Hey everybody, hope you all enjoyed the long weekend! For my discussion I want to talk about how edge effects resulting from agriculture can affect native ecosystems. In a sentence, edge effects are a way of speaking about unique ecological characteristics at the edges between two different habitats (agricultural fields and forests, for example). For those of you who want more of a primer, here is a link to the Wikipedia page on edge effects.
https://en.wikipedia.org/wiki/Edge_effects
What got me thinking about this topic was when we were turning over compost for the gardens near the strawberries. I remember Amy saying that a certain kind of fly only turned up on the farm after she got some compost that had maggots in it. I wondered what the ecosystems might look like at the very local scale, since human development has fractured native ecosystems so much. To that end, I dug up a few articles (sorry in advance, they are primary research) on how crop fields interact with edge effects/edge species.
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12035
http://www.pnas.org/content/112/24/7402.full
http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0059659&type=printable
After reading these articles, do you have any questions or critiques? In your own experiences, on the farm or otherwise, can you think of a time you noticed differences in ecosystems at edges? If so, write a short reflection or even just list some observations you remember from the experience. My plan for class is to start with any reflections by everyone, then talk about the articles and how we do or do not believe their findings should be applied, and what we felt about them in general.
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ReplyDeleteI think this topic is very interesting because I do see edge effect in the farm and back home in California. A couple times in the farm, there are times that Amy and John will take us to see parts of the land conservation. The first time we went out to explore, I noticed there was this thin borderland on vegetation between parts of Amy’s farm and the conservation. There is a field of dried grasslands, with hardly any greens or vegetation for animals to live on. We do see lots of nests of a particular insect that I cannot remember at the moment. However, there is also lots of empty bird houses across the land preserve. A while back Amy explained to me how her dad was into making these bird homes and we even got to see how it looks like. It appears that a mouse has taken a liking to this home. In addition to that field trip, we got to see these amazing birds that encircle the woods from high above the trees. I got to witness seeing their graceful flying and song. In California, we were bless this year with the amount of rainfall. My hometown is usually surrounded by dry grass hills and sometimes frequent fires. However, when I came home for spring break, I saw lots green grass and shrubs from a distance. My sidewalk is full of green grass, and it is big deal for me. I am curious to learn on how people see these edge effects from their personal experiences.
ReplyDeleteThese studies are posing questions that are very relevant to my farm landscape, as our garden patches are tucked into the edges of a larger acreage that is managed for conservation. I have observed a certain amount of boundary-crossing of predatory and parasitic insects into our gardens and I've been wondering how to encourage more of that, especially in regards to soil predators and in the orchard space where fruit pest control is such a challenge.
ReplyDeleteQuestions and critiques I have especially in response to the "Edges in Agricultural Landscapes" and "Food production vs biodiversity" articles are--I don't know, but I suspect that these studies are looking at farms that use mainstream agricultural practices. I confess that I get a bit bristly the moment I hear anyone talking about comparing "organic" vs "conventional" farms, because organic the way it is currently practiced on most large farms is actually not that different from conventional agriculture. It's still monoculture and it still relies heavily on inputs. Often people will use studies that look at these "conventional organic" farms and use them to draw general conclusions about the in-viability of organic farming, while there are small organic farmers out there trying to develop more holistic, ecologically based systems that aren't acknowledged. (To give them credit, the authors of "Food production" do acknowledge some of the limitations of their study.)
One of my interests right now it thinking about how I can "blur the edges" between the wild landscapes and my crop gardens. I suspect that the fields looked at in these studies were planted to a single crop and the farmer was attempting to manage solely for that crop (meaning that if other plant species were present it was because weed control wasn't 100%). One thing I've been experimenting with (besides having gardens inter-planted with multiple crop species) is tucking patches of flowering plants in between some of my crops and/or letting certain crops (like arugula) flower and go to seed. What I've noticed in these flowering areas is an abundance of pollinators--flies, wasps, bees of all kinds. Some of the wasps, especially, may be parasitic species. My hope is that by creating small spaces within the production gardens that are attractive to predatory and parasitic insects, I can lure them in from the surrounding native perennial vegetation.
In the orchard, I hope this summer to create some perennial patches in between the trees that I plant with native plants that are attractive to predatory and parasitic insects. Again, this is an attempt to "blur the edges" or create patches within the production landscape specifically dedicated to habitat for beneficial insects.
One system that works with these ideas more extensively is permaculture. I'm taking a permaculture design course this year which I hope will give me many more ideas about how to better integrate my growing areas within my ecosystem so that the ecosystem can help me out with pests and fertility.
When I think of edge effect, I mostly think of brown-headed cowbirds, because they're the example that is used most frequently (in my experience) in ecology-type classes. I have seen several brown-headed cowbirds in Pennsylvania, and I think their brood parasite lifestyle is very interesting. I have not observed the effects on other songbirds of the area, though.
ReplyDeleteAs for the articles, my initial complaint was with the "Food production vs. biodiversity: comparing organic and conventional agriculture" framework of assuming that organic agriculture would be in basically a conventional agriculture set-up; the inputs might be different, but a monoculture is still a monoculture. I'm interested in the way that agroforests would deal with edge effect, as there would be less 'overhead' edge but more places for beneficial predator insects to live and hide.
Thank you for bringing this Josh! I particularly resonated with the second article on you list because it has relationship to what I see as my lifework. In geography and urban design, space is an important dimension of the work done. It is crucial to understanding the ecosystems of stories, histories, and physicalities of a certain place. It seems in the ways that it is layered and specific, space is important to understanding the natural stories, histories, and physicalities. I think this place of connection is a wonderful place for lots of different people to think together on their complexities. While urban space can be understood through many different lenses, those understandings also influence the "edges" of urban space - like suburbs and their transition to rural. I think about what ways policy and planning from the interior of the urban space is both interacting with the landscapes of humans and our implications in ecosystems. I would love to continue thinking through these ideas with the rest of the class, especially because we are all situated in different spaces and places with their own relationships to ecosystem edges, whether in a city or small town.
ReplyDeleteThis topic is very interesting and I honestly have not thought about edge effects before. I feel like I do see edge effects on the farm, as the gardens we work on while there are a part of and very close to a larger land conservation. There are parts where there seems to be a lot of grass and greens, but then at one point, the grass becomes more dried and straw like. I feel like when I see animals on the farm, it it usually in the more greener areas rather than in the straw like grass, which may be because it is more habitable to them. I'm interstested to hear more about this in class.
ReplyDeleteIn the British Ecological Society article, I was pretty unimpressed by their conclusions. It seems obvious to me that conservation efforts are more effective in low-productivity, organic agricultural landscapes and less effective in high-yield fields. I was also unimpressed by the findings of the PNAS article: whenever agricultural expansion occurs, the impact of such practices on the environment must be considered from a multi-layered perspective that takes into consideration total area, spatial configuration, carbon storage, biodiversity, and all living factors. Because of our limited view of environmental systems when it comes to implementing our agricultural systems, I tend think of human intervention/agricultural systems as generally detrimental to natural ecosystems. However, after Amy’s comment, I am pondering ways that humans could actually benefit ecosystems and increase biodiversity. Perhaps it is an idealization in a capitalist, colonial regime society, but I like to believe that we can begin to recognize ourselves as products of the earth, not conquerors of it, and learn how to integrate ourselves harmoniously into the larger environment. Edge effects are just one manifestation of human and natural interaction, and show the potential for both harm and benefits (e.g., physical and chemical conditions of border species), depending on how we utilize them.
ReplyDeleteThis is definitely an interesting topic and I appreciate you bringing it to the fore Josh. I have trouble identifying massive organisms like trees, so I'm still trying to work up to identifying individual species of flies and their specific habitats. In the future I'll definitely be keeping an eye out for organisms that like to live on the edge.
ReplyDeleteI don't know if I've noticed so much what occurs at the edges of ecosystems, but I've noticed more the drastic changes between ecosystems, and gradients that sometimes occur, such as with increasing altitude and the thinning of trees. Or I notice when an edge occurs, the startling nature of the edge. At the farm there is definitely edges, where raised beds start or end, or where the short grassy pathways meet the taller grasses. The tall grasses seem like a more mysterious place, filled with all sorts of plants and creatures, while the grass we trod on frequently has been tamed.
ReplyDeleteI thought the discussion about urban edges was interesting as well, and I want to learn more about the effects of urban expansion. I know that there are increasing amounts of wild animals (like bears and deer) in cities because we are encroaching on their land and severely limiting their space.
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