Codes and data of Long transients may be temporary visits of hidden alternative stable states

Ecosystems can fluctuate around a stable equilibrium or be in a transient state (the period toward a stable state). In practical applications, transient states may be mistakenly regarded as stable states, or vice versa, especially when multiple positive feedbacks are involved, which produce much more complex system equilibrium behavior than a single positive feedback. However, our current understanding remains limited. Using a long-term restoration project in the Tengger Desert as the study object, this study employed a minimal model to explain a long “transient state” of a dryland ecosystem after restoration under the effects of two positive feedbacks (water-vegetation and erosion-vegetation). The results indicated that the transient state, a shrub-dominated state, might be an alternative stable state maintained by water-vegetation positive feedback. Shifts in dominance between the two positive feedbacks caused the ecosystem to shift from a shrub-dominated state to a herbaceous-dominated state. The shrub-dominated state was masked due to the mechanisms of dominance shifting by the two positive feedbacks, a phenomenon we refer to as a “hidden alternative stable state”. This work proposes a novel perspective to study system dynamics – a switch of multiple positive feedbacks, and discovers a new explanation to transient state – temporary visits of hidden alternative stable states, which could significantly benefit practical ecosystem interventions.生态系统可围绕稳定平衡点波动，亦可处于瞬态（即趋近稳定状态的过渡阶段）。在实际应用中，瞬态常被误判为稳定状态，反之亦然；尤其当存在多重正反馈时，系统的平衡行为会比单一正反馈情形下更为复杂，这类误判更易发生。然而，当前学界对这类现象的认知仍较为有限。本研究以腾格里沙漠长期生态修复工程为研究对象，通过极简模型阐释了干旱区生态系统在修复后，受水-植被与侵蚀-植被两类正反馈作用影响下的长期"瞬态"现象。研究结果表明，该以灌木为主导的瞬态，或许是由水-植被正反馈维持的一种备选稳定状态。两类正反馈间的主导地位切换，可使生态系统从灌木主导态转变为草本主导态。受两类正反馈的主导地位切换机制影响，灌木主导态被隐藏，我们将该现象定义为"隐藏式备选稳定状态"。本研究提出了一种研究系统动力学的全新视角——多重正反馈的切换机制，并为瞬态现象提供了新的解释：即瞬态是隐藏式备选稳定状态的临时到访，该发现可对实际生态系统修复干预工作提供重要借鉴。