Modeling Past and Future Soil Moisture in Southern Colorado Plateau National Parks and Monuments

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In the semi-arid environment of the Colorado Plateau, soil moisture is an important driver of vegetation growth. The recent drought-related die-off of trees across the Southwest has highlighted how ecosystems may be vulnerable to changes in available water. Climate change models predict drier conditions over the next century.

How will these changes affect vegetation in these already dry ecosystems? The Southwest Biological Science Center of the U.S. Geological Survey (USGS) and the Southern Colorado Plateau Network of the National Park Service (NPS) have teamed up to answer this question. They used soil and vegetation data from ecosystems in nine network parks to model soil moisture under predicted climate conditions.

Their results predicted the amount of water that would be available to plants in the future. This information will help park managers to identify which plant communities may be at higher risk due to drought. This knowledge will enable scientists to develop strategies that will improve long-term ecosystem resistance and resilience, thus, helping to preserve our parks for future generations.

Photo of a grasslands landscape with shrubs in the background and mountains in the distance. Sky is full of fluffy clouds. Measuring tape is in the foreground.
Volcanic upland grassland ecosystem in Wupatki National Monument. Researchers modeled past and  future soil  moisture in this and 8 other national parks in the Southern Colorado Plateau Network.

NPS

Introduction

For this project, USGS and NPS scientists compared historical and predicted future climate data for nine Southern Colorado Plateau Network parks. They put this information into SoilWat2, a soil water model that takes information on soils and climate and translates it into an estimate of soil water availability. This estimate, or soil water potential (SWP), tells us how much water is available to plants for growth and survival.

Scientists determined SWP at 2 depths for each ecosystem: intermediate (20-50 cm) and deep (50-100 cm). They also looked at the amount of vegetation greenness, which represents plant growth, using satellite imagery over a 15-year period. For each ecosystem, they compared the SWP at both depths with the amount of greenness during a particular season. The depth at which SWP best correlated with plant growth represents the SWP that is most relevant to the dominant plants in each ecosystem. Results using this depth are presented in this report. For more details, please see the Methods section and the full resource brief for each park ecosystem.

This article presents the following for 13 ecosystems in nine national park units in the Southern Colorado Plateau Network of the National Park Service.

  • results of modeled current and future SWP
  • current and predicted future climate
  • relationship of NDVI to soil water potential

Methods

1. Data were collected from the following sources for input into the SoilWat2 model:

  • Texture and depth data from soil core samples that were taken during the establishment of SCPN upland monitoring plots (supplemented with soil texture data from soil surveys when the soil cores did not extend to the full depth of the soil profile).
  • Vegetation species and functional group cover data from SCPN monitoring plots
  • Daily weather data estimates (long-term historical weather) from 1920 to 2011 (Livneh et al. 2013)
  • Projected daily weather for the periods 2020–2059 and 2060–2099. All projected climate data was downloaded from the Green Data Oasis.

2. SoilWat2 integrated these climate data, along with the soils and vegetation data, to generate the following simulations:

  • long term historical daily soil water potential (1915-2010)
  • near term historical daily soil water potential (1980-2015)
  • near term future daily soil water potential (2020-2059)
  • long term future daily soil water potential (2060-2099)

We used box plots to represent annual variation in each of the seasonal soil moisture projections for the respective time periods (Figure 2B). For future time periods, we used the mean projected soil moisture. The SoilWat 2 model, along with the soil moisture simulations, is available at https://doi.org/10.5066/F7D50K6S.

3. Normalized difference vegetation index (NDVI) was generated bi-weekly from 2000-2014 using a neighborhood analysis of MODIS data. NDVI is an indicator of plant productivity and represents phenological timing in vegetation communities. NDVI ranges from 0 (low productivity) to 1 (high productivity).

4. We calculated annual NDVI by integrating the area under the NDVI curve as a representative measure of total annual productivity. Annual NDVI was then correlated with SWP averaged over windows ranging from 10 to 365 days throughout the year. This method of analysis allows us to look at the impact of timing and duration of water availability on annual NDVI.

Results

Present and future climate and soil moisture, and the relationship with NDVI for 13 ecosystems in nine SCPN national park units are presented here.

Landscape with shrubs in the foreground and hills in the background under a blue sky with a few scattered clouds.
Figure AL-1. Limy upland shrubland ecosystem in Aztec Ruins National Monument.

NPS

Study Area: Limy Upland Shrubland in Aztec Ruins National Monument, New Mexico

The limy upland shrubland plant community in Aztec Ruins National Monument (Figure A-1) consists of a mix of low shrubs, grasses and forbs with scattered overstory junipers. Common species include big sagebrush (Artemisia tridentata), galleta grass (Hilaria jamesii), snakeweed (Gutierrezia sarothrae), and Opuntia spp. Soils in this ecosystem are typically classified as loam. We used data from soil cores taken from six plots in this ecosystem as inputs to the SoilWat2 model.

The outputs from our model show soil water potential (SWP) for the past, present, and future, and highlight relatively moist and dry periods. Here we present seasonal and temporal patterns in soil water availability in the limy upland shrubland ecosystem in Aztec Ruins National Monument. 



Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer.  Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure AL-2: Historical (A) and future projections (B) of soil water potential (SWP) in the limy upland shrubland ecosystem in Aztec Ruins National Monument, New Mexico.

USGS

Figure AL-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the limy upland shrubland ecosystem in Aztec Ruins National Monument at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure AL-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure AL-3. Panel A - Seasonal climate patterns for Aztec Ruins NM; Panel B - monthly mean NDVI index; Panel C - correlations between NDVI and SWP; and Panel D - soil water potential (SWP) for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future time periods.

USGS

In Figure AL-3, Panel A presents the average seasonal patterns of climate in the limy upland shrubland ecosystem in Aztec Ruins National Monument. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B of Figure AL-3 presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014).

Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) (2001-2014). Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (10 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Limy Upland Shrubland Community in Aztec Ruins National Monument, is available here.

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Pinyon-juniper woodland with grassy understory.
Figure BP-1. Mesa-top pinyon-juniper woodland ecosystem in Bandelier National Monument.

NPS

Study Area: Mesa-Top Pinyon-Juniper Woodland in Bandelier National Monument, New Mexico

In the mesa-top pinyon-juniper woodland ecosystem in Bandelier National Monument (Figure BP-1), the overstory ranges from a dense to sparse canopy of oneseed junipers (Juniperus monosperma). The understory is also variable; the most common understory species include grama grass (Bouteloua gracilis) and snakeweed (Gutierrezia sarothrae). Soils in this ecosystem are typically classified as sandy loam. We used data from soil cores taken from 47 plots in this ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. Here we present seasonal and temporal patterns in soil water availability in the mesa-top pinyon-juniper woodland ecosystem in Bandelier National Monument.

Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer.  Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure BP-2: Historical (A) and future projections (B) of soil water potential (SWP) in the mesa-top pinyon-juniper woodland ecosystem in Bandelier National Monument.

USGS

Figure BP-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010. Panel B compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).
3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure BP-3. Panel A-Seasonal climate patterns for mesa-top pinyon-juniper woodlands in BAND; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential (SWP) for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future time period.

USGS

In Figure BP-3, Panel A presents the average seasonal patterns of climate for the mesa-top pinyon-juniper woodland ecosystem in Bandelier National Monument. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (12 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Mesa-Top Pinyon-Juniper Woodland Community in Bandelier National Monument, is available here.

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Expansive grassland under a blue sky with scattered clouds.
Figure CS-1. Sandy loam upland grassland ecosystem in Chaco Culture National Historical Park.

NPS

Study Area: Sandy Loam Upland Grassland in Chaco Culture National Historical Park

The sandy loam upland grassland ecosystem at Chaco Culture National Historical Park (CHCU) (Figure CS-1) is dominated primarily by blue grama (Bouteloua gracilis) and galleta grass (Hilaria jamesii) with scattered shrubs, including snakeweed (Gutierrezia sarothrae), four-wing saltbush (Atriplex canescens), and winterfat (Krascheninnikovia lanata). Soils in this ecosystem are typically classified as sandy clay loam. We used data from soil cores taken from 30 plots in this ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the sandy loam upland grassland ecosystem in CHCU.

: Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure CS-2. Historical (A) and future projections (B) of soil water potential (SWP) in the sandy loam upland grassland ecosystem in Chaco Culture National Historical Park.

USGS

Figure CS-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the sandy loam upland grassland ecosystem in Chaco Culture National Historical Park at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure CS-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure CS-3. Panel A-Seasonal climate patterns for the sandy loam upland grassland ecosystem in Chaco Culture National Historical Park; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential (SWP) for current (1970-2010) and near (2020-2059) and

USGS

In Figure CS-3, Panel A presents the average seasonal patterns of climate for the sandy loam upland grassland ecosystem in Chaco Culture National Historical Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (10 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Sandy Loam Upland Grassland in Chaco Culture National Historical Park is available here.

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Sandy shrubland with mountains in the distance
Figure GB-1. Desert sand shrubland ecosystem in the Bullfrog region of Glen Canyon National Recreation Area.

NPS

Study Area: Desert Sand Shrubland, Bullfrog Region of Glen Canyon National Recreation Area.

The desert sand shrubland ecosystem in the Bullfrog Region of Glen Canyon National Recreation Area (Figure GB-1) is generally characterized by sand-loving forbs like sand verbena (Abronia fragrans), and diverse shrubs such as Mormon-tea (Ephedra spp.), indigo bush (Psorothamnus fremontii), and sandsage (Artemisia filifolia). Soils in this ecosystem are typically classified as sandy. Another location where GLCA monitors the desert sand shrubland ecosystem is in the Escalante region, which is addressed separately. We used data from soil cores taken from six plots in the desert sand shrubland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability for the desert sand shrubland ecosystem in the Bullfrog region of Glen Canyon NRA.

Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure GB-2. Historical (A) and future projections (B) of soil water potential (SWP) in the desert sand shrubland ecosystem in the Bullfrog region of Glen Canyon NRA.

NPS

Figure GB-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the desert sand shrubland ecosystem in the Bullfrog region of Glen Canyon NRA at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure GB-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

- 3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future
Figure GB-3. Panel A-Seasonal climate patterns for the desert sand shrubland ecosystem in Glen Canyon NRA, Bullfrog; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure GB-3, Panel A presents the average seasonal patterns of climate for the desert sand shrubland ecosystem in the Bullfrog region of Glen Canyon NRA. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (10 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060–2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Desert Sand Shrubland, Bullfrog Region of Glen Canyon National Recreation Area, is available here.

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Large expanse of sandy shrubland with mountains in the distance.
Figure GH-1. Desert sand shrubland ecosystem in the Escalante region of Glen Canyon National Recreation Area.

NPS

Study Area: Desert Sand Shrubland, Escalante Region, Glen Canyon National Recreation Area.

The desert sand shrubland ecosystem in the Escalante region of Glen Canyon National Recreation Area (Figure GH-1) is generally characterized by diverse shrubs, including Mormon-tea (Ephedra spp.), Fremont’s indigo bush (Psorothamnus fremontii), blackbrush (Coleogyne ramosissima), and sandsage (Artemisia filifolia). Soils in this ecosystem are typically classified as sandy. Another location where GLCA monitors the desert sand shrubland ecosystem is in the Escalante region, which is addressed separately. We used data from soil cores taken from ten plots in the desert sand shrubland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability for the desert sand shrubland ecosystem in the Escalante region of Glen Canyon NRA.

Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure GH-2. Historical (A) and future projections (B) of soil water potential (SWP) in the desert sand shrubland ecosystem in the Escalante region of Glen Canyon NRA.

USGS

Figure GH-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the desert sand shrubland ecosystem in the Escalante region of Glen Canyon NRA at deep soil depths (50-100 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure GH-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure GH-3. Panel A-Seasonal climate patterns for desert sand shrubland in Glen Canyon NRA, Escalante region; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; Panel D-soil water potential (SWP) for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure GH-3, Panel A presents the average seasonal patterns of climate for the desert sand shrubland ecosystem in the Escalante region of Glen Canyon NRA. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (325 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060–2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Desert Sand Shrubland, Escalante Region of Glen Canyon National Recreation Area, is available here.

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A woodlan of mostly pinyon and some juniper trees.
Figure GP-1. Pinyon-juniper woodland ecosystem in Grand Canyon National Park.

NPS

Study Area: Pinyon-Juniper Woodland Community in Grand Canyon National Park

The pinyon-juniper woodland community in Grand Canyon National Park (GRCA) (Figure GP-1) is characterized by a dense pinyon-juniper overstory with understory shrubs including Stansbury cliffrose (Purshia stansburiana) and big sagebrush (Artemisia tridentata). Perennial grasses, forbs and cacti are also represented. Soils in this ecosystem are typically classified as clay loam. We used data from soil cores taken from 22 plots in this ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the pinyon-juniper woodland ecosystem at GRCA.

Two part graph. Left: Line graph of soil water potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure GP-2. Historical (A) and future projections (B) of soil water potential (SWP) in the pinyon-juniper woodland ecosystem at Grand Canyon National Park.

USGS

Figure GP-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the pinyon-juniper woodland ecosystem at Grand Canyon National Park at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure GP-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

- 3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future
Figure GP-3. Panel A-Seasonal climate patterns for pinyon-juniper woodland ecosystem at Grand Canyon NP; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure GP-3, Panel A presents the average seasonal patterns of climate for the pinyon-juniper woodland ecosystem at Grand Canyon National Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (10 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Pinyon-Juniper Woodland Community in Grand Canyon National Park, is available here.

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Pinyon-juniper woodland under a blue sky.
Figure ML-1. Loamy mesa-top pinyon-juniper woodland ecosystem in Mesa Verde National Park

NPS

Study Area: Loamy Mesa-Top Pinyon-Juniper Woodland in Mesa Verde National Park

The loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park (Figure ML-1) is characterized by a dense pinyon-juniper (Pinus edulis-Juniperus spp.) overstory and an understory dominated by muttongrass (Poa fendleriana) and antelope bitterbrush (Purshia tridentata). Forbs and cacti are also present. Soils in this ecosystem are typically classified as clay loam. A second ecosystem that the Southern Colorado Plateau Network monitors in Mesa Verde NP is the shallow loamy mesa-top pinyon-juniper woodland, which is addressed in a separate brief. We used data from soil cores taken from 31 plots in the pinyon-juniper mesa-top woodland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the loamy mesa-top pinyon-juniper woodland in Mesa Verde NP.

Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure ML-2. Historical (A) and future projections (B) of soil water potential (SWP) in the loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park.

USGS

Figure ML-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure ML-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

Four graphs: 3A-Current & predicted temperature, precipitation; 3B-Monthly mean NDVI (2001–2014); 3C- periods when soil moisture related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure ML-3. Panel A-Seasonal climate patterns in loamy mesa-top pinyon-juniper woodlands in Mesa Verde NP. Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and soil water potential (SWP); Panel D-SWP for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure ML-3, Panel A presents the average seasonal patterns of climate for the loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (119 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Loamy Mesa-Top Pinyon-Juniper Woodland in Mesa Verde National Park, is available here.

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Dense pinyon-juniper woodland with bare soils and gnarled tree trunks in the foreground.
Figure MS-1. The Shallow Loamy Mesa-Top Pinyon-Juniper Woodland ecosystem in Mesa Verde National Park.

Study Area: Shallow Loamy Mesa-Top Pinyon-Juniper Woodland in Mesa Verde National Park

The shallow loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park (Figure MS-1) is characterized by a dense pinyon-juniper (Pinus edulis-Juniperus spp.) overstory and an understory dominated by muttongrass (Poa fendleriana) and antelope bitterbrush (Purshia tridentata). Forbs and cacti are also present. Soils in this ecosystem are typically classified as a loamy. These shallow soils often occur on the mesa shoulders. The Southern Colorado Plateau Network also monitors the pinyon-juniper mesa-top woodland in the park, which is addressed in a separate brief. We used data from soil cores taken from ten plots in the shallow loamy mesa-top pinyon-juniper woodland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the shallow loamy mesa-top pinyon-juniper woodland in Mesa Verde NP.

Two part graph. Left: Line graph of soilwater potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soilwater potential by season for the current), near future and long-term future.
Figure MS-2. Historical (A) and future projections (B) of soil water potential (SWP) in the shallow loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park

USGS

Figure MS-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the shallow loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure MS-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

Four graphs: 3A-Current & predicted temperature, precipitation; 3B-Monthly mean NDVI (2001–2014); 3C- periods when soil moisture related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure MS-3. Panel A-Seasonal climate patterns in the shallow loamy mesa-top pinyon-juniper woodlands in Mesa Verde NP. Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and soil water potential (SWP); Panel D-SWP for current (1970-2010) and near (2020-2059) and long-term (2060-2099

USGS

In Figure MS-3, Panel A presents the average seasonal patterns of climate for the shallow loamy mesa-top pinyon-juniper woodland in Mesa Verde National Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (119 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Shallow Loamy Mesa-Top Pinyon-Juniper Woodland in Mesa Verde National Park, is available here.

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Monitoring tape running through an expansive grassland
Figure PC-1. Clayey fan grassland ecosystem at Petrified Forest National Park, Arizona.

NPS

Study Area: Clayey Fan Grassland in Petrified Forest National Park, Arizona

Clayey fan grassland is one of two upland ecosystems that the Southern Colorado Plateau Network (SCPN) monitors at Petrified Forest National Park (Figure PC-1). This open grassland community is primarily dominated by the grass, alkali sacaton (Sporobolus airoides), and the shrub, four-wing saltbush (Atriplex canescens). Annual grasses and forbs are well represented in wet years. Soils in this ecosystem are typically classified as sandy clay loam. The other ecosystem monitored by SCPN is the sandy loam upland grassland, which is addressed in a separate brief. We used data from soil cores taken from 30 plots in the clayey fan grassland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. Here we present seasonal and temporal patterns in soil water availability in the clayey fan grasslands ecosystem at Petrified Forest National Park.

Panel A (left) shows historical spring, summer and fall/winter Soil Water Potential for clayey fan grasslands at Petrified Forest NP. Panel B shows current, near, and long-term future Soil Water Potential for the 3 seasons.
Figure PC-2: Historical (A) and future projections (B) of soil water potential (SWP) in the clayey fan grassland ecosystem at Petrified Forest National Park, Arizona.

USGS

Figure PC-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010. Panel B compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

Figure PC-3. (From top to bottom) Panel A - Seasonal climate patterns for Petrified Forest NP; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; Panel D-soil water potential (SWP) for current, near future, and long-term future.
Figure PC-3. Panel A - Seasonal climate patterns for Petrified Forest NP; Panel B - monthly mean NDVI index; Panel C - correlations between NDVI and SWP; and Panel D - soil water potential (SWP) for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future time periods.

USGS

In Figure PC-3, Panel A presents the average seasonal patterns of climate for clayey fan grasslands in Petrified National Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (11 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Clayey Fan Grassland Community in Petrified Forest National Park, is available here.

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: Expansive grassland with bare ground visible under a blue sky with scattered clouds.
Figure PS-1. Sandy loam upland grassland ecosystem in Petrified Forest National Park.

NPS

Study Area: Sandy Loam Upland Grassland Community in Petrified Forest National Park

The sandy loam upland grassland ecosystem at Petrified Forest National Park (PEFO) (Figure PS-1) is characterized by blue grama (Bouteloua gracilis), galleta grass (Hilaria jamesii) and perennial dropseed (Sporobolus spp.). Scattered four-wing saltbush (Atriplex canescens) and other shrubs are present. Soils in this ecosystem are typically classified as ranging from sandy loam to sandy clay loam. SCPN also conducts long-term monitoring in the clayey fan grassland ecosystem in PEFO, which is addressed in a separate brief. We used data from soil cores taken from 30 plots in the sandy loam upland grassland ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the sandy loam upland grassland ecosystem in PEFO.

Historical (A) and future projections (B) of soil water potential (SWP) in the sandy loam upland grassland ecosystem in Petrified Forest National Park.
Figure PS-2. Historical (A) and future projections (B) of soil water potential (SWP) in the sandy loam upland grassland ecosystem in Petrified Forest National Park.

USGS

Figure PS-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the sandy loam upland grassland ecosystem in Petrified Forest National Park at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure PS-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure GP-3. Panel A-Seasonal climate patterns for sandy loam upland grasslands at Petrified Forest NP; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure PS-3, Panel A presents the average seasonal patterns of climate for the sandy loam upland grassland ecosystem in Petrified Forest National Park. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (41 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Sandy Loam Upland Grassland Community in Petrified Forest National Park, is available here.

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Extensive grassland under a blue sky with hill in the background.
Figure PP-1. Malpais grassland ecosystem in Petroglyph National Monument.

NPS

Study Area: Malpais Grassland Ecosystem in Petroglyph National Monument

The Malpais grassland ecosystem in Petroglyph National Monument (PETR) (Figure PP-1) is dominated by black grama (Bouteloua eriopoda) and other shortgrass bunchgrasses including galleta grass (Hilaria jamesii), sand dropseed (Sporobolus cryptandrus) and needlegrass (Hesperostipa neomexicana). Winterfat (Krascheninnikovia lanata) is the most abundant shrub. Soils in this ecosystem are typically classified as sandy clay loam. We used data from soil cores taken from six plots in this ecosystem as inputs to the SoilWat2 model.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the Malpais grassland ecosystem in Petroglyph National Monument.

Two part graph. Left: Line graph of soil water potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soil water potential by season for the current, near future and long-term future.
Figure PP-2. Historical (A) and future projections (B) of soil water potential (SWP) in the Malpais grassland ecosystem in Petroglyph National Monument.

USGS

Figure PP-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the Malpais grassland ecosystem in Petroglyph National Monument at deep soil depths (50-100 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure PP-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure PP-3. Panel A-Seasonal climate patterns for Malpais grassland ecosystem in Petroglyph National Monument; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure PP-3, Panel A presents the average seasonal patterns of climate Malpais grassland ecosystem in Petroglyph National Monument. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (10 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Malpais Grassland Community in Petroglyph National Monument, is available here.

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Extensive grassland under a blue sky with shrubby hills in the background.
Figure WL-1. Volcanic upland grassland ecosystem in Wupatki National Monument.

NPS

Study Area: Volcanic Upland Grassland in Wupatki National Monument

The volcanic upland grassland ecosystem in Wupatki National Monument (WACA) (Figure WL-1) is dominated by galleta grass (Hilaria jamesii) and black grama (Bouteloua eriopoda). Annual forbs like narrow-leaf goosefoot (Chenopodium leptophyllum) and Russian thistle (Salsola tragus) are sometimes abundant. Soils in this ecosystem are typically classified as sandy clay loam. We used data from soil cores taken from six plots in this ecosystem as inputs to the SoilWat2 model. The volcanic upland grassland is one of two upland ecosystems that SCPN monitors at WUPA. The second is the mixed sandstone shrubland, which is addressed in a separate brief.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the volcanic upland grassland ecosystem in Wupatki National Monument.

Two part graph. Left: Line graph of soil water potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soil water potential by season for the current, near future and long-term future.
Figure WL-2. Historical (A) and future projections (B) of soil water potential (SWP) in the volcanic upland grassland ecosystem in Wupatki National Monument.

USGS

Figure WL-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the volcanic upland grassland ecosystem in Wupatki National Monument at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure WL-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future.
Figure WL-3. Panel A-Seasonal climate patterns for volcanic upland grassland ecosystem in Wupatki National Monument; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI & SWP; Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) future.

USGS

In Figure WL-3, Panel A presents the average seasonal patterns of climate Volcanic upland grassland ecosystem in Wupatki National Monument. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (96 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Volcanic Upland Grassland Community in Wupatki National Monument, is available here.

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Extensive shrubland with hills and mountains in the distance.
Figure WS-1. Loamy upland shrubland ecosystem in Wupatki National Monument.

NPS

Study Area: Loamy Upland Shrubland in Wupatki National Monument

The loamy upland shrubland ecosystem in Wupatki National Monument (WACA) (Figure WS-1) is characterized by large areas of galleta grass (Hilaria jamesii) interspersed with shrubs, primarily Apache plume (Fallugia paradoxa), Mormon-tea (Ephedra torreyana), and sand sage (Artemisia filifolia). Soils in this ecosystem are typically classified as a sandy loam, with a large gravel component. We used data from soil cores taken from 30 SCPN monitoring plots in the mixed sandstone ecosystem as inputs to the SoilWat2 model. The loamy upland shrubland is one of two upland ecosystems that SCPN monitors at WUPA. The second is the volcanic upland grassland ecosystem, which is addressed in a separate brief.

The outputs from our model show SWP for the past, present, and future, and highlight relatively moist and dry periods. These data can be considered in a variety of ways, including climate variability, variability among soil profiles, and relationships with plot-based vegetation monitoring data. Here we present seasonal and temporal patterns in soil water availability in the loamy upland shrubland ecosystem in Wupatki National Monument.

Two part graph. Left: Line graph of soil water potential by season (1920 to 2000). Seasons are: Fall/Winter, Spring and Summer. Right: Box plot of soil water potential by season for the current, near future and long-term future.
Figure WS-2. Historical (A) and future projections (B) of soil water potential (SWP) in the loamy upland shrubland ecosystem in Wupatki National Monument.

USGS

Figure WS-2 presents historical (panel A) and future (panel B) projections of soil water potential (SWP) for the loamy upland shrubland ecosystem in Wupatki National Monument at intermediate soil depths (20-50 cm) for three seasons: fall & winter (October-February), spring (March-June), and summer (July-September). Panel A shows historical annual variability (fine lines) and moving 10-year averages (thick lines) of drying and wetting from 1915-2010.

Panel B of Figure WS-2 compares seasonal SWP among three time periods: current (C; 1970-2010), near future (N; 2020-2059), and long-term future (L; 2060-2099). Boxplot whiskers are 1.5 times the inter-quartile range of values while dots are values outside this range. Dashed lines in both panels highlight plant-relevant SWP levels: traditional wilting point (-1.5MPa) and a drylands wilting point (-3.0MPa; Kolb and Sperry, 1999a, 1999b).

- 3A-Current and predicted temperature and precipitation; 3B-Monthly mean for NDVI (2001–2014); 3C- periods when soil moisture is related to changes in vegetation productivity; 3D-Average daily SWP for the current period, near future, and long-term future
Figure WS-3. Panel A-Seasonal climate patterns for the loamy upland shrubland ecosystem in Wupatki National Monument; Panel B-monthly mean NDVI index; Panel C-correlations between NDVI and SWP; and Panel D-soil water potential for current (1970-2010) and near (2020-2059) and long-term (2060-2099) fu

USGS

In Figure WS-3, Panel A presents the average seasonal patterns of climate the loamy upland shrubland ecosystem in Wupatki National Monument. The climate diagram (Walter and Leith 1967) shows the mean monthly temperature (◦C) and precipitation (mm) in dark red and blue lines, respectively, in the current period (1970-2010). Shaded red and blue areas indicate the range of potential values in the near (darker area; 2020-2059) and long-term (lighter area; 2060-2099) future periods. Mean annual temperature (MAT) and mean annual precipitation (MAP) are derived from the mean monthly values.

Panel B presents the monthly mean for normalized difference vegetation index (NDVI, 2001-2014). Panel C presents the seasonal periods when soil moisture is related to fluctuations in vegetation productivity, which is depicted by correlations between NDVI and soil water potential (SWP) 2001-2014. Colors indicate the sum of significant correlations (p < 0.1) that overlap with each day of the year based upon window length (32 days identified as the most significant interval length). Darker blue indicates periods of greater cumulative correlation between NDVI and SWP.

Finally, in Panel D, average daily SWP for the current period (1970-2010; black), near future (2020–2059; yellow), and long-term future (2060– 2099; purple) are presented. For future time-periods, thick lines represent the median value among climate models, while shaded areas represent the range of values across different climate models.

The full resource brief, Describing Past and Future Soil Moisture in the Loamy Upland Shrubland Community in Wupatki National Monument, is available here.

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References

Kolb, K. J., and J. S. Sperry. 1999a. Differences in drought adaptation between subspecies of sagebrush (Artemisia tridentata). Ecology, 80:2373–2384.

Kolb, K. J., and J. S. Sperry. 1999b. Transport constraints on water use by the great basin shrub, Artemisia tridentata. Plant, Cell and Environment, 22:925–935.

Livneh B., E. A. Rosenberg, C. Lin, B. Nijssen, V. Mishra, K. M. Andreadis, E. P. Maurer, and D. P. Lettenmaier. 2013. A Long-Term Hydrologically Based Dataset of Land Surface Fluxes and States for the Conterminous United States: Update and Extensions, Journal of Climate, 26, 9384–9392.

Walter, H., and H. Leith. 1967. Climate diagram world atlas. Fischer Verlag, Jena, Thuringia, Germany.

Last updated: October 15, 2018