The delivery of wood to streams varies in space and time and may occur continuously or episodically. Once in a stream, wood may be retained or transported due to the balance between driving (water flow) and resisting forces (channel features and wood characteristics). Despite there being few studies directly measuring wood mobility, notable variations in annual transport rates and mean travelled distances have already been detected worldwide. In the tropics, due to wetter and warmer conditions and consequently higher decay rates and peak discharge, wood is believed that more readily degraded and transported downstream. However, there exists a knowledge gap regarding wood dynamics in tropical streams and even more considering tropical non-forested environments. In the present study, we aimed to document large wood (LW) recruitment, retention, and mobilization over a period of one year in eight low-order streams of the Cerrado (the South American Savanna) by tagging and tracing LW pieces. We detected high LW transport and recruitment rates in Cerrado streams, such that the total wood amounts remained constant over time. However, there were important differences between streams due to their distinct channel morphologies and the occurrence of episodic events. The LW length and diameter, original location and orientation were the most important factors in the prediction of the LW travelled distance, which ranged from zero to almost 100 m in one year. Our findings provide unprecedented information regarding wood mobility in tropical savanna streams in South America. To further advance knowledge about the dynamics of wood in Cerrado streams, future studies should characterize the great diversity of wood, especially with regard to densities that may strongly affect wood mobility. Furthermore, it is essential to perform long-term studies to document the dynamics of wood over years in these environments.

中文翻译：

---

巴西稀树草原低级溪流中大量木材的补充、保留和动员

木材向溪流的输送在空间和时间上各不相同，并且可能连续或间歇地发生。一旦进入溪流，由于驱动力（水流）和阻力（河道特征和木材特性）之间的平衡，木材可能被保留或运输。尽管直接测量木材流动性的研究很少，但全球范围内已发现年运输率和平均行驶距离的显着变化。在热带地区，由于气候更加潮湿和温暖，因此腐烂率和峰值排放量较高，木材被认为更容易降解并迁移到下游。然而，关于热带溪流中的木材动态，甚至更多地考虑到热带非森林环境，存在知识差距。在本研究中，我们的目的是通过标记和追踪大型木材 (LW) 碎片，记录塞拉多（南美稀树草原）八个低阶溪流一年内的大型木材 (LW) 招募、保留和动员情况。我们在塞拉多溪流中检测到较高的 LW 运输和补充率，因此木材总量随着时间的推移保持恒定。然而，由于不同的河道形态和偶发事件的发生，河流之间存在重要差异。LW 长度和直径、原始位置和方向是预测 LW 行驶距离的最重要因素，一年内行驶距离从零到近 100 m。我们的研究结果提供了有关南美洲热带稀树草原溪流木材流动性的前所未有的信息。为了进一步加深对塞拉多溪流中木材动态的了解，未来的研究应该描述木材的巨大多样性，特别是可能强烈影响木材流动性的密度。此外，有必要进行长期研究来记录木材在这些环境中多年来的动态。