analogs to desert sand (Sand sagebrush)

My correspondance wiht NRCS about some analogs to the Desert Sand ecosite.

My question: I'm currently working on a project with Mark Miller trying to develop some state-and-transition models for the National Park Service. One ecosite I am trying to work on is Desert Sand 035XY115UT. I am curious, in your professional opinion, in this ecosite more or less the same as Sandy Upland 6-10 RO35XB217AZ in Arizona. They are both dominated by eolian processes, are mostly composed of deep Sheppard soils (Navajo-derived) over sandstone bedrock, and have an identical vegetation of ricegrass, dropseed, and sand sage. I ask because we are trying to collect relevant datasets to help inform our work, and I am aware of one with some data on Sandy uplands, so I was wondering if it was much of a stretch to say it is a very reasonable analog for the Utah office's Desert Sand. In my opinion the only difference is that one is in Arizona and one in Utah.

Shane Green:The sites you mention may be combined some day. It is possible that they will remain separate, depending on where they occur. The attached recent trip report (draft) from a couple of weeks ago describes the new LRUs that are being proposed in D35 for Utah. It may play out that the Utah site would be in the new 35.12 which is a little warmer, and consequently has blackbrush (in the area if not on this particular site) and the Arizona site may remain separate because is slightly cooler and occurs where there is no blackbrush. We need to see an extent map of the Arizona site to help make this decision.

Some of my records show that we have a draft S&TM for Desert Sand 035XY115UT, but I cannot find it. I still have a couple of places to look. I will get back with you on this.

If you and Mark are writing S&TMs for the NPS, please coordinate with us on all of them. NRCS has a contract with the NPS to update the soil surveys and develop S&TMs on all the sites in the parks eventually, and this work is ongoing, with some completed, some as drafts and some being reviewed, and all welcoming additional data, input and changes. It sounds to me like we should be working together on this.

My response:1) Yes I would like to coordinate my efforts with yours. Our initial goals with the S&T models are to develop models that not only include all of the relevant vegetation states, but incorporate crusts where needed (most of the sandy ecosystems and some others), and to try and include plausible global change impacts. The second, and real goal, is to try and put a number on critical values of monitorable variables (e.g soil stability, plant interspace length, crust cover, exotic plant cover, etc.), which may signal an imminent transition. We will make the best estimates we can with the information we have. Since there's not much data on many ecosites, this is going to be tricky and involve some creativity. I'm sure you can appreciate that given your task. We are trying to develop a protocol for doing so on a gradient from data-rich to data-sparse to data-free scenarios. We will work on 16 ecosites, about half of which are represented in Utah Parks.

2) it turns out I made an error, I was trying to determine the relevancy of a dataset collected on the Paria Plateau to the Desert Sand ecosite. It turns out the soils up there are not Sandy Upland 6-10, they are 10-14. So I guess by extension they are an analog of Semi-desert sand, possibly with differences in blackbrush cover and obviously a bit wetter. But still these seem to all be pretty similar ecosystems, probably with most of the same key processes.

Steve Cassady:We here in AZ are currently working on updating both the MLRA 35 ecological sites you mention, the Sandy Upland found in the 6 - 10 inch precipitation zone and the Sandy Upland in the 10 - 14 inch precipitation zone. Ken Gishi, the team lead in our Holbrook Navajo Nation ESD office is leading that effort. We also would like to coordinate our efforts with you.