Watershed degradation due to invasion threatens downstream water flows and associated ecosystem services. While this topic has been studied across landscapes that have undergone invasive-driven state changes (e.g., native forest to invaded grassland), it is less well understood in ecosystems experiencing within-system invasion (e.g. native forest to invaded forest). To address this subject, we conducted an integrated ecological and ecohydrological study in tropical forests impacted by invasive plants and animals. We measured soil infiltration capacity in multiple fenced (i.e., ungulate-free)/unfenced and native/invaded forest site pairs along moisture and substrate age gradients across Hawaii to explore the effects of invasion on hydrological processes within tropical forests. We also characterized forest composition, structure and soil characteristics at these sites to assess the direct and vegetation-mediated impacts of invasive species on infiltration capacity. Our models show that invasive ungulates negatively affect soil infiltration capacity consistently across the wide moisture and substrate age gradients considered. Additionally, several soil characteristics known to be affected by invasive ungulates were associated with local infiltration rates, indicating that the long-term secondary effects of high ungulate densities in tropical forests may be stronger than effects observed in this study. The effect of invasive plants on infiltration was complex and likely to depend on their physiognomy within existing forest community structure. These results provide clear evidence for managers that invasive ungulate control efforts can improve ecohydrological function of mesic and wet forest systems critical to protecting downstream and nearshore resources and maintaining groundwater recharge.

入侵造成的流域退化威胁下游水流和相关的生态系统服务。尽管已经研究了经过入侵驱动状态变化（例如，从原始森林到被入侵的草地）的景观，但是在经历系统内入侵的生态系统（例如，从原始森林到被入侵的森林）中，对这一主题的了解还很少。为了解决这个问题，我们在受入侵植物和动物影响的热带森林中进行了综合的生态和生态水文学研究。我们沿着整个夏威夷的水分和基质年龄梯度，测量了多个围栏（即无蹄类动物）/无围栏和原生/入侵森林站点对的土壤入渗能力，以探索入侵对热带森林内水文过程的影响。我们还描述了森林组成，这些地点的土壤结构和土壤特性，以评估入侵物种对渗透能力的直接影响和植被介导的影响。我们的模型表明，在考虑的较宽的湿度和基质年龄梯度下，侵袭性有蹄类动物对土壤的渗透能力产生了持续的负面影响。此外，一些已知受侵袭有蹄类动物影响的土壤特征与局部入渗率有关，这表明高有蹄类动物密度在热带森林中的长期次级影响可能要强于本研究中观察到的影响。入侵植物对渗透的影响是复杂的，可能取决于它们在现有森林群落结构中的相貌。