Zou Chris B, Caterina Giulia L, Will Rodney E, Stebler Elaine, Turton Donald
Department of Natural Resource Ecology & Management, Oklahoma State University, Stillwater, OK 74078, United States of America.
Universidade Estadual Paulista, Botucatu, SP, Brasil.
PLoS One. 2015 Nov 6;10(11):e0141422. doi: 10.1371/journal.pone.0141422. eCollection 2015.
Rainfall partitioning and redistribution by canopies are important ecohydrological processes underlying ecosystem dynamics. We quantified and contrasted spatial and temporal variations of rainfall redistribution for a juniper (Juniperus virginiana, redcedar) woodland and a tallgrass prairie in the south-central Great Plains, USA. Our results showed that redcedar trees had high canopy storage capacity (S) ranging from 2.14 mm for open stands to 3.44 mm for closed stands. The canopy funneling ratios (F) of redcedar trees varied substantially among stand type and tree size. The open stands and smaller trees usually had higher F values and were more efficient in partitioning rainfall into stemflow. Larger trees were more effective in partitioning rainfall into throughfall and no significant changes in the total interception ratios among canopy types and tree size were found. The S values were highly variable for tallgrass prairie, ranging from 0.27 mm at early growing season to 3.86 mm at senescence. As a result, the rainfall interception by tallgrass prairie was characterized by high temporal instability. On an annual basis, our results showed no significant difference in total rainfall loss to canopy interception between redcedar trees and tallgrass prairie. Increasing structural complexity associated with redcedar encroachment into tallgrass prairie changes the rainfall redistribution and partitioning pattern at both the temporal and spatial scales, but does not change the overall canopy interception ratios compared with unburned and ungrazed tallgrass prairie. Our findings support the idea of convergence in interception ratio for different canopy structures under the same precipitation regime. The temporal change in rainfall interception loss from redcedar encroachment is important to understand how juniper encroachment will interact with changing rainfall regime and potentially alter regional streamflow under climate change.
冠层对降雨的分配和再分配是生态系统动态变化背后重要的生态水文过程。我们对美国大平原中南部一片杜松（维吉尼亚杜松，红刺柏）林地和一片高草草原降雨再分配的时空变化进行了量化和对比。我们的结果表明，杜松的冠层截留能力（S）较高，从开阔林分的2.14毫米到郁闭林分的3.44毫米不等。杜松的冠层集流率（F）在林分类型和树木大小之间差异很大。开阔林分和较小的树木通常具有较高的F值，并且在将降雨分配为茎流方面更有效。较大的树木在将降雨分配为穿透雨方面更有效，并且未发现冠层类型和树木大小之间的总截留率有显著变化。高草草原的S值变化很大，从生长初期的0.27毫米到衰老期的3.86毫米不等。因此，高草草原的降雨截留具有很高的时间不稳定性。从年度来看，我们的结果表明，杜松和高草草原冠层截留造成的总降雨损失没有显著差异。与杜松侵入高草草原相关的结构复杂性增加，改变了降雨再分配和时空尺度上的分配模式，但与未燃烧和未放牧的高草草原相比，并没有改变整体冠层截留率。我们的研究结果支持了在相同降水条件下不同冠层结构截留率趋同的观点。杜松侵入导致的降雨截留损失的时间变化对于理解杜松侵入将如何与不断变化的降雨模式相互作用以及在气候变化下可能改变区域径流至关重要。
