With the development of management practices of modern enterprise, the practice of human resource management in enterprises is becoming more and more diversified, and the human resource management activities are no longer limited to the responsibility of the Human Resources Department. In order to realize the effective management of human resources, the Human Resources Department must cooperate with the managers of other departments to accomplish the management activities together. For non-human resources departments, Department Managers, Line Managers, especially FLMs, shall shoulder the supervisory responsibility of transmission and implementation.
Many scholars believe that the implementation of human resources management activities by FLMs is the first step for enterprises to achieve the human resource management effectiveness (Lowe, 1992; den Hartog, Boselie & Paauwe, 2004)   . Compared with the Human Resource Department, the cognition, understanding and implementation of human resource management by FLMs have greater influence on staff. Advanced human resources management concepts, policies, systems and activities, if the FLMS can not effectively transfer and operate, are also equivalent to a paper empty talk. So from this point of view, the FLM HRM implementation is directly related to the effectively landing of enterprise human resources management. Therefore, this paper will review the human resource management function of the FLM from the perspective of human resource management, and give some directions for the future research of the field.
2. Front Line Managers (FLMS)
Front Line Managers (First line manager, FLMs), refer to those who contribute directly to the achievement of organizational objective generally in product field (production, operation and manufacturing) (Heraty & Morley, 1995)  . Storey (1988) divided Line Managers into two broad categories according to management authority: Junior/Middle Line Managers and Senior Line Managers, of which Junior/Middle Line Managers are the FLMs  . McGovern, Gratton and Hope Hailey et al. (1997) believe that the FLMs are the people who are not human resource manager with the responsibility of managing staff regardless of the level of the job  .
With the deepening of the study, scholars further define and explain the FLMs. Hales (2005) believes that FLMs are typical role of frontline management, which undertakes the communication with first-line staff (i.e., those who do not possess management functions) and is responsible for receiving the staff’s work report  . Nehles et al. introduced the human resources management effectiveness in 2006, and believe that FLMs are junior managers who are responsible for managing daily operation of basic team and certain human resources  . FLMs are direct managers of product and service from the perspective of product and service; and they play a center role in the management of organizing operation and are responsible for the product and service as well as performance of their team.
The product development and production of enterprises show a fine trend of development, and the structure of enterprises is becoming more and more flat due to the market competition. As the role of FLMs is more and more important, the role and responsibilities of FLMs played and undertaken in the enterprise is more and more irreplaceable.
3. Human Resource Management Responsibility of FLM
The First Line Manager is between the ordinary staff and the middle-senior managers in the organization, in charge of directly leading, commanding and controlling the work of the ordinary first line staffs. The specific roles and responsibilities undertaken by the First Line Manager at different times are also different. Li Weidong, Liu Hong and Wang Yufeng (2010) have summarized the roles and responsibilities  undertaken by the First Line Manager at different times, as shown in Table 1.
It is easy to know that since the beginning of the last century, the FLMs have been playing the role of a task bridge between the first line staffs and higher senior managers, in charge of conveying the information and managing the employees. Storey found that the work of the First Line Manager actually includes nine human resources functions including reward, cultivation & training, motivation of teams, evaluation of subordinates, vocational training, expense cutting down, improvement of quality, customer service, continuous improvement and optimization of the labor force allocation as early as 1992, and Storey suggests that the First Line Manager shall be given more tasks for human resource management  .
After interviewing 667 managers in 2006, Kulik and Bainbridge put forward the detailed division of labor between the First Line Manager and HR in the human resource management process: the development of promotion decision, performance management, guidance and standardization of staff’s behavior, work design, career planning, recruitment and selection of staff as well as the development of successor program are the human resources management undertaken by First Line Manager; while the management of salary and welfare, the planning of human resources, the development of leadership, the creation of organizational culture and the training of staff are the key work of HR  .
The Human Resources Department is responsible for developing the effective human resource practices for enterprises. However, how these practices are
Table 1. Roles and Responsibilities of the First Line Manager.
Data source:  .
achieved ultimately falls on the company’s First Line Manager. Through the empirical research on the First Line Manager, Perry and Kulik (2008) have put forward that while retaining the original traditional Human Resources Department, more and more enterprises will gradually transfer the function of human resources management to the First Line Manager in each department, who truly implements the human resources decisions, truly contacts, deploys and manages the HR. It is found in the research by two scholars, Perry and Kulik that the effect of devolution is significant and is positively regulated by the first line support  . Zhang Chuanqing and Tian Xu’s empirical study in 2012 shows that the participation of the First Line Manager in activities for human resource management has played a regulatory role in the behavior of staffs and the behavior of organizational citizenship. The scholars, Alfes, Truss and Soane et al. (2013) have constructed the behavior of the FLMs, human resources management practices and model of individual performance perceived by the staff from the view perceived by staffs and in accordance with the social exchange theory, and have analyzed 1796 interviewees through structural equation model, the result of which shows that the First Line Manager has an important significance in human resources management effectiveness: the scholars, Alfes et al. (2013) think that the focus of human resources management shall be on selection of the First Line Manager, resource allocation and performance management, followed by the support for the First Line Manager to ensure the fair and consistent human resource management practices  .
4. Restrictions on FLMs in Human Resource Practices
As FLMs show better performance than HR Department in some HR work, such as recruitment training, performance management and promotion design, etc., part of the HR work are transferred to the FLMs to manage and execute, which is also one of the options for enterprises to reduce cost, expand influences, improve effects and efficiency (Brewster & Holt Larsen, 2000; Kulik & Bainbridge, 2006)   . However, such HR devolution is not always welcomed and recognized by FLMs, because they are in a complex working environment, and the devolution of HR work has increased the work diversity of the FLMs, which is not necessarily expected by them. (Sims & Szilagyi, 1976)  .
In the 1992 study, Storey ever proposed two core dimensions-initiative/passivity, business orientation/technology orientation, which can be used to distinguish different types of FLMs, and presented the Storey model as shown in Figure 1. In this model, Storey thought that: Personnel Department is not the key to improve the work of FLMs, because there are more passive FLMs than the initiative FLMs in most enterprises  .
Whether the FLMs can execute the human resource task well, and the formal incentive methods or means of enterprises (McGovern, et al., 1997)  . In addition, there are many problems between FLMs and HR Department that affect the human resources management work undertaken by FLMs: FLMs do not like
Figure 1. Storey model line manager type division. Data source: Storey, J., Developments in the Management of Human Resources, Blackwell, Oxford, 1992.
bureaucracy and institutionalization formed in the process of human resource management (Gratton L, et al., 1999)  ; while the HR Department thinks that FLMs do not perform well in carrying out performance assessment on staff (Redman, 2001)  . In addition, in reality, many FLMs of enterprises especially the team leaders, are promoted from the non-management staff (first line staff), and they will still lack the necessary awareness of the specific activities arranged by the HR Department when they face the specific practical work at micro level of enterprise every day.
Many scholars have proposed the restriction factors on the FLMs in execution of human resources work from different standpoints. Bond and Wise (2003) argue that the human resources executive efficiency of FLMs is influenced by the relevant policies and procedures developed by the organization  . Maxwell and Watson (2006), through a single case study, give the opinions that FLMs are affected by factors such as work overload, conflict of roles, lack of time, insufficient support from HR Department and insufficient HR skills trainings and so on in execution of human resources management activities  . Nehles, Terhalle and van Riemsdijk et al. (2010), through multiple case studies, give the opinion that, the FLMs are restricted and constrained by the factors such as ability, competencies, self-expectation, human resource support, and policy procedures in the human resources practical efficiency  . Den Hartog, Boon and Verburg et al. (2013), through the study of 2063 staff and 449 managers in 119 branches of a large enterprise, found that the communication skills of FLMs play the role of positive regulation on the relation between the human resource management activities at the level of FLMs and that at staff level  ; strong communication skills will strengthen the relation between the human resources management activities at two levels. Southall (2014), based on the social exchange theory and job demand theory, developed study on the discretion and found that the discretion of FLMs in the execution of human resources management activities is centered on the job demand, and through the staff’s response to job involvement and innovative behaviors, the exchange process is influenced  . Huang Zhaoyou (2015) argue that the FLMs are not the professional management personnel in HR Management Department, for which they will be restricted in the development of human resource management efficiency, and the restriction factors include the lack of FLMs’ abilities, lack of impetus and limited participation chance.
To sum up, after several years’ development, the study of FLMs from the human resources management aspect involves different fields and forms multiple theoretical systems. And in the existing studies of the correlation between FLMs and human resource management, scholars still have various opinions and do not form a unified point of view yet. And between the FLMs and HR Department, there are still many restriction factors.
5. Improvement of Human Resources Management Effectiveness of FLMs
With the increasing awareness of the relationship between FLMs and human resource effectiveness, scholars begin to discuss how to promote the improvement of human resource effectiveness of FLMs. Surveying present research conditions, the exploration is carried out in two ways.
Kuvaas, Dysvik and Buch (2014), based on the AMO model, believe that the organization can improve the ability, motivation and opportunity of FLMs in the aspects of human resources via a series of strategies such as business support and training to enhance the feasibility of performing human resource management activities (Bos-Nehles, van Riemsdijk, & Looise, 2013)  . Different from AMO research perspective, domestic scholars mainly focus on how to effectively enhance the effective support and cooperation of human resources management activities performed by the Human Resources Department to the FLMs. Liu Xiangyang (2015), from the perspective of cooperation theory, established the cooperation model between FLMs and personnel in Human Resources Department for purpose of exploring the impact of cooperation relationship among then on the human resources management effectiveness, and introduced the cooperation satisfaction as the metavariable. The research results show that the better the foundation of cooperation relationship between FLMs and personnel in HR Department shown in the competency of human resources practices is, the better the cooperation willing is, the higher the degree of trust in the cooperation is, the more smooth the communication is, the stronger the dependency of each other is, and the higher the human resources management effectiveness is; and the cooperation satisfaction has some mediating effect between cooperation relationship and human resource management effectiveness  . Chen Ci (2016), based on the collaborative management theory, established the collaborative process model for human resource management of FLMs and HR Department for purpose of exploring the relationship between communication, trust, dependency and cooperation and human resources management effectiveness in the process of collaboration, and found by research that if there is smooth communication, higher degree of trust, higher dependency and close cooperation among them, the human resources management effectiveness of FLMs is more higher  .
6. Directions for Future Research
The researches show that there is hardly any research on FLMs in human resources management based on quantity of literatures and research point. Especially in the field of empirical research, the previous literature in this field is not discussed comprehensively and thoroughly. Given this, we believe that the research of FLMs in human resources management can be discussed in theory and empirical study from the following aspects:
1) With the HRM role positioning more and more strategic orientation, the FLMs’ perception of the importance &effectiveness on HRM will change. For example, more and more enterprises are beginning to reconstruct the HRM system, transforming it from the original traditional HR department to HR-COE (Human Resource Expert Center), HR-SSC (Human Resource Sharing Service Center) and HRBP. Future research can focus on FLMs’ perception of HRM from a dynamic perspective and the impact of this perception on their attitudes, behavior, and HRM performance.
1) In the current study, this trend of the HR devolution has been widely noticed. But the impact of the FLMS’ HRM responsibility on HRM performance (positive or negative) has not yet been answered. Through the summary of past studies, we believe that there may be a “double-edged sword” effect. On the one hand, FLM can make rapid adjustments in the implementation process which improves the implementation of HRM effect.. On the other hand, taking on additional roles may also take up the line manager’s more resources, which will not only prevent the line manager from effectively implementing the HRM activity, but will even have a negative impact on his or her job and performance. Future research can do more in-depth exploration on the impact of HR devolution.
3) The boundary conditions related to the effect of HR devolution are not adequately addressed. The nature and extent of the impact of this trend may also be different in different organizational contexts. It is important to clarify this issue for theory and practice, and that future research should continue to excavate its boundary conditions.
The paper arranges the research status of human resources management function of FLMs from the perspective of human resources management. First, we review the definition of front-line managers and then summarize Human resource management responsibility of FLM. FLMs are affected by a number of factors in the implementation of human resource management practices. Realized it, scholars did some research about how to promote the improvement of human resource effectiveness of FLMs. Although Scholars have done a lot of research in this field, there are still some uncertain factors, so we sum up some of the future research directions and hope to help later research.