Reservoir Canyon Hike
For my photo essay, I chose to hike Reservoir Canyon which is only a short walk from my neighborhood on the east side of San Luis Obispo. The hike offers unique views of SLO and the surrounding communities while also acting as a great access point to the outdoors only a few miles from downtown. The route I took began at the end of San Luis Dr. and proceeded up along the top of the ridge. While it is a relatively short hike, it is quite steep in many places and even involves a rope-assisted scramble at the start of the trail. As I made my way up the ridge I documented the various ecological phenomenons I noticed both on and around the trail.
On the initial climb up there was significant erosion both on and near the trail. With the first 100 meters of the trail being the steepest, erosion was greatest here. Over the past years, it is evident that heavy rainfall and steep terrain have created numerous deep trench-like ravines along the trail. As years have passed this issue has only compounded worsening the trail condition. In this area, dry hard-packed soil was covered by loose fragments of weathered rock and eroded soil as pictured above. Due to the steep nature of the trail these loose fragments made for a slippery climb up.
On steeper sections of the trail, erosion was significantly worse. In many places, erosion has also been worsened by the passage of both people and animals who walk on the trail thus expediting the erosion process. As pictured above, last week’s rainfall created small rivulets in the center of the trail. Future rain will likely deepen and expand these rivets creating larger ravines as was the case at the start of the trail. However, the remaining vegetation growing in these areas has helped stabilize these slopes limiting the erosion only to the exposed surfaces. In many places, exposed roots could be seen clinging to the slope where the soil had eroded out beneath it.
In addition to the erosion, there was a considerable amount of weathering near the larger rocks along the ridge. Most of the weathering I noticed was physical weathering caused by wind and water. At higher elevations at the peak of the ridge, there was more exposed rock due to greater exposure to wind, rain, and other natural erosion agents. Due to this, much of the exposed rock has slowly weathered away over time, breaking down into subsequently smaller fragments of rock as seen above. While there was considerable evidence of physical weathering throughout the trail, I noticed some biological weathering as well. In some places, trees had begun growing in and around rocks thus breaking them down through biological weathering. The biological weathering I observed was at lower, less exposed elevations where larger trees were more present.
As my hike continued I was eager to see what other ecological phenomena I would encounter. After a steep initial ascent, the trail flattens out offering a wide view of the various plant communities in Reservoir Canyon. Plant communities are recognizable groups of plants that inhabit a distinct area. When I reached this vantage point I noticed a rather sharp ecotone between the grassland (in the foreground) and chaparral plant communities (dark green shrubs further back) as pictured above. An ecotone is a transition zone between two or more plant communities. Ecotones can either be broad or sharp depending on the size of the transition zone. The grassland community was characterized by various annual grasses, Yucca, and Ephedra plants, which are all low growing soft shrubs and grasses. The chaparral community was dominated by Chamise and Spiny Redberry which are stiff and woody plants that tend to be about waist to head-high as seen in the distance.
As I hiked further it became apparent that the chaparral community was confined just to the south and west-facing slopes whereas the grassland community was confined to the north and east-facing slopes as well as the top of the ridge. Due to these district regions these communities inhabit, there were noticeable, sharp ecotones especially along the top of the ridge. In the chaparral communities, there was significantly less erosion due to deeper roots stabilizing the slope. With the grassland community, the lack of leaf cover increases exposure making it more susceptible to erosion.
As I ventured further up the trail these ecotones became more apparent. Many of the chaparral communities in Reservoir Canyon can be found occupying small gullies where rainfall flows into. In the center of these gullies, there is evidence of dried stream beds from where water has flowed in the past. While the close access to water helps the chaparral plants they also serve an important purpose stabilizing these slopes which are prone to erosion. Above these gullies on flatter slopes is where I noticed the grassland communities as seen in the photo above.
As I navigated my way through the chaparral and grassland communities I noticed a few familiar plants I had learned in a past dendrology class. Of these plants, it was interesting to see how some of them have adapted to California’s drought-prone climate and how others have not. Chamise has various adaptations making it a resilient drought-tolerant plant. Its short needle-like leaves and small diameter stems help the plant conserve water for prolonged periods of time. Furthermore, its leathery leaves prevent water loss allowing it to retain water throughout droughts.
The next plant I recognized was Sawtoothed Goldenbush which could be found throughout the grassland community. While the image above may seem like the plant is dead it is actually a living drought-tolerant plant. Over the course of its existence, numerous adaptations have prevailed allowing the plant to survive for long periods of time without adequate rainfall. Some of these adaptations include smaller summer leaves to maximize water use and small surface hairs for added protection against sun and wind. Additionally, during periods of drought, there is a reduction in plant transpiration thus minimizing water loss due to photosynthesis but positively contributing to the longevity of the plant. While the brownish color may be deceiving, these adaptations allow it to survive despite the lack of rain.
A few moments later I stumbled upon a grove of Spiny Redberry which is a dominant plant in the chaparral community. As seen in the photo above, the leaves remain green despite the minimal rainfall Reservoir Canyon has received. Of the many drought-resistant adaptations Spiny Redberry has formed, its deep roots have access to soil moisture which allows it to outcompete other shallow-rooted plants nearby. Furthermore, its small leathery leaves allow for more efficient use of water while minimizing water loss through transpiration.
After a nice brisk hike, I eventually reached the metal tower at top of the ridge. From the top, there were great views of Cal Poly, Bishop Peak, Maddona mountain, and even the Pacific ocean far in the distance. The hike is relatively short at roughly 2.5 miles round trip yet in that distance you gain about 1200 feet of elevation. As I trekked up the trail I found it extremely interesting to be able to apply past and present knowledge to the diverse ecosystem around me. In doing this I saw firsthand the effects of erosion, the interplay between two plant communities, and how plants have adapted to California’s drought-prone environment. Overall, I was pleasantly surprised by this new hike and I plan on returning in the very near future.
