Reid Joseph Pignatello, Schnitzer Stefan A, Powers Jennifer S
Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, United States of America.
Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201-1881, United States of America.
PLoS One. 2015 Nov 6;10(11):e0141891. doi: 10.1371/journal.pone.0141891. eCollection 2015.
Lianas (woody vines) are particularly abundant in tropical forests, and their abundance is increasing in the neotropics. Lianas can compete intensely with trees for above- and belowground resources, including water. As tropical forests experience longer and more intense dry seasons, competition for water is likely to intensify. However, we lack an understanding of how liana abundance affects soil moisture and hence competition with trees for water in tropical forests. To address this critical knowledge gap, we conducted a large-scale liana removal experiment in a seasonal tropical moist forest in central Panama. We monitored shallow and deep soil moisture over the course of three years to assess the effects of lianas in eight 0.64 ha removal plots and eight control plots. Liana removal caused short-term effects in surface soils. Surface soils (10 cm depth) in removal plots dried more slowly during dry periods and accumulated water more slowly after rainfall events. These effects disappeared within four months of the removal treatment. In deeper soils (40 cm depth), liana removal resulted in a multi-year trend towards 5-25% higher soil moisture during the dry seasons with the largest significant effects occurring in the dry season of the third year following treatment. Liana removal did not affect surface soil temperature. Multiple and mutually occurring mechanisms may be responsible for the effects of liana removal on soil moisture, including competition with trees, and altered microclimate, and soil structure. These results indicate that lianas influence hydrologic processes, which may affect tree community dynamics and forest carbon cycling.
藤本植物（木质藤本）在热带森林中尤为丰富，且在新热带地区其数量正在增加。藤本植物会与树木激烈竞争地上和地下资源，包括水分。随着热带森林经历更长且更强烈的旱季，对水分的竞争可能会加剧。然而，我们并不清楚藤本植物数量的增加如何影响土壤湿度，进而影响其与树木在热带森林中对水分的竞争。为填补这一关键的知识空白，我们在巴拿马中部的季节性热带湿润森林中开展了一项大规模的藤本植物清除实验。我们在三年时间里监测了浅层和深层土壤湿度，以评估藤本植物清除对八个0.64公顷清除区和八个对照区的影响。藤本植物清除对表层土壤产生了短期影响。清除区的表层土壤（深度10厘米）在干旱期干燥得更慢，降雨后积水也更慢。这些影响在清除处理后的四个月内消失。在更深层的土壤（深度40厘米）中，藤本植物清除导致旱季土壤湿度出现多年上升趋势，上升幅度为5% - 25%，最大的显著影响出现在处理后的第三年旱季。藤本植物清除并未影响表层土壤温度。藤本植物清除对土壤湿度产生影响可能是多种相互作用机制共同作用的结果，包括与树木的竞争、微气候改变以及土壤结构变化。这些结果表明，藤本植物会影响水文过程，这可能会影响树木群落动态和森林碳循环。
