Impacts of Fog Drip on Survivorship and Growth of Native Herb and Shrub Seedlings on Santa Rosa Island

Overgrazing on Santa Rosa Island led to loss of topsoil in ridgeline groves of endemic island oaks (Quercus tomentella). Restoration specialists attempting to mitigate the impacts of wind and water erosion must determine efficient methods of reestablishing native vegetation. Planting pillows, burlap sacks filled with planting mix and attached to the bedrock substrate, may nurture seedlings long enough for their roots to penetrate the underlying sandstone. Since the island’s ridgeline habitat is often inaccessible during the rainy season, restoration efforts are largely confined to the dry summer months, during which condensed fog is an important source of moisture for plants. This study examined the performance of native seedlings in planting pillows under different conditions. Groups of seedlings including coyote brush (Baccharis pilularis), purple needle grass (Stipa pulchra), and yarrow (Achillea millefolium) were planted into each pillow, along with pretreated seeds of island ceanothus (Ceanothus arboreus). Seedling growth and survivorship was compared between pillows placed in the dripline of existing oak canopy, pillows fitted with fog capture structures, and pillows lacking any specific fog capture mechanism. Over a five week period, dripline seedlings demonstrated the highest growth and survivorship, seedlings planted with fog capture structures demonstrated intermediate success, and seedlings without the support of any fog capture source were the least successful

Soil Moisture on Soledad Ridge in Santa Rosa Island, Channel Islands National Park

Santa Rosa Island is one of the Channel Islands off the coast of southern California. Before the island was heavily grazed, Santa Rosa Island is thought to have had large stands of island oak trees, Quercus tomentella, that provided a critical source of water for the ecosystem by creating a “cloud forest”. Wind-borne fog collects on the leaves, branches, and twigs of the island oaks and other native shrubs. Once the water condenses it drips, falls, and soaks into the soil. Introducing cattle and especially sheep to the island has damaged the ecosystem and nearly decimated Santa Rosa Island of its native oaks and woodland plants. The Cloud Forest Restoration project aims to restore native trees and other plants to the central high ridge. Fog panels covered in mesh have been installed in areas on the ridge to collect fog and drip water down into the soil. In my study, soil moisture data was collected at areas 5 centimeters down slope from fog fences and above wattles (coconut fiber rolls used to prevent erosion of the slope). A second set of data was collected at areas with wattles only. Soil moisture readings were taken at 5 and 10 centimeters depths. The data suggests that the soil at fog fences is moister at both depths of 5 and 10 centimeters than at areas with wattles only. In addition, the soil was moister at 10 centimeters than 5 centimeters at sites with fog fences, suggesting substantial subsurface infiltration. This has implications for future planting projects because the extra fog drip provided by the panels does seem to be a significant source of moisture for new transplants

Effects of Habitat Restoration on Santa Rosa Island’s Soil Retention

Ranching began on Santa Rosa Island in the 1840’s, consequently introducing nonnative megafauna that put novel selective grazing pressures on endemic plant species. Their movement patterns also altered substrate integrity as the land became denuded of any stabilizing vegetation. Dense groves of island oak (Q. tomentella) are known to aid in sediment deposition and retention. The groves also function to collect water during periods of intense fog common to the island. This experiment sought to determine whether sediment is being lost or deposited on a ridge in the middle of the island containing a grove of Q. tomentella. The slope was divided into three sections based on vegetation, severity of slope, and substrate type. Three transects were installed in each section. Each of the nine transects where 60 meters long and composed of nails that were a uniform 15 cm above the surface, installed in January 2016. The results show all three sites experienced soil deposition, but the three sites were not significantly different from one another. Three transect lines intersected with erosion control structures. In those locations, nails were additionally installed upslope and downslope of the structure to determine if there were differences between the two locations relative to the erosion control structure. The results show areas upslope of these structures experience more soil deposition than areas downslope. This data informs future restoration attempts in their decision for placement of erosion control structures. Future studies could focus on areas of the slope would benefit most from fog collecting devices, as lack of water on the slope is a factor currently preventing the colonization of many plant species

Monitoring Fog Potential on Santa Rosa Island

Fog moisture on Santa Rosa Island plays an integral role in its ecosystems. It is important to understand how fog patterns could potentially effect the flora and fauna. I hypothesized that north facing side of the ridge will have more potential fog moisture due to the predominant wind direction coming from the north. This study used Fog capturing Screens to determine relative amount of fog on the north and south sides of the main ridge of the island. Three locations along the ridge had two Fog Screens placed on the north and south side of the ridge at similar elevations. Fog Screens are 12 gauge 1” by 1” wire mesh fencing with 40% shade cloth attached to the mesh fencing. Each Fog Screen is 1 meter long by 0.5 meter high supported a wooden and metal structure. The amount of moisture collected by a Fog Screen was recorded by a HOBO Rain Gauge Data Logger #RG3-M. I found that more moisture was collected on the north facing slopes of the ridge compared to the south facing slopes, supporting my hypothesis. With more moisture on the north facing slope, there is more potential to see wetter local conditions for plants and animals

Effects of Habitat Restoration on Soil Retention on Santa Rosa Island

Ranching began on Santa Rosa Island in the 1840’s, consequently introducing nonnative megafauna that put novel selective grazing pressures on endemic plant species. Their movement patterns also altered substrate integrity as the land became denuded of any stabilizing vegetation. Dense groves of island oak (Q. tomentella) are known to aid in sediment deposition and retention. The groves also function to collect water during periods of intense fog common to the island. This experiment sought to determine whether sediment is being lost or deposited on a ridge in the middle of the island containing a grove of Q. tomentella. The slope was divided into three sections based on vegetation, severity of slope, and substrate type. Three transects were installed in each section. Each of the nine transects where 60 meters long and composed of nails that were a uniform 15 cm above the surface, installed in January 2016. The results show all three sites experienced soil deposition, but the three sites were not significantly different from one another. Three transect lines intersected with erosion control structures. In those locations, nails were additionally installed upslope and downslope of the structure to determine if there were differences between the two locations relative to the erosion control structure. The results show areas upslope of these structures experience more soil deposition than areas downslope. This data informs future restoration attempts in their decision for placement of erosion control structures. Future studies could focus on areas of the slope would benefit most from fog collecting devices, as lack of water on the slope is a factor currently preventing the colonization of many plant species

Irrigation Efficiency of Santa Rosa Island Cloud Forest Restoration Project

Beginning in the 1800s, sheep and cattle ranching have caused significant erosion and devegetation of Santa Rosa Island, Channel Islands National Park. In an effort to contain what little soil is left and rebuild the native chaparral, the Cloud Forest Restoration Project is testing erosion control structures such as wattles, leaf litter fences and silt dams. This summer a drip irrigation system was installed along with fog capturing fences to supply water to native plants transplanted near the erosion control structures. As the project has grown, more irrigation has been added to increase the area available for transplanting. This irrigation system varies in elevation, slope, and diameter and lengths of irrigation lines. Because this project is experimentally monitored, it is important that all the transplants obtain the same amount of water. To check the efficiency of this system, the flow rates of 1.9L/hr rated pressure-compensating emitters along ¾” diameter polyethylene irrigation tubing were checked. Flow rates were relatively consistent at 1.53 L/hr, 1.60 L/hr and 1.59 L/hr for 1/3, 2/3 and the whole system turned on, respectively. Although one might expect the addition of more irrigation line and emitters to decrease water pressure and thus the flow rate of individual emitters, the flow rates of emitters were found to be unaffected, indicating the effectiveness of the pressure-compensation. However, the flow rates of emitters were consistently lower than their 1.9 L/hr rating. In conclusion, the irrigation system is currently providing equal water to each of the transplants, but at a rate lower than expected

The impact of restoration treatments on the germination of Quercus pacifica on Santa Rosa Island

Santa Rosa Island (SRI), part of Channel Islands National Park off the coast of Santa Barbara, is home to thousands of native and endemic flora and fauna. While full of unique island endemics, Santa Rosa Island has an extensive ranching history. A sheep and cattle ranching business was operated from the mid-1800s until 1998 and a deer and elk hunting operation ran until 2011. Together these operations led to extensive ecological degradation of the island ecosystem as a result of the grazing caused by ungulates. In December of 2015, the Cloud Forest Restoration Project began with the goal of restoring the island ecosystem through the initiation of active restoration techniques on a key ridgeline of the island, Soledad Ridge. Active restoration techniques and treatments include the installation of wattles for erosion control, fog fences to harvest water from fog, and the establishment of native plants. This study focuses on the impact of three different restoration treatments on the germination and survival of the endemic island scrub oak (Quercus pacifica). Island scrub oak seeds were collected in October of 2016 and planted on the restoration site in December of 2016. In July of 2017, an island scrub oak survey was conducted to determine the percentage of seedlings that successfully germinated and how the various restoration treatments impacted the germination rates. It was concluded that 646 of an estimated 3000 island scrub oak seedlings survived. There was a higher average percent of island scrub oak seedlings that successfully germinated under restoration treatments with either a wattle and/or fog fences in addition to an irrigation line. The next step of the study will be to focus on monitoring and measuring the overall growth of the establishment of the island scrub oak seedlings

Water infiltration in Different Soil Types on Santa Rosa Island

Research on the Cloud Forest Restoration Project at Soledad Ridge, Santa Rosa Island in Channel Islands National Park, aims to understand the properties of soil water infiltration, specifically field‚Äêsaturated soil hydraulic conductivity (Kfs). Measuring the soil water infiltration rate allows us to calculate potential water reaching plant root systems, the amount of water remaining on the surface, and potential water runoff. The soil types on Soledad Ridge have different organic matter origins including: Island oak trees (Quercus tomentella), annual grasses (eg. Bromus spp., Avena spp), and coyote brush (Baccharis pilularis). In some areas historic non-native herbivore overgrazing resulted in erosion of upper organic layers, exposing large sections of bedrock. We hypothesized that the hydraulic conductivity will be lower in bedrock sections as compared to the other soil types present on site. We used a modified bottomless bucket method (Mirus 2012) consisting of a small bucket approximately 20 centimeters in diameter with the bottom removed. The bucket was secured to each of the soil types to make a watertight seal: bedrock required caulking; the other soil types required grooving and twisting into the ground. The amount of time required for one liter of water to infiltrate was measured which yielded the hydraulic conductivity (Kfs). We found that bedrock had the lowest infiltration rate of approximately 1 Kfs whereas the other soils had a rate of approximately 100 Kfs. These results support our hypothesis that bedrock hydraulic conductivity is significantly slower than infiltration of the other soil types. These results can be used to design suitable planting and irrigation treatments in future restoration efforts at the cloud forest

The Pioneer of Santa Rosa Island

Santa Rosa Island which is part of the Channel Islands in California has a ranching history that goes as far back as the year 1843. While rich in history, the island is no longer “rich” in native plant populations due to the sheep, cattle and other livestock that once occupied the island. As a result of these grazers that the ranchers livelihood depended on, a great disturbance in the native plant population took place. It is up to plants such as Baccharis pilularis, commonly known as Coyote brush, to assist these endangered and threatened plants to once again flourish on Santa Rosa Island. In this study, a total of 200 cuttings were taken from the Coyote brush plant from different locations on the island. These cuttings were prepared with growth hormone and given time to grow their own roots in a humidity chamber for three-four weeks. The cuttings of Baccharis pilularis will be used as a pioneer plant to promote succession to shrub land on Santa Rosa Island. The Coyote brush will be planted on areas of the island that were devastated by the trampling and grazing of the cattle that once occupied the island and soil that has now been greatly affected by erosion. As a secondary succession plant, Coyote brush is utilized to reintroduce native plant species that were once prominent on Santa Rosa Island. Our goal and focus is to continue to collect and grow cuttings of this pioneer plant that has demonstrated success in the past in assisting the reintroduction of the various threatened and endangered plant species on Santa Rosa Island

Differential Growth in Santa Rosa Island’s Restoration

Restoration biology is a relatively new branch of biology and many restoration practices, while transferable, require some degree of tweaking. This is because the same plant ecosystem might be at different levels of ecological ruin and heavily influenced by everything from soil quality, to mountain aspect and sunshine levels, to fog-interception rates. Additionally, different plants of the same ecosystem might respond differently to varying treatments. The plants of this study are located on Santa Rosa Island, off the coast of Santa Barbara in Southern California. For the restoration at Soledad Ridge, the treatments include three combinations of drip-irrigation lines, erosion-control wattles, and fog-catching fences. For this study Coyote brush (Baccharis pilularis) and Purple-needle grass (Stipa pulchra) were assessed for growth. This was done by collecting applicable plant measurements (stem diameter, height, and canopy length and width) in 2017 and by both (1) comparing the numbers to measurements taken in 2016 and (2) comparing the differences among experimental treatments. The results show that B. pilularis does best in the fog fence treatment for all measurements, even after excluding casualties. Meanwhile, S. pulchra survivors do just as well in the wattle treatment as compared to the fog fence treatment after casualties are taken into account, but overall survivorship is better in the control treatment. This suggests that restoration of B. pilularis should include fog fences, but restoration of S. pulchra does not require additional measures beyond the control treatment of irrigation only