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Mediating Water Temperature Increases Due to Livestock and Global Change in High Elevation Meadow Streams of the Golden Trout Wilderness.

Nusslé S, Matthews KR, Carlson SM - PLoS ONE (2015)

Bottom Line: Inside the livestock exclosure in Mulkey, we found that riverbank vegetation was both larger and denser than outside the exclosure where cattle were present, resulting in more shaded waters and cooler maximal temperatures inside the exclosure.In addition, between meadows comparisons showed that water temperatures were cooler in the ungrazed meadows compared to the grazed area in the partially grazed meadow.Our results highlight that land use can interact with climate change to worsen the local thermal conditions for taxa on the edge and that protecting riparian vegetation is likely to increase the resiliency of these ecosystems to climate change.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy & Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Rising temperatures due to climate change are pushing the thermal limits of many species, but how climate warming interacts with other anthropogenic disturbances such as land use remains poorly understood. To understand the interactive effects of climate warming and livestock grazing on water temperature in three high elevation meadow streams in the Golden Trout Wilderness, California, we measured riparian vegetation and monitored water temperature in three meadow streams between 2008 and 2013, including two "resting" meadows and one meadow that is partially grazed. All three meadows have been subject to grazing by cattle and sheep since the 1800s and their streams are home to the imperiled California golden trout (Oncorhynchus mykiss aguabonita). In 1991, a livestock exclosure was constructed in one of the meadows (Mulkey), leaving a portion of stream ungrazed to minimize the negative effects of cattle. In 2001, cattle were removed completely from two other meadows (Big Whitney and Ramshaw), which have been in a "resting" state since that time. Inside the livestock exclosure in Mulkey, we found that riverbank vegetation was both larger and denser than outside the exclosure where cattle were present, resulting in more shaded waters and cooler maximal temperatures inside the exclosure. In addition, between meadows comparisons showed that water temperatures were cooler in the ungrazed meadows compared to the grazed area in the partially grazed meadow. Finally, we found that predicted temperatures under different global warming scenarios were likely to be higher in presence of livestock grazing. Our results highlight that land use can interact with climate change to worsen the local thermal conditions for taxa on the edge and that protecting riparian vegetation is likely to increase the resiliency of these ecosystems to climate change.

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Maxima of the weekly maximal temperature (MWmaxT).The upper three panels (A-C) represent the distribution of the probes along the streambed in each meadow. All three rivers flow from North to South. The color code represents the maximum of the weekly maximal temperature (MWmaxT) in each probe: blue is used to represent probes where temperature never reaches 16°C, violet-blue when the highest temperatures were between 16–18°C, violet for 18–20°C, red-violet for 20–22°C, and red for temperatures higher than 22°C. The three larger panels (D-F) represent the same information with the maximum of the weekly maximal temperature (MWmaxT) on the y-axis and the distance from the first probe on the x-axis. The color code for the dots is the same as in the previous panels (A-C), and the red (blue) coloration between the dots represents whether the temperatures are above (below) the average weekly maximal temperature (WmaxT) observed across the three meadows. The regression lines represent the trends of maximal temperature (MWmaxT) over distance (solid lines are significant, while dashed lines are not). The grey area in Mulkey represents the cattle-exclosure, and the blue lines on the x-axis represent the different tributaries entering the system.
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pone.0142426.g004: Maxima of the weekly maximal temperature (MWmaxT).The upper three panels (A-C) represent the distribution of the probes along the streambed in each meadow. All three rivers flow from North to South. The color code represents the maximum of the weekly maximal temperature (MWmaxT) in each probe: blue is used to represent probes where temperature never reaches 16°C, violet-blue when the highest temperatures were between 16–18°C, violet for 18–20°C, red-violet for 20–22°C, and red for temperatures higher than 22°C. The three larger panels (D-F) represent the same information with the maximum of the weekly maximal temperature (MWmaxT) on the y-axis and the distance from the first probe on the x-axis. The color code for the dots is the same as in the previous panels (A-C), and the red (blue) coloration between the dots represents whether the temperatures are above (below) the average weekly maximal temperature (WmaxT) observed across the three meadows. The regression lines represent the trends of maximal temperature (MWmaxT) over distance (solid lines are significant, while dashed lines are not). The grey area in Mulkey represents the cattle-exclosure, and the blue lines on the x-axis represent the different tributaries entering the system.

Mentions: In Mulkey Meadows, we found increasing maximal temperatures (MWmaxT) from upstream to downstream outside the exclosure where cattle are present: 0.41 ± 0.14°C per 100 meters (Fig 4D; linear regression: t14 = 3.02, p < 0.01), and we did not find significant autocorrelation in the residuals (Moran’s I autocorrelation coefficient was equal to 0.041 ± 0.053, p = 0.44). The greater the distance water travelled in the stretch of stream open to cattle grazing, the warmer the stream temperatures. At the end of the cattle grazing section, in the upstream part of the exclosure, water temperatures reached 24°C each day during seven consecutive days across the study duration (MwmaxT). Interestingly, this temperature trend with distance downstream was reversed once the cattle were excluded from the river via the cattle exclusion fence: -0.25 ± 0.10°C per 100 meters (linear regression: t12 = -2.44, p < 0.05), again, no significant autocorrelation was found in the residuals (Moran’s I = 0.034 ± 0.052, p = 0.52). In contrast, no trends in distance were observed in maximal temperature (MWmaxT) in the two other meadows where cattle were absent since 2001 (Ramshaw, linear regression: t28 = -0.11, p = 0.92, Fig 4E, Big Whitney, linear regression: t19 = 0.062, p = 0.95, Fig 3F). We found no spatial autocorrelation in the residuals of the linear regressions in the other two meadow streams. Moran’s I autocorrelation coefficient was equal to 0.0006 ± 0.029 (p = 0.98) in Ramshaw Meadows, and 0.005 ± 0.037 (p = 0.90) in Big Whitney Meadow. In other words, there was a non-significant correlation between neighboring data after accounting for the distance between probes.


Mediating Water Temperature Increases Due to Livestock and Global Change in High Elevation Meadow Streams of the Golden Trout Wilderness.

Nusslé S, Matthews KR, Carlson SM - PLoS ONE (2015)

Maxima of the weekly maximal temperature (MWmaxT).The upper three panels (A-C) represent the distribution of the probes along the streambed in each meadow. All three rivers flow from North to South. The color code represents the maximum of the weekly maximal temperature (MWmaxT) in each probe: blue is used to represent probes where temperature never reaches 16°C, violet-blue when the highest temperatures were between 16–18°C, violet for 18–20°C, red-violet for 20–22°C, and red for temperatures higher than 22°C. The three larger panels (D-F) represent the same information with the maximum of the weekly maximal temperature (MWmaxT) on the y-axis and the distance from the first probe on the x-axis. The color code for the dots is the same as in the previous panels (A-C), and the red (blue) coloration between the dots represents whether the temperatures are above (below) the average weekly maximal temperature (WmaxT) observed across the three meadows. The regression lines represent the trends of maximal temperature (MWmaxT) over distance (solid lines are significant, while dashed lines are not). The grey area in Mulkey represents the cattle-exclosure, and the blue lines on the x-axis represent the different tributaries entering the system.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643935&req=5

pone.0142426.g004: Maxima of the weekly maximal temperature (MWmaxT).The upper three panels (A-C) represent the distribution of the probes along the streambed in each meadow. All three rivers flow from North to South. The color code represents the maximum of the weekly maximal temperature (MWmaxT) in each probe: blue is used to represent probes where temperature never reaches 16°C, violet-blue when the highest temperatures were between 16–18°C, violet for 18–20°C, red-violet for 20–22°C, and red for temperatures higher than 22°C. The three larger panels (D-F) represent the same information with the maximum of the weekly maximal temperature (MWmaxT) on the y-axis and the distance from the first probe on the x-axis. The color code for the dots is the same as in the previous panels (A-C), and the red (blue) coloration between the dots represents whether the temperatures are above (below) the average weekly maximal temperature (WmaxT) observed across the three meadows. The regression lines represent the trends of maximal temperature (MWmaxT) over distance (solid lines are significant, while dashed lines are not). The grey area in Mulkey represents the cattle-exclosure, and the blue lines on the x-axis represent the different tributaries entering the system.
Mentions: In Mulkey Meadows, we found increasing maximal temperatures (MWmaxT) from upstream to downstream outside the exclosure where cattle are present: 0.41 ± 0.14°C per 100 meters (Fig 4D; linear regression: t14 = 3.02, p < 0.01), and we did not find significant autocorrelation in the residuals (Moran’s I autocorrelation coefficient was equal to 0.041 ± 0.053, p = 0.44). The greater the distance water travelled in the stretch of stream open to cattle grazing, the warmer the stream temperatures. At the end of the cattle grazing section, in the upstream part of the exclosure, water temperatures reached 24°C each day during seven consecutive days across the study duration (MwmaxT). Interestingly, this temperature trend with distance downstream was reversed once the cattle were excluded from the river via the cattle exclusion fence: -0.25 ± 0.10°C per 100 meters (linear regression: t12 = -2.44, p < 0.05), again, no significant autocorrelation was found in the residuals (Moran’s I = 0.034 ± 0.052, p = 0.52). In contrast, no trends in distance were observed in maximal temperature (MWmaxT) in the two other meadows where cattle were absent since 2001 (Ramshaw, linear regression: t28 = -0.11, p = 0.92, Fig 4E, Big Whitney, linear regression: t19 = 0.062, p = 0.95, Fig 3F). We found no spatial autocorrelation in the residuals of the linear regressions in the other two meadow streams. Moran’s I autocorrelation coefficient was equal to 0.0006 ± 0.029 (p = 0.98) in Ramshaw Meadows, and 0.005 ± 0.037 (p = 0.90) in Big Whitney Meadow. In other words, there was a non-significant correlation between neighboring data after accounting for the distance between probes.

Bottom Line: Inside the livestock exclosure in Mulkey, we found that riverbank vegetation was both larger and denser than outside the exclosure where cattle were present, resulting in more shaded waters and cooler maximal temperatures inside the exclosure.In addition, between meadows comparisons showed that water temperatures were cooler in the ungrazed meadows compared to the grazed area in the partially grazed meadow.Our results highlight that land use can interact with climate change to worsen the local thermal conditions for taxa on the edge and that protecting riparian vegetation is likely to increase the resiliency of these ecosystems to climate change.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy & Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Rising temperatures due to climate change are pushing the thermal limits of many species, but how climate warming interacts with other anthropogenic disturbances such as land use remains poorly understood. To understand the interactive effects of climate warming and livestock grazing on water temperature in three high elevation meadow streams in the Golden Trout Wilderness, California, we measured riparian vegetation and monitored water temperature in three meadow streams between 2008 and 2013, including two "resting" meadows and one meadow that is partially grazed. All three meadows have been subject to grazing by cattle and sheep since the 1800s and their streams are home to the imperiled California golden trout (Oncorhynchus mykiss aguabonita). In 1991, a livestock exclosure was constructed in one of the meadows (Mulkey), leaving a portion of stream ungrazed to minimize the negative effects of cattle. In 2001, cattle were removed completely from two other meadows (Big Whitney and Ramshaw), which have been in a "resting" state since that time. Inside the livestock exclosure in Mulkey, we found that riverbank vegetation was both larger and denser than outside the exclosure where cattle were present, resulting in more shaded waters and cooler maximal temperatures inside the exclosure. In addition, between meadows comparisons showed that water temperatures were cooler in the ungrazed meadows compared to the grazed area in the partially grazed meadow. Finally, we found that predicted temperatures under different global warming scenarios were likely to be higher in presence of livestock grazing. Our results highlight that land use can interact with climate change to worsen the local thermal conditions for taxa on the edge and that protecting riparian vegetation is likely to increase the resiliency of these ecosystems to climate change.

Show MeSH
Related in: MedlinePlus