The expansion of woody riparian vegetation, and subsequent stream restoration, influences the metabolism of prairie streams
The expansion of woody riparian vegetation, and subsequent stream restoration, influences the metabolism of prairie streams
复制标题
木本河岸植被的扩张以及随后的溪流恢复影响了草原溪流的新陈代谢
DOI：
10.1111/j.1365-2427.2012.02778.x
复制
发表时间：
2012
影响因子：
2.7
通讯作者：
W. Dodds
中科院分区：
文献类型：
--
作者：
Alyssa J. Riley;W. Dodds
Tallgras草原及其溪流是高度濒危的生态系统，许多剩余的溪流受到木本河岸植被的侵蚀。河岸植被的增加将自然开放树冠的草原溪流转变为封闭的树冠系统。树冠覆盖度变化对河流新陈代谢的影响尚不清楚。2.我们的目标是确定在美国KS的Kings Creek的4年时间里，树冠覆盖对草原溪流新陈代谢的影响。比较了森林覆盖地区与自然开放树冠地区和恢复地区的代谢率，后者在2006年和2007年关闭了树冠，在2008年和2009年进行了开放树冠。全流代谢采用双站日变化估计法。在河岸去除后，测量了丝状藻类的叶绿素a浓度和质量，以评估开放和封闭树冠河段之间藻类生物量的潜在差异。3.代谢率在空间和时间上是可变的，即使这些地点位于非常相似的溪流上或在溪流中彼此相邻。河岸带植被去除前，植被盖度越大，全流群落呼吸(CR)和生态系统净生产量越大。在植被去除河段，去除后的总初级生产力略高。4.开阔地(自然开阔地和移除区)的叶绿素a浓度略高于封闭林冠，且季节间差异显著。开阔河段丝状藻类生物量大于封闭式河段。5.总体而言，恢复工作使开阔林冠的草原溪流得以恢复。木本扩张明显增加了CR，并将草原溪流代谢推向更净的异养状态。树冠覆盖度的增加减少了底栖叶绿素，降低了丝状藻类的优势，并可能改变溪流食物网的可用资源。这项研究的结果为土地管理者和自然资源保护者提供了洞察力，他们有兴趣保护草原溪流在他们自己的开阔树冠状态下。
SUMMARY 1. Tallgrass prairies and their streams are highly endangered ecosystems, and many remaining streams are threatened by the encroachment of woody riparian vegetation. An increase in riparian vegetation converts the naturally open-canopy prairie streams to closed-canopy systems. The effects of a change in canopy cover on stream metabolism are unknown. 2. Our goal was to determine the effects of canopy cover on prairie stream metabolism during a 4-year period in Kings Creek, KS, U.S.A. Metabolic rates from forested reaches were compared to rates in naturally open-canopy reaches and restoration reaches, the latter having closed canopies in 2006 and 2007 and open canopies in 2008 and 2009. Whole-stream metabolism was estimated using the two-station diurnal method. Chlorophyll a concentrations and mass of filamentous algae were measured after riparian removal to assess potential differences in algal biomass between reaches with open or closed canopies. 3. Metabolic rates were spatially and temporally variable even though the sites were on very similar streams or adjacent to each other within streams. Before riparian vegetation removal, whole-stream community respiration (CR) and net ecosystem production were greater with greater canopy cover. In the vegetation removal reaches, gross primary production was slightly greater after removal. 4. Chlorophyll a concentrations were marginally significantly greater in open (naturally open and removal reaches) than in closed canopy and differed significantly between seasons. Filamentous algal biomass was greater in open than in closed-canopy reaches. 5. Overall, the restoration allowed recovery of some features of open-canopy prairie streams. Woody expansion apparently increases CR and moves prairie stream metabolism towards a more net heterotrophic state. An increase in canopy cover decreases benthic chlorophyll, decreases dominance of filamentous algae and potentially alters resources available to the stream food web. The results of this study provide insights for land managers and conservationists interested in preserving prairie streams in their native open-canopy state.