Diario de lili11

It was brought up to our attention that as the groups went along the river, the sites were increasingly disrupted by human activity. Human activity is one of the main reasons why the ecosystem of the LA river is incredibly poor. According to the article “Effects of Biodiversity on Ecosystem Functioning: A Consensus of Current Knowledge”, human activity that introduced invasive species created an alteration in the ecosystem that creates changes that can be difficult or even irreversible to fix. The factors, such as resource availability and disturbance regime, can create a situation where the invasive plant species will dominate over the native species. In terms of plants, humans have planted non-native plants in areas rich ecosystem in order to grow exotic plants or crops. In particular, Los Angeles is known for its Mediterranean climate and has the ability to grow exotic plants. The humans took advantage of that by planting rare and exotic plants, but it came to the cost of the health of the ecosystem. However, the health of the ecosystem can still be recovered. Marsh Park is a prime example of the community helping restore the area to its most natural state by planting native trees. As mention in the study, the alteration of an ecosystem can create a greater difficulty in fixing it to the original state. In other words, the recovery process may be slow. The study also mentioned that having different species respond o different perturbation could help stabilize the ecosystem. It would also maintain the biodiversity and improve its own maintenance. In Marsh Park, the community started to reintroduced native plants into the ecosystem with the removal of non-native species. It did not show immediate results right away because, even with that information, Marsh Park still remains as an unhealthy site. However, over time, Marsh Park will be in a healthier state than previously. Ideally, we want all the sites to resemble JPL’s healthy ecosystem. Another good way to restore the health of an ecosystem efficiently is to plant indigenous relative to the area. In an article, “Indigenous trees restore soil microbial biomass at faster rates than exotic species”, the results showed that planting indigenous trees in soil microbial communities recovered fastest compared to exotic trees. This is crucial to the restoration of any invasive site because the indigenous trees help in restoration by management by increasing nitrogen concentration in the soil to enhance the growth of native plants. Based on the evidence, there are several ways to restore n ecosystem. Even though it is a slow process, if something is not done to the ecosystem, then the changes may be irreversible and the health cannot be restored. We only have one home to live on one planet. We have to do everything we can to take care of it.

References:
Hooper, D. U., et al. “Effects of Biodiversity on Ecosystem Functioning: A Consensus of
Current Knowledge.” Ecological Monographs, vol. 75, no. 1, 2005, pp. 3–35. JSTOR,
JSTOR, www.jstor.org/stable/4539083.

Li, Chun, et al. "Indigenous Trees Restore Soil Microbial Biomass at Faster Rates Than Exotic Species." Plant & Soil, vol. 396, no. 1/2, Nov. 2015, pp. 151-161. EBSCOhost, doi:10.1007/s11104-015-2570-x.

Professor Di Fiori brought to the class’ attention that the community is revitalizing Marsh Park into what it once was. In other words, the community is restoring to its health similar to JPL. Our team diagnosed Marsh Park as the least healthy sites by its low biodiversity and high chemical levels. However, even though it is the unhealthiest site, it was showing improvements in its health. Even though, non-native brings generally negative effects, there are some exceptions that made the ecosystem respond positively in some way. According to a scholarly article “Ecological Consequences of Biological Invasion”, the non-native plants can change the entire ecosystem of a site. In this case, Lower Arroyo had the highest variety of plants and that brings a different animal species. This is because there are different varieties of food source to eat for the animals, and thus creates a positive impact on the food web. This gives an explanation of Lower Arroyo highest biodiversity because of the increased trophic levels. However, it is important to remember that some of the non-native plants are invasive. In this site, non-native plant was recorded to have the highest diversity at same time native plants have the lowest diversity. This gives the idea that some of these non-native plants are extremely invasive if there were little recorded native plants. This might also be because there was apparent competition in the ecosystem. According to a study in an article “Apparent competition with an invasive plant hastens the extinction of an endangered lupin” shows that a native rodent Peromyscus maniculatus increased in their consumption of the native coastal dune plant Lupinus tidestomii due to the the proximity of the invasive grass Ammophilia arenia. In other words, invasive plants may compete against native plants by creating apparent competition that increases the pressure of native consumers. The results showed that the non-native plants have invaded the area and decreased the population of native consumers creates elevated levels of native plant consumptions. In other words, the native consumers have more pressure to eat native plants because there is low abundance of it. Hence, this can cause premature extinction of native plant species. This relates to our findings because Marsh Park, as mentioned before, was recorded to have the lowest native plant diversity with high nonnative plant diversity. It is true that the food level increases, but the overall health and ecosystem decreased because of the low diversity of native plants. However, it is tremendous that the community is restoring the health of Marsh Park.

References:
Dangremond, Emily M., et al. “Apparent Competition with an Invasive Plant Hastens the
Extinction of an Endangered Lupine.” Ecology, vol. 91, no. 8, 2010, pp. 2261–2271. JSTOR, JSTOR, www.jstor.org/stable/27860791.

Ehrenfeld, Joan G. “Ecosystem Consequences of Biological Invasions.” Annual Review of
Ecology, Evolution, and Systematics, vol. 41, 2010, pp. 59–80. JSTOR, JSTOR,
www.jstor.org/stable/27896214.

Steelhead Park at first glance was extremely vibrant with its high abundance of plants (it seemed very similar to a jungle). However, the plants seemed more brown and dry in comparison to other sites. We examined as access the health of Steelhead, and the results were second lowest low biodiversity out of all the sites. It is also noted that Steelhead had similar weather exposure and water availability similar to Lower Arroyo. There was a relative amount of nonnative plants in the area and animals, and it can be concluded that the combination of those two factors creates a situation that inhibits the growth of native plants. In the article “Conflicting Management Goals: Manatees and Invasive Competitors Inhibit Restoration of a Native Macrophyte”, the result showed that animals that consume primarily native plants and the growth of invasive creates a situation where it is difficult for the native plant's restoration. The experimenter planted the native plant Macrophyte in an ecosystem with non-native plants. It was found that 80% of the Native Macrophyte disappeared from the ecosystem. A possible explanation is that the animals greatly favored the consumption of native plant because it was the reason why some of the species thrive in that ecosystem in the first place. Additionally, the invasive plants dominate in growth and it gave a little area of the Macrophyte to grow. Another thing to point out is that a possible ratio of native to non-native species is the soil composition. In the article “Breaking New Ground: Soil Communities and Exotic Plant Invasion”, a diverse soil community also can respond to and mediate exotic plant invasions. Exotic plant invasions change the soil composition to meet the plant’s suitable living conditions. This allows some of the native and non-native plants to coexist. The non-native plants in not heavily dominated in comparison to Lower Arroyo, and this indicates coexistence in the ecosystem rather than the invasion. However, we are not exactly sure that the non-native plants will eventually dominate over the native plants. Currently, there is no restoration project being done at Steelhead. A restoration needs to be done in order for steelhead to not be in the same conditions as Marsh Park.

References:
Hauxwell, Jennifer, et al. “Conflicting Management Goals: Manatees and Invasive Competitors Inhibit Restoration of a Native Macrophyte.” Ecological Applications, vol. 14, no. 2, 2004, pp. 571–586. JSTOR, JSTOR, www.jstor.org/stable/4493559.

WOLFE, BENJAMIN E., and JOHN N. KLIRONOMOS. “Breaking New Ground: Soil
Communities and Exotic Plant Invasion.” BioScience, vol. 55, no. 6, 2005, pp. 477–487. JSTOR, JSTOR, www.jstor.org/stable/10.1641/0006-3568(2005)055[0477:bngsca]2.0.co;2.

Lower Arroyo was recorded to have the highest diversity, so the group mistakenly thought that it was the healthiest site. However, it was brought up to our attention that it has several non-native sand exotic species. Lower Arroyo gave a relatively amount of native species along with non-native species. In a scholarly article “Exotic plants contribute positively to biodiversity functions but reduce native seed production and arthropod richness”, there are some cases that non-native plants increase the biodiversity and arthropod richness. However, as mentioned in the title, the seed production decreases. It was noticed that Lower Arroyo has the highest biodiversity of insects, and it has several exotic plants including eucalyptus. Even though native plants attract most of the insect/arthropods population, the non-native plants brought a few non-native insects as well give more variety in the insect’s food source. However, it was also noted in the article that when native and non-native plants are raised together in an ecosystem, the non-native plants suppress seed production of native plants. This makes sense because of their higher abundance of non-native plants along with the reduction of the native plants on the site. Lower Arroyo displayed relatively warm temperatures and is connected to a vast amount of water. Another way to explain the relative abundance of non-native plants is their ability to use up more water because of their tendency to have higher sapping rate. According to the article “Comparative water use of native and invasive plants at multiple scales: a global meta-analysis”, the study demonstrates that the invasive plants have a tendency to have higher evapotranspiration rate and greater stomata conductance than the native plants. It was also noted in the article that plants enhance their water use in presence of hotter temperatures. This study provides an explanation of higher non-native plants percentage in comparison to other sites. Lower Arroyo was the ranked the second healthiest site in comparison to others.

References:
Cavaleri, Molly A., and Lawren Sack. “Comparative Water Use of Native and Invasive
Plants at Multiple Scales: a Global Meta-Analysis.” Ecology, vol. 91, no. 9, 2010, pp. 2705–2715. JSTOR, JSTOR, www.jstor.org/stable/27860847.

Cook-Patton, Susan C., and Anurag A. Agrawal. “Exotic Plants Contribute Positively to
Biodiversity Functions but Reduce Native Seed Production and Arthropod Richness.” Ecology, vol. 95, no. 6, 2014, pp. 1642–1650. JSTOR, JSTOR,

JPL is the least disturbed park because there was relatively little human activity that disrupted the natural ecosystem of the park. The area was full of plants in comparison to all the other sites. This is reflected in the native trees working together to create a healthier ecosystem because it comes with several benefits from other phyla. For instance, it also recorded that JPL had the most biodiversity across the board in all phyla. In iNaturalist, it was concluded that there was a high abundance of a few particular native species and very little non-native species. Based on the evidence, JPL was concluded to be the healthiest site. According to the article “Increasing Native, but Not Exotic, Biodiversity Increases Aboveground Productivity in Ungrazed and Intensely Grazed Grasslands”, the study showed the increasing the quantity of native plants help increase productivity by 42% and light interception by 44%. This is reflected in the appearance of the JPL because of the large biomass of native plants and the vibrancy of the plants. It was also noted that the root system in between plants seems heavily connected across the site; this can indicate the increased productivity. It is also able to adapt to sudden changes in the experiment conducted at different temperatures. JPL showed little change in its biodiversity when it was exposed to different temperatures. In the article “Context-dependency and the effects of species diversity on ecosystem function” demonstrate that effects of native diversity assist in community productivity and resistance to exotic invasion. This explains why there is little nonnative plant dominance because of the ecosystem resistance to its presence. It was found that “species-independent complementarity effect was the main contributor to the diversity effect on native plant cover, which increased as species richness in polycultures increased”. This describes the conditions at JPL with its richness in biodiversity because of the native plants as the major contributor. Based on the evidence, JPL was the healthiest site we have visited.

References:
Isbell, Forest I.1,2, forest.isbell@mail.mcgill.ca and Brian J.1, bwilsey@iastate.edu Wilsey.
"Increasing Native, but Not Exotic, Biodiversity Increases Aboveground Productivity in Ungrazed and Intensely Grazed Grasslands." Oecologia, vol. 165, no. 3, Mar. 2011, pp.
771-781. EBSCOhost, doi:10.1007/s00442-010-1877-9.

Liao, Huixuan, et al. "Context-Dependency and the Effects of Species Diversity on Ecosystem Function." Biological Invasions, vol. 18, no. 10, 2016, pp. 3063-3079, Biology Database,https://login.ezp.pasadena.edu/login?url=https://search.proquest.com/docview/1816295721?accountid=28371, doi:http://dx.doi.org/10.1007/s10530-016-1202-6.