Who Grows There? Analyzing Montane Meadow Vegetation as an Indicator of Hydrologic Stress Ryuko Novak-Murano, Dr. Hillary Jenkins ryuko_novak-murano@redlands.edu University of Redlands, Department of Environmental Studies, 1200 E. Colton Ave, Redlands, CA 92374
II. Classifying Vegetative Communities
Abstract/Background Montane meadows are biodiversity hotspots, hosting unique annual and perennial vegetation, small mammals, arthropods, and a robust community of pollinators. Because meadows respond to natural and anthropogenic stressors, they serve as near real-time indicators of the ecological impacts of climate change. Vegetative communities in meadows are the surface expression of numerous environmental factors, including soil, climate, and hydrology, and their relationships. Most existing environmental research on subalpine meadow ecosystems has been conducted on meadows in the Sierra Nevada mountains. Here, we examine vegetation distribution at three meadow sites (Lodgepole, Bluff, and Broomflat) in the San Bernardino National Forest and compare this with underlying hydrology (characterized by depth to groundwater), enriching our understanding of unique ecosystems in the Inland Empire. Species richness, vegetation identification and type, maximum and minimum height, and percent bare ground were collected across 1x1 yard plots within each meadow. Vegetation composition data was then used to generate a wetland indicator species distribution for each meadow based on the National Wetland Plant List available via the US Army Corps of Engineers (USACE) and the US Department of Agriculture (USDA) Plants Database. The smallest meadow, Lodgepole, is dominated by facultative forb and grass species and exhibits traits of a hydrologically healthy wet meadow that is experiencing cyclical drought stress. The intermediate meadow, Bluff, is mainly sedge and grass species returning to a recharging water table (indicated by the resurgence of Bluff Lake). The largest meadow, Broomflat, is also the driest, having a notable proportion of shrubs as well as facultative wetland rushes concentrated around one small pond. Understanding the relationship between vegetation and hydrology in threatened meadow ecosystems provides an important basis for understanding how shifting climates will impact these vital systems.
NWPL Indicator Classes
Vegetation Typing
Water Availability and Species Abundance
Meadow Vegetation were classified by their NWPL Indicator Status to determine plant and community-level water needs. Indicator Status
Figure 2. Stacked Bar Chart of the frequency of 5 major vegetation types (Rush, Sedge, Forb, Grass, and Shrub) across Bluff, Lodgepole, and Broomflat
Ecological Description Lichvar and Minkin (2008)
% Expected Occurrence in Wetland Habitats
Obligate Wetland
OBL (1)
Almost always a hydrophyte, rarely in uplands
99
Facultative Wetland
FACW (2)
Usually is a hydrophyte but occasionally found in uplands
67-99
Facultative
FAC (3)
Commonly occurs as either a hydrophyte or non-hydrophyte
34-66
Facultative Upland
FACU (4)
Occasionally is a hydrophyte, but usually occurs in uplands
1-33
Upland
UPL (5)
Rarely is a hydrophyte, almost always occurs in uplands
1
1. Rushes: family Juncaceae 2. Sedges: family Cyperaceae 3. Forbs: various families of leafy, non-woody herbs 4. Grasses: family Poaceae 5. Shrubs: various families of woody, bush-like plants
I. Methodology
A Figures 3A and B. Diagram (3A) depicting National Wetland Plant List wetland regimes relative to surface water availability (US Army Corps of Engineers). Wetland Delineation Model (3B) courtesy of Penn State (2017).
Wetland Species Distribution
•
Bluff
Lodgepole
Drier vegetation (FAC and FACU species) was more prevalent in the Western regions of Broomflat and the Eastern regions of the BluffLodgepole system
Broomflat
•
Figures 4 and 5. NWPL class distribution in Broomflat (left panel), Lodgepole and Bluff Meadows (right panel).
Species Richness vs. Water Table Depth
Field Methods • Measured 1 x 1-yard plots proximal to piezometer (groundwater well) sites • Estimated bare ground within plots • Counted plant species within plots • Measured min and max vegetation heights • Extracted samples for herbarium collection
Lab Methods • •
• •
Processed data using Excel to identify correlations Identified species and assigned dominant species' water needs (NWPL indicator status) Used ArcGIS Pro to map spatial trends Pressed and dried field specimens, mounted dried plant pressings in an herbarium
B
Wetland Species Counts
B
III. Spatial Analysis
A
Figure 8. Scatterplot of Depth to Water versus Species Count in Bluff (left panel) and Lodgepole (right panel).
•
As Lodgepole becomes drier, species richness declines, but as Bluff becomes drier, species richness increases
•
Lodgepole’s wet species are dying while prolonged drying in Bluff has allowed expansion of drought tolerant species
•
A higher proportion of dry (FACU) species versus wet (OBL) species suggests that wetland species may be more vulnerable to drought
NWPL values were assigned for each species/vegetation type found across each meadow site.
Common Vegetation Types Found in Meadows
Figure 1. Photographs of the three study sites (left to right) Bluff Meadow, Lodgepole Meadow, and Broomflat Meadow.
IV. The Influence of Water
C
Wetter vegetation (FACW and OBL species) was more prevalent around standing water in the Eastern region of Broomflat and in the Western regions of the Bluff-Lodgepole system
D
V. Conclusions Can montane meadow vegetation be classified by hydrologic need at the community level?
Yes. Using the classes outlined in the US Army Corps of Engineers’ National Wetland Plant List we found broad connections between distribution of wetland to nonwetland species and underlying hydrology across all three meadow sites.
How is the species diversity related to a meadow’s hydrologic health?
A greater diversity of species was found in Bluff and Lodgepole compared to Broomflat, however, correlation between species richness and water table depth was positive in Bluff but negative in Lodgepole.
Does the current distribution of meadow vegetation types suggest resilience against climate change?
A lower proportion of wetland species suggests that meadows in the San Bernardino mountains are less adapted to long-term drought conditions.
Acknowledgements
Figure 7. Bar chart of species richness vs. water table depth in all three meadows
• Figure 6. Maps depicting depth to water in Broomflat (A) versus the density of vegetative species (B) and the depth to water in Bluff and Lodgepole (C) versus the corresponding density of vegetative species (D) in those meadows. Note the legend for depth to water is the same across all three meadows (panels A and B).
Figure 9. Distribution of Meadow Species by National Wetland Plant List (NWPL) category. Plots chosen were broadly representative of expected subalpine meadow vegetation.
Drier meadows (Broomflat) generally exhibit diminished species richness relative to wet meadows (Lodgepole)
Special thanks to The Summer Science Research Program and my generous donor Mrs. Levings for making this experience possible. Thank you to my advisor Dr. Hillary Jenkins, the Environmental Science Department, US Fish & Wildlife, the US Forest Service, our research team: Marina Wesel, Paola Rosas, Abby Dimicco, and Kayla Smith, and our volunteers in the field: Dr. Eric Hill, Gavin Jewell, TJ Carson, and Isaac Dogbegah.