Diario de skhachikyan

Synthesis
The specialty I had chosen was native and non-native plants because early on in the semester I realized that a lot of plants we saw at our field sites were not native to the area. At the end of our trips, we gathered our data and concluded that there were about equal amounts of both types of plants. I did not expect to see such a large amount of non-native plants in the area.
The main observational trend noticed from our data was that there was a large amount of non-native plants in comparison to native. Research has shown that “the introduction of species beyond their native range as a direct or indirect result of human action causes changes in the ecosystems to which they are introduced” (Jeschke). These changes can sometimes result in the extinction of a species. For example, non-native plants bring with them pathogens, which can kill native plants. Another way non-native species can affect native species is by competing with them for space and nutrients. With the increase of non-native plants, the biodiversity decreases. Since the health of the biosphere is interconnected, this will affect human, ecosystem and biosphere health (Manchester). Lastly, my observations also demonstrated that the most plant diversity was found in the most natural habitats with the least human activity. I found the most native plants at JPL and that was also the location with the least human activity. Research shows that human activity alters the abiotic and biotic environment “by human-mediated dispersal of species into new regions, where they can naturalize and cause ecological, economic and social damage” (Kleunen). Thus, sustaining natural habitats are crucial to the health of the ecosystem. Plants are just a small part of the entire biosphere and yet we already see the negative impacts of human activity on them. We have a lot of non-native plants in the area, but instead we need to take care of what we already have.
Biodiversity is essential to the conservation of native plants and the very first step should be compiling a list of species that are in danger of extinction. If we don’t have data, how can we conserve? Research shows that plant conservation does not receive as much funding as animal conservation, thus it lags behind. Richard Corlett in his article, “Plant diversity in a changing world,” states “fewer than 20,000 plant species have been formally assessed so far at the global level using the IUCN Red List criteria.” This is a serious problem and an area that needs immediate attention by the public. Native plants will slowly start dying out if conservation efforts are not improved.

Works Cited

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Hamilton, J. G., et al. “Coexistence and interference between a native perennial grass
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Jeschke, Jonathan M et al. “Defining the Impact of Non-Native Species.” Conservation
Biology 28.5 (2014): 1188–1194. PMC. Web. 12 Dec. 2017.
Knapp, Sandra. “Rarity, Species Richness, and the Threat of Extinction—Are Plants
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“Plant diversity in a changing world: Status, trends, and conservation needs.” Plant
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Rangel, Danalit. “The Effect of Riparian and Arid Environments on Stomatal
Conductance in Baccharis salicifolia and Heteromelesarbutifolia.” Pepperdine
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Before this class, I barely knew about invasive species and their direct relation to biodiversity. Biodiversity boosts ecosystem productivity, thus it was very important to understand how invasive species were affecting California’s plant diversity. In her book, Invasive Plants of California's Wildlands, Carla Bossard argues that “invasive plants invade native habitat areas and vastly alter the ecological landscape by outcompeting and excluding native plants” (10). After completing our visits and analyzing our data, I realized that invasive species were definitely one of the reasons why native plants were not significantly more than non-native. How could this be fixed? It was scary to see a direct correlation between a decline in biodiversity and an increase in invasive species. If native plants were decreasing that just meant the entire ecosystem was being affected, since plants are a vital part of the health of our ecosystem. I soon learned that California’s invasive plant problems were severe and that if we didn’t do something about it soon, the future of California’s biodiversity did not look so bright. This encourages me to do more research and find out how I can help in ensuring our ecosystem is healthy.

During our observations we saw almost equal amounts of native and nonnative plants. This was a very interesting observation because I was not expecting to see so many nonnative plants. Towards the end of our field trips I knew that human activity played a big role in all of this, but I hadn’t considered diseases. I learned that some plants are dying down due to pathogens. For example, researchers discovered that “nearly all of the state's main tree species in mixed-evergreen and redwood-tanoak forests — including the coniferous timber species coast redwood and Douglas fir — may be hosts for P. ramorum” (Hamilton). There were many elements that affected our data and surprisingly disease played a significant role in this. One research actually showed that "greater plant richness dilutes the density of disease hosts and supports a greater number of insects," which are themselves resources for predatory and parasitic insects. This just shows that biodiversity is interconnected and when one category (plants) is affected, the entire ecosystem is affected. In this case, trophic levels are affected, so it's very important for us to consider plant disease as well when we talk about biodiversity. My conclusion was that this will affect biodiversity in the long run. Thus, it remains very important for us to take care of our ecosystem and ensure that plants are living in healthy conditions.

When we visited Steelhead Park, I started noticing that about 70% of the trees I was seeing were of one type. With the help of Professor Di Fiori we were able to identify the trees as Mule Fat (Baccharis salicifolia). I soon learned that the Mule Fat was a flowering shrub native to California and usually found in deserts or dry areas. I also learned that as part of a clean up effort, these shrubs had been cut down. They were in the process of growing back again. This shrub is “fairly drought-tolerant, and exhibits rapid growth to 8-10′ tall,” which explains why I saw so many of them (Watershed Nursery). After doing some research on this plant I discovered that environment plays a significant role in plant health. For example, research conducted by Pepperdine University students found that Baccharis silicifolia was abundant because it was found in a riparian environment. These students found that plants in riparian environments "would experience little water stress" (Rangel). It was interesting to find that trees I had never seen before were one of the most common native plants in California. Learning about the importance of plant health and environment I soon realized that there were many factors that played a role in plant abundance.

Our first stop in our series of field trips was the JPL Bridge. Upon the start of our observations I began to notice one particular type of tree standing out from the rest. I soon discovered that the Alder tree was very common in California. I had never seen an Alder tree before, so it triggered my interest and I started reading more about it. There are many different types of Alder trees, but the most common one we came across throughout our trips was the Alnus serrulata. Our trips were at different locations of the LA River, so I was not surprised when I found out that these trees are “native to boggy ground along streams/lakes/rivers, wetland margins, springs, spring-fed meadows, ditches and swampy fields” (Missouri Botanical Garden). I also learned that one of the benefits of the Alder tree is that it helps reduce water erosion. The Alder trees also seemed great for shade and nesting for birds and other wild life. Thus, I came to realize that these trees are immensely beneficial to the ecosystem and are a great part of its biodiversity.