1. My spatial problem

• A description of the research question that you are exploring.

Research question: How is the spatial pattern of juniper density (A) related to the spatial pattern of slope, aspect, and a combination of the two (B) via soil moisture and solar radiation?

The expansion of western juniper has become a concern in many rangeland areas, and is associated with a number of ecological and hydrological impacts [1,2]. The study site is located in a semiarid watershed in central OR, and was established to assess ecohydrological characteristics associated with juniper expansion and removal. The majority of western juniper was removed from this watershed in 2005 -2006 and juniper saplings have become re-established in this area. The objectives of this project are 1) to determine the relationship between the density of western juniper sapling re-establishment and slope and aspect in this watershed and 2) assess density changes in vegetation cover at this watershed since juniper removal.

The intent of this project is also to establish a methodology that will be expanded to include patterns of soil moisture, soil surface temperature, and soil type (but additional data needs to be collected). While juniper density and vegetation cover for the purposes of this project are the dependent variables, in the future I am exploring how certain ecohydrological characteristics vary with juniper density.

• A description of the dataset you will be analyzing, including the spatial and temporal resolution and extent.

A combination of National Agriculture Imagery Program (NAIP), unmanned aerial vehicle (UAV) imagery, and ground-based data will be used. Forty-one belt transects (3m by 30m) representing areas of varying aspect and slope were conducted in summer of 2018 to assess juniper density across the entire watershed.  UAV-based multispectral imagery (red, green, blue, red-edge, and near-infrared bands) was collected at a study plot in the watershed in October 2018, but needs to be expanded to represent topography of the watershed. Resolution of the UAV imagery is approximately 2.5cm/pixel. NAIP imagery (1 m resolution) will be used to assess density over time. A 10 m digital elevation model (DEM) will be used to model the topography of the watershed. Alternatively, a higher-resolution DEM created from UAV imagery may be used if it is available. Prior to analysis, support vector machine (SVM) supervised classification will be used to identify juniper in the UAV and NAIP imagery and to assess overall vegetation cover in NAIP imagery. It should be noted that while I have used SVM classification successfully with multispectral UAV imagery to assess juniper density (shown in the figure below), the accuracy of this process will need to be assessed with the NAIP data as there is a large difference in spatial resolution (2.5 cm compared to 1 m). If I am unable to identify juniper successfully in NAIP imagery, then only UAV and ground-based data will be used to assess juniper density.

• Hypotheses: predict the kinds of patterns you expect to see in your data, and the processes that produce or respond to these patterns.

I expect that juniper density will be positively related to north aspects and negatively related to slope angle as these characteristics promote higher levels of soil moisture. However, these patterns may vary with both soil type and amount of non-juniper vegetation cover.  Similar to past studies [2], we may anticipate that overall vegetation cover may change at this watershed in response to the removal of juniper. Changes in vegetation cover associated with juniper density may be related to juniper transpiration, soil moisture, and canopy interception.

• Approaches: describe the kinds of analyses you ideally would like to undertake and learn about this term, using your data.

Initially, I will assess the spatial pattern of slope, aspect, and a combination of the two in the watershed. Further, the relationship between observed juniper density and the slope angle and aspect characteristics associated with highest soil moisture will be assessed. I would like to integrate the NAIP imagery, DEM, transect data, and UAV imagery for analysis of juniper density. During this term, this model will focus on slope and aspect but I would like to establish a model that I can expand to use to assess other characteristics as well (such as soil moisture, soil temperature, and vegetation cover).  Using the NAIP imagery, I would like to see assess temporal changes in vegetation cover. In particular, I am interested in understanding how to best use data with different resolutions and how to expand this methodology for more complicated analysis in future research.

• Expected outcome: what do you want to produce — maps? statistical relationships?

I would like to create maps characterizing juniper density within the watershed and determine if there is a statistical relationship between juniper density and slope and aspect (that can be expanded as more variables are addressed). Additionally, I would like to assess changes in total vegetation cover over time in this watershed.

• How is your spatial problem important to science? to resource managers?

The expansion of western juniper is associated with a number of ecohydrological changes, to include reduced undercanopy soil moisture [3], reduced productivity[4] and increased erosion[5]. The removal of western juniper is labor intensive and expensive, and can be difficult to implement. An improved understanding of the spatial patterns associated with juniper re-establishment after removal can be used to target treatment when appropriate but also to improve our understanding of the ecohydrologic impacts of juniper expansion within these communities. This analysis can also provide information about which areas are at greatest risk based on topography. Additionally, understanding changing in vegetation cover helps to determine the timing and impacts of removal. While beyond the scope of this project, this information may be used to determine how the rate of juniper expansion relates to other ecohydrological characteristics over time.

2. Your level of preparation: how much experience do you have with (a) Arc-Info, (b) Modelbuilder and/or GIS programming in Python, (c) R, (d) image processing, (e) other relevant software

• I have used ArcMap/Pro a moderate amount in a classroom setting (GIS 1&2, GIS in water resources), for independent research, and in the workplace. Outside of a classroom setting, I have largely used ArcInfo for map creation and geospatial analysis (primarily unsupervised and supervised classification).
• I have used Modelbuilder a limited amount, and it has largely been limited to class assignments in Geog 560/561. I do not have experience with GIS programming in Python.
• I have some experience using R, primarily for basic statistical analysis. I have no experience using R for spatial statistics.
• I have limited experience using ENVI, but I would need to refresh the basic procedures. I do not have experience with MATLAB.
• I have some experience with Google Earth Engine, although I would need to review the basics to be effective.

References

1. Coultrap, D.E.; Fulgham, K.O.; Lancaster, D.L.; Gustafson, J.; Lile, D.F.; George, M.R. Relationships between western juniper (Juniperus occidentalis) and understory vegetation. Invasive Plant Sci. Manag. 2008, 1, 3–11.
2. Dittel, J.W.; Sanchez, D.; Ellsworth, L.M.; Morozumi, C.N.; Mata-Gonzalez, R. Vegetation response to juniper reduction and grazing exclusion in sagebrush-steppe habitat in eastern Oregon. Rangel. Ecol. Manag. 2018, 71, 213–219.
3. Lebron, I.; Madsen, M.D.; Chandler, D.G.; Robinson, D.A.; Wendroth, O.; Belnap, J. Ecohydrological controls on soil moisture and hydraulic conductivity within a pinyon-juniper woodland. Water Resour. Res. 2007, 43, W08422.
4. Miller, R.F.; Svejcar, T.J.; Rose, J.A. Impacts of western juniper on plant community composition and structure. J. Range Manag. 2000, 53, 574–585.
5. Reid, K.; Wilcox, B.; Breshears, D.; MacDonald, L. Runoff and erosion in a pinon-juniper woodland: Influence of vegetation patches. Soil Sci. Soc. Am. J. 1999, 63, 1869–1879.