Upcoming events and meetings

As a reference, here are dates of interest:

October 29, 2008: Conference call at 9:30am (AZ time)
November 12, 2008: Conference call at 9:30am (Mountain Standard Time, includes AZ)
November 20-21, 2008: Moab meeting with Greg Okin
December 3, 2008: Meeting with 3 CO-PIs and Travis in Flagstaff

Piecewise regression for Semidesert Sandy Loam (Fourwing Saltbush)

I have been working with Mark's data as I try to build the STM and think about the first ecosite (Semidesert SaL). I ran a multiple regression investigating factors that influence soil aggregate stability. "Good" BSC points showed the strongest influence on soil stability. I then ran a piecewise regression, which yielded the following pattern (breakpoint of 22 ± 5). Red points are "grazed", open points are "ungrazed". A similar pattern is shown in the presentation Mark put together that was presented at the SLC workshop (slide 9 of SemidesertSandyLoam.ppt).

Updated List of Datasets

After meeting with Sue Phillips in Moab on Monday, October 20th, 2008, we have acquired new datasets. The list below includes the names given to the folders by Sue Phillips, but I am not yet sure the nature of the datasets (i.e., what was measured, where, when, etc.).

Here is a list of our datasets to date:

(1) data from Mark (CANY_Dugout_Combined_12Jun08_mem.xls)
(2) data from John Spence via Chris (Upland_Data.xls)
(3) data from John Spence via Mark (CARE_Exclosures.xls)
(4) data from Sue Phillips/Belnap lab:
a. ccows
b. Glen Canyon
c. I&M BSNE
d. Kleiner
e. rainfall sim
f. SERDP
g. SEUG
h. thumper
i. Needles (Virginia Park, Chesler Park)

State and Transition Monitoring Workshop Presentations

Some good presentations here for reference:
http://oregonstate.edu/dept/range/events/archivedevents/StateAndTransitionMonitoringPage.php

Datasets to date

As a reference for you to know which datasets I have, I will update this within 24 hours of receiving a new dataset.

As of 11:00AM on 10.06.08, I have:

(1) data from Mark (CANY_Dugout_Combined_12Jun08_mem.xls)
(2) data from Jayne/Sue via Steve (belnap_needles file folder)
(3) data from John Spence via Chris (Upland_Data.xls)
(4) data from John Spence via Mark (CARE_Exclosures.xls)

Travis

Piecewise Regression for Blackbrush (Desert Shallow Sandy Loam and Desert Sandy Loam)

I was "messing around" with piecewise regression and Mark's CANY/BLM data, exploring patterns between vegetation and soil stability for Blackbrush dominated ecological sites. It didn't take long to find an interesting pattern and after running a piecewise regression, I was able to calculate the breakpoint (threshold?) and confidence level around it (standard error). I plotted the data coding the observations by "grazed" or "ungrazed". These are very preliminary, but I thought this was interesting. Someone might argue that because soil stability is measured categorically you would expect this kind of "saturating" relationship. But, I thought I would go ahead and share in case anybody actually looks at this.

Updated framework

"All models are wrong, but some are useful." - G.E.P. Box

"Box and arrows won't get rid of cedar, but a box of matches will" - John Weir, 2006 (cited by Fuhlendorf)

I continue to update the framework using concepts derived from the existing framework, the SLC workshop, and the literature (using STM literature and threshold literature). My hope is to produce an updated framework that coincides nearly perfectly - in terms of concepts - with an updated table.

Here is the current draft framework (9.22.08). Click on the images to enlarge.

And the corresponding draft Threshold Attribute Table.