Follow the Leader: The study of native shrub species advancing into grassland. Samantha Lough 1 ; Dr. Chrys Rodrigue 4 ; Jade Dean 4 ; Nancy Ko 2 ; Dr. Paul Laris 4 ; Koang KC Chea 1 ; Trina Ming 1 ; Darrell Patterson 5 ; Randy Peterson 3 ; Brian Nagy 4 ; Kyra Engelberg 4 Geosciences Diversity Enhancement Program, California State University Long Beach 1: Lakewood High School, 2: Los Alamitos High School, 3: Wilson High School, 4: California State University Long Beach, 5: Long Beach Polytechnic High School Abstract Introduction Methods Results Acknowledgements References Conclusion Discussion I would like to thank the National Science Foundation [award # ] for funding GDEP at CSULB. I would also like to thank Dr. Chrys Rodrigue, Dr. Paul Laris, and Sr. Randolpho Peterson for providing guidance throughout the entire research process, Brian Nagy for answering any and all technical questions, and Koang Chea, Jade Dean, Nancy Ko, Trina Ming, and Darrell Patterson for help with collecting all the data out in the field as well as always being there for support and entertainment. Field work: Transects were picked based on a map produced by Kyra Engleberg. The transects were placed at an area that included a definite boundary between CSS and the annual grasslands. The transect tape began in the transition zone and was laid out 25 meters into the CSS and then 25 meters into the grassland (Fig. 5). At every five meters along the tape, a 1 x 1 meter quadrat was used. The quadrat was utilized to identify (Fig. 6 and 7) and quantify (in percent cover) plant species along the transect (Fig. 3). Because of overlapping canopies, percent cover sometimes ended up over a hundred percent. Unidentifiable species were described with much detail and a sample was collected to be identified later. At the transition zone, five meter, and ten meter marks in grassland as well as in CSS, soil samples were taken from the upper level and the lower levels using a soil auger (Fig. 4). In addition to the soil samples, at the same meter marks, a soil penetrometer was used to take three soil compaction readings within the quadrat (Fig. 6). Lab work: In the lab, all the data collected from the field was entered into a database, with fields for the transect location, the soil compaction readings, and the plant species and percent cover. This database was then linked in a GIS to additional spatial data, including maps of topography and disturbance. This data set was further analyzed for patterns, then compiled into separate spreadsheets. Using Chi Square analysis, the data was evaluated for significant differences. Figure 1 Figure 2 Our study consists of research done within the La Jolla Valley. The purpose was to examine whether or not certain native shrub species led the way in advancing into the grassland. Transects were lain across stable boundaries as well as recovering boundaries. Along the transect plant species were identified together with their percent cover. The collection of species data was then analyzed for patterns and specific differences. It has been found that six native shrub species are pioneer species that aid CSS by leading the way into the annual grassland to potentially create a suitable environment for other native shrubs. These species include Artemesia californica, Eriogonum fasciculatum, Baccharis pilularis, Mimulus auirantaicus, Nassella pulchra, and Melica imperfecta. This project found that specific native shrub species are more capable of establishing in grassland territory. The following appear to be pioneer species, Artemesia californica, Eriogonum fasciculatum, Baccharis pilularis, Mimulus auirantaicus, Nassella pulchra, and Melica imperfecta. We conclude that future restoration projects should prioritize the species that have demonstrated the ability to establish in grasslands, such as those in Table 1. Restorationists should avoid using species that have not demonstrated the ability to colonize in grasslands regardless of whether they are found in the proximity to the restoration site. Future research should focus on whether these other species can establish once the pioneer species are in place. Chea, K Does Slope and Aspect Affect California Sage Scrub Recovery? GDEP Research Symposium (CSULB). Clements, F The Relict Method in Dynamic Ecology. Journal of Ecology 22, 1: Freudenberger, D.O.; Fish, B.E.; Keeley, J.E Distribution and stability of grasslands in the Los Angeles Basin. Bull. Southern California Acad. Sci 86, 1: 13 26 Keeley, J. Postfire Recovery of California Coastal Sage Scrub. American Midland Naturalist 111, 1: Ming, T Does Size Matter?. GDEP Research Symposium (CSULB). Patterson, D Is Carbon and Nitrogen the Reason in Season?. GDEP Research Symposium (CSULB). Wells, P Vegetation in Relation to Geological Substratum and Fire in the San Luis Obispo Quadrangle, California. Ecological Monographs 32, 1 : Westman, W Diversity relations and succession in Californian coastal sage scrub. Ecology 62, 1: Westman, W Factors influencing the distribution of species of Californian coastal sage scrub. Ecology 62, 2: Chart 1 shows the average percent cover of the native plant species within the CSS, the transition zone, and the grassland. It also breaks up the percent cover between the transects with stable boundaries and recovering boundaries. Southern California is one of the worlds many biodiversity hotspots. A biodiversity hotspot is a habitat with a significant amount of biodiversity that is threatened by destruction. Covering a predominant portion of this hotspot is California Sage Scrub (CSS). This environment houses the California Gnatcatcher, an endangered bird species that lives only in CSS. CSS is threatened by two major variables, persistent development of housing and other structures plus the invasion of exotic grasses that were introduced in the late 18 th century. Currently there is only % of the original CSS habitat, with much of the remaining CSS degraded within State Parks and conservation areas. Post- disturbance, studies have shown that CSS recovers at a slower rate than annual grasslands. One hypothesis is that CSS thrives on areas with steeper slopes in coarse, rocky soil whereas the grasses prefer a flat slope with a finer soil texture. Clements (1934) discusses that the landscape used to be covered solely by native grasslands but, Wells (1962) argues that the annual grasslands invaded land previously dominated by CSS. Another hypothesis concerns land disturbance, including fires, overgrazing, and mechanical disturbance. Keeley (1984) suggests that due to too frequent fires, the CSS is unable to recover. Freudenberger (1987) believes it to be a combination of the frequent fires, but also overgrazing of the land. Others have mentioned mechanical disturbance as a factor, but it is usually discussed in the context of overgrazing. The purpose of this study was to determine the different factors that may influence as well as limit the advancement of CSS into the areas controlled by grasslands. In order to accomplish this, focus was placed on mapping and comparing the changes in the boundaries between CSS and grassland during the time period of the 1980s-2000s. We also examined whether or not certain shrub species led the way in advancing into the grasslands. Westman (1981) studied the factors that affect the development of mono-specific species stands. Stylinski and Allen (1999), who studied intensively disturbed areas, found that only two CSS species were able to successfully colonize areas dominated by non- native grasses. These are Eriogonum fasciculatum and Baccharis sarothroides. Table 1 Chart 1 Table 1 depicts the native shrub species that were found thriving within the grassland. The number of quadrats containing native shrubs that appear to be advancing into the grassland and at which meter along the transect they were found. Study Sites Figure 3 Figure 4 Figure 5 Figure 6 Within Table 2, the species in the CSS, proven to be leading the advancement into the grasslands are shown. It is broken down to recovering and stable transects, with the quadrat counts for each leading species and the sum of the remaining species as well as their chi square values. Native Shrub Species in the Grassland NameNumber of ShrubsMeter Location Salvia leucophylla 230m, 35m Baccharis pilularis 135m Isocoma menziesii 230m, 50m Hazardia squarrosa 145m Eriogonum fasciculatum 435m, 40m, 45m, 50m Recovery vs. Stable: Leading Native Species Artemesia californica Eriogonum fasciculatum Baccharis pilularis Mimulus aurantiacus Nassella pulchra Melica imperfecta Other Recovery Stable Chi Square Probability Difference > 0.05 Table 2 This study found that certain native shrub species are leading the advancement of CSS into grasslands. A chi square analysis has proven that Artemesia californica, Eriogonum fasciculatum, Baccharis pilularis, Mimulus auirantaicus, Nassella pulchra, and Melica imperfecta all have chi square values less than 0.05, which indicates that they are disproportionately more common in the recovery versus stable boundaries. This significant difference proves that these six native species may be considered pioneer species (Table 2). Pattersons and Mings research explored various edaphic factors that have been proposed as influences on CSS and grassland dominance. Their work has shown that neither carbon to nitrogen ratios nor grain size affects CSS in any way. Cheas research evaluated elevation, slope, and aspect and found that only elevation and aspect were significant in differentiating stable from recovering CSS boundaries. Westman (1981a) discusses possible allelopathic effects emitted from the shrubs or the dominance of herb species as factors of species distribution. Westman (1981b) explains other factors that influence the distribution of certain Salvia species, and their development as mono-specific stands. Our study results support Wells (1962) theory that annual grasses invaded CSS. They counter Keeleys (1984) and Freudenberger et als (1987) notion that frequent disturbances prevents CSS recovery. In our study area grazing ended 45 years ago and there has been but a single fire in 1993 during the study period. They also confirm the findings of Sylinski and Allen that CSS is slow to recover in some cases and that only a few species can invade areas dominated by exotic grasses. Some Native California Plants Scientific NameCommon Name Artemesia californica CA Sagebrush Baccharis pilularis Coyote Bush Encelia californica CA Bush sunflower Eriogonum fasciculatum CA Buckwheat Hazardia squarrosa Sawtooth Goldenbrush Isocoma menziesii Coast Goldenbrush Melica imperfecta Onion Grass Mimulus auirantaicus Sticky Monkey flower Nassella pulchra Purple Needlegrass Salvia leucophyila Purple Sage Salvia mellifera Black Sage Figure 6: CA Buckwheat Figure 7: CSS