Abstract:     As the characteristics of multi-entities symbiosis and the cross-integration of business formats are intensified, it is difficult for enterprises to rely on the resources owned by a single alliance to achieve technological innovation. As a result, the innovation ecosystem has become an important way for enterprises to orchestrate resources. The innovation ecosystem consists of diverse populations, which can provide diversified innovation resources for enterprises, and promote the value-added of the ecosystem by matching the value proposition and coordinating the value co-creation behavior of the diverse populations. Although research on innovation ecosystem has been widely discussed, there are few studies examining the path of population richness of innovation ecosystem (PRIE) to innovation ecological effects (IEEF). This study aims to discuss the impact of PRIE on IEEF, the mediating effects of value co-creation mode (VCM) and value co-creation process (VCP), the moderating effects of innovation ecological environment (IEEN), innovation ecological mechanism (IEM), and innovation niche.
   Based on the survey data of electronic information companies in the Yangtze River Delta region, using multiple regressions and the Bootstrap method, the results of this study show as follows: Firstly, PRIE has a positive impact on IEEF. Diversified populations can bring diverse cooperative relationships, rich knowledge structures, and heterogeneous innovation resources, which can help enterprises effectively integrate knowledge and technologies in various fields, thereby stimulating potential business value and improving the innovation ecological effects of enterprises. Secondly, VCM and VCP play a mediating role in the relationship between PRIE and IEEF. On the one hand, diversified innovation entities can achieve virtual aggregation and innovation resources integration by means of the value co-creation mode, thus enhancing the IEEF. On the other hand, rich populations can learn interactively through value co-creation processes such as innovation forums and cooperation fairs to achieve complementary advantages, thereby promoting the generation of innovation ecological effects. Thirdly, IEEN plays a moderating role between PRIE and IEEF. Specifically, in a good innovation ecological environment, diverse populations can effectively achieve information dissemination and resource allocation, which is conducive to strengthening the positive impact of PRIE on IEEF. Fourthly, IEM has a moderated mediating effect on the relationship among "PRIE—VCM (VCP)—IEEF". Under the perfect innovation ecological mechanism, diversified populations can acquire better resources and complete high-quality and efficient interaction based on value co-creation mode, and establish common vision and rules based on value co-creation process, thus enhancing the impact on IEEF. Finally, innovation niche positively moderates the indirect effect of PRIE on IEEF via VCP. The result indicates that enterprises in the dominant ecological niche can combine different populations to participate in the value co-creation process such as new product development, strategic planning or process improvement by virtue of their extensive product system and resource orchestration capability, thus improving the IEEF. In addition, innovation niche positively moderates the indirect effect of PRIE on assimilation effect via VCM, but the indirect effect does not change significantly for growth effect and utilization effect. The possible explanation is that enterprises in different niches tend to adopt different strategies, therefore, the key for enterprises to obtain growth effect and utilization effect lies in the matching of their own ecological niche and ecological strategy.
    The following management implications are proposed based on the research findings: Firstly, enterprises should encourage heterogeneous members from different populations to co-create value. Specifically, enterprises should not only use different types of platforms to promote the integration of diversified online resources but also strengthen the interaction of innovation resources and the construction of strategic relationships with various groups. Secondly, government needs to create an innovative ecological environment based on the innovation concept of " cross-border integration", and play a guiding role in promoting the cooperation of diversified populations. On the one hand, the government should build an open and shared innovation platform; on the other hand, the government need mobilize the enthusiasm of enterprises and multi-entities to carry out technological innovation together through policy support. Thirdly, enterprises should select high-quality partners by establishing a selection mechanism in homogeneous populations; meanwhile, the relatively fair income distribution and risk bearing mechanism within the ecosystem should be constructed. Fourthly, enterprises can strengthen the strategic niche management and promote the expansion of innovation niche through expectation convergence, network management, and interactive learning, thus providing adaptive conditions for the formation of IEEF.

Key words:  population richness, value co-creation, innovation ecological mechanism, innovation niche