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Examining changes in plant communities of alpine fellfield of the White Mountains

Sarah Ardell1, Karina Arzuyan1, Neil Singh2, Haleigh Yang1, Steven Zhou1

1University of California, San Diego, 2University of California, Davis

ABSTRACT

Alpine meadows are havens of and limiting resources, especially in arid and semi-arid climate zones. With exacerbating the seasonal variation of moisture and temperature, such havens continue to shift upward and reduce in range, disrupting vital that endemic organisms rely on. We examined plant communities of three alpine fellfield meadows in the White Mountains of California by conducting a follow-up survey to a baseline assessment performed in 2006 (Ababneh and Woolfenden 2010) of two meadows and surveying an additional to expand the scope of the study. Our analysis focuses specifically on how climate change influences meadow plant communities over time, as well as examining shifts in their reproductive . From these methods, we found plant communities of the original two meadows changed over time with the driest meadow resulting in the greatest local extinction of species and an overall increase in upland affinity species from 2006 to 2018. Additionally, there were abnormal temporal patterns in the reproductive phenology of many , with some blooming before and some after their expected bloom time. This resurvey demonstrates the importance of conducting baseline studies in alpine meadow habitats that may disappear over time and highlights the role of moisture and patterns in predicting shifts of plant community dynamics.

Keywords: climate change, alpine, alpine meadows, plant communities, phenology

INTRODUCTION conditions. Furthermore, alpine areas have also been shown to be sensitive to climate Recent shifts in global temperature and changes (Pauli et al. 2012), meaning that precipitation patterns are causing major alpine meadows may be under significant impacts on and altering the threat. plant communities within them (Penuelas et Moisture and temperature strongly al. 2018). Meadows are particularly sensitive regulate the composition of meadow to climatic changes (Lambrecht et al. 2006, vegetation (Berlow et al. 2003, Lambrecht et Sloat et al. 2015), which suggests that any al. 2006). Climate projections point to shifts in plant community composition could greater variations in precipitation be clear indicators of changing local climate (Trenberth 2011), and under both

CEC Research | https://doi.org/10.21973/N3BT0P Summer 2018 1/10

extremes—of or high precipitation— White Mountains in California intended to plant survival in meadows typically establish a baseline for future study on the diminishes (You et al. 2014, Gattringer et al. effects of climate change on meadow plant 2018). The presence of wetland species are communities (Ababneh and Woolfenden strong indicators of water content; lower 2010). The White Mountains have harsh numbers of wetland species or an absence environmental conditions with high altitude thereof indicate drier conditions (Tiner and large annual climatic variability. 1999). In addition to moisture levels, Nevertheless, many species of plants have increases in temperature have also been persisted in this harsh climate. Since the correlated with declines in alpine meadow original 2006 survey twelve years ago, mean species richness (Theobald et al. 2017). annual temperature has increased by 1°C in Drier and hotter conditions can increase the region (WRCC 2008). encroachment of more drought-tolerant In this study, our goals were to note species, shifting plant community dynamics differences in plant diversity and of alpine meadows. In cases such as grass- composition from the 2006 baseline study, dominated alpine meadows, shifts towards compare methodology of plant community lower precipitation or higher temperatures assessments, and examine an additional wet can cause transitions towards a or meadow to expand the scope of the baseline forest-dominated plant community, as both study for future analysis. We predicted that and trees have greater tolerance of there would be an overall decline in wetland drought (Wood 1975, Knapp et al. 2008). species diversity and cover compared to Climate change also creates more 2006. We also predicted the present-day stochasticity in functionality due would have a similar species to greater variations in weather conditions composition to the previous meadows due over time. This stochasticity can then to similar standing water presence. Lastly, manifest itself by shifting phenological we predicted blooming periods would patterns of plant growth and development. shift as a result of the fluctuations in According to Fu et. al (2018), growing precipitation and increases in temperature. seasons are delayed if precipitation occurs Using a baseline study, we sought to gain a later than normal. A shift in growing seasons stronger understanding of how alpine can severely affect the next generation of meadow species composition can change flowering plants’ blooming times. Thus, over time in response to shifts in climate. plant phenology may indicate how plant communities react to changes in the event of METHODS global temperature increases. Because of their ability to support many 2.1 Natural History of the Study System plant species and their sensitivity to We surveyed the plant communities of precipitation and temperature, wet alpine three alpine fellfield meadows on the upper meadows are excellent study systems for slopes of the White Mountains in Mono observing effects of changing abiotic factors County, CA, from August 1st to August 4th, on plant communities. A 2006 plant diversity 2018. Climatic conditions at these alpine survey on two wet alpine meadows at the

CEC Research | https://doi.org/10.21973/N3BT0P Summer 2018 2/10

elevations consist of a semi-aridic moisture 772 m directly east of Barcroft Station regime with high winds, extreme at an elevation of 3689 m (37o34'47.2" N, temperatures, and increased incidents of 118o13'29.9” W). It lies on a slight ultraviolet exposure and solar radiation depression between several rocky knolls and year-round. Precipitation typically occurs as two hummocks, measuring 68 m EW by 45 m snow or hail in winter months, with NS on a western aspect. Further occasional precipitation in spring and characterization and photos of these summer. The fellfield meadows here are meadows can be found in Ababneh and primarily fed by springs and streams Woolfenden (2010). The third meadow we resulting from snowmelt in winter months, surveyed, Marmot Meadow, is very wet, exhibiting predominately fen-like characterized by hummocks, an abundance characteristics. This annual abundance of of standing water, and many tussocks. It is moisture allows many unique plants that are located 80 m SE of Barcroft Road past the not typical of sagebrush communities to Barcroft Gate at an elevation of 3645 m, persist. Additionally, these meadows measuring 41 m EW and 32 m NS (Figure 1). provide important sources of water and forage for a plethora of despite the challenging climatic conditions that occur throughout the year, including marmots, pikas, bighorn sheep, and mule . We identified and delineated the three meadows and their boundaries according to pre-existing maps as well as abrupt changes in vegetation and slope gradient. The meadows were then classified as wet if there was standing water present and dry if it was absent. Figure 1: Panoramic photo of Marmot Meadow. The The first two meadows, Barcroft Gate third meadow surveyed was characterized by grassy hummocks, rocky outcroppings, and moist . Meadow and East Shield Meadow, were Transects ran 42 m (left to right in photo) by 31 m (top surveyed in 2006 (Ababneh and Woolfenden to bottom in photo). 2010) and again in this study. Barcroft Gate Meadow is a lower elevation, dry meadow 2.2 Research Design mosaic located approximately 180 m from Barcroft Gate Road (37o33'33.6" N, We first surveyed the vegetation of these 118o13'29.9" W). It lies southeast of a rutted meadows using the same methods as truck culvert at an elevation of 3370 m on a Ababneh and Woolfenden (2010), and slightly sloping easterly aspect. The meadow within the same week as the initial study. sampled for baseline comparison measures Our team performed a complete inventory 27 m EW by 90 m NS and contains several of the plant species present by walking in a gullies from ephemeral streams created by zig-zag direction through each meadow. We snowmelt runoff. East Shield Meadow is a also conducted 1 m point-intercept counts of higher elevation, rocky wet meadow found species along two transects, one with a NS

CEC Research | https://doi.org/10.21973/N3BT0P Summer 2018 3/10

axis and another going EW crossing at the 2.3 Statistical Analyses centroid of each meadow and stretching across to its boundaries. In addition to these To test differences in meadow community two methods, our team also measured composition over time in both meadows, we percent cover of meadow vegetation using a performed statistical analyses using JMP 0.25 m2 quadrat every five meters along the v13. Our team performed a same two transects used for point-intercept. multidimensional scaling analysis using the The use of two survey techniques allowed us percent cover of all species from each to compare their accuracy for plant meadow (both past and present) to visualize community assessments. the differences between plant community Each plant species was either identified in compositions. We also performed a chi- the field or sampled and photographed to squared analysis to test the effect of wetland identify later. They were then classified as affinity on species tendency to colonize or go wetland species or upland species based on locally extinct. Lastly, we tested for a the indicator categories of occurrence in relationship between quadrat and point- given by the U.S. Army Corps of intercept percent cover estimates by Engineers in the National Wetland Plant List. performing a linear regression. Species that are wetland obligates, wetland affiliates (found primarily in wetlands), or RESULTS partial wetland affiliates (found in both Barcroft Gate Meadow had a total of 22 wetlands and non-wetland environments) plant species consisting of 12 species of were classified as wetland species. Wetland shrubs and forbs, 5 species of sedges and non-tolerant species were classified as rushes, and 5 species of grasses (Table 1). upland species. East Shield Meadow had a total of 25 plant We also assessed changes in reproductive species consisting of 15 species of shrubs phenology of plants in the three meadows and forbs, 5 species of sedges and rushes, by observing the reproductive stage of the and 5 species of grasses (Table 2). Marmot majority of individuals for each species. We Meadow had a total of 31 species consisting categorized reproductive phenology into six of 19 species of shrubs and forbs, 7 species stages: 0. Not Reproducing, 1. Budding, 2. of sedges and rushes, and 5 species of Budding with Some Flowers, 3. grasses (Table 3). Flowering/Seeding, 4. Fruiting, and 5. The plant communities of both Barcroft Reproductive Senescence. We then Gate and East Shield changed over time; compared our field observations to the however, the overall plant community of typical flowering period of each species East Shield changed more than Barcroft using current Jepson Herbarium data to (Figure 2). In Barcroft, 11 species colonized determine if recent climatic factors are the meadow and 6 went locally extinct. In influencing blooming time. East Shield, 10 species colonized and 3 went locally extinct. The Marmot Meadow plant community is most similar to the plant community of East Shield in 2018.

CEC Research | https://doi.org/10.21973/N3BT0P Summer 2018 4/10

Table 1: Plant Community Composition of Barcroft Table 3: Plant community composition of Marmot Gate Meadow 2018 Meadow 2018

Table 2: Plant community composition of East Shield Meadow 2018

Figure 2: NMDS illustrating differences in plant communities from 2006 to 2018. The East Shield Meadow changed more than the Barcroft Gate Meadow between 2006 and 2018. Marmot meadow’s plant community is most similar to the plant community of East Shield Meadow in 2018. Space between points represents differences in overall plant community. Grey shapes represent plant communities in 2006, and arrows show change in meadow plant community from 2006 to 2018.

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In Barcroft Gate Meadow, colonizing species tended to have upland affinity whereas species that went locally extinct tended to have wetland affinity (N = 17, χ 2 = 4.01, P = 0.05; Figure 3). In East Shield Meadow, wetland affinity was not associated with species colonization or local extinction (N = 12, χ 2= 0.17, P = 0.73).

Figure 5: Correlation between percent cover estimate for quadrat and point intercept methods. The quadrat and point intercept methods produce very similar percent cover estimates for species they both find. Each point represents percent cover estimates for an individual species.

Figure 3: Wetland affinity of colonizing and locally extinct species. In Barcroft Meadow, a higher proportion of plant species that went locally extinct (were present in 2006 but not in 2018; dark grey) have wetland affinity than plant species that colonized (were absent in 2006 but present in 2018; light grey). In East Shield Meadow, there was no significant difference in proportion of species that have wetland affinity between those that colonized and those that went locally extinct.

Several species of forbs in the meadows showed phenological patterns different from their typical bloom times. Four species were blooming earlier than expected, nine species were blooming later than expected, Figure 6: Proportion of total species detected using and eight were blooming within their usual point intercept and quadrat methods. the quadrat bloom period (Figure 4). method (dark grey bars) detected a higher proportion of the total species in the meadow than the point intercept method (light grey bars) for all three meadows surveyed.

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Figure 4: Observed forb phenology patterns compared to expected bloom time intervals. Survey conducted on August 2 (Julian Date 214). Julian Bloom interval is the range of dates correlated with the days of the year in which each species is expected to be in bloom according to Calflora. Four forbs (blue crosses) were seen in a stage beyond flowering - either fruiting or senescing - despite our observation date being during their expected bloom interval. Eight forbs (red dots) were seen flowering during their expected bloom interval. Nine forbs (greens x’s) were observed in a flowering stage despite their expected bloom interval ending. Draba oligosperma was observed in a budding stage despite falling within its bloom period.

There was a strong correlation between decline. We found this pattern at Barcroft the percent cover measurements taken Gate Meadow, which dramatically changed using the point intercept versus quadrat in species composition, but not in East Shield methods (N = 90, R2 = 0.83 , P < 0.01 ; Figure Meadow. This difference is likely because 5). However, the quadrat method was able Barcroft Gate Meadow experienced much to detect more species than the point- more drying in the time between the intercept method in all meadows (Figure 6). baseline study and current study. Standing water was observed at Barcroft Gate DISCUSSION Meadow in 2006 (Ababneh and Woolfenden 2010) but was not present in 2018 during our We found shifts in the plant communities resurvey. This meadow was the driest site of of the meadows between 2006 and 2018; the three and saw a sharp decline in the however, the changes were idiosyncratic. proportion of wetland-affinity plants from Based on climatic data, we predicted that the 2006 survey (Figure 4). Forbs utilize wetland species richness and density would water allocated close to the soil surface,

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making this site uninhabitable for wetland on the snowmelt, soil moisture, and forbs and other wetland plants to sustain in temperature following snowmelt (Theobald (Debinski et al. 2010). et al. 2017). In 2018, the highest peaks of East Shield Meadow featured no Northern California experienced up to one significant change in the proportion of meter of snowfall in the early parts of March, wetland species between 2006-2018 and later than expected (Swain 2018). The late had standing water at the time of both snowfall led to cooler temperatures and studies. East Shield Meadow sits in a more moist further into the 2018 year. depression between two hummocks, which As described by Theobald et al. (2017), high- allowed for a greater accumulation and elevation blooming occurs soon after retention of water. This allows for greater snowmelt to optimize the growing season. moisture within the meadow, in contrast to Late blooming may have been in response to the flat, unidirectionally-sloping Barcroft the late snowmelt. Hotter and drier Gate Meadow that is more likely to lose summers may explain why four forbs water. bloomed early. In response to the dry Marmot Meadow, which was not surveyed season, some forbs with an expected bloom in 2006, had a similar plant species time of the fall bloomed earlier. As snowfall composition to that found in the 2018 survey fluctuates and temperatures remain higher of East Shield Meadow (Figure 2). However, than previous years, shifts in blooming Marmot Meadow’s plant community was periods are imminent, having the potential quite divergent from the 2006 survey of to affect herbivory and pollinator patterns Barcroft Gate Meadow. The differences (Theobald et al. 2017). between the two meadows are best Expanding this study to include more described by their respective topography. meadows would build upon the patterns we Marmot Meadow is characterized by rolling see as climatic factors continue to vary over hummocks throughout the meadow’s time. Though there was no difference in the boundaries, whereas Barcroft Gate meadow species percent cover estimates using point- is a flat, uniformly sloping meadow. intercept and quadrat methods (Figure 5), Conversely, Marmot Meadow and East the greater number of species captured by Shield Meadow had greater similarity in the quadrat method suggests that using the species composition due to similarities in quadrat method may create a better picture topographic features. Both occurred in rocky of the meadow plant composition (Figure 6). depressions capable of holding standing While conducting the quadrat method was water, fostering greater species diversity. more time-intensive, it creates replication Based on the predicted Julian bloom date within each meadow that strengthens our and the observed phenological stage, we statistical power to perform higher-level found 13 out of 21 forbs bloomed outside of analyses. Additionally, the quadrat method their expected blooming range (Figure 3). captures more species, including rare plants. These observed abnormalities could be We suggest using this method in future attributed to fluctuations in climate and studies to obtain a more adequate precipitation patterns. Blooming representation of the meadow community. fluctuations in alpine environments depend

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