传粉昆虫下降背景下的授粉生态弹性: 内涵、机制和展望

全球传粉昆虫多样性正在下降, 如何保障农林生态系统传粉功能是当前研究的热点。理论上说, 传粉功能不仅与生态系统的传粉昆虫多样性相关, 还与生态系统的调节能力有关。近年来, 学者们逐渐认识到授粉生态弹性对传粉功能的影响。本文在回顾已有研究的基础之上, 总结传粉昆虫授粉生态弹性的内涵, 厘清授粉生态弹性与工程弹性、稳定性和抗性的异同。目前, 学者对授粉生态弹性形成机制开展广泛探讨, 提出功能冗余假说、密度补偿假说、响应多样性假说、连接周转假说和跨尺度弹性假说, 但这5个假说间的关系仍不清楚, 存在一词多义、词意混淆等现象。我们依次阐述功能冗余假说、密度补偿假说、响应多样性假说、连接周转假说和跨尺度弹性假说, 介绍不同假说中授粉生态弹性形成过程、研究热点和发展动态。通过解析授粉生态弹性的形成机制可知, 5个假说在内涵上存在紧密联系, 它们从不同空间尺度和研究对象下解释传粉昆虫授粉生态弹性的形成机制。未来授粉生态弹性研究将整合传粉昆虫群落动态和传粉功能动态的量化方法, 通过实验验证5个假说的合理性, 并揭示不同假说间的联系, 由此阐明授粉生态弹性的发生条件、形成阈值和动态规律。随着研究的深入, 授粉生态弹性理论有望用于指导农林生态系统传粉功能的经营管理。

Ecological resilience of pollination in the face of pollinator decline: Content,mechanism and perspective

Background & Aims: Pollinators are declining worldwide and there is a global concern about how to conserve pollination services of agroforestry ecosystems. In theory, the pollination services are determined not only by the level of pollinator diversity but also by the adaptive capability of pollinator communities against disturbances. Recently, researchers have realized the importance of ecological resilience of pollination; nevertheless, the concept of ecological resilience of pollination is not clear and it is often misapplied to other ecological processes, like engineering resilience, resistance, and stability. Objectives: This study explains the concept and content of ecological resilience of pollination and discusses the differences from other similar ecological processes. Moreover, the underlying mechanisms driving the ecological resilience of pollination are reviewed and the hypotheses explaining ecological resilience of pollination are summarized. The ecological importance of ecological resilience of pollination is addressed in terms of managing pollination functioning of agricultural ecosystems. Progresses: Ecosystems under outer disturbances can absorb the disturbances by reorganizing the inner structures or components to let the ecosystem functioning remain unchanged or at an acceptable level. Reorganization of the pollinator communities under disturbances drives the occurrence of ecological resilience of pollination. Functional redundancy, density compensation, response diversity, interaction turnover, and cross-scale resilience are the five hypotheses explaining the ecological resilience of pollination, but they are often used imprecisely and incorrectly. We state that the five hypotheses are different but internally interlinked, explaining the ecological resilience of pollination at different spatial scales. From functional redundancy, density compensation, response diversity, interaction turnover to cross-scale resilience, the five hypotheses explain the ecological resilience of pollination ranging from small to large scales and from simple to complex ecosystems. Moreover, the hypothesis running at a relatively large spatial scale (e.g. cross-scale resilience) can be applied to explain the hypothesis at a relatively small scale (e.g. functional redundancy and density compensation). For each hypothesis, a conceptual diagram is presented to illustrate how pollinators reorganize their communities to enhance the ecological resilience of pollination. The experimental evidences to support the five hypotheses are still in shortage, particularly for interaction turnover hypothesis and the cross-scale resilience hypothesis. Nowadays, few studies have explored the pollination functioning of ecosystems by methods integrating the five hypotheses. Moreover, the relationships among the five hypotheses are not tested empirically by field study, either. Therefore, more field evidences are expected to support those hypotheses. Perspectives: The ecological resilience of pollination is always measured using biodiversity indexes, such as species richness and Simpson diversity. Since ecological resilience of pollination is a measurement of ecosystem functioning, we suggest that its indictor need to integrate pollination functioning, such as pollen grains deposited on stigma surfaces, initial fruit sets and finial fruit sets. Future research also should examine how the disturbance intensification influences the ecological resilience of pollination and when the ecological resilience of pollination occurs. Moreover, the five hypotheses should be tested empirically and their relationships need to be explored. With the development of knowledge on ecological resilience of pollination, researchers can apply those theories to manage the agricultural ecosystems. For example, the ecological resilience of pollination can guide the researchers to determine when and how to provide the managed pollinators (e.g. honey bees) to safeguard the pollination functioning of ecosystems.