hierarchy (Shearmur and Doloreux, 2008; Yang and Yeh, 2013). In addition, the revolutionary development of digital technologies has made long-distance knowledge exchange and business transactions attainable. Thus, producer services can serve intra- and extra-regional industrial clients, as long as they exhibit exceptional professionalism and ride on digitalised knowledge-transfer channels (Shearmur and Doloreux, 2015b; Bassens et al., 2024). In recent years, producer services have embraced digital business models to expand the industrial market through intertwining physical and virtual spaces, making geographical distance less consequential in economic transactions (Wood et al., 2020). Therefore, the proliferation of producer services has led to a geographical dispersion to small-and-medium-sized cities and even rural areas to lower operation costs and capture fragmented market segments (Shearmur and Doloreux, 2015a, 2021). In short, intra- and extra-regional economic transactions between high-tech industries and producer services show promise of functionally refining multi-scalar spatial divisions of labour, thereby uncovering economically grounded polycentric MCR development. Moreover, since high-tech industries are confronted with more complicated knowledge development, uncertain R&D exploration, venture capital injection, and high-risk market expansion, they are prone to strategically choose high-quality and trusted global producer services as economic partners (Yang et al., 2018; Xu et al., 2024). In contrast to industries in general, emerging high-tech industries more selectively demand the external provision of producer services within and beyond the region in which they are located.

Effects of linked high-tech industries and producer services for regional development

The positive effects of linkages between high-tech industries and producer services on regional development have reached a broad consensus. For producer services, serving high-tech industries can secure their business volume and employment, facilitate knowledge accumulation, and enhance technological professionalism (Vaillant et al., 2021). For high-tech industries, the injection of external specialised resources that are internally unavailable has been proven to raise firm-level productivity, market performance, and innovation vibrancy (MacPherson, 1997; Yang et al., 2018; Schiavone et al., 2022). The emergence of high-tech industries against the new wave of technological revolution urgently demands technology-oriented producer services to deepen R&D exploration, improve their financial capacity, and enable them to deal with legal, accounting, and market issues in nascent fields (Xu et al., 2024). Producer services ought to be more knowledge-intensive and thus tap into a persistently refining industrial division of labour according to the knowledge bases, such as P-KIBS and T-KIBS division, and services distinguished by specific technological domains, such as artificial intelligence and biotechnology (Pina and Tether, 2016; Schiavone et al., 2022). Therefore, producer services are essential for facilitating the emergence and development of regional high-tech industries, whilst emerging high-tech industries give fresh and valuable feedback to producer service providers within and beyond regions, which is beneficial for them to adapt to new techno-economic contexts (Content et al., 2022; Yu et al., 2022).

Well-connected high-tech industries and producer services lay the ground for regional development and competitiveness in a knowledge-based society. Linkages at the local and regional scales have been revealed to realise the creation of mutually reinforced high-tech industries and producer services as industrial complexes and, in parallel, refine the intra-regional industrial division of labour (Lüthi et al., 2010). Extra-regional linkages can strengthen geographically distant interactions between cities and regions, which can either generate knowledge-related resources to empower high-tech industries in destination regions or enhance the serving capacity to hinterlands to upgrade the quality of producer services in origin regions (Shearmur and Doloreux, 2015b; Schiavone et al., 2022). Overall, existing studies highlight that intra- and extra-regional linkages between high-tech industries and producer services can empower both ends, promote economic development in the origin and destination regions, and refine intra- and extra-regional divisions of labour.

Economic linkages between high-tech industries and producer services shaping functional polycentric MCRs

As mentioned previously, studies on functional polycentric MCRs paid insufficient attention to intra- and extra-regional linkages between emerging high-tech industries and producer services. Business transactions between the two entities represent grounded economic dynamics that can shape the functional polycentricity of MCRs against the new wave of technological revolution. Although studies on the effects of linkages between high-tech industries and producer services on firms, industries, and regions in economic geography have been well-progressed, their contribution to functionally polycentric MCRs remains less studied. Therefore, how ‘real-world’ economic transactions, which secure regional competitiveness and the ongoing refinement of intra- and extra-regional industrial division of labour, shape functional polycentric MCRs deserves to be unravelled, because functional polycentric MCR development cannot be detached from the periodical rise and fall of profit-seeking economic agents and ‘space of flows’ initiated by them (Hanssens et al., 2014; Zhang, 2018; Yeh and Chen, 2020; Xu et al., 2024).

By critically reviewing the relevant literature and theoretical debates, this study aims to fill these research gaps by marrying polycentric MCR studies and intra- and extra-regional linkages between emerging high-tech industries and knowledge-intensive producer services as heterogeneous economic agents to facilitate a more grounded understanding of functional polycentricity within and beyond MCRs.

Research design

Case selection

The GBA consists of nine cities in the Pearl River Delta (i.e., Guangzhou, Shenzhen, Foshan, Dongguan, Zhuhai, Huizhou, Zhongshan, Jiangmen, and Zhaoqing) and the two Special Administrative Regions of Hong Kong and Macao under the ‘One Country, Two Systems’ framework. The GBA is one of the economically leading MCRs in China, along with the Beijing–Tianjing–Hebei and Yangtze River Delta regions. Moreover, known as the region that went ‘One Step Ahead’ in China’s economic reform and opening up, the GBA has experienced rapid urbanisation, industrialisation, and tertiarisation (Vogel, 1989; Lin, 1997; Yeh and Chen, 2020; Xu et al., 2025). In the aftermath of the 2008 Global Financial Crisis, the GBA underwent economic transformation towards high-tech industries and knowledge-intensive producer services (Yang, 2020; Xu et al., 2023). Spatial restructuring progressed in parallel with economic transition, which led to the development of the GBA as a polycentric MCR in both morphological and functional manners (Zhang, 2018; Yeh and Chen, 2020; Hui et al., 2020; Zhang et al., 2024). Existing studies employed various indicators (e.g., commuting flows, traffic volumes, infrastructure connectivity, and intra-firm organisational linkages) to unravel the functional polycentricity of the GBA MCR (Yeh et al., 2015; Liu et al., 2016; Hui et al., 2020; Yeh and Chen, 2020; Zhang et al., 2020; Ma et al., 2022; Wang and Meijers, 2024; Xu et al., 2025). However, whether and how the region’s functional polycentricity is configured by intra- and extra-regional linkages via ‘real-world’ business transactions between emerging high-tech industries and producer services remains unaddressed.

Data and methods

Firm-level questionnaire survey and in-depth interviews

This study obtained the data from a first-hand firm-level questionnaire survey and in-depth face-to-face interviews conducted from January to May 2021. The firm-level questionnaire survey was carried out in Dongguan and Shenzhen, where a majority of high-tech industries in the GBA agglomerate (Yang, 2020; Yeh and Chen, 2020; Xu et al., 2023). Constrained by the accessibility to firms and relevant stakeholders under the COVID-19 pandemic, as well as time and financial constraints, high-tech firms in other cities in the GBA are not included in our study. A total of 363 high-tech industrial firms in the field of biomedicine and intelligent manufacturing participated in the survey and provided satisfactory information. In the survey, the high-tech firms were asked about the external producer services that they purchased between 2017 and 2019, such as the business transaction volume for each subsector (e.g., R&D-related services, professional services, financial services, and trade-related services) and the cities where they sourced the producer services. In addition to the questionnaire survey, 50 face-to-face in-depth interviews were conducted with key stakeholders (e.g., firm senior managers, government officials, industrial associations, and professionals), with an average duration of around 50 min. The interviews focused on why and how the high-tech industrial firms purchased producer services from certain cities to reveal the underlying forces behind the intra- and extra-regional linkages between emerging high-tech industrial firms and producer services.

Generation of city matrix

Based on our dataset from the survey conducted in Dongguan and Shenzhen, we only calculated the outdegree (i.e., service providing) as the nodal degree to indicate the cities’ producer service capacity for the GBA high-tech industries. Unlike other relations, such as transportation and commuting flows, that cover the outdegree and the indegree of all the sample cities, our survey merely covered the outdegree of all the cities in the GBA owing to funding and accessibility constraints during the COVID-19 pandemic. Nevertheless, Dongguan and Shenzhen can represent the agglomeration of the high-tech industries in the GBA to a certain extent, and the intra- and extra-regional linkages between the high-tech industries and associated producer services can delineate the functional polycentricity of the GBA under the emerging, as well as grounded, economic dynamics. Therefore, this study used the transaction volume between the high-tech industries and producer services to mirror the spatial linkages. The overall transaction value of each high-tech industrial firm is 1. The strength of the linkages is the sum of all the transaction volume between the high-tech industrial firms and the producer services. An asymmetric matrix of the cities with a business transaction value from transactions between the high-tech industries and the producer services was created for further analysis.

Measuring polycentricity

This study used the special functional polycentricity algorithm Green (2007) developed for the polycentricity evaluation. A variety of functional relations were measured and compared by using the following formula:

$${\rm P}{{\_}}{SF}(N)=(1-\sigma {{\_}}\partial )/\sigma {{\_}}(\partial \,\max )\cdot \Delta ,$$
(1)
$$\Delta =L/L{{\_}}\max ,$$
(2)

\({\rm{where}}\) ΡSF represents the functional polycentricity of a MCR, which ranges from 0 (total absence of polycentricity) to 1 (absolute polycentricity); \({\sigma }_{\partial }\) is the standard deviation of the nodal degree; \({\sigma }_{\partial \mathrm{max}}\) is the standard deviation of the nodal degree of a two-node network (\({{\rm{n}}}_{1}\),\(\,{{\rm{n}}}_{2}\)) derived from N, where \({d}_{n1}\,\)= 0, and \({d}_{n2}\)= the value of the node with the highest value in \(N\); and Δ represents the network density of the regional networks to ensure that the functional polycentricity falls to zero when no linkage/flow exists between the cities/nodes (Green, 2007).

The method used in this study was scalable (Green, 2007), meaning that functional polycentricity can be compared between intra- and extra-regional scales. In the next sections, this study compares the degree of intra- and extra-regional functional polycentricity, and that initiated by heterogeneous economic agents, namely, R&D services, professional services, financial services, and trade-related services, that serve the emerging high-tech industries in Dongguan and Shenzhen in the GBA.

Functional polycentricity of the GBA from intra- and extra-regional linkages between emerging high-tech industries and producer services

Functional polycentricity within the GBA

At the regional scale, intra-urban linkages between high-tech industries and producer services predominate in the area because most of Shenzhen’s and Dongguan’s outdegree comes from intra-urban instead of inter-urban transactions (Table 1). Although the survey only covers firms in Shenzhen and Dongguan, it can be found that the economic demands of high-tech industries for external producer services in the GBA are highly localised. This localised supply of producer services limits the intensity of intercity connections. It thus weakens the development of the functional polycentric MCR, in stark contrast to other types of ‘space of flows’, exemplified by intra-firm organisations, commuting flows, and infrastructural connectivity.

Table 1 Node outdegree and functional polycentricity in the GBA.
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In addition to local linkages, Hong Kong and Guangzhou stand out as two key cities in the GBA that provide specialised services to the high-tech industries in Shenzhen and Dongguan (Fig. 1). Hong Kong and Guangzhou have a similar intensity of connection to Shenzhen and Dongguan. However, apart from Hong Kong and Guangzhou, other cities exhibit a limited capacity to serve the high-tech industries in Shenzhen and Dongguan. This finding indicates that currently, only local linkages and connections between the central cities in the GBA play a part in constituting the regional complex of the high-tech industries and the producer services. In contrast, the second- and third-tier cities in the region engage in rather limited business transactions.

Fig. 1
Fig. 1
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Economic transactions between emerging high-tech industries in Shenzhen and Dongguan and knowledge-intensive producer services within the GBA. Source: Authors’ survey.

As a result, the degree of intra-regional functional polycentricity is 0.378. The low degree of functional polycentricity of the GBA derived from regional business transactions between the emerging high-tech industries and the producer services demonstrates that the grounded functional polycentricity of the GBA remains in its infancy. On top of intra-urban economic transactions, only a few central cities along the Guangzhou-Shenzhen-Hong Kong core axis are incorporated into the emerging intra-regional industrial division of labour. As a sales manager of an intelligent manufacturing firm in Dongguan put it, “today, most producer services I need can be sourced locally, and, more importantly, they save my searching cost and are more familiar with local business routines. I consider purchasing professional services from Guangzhou or Hong Kong only when no appropriate local service providers can meet my specific requirement.” (Interview with a sales manager of an intelligent manufacturing firm in Dongguan, 20 March 2021).

Functional polycentricity beyond the GBA

At the extra-regional scale, the degree of functional polycentricity increases to 0.679, which indicates that the level of polycentricity derived from economic transactions between the high-tech industries and the producer services increases along with the opening of the GBA regional system (Fig. 2). In the spatial linkages beyond the GBA, key nodes that serve the high-tech industries in Shenzhen and Dongguan concentrate primarily in the central cities in other MCRs in China, such as the Beijing–Tianjin–Hebei, Yangtze River Delta, and Chengdu–Chongqing Economic Zone, where high-quality producer service providers agglomerate. Although Guangzhou and Shenzhen are the primary cities possessing predominant intra-regional linkages, a larger number of central cities, such as Shanghai, Beijing, Suzhou, and Tianjin, in other MCRs are high on the list and surpass the second-tier cities (e.g., Zhuhai and Foshan) within the GBA (Table 2), giving rise to a more polycentric spatial pattern at the extra-regional scale. It illustrates that those extra-regional linkages with other central cities atop the national urban hierarchy function as even more critical sources that serve the GBA’s emerging high-tech industries.

Fig. 2
Fig. 2
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Economic transactions between high-tech industries in Shenzhen and Dongguan, and knowledge-intensive producer services beyond the GBA. Source: Author’s survey.

Table 2 Node outdegree and functional polycentricity within and beyond the GBA.
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A higher degree of functional polycentricity is observed when the intra- and extra-regional linkages between the high-tech industries and the producer services are considered. In the GBA and China, this pattern can be attributed to two major factors. First, a large proportion of transactions between high-tech industries and producer services take place at the intra-urban scale, instead of the intra-regional scale, owing to the relatively higher cost of transactions between different administrative entities and market segmentation under local protectionism and homogeneous economic structures (Wu, 2016; Yang et al., 2018). In other words, the industrial complex of emerging high-tech industries and producer services in the GBA in transitional China is still highly localised instead of regionalised. Second, only a limited number of central cities can serve emerging high-tech industries in the GBA, which implies that high-quality producer services are still spatially uneven in the economically leading MCR in China. Spatial spillover and dispersion of high-end economic activities from central to second-tier cities in the GBA have not been noteworthy. Functional polycentricity by the ‘real-world’ economic dynamics is geographically confined among central cities along the core urban axis. “Guangzhou and Hong Kong are two producer service centers we can partner with when we consider expanding the domestic or overseas market, respectively.” (Interview with a financial manager of an intelligent manufacturing firm in Dongguan, 19 March 2021). Third, knowledge-intensive producer services possessing a competitive service capacity and high service quality in China are geographically confined to central cities in MCRs atop the national urban hierarchy, presenting limited trickle-down effects yet (Yang and Yeh, 2013; Wang and Meijers, 2024). Therefore, the GBA can be regarded as an open regional system that mobilises and anchors national key producer service resources to empower high-tech industrial development. Complicated knowledge and high-value-added producer services are still spatially sticky in national first-tier cities in China, resulting in organisationally selective and geographically concentrated economic transactions between emerging high-tech industries and producer services. “Physical distance does not matter much for purchasing external producer services if we seek to acquire customized and quality-based solutions. In many instances, we must buy producer services from our suppliers who are specialised in our products.” (Interview with an international trade manager of an intelligent manufacturing firm in Dongguan, 5 March 2021).

Functional polycentricity within and beyond the GBA nuanced by various types of producer services

Polycentricity within the GBA nuanced by various types of producer services

Functional polycentricity is shaped by meso-level ‘space of flows’ and, notably, varies across different micro-level agents responsible for creating the linkages (Zhang, 2018). To gain a more nuanced understanding of polycentricity by economic transactions between high-tech industries and producer services within and beyond the GBA, this study further examines the role of different types of knowledge-intensive producer services that serve the high-tech industries in Shenzhen and Dongguan (Fig. 3). Producer services related to high-tech industrial development can be categorised into professional services (e.g., accounting and insurance), financial services (e.g., capital market and business banking), R&D services (e.g., research and design and commercialisation of research achievements), and trade-related services (e.g., trade agency and logistics) (Yang et al., 2018; Vaillant et al., 2021).

Fig. 3: Economic transactions between high-tech industries in Shenzhen and Dongguan and various kinds of knowledge-intensive producer services within the GBA.
Fig. 3: Economic transactions between high-tech industries in Shenzhen and Dongguan and various kinds of knowledge-intensive producer services within the GBA.
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a Professional services include legal, accounting,insurance, management consulting, and IT services. b Financial services include business banking and capital market services. c R&D services include research and design, technology transfer and commercialization, and intellectual property services. d Trade-related services include import/export trade, advertising, market research, testing, and digital commercial services. Source: Author's survey.

Within the GBA, professional services appear as the dominant catalyst for the polycentric development and exhibit the highest network density, followed sequentially by financial services, R&D services, and trade-related services. This empirical observation substantiates the strategic role of professional services, such as accounting and insurance, as spatial integrators in forging services provided by Hong Kong and Guangzhou with the demands of emerging high-tech industries in Shenzhen and Dongguan. It can be attributed to the function of Hong Kong and Guangzhou as a gateway for the overseas market and the domestic market, respectively. Professional services are generally associated with market orientation and tend to agglomerate in global cities. Although Hong Kong and Guangzhou play similar roles in providing financial and R&D services, the linkages created by economic agents are remarkably localised. Intra-urban linkages dominate the economic transactions between the high-tech industries and financial and R&D services, partially due to the fragmented administrative economies and the imperfect legal system, which may result in hesitation of high-tech industrial firms when partnering with external R&D service providers. Trust-based face-to-face interactions and geographical proximity are indispensable for sourcing external financial and R&D services as they are key factors underpinning the survival of emerging high-tech firms (see also Wang and Lin, 2018). In terms of trade-related services, it is repeatedly mentioned by stakeholders from our interviews that Hong Kong stands out as a remarkable ‘window’ for imports and exports owing to its unique status under the ‘One Country, Two Systems’ framework.

To summarise, the structural and nodal characteristics of intra-regional networks initiated by different types of producer services are somewhat dissimilar, largely due to disparate locational patterns of different types of producer services in the GBA, as well as the distinctive nature and corresponding territorial demands of their economic interactions with emerging high-tech industries.

Polycentricity beyond the GBA nuanced by various types of producer services

As for economic transactions beyond the GBA, the degree of functional polycentricity and network density forged by professional services retains the highest, followed sequentially by finance, R&D, and trade-related services (Fig. 4). The degree of extra-regional polycentricity by professional services is almost twice the value of that within the GBA, indicating that a greater number of cities beyond the GBA offer professional services to the emerging high-tech industries in Shenzhen and Dongguan. In contrast, financial and R&D service providers are disproportionally concentrated in national central cities, while trade-related services contribute to the polycentric development to a more limited degree at the extra-regional level. For example, Hong Kong, Guangzhou, Shanghai, and Beijing are state-designated national financial centres, while Beijing and Shanghai receive the lion’s share of national R&D resources in post-reform China (Zhang and Wu, 2019).

Fig. 4: Economic transactions between high-tech industries in Shenzhen and Dongguan and various kinds of knowledge-intensive producer services within and beyond the GBA.
Fig. 4: Economic transactions between high-tech industries in Shenzhen and Dongguan and various kinds of knowledge-intensive producer services within and beyond the GBA.
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a Professional services include legal, accounting,insurance, management consulting, and IT services. b Financial services include business banking and capital market services. c R&D services include research and design, technology transfer and commercialization, and intellectual property services. d Trade-related services include import/export trade, advertising, market research, testing, and digital commercial services. Source: Author's survey.

The extra-regional network configurations and different degrees of functional polycentricity can be explained by the uneven geographical distribution of producer serving capacity in the Chinese urban system to emerging high-tech industries in Dongguan and Shenzhen. In parallel, the divergent nature of extra-regional linkages between various types of producer services and emerging high-tech industries in transitional China also characterises the nodes and networks. As professional services are more intimately related to local tacit knowledge and norms in marketplaces, they are dispersed across different provinces in China due to the fragmentation and local protection of the domestic market. Although Hong Kong and Guangzhou occupy privileged positions in providing professional services, Shanghai, Beijing, Suzhou, Wuhan, and Hangzhou can also engage in the provision of competitive professional services to meet the demands of the high-tech industries in Shenzhen and Dongguan. These spatial linkages are not highly sensitive to physical distance but are inclined to direct towards market destinations. Spatially, high-quality financial and R&D services stick to a few national central cities (e.g., Beijing and Shanghai) with top-down state support inherited from the planning economy. The post-reform Chinese state holds a determining sway over establishing stock exchanges in Beijing, Shanghai, and Shenzhen, and centralising financial resources and regulations in the national central cities. Meanwhile, Beijing and Shanghai, as national scientific centres, surpass Guangzhou and Zhuhai as GBA cities in providing R&D services. A few other cities, such as Suzhou, Tianjin, Hangzhou, and Nanjing, also perform well in R&D producer service development. The state-led national urban hierarchy predominantly structures these spatial linkages. Moreover, trade-related services with export- or import-oriented nature tend to seek locations in coastal areas with international traffic accessibility, instigating a higher degree of intra-regional instead of extra-regional functional polycentricity. These spatial linkages hold certain locational preferences and are sensitive to transport costs and the international market.

In a nutshell, the empirical findings substantiate that micro-level economic agents serve as catalytic intermediaries in steering variegated functional polycentric configurations of MCR development through the identical channel of meso-level ‘space of flows’ between emerging high-tech industries and producer services (Table 3).

Table 3 Node outdegree and functional polycentricity shaped by various kinds of producer services within and beyond the GBA.
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Discussion and conclusions

With polycentric MCR development culminating as an open regional system, scholars are shedding light on not only intra- but also extra-regional polycentricity (Hoyler et al., 2008; Li and Phelps, 2018; Li et al., 2024). This study portrays the GBA as an open territorial entity and examines the functional polycentricity within and beyond the region. It echoes Peter Taylor’s point of view that functional polycentricity is sensitive to geographical scales (Taylor et al., 2008; see also Li and Phelps, 2018; Ma et al., 2021). Although a range of relational indicators and assorted intercity networks have been examined to decipher functional polycentric MCRs (Liu et al., 2016; Zhang et al., 2020; Hui et al., 2020; Chen and Yeh, 2022), ‘real-world’ grounded economic transactions upholding regional competitiveness and ongoing refinement of the spatial division of labour remain underexamined. Dissimilar indicators and networks may identify variegated functional polycentricity of MCRs. This study argues that the functional polycentricity shaped by ‘real-world’ economic transactions is valuable for enriching the grounded dynamics of polycentric MCR development and paving the way for regional planning implications.

Economic transactions between high-tech industries and knowledge-intensive producer services exert positive effects on both ends and involved regions (MacPherson, 1997; Shearmur and Doloreux, 2015b; Yang et al., 2018; Schiavone et al., 2022). Intra- and extra-regional linkages connected by economic transactions are conducive to refining the spatial division of labour and uplifting the level of functional polycentricity of networked regions. To this point, economic transactions between high-tech industries and producer services can be seen as emerging and grounded ‘space of flows’ to delineate functional polycentric MCR development. On top of meso-level ‘space of flows’, micro-level heterogeneous economic agents should not be neglected or homogenised in polycentric MCR development (Wang and Lin, 2018; Zhang, 2018; Xu et al., 2024). Possessing heterogeneous attributes and capabilities, economic agents’ distinctive locational preferences and network configurations embedded in institutional contexts further the understanding of polycentric MCR development. This study argues that various types of producer services serving high-tech industrial development perform as heterogeneous creators and shapers of ‘space of flows’ for functional polycentric MCR development contextualised in post-reform China.

This study draws several key conclusions. First, the functional polycentric MCR development of the GBA based on intra- and extra-regional economic transactions between the emerging high-tech industries in Shenzhen and Dongguan and the producer services across the country remains at a nascent development stage. The degree of functional polycentricity of the GBA shaped by this particular type of grounded ‘space of flows’ is lower than that examined by previous studies based on other relational indicators. Second, the degree of functional polycentricity of the GBA increases when upscaling from the intra- to the extra-regional level, which echoes with the scale sensitivity of polycentric MCR development. Third, the different types of producer services that cater to the demand of the emerging high-tech industries in Shenzhen and Dongguan play distinctive roles in underpinning polycentric MCR development within and beyond the GBA. Professional producer services induce the highest degree of polycentricity and network density, followed sequentially by financial services, R&D services, and trade-related services. The various types of producer services contribute to the functional polycentricity within and beyond the GBA to varying degrees and through distinguishable intercity network configurations, being primarily attributable to their differentiated location preferences across the post-reform Chinese urban hierarchy and the multifaceted nature of their spatial linkages with emerging high-tech industries.

This study attempts to enrich polycentric MCR research by unveiling the grounded economic transactions between emerging high-tech industries and various types of producer services as micro-level heterogeneous economic agents. However, on account of the limited accessibility of the survey under the COVID-19 pandemic, this study focused on only two emerging high-tech industrial sectors (i.e., biomedical and intelligent manufacturing) in Shenzhen and Dongguan in the GBA, which hinders the delineation of a more comprehensive and detailed landscape of polycentric development of MCRs. More second-hand relational datasets on grounded economic transactions are yet to complement first-hand questionnaire surveys and in-depth interviews. Forthcoming academic endeavours that employ grounded relational proxies to explore territorially open and functionally polycentric MCRs are promising, and persistent scholarly efforts around micro-level heterogeneous economic agents with contextual embeddedness should be incentivized to facilitate a more nuanced understanding of polycentric MCR development.