Drought

Lake Shasta Feb-Oct 2014 comparison.
Lake Shasta Feb-Oct 2014 comparison.

Drought - ARMI Papers & Reports


Papers & Reports Survival estimates for the invasive American Bullfrog
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Authors: Howell PE, Muths E, Sigafus BH, Hossack BR | Outlet: Amphibia-Reptilia
We used five years of capture mark-recapture data to estimate annual apparent survival of post-metamorphic bullfrogs in a population on the Buenos Aires National Wildlife Refuge in their invaded range in Arizona, U.S.A.
Study area in southern Arizona (USA) showing water endmember location (Parker Canyon Lake; bottom right) and examples of three waterbodies with different sizes and spectral characteristics using June 2007 Landsat 5 TM (left) and September 2018 Landsat 8 OLI (right).
Study area in southern Arizona (USA) showing water endmember location (Parker Canyon Lake; bottom right) and examples of three waterbodies with different sizes and spectral characteristics using June 2007 Landsat 5 TM (left) and September 2018 Landsat 8 OLI (right).
Papers & Reports Estimating inundation of small waterbodies with sub-pixel analysis of Landsat imagery: long-term trends in surface water area and evaluation of common drought indices
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Authors: Sall I, Jarchow CJ, Sigafus BH, Eby LA, Forzley MJ, Hossack BH | Outlet: Remote Sensing in Ecology and Conservation
Small waterbodies are numerically dominant in many landscapes and provide several important ecosystem services, but automated measurement of waterbodies smaller than a standard Landsat pixel (0.09 ha) remains challenging. To further evaluate sub-Landsat pixel techniques for estimating inundation extent of small waterbodies (basin area: 0.061.79 ha), we used a partial spectral unmixing method with matched filtering applied to September 1985–2018 Landsat 5 and 8 imagery from southern Arizona, USA. We estimated trends in modeled surface water area each September and evaluated the ability of several common drought indices to explain variation in mean water area. Our methods accurately classified waterbodies as dry or inundated (Landsat 5: 91.3%; Landsat 8: 98.9%) and modeled and digitized surface water areas were strongly correlated (R2 = 0.700.92; bias = -0.024 – -0.015 ha). Estimated surface water area was best explained by the 3-month seasonal standardized precipitation index (SPI03; July?September) and. We found a wide range of estimated relationships between drought indices (e.g., SPI vs. Palmer Drought Severity Index) and estimated water area, even for different durations of the same drought index (e. g., SPI01 vs SPI12). Mean surface area of waterbodies decreased by ~14% from September 1985 to September 2018, which matched declines in annual precipitation in the area and is consistent with broader trends of reduced inundation extent based on larger waterbodies. Estimated of surface water area and trends over time were also consistent when we limited analyses to waterbodies ? 0.04 ha or those that varied most in size (based on CV). These results emphasize the importance of understanding local systems when relying on drought indices to infer variation in past or future surface water dynamics. Several challenges remain before widespread application of sub-pixel methods is feasible, but our results provide further evidence that partial spectral unmixing with matched filtering provides reliable measures of inundation extent of small waterbodies.
Juvenile California newt ([I]Taricha torosa[/I]) from southern California.  The larval stage is very sensitive to rainfall and water availability.
Juvenile California newt (Taricha torosa) from southern California. The larval stage is very sensitive to rainfall and water availability.
USGS
Papers & Reports Amphibian responses in the aftermath of extreme climate events
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Authors: Bucciarelli G M, Clark M, Delaney K S, Riley S P D, Shaffer H B, Fisher R N, Honeycutt R L, Kats L B | Date: 2020-02-25 | Outlet: Scientific Reports 10:3409 | Format: .PDF
Climate change-induced extinctions are estimated to eliminate one in six known species by the end
of the century. One major factor that will contribute to these extinctions is extreme climatic events.
Here, we show the ecological impacts of recent record warm air temperatures and simultaneous peak
drought conditions in California. From 2008–2016, the southern populations of a wide-ranging endemic
amphibian (the California newt, Taricha torosa) showed a 20% reduction to mean body condition and
significant losses to variation in body condition linked with extreme climate deviations. However,
body condition in northern populations remained relatively unaffected during this period. Range-wide
population estimates of change to body condition under future climate change scenarios within the
next 50 years suggest that northern populations will mirror the loss of body condition recently observed
in southern populations. This change is predicated on latter 21st century climate deviations that
resemble recent conditions in Southern California. Thus, the ecological consequences of climate change
have already occurred across the warmer, drier regions of Southern California, and our results suggest
that predicted climate vulnerable regions in the more mesic northern range likely will not provide
climate refuge for numerous amphibian communities.
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