Length of vegetation's water memory and its implication for resilience

Memory effects emphasizes that antecedent climate conditions impact current vegetation productivity. This temporal linkages was found strong in water-limited regions and its strength exhibited a weakening trend with increasing mean annual precipitation recently. However, the relative significance of antecedent precipitation in determining memory effects was not known. Here we quantified the length of water memory and showed that water availability within memory may play dominant role in determining memory effects. More importantly, the strength of memory effects was also considered a useful metric to measure the responding rate of ecosystems to external perturbations, an important component of vegetation resilience. Consistent with current theory, our results showed that vegetation with longer water memory may be accompanied with longer stochastic perturbations, thereby recovered slower to equilibrium state. Our results can help understand vegetation's responses to alterations in water availability and recognize ecosystems approach tipping points and vulnerable regions.