Tuesday, February 26, 2013

Spittle Bugs

We have been seeing spittle bubbling out of trees, especially in today's rain.  Might be a spittlebug.
"a fat little dark-eyed green creature about the size of a sesame seed called a froghopper nymph, so named for the adult insect's squat shape, pop eyes and leaping ability. The nymph stage is better known as a spittlebug. Froghoppers/spittlebugs insert their "beak" & suck sap through their bodies, extracting nutrients. As the liquid comes out the other end, mixed with soapy abdominal secretions, the insect puffs air into it through a special organ, blowing bubbles. The froth flows down and around the nymph (they feed facing head down), keeping it cool, moist and hidden from you (unless you look)."

Wednesday, February 06, 2013

Bankfull Flood on the Haw River, North Carolina

There is abundant evidence of a bankfull flood event on the Haw River, upstream of Bynum, North Carolina.

Let's see what the USGS Gauge at Bynum says.

 A gauge height over 11 feet counts as a flood...and it is more than 7 feet above current flow.  Note that this is a very wide river, so the actual volume was much more than 7 times...according to the USGS calculation, the flow was near 20,000 CFS, over 30 times the current flow of 600 CFS.

How does the compare to previous floods?
This January flood appears to be a bankfull event that was surpassed in 2008 (the first year of record for Bynum), 2009, and 2010, (but not in 2011 or 2012).  Many of these large floods happen in the early spring, perhaps when the heavy rains fall on an already-saturated watershed.

This is what happened the week of January 13th.  On top of the previous week's rain, there was significant rain on Monday the 14th and Wednesday the 16th.  The storm continued into Thursday, bringing more than an inch of thunderstorm rain (and snow) on top of the saturated landscape.  The Haw river flow peaked soon thereafter, in the early morning hours of January 18th.

Sunday, February 03, 2013

February Blocking Pattern

This computer model (GFS) of near-surface temperature (actually, just above the boundary layer) and atmospheric pressure shows an interesting pattern of high and low pressure areas.  A high pressure region over the Azores is predicted to hold steady for the next several weeks, in effect blocking the normal flow of the jet stream and Eastward-migrating low pressure regions.  These lows are forced to travel (clockwise) all the way around the high pressure region.  The consequence appears to be a trough in the jet stream over Eastern  North America, leading to large incursions of Arctic air, and very, very cold temperatures (see graph).

Friday, February 01, 2013

Do endemic taxa correlate?

One of the main assumptions of many biodiversity assessments and conservation efforts is that biodiversity correlates across taxa. In other words, an ecosystem with high plant diversity might be expected to also harbor high lichen diversity, high arthropod diversity, and a great many birds, bees, and bloomin' confusion. 

If this assumption is true, than scientists could study one taxa, say lichen, and use the results as a surrogate for studying all of the other possible taxa. But a new study by Dr. Che-Castaldo questions this "surrogacy" assumption:

"Testing Surrogacy Assumptions: Can Threatened and Endangered Plants Be 
Grouped by Biological Similarity and Abundances?"


"There is renewed interest in implementing surrogate species approaches in 
conservation planning due to the large number of species in need of 
management but limited resources and data. One type of surrogate approach 
involves selection of one or a few species to represent a larger group of 
species requiring similar management actions, so that protection and 
persistence of the selected species would result in conservation of the 
group of species. However, among the criticisms of surrogate approaches is 
the need to test underlying assumptions, which remain rarely examined. In 
this study, we tested one of the fundamental assumptions underlying use of 
surrogate species in recovery planning: that there exist groups of 
threatened and endangered species that are sufficiently similar to warrant 
similar management or recovery criteria. Using a comprehensive database of 
all plant species listed under the U.S. Endangered Species Act and 
tree-based random forest analysis, we found no evidence of species groups 
based on a set of distributional and biological traits or by abundances 
and patterns of decline. Our results suggested that application of 
surrogate approaches for endangered species recovery would be unjustified. 
Thus, conservation planning focused on individual species and their 
patterns of decline will likely be required to recover listed species."

Similar conclusions have been reached by a other studies.  For example, Erhlich et. al. 2002 found that in subalpine meadows in Colorado, indicator taxa show no skill in predicting diversity of other taxa, even among phylogenetically related species (in this case, butterflies and moths).