Batchelor Jonathan L, Ripple William J, Wilson Todd M, Painter Luke E
Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR, 97331, USA.
Environ Manage. 2015 Apr;55(4):930-42. doi: 10.1007/s00267-014-0436-2. Epub 2015 Feb 19.
We assessed the effects of the elimination of livestock in riparian systems at Hart Mountain National Antelope Refuge in southeastern Oregon, 23 years after the removal of cattle grazing, using 64 photos taken before grazing was removed compared with later retake photos. Two methods were used for this assessment: (1) a qualitative visual method comparing seven cover types and processes and (2) a new quantitative method of inserting digital line transects into photos. Results indicated that channel widths and eroding banks decreased in 64 and 73% of sites, respectively. We found a 90% decrease in the amount of bare soil (P < 0.001) and a 63% decrease in exposed channel (P < 0.001) as well as a significant increase in the cover of grasses/sedges/forbs (15% increase, P = 0.037), rushes (389% increase, P = 0.014), and willow (388% increase, P < 0.001). We also assessed the accuracy of the new method of inserting digital line transects into photo pairs. An overall accuracy of 91% (kappa 83%) suggests that digital line transects can be a useful tool for quantifying vegetation cover from photos. Our results indicate that the removal of cattle can result in dramatic changes in riparian vegetation, even in semi-arid landscapes and without replanting or other active restoration efforts.
在俄勒冈州东南部的哈特山国家羚羊保护区，我们评估了河岸系统中牲畜消除的影响，这是在取消牛群放牧23年后进行的，使用了64张在取消放牧之前拍摄的照片，并与之后重新拍摄的照片进行比较。本次评估采用了两种方法：（1）一种定性视觉方法，比较七种覆盖类型和过程；（2）一种新的定量方法，将数字线样带插入照片中。结果表明，分别有64%和73%的地点河道宽度和侵蚀河岸减少。我们发现裸土量减少了90%（P < 0.001），裸露河道减少了63%（P < 0.001），同时草/莎草/草本植物的覆盖度显著增加（增加了15%，P = 0.037），灯心草（增加了389%，P = 0.014）和柳树（增加了388%，P < 0.001）。我们还评估了将数字线样带插入照片对的新方法的准确性。总体准确率为91%（卡帕系数为83%），这表明数字线样带可以成为从照片中量化植被覆盖度有用工具。我们的结果表明，即使在半干旱景观中，且没有重新种植或其他积极的恢复措施，去除牛群也会导致河岸植被发生巨大变化。
