Please skim the revised state-and-transition model just enough to refresh your memory if you completed a phase 1 survey. If this is your first survey, and the first time you’ve seen a version of this model, please take the time to review it in depth. This model has been reviewed and revised according to responses to the phase 1 survey. Pay special attention to the section “modifications” (in red), and then please answer question 1.
[revised model will appear here]
Question
1) Please estimate your overall confidence that this model, which takes into account proposed modifications from previous surveys, is the correct model of the most important ecosystem states, processes and dynamics of the ecosite in question.
[Please answer on a subjective scale of 0 – 100% certainty. Enter any value in this range. To help you answer: 0% means “It’s anyone’s guess, this model is no better than any other model”, 50% means “Because this model is reasonable I would tend to believe it until evidence to the contrary is presented”, 100% means “The model is so well-supported by evidence and accumulated knowledge, that I am certain it is correct.” If you answered this question in a phase 1 survey, and your answer is the same, you do not need to answer. ]
BACKGROUND/ EXPLANATION OF PHASE 2 SURVEY
This survey is designed to estimate critical cutoff points in key indicators which may signal a transition in progress. Please refer to Figure 2. In the limey uplands ecosite, from a management standpoint, we are concerned with the sequence of changes that results in loss of fire and savannization of grassland ecosystems, and our model can be simplified to represent just these dynamics (Fig. 2). Within a given state, the system may exhibit considerable dynamics and variability in response to drivers such as grazing, fire management, and climate variability. The system is considered to be resilient as long as it retains the capacity to maintain or recover key structural and functional properties of the current state. If the system is on a trajectory toward a new state (i.e., one characterized by fundamentally different structural and functional properties), management may avert a state transition if passive restoration (e.g., cessation of grazing or fire suppression) are implemented while the system still retains resiliency. Managers who wish to avert an undesirable state transition can define the quantitative value or range of values that trigger implementation of passive restoration. Such management trigger values can be described as preventative thresholds and established on the basis of one or more key monitoring variables that are related to the ecological processes that underlie the undesirable state transition. It is important to recognize that there is no one single value that can be determined for a particular preventative threshold. Key considerations in estimating the preventative threshold are (1) that the preventative threshold must trigger management action while the system still retains resiliency, (2) that the preventative threshold be established to account for potential lag effects both in actual management implementation and in ecological response, and (3) that the preventative threshold account for the potential occurrence of extreme climatic events or other factors which may unexpectedly and rapidly result in loss of system resilience to factors under the control of management.
If resilience is exceeded prior to the implementation of passive restoration, then the system will not have the capacity to recover its original structure and function without the imposition of active restoration (such as seeding or vegetation manipulation, or controlled burning) by management. At this point, a state transition has occurred and the system has crossed a restoration threshold when simple passive restoration practices are no longer effective and active restoration is required to recover properties of the original state. This second type of threshold can also be defined by the quantitative value or range of values of one or more key monitoring variables.
Fig. 2. Simplification of a key transition sequence from the above model (Fig. 1), illustrating two types of thresholds, preventative, and restoration which can be estimated based on values of key indicators.
For Transition 5, we will present you with several relevant indicators and prompt you to answer 6 questions. To keep the model broad, the indicators apply to the whole Limy uplands ecosite, inside and outside of Wupatki, and encompassing different grazing and fire suppression regimes.
Indicators
I1. Stocking rate. An allotment-scale measure of grazing pressure. May trigger T5 if high enough.
I2. Density of cowpies. A site-scale measure of grazing pressure. May trigger T5 if high enough.
I3. Length of rest from grazing. If high enough, may reverse T5, as long as T5 has not progressed beyond restoration threshold.
I4. Time since fire. A site-scale measure of either grazing-triggered reduction of fuels, or fire suppression practices. May trigger T5 if high enough.
I5. Total plant cover. An easy to measure surrogate for biomass, i.e. fuel load. Decreases as T5 progresses.
I6. Basal plant cover + litter. An index related both to amount and connectivity of fuel. Decreases as T5 progresses.
I7. Average length of bare patches. An inverse measure of fuel connectivity. A bare patch is devoid of plant basal cover or litter. Increases as T5 progresses.
I8. Average length of combustible patches. A measure of connectivity. Decreases as T5 progresses.
Fig. 3. An illustration of measuring combustible patch length. Dashed line represents length.
I9. Number of trees per hectare. A measure of colonization rates, and a glimpse of the future if trees mature. Increases as T5 progresses.
I10. Average tree height. A measure of resistance to fire. Increases as T5 progresses, may signal completion of transition.
For each indicator we will ask you to estimate the preventative threshold point, and the restoration threshold point in the specified units. Answer based on past experience, accumulated knowledge, and general principles.We do not expect anyone to know the answer, we are collecting opinions and educated guesses. If you wish, you may consult a data source that you are already aware of, but we do not expect you to undertake an extensive literature review to find new information. As a reference, to help you get within the ballpark, we have provided estimates of current status of monitoring plots, or other useful reference points, when available. You may interpret “current status” as belonging to whichever state or phase you think is correct. Don’t be worried if you don’t have much confidence in your estimate, you will also be asked to rate your confidence in your estimate, and your confidence in anyone’s estimate. Confidence will be taken into account, and will be a part of the final product.
Please answer the following questions for each indicator in the table provided below, where appropriate. *** indicates required questions:
QUESTIONS
For questions 2 and 2, we’d like you to try and complete at least 50% of the response table, even if your confidence in your answers is low. The more complete it is, the better. If you truly have no idea whatsoever about the answer to a particular question (~ 0% confidence), you may leave it blank, but please try if you can.
***2) Please estimate the preventative threshold, the point at which transition is likely to be initiated, and imminent if no passive restoration measures are taken. Please answer in appropriate units in table below.
***3) Please estimate the restoration threshold, the point at which transition is imminent even if passive restoration is undertaken. Please answer in appropriate units in table below.
4) Would you add any indicators to this list that would be crucial in tracking transition 5? If so please type in the indicator (in the “other indicator” cells) and units in appropriate boxes in the table below, and provide your preventative and restoration threshold estimates there.
***5) Overall, please estimate your confidence in your threshold estimates, including any provided in question 4.
[Please answer on a subjective scale of 0 – 100% certainty. Enter any value in this range. To help you answer: 0% means “It’s anyone’s guess, these estimates are no better than any other estimates”, 50% means “Because these estimates are reasonable I would tend to believe them until evidence to the contrary is presented”, 100% means “The estimates are so well-supported by evidence and accumulated knowledge, that I am certain it is correct.”]
***6) Please take a moment to think of any scientist or other person, who is to your knowledge the best qualified to estimate the values you estimated in questions 1 & 2. This person could be yourself, or any other person. “Best” qualified may or may not mean highly qualified; sometimes no one is highly qualified. Now, in the hypothetical scenario that this person had made these estimates, using all of the data, knowledge and experience available to them, estimate how much confidence you would have that they are the correct values.
[use the same scale as question 3, 0-100%]
7) Now please consider, for any individual threshold estimates you provided, if any of the values of “confidence in your own estimate”, or “confidence in anyone’s estimates” differ from the answers to questions 5 and 6. Fill them into the table below.
Response matrix. Required answers are indicated in yellow, try to fill in at least 50% of these. Cells filled in black require no answers.
*AUM = animal unit months, a typical unit of stocking rate. If 3 cows each graze for 6 months, this constitutes (3 * 6) 18 AUMs. Usually expressed on a per area basis, e.g. acre-1 in the United States.
** The current stocking rate in the national monument has been 0 since 1989. For reference, these estimates were provided by CP Bar ranch directly to the North of Wupatki which is currently grazed.
*** note: this estimate is the mean length between basal plant cover, it does not take into account litter as does our proposed indicator. Mean length between basal plant cover and/or litter patches would be smaller.
Thank you for taking time out of your schedule to complete this questionnaire, we greatly appreciate your input!
Please let us know if you would be willing to do the same type of survey for additional ecosites which might fall under your area of expertise.
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