Back to the Grassland, by Yinka and Ryan

When we (Yinka and Ryan) arrived at Nose Hill Park, we were pleasantly stunned to see that even in autumn, it was teeming with life. During our work at the park, we saw ducks in the pond, many bugs, and even a doe. That could be because this year was exceptionally warm. There was a pond, grasslands, and pockets of forests scattered throughout the landscape. Looking forward to our job, we took a long hike along a trail to our site. Soon, we had a transect set up on a grassy hillside and began collecting data. There were so many organisms around where we were working that doing a biomass pyramid seemed like a good idea. With some planned and intentional destruction of the ecosystem (i.e. ripping up the grass, digging up roots, clipping some shrubs and decimating the local insect population with a net), we had several giant splinters in our hands and a suitable amount of material to create a biomass pyramid of a Nose Hill grassland area. With that biomass pyramid, we will try to give you information on the details of a biomass pyramid, trophic levels, how biomass affects an ecosystem, and the ethical and scientific ideas associated with manipulating biomass in an environment.

If you’re goggling at this without a clue of what’s going on, here are some definitions to help you in your road to enlightenment. First of all, since we’re making a biomass pyramid, what is biomass? Biomass is the total mass of organisms in a specific area at one time. The biomass of an organism is measured by drying out the organisms to get rid of water and other inorganic molecules, then massing them on a scale. We used an electronic scale that could measure down to 0.01 grams. Another definition we need is of trophic level. In the most basic level, trophic levels are the different levels of feeding interactions in an ecosystem. For example, there are producers that synthesize energy-rich materials from the sun, soil, and/or water at the lowest level. They are consumed by herbivorous primary consumers, such as cows, which are on a trophic level above producers. The herbivores are then devoured in turn by carnivorous secondary consumers, which are on a level above primary consumers. There are tertiary, quaternary, and more. There are still many things about trophic levels we have to talk about, and the trophic levels that we found in Nose Hill will be discussed. However, before that, we need to go look at some concepts to understand what we’re blabbering on about.

As proposed in Biological Science (Freeman, S. 2008), the process of ingestion is only 10% efficient, but it is not wholly factual and is only an estimate. Many organisms barely absorb and use 1 or 2% of all the nutrients and biomass they ingest. Most of the matter they – and we – eat are sweated out, urinated, fall off our skin and is defecated. Therefore, it could be assumed that individual organisms at higher trophic levels have less mass than individual organisms at lower trophic levels (we will disprove this). But you think something like “wait up, I just had sushi yesterday. Are you saying I’m lighter than fish and rice?” Well, of course not. If that one meal of fish and rice was the only thing you’ve eaten since you’ve been born, you’d be lighter than fish and rice. But you have eaten thousands of meals in your lifetime. This tells us: “No! Individual organisms at higher trophic levels do not have to have less mass than individual organisms of lower trophic levels!”

Following this train of thought, if individual organisms of a high trophic level are heavier than individuals organisms of lower trophic levels, then that means that there needs to be enough individuals of the lower trophic level to support the population of the higher trophic level while having enough survivors to reproduce sustainably. With that, it can also be assumed that the total of organism of a higher trophic level have less mass than the total of organisms of a lower trophic level. There are exceptions where a higher level is larger than a lower level, such as in Bolivia’s Red Lake, but for the most part, the layers form a pyramid (hence a biomass pyramid).

Now, let’s start analyzing the ideas and topics within the Nose Hill ecosystem. Along with massing our specimens for the biomass pyramid, we explored the factors that affect the ecosystem, but we will not go into much detail about the environmental factors, and concentrate mainly on the biomass pyramid. For making the biomass pyramid, we collected four main pieces of data; the mass of grass dug up in a set area, the mass of herbivorous bugs collected in a set area, the mass of predatory bugs collected in a set area, and research on species that are rare or endangered in the area. While massing the bugs that we collected, we found something interesting; no individual insect was dense enough to record as 1/100 of a gram. This raises a question of how such tiny, insignificant organisms could support predatory organisms like birds. But here, the food chain comes into the story to help. The bird species found in Nose Hill, the black beaked magpie (Pica hudsonia), is an omnivore, so it consumes insects, seeds, nuts, rodents and carrion. In Nose Hill, grasses weren’t the only producers; wild prarie rose (Rosa arkansana) and prarie sage (Artemisia ludoviciana) were found, along with plants that appear to be smilacaceae and gaillardia aristata. Therefore, the bird species doesn’t belong only in the tertiary trophic level, but also in the secondary trophic level, and it doesn’t depend solely on the small insects. However, its role as a secondary consumer can still be studied in Nose Hill.

Figures 1.  Photos of some organisms that were researched for the biomass pyramid: The white tailed deer.

Figure 2.  Photos of some organisms that were researched for the biomass pyramid: the black beaked magpie.

Using the information collected, a biomass pyramid was created.

          As one can see simply from the explanations of biomass and its relation to an ecosystem, it is clear that a lack of balance in this system would very well result in an imbalance in the relationships and interactions that go on within the system. The idea of creating this imbalance in the biomass system is where the topic of ethics in ecology comes into play. In our current day and age, inventions and innovations are occurring in technology, lifestyles, and education everywhere we turn. As this occurs, and the social process of industrialization occurs, the world of business begins to expand past its current borders and begins to encroach upon those of others. A recent event occurred under the title of ‘Potatogate’ in which a company that grew potatoes wanted to expand its business by purchasing a key piece of land in the Albertan ecosystem that housed key species of endangered animals whose biomass roles in the ecosystem are vital. Through community activism, this impeding of industry on an ecological landscape was stopped. But why? The reason it was so important for this battle to be won for ecology relates to the ideas of biomass presented. In the biomass pyramid, one can see that as the pyramid goes up, the mass of the organisms in an area goes down. In cases of industrialization, much land ends up being cleared for the progression of industry. This disturbs the habitat of many animals. For insects, due to their small sizes and diversity, are many times, though hard, able to adjust to the new environments, but unfortunately, larger animals such the black-beaked magpie are not able to adjust as quickly. As biomass is measured over an area, where there may have existed one magpie, the land is reduced, causing more magpie to live in a concentrated area. The number of grasses and producers within the area doesn’t change, which means that the numerous insects feeding in the area will compete, and so will the birds who hunt for these insects. This competition can get very fierce and causes some major issues in the balance of the biomass. Thankfully, we have not experienced anything of this sort yet, but even the thought of this imbalance is quite catastrophic. This is why it is essential to keep natural lands such as Nose Hill safe, especially when they are one of very few left with such diverse species.

References

Wolfram Research. (2011). WolframAlpha: Computational Knowledge Engine. Retrieved from wolframalpha.com

The Royal Society. 2011. Aphid mass and fecundity, individual amino acid. Retrieved October 29, 2011 from: http://rspb.royalsocietypublishing.org/content/suppl/2010/07/26/rspb.2010.1304.DC1/rspb20101304supp2.pdf