What Causes/Prevents PMV Growth at Glamis?
Chart by Vincent J Brunasso, ASA Co Founder
The American Sand Association suggests taking the scientific approach to the Draft Recreation Management Plan (DRAMP) this month as the BLM tries to close even more recreation areas without taking scientific facts into account. I know, I know; it's nothing new, right?
The ASA says that ALL pertinent information that has been published on the PMV must be included to allow the public to make an informed decision on the validly of the claims and on Bureau of Land Management's (BLM) proposed restrictions on recreation.
The BLM is not demonstrating any facts based on rainfall or recreationists effect on the PMV as they prepare to close even more areas of the Imperial Sand Dune Recreation Area. The public needs to be made aware of all the facts, instead of having the BLM just try to ram it through.
You can read the entire final comment by the ASA on the matter here: Final_ASA_DRAMP_Comments_(7-17-2010).pdf (application/pdf Object).
The statement below is from Vincent J Brunasso on how and why he created this chart.
We always have known that rain is what makes the PMV grow or not grow, but no correlation has ever been done. To that end, here it is.
The rainfall data was taken from the Cauhilla ranger station and the Buttercup automated weather station (AWS) web pages. Each plot is the rainfall for the month as indicated added to the previous month - so it accumulates. The chart shows only rainfall from September through April as rains in other months probably don't do much good for the PMV and would clutter the graph. PMV numbers were taken from the BLM survey reports and are divided by 250,000 to keep the graph scale within reasonable limits.
The chart covers the following growing seasons:
2003 Survey for the 02-03 Growing Season: Not much rain so low PMV numbers
2004 Survey for the 03-04 Growing Season: What little rain there was came too late
2005 Survey for the 04-05 Growing Season: Rains started in August and were consistent through the season resulting in explosive germination and seed production. As perfect a rain curve as we're likely to see.
2006 Survey for the 05-06 Growing Season: A big storm in August, then little after that resulting in the worst year
2007 Survey for the 06-07 Growing Season: Fair amount of rain at beginning of season, not much after that - fewer numbers than if rain had continued.
Even though not scientific (but the data used is), the rain data we have is from only two stations, and rains can occur in one area and not another, it still paints a vivid picture - bottom line: the amount and timing of rain makes the plants grow (or not).
I hope you see fit to use this in your comments on the DRAMP.