Manipulative experiments and space-for-time substitutions are two main approaches used to infer the impacts of future climate change on ecological processes, such as litter decomposition. The potential limitations of these approaches are well-recognized. Here, we address the congruence between these two approaches by comparing decomposition rates of leaf litter from four wetland plant species in response to (i) in-situ experimental warming (manipulative warming), and (ii) broad-scale spatial gradients (natural warming) over one-year observation of 2019. Manipulative warming was achieved by using open-top chambers (OTCs), and natural warming was followed along an altitudinal gradient from a high altitude site to a low site. Litter decomposition rates increased with temperature increasing in both OTC- and gradient-based approaches. However, litter decomposed faster along with the decreasing altitude than predicted by the manipulated rise in temperature, especially for those plants being resistant to decompose. For the gradient-based approach, the interaction effects between temperature and precipitation explained up to 44.1% of litter decomposition dynamics and served as a key to differentiate these two approaches. These results support the view that space-for-time substitution over broad-scale spatial gradients may magnify the responses of certain ecological processes to further climate warming. Our work is the first study to compare the characteristics of decomposition of wetland plant litter types in OTC- and natural gradient-based warming experiments.

操纵性实验和时空替代是用于推断未来气候变化对生态过程（如凋落物分解）的影响的两种主要方法。这些方法的潜在局限性已广为人知。在这里，我们通过比较四种湿地植物叶片凋落物的分解率（i）原位实验变暖（操纵变暖）和（ii）来解决这两种方法之间的一致性。）于2019年进行的一年观测中的大规模空间梯度变化（自然变暖）。通过使用开放式顶棚（OTC）进行操纵性变暖，然后沿着从高海拔站点到低海拔站点的高度梯度进行自然变暖。 。在基于OTC和基于梯度的方法中，凋落物分解速率均随温度的升高而增加。但是，凋落物随高度降低而分解的速度比受控的温度升高所预测的要快，尤其是对于那些耐分解的植物而言。对于基于梯度的方法，温度与降水之间的相互作用影响解释了高达44.1％的凋落物分解动力学，并成为区分这两种方法的关键。这些结果支持这样的观点，即在大规模空间梯度上进行时空替代可能会放大某些生态过程对进一步气候变暖的响应。我们的工作是在基于OTC和基于自然梯度的变暖实验中比较湿地植物凋落物类型分解特征的第一项研究。